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Sample records for coated particle fuel

  1. Automated optical microscopy of coated particle fuel

    SciTech Connect

    Kercher, Andrew K; Hunn, John D; Price, Jeffery R; Pappano, Peter J

    2008-01-01

    Fundamental technological advances have occurred during the 20 year hiatus in US research on coated particle nuclear fuel. As part of the recent US Department of Energy s Advanced Gas Reactor Fuel Development and Qualification program, Oak Ridge National Laboratory has utilized advancements in computer automation, digital imaging, and image analysis to modernize US optical microscopy techniques for coated particle nuclear fuel. Automated optical microscopy has enabled detailed and objective analysis of individual particles (hundreds of measurements per particle) and of large sample sizes that far exceed the capabilities of conventional manual microscopy methods (analysis of 1500-5000 particles is common). Demonstrative examples of the capabilities of this automated optical microscopy are given for: (a) shadow imaging of kernels, coated fuel particles, and graphite matrix overcoated particles and (b) cross-sectional analysis of coated fuel particles to determine layer thicknesses.

  2. Preparing oxidizer coated metal fuel particles

    NASA Technical Reports Server (NTRS)

    Shafer, J. I.; Simmons, G. M. (Inventor)

    1974-01-01

    A solid propellant composition of improved efficiency is described which includes an oxidizer containing ammonium perchlorate, and a powered metal fuel, preferably aluminum or beryllium, in the form of a composite. The metal fuel is contained in the crystalline lattice framework of the oxidizer, as well as within the oxidizer particles, and is disposed in the interstices between the oxidizer particles of the composition. The propellant composition is produced by a process comprising the crystallization of ammonium perchlorate in water, in the presence of finely divided aluminum or beryllium. A suitable binder is incorporated in the propellant composition to bind the individual particles of metal with the particles of oxidizer containing occluded metal.

  3. Diagnostics of coated fuel particles by neutron and synchrotron radiography

    SciTech Connect

    Momot, G. V.; Podurets, K. M.; Pogorelyi, D. K.; Somenkov, V. A.; Yakovenko, E. V.

    2011-12-15

    The nondestructive monitoring of coated fuel particles has been performed using contact neutron radiography and refraction radiography based on synchrotron radiation. It is shown that these methods supplement each other and have a high potential for determining the sizes, densities, and isotopic composition of the particle components.

  4. Optical inspection of coated-particle nuclear fuel

    NASA Astrophysics Data System (ADS)

    Price, Jeffery R.; Hunn, John D.

    2004-05-01

    In this paper, we describe the inspection of coated particle nuclear fuel using optical microscopy. Each ideally spherical particle possesses four coating layers surrounding a fuel kernel. Kernels are designed with diameters of either 350 or 500 microns and the other four layers, from the kernel outward, are 100, 45, 35, and 45 microns, respectively. The inspection of the particles is undertaken in two phases. In the first phase, multiple particles are imaged via back-lighting in a single 3900 x 3090 image at a resolution of about 1.12 pixels/micron. The distance transform, watershed segmentation, edge detection, and the Kasa circle fitting algorithm are employed to compute total outer diameters only. In the second inspection phase, the particles are embedded in an epoxy and cleaved (via polishing) to reveal the cross-section structure of all layers simultaneously. These cleaved particles are imaged individually at a resolution of about 2.27 pixels/micron. We first find points on the kernel boundary and then employ the Kasa algorithm to estimate the overall particle center. We then find boundary points between the remaining layers along rays emanating from the particle center. Kernel and layer boundaries are detected using a novel segmentation approach. From these boundary points, we compute and store layer thickness data.

  5. Microscopic analysis of irradiated AGR-1 coated particle fuel compacts

    SciTech Connect

    Scott A. Ploger; Paul A. Demkowicz; John D. Hunn; Jay S. Kehn

    2014-05-01

    The AGR-1 experiment involved irradiation of 72 TRISO-coated particle fuel compacts to a peak compact-average burnup of 19.5% FIMA with no in-pile failures observed out of 3 x 105 total particles. Irradiated AGR-1 fuel compacts have been cross-sectioned and analyzed with optical microscopy to characterize kernel, buffer, and coating behavior. Six compacts have been examined, spanning a range of irradiation conditions (burnup, fast fluence, and irradiation temperature) and including all four TRISO coating variations irradiated in the AGR-1 experiment. The cylindrical specimens were sectioned both transversely and longitudinally, then polished to expose from 36 to 79 individual particles near midplane on each mount. The analysis focused primarily on kernel swelling and porosity, buffer densification and fracturing, buffer–IPyC debonding, and fractures in the IPyC and SiC layers. Characteristic morphologies have been identified, 981 particles have been classified, and spatial distributions of particle types have been mapped. No significant spatial patterns were discovered in these cross sections. However, some trends were found between morphological types and certain behavioral aspects. Buffer fractures were found in 23% of the particles, and these fractures often resulted in unconstrained kernel protrusion into the open cavities. Fractured buffers and buffers that stayed bonded to IPyC layers appear related to larger pore size in kernels. Buffer–IPyC interface integrity evidently factored into initiation of rare IPyC fractures. Fractures through part of the SiC layer were found in only four classified particles, all in conjunction with IPyC–SiC debonding. Compiled results suggest that the deliberate coating fabrication variations influenced the frequencies of IPyC fractures and IPyC–SiC debonds.

  6. Microscopic analysis of irradiated AGR-1 coated particle fuel compacts

    SciTech Connect

    Scott Ploger; Paul Demkowicz; John Hunn; Robert Morris

    2012-10-01

    The AGR-1 experiment involved irradiation of 72 TRISO-coated particle fuel compacts to a peak burnup of 19.5% FIMA with no in-pile failures observed out of 3×105 total particles. Irradiated AGR-1 fuel compacts have been cross-sectioned and analyzed with optical microscopy to characterize kernel, buffer, and coating behavior. Five compacts have been examined so far, spanning a range of irradiation conditions (burnup, fast fluence, and irradiation temperature) and including all four TRISO coating variations irradiated in the AGR-1 experiment. The cylindrical specimens were sectioned both transversely and longitudinally, then polished to expose between approximately 40-80 individual particles on each mount. The analysis focused primarily on kernel swelling and porosity, buffer densification and fracturing, buffer-IPyC debonding, and fractures in the IPyC and SiC layers. Characteristic morphologies have been identified, over 800 particles have been classified, and spatial distributions of particle types have been mapped. No significant spatial patterns were discovered in these cross sections. However, some trends were found between morphological types and certain behavioral aspects. Buffer fractures were found in approximately 23% of the particles, and these fractures often resulted in unconstrained kernel swelling into the open cavities. Fractured buffers and buffers that stayed bonded to IPyC layers appear related to larger pore size in kernels. Buffer-IPyC interface integrity evidently factored into initiation of rare IPyC fractures. Fractures through part of the SiC layer were found in only three particles, all in conjunction with IPyC-SiC debonding. Compiled results suggest that the deliberate coating fabrication variations influenced the frequencies of IPyC fractures, IPyC-SiC debonds, and SiC fractures.

  7. A high power, Coated Particle Fuel Compact Radioisotope Heat Unit

    NASA Astrophysics Data System (ADS)

    King, Jeffrey C.; El-Genk, Mohamed S.

    2001-02-01

    A Coated Particle Fuel Compact, Radioisotope Heater Unit (CPFC-RHU) is proposed, which is capable of generating thermal power in excess of 27 W. This power output is more than four times that of a Hexa-RHU, which generates only six watts of thermal power. The design of the CPFC-RHU is identical to that of the Hexa-RHU, except that the six Pt-30Rh clad fuel pellets and the POCO graphite support in the latter are replaced with single-sized, ZrC coated, 238PuO2 fuel particles ~500 μm in diameter. In addition to fully retaining the helium gas generated by the radioactive decay of the fuel, the CPFC offers promise for enhanced safety. Thermal analyses of the CPFC-RHU show that while the Hexa-RHU is suitable for use in a radioisotope power system (RPS) operating at a converter hot-side temperature of 473 K, the CPFC-RHU could also be used at higher temperatures of 773 K and 973 K with a thermal efficiency >60%. Even at a 473 K converter hot-side temperature, the CPFC-RHU offers higher thermal efficiency (>90%) than the Hexa-RHU (~75%). The CPFC-RHU final design provides constant temperature, with almost uniform radial heat flux to the converter, for enhanced performance, better integration, and higher overall efficiency of the RPS. The present CPFC-RHU fills a gap in the power needs for future space missions requiring electric power of 1-15 W, from a single RPS. .

  8. Development of an Integrated Performance Model for TRISO-Coated Gas Reactor Particle Fuel

    SciTech Connect

    Petti, David Andrew; Miller, Gregory Kent; Martin, David George; Maki, John Thomas

    2005-05-01

    The success of gas reactors depends upon the safety and quality of the coated particle fuel. The understanding and evaluation of this fuel requires development of an integrated mechanistic fuel performance model that fully describes the mechanical and physico-chemical behavior of the fuel particle under irradiation. Such a model, called PARFUME (PARticle Fuel ModEl), is being developed at the Idaho National Engineering and Environmental Laboratory. PARFUME is based on multi-dimensional finite element modeling of TRISO-coated gas reactor fuel. The goal is to represent all potential failure mechanisms and to incorporate the statistical nature of the fuel. The model is currently focused on carbide, oxide nd oxycarbide uranium fuel kernels, while the coating layers are the classical IPyC/SiC/OPyC. This paper reviews the current status of the mechanical aspects of the model and presents results of calculations for irradiations from the New Production Modular High Temperature Gas Reactor program.

  9. SP-100 coated-particle fuel development. Phase I. Final report

    SciTech Connect

    Not Available

    1983-03-01

    This document is the final report of Phase I of the SP-100 Coated-Particle Fuel Development Program conducted by GA Technologies Inc. for the US Department of Energy under contract DE-AT03-82SF11690. The general objective of the study conducted between September and December 1982 was to evaluate coated-particle type fuel as an alternate or backup fuel to the UO/sub 2/ tile-and-fin arrangement currently incorporated into the reference design of the SP-100 reactor core. This report presents and discusses the following topics in the order listed: the need for an alternative fuel for the SP-100 nuclear reactor; an abbreviated description of the reference and coated-particle fuel module concepts; the bases and results of the study and analysis leading to the preliminary design of a coated particle suitable for the SP-100 space power reactor; incorporation of the fuel particles into compacts and heat-pipe-cooled modules; initial efforts and plans to fabricate coated-particle fuel and fuel compacts; the design and performance of the proposed alternative core relative that of the reference fuel; and a summary of critical issues and conclusions consistent with the level of effort and duration of the study.

  10. Current Development Status of a Particle Size Analyzer for Coated Particle Fuel

    SciTech Connect

    Nelson, Andrew T; Hunn, John D; Karnowski, Thomas Paul

    2007-08-01

    Work was performed to develop a prototype Particle Size Analyzer (PSA) for application to coated particle fuel characterization. This system was based on a light obscuration method and targeted towards high throughput analysis. Although never matured to the point of replacing existing lower throughput optical microscopy shadowgraph methods, the system was successfully applied to automating the counting of large particle samples for increased accuracy in calculating mean particle properties based on measurements of multiparticle samples. The measurement of particle size with the PSA was compared to current shadowgraph techniques and found to result in considerably greater throughput at the cost of larger measurement uncertainty. The current algorithm used by the PSA is more sensitive to particle shape and this is a likely cause of the greater uncertainty when attempting to measure average particle diameter. The use of the PSA to measure particle shape will require further development. Particle transport through the PSA and stability of the light source/detector are key elements in the successful application of this technique. A number of system pitfalls were studied and addressed.

  11. Coated Particle and Deep Burn Fuels Monthly Highlights December 2010

    SciTech Connect

    Snead, Lance Lewis; Bell, Gary L; Besmann, Theodore M

    2011-01-01

    During FY 2011 the CP & DB Program will report Highlights on a monthly basis, but will no longer produce Quarterly Progress Reports. Technical details that were previously included in the quarterly reports will be included in the appropriate Milestone Reports that are submitted to FCRD Program Management. These reports will also be uploaded to the Deep Burn website. The Monthly Highlights report for November 2010, ORNL/TM-2010/323, was distributed to program participants on December 9, 2010. The final Quarterly for FY 2010, Deep Burn Program Quarterly Report for July - September 2010, ORNL/TM-2010/301, was announced to program participants and posted to the website on December 28, 2010. This report discusses the following: (1) Thermochemical Data and Model Development - (a) Thermochemical Modeling, (b) Core Design Optimization in the HTR (high temperature helium-cooled reactor) Pebble Bed Design (INL), (c) Radiation Damage and Properties; (2) TRISO (tri-structural isotropic) Development - (a) TRU (transuranic elements) Kernel Development, (b) Coating Development; (3) LWR Fully Ceramic Fuel - (a) FCM Fabrication Development, (b) FCM Irradiation Testing (ORNL); (4) Fuel Performance and Analytical Analysis - Fuel Performance Modeling (ORNL).

  12. Calculating Failure Probabilities for TRISO-coated Fuel Particles using an Integral Formulation

    SciTech Connect

    Gregory K. Miller; John T. maki; Darrell L. Knudsen; David A. Petti

    2010-04-01

    The fundamental design for a gas-cooled reactor relies on the safe behavior of the coated particle fuel. The coating layers surrounding the fuel kernels in these spherical particles, termed the TRISO coating, act as a pressure vessel that retains fission products. The quality of the fuel reflects the number of particle failures that occur during reactor operation, where failed particles become a source for fission products that can then diffuse through the fuel element matrix. The failure probability for any batch of particles, which has traditionally been calculated using the Monte Carlo method, depends on statistical variations in design parameters and on variations in the strengths of coating layers among particles in the batch. An alternative approach to calculating failure probabilities is developed herein that uses direct numerical integration of a failure probability integral. Because this is a multiple integral where the statistically varying parameters become integration variables, a fast numerical integration approach is also developed. In sample cases analyzed involving multiple failure mechanisms, results from the integration methods agree closely with Monte Carlo results. Additionally, the fast integration approach, particularly, is shown to significantly improve efficiency of failure probability calculations. These integration methods have been implemented in the PARFUME fuel performance code along with the Monte Carlo method, where each serves to verify accuracy of the others.

  13. Performance analysis of coated 238PuO2 fuel particles compact for radioisotope heater units

    NASA Astrophysics Data System (ADS)

    Tournier, Jean-Michel; El-Genk, Mohamed S.

    2000-01-01

    A fuel form consisting of coated plutonia fuel particles dispersed in a graphite matrix is being investigated for use in Radioisotope Heater Units (RHUs). The fuel particles consist of a 238PuO2 kernel (300-1200 μm in diameter), a 5-μm PyC inner coating and a ZrC outer coating (>=10 μm). The latter, an extremely strong material at high temperatures, serves as a pressure vessel for maintaining the integrity of the fuel particle and containing the helium generated by radioactive decay. Parametric analyses compared the thermal powers of the coated particle fuel compact (CPFC) RHU and LWRHU. Both utilize Fine-Weave Pierced Fabric (FWPF) aeroshell and PyC insulation sleeves. During normal operation, the fuel temperature is ~800 K, but could reach as much as 1723 K during an accidental re-entry heating. Assuming full helium release, a single-size particle (500 μm) fuel compact would maintain its integrity at a temperature of 1723 K, after 10 years storage time before launch. When replacing the LWRHU fuel pellet, Pt-alloy clad and inner PyC insulation sleeve with CPFC, the calculated thermal power of the CPFC-RHU is 1.5, 2.3 and 2.4 times that of LWRHU, for 100%, 10%, and 5% helium release, respectively, with little change in total mass. A fuel compact using binary-size particles (300 and 1200 μm diameters) would deliver 15% more thermal power. A one-dimensional, transient thermal analysis of the CPFC-RHU showed that during accidental re-entry the maximum fuel temperature in the CPFC would be 1734 K. .

  14. Coated particle fuel for radioisotope power systems (RPSs) and radioisotope heater units (RHUs)

    NASA Astrophysics Data System (ADS)

    Sholtis, Joseph A.; Lipinski, Ronald J.; El-Genk, Mohamed S.

    1999-01-01

    Coated particle fuel offers great promise for advanced radioisotope power systems (RPSs) and radioisotope heater units (RHUs) being pursued for future U.S. solar system exploration missions. Potential benefits of this fuel include improved design flexibility and materials compatibility, enhanced safety and performance, and reduced specific mass and volume. This paper describes and discusses coated particle fuel, with emphasis on its applicability, attributes, and potential benefits to future RPSs and RHUs. Additionally, this paper identifies further analyses and verification testing that should be conducted before a commitment is made to fully develop this fuel. Efforts to date indicate there is every reason to believe that the potential benefits of coated particle fuel to future RPSs and RHUs can be demonstrated with a modest, phased analytical and verification test effort. Thus, developmental risk appears minimal, while the potential benefits are substantial. If coated particle fuel is pursued and ultimately developed successfully, it could revolutionize the design and space use of future RPSs and RHUs.

  15. Stress Analysis of Coated Particle Fuel in the Deep-Burn Pebble Bed Reactor Design

    SciTech Connect

    B. Boer; A. M. Ougouag

    2010-05-01

    High fuel temperatures and resulting fuel particle coating stresses can be expected in a Pu and minor actinide fueled Pebble Bed Modular Reactor (400 MWth) design as compared to the ’standard’ UO2 fueled core. The high discharge burnup aimed for in this Deep-Burn design results in increased power and temperature peaking in the pebble bed near the inner and outer reflector. Furthermore, the pebble power in a multi-pass in-core pebble recycling scheme is relatively high for pebbles that make their first core pass. This might result in an increase of the mechanical failure of the coatings, which serve as the containment of radioactive fission products in the PBMR design. To investigate the integrity of the particle fuel coatings as a function of the irradiation time (i.e. burnup), core position and during a Loss Of Forced Cooling (LOFC) incident the PArticle STress Analysis code (PASTA) has been coupled to the PEBBED code for neutronics, thermal-hydraulics and depletion analysis of the core. Two deep burn fuel types (Pu with or without initial MA fuel content) have been investigated with the new code system for normal and transient conditions including the effect of the statistical variation of thickness of the coating layers.

  16. Thermo-Mechanical Analysis of Coated Particle Fuel Experiencing a Fast Control Rod Ejection Transient

    SciTech Connect

    Ortensi, J.; Brian Boer; Abderrafi M. Ougouag

    2010-10-01

    A rapid increase of the temperature and the mechanical stress is expected in TRISO coated particle fuel that experiences a fast Total Control Rod Ejection (CRE) transient event. During this event the reactor power in the pebble bed core increases significantly for a short time interval. The power is deposited instantly and locally in the fuel kernel. This could result in a rapid increase of the pressure in the buffer layer of the coated fuel particle and, consequently, in an increase of the coating stresses. These stresses determine the mechanical failure probability of the coatings, which serve as the containment of radioactive fission products in the Pebble Bed Reactor (PBR). A new calculation procedure has been implemented at the Idaho National Laboratory (INL), which analyzes the transient fuel performance behavior of TRISO fuel particles in PBRs. This early capability can easily be extended to prismatic designs, given the availability of neutronic and thermal-fluid solvers. The full-core coupled neutronic and thermal-fluid analysis has been modeled with CYNOD-THERMIX. The temperature fields for the fuel kernel and the particle coatings, as well as the gas pressures in the buffer layer, are calculated with the THETRIS module explicitly during the transient calculation. Results from this module are part of the feedback loop within the neutronic-thermal fluid iterations performed for each time step. The temperature and internal pressure values for each pebble type in each region of the core are then input to the PArticle STress Analysis (PASTA) code, which determines the particle coating stresses and the fraction of failed particles. This paper presents an investigation of a Total Control Rod Ejection (TCRE) incident in the 400 MWth Pebble Bed Modular reactor design using the above described calculation procedure. The transient corresponds to a reactivity insertion of $3 (~2000 pcm) reaching 35 times the nominal power in 0.5 seconds. For each position in the core

  17. In situ ceramic layer growth on coated fuel particles dispersed in a zirconium metal matrix

    SciTech Connect

    Terrani, Kurt A; Silva, G W Chinthaka M; Kiggans, Jim; Cai, Zhonghou; Shin, Dongwon; Snead, Lance Lewis

    2013-01-01

    The extent and nature of the chemical interaction between the outermost coating layer of coated fuel particles embedded in zirconium metal during fabrication of metal matrix microencapsulated fuels was examined. Various particles with outermost coating layers of pyrocarbon, SiC, and ZrC have been investigated in this study. ZrC-Zr interaction was least substantial while PyC-Zr reaction can be exploited to produce a ZrC layer at the interface in an in situ manner. The thickness of the ZrC layer in the latter case can be controlled by adjusting the time and temperature during processing. The kinetics of ZrC layer growth is significantly faster from what is predicted using literature carbon diffusivity data in ZrC. SiC-Zr interaction is more complex and results in formation of various chemical phases in a layered aggregate morphology at the interface.

  18. In situ ceramic layer growth on coated fuel particles dispersed in a zirconium metal matrix

    NASA Astrophysics Data System (ADS)

    Terrani, K. A.; Silva, C. M.; Kiggans, J. O.; Cai, Z.; Shin, D.; Snead, L. L.

    2013-06-01

    The extent and nature of the chemical interaction between the outermost coating layer of coated fuel particles embedded in zirconium metal during fabrication of metal matrix microencapsulated fuels were examined. Various particles with outermost coating layers of pyrocarbon, SiC, and ZrC have been investigated in this study. ZrC-Zr interaction was the least substantial, while the PyC-Zr reaction can be exploited to produce a ZrC layer at the interface in an in situ manner. The thickness of the ZrC layer in the latter case can be controlled by adjusting the time and temperature during processing. The kinetics of ZrC layer growth is significantly faster from what is predicted using literature carbon diffusivity data in ZrC. SiC-Zr interaction is more complex and results in formation of various chemical phases in a layered aggregate morphology at the interface.

  19. Evaluation of design parameters for TRISO-coated fuel particles to establish manufacturing critical limits using PARFUME

    SciTech Connect

    Skerjanc, William F.; Maki, John T.; Collin, Blaise P.; Petti, David A.

    2015-12-02

    The success of modular high temperature gas-cooled reactors is highly dependent on the performance of the tristructural-isotopic (TRISO) coated fuel particle and the quality to which it can be manufactured. During irradiation, TRISO-coated fuel particles act as a pressure vessel to contain fission gas and mitigate the diffusion of fission products to the coolant boundary. The fuel specifications place limits on key attributes to minimize fuel particle failure under irradiation and postulated accident conditions. PARFUME (an integrated mechanistic coated particle fuel performance code developed at the Idaho National Laboratory) was used to calculate fuel particle failure probabilities. By systematically varying key TRISO-coated particle attributes, failure probability functions were developed to understand how each attribute contributes to fuel particle failure. Critical manufacturing limits were calculated for the key attributes of a low enriched TRISO-coated nuclear fuel particle with a kernel diameter of 425 μm. As a result, these critical manufacturing limits identify ranges beyond where an increase in fuel particle failure probability is expected to occur.

  20. Evaluation of design parameters for TRISO-coated fuel particles to establish manufacturing critical limits using PARFUME

    DOE PAGESBeta

    Skerjanc, William F.; Maki, John T.; Collin, Blaise P.; Petti, David A.

    2015-12-02

    The success of modular high temperature gas-cooled reactors is highly dependent on the performance of the tristructural-isotopic (TRISO) coated fuel particle and the quality to which it can be manufactured. During irradiation, TRISO-coated fuel particles act as a pressure vessel to contain fission gas and mitigate the diffusion of fission products to the coolant boundary. The fuel specifications place limits on key attributes to minimize fuel particle failure under irradiation and postulated accident conditions. PARFUME (an integrated mechanistic coated particle fuel performance code developed at the Idaho National Laboratory) was used to calculate fuel particle failure probabilities. By systematically varyingmore » key TRISO-coated particle attributes, failure probability functions were developed to understand how each attribute contributes to fuel particle failure. Critical manufacturing limits were calculated for the key attributes of a low enriched TRISO-coated nuclear fuel particle with a kernel diameter of 425 μm. As a result, these critical manufacturing limits identify ranges beyond where an increase in fuel particle failure probability is expected to occur.« less

  1. Evaluation of design parameters for TRISO-coated fuel particles to establish manufacturing critical limits using PARFUME

    NASA Astrophysics Data System (ADS)

    Skerjanc, William F.; Maki, John T.; Collin, Blaise P.; Petti, David A.

    2016-02-01

    The success of modular high temperature gas-cooled reactors is highly dependent on the performance of the tristructural-isotopic (TRISO) coated fuel particle and the quality to which it can be manufactured. During irradiation, TRISO-coated fuel particles act as a pressure vessel to contain fission gas and mitigate the diffusion of fission products to the coolant boundary. The fuel specifications place limits on key attributes to minimize fuel particle failure under irradiation and postulated accident conditions. PARFUME (an integrated mechanistic coated particle fuel performance code developed at the Idaho National Laboratory) was used to calculate fuel particle failure probabilities. By systematically varying key TRISO-coated particle attributes, failure probability functions were developed to understand how each attribute contributes to fuel particle failure. Critical manufacturing limits were calculated for the key attributes of a low enriched TRISO-coated nuclear fuel particle with a kernel diameter of 425 μm. These critical manufacturing limits identify ranges beyond where an increase in fuel particle failure probability is expected to occur.

  2. Experimental test plan: USDOE/JAERI collaborative program for the coated particle fuel performance test

    SciTech Connect

    Kania, M.J.; Fukuda, K.

    1989-12-01

    This document describes the coated-particle fuel performance test agreed to under Annex 2 of the arrangement between the US Department of Energy and the Japan Atomic Energy Research Institute on cooperation in research and development regarding high-temperature gas-cooled reactors (HTGRs). The test will evaluate the behavior of reference fuel compacts containing coated-particle fuels fabricated according to the specifications for the US Modular HTGR and the Japanese High-Temperature Engineering Test Reactor (HTTR) concepts. Two experimental capsules, HRB-21 and HRB-22, are being tested. Capsule HRB-21 contains only US reference fuel, and HRB-22 contains only JAERI reference fuel. Both capsules will be irradiated in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). Capsule HRB-21 will be operated at a mean volumetric fuel temperature of 975{degrees}C and will achieve a peak fissile burnup of 26% fissions per initial metal atom (FIMA) and a fast fluence of {le}4.5 {times} 10{sup 25} neutrons/m{sup 2}. Capsule HRB-22 will be operated at a mean centerline fuel temperature of 1250 to 1300{degrees}C and will achieve a peak fissile burnup of 5.5% FIMA and a fast fluence of 1.7 {times} 10{sup 25} neutrons/m{sup 2}. Performance of the fuels during irradiation will be closely monitored using on-line fission gas surveillance. Following irradiation, both capsules will undergo detailed examinations and core heatup simulation testing. Results from in-reactor monitoring and postirradiation testing will be analyzed to comparatively assess US and Japanese coated-particle fuel performance. 3 refs., 9 figs., 10 tabs.

  3. Coated particle fuel for radioisotope power systems and heater units: status and future research needs

    NASA Astrophysics Data System (ADS)

    El-Genk, Mohamed S.; Tournier, Jean-Michel; Sholtis, Joseph A.; Lipinski, Ronald J.

    2000-01-01

    Coated particle fuel has been proposed recently for use in Radioisotope Power Systems (RPSs) and Radioisotope Heater Units (RHUs) for a variety of space missions requiring power levels from mWs to 10's or even hundreds of Watts. It can be made into different shapes and sizes of solid compacts, heating tapes, or paints. Using a conservative design approach, this fuel form could increase by 2.3-2.4 times the thermal power output of a LWRHU, while offering promise of enhanced safety. These performance figures are based on using single-size (500 μm) compacts of ZrC coated 238PuO2 kernels and assuming 10% and 5% He release, respectively, at 1723 K, following 10 years of storage. Using binary-size (300 and 1200 μm) fuel kernels in the compact increases the thermal power output by an additional 15%. 238PuO2 fuel kernels are intentionally sized (>=300 μm in diameter) to prevent any adverse radiological effects. They are non-respirable and non-inhalable and, if ingested, would simply be excreted with no radiological effects. The 238PuO2 fuel kernels are contained within a strong ZrC coating, which is designed to fully retain the fuel and the helium gas. Helium retention in large grain (>=300 μm) granular and polycrystalline fuel kernels is possible even at high temperatures (>1700 K). The former could be fabricated using binderless agglomeration or similar processes, while the latter could be fabricated using Sol-Gel or thermal plasma processes, with potentially less radioactive waste and fabrication contamination. In addition to summarizing the results of a recent effort investigating the performance of coated fuel particle compact (CPFC) and helium gas release, this paper identifies and discusses future research and testing needs. .

  4. Coated Particles Fuel Compact-General Purpose Heat Source for Advanced Radioisotope Power Systems

    NASA Astrophysics Data System (ADS)

    El-Genk, Mohamed S.; Tournier, Jean-Michel

    2003-01-01

    Coated Particles Fuel Compacts (CPFC) have recently been shown to offer performance advantage for use in Radioisotope Heater Units (RHUs) and design flexibility for integrating at high thermal efficiency with Stirling Engine converters, currently being considered for 100 We. Advanced Radioisotope Power Systems (ARPS). The particles in the compact consist of 238PuO2 fuel kernels with 5-μm thick PyC inner coating and a strong ZrC outer coating, whose thickness depends on the maximum fuel temperature during reentry, the fuel kernel diameter, and the fraction of helium gas released from the kernels and fully contained by the ZrC coating. In addition to containing the helium generated by radioactive decay of 238Pu for up to 10 years before launch and 10-15 years mission lifetime, the kernels are intentionally sized (>= 300 μm in diameter) to prevent any adverse radiological effects on reentry. This paper investigates the advantage of replacing the four iridium-clad 238PuO2 fuel pellets, the two floating graphite membranes, and the two graphite impact shells in current State-Of-The-Art (SOA) General Purpose Heat Source (GPHS) with CPFC. The total mass, thermal power, and specific power of the CPFC-GPHS are calculated as functions of the helium release fraction from the fuel kernels and maximum fuel temperature during reentry from 1500 K to 2400 K. For the same total mass and volume as SOA GPHS, the generated thermal power by single-size particles CPFC-GPHS is 260 W at Beginning-Of-Mission (BOM), versus 231 W for the GPHS. For an additional 10% increase in total mass, the CPFC-GPHS could generate 340 W BOM; 48% higher than SOA GPHS. The corresponding specific thermal power is 214 W/kg, versus 160 W/kg for SOA GPHS; a 34% increase. Therefore, for the same thermal power, the CPFC-GPHS is lighter than SOA GPHS, while it uses the same amount of 238PuO2 fuel and same aeroshell. For the same helium release fraction and fuel temperature, binary-size particles CPFC-GPHS could

  5. The Challenges Associated with High Burnup and High Temperature for UO2 TRISO-Coated Particle Fuel

    SciTech Connect

    David Petti; John Maki

    2005-02-01

    The fuel service conditions for the DOE Next Generation Nuclear Plant (NGNP) will be challenging. All major fuel related design parameters (burnup, temperature, fast neutron fluence, power density, particle packing fraction) exceed the values that were qualified in the successful German UO2 TRISO-coated particle fuel development program in the 1980s. While TRISO-coated particle fuel has been irradiated at NGNP relevant levels for two or three of the design parameters, no data exist for TRISO-coated particle fuel for all five parameters simultaneously. Of particular concern are the high burnup and high temperatures expected in the NGNP. In this paper, where possible, we evaluate the challenges associated with high burnup and high temperature quantitatively by examining the performance of the fuel in terms of different known failure mechanisms. Potential design solutions to ameliorate the negative effects of high burnup and high temperature are also discussed.

  6. Fission product Pd-SiC interaction in irradiated coated particle fuels

    SciTech Connect

    Tiegs, T.N.

    1980-04-01

    Silicon carbide is the main barrier to fission product release from coated particle fuels. Consequently, degradation of the SiC must be minimized. Electron microprobe analysis has identified that palladium causes corrosion of the SiC in irradiated coated particles. Further ceramographic and electron microprobe examinations on irradiated particles with kernels ranging in composition from UO/sub 2/ to UC/sub 2/, including PuO/sub 2 -x/ and mixed (Th, Pu) oxides, and in enrichment from 0.7 to 93.0% /sup 235/U revealed that temperature is the major factor affecting the penetration rate of SiC by Pd. The effects of kernel composition, Pd concentration, other fission products, and SiC properties are secondary.

  7. Device for fracturing silicon-carbide coatings on nuclear-fuel particles

    DOEpatents

    Turner, L.J.; Willey, M.G.; Tiegs, S.M.; Van Cleve, J.E. Jr.

    This invention is a device for fracturing particles. It is designed especially for use in hot cells designed for the handling of radioactive materials. In a typical application, the device is used to fracture a hard silicon-carbide coating present on carbon-matrix microspheres containing nuclear-fuel materials, such as uranium or thorium compounds. To promote remote control and facilitate maintenance, the particle breaker is pneumatically operated and contains no moving parts. It includes means for serially entraining the entrained particles on an anvil housed in a leak-tight chamber. The flow rate of the gas is at a value effecting fracture of the particles; preferably, it is at a value fracturing them into product particulates of fluidizable size. The chamber is provided with an outlet passage whose cross-sectional area decreases in the direction away from the chamber. The outlet is connected tangentially to a vertically oriented vortex-flow separator for recovering the product particulates entrained in the gas outflow from the chamber. The invention can be used on a batch or continuous basis to fracture the silicon-carbide coatings on virtually all of the particles fed thereto.

  8. Method for fracturing silicon-carbide coatings on nuclear-fuel particles

    DOEpatents

    Turner, Lloyd J.; Willey, Melvin G.; Tiegs, Sue M.; Van Cleve, Jr., John E.

    1982-01-01

    This invention is a device for fracturing particles. It is designed especially for use in "hot cells" designed for the handling of radioactive materials. In a typical application, the device is used to fracture a hard silicon-carbide coating present on carbon-matrix microspheres containing nuclear-fuel material, such as uranium or thorium compounds. To promote remote control and facilitate maintenance, the particle breaker is pneumatically operated and contains no moving parts. It includes means for serially entraining the entrained particles on an anvil housed in a leak-tight chamber. The flow rate of the gas is at a value effecting fracture of the particles; preferably, it is at a value fracturing them into product particulates of fluidizable size. The chamber is provided with an outlet passage whose cross-sectional area decreases in the direction away from the chamber. The outlet is connected tangentially to a vertically oriented vortex-flow separator for recovering the product particulates entrained in the gas outflow from the chamber. The invention can be used on a batch or continuous basis to fracture the silicon-carbide coatings on virtually all of the particles fed thereto.

  9. Fluoride-Salt-Cooled High-Temperature Reactor (FHR) with Silicon-Carbide-Matrix Coated-Particle Fuel

    SciTech Connect

    Forsberg, C. W.; Terrani, Kurt A; Snead, Lance Lewis; Katoh, Yutai

    2012-01-01

    The FHR is a new reactor concept that uses coated-particle fuel and a low-pressure liquid-salt coolant. Its neutronics are similar to a high-temperature gas-cooled reactor (HTGR). The power density is 5 to 10 times higher because of the superior cooling properties of liquids versus gases. The leading candidate coolant salt is a mixture of {sup 7}LiF and BeF{sub 2} (FLiBe) possessing a boiling point above 1300 C and the figure of merit {rho}C{sub p} (volumetric heat capacity) for the salt slightly superior to water. Studies are underway to define a near-term base-line concept while understanding longer-term options. Near-term options use graphite-matrix coated-particle fuel where the graphite is both a structural component and the primary neutron moderator. It is the same basic fuel used in HTGRs. The fuel can take several geometric forms with a pebble bed being the leading contender. Recent work on silicon-carbide-matrix (SiCm) coated-particle fuel may create a second longer-term fuel option. SiCm coated-particle fuels are currently being investigated for use in light-water reactors. The replacement of the graphite matrix with a SiCm creates a new family of fuels. The first motivation behind the effort is to take advantage of the superior radiation resistance of SiC compared to graphite in order to provide a stable matrix for hosting coated fuel particles. The second motivation is a much more rugged fuel under accident, repository, and other conditions.

  10. Thermal conductivity mapping of pyrolytic carbon and silicon carbide coatings on simulated fuel particles by time-domain thermoreflectance

    NASA Astrophysics Data System (ADS)

    López-Honorato, E.; Chiritescu, C.; Xiao, P.; Cahill, David G.; Marsh, G.; Abram, T. J.

    2008-08-01

    Thermal conductivity of pyrolytic carbon and silicon carbide coatings on spherical particles has been mapped using time-domain thermoreflectance. The thermal conductivities measured for pyrolytic carbon ranged between 3.4 and 13.5 W/m K. The effect of porosity, pore-size distribution, anisotropy, in-plane disorder and domain sizes is discussed. A thermal conductivity of 168 W/m K was obtained for SiC. Mapping of the thermal conductivity of coated fuel particles provides useful data for modeling fuel performance during the operation of nuclear reactors.

  11. Key Differences in the Fabrication, Irradiation, and Safety Testing of U.S. and German TRISO-coated Particle Fuel and Their Implications on Fuel Performance

    SciTech Connect

    Petti, David Andrew; Maki, John Thomas; Buongiorno, Jacopo; Hobbins, Richard Redfield

    2002-06-01

    High temperature gas reactor technology is achieving a renaissance around the world. This technology relies on high quality production and performance of coated particle fuel. Historically, the irradiation performance of TRISO-coated gas reactor particle fuel in Germany has been superior to that in the United States. German fuel generally displayed in-pile gas release values that were three orders of magnitude lower than U.S. fuel. Thus, we have critically examined the TRISO-coated fuel fabrication processes in the U.S. and Germany and the associated irradiation database with a goal of understanding why the German fuel behaves acceptably, why the U.S. fuel has not faired as well, and what process/ production parameters impart the reliable performance to this fuel form. The postirradiation examination results are also reviewed to identify failure mechanisms that may be the cause of the poorer U.S. irradiation performance. This comparison will help determine the roles that particle fuel process/product attributes and irradiation conditions (burnup, fast neutron fluence, temperature, and degree of acceleration) have on the behavior of the fuel during irradiation and provide a more quantitative linkage between acceptable processing parameters, as-fabricated fuel properties and subsequent in-reactor performance.

  12. Uranium extraction from TRISO-coated fuel particles using supercritical CO2 containing tri-n-butyl phosphate.

    PubMed

    Zhu, Liyang; Duan, Wuhua; Xu, Jingming; Zhu, Yongjun

    2012-11-30

    High-temperature gas-cooled reactors (HTGRs) are advanced nuclear systems that will receive heavy use in the future. It is important to develop spent nuclear fuel reprocessing technologies for HTGR. A new method for recovering uranium from tristructural-isotropic (TRISO-) coated fuel particles with supercritical CO(2) containing tri-n-butyl phosphate (TBP) as a complexing agent was investigated. TRISO-coated fuel particles from HTGR fuel elements were first crushed to expose UO(2) pellet fuel kernels. The crushed TRISO-coated fuel particles were then treated under O(2) stream at 750°C, resulting in a mixture of U(3)O(8) powder and SiC shells. The conversion of U(3)O(8) into solid uranyl nitrate by its reaction with liquid N(2)O(4) in the presence of a small amount of water was carried out. Complete conversion was achieved after 60 min of reaction at 80°C, whereas the SiC shells were not converted by N(2)O(4). Uranyl nitrate in the converted mixture was extracted with supercritical CO(2) containing TBP. The cumulative extraction efficiency was above 98% after 20 min of online extraction at 50°C and 25 MPa, whereas the SiC shells were not extracted by TBP. The results suggest an attractive strategy for reprocessing spent nuclear fuel from HTGR to minimize the generation of secondary radioactive waste.

  13. Nickel-Coated Aluminum Particles: A Promising Fuel for Mars Missions

    NASA Technical Reports Server (NTRS)

    Shafirovich, Evgeny; Varma, Arvind

    2004-01-01

    Combustion of metals in carbon dioxide is a promising source of energy for propulsion on Mars. This approach is based on the ability of some metals (e.g. Mg, Al) to burn in CO2 atmosphere and suggests use of the Martian carbon dioxide as an oxidizer in jet or rocket engines. Analysis shows that CO2/metal propulsion will reduce significantly the mass of propellant transported from Earth for long-range mobility on Mars and sample return missions. Recent calculations for the near-term missions indicate that a 200-kg ballistic hopper with CO2/metal rocket engines and a CO2 acquisition unit can perform 10-15 flights on Mars with the total range of 10-15 km, i.e. fulfill the exploration program typically assigned for a rover. Magnesium is currently recognized as a candidate fuel for such engines owing to easy ignition and fast burning in CO2. Aluminum may be more advantageous if a method for reducing its ignition temperature is found. Coating it by nickel is one such method. It is known that a thin nickel layer of nickel on the surface of aluminum particles can prevent their agglomeration and simultaneously facilitate their ignition, thus increasing the efficiency of aluminized propellants. Combustion of single Ni-coated Al particles in different gas environments (O2, CO2, air) was studied using electrodynamic levitation and laser ignition. It was shown that the combustion mechanisms depend on the ambient atmosphere. Combustion in CO2 is characterized by the smaller size and lower brightness of flame than in O2, and by phenomena such as micro-flashes and fragment ejection. The size and brightness of flame gradually decrease as the particle burns.

  14. Development of Improved Models and Designs for Coated-Particle Gas Reactor Fuels (I-NERI Annual Report)

    SciTech Connect

    Petti, David Andrew; Maki, John Thomas; Languille, Alain; Martin, Philippe; Ballinger, Ronald

    2002-11-01

    The objective of this INERI project is to develop improved fuel behavior models for gas reactor coated particle fuels and to develop improved coated-particle fuel designs that can be used reliably at very high burnups and potentially in fast gas-cooled reactors. Thermomechanical, thermophysical, and physiochemical material properties data were compiled by both the US and the French and preliminary assessments conducted. Comparison between U.S. and European data revealed many similarities and a few important differences. In all cases, the data needed for accurate fuel performance modeling of coated particle fuel at high burnup were lacking. The development of the INEEL fuel performance model, PARFUME, continued from earlier efforts. The statistical model being used to simulate the detailed finite element calculations is being upgraded and improved to allow for changes in fuel design attributes (e.g. thickness of layers, dimensions of kernel) as well as changes in important material properties to increase the flexibility of the code. In addition, modeling of other potentially important failure modes such as debonding and asphericity was started. A paper on the status of the model was presented at the HTR-2002 meeting in Petten, Netherlands in April 2002, and a paper on the statistical method was submitted to the Journal of Nuclear Material in September 2002. Benchmarking of the model against Japanese and an older DRAGON irradiation are planned. Preliminary calculations of the stresses in a coated particle have been calculated by the CEA using the ATLAS finite element model. This model and the material properties and constitutive relationships will be incorporated into a more general software platform termed Pleiades. Pleiades will be able to analyze different fuel forms at different scales (from particle to fuel body) and also handle the statistical variability in coated particle fuel. Diffusion couple experiments to study Ag and Pd transport through SiC were

  15. Method of evaluating the integrity of the outer carbon layer of triso-coated reactor fuel particles

    DOEpatents

    Caputo, Anthony J.; Costanzo, Dante A.; Lackey, Jr., Walter J.; Layton, Frank L.; Stinton, David P.

    1980-01-01

    This invention relates to a method for determining defective final layers of carbon on triso-coated fuel particles and the like. Samples of the particles are subjected to a high temperature treatment with gaseous chlorine and thereafter radiographed. The chlorine penetrates through any defective carbon layer and reacts with the underlying silicon carbide resulting in the volatilization of the silicon as SiCl.sub.4 leaving carbon as a porous layer. This porous carbon layer is easily detected by the radiography.

  16. Development of Improved Models and Designs for Coated-Particle Gas Reactor Fuels -- Final Report under the International Nuclear Energy Research Initiative (I-NERI)

    SciTech Connect

    Petti, David; Martin, Philippe; Phelip, Mayeul; Ballinger, Ronald

    2004-12-01

    The objective of this INERI project was to develop improved fuel behavior models for gas reactor coated-particle fuels and to explore improved coated-particle fuel designs that could be used reliably at very high burnups and potentially in gas-cooled fast reactors. Project participants included the Idaho National Engineering Laboratory (INEEL), Centre Étude Atomique (CEA), and the Massachusetts Institute of Technology (MIT). To accomplish the project objectives, work was organized into five tasks.

  17. Nickel-coated Aluminum Particles: A Promising Fuel for Mars Missions

    NASA Technical Reports Server (NTRS)

    Shafirovich, Evgeny; Varma, Arvind

    2004-01-01

    Combustion of metals in carbon dioxide is a promising source of energy for propulsion on Mars. This approach is based on the ability of some metals (e.g. Mg, Al) to burn in CO2 atmosphere and suggests use of the Martian carbon dioxide as an oxidizer in jet or rocket engines. Analysis shows that CO2/metal propulsion will reduce significantly the mass of propellant transported from Earth for long-range mobility on Mars and sample return missions. Recent calculations for the near-term missions indicate that a 200-kg ballistic hopper with CO2/metal rocket engines and a CO2 acquisition unit can perform 10-15 flights on Mars with the total range of 10-15 km, i.e. fulfill the exploration program typically assigned for a rover. Magnesium is currently recognized as a candidate fuel for such engines owing to easy ignition and fast burning in CO2. Aluminum may be more advantageous if a method for reducing its ignition temperature is found. Coating it by nickel is one such method. It is known that a thin nickel layer of nickel on the surface of aluminum particles can prevent their agglomeration and simultaneously facilitate their ignition, thus increasing the efficiency of aluminized propellants.

  18. First elevated-temperature performance testing of coated particle fuel compacts from the AGR-1 irradiation experiment

    SciTech Connect

    Charles A. Baldwin; John D. Hunn; Robert N. Morris; Fred C. Montgomery; Chinthaka M. Silva; Paul A. Demkowicz

    2014-05-01

    In the AGR-1 irradiation experiment, 72 coated-particle fuel compacts were taken to a peak burnup of 19.5% fissions per initial metal atom with no in-pile failures. This paper discusses the first post-irradiation test of these mixed uranium oxide/uranium carbide fuel compacts at elevated temperature to examine the fuel performance under a simulated depressurized conduction cooldown event. A compact was heated for 400 h at 1600 degrees C. Release of 85Kr was monitored throughout the furnace test as an indicator of coating failure, while other fission product releases from the compact were periodically measured by capturing them on exchangeable, water-cooled deposition cups. No coating failure was detected during the furnace test, and this result was verified by subsequent electrolytic deconsolidation and acid leaching of the compact, which showed that all SiC layers were still intact. However, the deposition cups recovered significant quantities of silver, europium, and strontium. Based on comparison of calculated compact inventories at the end of irradiation versus analysis of these fission products released to the deposition cups and furnace internals, the minimum estimated fractional losses from the compact during the furnace test were 1.9 x 10-2 for silver, 1.4 x 10-3 for europium, and 1.1 x 10-5 for strontium. Other post-irradiation examination of AGR-1 compacts indicates that similar fractions of europium and silver may have already been released by the intact coated particles during irradiation, and it is therefore likely that the detected fission products released from the compact in this 1600 degrees C furnace test were from residual fission products in the matrix. Gamma analysis of coated particles deconsolidated from the compact after the heating test revealed that silver content within each particle varied considerably; a result that is probably not related to the furnace test, because it has also been observed in other as-irradiated AGR-1 compacts. X

  19. Coated Particle Fuel and Deep Burn Program Monthly Highlights February 2011

    SciTech Connect

    Snead, Lance Lewis; Bell, Gary L; Besmann, Theodore M

    2011-03-01

    During FY 2011 the CP & DB Program will report Highlights on a monthly basis, but will no longer produce Quarterly Progress Reports. Technical details that were previously included in the quarterly reports will be included in the appropriate Milestone Reports that are submitted to FCRD Program Management. These reports will also be uploaded to the Deep Burn website. The Monthly Highlights report for January 2010, ORNL/TM-2011/30, was distributed to program participants on February 8, 2011. As reported previously, the final Quarterly for FY 2010, Deep Burn Program Quarterly Report for July - September 2010, ORNL/TM-2010/301, was announced to program participants and posted to the website on December 28, 2010. This report discusses the following: (1) Thermochemical Data and Model Development - (a) Thermochemical Modeling, (b) Actinide and Fission Product Transport, (c) Radiation Damage and Properties; (2) TRU (transuranic elements) TRISO (tri-structural isotropic) Development - (a) TRU Kernel Development, (b) Coating Development; (3) Advanced TRISO Applications - Metal Matrix Fuels for LWR; (4) LWR Fully Ceramic Fuel - (a) FCM Fabrication Development, (b) FCM Irradiation Testing; and (5) Fuel Performance and Analytical Analysis - Fuel Performance Modeling.

  20. Coated Particle Fuel and Deep Burn Program Monthly Highlights January 2011

    SciTech Connect

    Snead, Lance Lewis; Bell, Gary L; Besmann, Theodore M

    2011-02-01

    During FY 2011 the CP & DB Program will report Highlights on a monthly basis, but will no longer produce Quarterly Progress Reports. Technical details that were previously included in the quarterly reports will be included in the appropriate Milestone Reports that are submitted to FCRD Program Management. These reports will also be uploaded to the Deep Burn website. The Monthly Highlights report for December 2010, ORNL/TM-2011/10, was distributed to program participants on January 12, 2011. As reported last month, the final Quarterly for FY 2010, Deep Burn Program Quarterly Report for July - September 2010, ORNL/TM-2010/301, was announced to program participants and posted to the website on December 28, 2010. This report discusses the following: (1) Thermochemical Data and Model Development - (a) Thermochemical Modeling, (b) Actinide and Fission Product Transport, (c) Radiation Damage and Properties; (2) TRU (transuranic elements) TRISO (tri-structural isotropic) Development - (a) TRU Kernel Development, (b) Coating Development; (3) Advanced TRISO Applications - Metal Matrix Fuels for LWR; (4) LWR Fully Ceramic Fuel - (a) FCM Fabrication Development, (b) FCM Irradiation Testing; (5) Fuel Performance and Analytical Analysis - Fuel Performance Modeling.

  1. Coated Particle Fuel and Deep Burn Program Monthly Highlights March 2011

    SciTech Connect

    Snead, Lance Lewis; Bell, Gary L; Besmann, Theodore M

    2011-04-01

    During FY 2011 the CP & DB Program will report Highlights on a monthly basis, but will no longer produce Quarterly Progress Reports. Technical details that were previously included in the quarterly reports will be included in the appropriate Milestone Reports that are submitted to FCRD Program Management. These reports will also be uploaded to the Deep Burn website. The Monthly Highlights report for February 2011, ORNL/TM-2011/71, was distributed to program participants on March 8, 2011. As reported previously, the final Quarterly for FY 2010, Deep Burn Program Quarterly Report for July - September 2010, ORNL/TM-2010/301, was announced to program participants and posted to the website on December 28, 2010. This report discusses the following: (1) Thermochemical Data and Model Development - (a) Thermochemical Modeling, (b) Thermomechanical Behavior, (c) Actinide and Fission Product Transport, (d) Radiation Damage and Properties; (2) TRU (transuranic elements) TRISO (tri-structural isotropic) Development - (a) TRU Kernel Development, (b) Coating Development; (3) Advanced TRISO Applications - Metal Matrix Fuels for LWR; (4) LWR Fully Ceramic Fuel - (a) FCM Fabrication Development, (b) FCM Irradiation Testing; and (5) Fuel Performance and Analytical Analysis - Fuel Performance Modeling.

  2. Coated Particle Fuel and Deep Burn Program Monthly Highlights June 2011

    SciTech Connect

    Snead, Lance Lewis; Bell, Gary L; Besmann, Theodore M

    2011-07-01

    During FY 2011 the CP & DB Program will report Highlights on a monthly basis, but will no longer produce Quarterly Progress Reports. Technical details that were previously included in the quarterly reports will be included in the appropriate Milestone Reports that are submitted to FCRD Program Management. These reports will also be uploaded to the Deep Burn website. The Monthly Highlights report for May 2011, ORNL/TM-2011/126, was distributed to program participants on June 9, 2011. As reported previously, the final Quarterly for FY 2010, Deep Burn Program Quarterly Report for July - September 2010, ORNL/TM-2010/301, was announced to program participants and posted to the website on December 28, 2010. This report discusses the following: (1) Fuel Performance Modeling - Fuel Performance Analysis; (2) Thermochemical Data and Model Development - (a) Thermochemical Behavior, (b) Thermomechanical Modeling, (c) Actinide and Fission Product Transport; (3) TRU (transuranic elements) TRISO (tri-structural isotropic) Development - (a) TRU Kernel Development, (b) Coating Development; and (4) LWR Fully Ceramic Fuel - (a) FCM Fabrication Development, (b) FCM Irradiation Testing.

  3. Coated Particle Fuel and Deep Burn Program Monthly Highlights April 2011

    SciTech Connect

    Snead, Lance Lewis; Bell, Gary L; Besmann, Theodore M

    2011-05-01

    The baseline change proposal BCP-FCRD-11026 submitted to change the due date for M21AF080202 'Demonstrate fabrication of Transuranic kernels of Plutonium-239/3.5at%Neptunium-237 using newly installed glove box facilities in ORNL 7930 hot cell complex' from 4/25/11 to 3/30/12 was approved this month. During FY 2011 the CP & DB Program will report Highlights on a monthly basis, but will no longer produce Quarterly Progress Reports. Technical details that were previously included in the quarterly reports will be included in the appropriate Milestone Reports that are submitted to FCRD Program Management. These reports will also be uploaded to the Deep Burn website. The Monthly Highlights report for March 2011, ORNL/TM-2011/96, was distributed to program participants on April 8, 2011. As reported previously, the final Quarterly for FY 2010, Deep Burn Program Quarterly Report for July - September 2010, ORNL/TM-2010/301, was announced to program participants and posted to the website on December 28, 2010. This report discusses the following: (1) Thermochemical Data and Model Development - (a) Thermochemical Modeling, (b) Thermomechanical Behavior, (c) Actinide and Fission Product Transport, (d) Radiation Damage and Properties; (2) TRU (transuranic elements) TRISO (tri-structural isotropic) Development - (a) TRU Kernel Development, (b) Coating Development; (3) Advanced TRISO Applications - Metal Matrix Fuels for LWR; (4) LWR Fully Ceramic Fuel - (a) FCM Fabrication Development, (b) FCM Irradiation Testing; (5) Fuel Performance and Analytical Analysis - Fuel Performance Modeling; and (6) ZrC Properties and Handbook - Properties of ZrC.

  4. Automatic Characterization of Cross-section Coated Particle Nuclear Fuel using Greedy Coupled Bayesian Snakes

    SciTech Connect

    Price, Jeffery R; Aykac, Deniz; Hunn, John D; Kercher, Andrew K

    2007-01-01

    We describe new image analysis developments in support of the U.S. Department of Energy's (DOE) Advanced Gas Reactor (AGR) Fuel Development and Qualification Program. We previously reported a non-iterative, Bayesian approach for locating the boundaries of different particle layers in cross-sectional imagery. That method, however, had to be initialized by manual preprocessing where a user must select two points in each image, one indicating the particle center and the other indicating the first layer interface. Here, we describe a technique designed to eliminate the manual preprocessing and provide full automation. With a low resolution image, we use 'EdgeFlow' to approximate the layer boundaries with circular templates. Multiple snakes are initialized to these circles and deformed using a greedy Bayesian strategy that incorporates coupling terms as well as a priori information on the layer thicknesses and relative contrast. We show results indicating the effectiveness of the proposed method.

  5. A roadmap for the development and validation of coated particle fuel for future space radioisotope heater units (RHUs) and radioisotope power systems (RPSs)

    NASA Astrophysics Data System (ADS)

    Sholtis, Joseph A.

    2001-02-01

    In early 1999, coated particle fuel was identified as offering promising advancements in design flexibility, performance, specific mass and volume, as well as safety for future space radioisotope heater units (RHUs) and radioisotope power systems (RPSs). Subsequent study, conducted during Fiscal Year 1999, provided confidence that these potential benefits were substantial and demonstrable if a modest follow-on investigative test effort was pursued. This paper lays out a roadmap for both immediate and near-term decision making, as well as any full-scale development and validation of coated particle fuel undertaken for future space RHUs, and RPSs. In an effort to obtain adequate and timely information at a reasonable cost for immediate and near-term decision making, as well as any subsequent development, production, and application decisions, a four-phased regimen of testing is identified. The four phases of testing are: (1) Pre-Decisional Testing: (2) Pre-Production Analytical Verification Testing: (3) Production Quality Assurance Testing: and (4) Post-Production Safety Verification Testing. Although all four of these phases of testing are considered essential, the first two phases are especially important for immediate and near-term decisions to advance and pursue coated particle fuel for space RHUs and RPSs. The third and fourth phases of testing are primarily identified and included for completeness at this early stage. It is concluded that there is every reason to believe that the potential benefits of coated particle fuel can be readily demonstrated through a modest investigative test effort. If such an effort is pursued and proves successful, coated particle fuel could then be developed with assurance that its ultimate benefits would revolutionize the design and space use of future RHUs and RPSs. It is hoped that this paper will serve as a starting point for further discussions and more specific planning activities aimed at advancing coated particle fuel for

  6. Coated powder for electrolyte matrix for carbonate fuel cell

    DOEpatents

    Iacovangelo, Charles D.; Browall, Kenneth W.

    1985-01-01

    A plurality of electrolyte carbonate-coated ceramic particle which does not differ significantly in size from that of the ceramic particle and wherein no significant portion of the ceramic particle is exposed is fabricated into a porous tape comprised of said coated-ceramic particles bonded together by the coating for use in a molten carbonate fuel cell.

  7. Relationship Between Particle and Plasma Properties and Coating Characteristics of Samaria-Doped Ceria Prepared by Atmospheric Plasma Spraying for Use in Solid Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Cuglietta, Mark; Kesler, Olivera

    2012-06-01

    Samaria-doped ceria (SDC) has become a promising material for the fabrication of high-performance, intermediate-temperature solid oxide fuel cells (SOFCs). In this study, the in-flight characteristics, such as particle velocity and surface temperature, of spray-dried SDC agglomerates were measured and correlated to the resulting microstructures of SDC coatings fabricated using atmospheric plasma spraying, a manufacturing technique with the capability of producing full cells in minutes. Plasmas containing argon, nitrogen and hydrogen led to particle surface temperatures higher than those in plasmas containing only argon and nitrogen. A threshold temperature for the successful deposition of SDC on porous stainless steel substrates was calculated to be 2570 °C. Coating porosity was found to be linked to average particle temperature, suggesting that plasma conditions leading to lower particle temperatures may be most suitable for fabricating porous SOFC electrode layers.

  8. Considerations of the Effects of Partial Debonding of the IPyC and Particle Asphericity on TRISCO-coated Fuel Behavior

    SciTech Connect

    G. K. Miller; D. A. Petti; J. T. Maki

    2004-09-01

    The fundamental design for a gas-cooled reactor relies on the behavior of the coated particle fuel. The coating layers surrounding the fuel kernels in these spherical particles, consisting of pyrolytic carbon and silicon carbide layers, act as a pressure vessel that retains fission product gases. Many more fuel particles have failed in US irradiations than would be expected when only one-dimensional pressure vessel failures are considered. Post-irradiation examinations indicate that multi-dimensional effects may have contributed to these failures, such as (1) irradiation-induced shrinkage cracks in the inner pyrocarbon (IPyC) layer, (2) partial debonding between the IPyC and SiC layers, and (3) deviations from a perfectly spherical shape. An approach that was used previously to evaluate the effects of irradiation-induced shrinkage cracks is used herein to assess the effects of partial debonding and asphericity. Results of this investigation serve to identify circumstances where these mechanisms may contribute to particle failures.

  9. Coated particle waste form development

    SciTech Connect

    Oma, K.H.; Buckwalter, C.Q.; Chick, L.A.

    1981-12-01

    Coated particle waste forms have been developed as part of the multibarrier concept at Pacific Northwest Laboratory under the Alternative Waste Forms Program for the Department of Energy. Primary efforts were to coat simulated nuclear waste glass marbles and ceramic pellets with low-temperature pyrolytic carbon (LT-PyC) coatings via the process of chemical vapor deposition (CVD). Fluidized bed (FB) coaters, screw agitated coaters (SAC), and rotating tube coaters were used. Coating temperatures were reduced by using catalysts and plasma activation. In general, the LT-PyC coatings did not provide the expected high leach resistance as previously measured for carbon alone. The coatings were friable and often spalled off the substrate. A totally different concept, thermal spray coating, was investigated at PNL as an alternative to CVD coating. Flame spray, wire gun, and plasma gun systems were evaluated using glass, ceramic, and metallic coating materials. Metal plasma spray coatings (Al, Sn, Zn, Pb) provided a two to three orders-of-magnitude increase in chemical durability. Because the aluminum coatings were porous, the superior leach resistance must be due to either a chemical interaction or to a pH buffer effect. Because they are complex, coated waste form processes rank low in process feasibility. Of all the possible coated particle processes, plasma sprayed marbles have the best rating. Carbon coating of pellets by CVD ranked ninth when compared with ten other processes. The plasma-spray-coated marble process ranked sixth out of eleven processes.

  10. Coated particle waste form development

    NASA Astrophysics Data System (ADS)

    Oma, K. H.; Buckwalter, C. Q.; Chick, L. A.

    1981-12-01

    Coated particle waste forms were developed as part of the multibarrier concept. Primary efforts were to coat simulated nuclear waste glass marbles and ceramic pellets with low temperature pyrolytic carbon (LT-PyC) coatings via the process of chemical vapor deposition (CVD). Fluidized bed coaters, screw agitated coaters, and rotating tube coaters were used. Coating temperatures were reduced by using catalysts and plasma activation. In general, the LT-PyC coatings did not provide the expected high leach resistance as previously measured for carbon alone. The coatings were friable and often spalled off the substrate. A totally different concept, thermal spray coating, was investigated as an alternative to CVD coating. Flame spray, wire gun, and plasma gun systems were evaluated using glass, ceramic, and metallic coating materials. Metal plasma spray coatings (Al, Sn, Zn, Pb) provided a two to three orders of magnitude increase in chemical durability.

  11. Multidimensional multiphysics simulation of TRISO particle fuel

    NASA Astrophysics Data System (ADS)

    Hales, J. D.; Williamson, R. L.; Novascone, S. R.; Perez, D. M.; Spencer, B. W.; Pastore, G.

    2013-11-01

    Multidimensional multiphysics analysis of TRISO-coated particle fuel using the BISON finite element nuclear fuels code is described. The governing equations and material models applicable to particle fuel and implemented in BISON are outlined. Code verification based on a recent IAEA benchmarking exercise is described, and excellent comparisons are reported. Multiple TRISO-coated particles of increasing geometric complexity are considered. The code's ability to use the same algorithms and models to solve problems of varying dimensionality from 1D through 3D is demonstrated. The code provides rapid solutions of 1D spherically symmetric and 2D axially symmetric models, and its scalable parallel processing capability allows for solutions of large, complex 3D models. Additionally, the flexibility to easily include new physical and material models and straightforward ability to couple to lower length scale simulations makes BISON a powerful tool for simulation of coated-particle fuel. Future code development activities and potential applications are identified.

  12. Multidimensional Multiphysics Simulation of TRISO Particle Fuel

    SciTech Connect

    J. D. Hales; R. L. Williamson; S. R. Novascone; D. M. Perez; B. W. Spencer; G. Pastore

    2013-11-01

    Multidimensional multiphysics analysis of TRISO-coated particle fuel using the BISON finite-element based nuclear fuels code is described. The governing equations and material models applicable to particle fuel and implemented in BISON are outlined. Code verification based on a recent IAEA benchmarking exercise is described, and excellant comparisons are reported. Multiple TRISO-coated particles of increasing geometric complexity are considered. It is shown that the code's ability to perform large-scale parallel computations permits application to complex 3D phenomena while very efficient solutions for either 1D spherically symmetric or 2D axisymmetric geometries are straightforward. Additionally, the flexibility to easily include new physical and material models and uncomplicated ability to couple to lower length scale simulations makes BISON a powerful tool for simulation of coated-particle fuel. Future code development activities and potential applications are identified.

  13. Evolution of Particle Bed Reactor Fuel

    NASA Astrophysics Data System (ADS)

    Jensen, Russell R.; Evans, Robert S.; Husser, Dewayne L.; Kerr, John M.

    1994-07-01

    To realize the potential performance advantages inherent in a particle bed reactor (PBR) for nuclear thermal propulsion (NTP) applications, high performance particle fuel is required. This fuel must operate safely and without failure at high temperature in high pressure, flowing hydrogen propellant. The mixed mean outlet temperature of the propellant is an important characteristic of PBR performance. This temperature is also a critical parameter for fuel particle design because it dictates the required maximum fuel operating temperature. In this paper, the evolution in PBR fuel form to achieve higher operating temperatures is discussed and the potential thermal performance of the different fuel types is evaluated. It is shown that the optimum fuel type for operation under the demanding conditions in a PBR is a coated, solid carbide particle.

  14. Evaluation of Alternate Materials for Coated Particle Fuels for the Gas-Cooled Fast Reactor. Laboratory Directed Research and Development Program FY 2006 Final Report

    SciTech Connect

    Paul A. Demkowicz; Karen Wright; Jian Gan; David Petti; Todd Allen; Jake Blanchard

    2006-09-01

    Candidate ceramic materials were studied to determine their suitability as Gas-Cooled Fast Reactor particle fuel coatings. The ceramics examined in this work were: TiC, TiN, ZrC, ZrN, AlN, and SiC. The studies focused on (i) chemical reactivity of the ceramics with fission products palladium and rhodium, (ii) the thermomechanical stresses that develop in the fuel coatings from a variety of causes during burnup, and (iii) the radiation resiliency of the materials. The chemical reactivity of TiC, TiN, ZrC, and ZrN with Pd and Rh were all found to be much lower than that of SiC. A number of important chemical behaviors were observed at the ceramic-metal interfaces, including the formation of specific intermetallic phases and a variation in reaction rates for the different ceramics investigated. Based on the data collected in this work, the nitride ceramics (TiN and ZrN) exhibit chemical behavior that is characterized by lower reaction rates with Pd and Rh than the carbides TiC and ZrC. The thermomechanical stresses in spherical fuel particle ceramic coatings were modeled using finite element analysis, and included contributions from differential thermal expansion, fission gas pressure, fuel kernel swelling, and thermal creep. In general the tangential stresses in the coatings during full reactor operation are tensile, with ZrC showing the lowest values among TiC, ZrC, and SiC (TiN and ZrN were excluded from the comprehensive calculations due to a lack of available materials data). The work has highlighted the fact that thermal creep plays a critical role in the development of the stress state of the coatings by relaxing many of the stresses at high temperatures. To perform ion irradiations of sample materials, an irradiation beamline and high-temperature sample irradiation stage was constructed at the University of Wisconsin’s 1.7MV Tandem Accelerator Facility. This facility is now capable of irradiating of materials to high dose while controlling sample temperature

  15. The development of CVR coatings for PBR fuels

    NASA Astrophysics Data System (ADS)

    Barletta, R. E.; Vanier, P. E.; Dowell, M. B.; Lennartz, J. A.

    Particle bed reactors (PBR's) are being developed for both space power and propulsion applications. These reactors operate with exhaust gas temperatures of 2500 to 3000 K and fuel temperatures hundreds of degrees higher. One fuel design for these reactors consists of uranium carbide encapsulated in either carbon or graphite. This fuel kernel must be protected from the coolant gas, usually H2, both to prevent attack of the kernel and to limit fission product release. Refractory carbide coatings have been proposed for this purpose. The typical coating process used for this is a chemical vapor deposition. Testing of other components have indicated the superiority of refractory carbide coatings applied using a chemical vapor reaction (CVR) process, however technology to apply these coatings to large numbers of fuel particles with diameters on the order of 500 pm were not readily available. A process to deposit these CVR coatings on surrogate fuel consisting of graphite particles is described. Several types of coatings have been applied to the graphite substrate: NbC in various thicknesses and a bilayer coating consisting of NbC and TaC with a intermediate layer of pyrolytic graphite. These coated particles have been characterized prior to test; results are presented.

  16. Particle adhesion in powder coating

    SciTech Connect

    Mazumder, M.K.; Wankum, D.L.; Knutson, M.; Williams, S.; Banerjee, S.

    1996-12-31

    Electrostatic powder coating is a widely used industrial painting process. It has three major advantages: (1) it provides high quality durable finish, (2) the process is environmentally friendly and does not require the use of organic solvents, and (3) it is economically competitive. The adhesion of electrostatically deposited polymer paint particles on the grounded conducting substrate depends upon many parameters: (a) particle size and shape distributions, (b) electrostatic charge distributions, (c) electrical resistivity, (d) dielectric strength of the particles, (e) thickness of the powder film, (f) presence and severity of the back corona, and (g) the conductivity and surface properties of the substrate. The authors present a model on the forces of deposition and adhesion of corona charged particles on conducting substrates.

  17. Method of identifying defective particle coatings

    DOEpatents

    Cohen, Mark E.; Whiting, Carlton D.

    1986-01-01

    A method for identifying coated particles having defective coatings desig to retain therewithin a build-up of gaseous materials including: (a) Pulling a vacuum on the particles; (b) Backfilling the particles at atmospheric pressure with a liquid capable of wetting the exterior surface of the coated particles, said liquid being a compound which includes an element having an atomic number higher than the highest atomic number of any element in the composition which forms the exterior surface of the particle coating; (c) Drying the particles; and (d) Radiographing the particles. By television monitoring, examination of the radiographs is substantially enhanced.

  18. Preparation, Characterization and Performance of CVR Coatings for PBR Fuels

    NASA Astrophysics Data System (ADS)

    Adams, J. W.; Barletta, R. E.; Vanier, P. E.; Dowell, M. B.; Lennartz, J. W.

    1994-07-01

    As a part of the US Space Nuclear Thermal Propulsion Program, a process to deposit refractory carbide coatings using a fluidized bed chemical vapor reaction (CVR) process has been developed. Several types of coating have been applied to the graphite substrate which served as a surrogate fuel kernel. The coatings include NbC in various thicknesses and a bilayer coating consisting of NbC and TaC with an intermediate layer of pyrolytic graphite(PG). They were applied to a surrogate fuel kernel consisting of a PG-coated, graphite particle. The particles were characterized prior to test for coating thickness, grain size, stoichiometry (NbC only), free carbon and surface area. The initial screening tests for these coatings consisted of heating in flowing hot hydrogen at one atmosphere. The carbon loss from these particles was measured as a function of time. Exposure temperatures ranging from 2500 to 3000 K were used and samples were exposed for up to 14 minutes in a cyclical fashion, cooling to room temperature between exposures. Microscopic examination of the coatings after exposure was conducted. The rate of weight loss from these particles can be characterized as a simple Arrhenius process. These rates are compared to that from other tests of coated materials under similar conditions.

  19. Nuclear fuel particles and method of making nuclear fuel compacts therefrom

    DOEpatents

    DeVelasco, Rubin I.; Adams, Charles C.

    1991-01-01

    Methods for making nuclear fuel compacts exhibiting low heavy metal contamination and fewer defective coatings following compact fabrication from a mixture of hardenable binder, such as petroleum pitch, and nuclear fuel particles having multiple layer fission-product-retentive coatings, with the dense outermost layer of the fission-product-retentive coating being surrounded by a protective overcoating, e.g., pyrocarbon having a density between about 1 and 1.3 g/cm.sup.3. Such particles can be pre-compacted in molds under relatively high pressures and then combined with a fluid binder which is ultimately carbonized to produce carbonaceous nuclear fuel compacts having relatively high fuel loadings.

  20. Fracture strength and principal stress fields during crush testing of the SiC layer in TRISO-coated fuel particles

    NASA Astrophysics Data System (ADS)

    Davis, Brian C.; Ward, Logan; Butt, Darryl P.; Fillery, Brent; Reimanis, Ivar

    2016-08-01

    Diametrical compression testing is an important technique to evaluate fracture properties of the SiC layer in TRISO-coated nuclear fuel particles. This study was conducted to expand the understanding and improve the methodology of the test. An analytic solution and multiple FEA models are used to determine the development of the principal stress fields in the SiC shell during a crush test. An ideal fracture condition where the diametrical compression test best mimics in-service internal pressurization conditions was discovered. For a small set of empirical data points, results from different analysis methodologies were input to an iterative Weibull equation set to determine characteristic strength (332.9 MPa) and Weibull modulus (3.80). These results correlate well with published research. It is shown that SiC shell asphericity is currently the limiting factor of greatest concern to obtaining repeatable results. Improvements to the FEA are the only apparent method for incorporating asphericity and improving accuracy.

  1. Coating parameters of zirconium carbide on advanced TRISO fuels

    NASA Astrophysics Data System (ADS)

    Dulude, Michael C.

    The feasibility of using very high temperature reactors (VHTR) as part of the next generation of nuclear reactors greatly depends on the tri-structural isotropic (TRISO) fuel particles reliability to retain both gaseous and metallic fission products created in irradiated UO2. Most research devoted to TRISO fuel particles has focused on the characteristics and retention ability of silicon carbide as the main barrier against metallic fission products. This work investigates the deposition parameters necessary to create advanced TRISO particles consisting of the standard SiC TRISO coatings with an additional layer of ZrC applied directly to the UO2 fuel kernel. The additional ZrC layer will act as an oxygen getter to prevent failure mechanisms experienced in TRISO particles. Two failure mechanisms that are of the most concern are the over pressurization of the particles and kernel migration within the TRISO particles. In this study successful ZrC coatings were created and the deposition characteristics were analyzed via optical and SEM microscopy techniques. The ZrC layer was confirmed through XRD analysis. This investigation also reduced U3O8 microspheres to UO2 in an argon atmosphere. The oxygen to metal ratio from the reduced U3O8 was back calculated from oxidation analysis performed with a TGA machine. Once consistent repeatability is shown with coating surrogate zirconia kernels, advanced TRISO coatings will be deposited on the UO2 fuel kernels.

  2. Method for fluidizing and coating ultrafine particles, device for fluidizing and coating ultrafine particles

    SciTech Connect

    Li, Jie; Liu, Yung Y

    2015-01-20

    The invention provides a method for dispersing particles within a reaction field, the method comprising confining the particles to the reaction field using a standing wave. The invention also provides a system for coating particles, the system comprising a reaction zone; a means for producing fluidized particles within the reaction zone; a fluid to produce a standing wave within the reaction zone; and a means for introducing coating moieties to the reaction zone. The invention also provides a method for coating particles, the method comprising fluidizing the particles, subjecting the particles to a standing wave; and contacting the subjected particles with a coating moiety.

  3. Coated U(Mo) Fuel: As-Fabricated Microstructures

    SciTech Connect

    Emmanuel Perez; Dennis D. Keiser, Jr.; Ann Leenaers; Sven Van den Berghe; Tom Wiencek

    2014-04-01

    As part of the development of low-enriched uranium fuels, fuel plates have recently been tested in the BR-2 reactor as part of the SELENIUM experiment. These fuel plates contained fuel particles with either Si or ZrN thin film coating (up to 1 µm thickness) around the U-7Mo fuel particles. In order to best understand irradiation performance, it is important to determine the starting microstructure that can be observed in as-fabricated fuel plates. To this end, detailed microstructural characterization was performed on ZrN and Si-coated U-7Mo powder in samples taken from AA6061-clad fuel plates fabricated at 500°C. Of interest was the condition of the thin film coatings after fabrication at a relatively high temperature. Both scanning electron microscopy and transmission electron microscopy were employed. The ZrN thin film coating was observed to consist of columns comprised of very fine ZrN grains. Relatively large amounts of porosity could be found in some areas of the thin film, along with an enrichment of oxygen around each of the the ZrN columns. In the case of the pure Si thin film coating sample, a (U,Mo,Al,Si) interaction layer was observed around the U-7Mo particles. Apparently, the Si reacted with the U-7Mo and Al matrix during fuel plate fabrication at 500°C to form this layer. The microstructure of the formed layer is very similar to those that form in U-7Mo versus Al-Si alloy diffusion couples annealed at higher temperatures and as-fabricated U-7Mo dispersion fuel plates with Al-Si alloy matrix fabricated at 500°C.

  4. Advanced Fuels Campaign Cladding & Coatings Meeting Summary

    SciTech Connect

    Not Listed

    2013-03-01

    The Fuel Cycle Research and Development (FCRD) Advanced Fuels Campaign (AFC) organized a Cladding and Coatings operational meeting February 12-13, 2013, at Oak Ridge National Laboratory (ORNL). Representatives from the U.S. Department of Energy (DOE), national laboratories, industry, and universities attended the two-day meeting. The purpose of the meeting was to discuss advanced cladding and cladding coating research and development (R&D); review experimental testing capabilities for assessing accident tolerant fuels; and review industry/university plans and experience in light water reactor (LWR) cladding and coating R&D.

  5. Hollow sphere ceramic particles for abradable coatings

    SciTech Connect

    Longo, F.N.; Bader, N.F. III; Dorfman, M.R.

    1984-05-22

    A hollow sphere ceramic flame spray powder is disclosed. The desired constituents are first formed into agglomerated particles in a spray drier. Then the agglomerated particles are introduced into a plasma flame which is adjusted so that the particles collected are substantially hollow. The hollow sphere ceramic particles are suitable for flame spraying a porous and abradable coating. The hollow particles may be selected from the group consisting of zirconium oxide and magnesium zirconate.

  6. Dense silica coatings on ceramic powder particles

    SciTech Connect

    Opitz, J.F.A.; Mayr, W.

    1995-09-01

    Dense silica coatings on the surface of inorganic powders particles are prepared by the hydrolysis of tetraethoxysilane (TEOS) in alcoholic suspensions. In a first reaction step, the TEOS is pre-hydrolysed in acidic solution and afterwards, a suspension of powder particles in this reaction solution is treated with ammonia which results in a dense silica coating of typically 10 - 100 nm thickness. Different luminescent powders which are used in the manufacture of cathode-ray tubes or fluorescent lamps have been coated by this procedure. The silica coating forms a transparent layer and the suspension properties of the coated powders are determined by the silica layer. The silica coating also protects sulfidic luminescent powders from being attacked by oxidizing agents like dichromate ions which are used in the suspension formulations for TV tube fabrication.

  7. Article coated with flash bonded superhydrophobic particles

    DOEpatents

    Simpson, John T [Clinton, TN; Blue, Craig A [Knoxville, TN; Kiggans, Jr., James O [Oak Ridge, TN

    2010-07-13

    A method of making article having a superhydrophobic surface includes: providing a solid body defining at least one surface; applying to the surface a plurality of diatomaceous earth particles and/or particles characterized by particle sizes ranging from at least 100 nm to about 10 .mu.m, the particles being further characterized by a plurality of nanopores, wherein at least some of the nanopores provide flow through porosity, the particles being further characterized by a plurality of spaced apart nanostructured features that include a contiguous, protrusive material; flash bonding the particles to the surface so that the particles are adherently bonded to the surface; and applying a hydrophobic coating layer to the surface and the particles so that the hydrophobic coating layer conforms to the nanostructured features.

  8. Pyrolytic carbon-coated nuclear fuel

    DOEpatents

    Lindemer, Terrence B.; Long, Jr., Ernest L.; Beatty, Ronald L.

    1978-01-01

    An improved nuclear fuel kernel having at least one pyrolytic carbon coating and a silicon carbon layer is provided in which extensive interaction of fission product lanthanides with the silicon carbon layer is avoided by providing sufficient UO.sub.2 to maintain the lanthanides as oxides during in-reactor use of said fuel.

  9. Treating asphericity in fuel particle pressure vessel modeling

    NASA Astrophysics Data System (ADS)

    Miller, Gregory K.; Wadsworth, Derek C.

    1994-07-01

    The prototypical nuclear fuel of the New Production Modular High Temperature Gas-Cooled Reactor (NP-MHTGR) consists of spherical TRISO-coated particles suspended in graphite cylinders. The coating layers surrounding the fuel kernels in these particles consist of pyrolytic carbon layers and a silicon carbide layer. These coating layers act as a pressure vessel which retains fission product gases. In the operating conditions of the NP-MHTGR, a small percentage of these particles (pressure vessels) are expected to fail due to the pressure loading. The fuel particles of the NP-MHTGR deviate to some degree from a true spherical shape, which may have some effect on the failure percentages. A method is presented that treats the asphericity of the particles in predicting failure probabilities for particle samples. It utilizes a combination of finite element analysis and Monte Carlo sampling and is based on the Weibull statistical theory. The method is used here to assess the effects of asphericity in particles of two common geometric shapes, i.e. faceted particles and ellipsoidal particles. The method presented could be used to treat particle anomalies other than asphericity.

  10. The measurement of silver diffusivity in zirconium carbide to study the release behavior of 110mAg in the ZrC TRISO-coated nuclear fuel particle

    NASA Astrophysics Data System (ADS)

    Yang, Young-Ki; Allen, Todd R.

    2016-03-01

    The tri-structural isotropic (TRISO) coated particle fuel has been developed and used for high temperature gas-cooled reactors (HTGRs). It provides a unique robustness of the first barrier for the fission products. The TRISO fuel particle has typically consisted of a UO2 or UCO kernel, surrounded by successive layers of porous carbon, dense inner pyrocarbon, silicon carbide, and dense outer pyrocarbon. During operation, however, the SiC layer has been known to release radioactive silver 110mAg which makes maintenance more difficult and thus costly. Zirconium carbide has been considered as a promising alternative to the SiC fission product barrier. ZrC exhibits high temperature stability and possibly possesses superior Pd resistance, while the retention properties especially for silver have not been adequately studied. To help elucidate the diffusive behavior of silver in the ZrC coating of the TRISO-coated particle, a new diffusion experimental technique, called the encapsulating source method, has been developed by constructing a constant source diffusion couple between ZrC and Ag gas originated from Zr-Ag solid solution. Scanning electron microscopy (SEM), wavelength-dispersive X-ray spectroscopy (WDS), electron backscatter diffraction (EBSD) and optical methods were used to analyze the diffusion couple annealed at 1500 °C. The resultant diffusion coefficient of Ag in single-crystalline ZrC0.84 at 1500 °C was experimentally determined to be about 2.8 (±1.2) × 10-17 m2/s.

  11. Behavior of magnetorheological elastomers with coated particles

    NASA Astrophysics Data System (ADS)

    Behrooz, Majid; Sutrisno, Joko; Zhang, Lingyue; Fuchs, Alan; Gordaninejad, Faramarz

    2015-03-01

    Iron particle coating can improve the behavior of magnetorheological elastomers (MREs) by inhibiting iron particle rusting; however, such a process can change physical properties of MREs such as oxidation resistance, shear modulus, and stiffness change due to an applied magnetic field. In this study, MRE samples are fabricated with regular and polymerized iron particles. To investigate the possibility and extent of these changes, polymerized particle MRE samples are made using a combination of reversible addition fragmentation chain transfer and click chemistry. Shear test sample MREs with pure elastomer and 50 wt% MRE with and without polymerization are fabricated. To observe the effect of oxidation on shear properties of MREs, pure elastomer and 50 wt% coated and non-coated samples are oxidized using accelerated oxidation procedure. Experimental results show that oxidation significantly reduces the shear modulus of the elastomer matrix. The coating process of iron particles does not significantly change the shear modulus of resulting MREs but reduces the loss of shear modulus due to oxidation.

  12. Mapping organic coatings on atmospheric particles

    NASA Astrophysics Data System (ADS)

    Russell, Lynn M.; Maria, Steven F.; Myneni, Satish C. B.

    2002-08-01

    To date there is no direct evidence of the distribution or characteristics of organic compounds in individual particles because techniques for chemically identifying organic compounds are not sufficiently sensitive to detect molecules or functional groups with masses below 10-15 g [Husar and Shu, 1975]. Here we present detailed maps of organic groups (aromatic, alkyl, ketonic carbonyl and carboxylic carbonyl groups) and inorganic ions (potassium, carbonate, calcium) in individual dry particles with diameters ranging from 0.2 to 10 μm using a new technique for aerosol characterization by soft X-ray spectromicroscopy at atmospheric pressure. The maps show both the compounds present in individual particles and regions of different compositions within particles. The particle compositions on surfaces are enhanced in shorter chain or more oxygenated groups, providing the first observations of surface active carboxylic acids in organic coatings in atmospheric particles.

  13. Composite of coated magnetic alloy particle

    DOEpatents

    Moorhead, Arthur J.; Kim, Hyoun-Ee

    2000-01-01

    A composite structure and method for manufacturing same, the composite structure being comprised of metal particles and an inorganic bonding media. The method comprises the steps of coating particles of a metal powder with a thin layer of an inorganic bonding media selected from the group of powders consisting of a ceramic, glass, and glass-ceramic. The particles are assembled in a cavity and heat, with or without the addition of pressure, is thereafter applied to the particles until the layer of inorganic bonding media forms a strong bond with the particles and with the layer of inorganic bonding media on adjacent particles. The resulting composite structure is strong and remains cohesive at high temperatures.

  14. Ion sequestration particles for naval anticorrosion coatings

    NASA Astrophysics Data System (ADS)

    Zguris, Zachary Z.

    Corrosion is the electrochemical process of a metal returning to its lower energy state, the metal oxide. The cost of corrosion is difficult to estimate. One area particularly susceptible to corrosion problems with high maintenance costs is that of the 20,000 tanks existent in the US Naval Fleet. The Navy is sponsoring the development of novel coatings and additives that can be used to decrease the rising corrosion related costs. This dissertation describes in detail the synthesis of Ion Sequestration Particles (ISP) that when added to the standard MIL-DTL-24441 or potentially another coating system act to enhance the anticorrosion properties of the coating. A solid ion sequestration core material (SISCM) is first produced. The core is then encapsulated in a second stage forming a shell that protects the SISCM sufficiently from the harmful interactions with uncured epoxy based coatings. ISPs were designed to sequester harmful ions while releasing passivating ions in their place. The passivating ions then migrate to defect sites at the coating interface where they act to inhibit corrosion. The anticorrosion performance of ISPs in epoxy coatings has been demonstrated by both 500 hrs of hot deionized water immersion and 1000 hrs of salt spray exposure (ASTM B117). The best improvements in coating performance are attained with ISP content ranging from 5-10 wt % loading in a coating. ISPs were designed to limit the transport of harmful ions through the coating. However this work has determined high diffusion coefficients for ions (CI- and PO42-) through the epoxy matrix. Without ISPs, the diffusion coefficient through the MIL-DTL-24441 coating was determined for phosphate to be 1.16x10-7 cm2/s and for chloride to be in the range of 2.7x10-9 to 5.6x10-10 cm2/s. The addition of 5 wt % ISPs to the coating had the effect of decreasing the diffusion coefficient by an average of 25.5%. These results yield the conclusion that the enhanced anticorrosion properties of coatings

  15. Method for applying pyrolytic carbon coatings to small particles

    DOEpatents

    Beatty, Ronald L.; Kiplinger, Dale V.; Chilcoat, Bill R.

    1977-01-01

    A method for coating small diameter, low density particles with pyrolytic carbon is provided by fluidizing a bed of particles wherein at least 50 per cent of the particles have a density and diameter of at least two times the remainder of the particles and thereafter recovering the small diameter and coated particles.

  16. Carbon fuel particles used in direct carbon conversion fuel cells

    SciTech Connect

    Cooper, John F.; Cherepy, Nerine

    2012-10-09

    A system for preparing particulate carbon fuel and using the particulate carbon fuel in a fuel cell. Carbon particles are finely divided. The finely dividing carbon particles are introduced into the fuel cell. A gas containing oxygen is introduced into the fuel cell. The finely divided carbon particles are exposed to carbonate salts, or to molten NaOH or KOH or LiOH or mixtures of NaOH or KOH or LiOH, or to mixed hydroxides, or to alkali and alkaline earth nitrates.

  17. Carbon fuel particles used in direct carbon conversion fuel cells

    DOEpatents

    Cooper, John F.; Cherepy, Nerine

    2011-08-16

    A system for preparing particulate carbon fuel and using the particulate carbon fuel in a fuel cell. Carbon particles are finely divided. The finely dividing carbon particles are introduced into the fuel cell. A gas containing oxygen is introduced into the fuel cell. The finely divided carbon particles are exposed to carbonate salts, or to molten NaOH or KOH or LiOH or mixtures of NaOH or KOH or LiOH, or to mixed hydroxides, or to alkali and alkaline earth nitrates.

  18. Carbon fuel particles used in direct carbon conversion fuel cells

    DOEpatents

    Cooper, John F.; Cherepy, Nerine

    2012-01-24

    A system for preparing particulate carbon fuel and using the particulate carbon fuel in a fuel cell. Carbon particles are finely divided. The finely dividing carbon particles are introduced into the fuel cell. A gas containing oxygen is introduced into the fuel cell. The finely divided carbon particles are exposed to carbonate salts, or to molten NaOH or KOH or LiOH or mixtures of NaOH or KOH or LiOH, or to mixed hydroxides, or to alkali and alkaline earth nitrates.

  19. Carbon Fuel Particles Used in Direct Carbon Conversion Fuel Cells

    DOEpatents

    Cooper, John F.; Cherepy, Nerine

    2008-10-21

    A system for preparing particulate carbon fuel and using the particulate carbon fuel in a fuel cell. Carbon particles are finely divided. The finely dividing carbon particles are introduced into the fuel cell. A gas containing oxygen is introduced into the fuel cell. The finely divided carbon particles are exposed to carbonate salts, or to molten NaOH or KOH or LiOH or mixtures of NaOH or KOH or LiOH, or to mixed hydroxides, or to alkali and alkaline earth nitrates.

  20. Assessment of ceramic coatings for metal fuel melting crucible

    SciTech Connect

    Kim, Ki-Hwan; Song, Hoon; Kim, Jong-Hwan; Oh, Seok-Jin; Kim, Hyung-Tae; Lee, Chan-Bock

    2013-07-01

    The objective of this study is to develop a coating method and material for crucibles to prevent material interactions with the U-Zr/U-TRU-Zr fuels during the manufacturing of SFR fuels. Refractory coatings were applied to niobium substrates by vacuum plasma-spray coating method. Melt dipping tests conducted were the coated rods lowered into the fuel melt at 1600 C. degrees, and withdrawn and cooled outside the crucible in the inert atmosphere of the induction furnace. Melt dipping tests of the coated Nb rods indicated that plasma-sprayed Y{sub 2}O{sub 3} coating doesn't form significant reaction layer between fuel melt and coating layer. Melt dipping tests of the coated Nb rods showed that TiC, TaC, and Y{sub 2}O{sub 3} coatings exhibited the promising performance among other ceramic coatings. These materials could be promising candidate materials for the reusable melt crucible of metal fuel for SFR. In addition, in order to develop the vacuum plasma-spray coating method for re-usable crucible of metal fuel slugs to be overcome the issue of thermal expansion mismatch between coating material and crucible, various combinations of coating conditions were investigated to find the bonding effect on the substrate in pursuit of more effective ways to withstand the thermal stresses. It is observed that most coating methods maintained sound coating state in U-Zr melt. (authors)

  1. Molecular Level Coating for Metal Oxide Particles

    NASA Technical Reports Server (NTRS)

    McDaniel, Patricia R. (Inventor); Saint Clair, Terry L. (Inventor)

    2000-01-01

    Polymer encapsulated metal oxide particles are prepared by combining a polyamide acid in a polar aprotic solvent with a metal alkoxide solution. The polymer was imidized and the metal oxide formed simultaneously in a refluxing organic solvent. The resulting polymer-metal oxide is an intimately mixed commingled blend, possessing synergistic properties of both the polymer and preceramic metal oxide. The encapsulated metal oxide particles have multiple uses including, being useful in the production of skin lubricating creams, weather resistant paints, as a filler for paper, making ultraviolet light stable filled printing ink, being extruded into fibers or ribbons, and coatings for fibers used in the production of composite structural panels.

  2. Design of an Online Fission Gas Monitoring System for Post-irradiation Examination Heating Tests of Coated Fuel Particles for High-Temperature Gas-Cooled Reactors

    SciTech Connect

    Dawn Scates

    2010-10-01

    A new Fission Gas Monitoring System (FGMS) has been designed at the Idaho National Laboratory (INL) for use of monitoring online fission gas-released during fuel heating tests. The FGMS will be used with the Fuel Accident Condition Simulator (FACS) at the Hot Fuels Examination Facility (HFEF) located at the Materials and Fuels Complex (MFC) within the INL campus. Preselected Advanced Gas Reactor (AGR) TRISO (Tri-isotropic) fuel compacts will undergo testing to assess the fission product retention characteristics under high temperature accident conditions. The FACS furnace will heat the fuel to temperatures up to 2,000ºC in a helium atmosphere. Released fission products such as Kr and Xe isotopes will be transported downstream to the FGMS where they will accumulate in cryogenically cooledcollection traps and monitored with High Purity Germanium (HPGe) detectors during the heating process. Special INL developed software will be used to monitor the accumulated fission products and will report data in near real-time. These data will then be reported in a form that can be readily available to the INL reporting database. This paper describes the details of the FGMS design, the control and acqusition software, system calibration, and the expected performance of the FGMS. Preliminary online data may be available for presentation at the High Temperature Reactor (HTR) conference.

  3. Platinum- and platinum alloy-coated palladium and palladium alloy particles and uses thereof

    DOEpatents

    Adzic, Radoslav; Zhang, Junliang; Mo, Yibo; Vukmirovic, Miomir Branko

    2010-04-06

    The present invention relates to particle and nanoparticle composites useful as oxygen-reduction electrocatalysts. The particle composites are composed of a palladium or palladium-alloy particle or nanoparticle substrate coated with an atomic submonolayer, monolayer, bilayer, or trilayer of zerovalent platinum atoms. The invention also relates to a catalyst and a fuel cell containing the particle or nanoparticle composites of the invention. The invention additionally includes methods for oxygen reduction and production of electrical energy by using the particle and nanoparticle composites of the invention.

  4. Observation of nitrate coatings on atmospheric mineral dust particles

    NASA Astrophysics Data System (ADS)

    Li, W. J.; Shao, L. Y.

    2009-03-01

    Nitrate compounds have received much attention because of their ability to alter the hygroscopic properties and cloud condensation nuclei (CCN) activity of mineral dust particles in the atmosphere. However, very little is known about specific characteristics of ambient nitrate-coated mineral particles on an individual particle scale. In this study, sample collection was conducted during brown haze and dust episodes between 24 May and 21 June 2007 in Beijing, northern China. Sizes, morphologies, and compositions of 332 mineral dust particles together with their coatings were analyzed using transmission electron microscopy (TEM) coupled with energy-dispersive X-ray (EDX) microanalyses. Structures of some mineral particles were verified using selected-area electron diffraction (SAED). TEM observation indicates that approximately 90% of the collected mineral particles are covered by visible coatings in haze samples whereas only 5% are coated in the dust sample. 92% of the analyzed mineral particles are covered with Ca-, Mg-, and Na-rich coatings, and 8% are associated with K- and S-rich coatings. The majority of coatings contain Ca, Mg, O, and N with minor amounts of S and Cl, suggesting that they are possibly nitrates mixed with small amounts of sulfates and chlorides. These nitrate coatings are strongly correlated with the presence of alkaline mineral components (e.g., calcite and dolomite). CaSO4 particles with diameters from 10 to 500 nm were also detected in the coatings including Ca(NO3)2 and Mg(NO3)2. Our results indicate that mineral particles in brown haze episodes were involved in atmospheric heterogeneous reactions with two or more acidic gases (e.g., SO2, NO2, HCl, and HNO3). Mineral particles that acquire hygroscopic nitrate coatings tend to be more spherical and larger, enhancing their light scattering and CCN activity, both of which have cooling effects on the climate.

  5. Superoleophilic particles and coatings and methods of making the same

    SciTech Connect

    Simpson, John T; D'Urso, Brian

    2013-07-30

    Superoleophilic particles and surfaces and methods of making the same are described. The superoleophilic particles can include porous particles having a hydrophobic coating layer deposited thereon. The coated porous particles are characterized by particle sizes ranging from at least 100 nm to about 10 .mu.m and a plurality of nanopores. Some of the nanopores provide flow through porosity. The superoleophilic particles also include oil pinned within the nanopores of the porous particles The plurality of porous particles can include (i) particles including a plurality of spaced apart nanostructured features comprising a contiguous, protrusive material, (ii) diatomaceous earth particles, or (iii) both. The surfaces can include the superoleophilic particles coupled to the surface.

  6. Helium release from 238PuO2 fuel particles

    NASA Astrophysics Data System (ADS)

    El-Genk, Mohamed S.; Tournier, Jean-Michel

    2000-01-01

    Coated plutonia fuel particles have recently been proposed for potential use in future space exploration missions that employ radioisotope power systems and/or radioisotope heater units (RHUs). The design of this fuel form calls for full retention of the helium generated by the natural radioactive decay of 238Pu, with the aid of a strong zirconium carbide coating. This paper reviews the potential release mechanisms of helium in small-grain (7-40 μm) plutonia pellets currently being used in the General Purpose Heat Source (GPHS) modules and RHUs, during both steady-state and transient heating conditions. The applicability of these mechanisms to large-grain and polycrystalline 238PuO2 fuel kernels is examined and estimates of helium release during a re-entry heating pulse up to 1723 K are presented. These estimates are based on the reported data for fission gas release from granular and monocrystal UO2 fuel particles irradiated at isothermal conditions up to 6.4 at.% burnup and 2030 K. It is concluded that the helium release fraction from large-grain (>=300 μm) plutonia fuel kernels heated up to 1723 K could be less than 7%, compared to ~80% from small-grain (7-40 μm) fuel. The helium release fraction from polycrystalline plutonia kernels fabricated using Sol-Gel techniques could be even lower. Sol-Gel fabrication processes are favored over powder metallurgy, because of their high precision and excellent reproducibility and the absence of a radioactive dust waste stream, significantly reducing the fabrication and post-fabrication clean-up costs. .

  7. Evaluating of scale-up methodologies of gas-solid spouted beds for coating TRISO nuclear fuel particles using advanced measurement techniques

    NASA Astrophysics Data System (ADS)

    Ali, Neven Y.

    The work focuses on implementing for the first time advanced non-invasive measurement techniques to evaluate the scale-up methodology of gas-solid spouted beds for hydrodynamics similarity that has been reported in the literature based on matching dimensionless groups and the new mechanistic scale up methodology that has been developed in our laboratory based on matching the radial profile of gas holdup since the gas dynamics dictate the hydrodynamics of the gas-solid spouted beds. These techniques are gamma-ray computed tomography (CT) to measure the cross-sectional distribution of the phases' holdups and their radial profiles along the bed height and radioactive particle tracking (RPT) to measure in three-dimension (3D) solids velocity and their turbulent parameters. The measured local parameters and the analysis of the results obtained in this work validate our new methodology of scale up of gas-solid spouted beds by comparing for the similarity the phases' holdups and the dimensionless solids velocities and their turbulent parameters that are non-dimensionalized using the minimum spouting superficial gas velocity. However, the scale-up methodology of gas-solid spouted beds that is based on matching dimensionless groups has not been validated for hydrodynamics similarity with respect to the local parameters such as phases' holdups and dimensionless solids velocities and their turbulent parameters. Unfortunately, this method was validated in the literature by only measuring the global parameters. Thus, this work confirms that validation of the scale-up methods of gas-solid spouted beds for hydrodynamics similarity should reside on measuring and analyzing the local hydrodynamics parameters.

  8. Microfluidic conformal coating of non-spherical magnetic particles.

    PubMed

    Moon, Byeong-Ui; Hakimi, Navid; Hwang, Dae Kun; Tsai, Scott S H

    2014-09-01

    We present the conformal coating of non-spherical magnetic particles in a co-laminar flow microfluidic system. Whereas in the previous reports spherical particles had been coated with thin films that formed spheres around the particles; in this article, we show the coating of non-spherical particles with coating layers that are approximately uniform in thickness. The novelty of our work is that while liquid-liquid interfacial tension tends to minimize the surface area of interfaces-for example, to form spherical droplets that encapsulate spherical particles-in our experiments, the thin film that coats non-spherical particles has a non-minimal interfacial area. We first make bullet-shaped magnetic microparticles using a stop-flow lithography method that was previously demonstrated. We then suspend the bullet-shaped microparticles in an aqueous solution and flow the particle suspension with a co-flow of a non-aqueous mixture. A magnetic field gradient from a permanent magnet pulls the microparticles in the transverse direction to the fluid flow, until the particles reach the interface between the immiscible fluids. We observe that upon crossing the oil-water interface, the microparticles become coated by a thin film of the aqueous fluid. When we increase the two-fluid interfacial tension by reducing surfactant concentration, we observe that the particles become trapped at the interface, and we use this observation to extract an approximate magnetic susceptibility of the manufactured non-spherical microparticles. Finally, using fluorescence imaging, we confirm the uniformity of the thin film coating along the entire curved surface of the bullet-shaped particles. To the best of our knowledge, this is the first demonstration of conformal coating of non-spherical particles using microfluidics. PMID:25332731

  9. Aqueous alteration of VHTR fuels particles under simulated geological conditions

    NASA Astrophysics Data System (ADS)

    Ait Chaou, Abdelouahed; Abdelouas, Abdesselam; Karakurt, Gökhan; Grambow, Bernd

    2014-05-01

    Very High Temperature Reactor (VHTR) fuels consist of the bistructural-isotropic (BISO) or tristructural-isotropic (TRISO)-coated particles embedded in a graphite matrix. Management of the spent fuel generated during VHTR operation would most likely be through deep geological disposal. In this framework we investigated the alteration of BISO (with pyrolytic carbon) and TRISO (with SiC) particles under geological conditions simulated by temperatures of 50 and 90 °C and in the presence of synthetic groundwater. Solid state (scanning electron microscopy (SEM), micro-Raman spectroscopy, electron probe microanalyses (EPMA) and X-ray photoelectron spectroscopy (XPS)) and solution analyses (ICP-MS, ionique chromatography (IC)) showed oxidation of both pyrolytic carbon and SiC at 90 °C. Under air this led to the formation of SiO2 and a clay-like Mg-silicate, while under reducing conditions (H2/N2 atmosphere) SiC and pyrolytic carbon were highly stable after a few months of alteration. At 50 °C, in the presence and absence of air, the alteration of the coatings was minor. In conclusion, due to their high stability in reducing conditions, HTR fuel disposal in reducing deep geological environments may constitute a viable solution for their long-term management.

  10. Cold spray deposition of Ti2AlC coatings for improved nuclear fuel cladding

    NASA Astrophysics Data System (ADS)

    Maier, Benjamin R.; Garcia-Diaz, Brenda L.; Hauch, Benjamin; Olson, Luke C.; Sindelar, Robert L.; Sridharan, Kumar

    2015-11-01

    Coatings of Ti2AlC MAX phase compound have been successfully deposited on Zircaloy-4 (Zry-4) test flats, with the goal of enhancing the accident tolerance of LWR fuel cladding. Low temperature powder spray process, also known as cold spray, has been used to deposit coatings ∼90 μm in thickness using powder particles of <20 μm. X-ray diffraction analysis showed the phase-content of the deposited coatings to be identical to the powders indicating that no phase transformation or oxidation had occurred during the coating deposition process. The coating exhibited a high hardness of about 800 HK and pin-on-disk wear tests using abrasive ruby ball counter-surface showed the wear resistance of the coating to be significantly superior to the Zry-4 substrate. Scratch tests revealed the coatings to be well-adhered to the Zry-4 substrate. Such mechanical integrity is required for claddings from the standpoint of fretting wear resistance and resisting wear handling and insertion. Air oxidation tests at 700 °C and simulated LOCA tests at 1005 °C in steam environment showed the coatings to be significantly more oxidation resistant compared to Zry-4 suggesting that such coatings can potentially provide accident tolerance to nuclear fuel cladding.

  11. Microfluidic conformal coating of non-spherical magnetic particles

    PubMed Central

    Moon, Byeong-Ui; Hakimi, Navid; Hwang, Dae Kun; Tsai, Scott S. H.

    2014-01-01

    We present the conformal coating of non-spherical magnetic particles in a co-laminar flow microfluidic system. Whereas in the previous reports spherical particles had been coated with thin films that formed spheres around the particles; in this article, we show the coating of non-spherical particles with coating layers that are approximately uniform in thickness. The novelty of our work is that while liquid-liquid interfacial tension tends to minimize the surface area of interfaces—for example, to form spherical droplets that encapsulate spherical particles—in our experiments, the thin film that coats non-spherical particles has a non-minimal interfacial area. We first make bullet-shaped magnetic microparticles using a stop-flow lithography method that was previously demonstrated. We then suspend the bullet-shaped microparticles in an aqueous solution and flow the particle suspension with a co-flow of a non-aqueous mixture. A magnetic field gradient from a permanent magnet pulls the microparticles in the transverse direction to the fluid flow, until the particles reach the interface between the immiscible fluids. We observe that upon crossing the oil-water interface, the microparticles become coated by a thin film of the aqueous fluid. When we increase the two-fluid interfacial tension by reducing surfactant concentration, we observe that the particles become trapped at the interface, and we use this observation to extract an approximate magnetic susceptibility of the manufactured non-spherical microparticles. Finally, using fluorescence imaging, we confirm the uniformity of the thin film coating along the entire curved surface of the bullet-shaped particles. To the best of our knowledge, this is the first demonstration of conformal coating of non-spherical particles using microfluidics. PMID:25332731

  12. Boron coating on boron nitride coated nuclear fuels by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Durmazuçar, Hasan H.; Gündüz, Güngör

    2000-12-01

    Uranium dioxide-only and uranium dioxide-gadolinium oxide (5% and 10%) ceramic nuclear fuel pellets which were already coated with boron nitride were coated with thin boron layer by chemical vapor deposition to increase the burn-up efficiency of the fuel during reactor operation. Coating was accomplished from the reaction of boron trichloride with hydrogen at 1250 K in a tube furnace, and then sintering at 1400 and 1525 K. The deposited boron was identified by infrared spectrum. The morphology of the coating was studied by using scanning electron microscope. The plate, grainy and string (fiber)-like boron structures were observed.

  13. High-Power Diode Laser Surface Treated HVOF Coating to Combat High Energy Particle Impact Wear

    NASA Astrophysics Data System (ADS)

    Mann, B. S.; Arya, Vivek; Pant, B. K.

    2013-07-01

    High-velocity oxy-fuel (HVOF)-sprayed coatings have performed exceptionally well in low-energy particle impact wear and are accepted worldwide. However, their application for high-energy particle impact wear (HEPIW) requires a different approach and more efforts. HVOF-coating systems typically use WC-Co, WC-Co-Cr, WC-Ni-Cr, and FeCrAlY-Cr3C2 powders. WC-Co-Cr powders are preferred when there is a high demand for corrosion resistance. WC-10Co-4Cr coating powder has been selected in the current study. To improve coating properties such as microhardness, fracture toughness, and HEPIW resistance, a new approach of surface treatment with robotically controlled high-power diode laser (HPDL) is attempted. The robotically controlled HVOF-coating deposition and laser surface treatment were monitored using real-time diagnostic control. The HPDL-treated coating has been compared with "as-sprayed" HVOF coating for HEPIW resistance, fracture toughness, microhardness and microstructure. The coating characteristics and properties after laser surface treatment have improved many times compared with "as-sprayed" HVOF coating. This is due to the elimination of pores in the coating and formation of a metallurgical bond between coating and substrate. This new development opens up a possibility of using such laser treatments in specialized areas where HEPIW damages are acute. The fracture toughness and HEPIW resistance along with optical micrographs of HPDL-treated and untreated HVOF coatings are discussed and reported in this article. HEPIW resistance is observed to be proportional to the product of fracture toughness and microhardness of the HVOF coating.

  14. Effect of carbon coating on scuffing performance in diesel fuels

    SciTech Connect

    Ajayi, O. O.; Alzoubi, M. F.; Erdemir, A.; Fenske, G. R.

    2000-06-29

    Low-sulfur and low-aromatic diesel fuels are being introduced in order to reduce various types of emissions in diesel engines to levels in compliance with current and impending US federal regulations. The low lubricity of these fuels, however, poses major reliability and durability problems for fuel injection components that depend on diesel fuel for their lubrication. In the present study, the authors evaluated the scuff resistance of surfaces in regular diesel fuel containing 500 ppm sulfur and in Fischer-Tropsch synthetic diesel fuel containing no sulfur or aromatics. Tests were conducted with the high frequency reciprocating test rig (HFRR) using 52100 steel balls and H-13 tool-steel flats with and without Argonne's special carbon coatings. Test results showed that the sulfur-containing fuels provide about 20% higher scuffing resistance than does fuel without sulfur. Use of the carbon coating on the flat increased scuffing resistance in both regular and synthetic fuels by about ten times, as measured by the contact severity index at scuffing. Scuffing failure in tests conducted with coated surfaces did not occur until the coating had been removed by the two distinct mechanisms of spalling and wear.

  15. Design of Aerosol Particle Coating: Thickness, Texture and Efficiency

    PubMed Central

    Buesser, B.; Pratsinis, S.E.

    2013-01-01

    Core-shell particles preserve the performance (e.g. magnetic, plasmonic or opacifying) of a core material while modifying its surface with a shell that facilitates (e.g. by blocking its reactivity) their incorporation into a host liquid or polymer matrix. Here coating of titania (core) aerosol particles with thin silica shells (films or layers) is investigated at non-isothermal conditions by a trimodal aerosol dynamics model, accounting for SiO2 generation by gas phase and surface oxidation of hexamethyldisiloxane (HMDSO) vapor, coagulation and sintering. After TiO2 particles have reached their final primary particle size (e.g. upon completion of sintering during their flame synthesis), coating starts by uniformly mixing them with HMDSO vapor that is oxidized either in the gas phase or on the particles’ surface resulting in SiO2 aerosols or deposits, respectively. Sintering of SiO2 deposited onto the core TiO2 particles takes place transforming rough into smooth coating shells depending on process conditions. The core-shell characteristics (thickness, texture and efficiency) are calculated for two limiting cases of coating shells: perfectly smooth (e.g. hermetic) and fractal-like. At constant TiO2 core particle production rate, the influence of coating weight fraction, surface oxidation and core particle size on coating shell characteristics is investigated and compared to pertinent experimental data through coating diagrams. With an optimal temperature profile for complete precursor conversion, the TiO2 aerosol and SiO2-precursor (HMDSO) vapor concentrations have the strongest influence on product coating shell characteristics. PMID:23729833

  16. Influence of Processing Parameters on Residual Stress of High Velocity Oxy-Fuel Thermally Sprayed WC-Co-Cr Coating

    NASA Astrophysics Data System (ADS)

    Gui, M.; Eybel, R.; Asselin, B.; Radhakrishnan, S.; Cerps, J.

    2012-10-01

    Residual stress in high velocity oxy-fuel (HVOF) thermally sprayed WC-10Co-4Cr coating was studied based on design of experiment (DOE) with five factors of oxygen flow, fuel gas hydrogen flow, powder feed rate, stand-off distance, and surface speed of substrate. In each DOE run, the velocity and temperature of in-flight particle in flame, and substrate temperature were measured. Almen-type N strips were coated, and their deflections after coating were used for evaluation of residual stress level in the coating. The residual stress in the coating obtained in all DOE runs is compressive. In the present case of HVOF thermally sprayed coating, the residual stress is determined by three types of stress: peening, quenching, and cooling stress generated during spraying or post spraying. The contribution of each type stress to the final compressive residual stress in the coating depends on material properties of coating and substrate, velocity and temperature of in-flight particle, and substrate temperature. It is found that stand-off distance is the most important factor to affect the final residual stress in the coating, following by two-factor interaction of oxygen flow and hydrogen flow. At low level of stand-off distance, higher velocity of in-flight particle in flame and higher substrate temperature post spraying generate more peening stress and cooling stress, resulting in higher compressive residual stress in the coating.

  17. M3FT-15OR0202237: Submit Report on Results From Initial Coating Layer Development For UN TRISO Particles

    SciTech Connect

    Jolly, Brian C.; Lindemer, Terrence; Terrani, Kurt A.

    2015-02-01

    In support of fully ceramic matrix (FCM) fuel development, coating development work has begun at the Oak Ridge National Laboratory (ORNL) to produce tri-isotropic (TRISO) coated fuel particles with UN kernels. The nitride kernels are used to increase heavy metal density in these SiC-matrix fuel pellets with details described elsewhere. The advanced gas reactor (AGR) program at ORNL used fluidized bed chemical vapor deposition (FBCVD) techniques for TRISO coating of UCO (two phase mixture of UO2 and UCx) kernels. Similar techniques were employed for coating of the UN kernels, however significant changes in processing conditions were required to maintain acceptable coating properties due to physical property and dimensional differences between the UCO and UN kernels.

  18. A novel concept of QUADRISO particles Part III : applications to the plutonium-thorium fuel cycle.

    SciTech Connect

    Talamo, A.

    2009-03-01

    In the present study, a plutonium-thorium fuel cycle is investigated including the {sup 233}U production and utilization. A prismatic thermal High Temperature Gas Reactor (HTGR) and the novel concept of quadruple isotropic (QUADRISO) coated particles, designed at the Argonne National Laboratory, have been used for the study. In absorbing QUADRISO particles, a burnable poison layer surrounds the central fuel kernel to flatten the reactivity curve as a function of time. At the beginning of life, the fuel in the QUADRISO particles is hidden from neutrons, since they get absorbed in the burnable poison before they reach the fuel kernel. Only when the burnable poison depletes, neutrons start streaming into the fuel kernel inducing fission reactions and compensating the fuel depletion of ordinary TRISO particles. In fertile QUADRISO particles, the absorber layer is replaced by natural thorium with the purpose of flattening the excess of reactivity by the thorium resonances and producing {sup 233}U. The above configuration has been compared with a configuration where fissile (neptunium-plutonium oxide from Light Water Reactors irradiated fuel) and fertile (natural thorium oxide) fuels are homogeneously mixed in the kernel of ordinary TRISO particles. For the {sup 233}U utilization, the core has been equipped with europium oxide absorbing QUADRISO particles.

  19. Method of producing encapsulated thermonuclear fuel particles

    DOEpatents

    Smith, Warren H.; Taylor, William L.; Turner, Harold L.

    1976-01-01

    A method of producing a fuel particle is disclosed, which comprises forming hollow spheroids which have a mass number greater than 50, immersing said spheroids while under the presence of pressure and heat in a gaseous atmosphere containing an isotope, such as deuterium and tritium, so as to diffuse the gas into the spheroid and thereafter cooling said spheroids up to about 77.degree. Kelvin to about 4.degree. Kelvin.

  20. FROST - FReezing Of coated and uncoated duST particles

    NASA Astrophysics Data System (ADS)

    Wex, H.

    2009-04-01

    In April 2008, the measurement campaign FROST (FReezing Of coated and uncoated duST particles) was conducted at the ACCENT (Atmospheric Composition Change - the European NeTwork of excellence) infrastructure site LACIS (Leipzig Aerosol Cloud Interaction Simulator). During the campaign, size selected coated and uncoated Arizona Test Dust (ATD) particles were characterized with respect to shape, chemical composition, hygroscopic growth and activation, and their ability to act as IN (Ice Nuclei). The ATD particles were dispersed by means of a fluidized bed generator. Coatings were applied in different furnaces, operated at different temperatures. The coatings were either succinic acid, sulphuric acid, or ammonium sulphate. A DMA (Differential Mobility Analyzer) was used for selecting particles with a mobility diameter of 300 nm. The following measurements were done: Three AMS (Aerosol Mass Spectrometers, e.g. Schneider et al. (2005) and references therein) were used to determine particle composition. Particles were collected on grids for subsequent TEM (Transmission Electron Micoscropy) analysis. Hygroscopic growth factors were determined by means of a HH-TDMA (High Humidity Tandem Differential Mobility Analyzer) that measured up to relative humidities (RH) of 98% (Hennig et al. (2005)). The critical super-saturations needed for the activation of the investigated particles into cloud droplets were measured with a continuous flow CCNc (Cloud Condensation Nucleus counter) from DMT (Droplet Measurement Technologies, Roberts and Nenes (2005)). The LACIS flow tube was extended to a length of 8 m, so LACIS could be used to examine the immersion freezing behaviour of the coated and uncoated ATD particles. By a bulk analysis and by the AMS measurements, the ATD particles were found to contain water soluble material, however in small quantities. By means of the online AMS measurements, it was possible to distinguish between thin and thick H2SO4 coatings. For the thin coatings

  1. Molten carbonate fuel cell cathode with mixed oxide coating

    DOEpatents

    Hilmi, Abdelkader; Yuh, Chao-Yi

    2013-05-07

    A molten carbonate fuel cell cathode having a cathode body and a coating of a mixed oxygen ion conductor materials. The mixed oxygen ion conductor materials are formed from ceria or doped ceria, such as gadolinium doped ceria or yttrium doped ceria. The coating is deposited on the cathode body using a sol-gel process, which utilizes as precursors organometallic compounds, organic and inorganic salts, hydroxides or alkoxides and which uses as the solvent water, organic solvent or a mixture of same.

  2. Fluorinated raspberry-like polymer particles for superamphiphobic coatings.

    PubMed

    Jiang, Weijie; Grozea, Claudia M; Shi, Zengqian; Liu, Guojun

    2014-02-26

    Raspberry-like (RB) polymer particles were prepared, fluorinated, and cast onto glass plates to yield highly water- and oil-repellant superamphiphobic particulate coatings. To procure the RB particles, glycidyl-bearing 212 and 332 nm particles (abbreviated as s-GMA and l-GMA, respectively) were first prepared via surfactant-free free radical emulsion polymerization. Reacting the glycidyl groups of the l-GMA particles with 2,2'-(ethylenedioxy)bis(ethylamine) (EDEA) produced large amine-functionalized particles (l-NH2). The l-NH2 particles were then reacted with an excess of the s-GMA particles to create RB particles. For surface fluorination, the residual glycidyl groups of the smaller s-GMA particles surrounding the central l-NH2 core of the RB particles were first converted to amino groups by reaction with EDEA. The purified amino-bearing particles were subsequently reacted with an excess of a statistical copolymer poly(2-(perfluorooctyl)ethyl methacrylate-co-glycidyl methacrylate), P(FOEMA-co-GMA). Casting these particles onto glass plates yielded particulate films that exhibited static contact angles of 165 ± 2°, 155 ± 3°, 152 ± 4°, and 143 ± 1° and droplet rolling angles of <1 °, <1 °, 7 ± 2°, and 13 ± 2° for water, diiodomethane, corn-based cooking oil, and hexadecane droplets, respectively. These results demonstrated that this practical bottom-up approach could be used to produce superamphiphobic coatings.

  3. Dry particle coating of polymer particles for tailor-made product properties

    SciTech Connect

    Blümel, C. Schmidt, J. Dielesen, A. Sachs, M. Winzer, B. Peukert, W. Wirth, K.-E.

    2014-05-15

    Disperse polymer powders with tailor-made particle properties are of increasing interest in industrial applications such as Selective Laser Beam Melting processes (SLM). This study focuses on dry particle coating processes to improve the conductivity of the insulating polymer powder in order to assemble conductive devices. Therefore PP particles were coated with Carbon Black nanoparticles in a dry particle coating process. This process was investigated in dependence of process time and mass fraction of Carbon Black. The conductivity of the functionalized powders was measured by impedance spectroscopy. It was found that there is a dependence of process time, respectively coating ratio and conductivity. The powder shows higher conductivities with increasing number of guest particles per host particle surface area, i.e. there is a correlation between surface functionalization density and conductivity. The assembled composite particles open new possibilities for processing distinct polymers such as PP in SLM process. The fundamentals of the dry particle coating process of PP host particles with Carbon Black guest particles as well as the influence on the electrical conductivity will be discussed.

  4. Dry particle coating of polymer particles for tailor-made product properties

    NASA Astrophysics Data System (ADS)

    Blümel, C.; Schmidt, J.; Dielesen, A.; Sachs, M.; Winzer, B.; Peukert, W.; Wirth, K.-E.

    2014-05-01

    Disperse polymer powders with tailor-made particle properties are of increasing interest in industrial applications such as Selective Laser Beam Melting processes (SLM). This study focuses on dry particle coating processes to improve the conductivity of the insulating polymer powder in order to assemble conductive devices. Therefore PP particles were coated with Carbon Black nanoparticles in a dry particle coating process. This process was investigated in dependence of process time and mass fraction of Carbon Black. The conductivity of the functionalized powders was measured by impedance spectroscopy. It was found that there is a dependence of process time, respectively coating ratio and conductivity. The powder shows higher conductivities with increasing number of guest particles per host particle surface area, i.e. there is a correlation between surface functionalization density and conductivity. The assembled composite particles open new possibilities for processing distinct polymers such as PP in SLM process. The fundamentals of the dry particle coating process of PP host particles with Carbon Black guest particles as well as the influence on the electrical conductivity will be discussed.

  5. Reaction synthesis of Ni-Al based particle composite coatings

    SciTech Connect

    SUSAN,DONALD F.; MISIOLEK,WOICECK Z.; MARDER,ARNOLD R.

    2000-02-11

    Electrodeposited metal matrix/metal particle composite (EMMC) coatings were produced with a nickel matrix and aluminum particles. By optimizing the process parameters, coatings were deposited with 20 volume percent aluminum particles. Coating morphology and composition were characterized using light optical microscopy (LOM), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). Differential thermal analysis (DTA) was employed to study reactive phase formation. The effect of heat treatment on coating phase formation was studied in the temperature range 415 to 1,000 C. Long-time exposure at low temperature results in the formation of several intermetallic phases at the Ni matrix/Al particle interfaces and concentrically around the original Al particles. Upon heating to the 500--600 C range, the aluminum particles react with the nickel matrix to form NiAl islands within the Ni matrix. When exposed to higher temperatures (600--1,000 C), diffusional reaction between NiAl and nickel produces ({gamma})Ni{sub 3}Al. The final equilibrium microstructure consists of blocks of ({gamma}{prime})Ni{sub 3}Al in a {gamma}(Ni) solid solution matrix, with small pores also present. Pore formation is explained based on local density changes during intermetallic phase formation and microstructural development is discussed with reference to reaction synthesis of bulk nickel aluminides.

  6. CCN activation of pure and coated carbon black particles.

    PubMed

    Dusek, U; Reischl, G P; Hitzenberger, R

    2006-02-15

    The CCN (cloud condensation nucleus) activation of pure and coated carbon black particles was investigated using the University of Vienna cloud condensation nuclei counter (Giebl, H.; Berner, A.; Reischl, G.; Puxbaum, H.; Kasper-Giebl, A.; Hitzenberger, R. J. Aerosol Sci. 2002, 33, 1623-1634). The particles were produced by nebulizing an aqueous suspension of carbon black in a Collison atomizer. The activation of pure carbon black particles was found to require higher supersaturations than predicted by calculations representing the particles as insoluble, wettable spheres with mobility equivalent diameter. To test whether this effect is an artifact due to heating of the light-absorbing carbon black particles in the laser beam, experiments at different laser powers were conducted. No systematic dependence of the activation of pure carbon black particles on laser power was observed. The observations could be modeled using spherical particles and an effective contact angle of 4-6 degrees of water at their surface. The addition of a small amount of NaCl to the carbon black particles (by adding 5% by mass NaCl to the carbon black suspension) greatly enhanced their CCN efficiency. The measured CCN efficiencies were consistent with Kohler theory for particles consisting of insoluble and hygroscopic material. However, coating the carbon black particles with hexadecanol (a typical film-forming compound with one hydrophobic and one hydrophilic end) efficiently suppressed the CCN activation of the carbon black particles.

  7. Debye series for light scattering by a coated nonspherical particle

    SciTech Connect

    Xu Feng; Lock, James A.

    2010-06-15

    By using the extended boundary condition method, the Debye series is developed for light scattered by a coated nonspherical particle in order to interpret the angular dependence of the scattered intensity in terms of various physical processes. Numerical calculations are performed to study the influence of the coating thickness and the ellipticity of a coated spheroid on the angular position of the {alpha} and {beta} primary rainbows, which are produced by partial waves experiencing one internal reflection. The hyperbolic umbilic focal section is demonstrated and is analyzed for both the {alpha} and the {beta} rainbows.

  8. Debye series for light scattering by a coated nonspherical particle

    NASA Astrophysics Data System (ADS)

    Xu, Feng; Lock, James A.

    2010-06-01

    By using the extended boundary condition method, the Debye series is developed for light scattered by a coated nonspherical particle in order to interpret the angular dependence of the scattered intensity in terms of various physical processes. Numerical calculations are performed to study the influence of the coating thickness and the ellipticity of a coated spheroid on the angular position of the α and β primary rainbows, which are produced by partial waves experiencing one internal reflection. The hyperbolic umbilic focal section is demonstrated and is analyzed for both the α and the β rainbows.

  9. Polymer coatings as separator layers for microbial fuel cell cathodes

    NASA Astrophysics Data System (ADS)

    Watson, Valerie J.; Saito, Tomonori; Hickner, Michael A.; Logan, Bruce E.

    2011-03-01

    Membrane separators reduce oxygen flux from the cathode into the anolyte in microbial fuel cells (MFCs), but water accumulation and pH gradients between the separator and cathode reduces performance. Air cathodes were spray-coated (water-facing side) with anion exchange, cation exchange, and neutral polymer coatings of different thicknesses to incorporate the separator into the cathode. The anion exchange polymer coating resulted in greater power density (1167 ± 135 mW m-2) than a cation exchange coating (439 ± 2 mW m-2). This power output was similar to that produced by a Nafion-coated cathode (1114 ± 174 mW m-2), and slightly lower than the uncoated cathode (1384 ± 82 mW m-2). Thicker coatings reduced oxygen diffusion into the electrolyte and increased coulombic efficiency (CE = 56-64%) relative to an uncoated cathode (29 ± 8%), but decreased power production (255-574 mW m-2). Electrochemical characterization of the cathodes ex situ to the MFC showed that the cathodes with the lowest charge transfer resistance and the highest oxygen reduction activity produced the most power in MFC tests. The results on hydrophilic cathode separator layers revealed a trade off between power and CE. Cathodes coated with a thin coating of anion exchange polymer show promise for controlling oxygen transfer while minimally affecting power production.

  10. Coated metal sintering carriers for fuel cell electrodes

    DOEpatents

    Donelson, R.; Bryson, E.S.

    1998-11-10

    A carrier is described for conveying components of a fuel cell to be sintered through a sintering furnace. The carrier comprises a metal sheet coated with a water-based carbon paint, the water-based carbon paint comprising water, powdered graphite, an organic binder, a wetting agent, a dispersing agent and a defoaming agent.

  11. Coated metal sintering carriers for fuel cell electrodes

    SciTech Connect

    Donelson, Richard; Bryson, E. S.

    1998-01-01

    A carrier for conveying components of a fuel cell to be sintered through a sintering furnace. The carrier comprises a metal sheet coated with a water-based carbon paint, the water-based carbon paint comprising water, powdered graphite, an organic binder, a wetting agent, a dispersing agent and a defoaming agent.

  12. Characteristics of MCrAlY coatings sprayed by high velocity oxygen-fuel spraying system

    SciTech Connect

    Itoh, Y.; Saitoh, M.; Tamura, M.

    2000-01-01

    High velocity oxygen-fuel (HVOF) spraying system in open air has been established for producing the coatings that are extremely clean and dense. It is thought that the HVOF sprayed MCrAlY (M is Fe, Ni and/or Co) coatings can be applied to provide resistance against oxidation and corrosion to the hot parts of gas turbines. Also, it is well known that the thicker coating can be sprayed in comparison with any other thermal spraying systems due to improved residual stresses. However, thermal and mechanical properties of HVOF coatings have not been clarified. Especially, the characteristics of residual stress, that are the most important property from the view point of production technique, have not been made clear. In this paper, the mechanical properties of HVOF sprayed MCrAlY coatings were measured in both the case of as-sprayed and heat-treated coatings in comparison with a vacuum plasma sprayed MCrAlY coatings. It was confirmed that the mechanical properties of HVOF sprayed MCrAlY coatings could be improved by a diffusion heat treatment to equate the vacuum plasma sprayed MCrAlY coatings. Also, the residual stress characteristics were analyzed using a deflection measurement technique and a X-ray technique. The residual stress of HVOF coating was reduced by the shot-peening effect comparable to that of a plasma spray system in open air. This phenomena could be explained by the reason that the HVOF sprayed MCrAlY coating was built up by poorly melted particles.

  13. Conformal coating of non-spherical magnetic particles using microfluidics

    NASA Astrophysics Data System (ADS)

    Moon, Byeong-Ui; Hakimi, Navid; Hwang, Dae Kun; Tsai, Scott; Department of Mechanical; Industrial Engineering Team; Department of Chemical Engineering Collaboration

    2014-11-01

    We present the conformal coating of non-spherical magnetic particles in a microfluidic channel. We first prepare three-dimensional (3D) bullet-shaped magnetic microparticles using stop-flow lithography. We then suspend the bullet-shaped microparticles in an aqueous solution, and flow the particle suspension with a co-flow of a non-aqueous mixture. A magnetic field gradient from a permanent magnet pulls the microparticles in the transverse direction to the fluid flow, until the particles reach the interface between the immiscible fluids. In a physical domain characterized by a low particle Reynolds number and a high magnetic Bond number, we observe that the microparticles cross the oil-water interface, and then become coated by a thin film of the aqueous fluid. When we increase the two-fluid interfacial tension by reducing the surfactant concentration, we observe that the particles become trapped at the interface. We use this observation to approximate the magnetic susceptibility of the manufactured non-spherical microparticles, which are not known a priori. Using fluorescence imaging, we confirm the uniformity of the thin film coating along the surface of the bullet-shaped particles.

  14. Controlling the scattering properties of thin, particle-doped coatings

    NASA Astrophysics Data System (ADS)

    Rogers, William; Corbett, Madeleine; Manoharan, Vinothan

    2013-03-01

    Coatings and thin films of small particles suspended in a matrix possess optical properties that are important in several industries from cosmetics and paints to polymer composites. Many of the most interesting applications require coatings that produce several bulk effects simultaneously, but it is often difficult to rationally formulate materials with these desired optical properties. Here, we focus on the specific challenge of designing a thin colloidal film that maximizes both diffuse and total hemispherical transmission. We demonstrate that these bulk optical properties follow a simple scaling with two microscopic length scales: the scattering and transport mean free paths. Using these length scales and Mie scattering calculations, we generate basic design rules that relate scattering at the single particle level to the film's bulk optical properties. These ideas will be useful in the rational design of future optically active coatings.

  15. Polar studies of the sphericity degree of V/HTR nuclear fuel particles

    SciTech Connect

    Robert-Inacio, F. . E-mail: frederique.robert@isen.fr; Boschet, C.; Charollais, F.

    2006-06-15

    Advanced nuclear power reactor designs such as (Very) High Temperature Reactors (V/HTR) employ TRISO fuel particles that typically have a sub-millimetre U-based fuel kernel coated with three isotropic ceramic layers-a layer of silicon carbide sandwiched between pyrocarbon layers of different density. Evaluation of the ceramic layer thickness and of the degree of sphericity of these typical nuclear fuel particles is required at each step of the fabrication, in order to estimate future fuel performance under irradiation conditions. This study is based on the image processing of polished cross-sections, realized near the equatorial plane. From these 2D images, some measurements are carried out, giving an estimation of the diameter values for a sample of particles at each step of the coating process. These values are then statistically extended to the third dimension in order to obtain the thickness of each layer and the degree of sphericity of each particle. A representation of diameter and layer thickness in polar coordinates enables one to identify steps for which the coating process is defective or deviating from nominal objectives.

  16. Data Compilation for AGR-3/4 Designed-to-Fail (DTF) Fuel Particle Batch LEU04-02DTF

    SciTech Connect

    Hunn, John D; Miller, James Henry

    2008-10-01

    This document is a compilation of coating and characterization data for the AGR-3/4 designed-to-fail (DTF) particles. The DTF coating is a high density, high anisotropy pyrocarbon coating of nominal 20 {micro}m thickness that is deposited directly on the kernel. The purpose of this coating is to fail early in the irradiation, resulting in a controlled release of fission products which can be analyzed to provide data on fission product transport. A small number of DTF particles will be included with standard TRISO driver fuel particles in the AGR-3 and AGR-4 compacts. The ORNL Coated Particle Fuel Development Laboratory 50-mm diameter fluidized bed coater was used to coat the DTF particles. The coatings were produced using procedures and process parameters that were developed in an earlier phase of the project as documented in 'Summary Report on the Development of Procedures for the Fabrication of AGR-3/4 Design-to-Fail Particles', ORNL/TM-2008/161. Two coating runs were conducted using the approved coating parameters. NUCO425-06DTF was a final process qualification batch using natural enrichment uranium carbide/uranium oxide (UCO) kernels. After the qualification run, LEU04-02DTF was produced using low enriched UCO kernels. Both runs were inspected and determined to meet the specifications for DTF particles in section 5 of the AGR-3 & 4 Fuel Product Specification (EDF-6638, Rev.1). Table 1 provides a summary of key properties of the DTF layer. For comparison purposes, an archive sample of DTF particles produced by General Atomics was characterized using identical methods. This data is also summarized in Table 1.

  17. Composite of ceramic-coated magnetic alloy particles

    DOEpatents

    Moorhead, Arthur J.; Kim, Hyoun-Ee

    2000-01-01

    A composite structure and method for manufacturing same, the composite structure being comprised of metal particles and an inorganic bonding media. The method comprises the steps of coating particles of a metal powder with a thin layer of an inorganic bonding media selected from the group of powders consisting of a ceramic, glass, and glass-ceramic. The particles are assembled in a cavity and heat, with or without the addition of pressure, is thereafter applied to the particles until the layer of inorganic bonding media forms a strong bond with the particles and with the layer of inorganic bonding media on adjacent particles. The resulting composite structure is strong and remains cohesive at high temperatures.

  18. Glass coated compressible solid oxide fuel cell seals

    NASA Astrophysics Data System (ADS)

    Rautanen, M.; Thomann, O.; Himanen, O.; Tallgren, J.; Kiviaho, J.

    2014-02-01

    With the growing footprint of solid oxide fuel cell stacks, there is a need to extend the operating range of compressible gaskets towards lower stress levels. This article describes a method to manufacture SOFC seals by coating a compressible sealing material (Thermiculite 866) with glass to obtain good sealing performance even at compression stresses as low as 0.1 MPa. Glass layer can be coated using an organic carrier consisting of terpineol, ethanol and ethyl cellulose. The coated seals can be heat treated by simply ramping the temperature up to operating temperature at 60 Kh-1 and therefore no extra steps, which are typical to glass seals, are required. Coated seals were manufactured using this route and evaluated both ex-situ and in a real stack. Leak rates of 0.1-0.3 ml (m min)-1 were measured at 2-25 mbar overpressure using 50/50 H2/N2. A 30-cell stack was manufactured and tested using coated seals. At nominal operating conditions of 0.25 A cm-2 and 650 °C average cathode temperature, 46% fuel utilization and 20% air utilization the stack had a total hydrogen cross leak of 60 ml min-1 corresponding to 0.7% of the inlet hydrogen flow rate.

  19. TRISO-Coated Fuel Durability Under Extreme Conditions

    SciTech Connect

    Reimanis, Ivar; Gorman, Brian; Butt, Darryl

    2014-03-30

    The PIs propose to examine TRISO-coated particles (SiC and ZrC coatings) in an integrated two-part study. In the first part, experiments will be performed to assess the reaction kinetics of the carbides under CO-CO2 environments at temperatures up to 1800 degree C. Kinetic model will be applied to describe the degradation. Scanning and transmission electron microscopy will be employed to establish the chemical and microstructure evolution under the imposed environmental conditions. The second part of the proposed work focuses on establishing the role of the high temperature, environmental exposure described above on the mechanical behavior of TRISO-coated particles. Electron microscopy and other advanced techniques will be subsequently performed to evaluate failure mechanisms. The work is expected to reveal relationships between corrosion reactions, starting material characteristics (polytype of SiC, impurity concentration, flaw distribution), flaw healing behavior, and crack growth.

  20. A conductive and hydrophilic bipolar plate coating for enhanced proton exchange membrane fuel cell performance and water management

    NASA Astrophysics Data System (ADS)

    Nowak, Andrew P.; Salguero, Tina T.; Kirby, Kevin W.; Zhong, Feng; Blunk, Richard H. J.

    2012-07-01

    Electrically conductive and hydrophilic coatings for proton exchange membrane fuel cell (PEMFC) stainless steel bipolar plates have been developed in order to minimize voltage losses at the plate and gas diffusion layer (GDL) interface and facilitate liquid water transport in plate channels for efficient stack operation. The coatings are based on a multifunctional silane, 1,2-bis(triethoxysilyl)ethane (BTSE), mixed with conductive, hydrophilic carbon black. Vulcan® XC72 carbon black was modified with either polar phenylsulfonic acid (PSA) or carboxylic acid (COOH) groups to increase hydrophilic character and wetting behavior. Wetting and electrical contact resistance performance was compared with coatings based on nano-particle titania and silica. These conductive silane and carbon composite coating precursors are conveniently formulated in alcohol solution for scalable application via spray coating. Cured films exhibit negligible contact resistance increase (<2 mΩ cm2) at 1.4 MPa when deposited on both physical vapor deposited (PVD) carbon and electroplated gold coated stainless steel. The coatings were tested for hydrophilicity retention under wet and dry fuel cell conditions where the BTSE-COOH coating remained hydrophilic on stamped stainless steel bipolar plate prototypes after greater than 1200 h of simulated fuel cell testing with only moderate loss of hydrophilicity.

  1. Interactions between protein coated particles and polymer surfaces studied with the rotating particles probe.

    PubMed

    Kemper, M; Spridon, D; van IJzendoorn, L J; Prins, M W J

    2012-05-29

    Nonspecific interactions between proteins and polymer surfaces have to be minimized in order to control the performance of biosensors based on immunoassays with particle labels. In this paper we investigate these nonspecific interactions by analyzing the response of protein coated magnetic particles to a rotating magnetic field while the particles are in nanometer vicinity to a polymer surface. We use the fraction of nonrotating (bound) particles as a probe for the interaction between the particles and the surface. As a model system, we study the interaction of myoglobin coated particles with oxidized polystyrene surfaces. We measure the interaction as a function of the ionic strength of the solution, varying the oxidation time of the polystyrene and the pH of the solution. To describe the data we propose a model in which particles bind to the polymer by crossing an energy barrier. The height of this barrier depends on the ionic strength of the solution and two interaction parameters. The fraction of nonrotating particles as a function of ionic strength shows a characteristic shape that can be explained with a normal distribution of energy barrier heights. This method to determine interaction parameters paves the way for further studies to quantify the roles of protein coated particles and polymers in their mutual nonspecific interactions in different matrixes.

  2. Cold sprayed copper coating: numerical study of particle impact and coating characterization

    NASA Astrophysics Data System (ADS)

    Mebdoua, Yamina; Fizi, Yazid; Bouhelal, Nadjet

    2016-05-01

    Cold spraying technique is a promising process fabricating high quality metallic coatings. This work concerns both numerical and experimental investigations of cold sprayed copper coating taking into account impact conditions including, particle velocities and temperature, gas pressure and material nature. The conducted numerical study is an examination of the deformation behavior of Cu particles sprayed onto steel substrate using Abaqus/explicit software, allowing a good understanding of the deposition characteristics of copper particles and the effect of particle velocity on the coating microstructure. The numerical results show that particle impact velocity has a significant effect on its morphology; Lagrangian method exhibits an excessive distortion of the elements in the case of high impact velocity and fine meshing size, whereas simulation of particle impact using arbitrary Lagrangian-Eulerian (ALE) method is close to the experimental observations. Contribution to the topical issue "Materials for Energy Harvesting, Conversion and Storage (ICOME 2015) - Elected submissions", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

  3. Particle fueling and impurity control in PDX

    SciTech Connect

    Fonck, R.J.; Bell, M.; Bol, K.; Budny, R.; Couture, P.; Darrow, D.; Dylla, H.; Goldston, R.; Grek, B.; Hawryluk, R.

    1984-12-01

    Fueling requirements and impurity levels in neutral-beam-heated discharges in the PDX tokamak have been compared for plasmas formed with conventional graphite rail limiters, a particle scoop limiter, and an open or closed poloidal divertor. Gas flows necessary to obtain a given density are highest for diverted discharges and lowest for the scoop limiter. Hydrogen pellet injection provides an efficient alternate fueling technique, and a multiple pellet injector has produced high density discharges for an absorbed neutral beam power of up to 600 kW, above which higher speeds or more massive pellets are required for penetration to the plasma core. Power balance studies indicate that 30 to 40% of the total input power is radiated while approx. 15% is absorbed by the limiting surface, except in the open divertor case, where 60% flows to the neutralizer plate. In all operating configurations, Z/sub eff/ usually rises at the onset of neutral beam injection. Both open divertor plasmas and those formed on a well conditioned water-cooled limiter have Z/sub eff/ less than or equal to 2 at the end of neutral injection. A definitive comparison of divertors and limiters for impurity control purposes requires longer beam pulses or higher power levels than available on present machines.

  4. Particle fueling and impurity control in PDX

    NASA Astrophysics Data System (ADS)

    Fonck, R. J.; Bell, M.; Bol, K.; Budny, R.; Couture, P.; Darrow, D.; Dylla, H.; Goldston, R.; Grek, B.; Hawryluk, R.; Ida, K.; Jaehnig, K.; Johnson, D.; Kaita, R.; Kaye, S.; Kugel, H.; Leblanc, B.; Mansfield, D.; Mcbride, T.; Mcguire, K.; Milora, S.; Mueller, D.; Okabayashi, M.; Owens, D.; Post, D.; Reusch, M.; Schmidt, G.; Sesnic, S.; Takahashi, H.; Tenney, F.; Ulrickson, M.

    1984-12-01

    Fueling requirements and impurity levels in neutral-beam-heated discharges in the PDX tokamak have been compared for plasmas formed with conventional graphite rail limiters, a particle scoop limiter, and an open or closed poloidal divertor. Gas flows necessary to obtain a given density are highest for diverted discharges and lowest for the scoop limiter. Hydrogen pellet injection provides an efficient alternative fueling technique, and a multiple pellet injector has produced high density discharges for an absorbed neutral beam power of up to 600 kW, above which higher speeds or more massive pellets are required for penetration to the plasma core. Power balance studies indicate that 30-40% of the total input power is radiated while ~15% is absorbed by the limiting surface, except in the open divertor case, where 60% flows to the neutralizer plate. In all operating configurations, Zeff usually rises at the onset of neutral beam injection. Both open divertor pl;asmas and those formed on a well conditioned water-cooled limiter have Zeff ⪅ 2 at the end of neutral injection. A definitive comparison of divertors and limiters for impurity control purposes requires longer beam pulses or higher power levels than available on present machines.

  5. Development of Yttrium Stabilized Zirconia (YSZ) diffusion barrier coatings for mitigation of Fuel-Cladding Chemical Interactions

    NASA Astrophysics Data System (ADS)

    Firouzdor, Vahid; Brechtl, Jamieson; Wilson, Lucas; Semerau, Brandon; Sridharan, Kumar; Allen, Todd R.

    2013-07-01

    Fuel-Cladding Chemical Interactions (FCCIs) in a nuclear reactor occurs due to thermal and radiation enhanced inter-diffusion between the cladding and fuel materials. This can have the detrimental effects of reducing the effective cladding wall thickness and the formation of low melting point eutectic compounds. Deposition of thin diffusion barrier coatings in the inner surface of the cladding can potentially reduce or delay the onset of FCCI. This study examines the feasibility of using nanofluid-based electrophoretic deposition (EPD) process to deposit coatings of Yttrium Stabilized Zirconia (YSZ) as the diffusion barrier coating. The deposition parameters, including the nanofluid solvent, additive, particle size, current, and voltage were optimized using test flat substrates of T91 ferritic-martensitic steel. A post deposition sintering step was also conducted and optimized to improve the bonding and mechanical integrity of the coating. Diffusion characteristics of the coatings were investigated by diffusion couple experiments using cerium as a fuel fission product responsible for solid state FCCI. These diffusion couple studies performed at 575 °C for 100 h showed that the YSZ coatings significantly reduced the solid state inter-diffusion between cerium and steel. A heat transfer model was developed to simulate the changes in temperature profile inside the fuel cladding by addition of YSZ coating. It was found that even though the temperature can increase in the coated cladding, the temperature falls below the melting point of uranium and eutectic temperature in Fe-U phase diagram. Using a co-axial configuration in conjunction with the EPD process, YSZ was successfully deposited uniformly on the inner surfaces of 12″ length sections of cladding with 4 mm inner diameter. Such a coating is extremely hard to make by conventional coating technologies like thermal spray or vapor deposition.

  6. HVOF Spraying of Fe-Based MMC Coatings with In Situ Formation of Hard Particles by Hot Isostatic Pressing

    NASA Astrophysics Data System (ADS)

    Röttger, A.; Weber, S. L.; Theisen, W.; Rajasekaran, B.; Vaßen, R.

    2012-03-01

    Thick (2-3 mm) Fe-base coatings with admixed ferrotitanium (Fe30Ti70) were applied to austenitic steel by a high-velocity oxy-fuel process (HVOF). Hot-isostatic pressing (HIP) was carried out to the decrease porosity and to increase the material strength, wear resistance, and adhesive bond strength of the deposited coating to the substrate material. SEM and XRD investigations confirmed the formation of hard titanium carbide (TiC) particles during HIP treatment as a result of strong carbon diffusion out of the metal matrix and into the Fe30Ti70 particles. The mechanical and wear properties of the densified coatings were investigated by means of shear tests, hardness measurements, and abrasive wear tests. A comparison of the coatings in the as-sprayed and the HIPed state showed a large increase in the wear resistance due to in situ TiC formation.

  7. Fission Product Monitoring of TRISO Coated Fuel For The Advanced Gas Reactor -1 Experiment

    SciTech Connect

    Dawn M. Scates; John K. Hartwell; John b. Walter

    2010-10-01

    The US Department of Energy has embarked on a series of tests of TRISO-coated particle reactor fuel intended for use in the Very High Temperature Reactor (VHTR) as part of the Advanced Gas Reactor (AGR) program. The AGR-1 TRISO fuel experiment, currently underway, is the first in a series of eight fuel tests planned for irradiation in the Advanced Test Reactor (ATR) located at the Idaho National Laboratory (INL). The AGR-1 experiment reached a peak compact averaged burn up of 9% FIMA with no known TRISO fuel particle failures in March 2008. The burnup goal for the majority of the fuel compacts is to have a compact averaged burnup greater than 18% FIMA and a minimum compact averaged burnup of 14% FIMA. At the INL the TRISO fuel in the AGR-1 experiment is closely monitored while it is being irradiated in the ATR. The effluent monitoring system used for the AGR-1 fuel is the Fission Product Monitoring System (FPMS). The FPMS is a valuable tool that provides near real-time data indicative of the AGR-1 test fuel performance and incorporates both high-purity germanium (HPGe) gamma-ray spectrometers and sodium iodide [NaI(Tl)] scintillation detector-based gross radiation monitors. To quantify the fuel performance, release-to-birth ratios (R/B’s) of radioactive fission gases are computed. The gamma-ray spectra acquired by the AGR-1 FPMS are analyzed and used to determine the released activities of specific fission gases, while a dedicated detector provides near-real time count rate information. Isotopic build up and depletion calculations provide the associated isotopic birth rates. This paper highlights the features of the FPMS, encompassing the equipment, methods and measures that enable the calculation of the release-to-birth ratios. Some preliminary results from the AGR-1 experiment are also presented.

  8. Fission Product Monitoring of TRISO Coated Fuel For The Advanced Gas Reactor -1 Experiment

    SciTech Connect

    Dawn M. Scates; John K Hartwell; John B. Walter

    2008-09-01

    The US Department of Energy has embarked on a series of tests of TRISO-coated particle reactor fuel intended for use in the Very High Temperature Reactor (VHTR) as part of the Advanced Gas Reactor (AGR) program. The AGR-1 TRISO fuel experiment, currently underway, is the first in a series of eight fuel tests planned for irradiation in the Advanced Test Reactor (ATR) located at the Idaho National Laboratory (INL). The AGR-1 experiment reached a peak compact averaged burn up of 9% FIMA with no known TRISO fuel particle failures in March 2008. The burnup goal for the majority of the fuel compacts is to have a compact averaged burnup greater than 18% FIMA and a minimum compact averaged burnup of 14% FIMA. At the INL the TRISO fuel in the AGR-1 experiment is closely monitored while it is being irradiated in the ATR. The effluent monitoring system used for the AGR-1 fuel is the Fission Product Monitoring System (FPMS). The FPMS is a valuable tool that provides near real-time data indicative of the AGR-1 test fuel performance and incorporates both high-purity germanium (HPGe) gamma-ray spectrometers and sodium iodide [NaI(Tl)] scintillation detector-based gross radiation monitors. To quantify the fuel performance, release-to-birth ratios (R/B’s) of radioactive fission gases are computed. The gamma-ray spectra acquired by the AGR-1 FPMS are analyzed and used to determine the released activities of specific fission gases, while a dedicated detector provides near-real time count rate information. Isotopic build up and depletion calculations provide the associated isotopic birth rates. This paper highlights the features of the FPMS, encompassing the equipment, methods and measures that enable the calculation of the release-to-birth ratios. Some preliminary results from the AGR-1 experiment are also presented.

  9. Fuel swelling and interaction layer formation in the SELENIUM Si and ZrN coated U(Mo) dispersion fuel plates irradiated at high power in BR2

    NASA Astrophysics Data System (ADS)

    Leenaers, A.; Van den Berghe, S.; Koonen, E.; Kuzminov, V.; Detavernier, C.

    2015-03-01

    In the framework of the SELENIUM project two full size flat fuel plates were produced with respectively Si and ZrN coated U(Mo) particles and irradiated in the BR2 reactor at SCK•CEN. Non-destructive analysis of the plates showed that the fuel swelling profiles of both SELENIUM plates were very similar to each other and none of the plates showed signs of pillowing or excessive swelling at the end of irradiation at the highest power position (local maximum 70% 235U). The microstructural analysis showed that the Si coated fuel has less interaction phase formation at low burn-up but at the highest burn-ups, defects start to develop on the IL-matrix interface. The ZrN coated fuel, shows a virtual absence of reaction between the U(Mo) and the Al, up to high fission densities after which the interaction layer formation starts and defects develop in the matrix near the U(Mo) particles. It was found and is confirmed by the SELENIUM (Surface Engineering of Low ENrIched Uranium-Molybdenum) experiment that there are two phenomena at play that need to be controlled: the formation of an interaction layer and swelling of the fuel. As the interaction layer formation occurs at the U(Mo)-matrix interface, applying a diffusion barrier (coating) at that interface should prevent the interaction between U(Mo) and the matrix. The U(Mo) swelling, observed to proceed at an accelerating rate with respect to fission density accumulation, is governed by linear solid state swelling and fission gas bubble swelling due to recrystallization of the fuel. The examination of the SELENIUM fuel plates clearly show that for the U(Mo) dispersion fuel to be qualified, the swelling rate at high burn-up needs to be reduced.

  10. Detection and analysis of particles with failed SiC in AGR-1 fuel compacts

    DOE PAGESBeta

    Hunn, John D.; Baldwin, Charles A.; Gerczak, Tyler J.; Montgomery, Fred C.; Morris, Robert N.; Silva, Chinthaka M.; Demkowicz, Paul A.; Harp, Jason M.; Ploger, Scott A.

    2016-04-06

    As the primary barrier to release of radioactive isotopes emitted from the fuel kernel, retention performance of the SiC layer in tristructural isotropic (TRISO) coated particles is critical to the overall safety of reactors that utilize this fuel design. Most isotopes are well-retained by intact SiC coatings, so pathways through this layer due to cracking, structural defects, or chemical attack can significantly contribute to radioisotope release. In the US TRISO fuel development effort, release of 134Cs and 137Cs are used to detect SiC failure during fuel compact irradiation and safety testing because the amount of cesium released by a compactmore » containing one particle with failed SiC is typically ten or more times higher than that released by compacts without failed SiC. Compacts with particles that released cesium during irradiation testing or post-irradiation safety testing at 1600–1800 °C were identified, and individual particles with abnormally low cesium retention were sorted out with the Oak Ridge National Laboratory (ORNL) Irradiated Microsphere Gamma Analyzer (IMGA). X-ray tomography was used for three-dimensional imaging of the internal coating structure to locate low-density pathways through the SiC layer and guide subsequent materialography by optical and scanning electron microscopy. In addition, all three cesium-releasing particles recovered from as-irradiated compacts showed a region where the inner pyrocarbon (IPyC) had cracked due to radiation-induced dimensional changes in the shrinking buffer and the exposed SiC had experienced concentrated attack by palladium; SiC failures observed in particles subjected to safety testing were related to either fabrication defects or showed extensive Pd corrosion through the SiC where it had been exposed by similar IPyC cracking.« less

  11. Silver (Ag) Transport Mechanisms in TRISO coated particles: A Critical Review

    SciTech Connect

    I J van Rooyen; J H Neethling; J A A Engelbrecht; P M van Rooyen; G Strydom

    2012-10-01

    Transport of 110mAg in the intact SiC layer of TRISO coated particles has been studied for approximately 30 years without arriving at a satisfactory explanation of the transport mechanism. In this paper the possible mechanisms postulated in previous experimental studies, both in-reactor and out-of reactor research environment studies are critically reviewed and of particular interest are relevance to very high temperature gas reactor operating and accident conditions. Among the factors thought to influence Ag transport are grain boundary stoichiometry, SiC grain size and shape, the presence of free silicon, nano-cracks, thermal decomposition, palladium attack, transmutation products, layer thinning and coated particle shape. Additionally new insight to nature and location of fission products has been gained via recent post irradiation electron microscopy examination of TRISO coated particles from the DOE’s fuel development program. The combined effect of critical review and new analyses indicates a direction for investigating possible the Ag transport mechanism including the confidence level with which these mechanisms may be experimentally verified.

  12. MINING PROCESS AND PRODUCT INFORMATION FROM PRESSURE FLUCTUATIONS WITHIN A FUEL PARTICLE COATER

    SciTech Connect

    Douglas W. Marshall; Charles M. Barnes

    2008-09-01

    The Next Generation Nuclear Power (NGNP) Fuel Development and Qualification Program included the design, installation, and testing of a 6-inch diameter nuclear fuel particle coater to demonstrate quality TRISO fuel production on a small industrial scale. Scale-up from the laboratory-scale coater faced challenges associated with an increase in the kernel charge mass, kernel diameter, and a redesign of the gas distributor to achieve adequate fluidization throughout the deposition of the four TRISO coating layers. TRISO coatings are applied at very high temperatures in atmospheres of dense particulate clouds, corrosive gases, and hydrogen concentrations over 45% by volume. The severe environment, stringent product and process requirements, and the fragility of partially-formed coatings limit the insertion of probes or instruments into the coater vessel during operation. Pressure instrumentation were installed on the gas inlet line and exhaust line of the 6-inch coater to monitor the bed differential pressure and internal pressure fluctuations emanating from the fuel bed as a result of bed and gas “bubble” movement. These instruments are external to the particle bed and provide a glimpse into the dynamics of fuel particle bed during the coating process and data that could be used to help ascertain the adequacy of fluidization and, potentially, the dominant fluidization regimes. Pressure fluctuation and differential pressure data are not presently useful as process control instruments, but data suggest a link between the pressure signal structure and some measurable product attributes that could be exploited to get an early estimate of the attribute values.

  13. Manufacturing and Properties of High-Velocity Oxygen Fuel (HVOF)-Sprayed FeVCrC Coatings

    NASA Astrophysics Data System (ADS)

    Sassatelli, Paolo; Bolelli, Giovanni; Lusvarghi, Luca; Manfredini, Tiziano; Rigon, Rinaldo

    2016-09-01

    This paper studies the microstructure, sliding wear behavior and corrosion resistance of high-velocity oxygen fuel (HVOF)-sprayed FeVCrC-based coatings. Various process parameters were tested to evaluate their effects on the coating properties, which were also compared to those of HVOF-sprayed NiCrBSi and Stellite-6 coatings. The Fe alloy coatings are composed of flattened splats, originating from molten droplets and consisting of a super-saturated solid solution, together with rounded particles, coming from partially unmolten material and containing V- and Fe-based carbide precipitates. All process parameters, apart from "extreme" settings with excess comburent in the flame, produce dense coatings, indicating that the feedstock powder is quite easily processable by HVOF. These coatings, with a microhardness of 650-750 HV0.3, exhibit wear rates of ≈2 × 10-6 mm3/(Nm) in ball-on-disk tests against sintered Al2O3 spheres. They perform far better than the reference coatings, and better than other Fe- and Ni-based alloy coatings tested in previous research. On the other hand, the corrosion resistance of the coating material (tested by electrochemical polarization in 0.1 M HCl solution) is quite low. Even in the absence of interconnected porosity, this results in extensive, selective damage to the Fe-based matrix. This coating material is therefore unadvisable for severely corrosive environments.

  14. Manufacturing and Properties of High-Velocity Oxygen Fuel (HVOF)-Sprayed FeVCrC Coatings

    NASA Astrophysics Data System (ADS)

    Sassatelli, Paolo; Bolelli, Giovanni; Lusvarghi, Luca; Manfredini, Tiziano; Rigon, Rinaldo

    2016-10-01

    This paper studies the microstructure, sliding wear behavior and corrosion resistance of high-velocity oxygen fuel (HVOF)-sprayed FeVCrC-based coatings. Various process parameters were tested to evaluate their effects on the coating properties, which were also compared to those of HVOF-sprayed NiCrBSi and Stellite-6 coatings. The Fe alloy coatings are composed of flattened splats, originating from molten droplets and consisting of a super-saturated solid solution, together with rounded particles, coming from partially unmolten material and containing V- and Fe-based carbide precipitates. All process parameters, apart from "extreme" settings with excess comburent in the flame, produce dense coatings, indicating that the feedstock powder is quite easily processable by HVOF. These coatings, with a microhardness of 650-750 HV0.3, exhibit wear rates of ≈2 × 10-6 mm3/(Nm) in ball-on-disk tests against sintered Al2O3 spheres. They perform far better than the reference coatings, and better than other Fe- and Ni-based alloy coatings tested in previous research. On the other hand, the corrosion resistance of the coating material (tested by electrochemical polarization in 0.1 M HCl solution) is quite low. Even in the absence of interconnected porosity, this results in extensive, selective damage to the Fe-based matrix. This coating material is therefore unadvisable for severely corrosive environments.

  15. Oleic acid coated magnetic nano-particles: Synthesis and characterizations

    SciTech Connect

    Panda, Biswajit Goyal, P. S.

    2015-06-24

    Magnetic nano particles of Fe{sub 3}O{sub 4} coated with oleic acid were synthesized using wet chemical route, which involved co-precipitation of Fe{sup 2+} and Fe{sup 3+} ions. The nano particles were characterized using XRD, TEM, FTIR, TGA and VSM. X-ray diffraction studies showed that nano particles consist of single phase Fe{sub 3}O{sub 4} having inverse spinel structure. The particle size obtained from width of Bragg peak is about 12.6 nm. TEM analysis showed that sizes of nano particles are in range of 6 to 17 nm with a dominant population at 12 - 14 nm. FTIR and TGA analysis showed that -COOH group of oleic acid is bound to the surface of Fe{sub 3}O{sub 4} particles and one has to heat the sample to 278° C to remove the attached molecule from the surface. Further it was seen that Fe{sub 3}O{sub 4} particles exhibit super paramagnetism with a magnetization of about 53 emu/ gm.

  16. Neutronic analysis stochastic distribution of fuel particles in Very High Temperature Gas-Cooled Reactors

    NASA Astrophysics Data System (ADS)

    Ji, Wei

    The Very High Temperature Gas-Cooled Reactor (VHTR) is a promising candidate for Generation IV designs due to its inherent safety, efficiency, and its proliferation-resistant and waste minimizing fuel cycle. A number of these advantages stem from its unique fuel design, consisting of a stochastic mixture of tiny (0.78mm diameter) microspheres with multiple coatings. However, the microsphere fuel regions represent point absorbers for resonance energy neutrons, resulting in the "double heterogeneity" for particle fuel. Special care must be taken to analyze this fuel in order to predict the spatial and spectral dependence of the neutron population in a steady-state reactor configuration. The challenges are considerable and resist brute force computation: there are over 1010 microspheres in a typical reactor configuration, with no hope of identifying individual microspheres in this stochastic mixture. Moreover, when individual microspheres "deplete" (e.g., burn the fissile isotope U-235 or transmute the fertile isotope U-238 (eventually) to Pu-239), the stochastic time-dependent nature of the depletion compounds the difficulty posed by the stochastic spatial mixture of the fuel, resulting in a prohibitive computational challenge. The goal of this research is to develop a methodology to analyze particle fuel randomly distributed in the reactor, accounting for the kernel absorptions as well as the stochastic depletion of the fuel mixture. This Ph.D. dissertation will address these challenges by developing a methodology for analyzing particle fuel that will be accurate enough to properly model stochastic particle fuel in both static and time-dependent configurations and yet be efficient enough to be used for routine analyses. This effort includes creation of a new physical model, development of a simulation algorithm, and application to real reactor configurations.

  17. Protection of porous carbon fuel particles from boudouard corrosion

    SciTech Connect

    Cooper, John F.

    2015-05-26

    A system for producing energy that includes infusing porous carbon particles produced by pyrolysis of carbon-containing materials with an off-eutectic salt composition thus producing pore-free carbon particles, and reacting the carbon particles with oxygen in a fuel cell according to the reaction C+O.sub.2=CO.sub.2 to produce electrical energy.

  18. Micromorphological characterization of zinc/silver particle composite coatings

    PubMed Central

    Méndez, Alia; Reyes, Yolanda; Trejo, Gabriel; StĘpień, Krzysztof

    2015-01-01

    ABSTRACT The aim of this study was to evaluate the three‐dimensional (3D) surface micromorphology of zinc/silver particles (Zn/AgPs) composite coatings with antibacterial activity prepared using an electrodeposition technique. These 3D nanostructures were investigated over square areas of 5 μm × 5 μm by atomic force microscopy (AFM), fractal, and wavelet analysis. The fractal analysis of 3D surface roughness revealed that (Zn/AgPs) composite coatings have fractal geometry. Triangulation method, based on the linear interpolation type, applied for AFM data was employed in order to characterise the surfaces topographically (in amplitude, spatial distribution and pattern of surface characteristics). The surface fractal dimension D f, as well as height values distribution have been determined for the 3D nanostructure surfaces. Microsc. Res. Tech. 78:1082–1089, 2015. © 2015 The Authors published by Wiley Periodicals, Inc. PMID:26500164

  19. Micromorphological characterization of zinc/silver particle composite coatings.

    PubMed

    Méndez, Alia; Reyes, Yolanda; Trejo, Gabriel; StĘpień, Krzysztof; Ţălu, Ştefan

    2015-12-01

    The aim of this study was to evaluate the three-dimensional (3D) surface micromorphology of zinc/silver particles (Zn/AgPs) composite coatings with antibacterial activity prepared using an electrodeposition technique. These 3D nanostructures were investigated over square areas of 5 μm × 5 μm by atomic force microscopy (AFM), fractal, and wavelet analysis. The fractal analysis of 3D surface roughness revealed that (Zn/AgPs) composite coatings have fractal geometry. Triangulation method, based on the linear interpolation type, applied for AFM data was employed in order to characterise the surfaces topographically (in amplitude, spatial distribution and pattern of surface characteristics). The surface fractal dimension Df , as well as height values distribution have been determined for the 3D nanostructure surfaces. PMID:26500164

  20. Critical Issues for Particle-Bed Reactor Fuels

    NASA Astrophysics Data System (ADS)

    Evans, Robert S.; Husser, Dewayne L.; Jensen, Russell R.; Kerr, John M.

    1994-07-01

    Particle-Bed Reactors (PBRs) potentially offer performance advantages for nuclear thermal propulsion, including very high power densities, thrust-to-weight ratios, and specific impulses. A key factor in achieving all of these is the development of a very-high-temperature fuel. The critical issues for all such PBR fuels are uranium loading, thermomechanical and thermochemical stability, compatibility with contacting materials, fission product retention, manufacturability, and operational tolerance for particle failures. Each issue is discussed with respect to its importance to PBR operation, its status among current fuels, and additional development needs. Mixed-carbide-based fuels are recommended for further development to support high-performance PBRs.

  1. Influences of Al particles on the microstructure and property of electrodeposited Ni-Al composite coatings

    NASA Astrophysics Data System (ADS)

    Cai, Fei; Jiang, Chuanhai

    2014-02-01

    Ni-Al composite coatings with different contents of Al microparticles were prepared from a conventional Watt bath. The influences of Al particle loadings in the bath on the surface morphology, composition, texture, grain size, microstrain, residual stress and anti-corrosion of the Ni-Al composite coating were investigated. The friction coefficients of the coatings at 200 °C were also evaluated by a pin-on-disctribometer. The results showed that the surface morphology of the coatings changed from pyramid + colonied structure to colonied structure with increasing Al particle loadings. The (2 0 0) preferred orientation for pure Ni coating evolved to random orientation with increasing Al particle loadings. The grain size obtained the minimum value of 72.28 nm at Al particle loading of 100 g/L and the microstrain of the coating increased with increasing the Al particle loadings. The incorporation of Al particles decreased the residual stress of the electro-deposited coating and all the coatings deposited at different Al particle loadings possessed low residual stress. As the Al particle loading increased, the anti-corrosion of the Ni-Al coatings increased owing to the combined effect of increasing Al content in the coatings and the texture evolution from (2 0 0) plane to (1 1 1) plane. The wear result suggested that the increasing Al particle content did not improve the wear performance of the Ni-Al composite coatings.

  2. Progress in Solving the Elusive Ag Transport Mechanism in TRISO Coated Particles: What is new?

    SciTech Connect

    Isabella Van Rooyen

    2014-10-01

    The TRISO particle for HTRs has been developed to an advanced state where the coating withstands internal gas pressures and retains fission products during irradiation and under postulated accidents. However, one exception is Ag that has been found to be released from high quality TRISO coated particles when irradiated and can also during high temperature accident heating tests. Although out- of- pile laboratory tests have never hither to been able to demonstrate a diffusion process of Ag in SiC, effective diffusion coefficients have been derived to successfully reproduce measured Ag-110m releases from irradiated HTR fuel elements, compacts and TRISO particles It was found that silver transport through SiC does not proceed via bulk volume diffusion. Presently grain boundary diffusion that may be irradiation enhanced either by neutron bombardment or by the presence of fission products such as Pd, are being investigated. Recent studies of irradiated AGR-1 TRISO fuel using scanning transmission electron microscopy (STEM), transmission kukuchi diffraction (TKD) patterns and high resolution transmission electron microscopy (HRTEM) have been used to further the understanding of Ag transport through TRISO particles. No silver was observed in SiC grains, but Ag was identified at triple-points and grain boundaries of the SiC layer in the TRISO particle. Cadmium was also found in some of the very same triple junctions, but this could be related to silver behavior as Ag-110m decays to Cd-110. Palladium was identified as the main constituent of micron-sized precipitates present at the SiC grain boundaries and in most SiC grain boundaries and the potential role of Pd in the transport of Ag will be discussed.

  3. Fuel Design for Particle-Bed Reactors for Thermal Propulsion Applications

    NASA Astrophysics Data System (ADS)

    Husser, Dewayne L.; Evans, Robert S.; Jensen, Russell R.; Kerr, John M.

    1994-07-01

    The design of particle bed reactor (PBR) fuels is an iterative process involving close coordination of design and manufacturing operations. The process starts with the generation of an initial particle design, based on a knowledge of the system requirements and interfaces (such as, fissile loading requirements, coolant type, exit gas temperatures, operation time, number of cycles, contacting materials, etc.). The designer must consider materials property data, heat-transfer and thermal-hydraulic characteristics of the particle and particle bed, and available (or anticipated) manufacturing technology. The design process also uses parametric studies to identify the influences of composition, size, and coating thickness on fuel performance. This resulting design is then used to provide a target manufacturing specification against which initial manufacturing development can be assessed and which provides the framework for manufacturing and testing derived feedback that can be incorporated into the subsequent particle design modifications. In this paper, an example of this design process for a hypothetical particle using a (U,Zr)C kernel and a NbC outer coating designed for a thermal propulsion application is given.

  4. Nuclear fuels status

    NASA Technical Reports Server (NTRS)

    Kania, Michael

    1991-01-01

    A discussion on coated particle fuel performance from a modular High Temperature Gas Reactor (HTGR) is presented along with experimental results. The following topics are covered: (1) the coated particle fuel concept; (2) the functional requirements; (3) performance limiting mechanisms; (4) fuel performance; and (5) methods/techniques for characterizing performance.

  5. Induction plasma calcining of pigment particles for thermal control coatings

    NASA Technical Reports Server (NTRS)

    Farley, E. P.

    1971-01-01

    Induction plasma heating techniques were studied for calcining zinc orthotitanate particles for use in thermal control coatings. Previous studies indicated that the optimum calcining temperature is between 1400 and 1750 C. An intermediate temperature (1670 C) was chosen as a reference point for running a temperature series at the reference point and 220 C on both sides. The effect of varying chamber temperature on the reflectance spectra, before and after vacuum UV irradiation, is presented. The correlation between Zn2Ti04 paramagnetic resonance activity and its susceptibility to vacuum UV damage is discussed.

  6. Pre- and post-irradiation characterization and properties measurements of ZrC coated surrogate TRISO particles

    SciTech Connect

    Vasudevamurthy, Gokul; Katoh, Yutai; Hunn, John D; Snead, Lance Lewis

    2010-09-01

    Zirconium carbide is a candidate to either replace or supplement silicon carbide as a coating material in TRISO fuel particles for high temperature gas-cooled reactor fuels. Six sets of ZrC coated surrogate microsphere samples, fabricated by the Japan Atomic Energy Agency using the fluidized bed chemical vapor deposition method, were irradiated in the High Flux Isotope Reactor at the Oak Ridge National Laboratory. These developmental samples available for the irradiation experiment were in conditions of either as-fabricated coated particles or particles that had been heat-treated to simulate the fuel compacting process. Five sets of samples were composed of nominally stoichiometric compositions, with the sixth being richer in carbon (C/Zr = 1.4). The samples were irradiated at 800 and 1250 C with fast neutron fluences of 2 and 6 dpa. Post-irradiation, the samples were retrieved from the irradiation capsules followed by microstructural examination performed at the Oak Ridge National Laboratory's Low Activation Materials Development and Analysis Laboratory. This work was supported by the US Department of Energy Office of Nuclear Energy's Advanced Gas Reactor program as part of International Nuclear Energy Research Initiative collaboration with Japan. This report includes progress from that INERI collaboration, as well as results of some follow-up examination of the irradiated specimens. Post-irradiation examination items included microstructural characterization, and nanoindentation hardness/modulus measurements. The examinations revealed grain size enhancement and softening as the primary effects of both heat-treatment and irradiation in stoichiometric ZrC with a non-layered, homogeneous grain structure, raising serious concerns on the mechanical suitability of these particular developmental coatings as a replacement for SiC in TRISO fuel. Samples with either free carbon or carbon-rich layers dispersed in the ZrC coatings experienced negligible grain size

  7. Analysis of particle behavior in High-Velocity Oxy-Fuel thermal spraying process

    NASA Astrophysics Data System (ADS)

    Katanoda, Hiroshi; Matsuo, Kazuyasu

    2003-08-01

    This paper analyzes the behavior of coating particle as well as the gas flow both of inside and outside the High-Velocity Oxy-Fuel (HVOF) thermal spraying gun by using quasi-one-dimensional analysis and numerical simulation. The HVOF gun in the present analysis is an axisymmetric convergent-divergent nozzle with the design Mach number of 2.0 followed by a straight passage called barrel. In the present analysis it is assumed that the influence of the particles injected in the gas flow is neglected, and the interaction between the particles is also neglected. The gas flow in the gun is assumed to be quasi-one-dimensional adiabatic flow. The velocity, temperature and density of gas in the jet discharged from the barrel exit are predicted by solving Navier-Stokes equations numerically. The particle equation of motion is numerically integrated using three-step Runge-Kutta method. The drag coefficient of the particle is calculated by linear interpolation of the experimental data obtained in the past. Particle mean temperature is calculated by using Ranz and Marchalls’ correlation for spherical particles. From the present analysis, the distributions of velocity and temperature of the coating particles flying inside and outside the HVOF gun are predicted.

  8. Method of producing carbon coated nano- and micron-scale particles

    DOEpatents

    Perry, W. Lee; Weigle, John C; Phillips, Jonathan

    2013-12-17

    A method of making carbon-coated nano- or micron-scale particles comprising entraining particles in an aerosol gas, providing a carbon-containing gas, providing a plasma gas, mixing the aerosol gas, the carbon-containing gas, and the plasma gas proximate a torch, bombarding the mixed gases with microwaves, and collecting resulting carbon-coated nano- or micron-scale particles.

  9. Heterogeneous nucleation as a potential sulphate-coating mechanism of atmospheric mineral dust particles and implications of coated dust on new particle formation

    NASA Astrophysics Data System (ADS)

    Korhonen, H.; Napari, I.; Timmreck, C.; VehkamäKi, H.; Pirjola, L.; Lehtinen, K. E. J.; Lauri, A.; Kulmala, M.

    2003-09-01

    The plausibility of heterogeneous conucleation of water, sulphuric acid, and ammonia as a pathway leading to soluble coating of atmospheric mineral dust is investigated. In addition, the effect of such sulphate-coated dust on the formation and growth of atmospheric aerosol particles is addressed. The simulated new particle formation mechanism is ternary nucleation of water, sulphuric acid, and ammonia vapors, while in the condensational growth process the effect of condensable organic vapor is also studied. The results indicate that soluble coating of dust by heterogeneous nucleation can occur at atmospheric sulphuric acid concentrations. In addition, the simulations show that homogeneous ternary nucleation and subsequent growth are decoupled. Although observed (or even higher) dust concentrations are unable to inhibit new particle formation, coated dust particles acting as condensation and coagulation sinks can prevent the growth of newly formed particles to detectable sizes. This is particularly true in desert areas, where organic vapor concentrations are low.

  10. Manufacture of bonded-particle nuclear fuel composites

    DOEpatents

    Stradley, J.G.; Sease, J.D.

    1973-10-01

    A preselected volume of nuclear fuel particles are placed in a cylindrical mold cavity followed by a solid pellet of resin--carbon matrix material of preselected volume. The mold is heated to liquefy the pellet and the liquefied matrix forced throughout the interstices of the fuel particles by advancing a piston into the mold cavity. Excess matrix is permitted to escape through a vent hole in the end of the mold opposite to that end where the pellet was originally disposed. After the matrix is resolidified by cooling, the resultant fuel composite is removed from the mold and the resin component of the matrix carbonized. (Official Gazette)

  11. Optical Anisotropy Measurements of TRISO Nuclear Fuel Particle Cross-Sections: The Method

    SciTech Connect

    Jellison Jr, Gerald Earle; Hunn, John D

    2008-01-01

    The analysis of two-modulator generalized ellipsometry microscope (2-MGEM) data to extract information on the optical anisotropy of coated particle fuel layers is discussed. Using a high resolution modification to the 2-MGEM, it is possible to obtain generalized ellipsometry images of coating layer cross-sections with a pixel size of 2.5 m and an optical resolution of ~ 4 m. The most important parameter that can be extracted from these ellipsometry images is the diattenuation, which can be directly related to the optical anisotropy factor (OAF or OPTAF) used in previous characterization studies of tristructural isotropic (TRISO) coated particles. Because high resolution images can be obtained, the data for each coating layer contains >6,000 points, allowing considerable statistical analysis. This analysis has revealed that the diattenuation of the inner pyrocarbon (IPyC) and outer pyrocarbon (OPyC) coatings varies significantly throughout the layer. The 2-MGEM data can also be used to determine the principal axis angle of the pyrocarbon layers, which is nearly perpendicular to the TRISO radius (i.e., growth direction) and corresponds to the average orientation of the graphine planes.

  12. Oxidation behaviour and electrical properties of cobalt/cerium oxide composite coatings for solid oxide fuel cell interconnects

    NASA Astrophysics Data System (ADS)

    Harthøj, Anders; Holt, Tobias; Møller, Per

    2015-05-01

    This work evaluates the performance of cobalt/cerium oxide (Co/CeO2) composite coatings and pure Co coatings to be used for solid oxide fuel cell (SOFC) interconnects. The coatings are electroplated on the ferritic stainless steels Crofer 22 APU and Crofer 22H. Coated and uncoated samples are exposed in air at 800 °C for 3000 h and oxidation rates are measured and oxide scale microstructures are investigated. Area-specific resistances (ASR) in air at 850 °C of coated and uncoated samples are also measured. A dual layered oxide scale formed on all coated samples. The outer layer consisted of Co, Mn, Fe and Cr oxide and the inner layer consisted of Cr oxide. The CeO2 was present as discrete particles in the outer oxide layer after exposure. The Cr oxide layer thicknesses and oxidations rates were significantly reduced for Co/CeO2 coated samples compared to for Co coated and uncoated samples. The ASR of all Crofer 22H samples increased significantly faster than of Crofer 22 APU samples which was likely due to the presence of SiO2 in the oxide/metal interface of Crofer 22H.

  13. Effect of Spray Particle Velocity on Cavitation Erosion Resistance Characteristics of HVOF and HVAF Processed 86WC-10Co4Cr Hydro Turbine Coatings

    NASA Astrophysics Data System (ADS)

    Kumar, R. K.; Kamaraj, M.; Seetharamu, S.; Pramod, T.; Sampathkumaran, P.

    2016-08-01

    The hydro plants utilizing silt-laden water for power generation suffer from severe metal wastage due to particle-induced erosion and cavitation. High-velocity oxy-fuel process (HVOF)-based coatings is widely applied to improve the erosion life. The process parameters such as particle velocity, size, powder feed rate, temperature, affect their mechanical properties. The high-velocity air fuel (HVAF) technology, with higher particle velocities and lower spray temperatures, gives dense and substantially nonoxidized coating. In the present study, the cavitation resistance of 86WC-10Co4Cr-type HVOF coating processed at 680 m/s spray particle velocity was compared with HVAF coatings made at 895, 960, and 1010 m/s. The properties such as porosity, hardness, indentation toughness, and cavitation resistance were investigated. The surface damage morphology has been analyzed in SEM. The cohesion between different layers has been examined qualitatively through scratch depth measurements across the cross section. The HVAF coatings have shown a lower porosity, higher hardness, and superior cavitation resistance. Delamination, extensive cracking of the matrix interface, and detachment of the WC grains were observed in HVOF coating. The rate of metal loss is low in HVAF coatings implying that process parameters play a vital role in achieving improved cavitation resistance.

  14. Mechanical behaviors of the dispersion nuclear fuel plates induced by fuel particle swelling and thermal effect II: Effects of variations of the fuel particle diameters

    NASA Astrophysics Data System (ADS)

    Ding, Shurong; Wang, Qiming; Huo, Yongzhong

    2010-02-01

    In order to predict the irradiation mechanical behaviors of plate-type dispersion nuclear fuel elements, the total burnup is divided into two stages: the initial stage and the increasing stage. At the initial stage, the thermal effects induced by the high temperature differences between the operation temperatures and the room temperature are mainly considered; and at the increasing stage, the intense mechanical interactions between the fuel particles and the matrix due to the irradiation swelling of fuel particles are focused on. The large-deformation thermo-elasto-plasticity finite element analysis is performed to evaluate the effects of particle diameters on the in-pile mechanical behaviors of fuel elements. The research results indicate that: (1) the maximum Mises stresses and equivalent plastic strains at the matrix increase with the fuel particle diameters; the effects of particle diameters on the maximum first principal stresses vary with burnup, and the considered case with the largest particle diameter holds the maximum values all along; (2) at the cladding near the interface between the fuel meat and the cladding, the Mises stresses and the first principal stresses undergo major changes with increasing burnup, and different variations exist for different particle diameter cases; (3) the maximum Mises stresses at the fuel particles rise with the particle diameters.

  15. Reactor Physics Parametric and Depletion Studies in Support of TRISO Particle Fuel Specification for the Next Generation Nuclear Plant

    SciTech Connect

    James W. Sterbentz; Bren Phillips; Robert L. Sant; Gray S. Chang; Paul D. Bayless

    2003-09-01

    Reactor physics calculations were initiated to answer several major questions related to the proposed TRISO-coated particle fuel that is to be used in the prismatic Very High Temperature Reactor (VHTR) or the Next Generation Nuclear Plant (NGNP). These preliminary design evaluation calculations help ensure that the upcoming fuel irradiation tests will test appropriate size and type of fuel particles for a future NGNP reactor design. Conclusions from these calculations are expected to confirm and suggest possible modifications to the current particle fuel parameters specified in the evolving Fuel Specification. Calculated results dispel the need for a binary fuel particle system, which is proposed in the General Atomics GT-MHR concept. The GT-MHR binary system is composed of both a fissile and fertile particle with 350- and 500- micron kernel diameters, respectively. For the NGNP reactor, a single fissile particle system (single UCO kernel size) can meet the reactivity and power cycle length requirements demanded of the NGNP. At the same time, it will provide substantial programmatic cost savings by eliminating the need for dual particle fabrication process lines and dual fuel particle irradiation tests required of a binary system. Use of a larger 425-micron kernel diameter single fissile particle (proposed here), as opposed to the 350-micron GT-MHR fissile particle size, helps alleviate current compact particle packing fractions fabrication limitations (<35%), improves fuel block loading for higher n-batch reload options, and tracks the historical correlation between particle size and enrichment (10 and 14 wt% U-235 particle enrichments are proposed for the NGNP). Overall, the use of the slightly larger kernel significantly broadens the NGNP reactor core design envelope and provides increased design margin to accommodate the (as yet) unknown final NGNP reactor design. Maximum power-peaking factors are calculated for both the initial and equilibrium NGNP cores

  16. Performance of HTGR biso- and triso-coated fertile particles irradiated in capsule HT-34

    SciTech Connect

    Long, E.L. Jr.; Tiegs, T.N.; Robbins, J.M.; Kania, M.J.

    1981-08-01

    Experiment HT-34, irradiated in the target region of the High Flux Isotope Reactor (HFIR), was designed to correlate HTGR Biso- and Triso-coated particle performance with fabrication parameters. Gamma analysis of the irradiated Triso-coated ThO/sub 2/ particles showed that the SiC deposited at the highest coating rate apparently had the best cesium-retention properties. Results of a similar analysis of the irradiated Biso-coated ThO/sub 2/ particles showed no differences in performance that could be related to coating conditions, but all the particles showed a significant loss of cesium (> 50%) at the higher temperatures. Pressure-vessel failures occurred with a significant number of particles; however, fission-gas-content measurements made at room temperature showed that the intact Biso particles from all batches except one became permeable during irradiation.

  17. Engineered plant biomass particles coated with biological agents

    DOEpatents

    Dooley, James H.; Lanning, David N.

    2014-06-24

    Plant biomass particles coated with a biological agent such as a bacterium or seed, characterized by a length dimension (L) aligned substantially parallel to a grain direction and defining a substantially uniform distance along the grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) normal to W and L. In particular, the L.times.H dimensions define a pair of substantially parallel side surfaces characterized by substantially intact longitudinally arrayed fibers, the W.times.H dimensions define a pair of substantially parallel end surfaces characterized by crosscut fibers and end checking between fibers, and the L.times.W dimensions define a pair of substantially parallel top and bottom surfaces.

  18. Engineered plant biomass particles coated with bioactive agents

    DOEpatents

    Dooley, James H; Lanning, David N

    2013-07-30

    Plant biomass particles coated with a bioactive agent such as a fertilizer or pesticide, characterized by a length dimension (L) aligned substantially parallel to a grain direction and defining a substantially uniform distance along the grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) normal to W and L. In particular, the L.times.H dimensions define a pair of substantially parallel side surfaces characterized by substantially intact longitudinally arrayed fibers, the W.times.H dimensions define a pair of substantially parallel end surfaces characterized by crosscut fibers and end checking between fibers, and the L.times.W dimensions define a pair of substantially parallel top and bottom surfaces.

  19. Description of particle induced damage on protected silver coatings.

    PubMed

    Schwinde, Stefan; Schürmann, Mark; Jobst, Paul Johannes; Kaiser, Norbert; Tünnermann, Andreas

    2015-06-01

    In the visible to infrared spectral range, highly-reflective silver mirrors are applied in the manufacture of optical instruments such as telescopes. However, it is still difficult to combine high reflectivity and long-term stability of the protected silver coating. We show that the deposition of impervious protective layers is necessary but often not sufficient for long-term environmental stability. Hygroscopic air borne particles absorbed by the protections surface attract water molecules and form a solution. This solution first damages the protection, subsequently permeates the protection and finally damages the silver whereby the reflectivity is reduced. We demonstrate this particular damage mechanism with different experiments and describe this mechanism in detail. PMID:26192652

  20. Anisotropy measurement of pyrolytic carbon layers of coated particles

    SciTech Connect

    Vesyolkin, Ju. A. Ivanov, A. S.; Trushkina, T. V.

    2015-12-15

    Equipment at the National Research Center Kurchatov Institute intended for the anisotropy determination of pyrolytic carbon layers in coated particles (CPs) of the GT-MGR reactor is tested and calibrated. The dependence of the anisotropy coefficient on the size of the measurement region is investigated. The results of measuring the optical anisotropy factor (OPTAF) for an aluminum mirror, rutile crystal, and available CP samples with the known characteristics measured previously using ORNL equipment (United States) are presented. In addition, measurements of CP samples prepared at VNIINM are performed. A strong dependence of the data on the preparation quality of metallographic sections is found. Our investigations allow us to make the conclusion on the working capacity of the existing equipment for measuring the anisotropy of pyrolytic carbon CP coatings using the equipment at the Kurchatov Institute with the relative error of about 1%. It is shown that the elimination of the errors caused by the stochastic fluctuations in a measuring path by mathematical processing of the signal allows us to decrease the relative error of OPTAF measurements to ∼0.3%.

  1. A Theoretical Study on Gas-Phase Coating of Aerosol Particles

    PubMed

    Jain; Fotou; Kodas

    1997-01-01

    In situ coating of aerosol particles by gas-phase and surface reaction in a flow reactor is modeled accounting for scavenging (capture of small particles by large particles) and simultaneous surface reaction along with the finite sintering rate of the scavenged particles. A log-normal size distribution is assumed for the host and coating particles to describe coagulation and a monodisperse size distribution is used for the coating particles to describe sintering. As an example, coating of titania particles with silica in a continuous flow hot-wall reactor was modeled. High temperatures, low reactant concentrations, and large host particle surface areas favored smoother coatings in the parameter range: temperature 1700-1800 K, host particle number concentration 1 x 10(5)-1 x 10(7) #/cm3, average host particle size 1 &mgr;m, inlet coating reactant concentration (SiCl4) 2 x 10(-7)-2 x 10(-10) mol/cm3, and various surface reaction rates. The fraction of silica deposited on the TiO2 particles decreased by more than seven times with a hundredfold increase in SiCl4 inlet concentration because of the resulted increase in the average SiO2 particle size under the assumed coating conditions. Increasing the TiO2 particle number concentration resulted in higher scavenging efficiency of SiO2. In the TiO2/SiO2 system it is likely that surface reaction as well as scavenging play important roles in the coating process. The results agree qualitatively with experimental observations of TiO2 particles coated in situ with silica.

  2. Development of an advanced bond coat for solid oxide fuel cell interconnector applications

    NASA Astrophysics Data System (ADS)

    Yeh, An-Chou; Chen, Yu-Ming; Liu, Chien-Kuo; Shong, Wei-Ja

    2015-11-01

    An advanced bond coat has been developed for solid oxide fuel cell interconnector applications; a low thermal expansion superalloy has been selected as the substrate, and the newly developed bond coat is applied between the substrate and the LSM top coat. The bond coat composition is designed to be near thermodynamic equilibrium with the substrate to minimize interdiffusion with the substrate while providing oxidation protection for the substrate. The bond coat exhibits good oxidation resistance, a low area specific resistance, and a low thermal expansion coefficient at 800 °C; experimental results indicate that interdiffusion between the bond coat and the substrate can be hindered.

  3. Modeling emissivity of low-emissivity coating containing horizontally oriented metallic flake particles

    NASA Astrophysics Data System (ADS)

    Chen, Shuai; Yuan, Le; Weng, Xiaolong; Deng, Longjiang

    2014-11-01

    The scattering and absorption cross sections of horizontally oriented metallic flake particles are estimated by extended geometric optics that includes diffraction and edge effects. Emissivity of the coating containing those particles is calculated using Kubelka-Munk theory. The dependence of emissivity of the coating on the radius, thickness, content of metallic flake particles and coating thickness is discussed. Finally, theoretical results are compared with the experimental measurements with Al/acrylic resin coating system and the results show that simulation values are in good agreement with experimental ones.

  4. Underwater Coatings Testing for INEEL Fuel Basin Applications

    SciTech Connect

    Julia L. Tripp

    2004-01-01

    The Idaho National Engineering and Environmental Laboratory (INEEL) is deactivating several fuel storage basins. Airborne contamination is a concern when the sides of the basins are exposed and allowed to dry during water removal. One way of controlling this airborne contamination is to fix the contamination in place while the pool walls are still submerged. There are many underwater coatings available on the market that are used in marine, naval and other applications. A series of tests were run to determine whether the candidate underwater fixatives are easily applied and adhere well to the substrates (pool wall materials) found in INEEL fuel pools. The four pools considered included (1) Test Area North (TAN-607) with epoxy painted concrete walls; (2) Idaho Nuclear Technology and Engineering Center (INTEC) (CPP-603) with bare concrete walls; (3) Materials Test Reactor (MTR) Canal with stainless steel lined concrete walls; and (4) Power Burst Facility (PBF-620) with stainless steel lined concrete walls on the bottom and epoxy painted carbon steel lined walls on the upper portions. Therefore, the four materials chosen for testing included bare concrete, epoxy painted concrete, epoxy painted carbon steel, and stainless steel. The typical water temperature of the pools varies from 55 F to 80 F dependent on the pool and the season. These tests were done at room temperature.

  5. Protective/conductive coatings for ferritic stainless steel interconnects used in solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Shaigan, Nima

    Ferritic stainless steels are the most commonly used materials for solid oxide fuel cell interconnect application. Although these alloys may meet the criteria for interconnect application for short periods of service, their application is limited for long-term use (i.e., 40,000 h) due to poor oxidation behaviour that results in a rapid increase in contact resistance. In addition, volatile Cr species migrating from the chromia scale can poison the cathode resulting in a considerable drop in performance of the cell. Coatings and surface modifications have been developed in order to mitigate the abovementioned problems. In this study, composite electrodeposition of reactive element containing particles in a metal matrix was considered as a solution to the interconnect problems. Nickel and Co were used as the metal matrix and LaCrO3 particles as the reactive element containing particles. The role of the particles was to improve the oxidation resistance and oxide scale adhesion, while the role of Ni or Co was to provide a matrix for embedding of the particles. Also, oxidation of the Ni or Co matrix led to the formation of conductive oxides. Moreover, as another part of this study, the effect of substrate composition on performance of steel interconnects was investigated. Numerous experimental techniques were used to study and characterise the oxidation behaviour of the composite coatings, as well as the metal-oxide scale interface properties. Scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX), as well as surface analysis techniques including Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS), were used for the purpose of characterization. The substrate used for coating was AISI-SAE 430 stainless steel that is considered as a typical, formerly used interconnect material. Also, for the purpose of the metal-oxide scale interfacial study, ZMG232 stainless steel that is a specially

  6. Ceria coated Ni as anodes for direct utilization of methane in low-temperature solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Xia, Changrong; Fan, Jue; Peng, Ranran; Meng, Guangyao

    A new type of anode, a Ni framework coated with Sm-doped ceria (SDC), was developed for direct utilization of methane fuel in low-temperature solid oxide fuel cells (SOFCs) with thin-film SDC electrolytes. The coated SDC was prepared with an ion impregnating method and the electrolyte films were fabricated with a co-pressing and co-firing technique. The impregnating process produced an ideal anode microstructure where nickel particles were effectively connected and uniformly covered with nanosized SDC. This anode microstructure was believed to enlarge the triple-phase boundaries and therefore enhance the anode performance. The cell performance was much higher than that of a conventional fuel cell with a Ni-SDC composite anode. In addition, the performance increased with impregnated SDC loading up to a maximum at 20 mg cm -2, indicating that the coated SDC is the contributing factor for the enhanced fuel cell performance. Power density as high as 571 and 353 mW cm -2 were obtained at 600 °C when humidified hydrogen and methane were used as fuels, respectively. The stability of the cell also increased with the SDC loading. No significant degradation was observed for anodes coated with 20 and 25 mg cm -2 SDC. This verifies that the coated SDC electrodes are very effective in suppressing catalytic carbon formation by blocking methane from approaching the Ni, which is catalytically active towards methane pyrolysis. The high performance of this anode shows high promise in the developing field of direct hydrocarbon SOFCs.

  7. Tribological behavior of near-frictionless carbon coatings in high- and low-sulfur diesel fuels.

    SciTech Connect

    Alzoubi, M. F.; Ajayi, O. O.; Eryilmaz, O. L.; Ozturk, O.; Erdemir, A.; Fenske, G.

    2000-01-19

    The sulfur content in diesel fuel has a significant effect on diesel engine emissions, which are currently subject to environmental regulations. It has been observed that engine particulate and gaseous emissions are directly proportional to fuel sulfur content. With the introduction of low-sulfur fuels, significant reductions in emissions are expected. The process of sulfur reduction in petroleum-based diesel fuels also reduces the lubricity of the fuel, resulting in premature failure of fuel injectors. Thus, another means of preventing injector failures is needed for engines operating with low-sulfur diesel fuels. In this study, the authors evaluated a near-frictionless carbon (NFC) coating (developed at Argonne National Laboratory) as a possible solution to the problems associated with fuel injector failures in low-lubricity fuels. Tribological tests were conducted with NFC-coated and uncoated H13 and 52100 steels lubricated with high- and low- sulfur diesel fuels in a high-frequency reciprocating test machine. The test results showed that the NFC coatings reduced wear rates by a factor of 10 over those of uncoated steel surfaces. In low-sulfur diesel fuel, the reduction in wear rate was even greater (i.e., by a factor of 12 compared to that of uncoated test pairs), indicating that the NFC coating holds promise as a potential solution to wear problems associated with the use of low-lubricity diesel fuels.

  8. Encapsulation of TRISO particle fuel in durable soda-lime-silicate glasses

    NASA Astrophysics Data System (ADS)

    Heath, Paul G.; Corkhill, Claire L.; Stennett, Martin C.; Hand, Russell J.; Meyer, Willem C. H. M.; Hyatt, Neil C.

    2013-05-01

    Tri-Structural Isotropic (TRISO) coated particle-fuel is a key component in designs for future high temperature nuclear reactors. This study investigated the suitability of three soda lime silicate glass compositions, for the encapsulation of simulant TRISO particle fuel. A cold press and sinter (CPS) methodology was employed to produce TRISO particle-glass composites. Composites produced were determined to have an aqueous durability, fracture toughness and Vickers' hardness comparable to glasses currently employed for the disposal of high level nuclear wastes. Sintering at 700 °C for 30 min was found to remove all interconnected porosity from the composite bodies and oxidation of the outer pyrolytic carbon layer during sintering was prevented by processing under a 5% H2/N2 atmosphere. However, the outer pyrolytic carbon layer was not effectively wetted by the encapsulating glass matrix. The aqueous durability of the TRISO particle-glass composites was investigated using PCT and MCC-1 tests combined with geochemical modelling. It was found that durability was dependent on silicate and calcium solution saturation. This study provides significant advancements in the preparation of TRISO particle encapsulant waste forms. The potential for the use of non-borosilicate sintered glass composites for TRISO particle encapsulation has been confirmed, although further refinements are required.

  9. Testing of sludge coating adhesiveness on fuel elements in 105-K west basin

    SciTech Connect

    Maassen, D.P., Fluor Daniel Hanford

    1997-03-11

    This report summarizes the results from the first sludge adherence tests performed in the 105-K West Basin on N Reactor fuel. The outside surface of the outer fuel elements were brushed, using stainless steel wire brushes, to test the adhesiveness of various types of sludge coatings to the cladding`s surface. The majority of the sludge was removed by the wire brushes in this test but different types of sludge were more adhesive than others. Particularly, an orange rust-like sludge coating that was just slightly more adherent to the fuel`s cladding than the majority of the sludge coatings and a thick white vertical strip sludge coating that was much more difficult to remove. The test demonstrated that all of the sludge could be removed from the outer fuel elements` surfaces if the need arises.

  10. Resuspension of coarse fuel hot particles in the Chernobyl area.

    PubMed

    Wagenpfeil, F; Tschiersch, J

    2001-01-01

    Measurements of resuspended aerosol in the Chernobyl 30-km exclusion zone have shown coarse fuel hot particles in the activity range 1-12 Bq 137Cs per particle. The particles were sampled with newly designed rotating arm impactors which simultaneously collect during the same experiment three samples with fuel particles in the size ranges larger than 3 microns, larger than 6 microns and larger than 9 microns in geometric diameter. The radionuclide ratios, determined after gamma-spectrometry, were in good agreement with the theoretical calculations for the radionuclide-composition of the Chernobyl Nuclear Power Plant at the moment of the accident and the measured hot particles in soil in the early years after the accident. The number concentrations of airborne hot particles were derived from digital autoradiography. For wind resuspension, maximal concentrations of 2.6 coarse hot particles per 1000 m3 and during agricultural activities 36 coarse hot particles per 1000 m3 were measured. The geometric diameter of single hot particles was estimated to be between 6 and 12 microns.

  11. Interaction of fission products and SiC in TRISO fuel particles: a limiting HTGR design parameter

    SciTech Connect

    Stansfield, O.M.; Homan, F.J.; Simon, W.A.; Turner, R.F.

    1983-09-01

    The fuel particle system for the steam cycle cogeneration HTGR being developed in the US consists of 20% enriched UC/sub 0/./sub 3/O/sub 1/./sub 7/ and ThO/sub 2/ kernels with TRISO coatings. The reaction of fission products with the SiC coating is the limiting thermochemical coating failure mechanism affecting performance. The attack of the SiC by palladium (Pd) is considered the controlling reaction with systems of either oxide or carbide fuels. The lanthanides, such as cerium, neodymium, and praseodymium, also attack SiC in carbide fuel particles. In reactor design, the time-temperature relationships at local points in the core are used to calculate the depth of SiC-Pd reaction. The depth of penetration into the SiC during service varies with core power density, power distribution, outlet gas temperature, and fuel residence time. These parameters are adjusted in specifying the core design to avoid SiC coating failure.

  12. Microstructure and Properties of Porous Abradable Alumina Coatings Flame-Sprayed with Semi-molten Particles

    NASA Astrophysics Data System (ADS)

    Li, Chang-Jiu; Zou, Jiao; Huo, Hui-Bin; Yao, Jian-Tao; Yang, Guan-Jun

    2016-01-01

    High-efficiency gas turbines require high-temperature sealing by use of abradable porous ceramic coatings to increase engine efficiency. In this study, porous Al2O3 coatings were deposited by flame spraying; the coatings were applied in a semi-molten state by controlled melting of the sprayed powder particles. The effects of the degree of melting of the sprayed particles, which depends on spraying conditions, on coating microstructure and porosity were investigated. The degree of melting of the sprayed particles was characterized by use of 3D confocal laser microscopy. The porosity of the coating was estimated by image analysis. The results showed that the degree of melting of alumina particles can be changed from 70 to 30%, and thus coating porosity can be increased from 30% up to over 70%. The standard hardness test yielded no useful data for porous coatings deposited by use of sprayed particles with a degree of melting <60%, and a hardness of 32-75 HR15Y for Al2O3 coatings deposited by use of sprayed particles with a degree of melting >60%. Pin-on-disk abrasion tests, performed at room temperature by use of an Inconel 738 (IN738) nickel-based superalloy pin with a spherical tip 5 mm in diameter, were conducted on the porous alumina coating to evaluate its abrasion behavior. It was found that for coatings of hardness <32 HR15Y and porosity >40% the wear weight loss of the IN738 pin was negligible despite the high rate of wear of the coating. It is evident that flame-sprayed porous alumina coatings of high porosity prepared by this approach have potential for use as abradable coatings for gas turbines operating at high temperatures.

  13. Mechanical behaviors of the dispersion nuclear fuel plates induced by fuel particle swelling and thermal effect I: Effects of variations of the fuel particle volume fractions

    NASA Astrophysics Data System (ADS)

    Wang, Qiming; Yan, Xiaoqing; Ding, Shurong; Huo, Yongzhong

    2010-05-01

    A new method of modeling the in-pile mechanical behaviors of dispersion nuclear fuel elements is proposed. Considering the irradiation swelling together with the thermal effect, numerical simulations of the in-pile mechanical behaviors are performed with the developed finite element models for different fuel particle volume fractions of the fuel meat. The effects of the particle volume fractions on the mechanical performances of the fuel element are studied. The research results indicate that: (1) the maximum Mises stresses and equivalent plastic strains at the matrix increase with the particle volume fractions at each burnup; the locations of the maximum first principal stresses shift with increasing burnup; at low burnups, the maximum first principal stresses increase with the particle volume fractions; while at high burnups, the 20% volume fraction case holds the lowest value; (2) at the cladding, the maximum equivalent plastic strains and the tensile principal stresses increase with the particle volume fractions; while the maximum Mises stresses do not follow this order at high burnups; (3) the maximum Mises stresses at the fuel particles increase with the particle volume fractions, and the particles will engender plastic strains until the particle volume fraction reaches high enough.

  14. Electron microscopic evaluation and fission product identification of irradiated TRISO coated particles from the AGR-1 experiment: A preliminary Study

    SciTech Connect

    I J van Rooyen; D E Janney; B D Miller; J L Riesterer; P A Demkowicz

    2012-10-01

    ABSTRACT Post-irradiation examination of coated particle fuel from the AGR-1 experiment is in progress at Idaho National Laboratory and Oak Ridge National Laboratory. In this presentation a brief summary of results from characterization of microstructures in the coating layers of selected irradiated fuel particles with burnup of 11.3% and 19.3% FIMA will be given. The main objective of the characterization were to study irradiation effects, fuel kernel porosity, layer debonding, layer degradation or corrosion, fission-product precipitation, grain sizes, and transport of fission products from the kernels across the TRISO layers. Characterization techniques such as scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, and wavelength dispersive spectroscopy were used. A new approach to microscopic quantification of fission-product precipitates is also briefly demonstrated. The characterization emphasized fission-product precipitates in the SiC-IPyC interface, SiC layer and the fuel-buffer interlayer, and provided significant new insights into mechanisms of fission-product transport. Although Pd-rich precipitates were identified at the SiC-IPyC interlayer, no significant SiC-layer thinning was observed for the particles investigated. Characterization of these precipitates highlighted the difficulty of measuring low concentration Ag in precipitates with significantly higher concentrations of contain Pd and U. Different approaches to resolving this problem are discussed. Possible microstructural differences between particles with high and low releases of Ag particles are also briefly discussed, and an initial hypothesis is provided to explain fission-product precipitate compositions and locations. No SiC phase transformations or debonding of the SiC-IPyC interlayer as a result of irradiation were observed. Lessons learned from the post-irradiation examination are described and future actions are recommended.

  15. Bioactive glass coatings with hydroxyapatite and Bioglass (registered) particles on Ti-based implants. 1. Processing

    SciTech Connect

    Gomez-Vega, J.M.; Saiz, E.; Tomsia, A.P.; Marshall, G.W.; Marshall, S.J.

    1999-06-01

    Silicate-based glasses with thermal expansion coefficients that match those of Ti6Al4V were prepared and used to coat Ti6Al4V by a simple enameling technique. Bioglass (BG) (registered) or hydroxyapatite (HA) particles were embedded on the coatings in order to enhance their bioactivity. HA particles were partially embedded during heating and remained firmly embedded on the coating after cooling. There was no apparent reaction at the glass/HA interface at the temperatures used in this work (800-840 degrees C). In contrast, BG particles softened and some infiltration into the glass coating took place during heat treatment. In this case, particles with sizes over 45 (mu)m were required, otherwise the particles became hollow due to the infiltration and crystallization of the glass surface. The concentration of the particles on the coating was limited to 20% of surface coverage. Concentrations above this value resulted in cracked coatings due to excessive induced stress. Cracks did not prop agate along the interfaces when coatings were subjected to Vickers indentation tests, indicating that the particle/glass and glass/metal interfaces exhibited strong bonds. Enameling, producing excellent glass/metal adhesion with well-attached bioactive particles on the surface, is a promising method of forming reliable and lasting implants which can endure substantial chemical and mechanical stresses.

  16. Bioactive glass coatings with hydroxyapatite and Bioglass particles on Ti-based implants. 1. Processing.

    PubMed

    Gomez-Vega, J M; Saiz, E; Tomsia, A P; Marshall, G W; Marshall, S J

    2000-01-01

    Silicate-based glasses with thermal expansion coefficients that match those of Ti6A14V were prepared and used to coat Ti6A14V by a simple enameling technique. Bioglass (BG) or hydroxyapatite (HA) particles were embedded on the coatings in order to enhance their bioactivity. HA particles were immersed partially during heating and remained firmly embedded on the coating after cooling. There was no apparent reaction at the glass/HA interface at the temperatures used in this work (800-840 degrees C). In contrast, BG particles softened and some infiltration into the glass coating took place during heat treatment. In this case, particles with sizes over 45 microm were required, otherwise the particles became hollow due to the infiltration and crystallization of the glass surface. The concentration of the particles on the coating was limited to 20% of surface coverage. Concentrations above this value resulted in cracked coatings due to excessive induced stress. Cracks did not propagate along the interfaces when coatings were subjected to Vickers indentation tests, indicating that the particle/glass and glass/metal interfaces exhibited strong bonds. Enameling, producing excellent glass/metal adhesion with well-attached bioactive particles on the surface, is a promising method of forming reliable and lasting implants which can endure substantial chemical and mechanical stresses.

  17. Reactive Atmospheric Plasma Spraying of AlN Coatings: Influence of Aluminum Feedstock Particle Size

    NASA Astrophysics Data System (ADS)

    Shahien, Mohammed; Yamada, Motohiro; Yasui, Toshiaki; Fukumoto, Masahiro

    2011-03-01

    Feedstock powder characteristics (size distribution, morphology, shape, specific mass, and injection rate) are considered to be one of the key factors in controlling plasma-sprayed coatings microstructure and properties. The influence of feedstock powder characteristics to control the reaction and coatings microstructure in reactive plasma spraying process (RPS) is still unclear. This study, investigated the influence of feedstock particle size in RPS of aluminum nitride (AlN) coatings, through plasma nitriding of aluminum (Al) feedstock powders. It was possible to fabricate AlN-based coatings through plasma nitriding of all kinds of Al powders in atmospheric plasma spray (APS) process. The nitriding ratio was improved with decreasing the particle size of feedstock powder, due to improving the nitriding reaction during flight. However, decreasing the particle size of feedstock powder suppressed the coatings thickness. Due to the loss of the powder during the injection, the excessive vaporization of fine Al particles and the completing nitriding reaction of some fine Al particles during flight. The feedstock particle size directly affects on the nitriding, melting, flowability, and the vaporization behaviors of Al powders during spraying. It concluded that using smaller particle size powders is useful for improving the nitriding ratio and not suitable for fabrication thick AlN coatings in reactive plasma spray process. To fabricate thick AlN coatings through RPS, enhancing the nitriding reaction of Al powders with large particle size during spraying is required.

  18. Effect of soluble polymer binder on particle distribution in a drying particulate coating.

    PubMed

    Buss, Felix; Roberts, Christine C; Crawford, Kathleen S; Peters, Katharina; Francis, Lorraine F

    2011-07-01

    Soluble polymer is frequently added to inorganic particle suspensions to provide mechanical strength and adhesiveness to particulate coatings. To engineer coating microstructure, it is essential to understand how drying conditions and dispersion composition influence particle and polymer distribution in a drying coating. Here, a 1D model revealing the transient concentration profiles of particles and soluble polymer in a drying suspension is proposed. Sedimentation, evaporation and diffusion govern particle movement with the presence of soluble polymer influencing the evaporation rate and solution viscosity. Results are summarized in drying regime maps that predict particle accumulation at the free surface or near the substrate as conditions vary. Calculations and experiments based on a model system of poly(vinyl alcohol) (PVA), silica particles and water reveal that the addition of PVA slows the sedimentation and diffusion of the particles during drying such that accumulation of particles at the free surface is more likely.

  19. Ceramic plasma-sprayed coating of melting crucibles for casting metal fuel slugs

    NASA Astrophysics Data System (ADS)

    Kim, Ki Hwan; Lee, Chong Tak; Lee, Chan Bock; Fielding, R. S.; Kennedy, J. R.

    2013-10-01

    Thermal cycling and melt reaction studies of ceramic coatings plasma-sprayed on Nb substrates were carried out to evaluate the performance of barrier coatings for metallic fuel casting applications. Thermal cycling tests of the ceramic plasma-sprayed coatings to 1450 °C showed that HfN, TiC, ZrC, and Y2O3 coating had good cycling characteristics with few interconnected cracks even after 20 cycles. Interaction studies by 1550 °C melt dipping tests of the plasma-sprayed coatings also indicated that HfN and Y2O3 do not form significant reaction layer between U-20 wt.% Zr melt and the coating layer. Plasma-sprayed Y2O3 coating exhibited the most promising characteristics among HfN, TiC, ZrC, and Y2O3 coating.

  20. Ceramic plasma-sprayed coating of melting crucibles for casting metal fuel slugs

    SciTech Connect

    K.H. Kim; C.T. Lee; C.B. Lee; R.S. Fielding; J.R. Kennedy

    2013-10-01

    Thermal cycling and melt reaction studies of ceramic coatings plasma-sprayed on Nb substrates were carried out to evaluate the performance of barrier coatings for metallic fuel casting applications. Thermal cycling tests of the ceramic plasma-sprayed coatings to 1450 degrees C showed that HfN, TiC, ZrC, and Y2O3 coating had good cycling characteristics with few interconnected cracks even after 20 cycles. Interaction studies by 1550 degrees C melt dipping tests of the plasma-sprayed coatings also indicated that HfN and Y2O3 do not form significant reaction layer between U–20 wt.% Zr melt and the coating layer. Plasma-sprayed Y2O3 coating exhibited the most promising characteristics among HfN, TiC, ZrC, and Y2O3 coating.

  1. Electroless Ni-Cu-P/nano-graphite composite coatings for bipolar plates of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Lee, Cheng-Kuo

    2012-12-01

    This study evaluates the effects of an electroless Ni-Cu-P/nano-graphite composite coating on the surface characteristics of anodized 5083 aluminum alloy, including electrical resistivity, corrosion resistance of the alloy in a simulated solution of 0.5 M H2SO4 + 2 ppm NaF in polymer electrolyte membrane fuel cells (PEMFCs). The co-deposition and adhesion of the composite coatings on a 5083 substrate are enhanced by an anodizing process. The electroless Ni-Cu-P plating solution is prepared by adding different CuSO4·5H2O concentrations into the electroless Ni-P plating solution and adding nano-graphite (15-40 nm) particles to form the Ni-Cu-P/nano-graphite composite coatings. Experimental results indicate that the electroless Ni-Cu-P/nano-graphite composite coating enhances the hardness, conductivity, corrosion resistance of the 5083 substrate in the corrosive solution. The anodizing treatment enhances the electroless composite coatings by providing better uniformity, density, and adhesion compared to substrate without anodizing treatment. The electroless Ni-Cu-P/nano-graphite composite coating deposited on the optimal anodized 5083 substrate at a low CuSO4·5H2O concentration of 0.25 g l-1 with 20 g l-1 nano-graphite added have the best surface structure, highest hardness, electrical conductivity and corrosion resistance. Therefore, this novel electroless Ni-Cu-P/nano-graphite composite-coated 5083 aluminum alloy has potential applications in bipolar plates of PEM fuel cells.

  2. One-step electrophoretic deposition for the preparation of superhydrophobic silica particle/trimethylsiloxysilicate composite coatings.

    PubMed

    Ogihara, Hitoshi; Katayama, Takafumi; Saji, Tetsuo

    2011-10-15

    SiO(2) particle/silicone resin (trimethylsiloxysilicate (TMSS)) composite coatings were prepared by electrophoretic deposition (EPD), and their wettability was examined. SiO(2) coatings prepared by EPD baths without TMSS were hydrophilic, while superhydrophobicity was observed for SiO(2)/TMSS composite coatings. IR spectra and EDS analyses revealed that not only SiO(2) particles but also TMSS electrophoretically moved toward a cathode; as a result, hydrophilic SiO(2) particles turned into superhydrophobic composite coatings by one-step EPD. SEM and AFM images of the superhydrophobic SiO(2)/TMSS composite coatings showed the presence of both nanometer- and micrometer-sized roughness in their surfaces. Particle size of SiO(2) had a great influence on the wettability of the composite coatings. The superhydrophobic SiO(2)/TMSS composite coatings showed excellent water repellency; they repelled running water continuously. In addition, by controlling the amount of deposited SiO(2) particles and TMSS, transparent superhydrophobic SiO(2)/TMSS composite coatings were prepared.

  3. Enhancement of oxidation resistance via a self-healing boron carbide coating on diamond particles.

    PubMed

    Sun, Youhong; Meng, Qingnan; Qian, Ming; Liu, Baochang; Gao, Ke; Ma, Yinlong; Wen, Mao; Zheng, Weitao

    2016-02-02

    A boron carbide coating was applied to diamond particles by heating the particles in a powder mixture consisting of H3BO3, B and Mg. The composition, bond state and coverage fraction of the boron carbide coating on the diamond particles were investigated. The boron carbide coating prefers to grow on the diamond (100) surface than on the diamond (111) surface. A stoichiometric B4C coating completely covered the diamond particle after maintaining the raw mixture at 1200 °C for 2 h. The contribution of the boron carbide coating to the oxidation resistance enhancement of the diamond particles was investigated. During annealing of the coated diamond in air, the priory formed B2O3, which exhibits a self-healing property, as an oxygen barrier layer, which protected the diamond from oxidation. The formation temperature of B2O3 is dependent on the amorphous boron carbide content. The coating on the diamond provided effective protection of the diamond against oxidation by heating in air at 1000 °C for 1 h. Furthermore, the presence of the boron carbide coating also contributed to the maintenance of the static compressive strength during the annealing of diamond in air.

  4. Enhancement of oxidation resistance via a self-healing boron carbide coating on diamond particles

    PubMed Central

    Sun, Youhong; Meng, Qingnan; Qian, Ming; Liu, Baochang; Gao, Ke; Ma, Yinlong; Wen, Mao; Zheng, Weitao

    2016-01-01

    A boron carbide coating was applied to diamond particles by heating the particles in a powder mixture consisting of H3BO3, B and Mg. The composition, bond state and coverage fraction of the boron carbide coating on the diamond particles were investigated. The boron carbide coating prefers to grow on the diamond (100) surface than on the diamond (111) surface. A stoichiometric B4C coating completely covered the diamond particle after maintaining the raw mixture at 1200 °C for 2 h. The contribution of the boron carbide coating to the oxidation resistance enhancement of the diamond particles was investigated. During annealing of the coated diamond in air, the priory formed B2O3, which exhibits a self-healing property, as an oxygen barrier layer, which protected the diamond from oxidation. The formation temperature of B2O3 is dependent on the amorphous boron carbide content. The coating on the diamond provided effective protection of the diamond against oxidation by heating in air at 1000 °C for 1 h. Furthermore, the presence of the boron carbide coating also contributed to the maintenance of the static compressive strength during the annealing of diamond in air. PMID:26831205

  5. Enhancement of oxidation resistance via a self-healing boron carbide coating on diamond particles

    NASA Astrophysics Data System (ADS)

    Sun, Youhong; Meng, Qingnan; Qian, Ming; Liu, Baochang; Gao, Ke; Ma, Yinlong; Wen, Mao; Zheng, Weitao

    2016-02-01

    A boron carbide coating was applied to diamond particles by heating the particles in a powder mixture consisting of H3BO3, B and Mg. The composition, bond state and coverage fraction of the boron carbide coating on the diamond particles were investigated. The boron carbide coating prefers to grow on the diamond (100) surface than on the diamond (111) surface. A stoichiometric B4C coating completely covered the diamond particle after maintaining the raw mixture at 1200 °C for 2 h. The contribution of the boron carbide coating to the oxidation resistance enhancement of the diamond particles was investigated. During annealing of the coated diamond in air, the priory formed B2O3, which exhibits a self-healing property, as an oxygen barrier layer, which protected the diamond from oxidation. The formation temperature of B2O3 is dependent on the amorphous boron carbide content. The coating on the diamond provided effective protection of the diamond against oxidation by heating in air at 1000 °C for 1 h. Furthermore, the presence of the boron carbide coating also contributed to the maintenance of the static compressive strength during the annealing of diamond in air.

  6. Enhancement of oxidation resistance via a self-healing boron carbide coating on diamond particles.

    PubMed

    Sun, Youhong; Meng, Qingnan; Qian, Ming; Liu, Baochang; Gao, Ke; Ma, Yinlong; Wen, Mao; Zheng, Weitao

    2016-01-01

    A boron carbide coating was applied to diamond particles by heating the particles in a powder mixture consisting of H3BO3, B and Mg. The composition, bond state and coverage fraction of the boron carbide coating on the diamond particles were investigated. The boron carbide coating prefers to grow on the diamond (100) surface than on the diamond (111) surface. A stoichiometric B4C coating completely covered the diamond particle after maintaining the raw mixture at 1200 °C for 2 h. The contribution of the boron carbide coating to the oxidation resistance enhancement of the diamond particles was investigated. During annealing of the coated diamond in air, the priory formed B2O3, which exhibits a self-healing property, as an oxygen barrier layer, which protected the diamond from oxidation. The formation temperature of B2O3 is dependent on the amorphous boron carbide content. The coating on the diamond provided effective protection of the diamond against oxidation by heating in air at 1000 °C for 1 h. Furthermore, the presence of the boron carbide coating also contributed to the maintenance of the static compressive strength during the annealing of diamond in air. PMID:26831205

  7. Ice formation on nitric acid coated dust particles: Laboratory and modeling studies

    SciTech Connect

    Kulkarni, Gourihar R.; Zhang, Kai; Zhao, Chun; Nandasiri, Manjula I.; Shutthanandan, V.; Liu, Xiaohong; Fast, Jerome D.; Berg, Larry K.

    2015-08-16

    Changes in the ice nucleation characteristics of atmospherically relevant mineral dust particles due to nitric acid coating are not well understood. Further, the atmospheric implications of dust coating on ice-cloud properties under different assumptions of primary ice nucleation mechanisms are unknown. We investigated ice nucleation ability of Arizona test dust, illite, K-feldspar and quartz as a function of temperature (-25 to -30°C) and relative humidity with respect to water (75 to 110%). Particles were size selected at 250 nm and transported (bare or coated) to the ice nucleation chamber to determine the fraction of particles nucleating ice at various temperature and water saturation conditions. All dust nucleated ice at water-subsaturated conditions, but the coated particles showed a reduction in their ice nucleation ability compared to bare particles. However, at water-supersaturated conditions, we observed that bare and coated particles had nearly similar ice nucleation characteristics. X-ray diffraction patterns indicated that structural properties of bare dust particles modified after acid treatment. We found that lattice parameters were slightly different, but crystallite sizes of the coated particles were reduced compared to bare particles. Next, single-column model results show that simulated ice crystal number concentrations mostly depends upon fraction of particles that are coated, primary ice nucleation mechanisms, and the competition between ice nucleation mechanisms to nucleate ice. In general, we observed that coating modify the ice-cloud properties and the picture of ice and mixed-phase cloud evolution is complex when different primary ice nucleation mechanisms are competing for fixed water vapor mass.

  8. Kaolinite particles as ice nuclei: learning from the use of different kaolinite samples and different coatings

    NASA Astrophysics Data System (ADS)

    Wex, H.; DeMott, P. J.; Tobo, Y.; Hartmann, S.; Rösch, M.; Clauss, T.; Tomsche, L.; Niedermeier, D.; Stratmann, F.

    2014-06-01

    Kaolinite particles from two different sources (Fluka and Clay Minerals Society (CMS)) were examined with respect to their ability to act as ice nuclei (IN). This was done in the water-subsaturated regime where often deposition ice nucleation is assumed to occur, and for water-supersaturated conditions, i.e., in the immersion freezing mode. Measurements were done using a flow tube (the Leipzig Aerosol Cloud Interaction Simulator, LACIS) and a continuous-flow diffusion chamber (CFDC). Pure and coated particles were used, with coating thicknesses of a few nanometers or less, where the coating consisted of levoglucosan, succinic acid or sulfuric acid. In general, it was found that the coatings strongly reduced deposition ice nucleation. Remaining ice formation in the water-subsaturated regime could be attributed to immersion freezing, with particles immersed in concentrated solutions formed by the coatings. In the immersion freezing mode, ice nucleation rate coefficients jhet from both instruments agreed well with each other, particularly when the residence times in the instruments were accounted for. Fluka kaolinite particles coated with either levoglucosan or succinic acid showed the same IN activity as pure Fluka kaolinite particles; i.e., it can be assumed that these two types of coating did not alter the ice-active surface chemically, and that the coatings were diluted enough in the droplets that were formed prior to the ice nucleation, so that freezing point depression was negligible. However, Fluka kaolinite particles, which were either coated with pure sulfuric acid or were first coated with the acid and then exposed to additional water vapor, both showed a reduced ability to nucleate ice compared to the pure particles. For the CMS kaolinite particles, the ability to nucleate ice in the immersion freezing mode was similar for all examined particles, i.e., for the pure ones and the ones with the different types of coating. Moreover, jhet derived for the CMS

  9. Coating-type three-dimensional acetate-driven microbial fuel cells.

    PubMed

    Yu, Jin; Tang, Yulan

    2015-08-01

    This study uses sodium acetate as fuel to construct bioelectricity in coating-type three-dimensional microbial fuel cells anode. The coating-type three-dimensional anode was constructed using iron net as structural support, adhering a layer of carbon felt as primary coating and using carbon powder and 30% PTFE solution mixture as coating. The efficiency of electricity production and wastewater treatment were analyzed for the three-dimensional acetate-fed (C2H3NaO2) microbial fuel cells with the various ratio of the coating mixture. The results showed that the efficiency of electricity production was significantly improved when using the homemade coating-type microbial fuel cells anode compared with the one without coating on the iron net, which the apparent internal resistance was decreased by 59.4% and the maximum power density was increased by 1.5 times. It was found the electricity production was greatly influenced by the ratio of the carbon powder and PTFE in the coating. The electricity production was the highest with apparent internal resistance of 190 Ω, and maximum power density of 5189.4 mW m(-3) when 750 mg of carbon powder and 10 ml of PTFE (i.e., ratio 75:1) was used in the coating. With the efficiency of electricity production, wide distribution and low cost of the raw materials, the homemade acetate-fed microbial fuel cells provides a valuable reference to the development of the composition microbial fuel cell anode production.

  10. Ice Nucleation and Droplet Formation by Bare and Coated Black Carbon Particles

    SciTech Connect

    Friedman, Beth J.; Kulkarni, Gourihar R.; Beranek, Josef; Zelenyuk, Alla; Thornton, Joel A.; Cziczo, Daniel J.

    2011-10-13

    We have studied the ice formation at heterogeneous and homogeneous temperatures, as well as droplet activation and hygroscopicity of soot particles of variable size and composition. Coatings of adipic, malic, and oleic acid were applied to span a relevant range of solubility, and both uncoated and oleic acid coated soot particles were exposed to ozone to simulate atmospheric oxidation. The results are interpreted in terms of onset ice nucleation with a comparison to a well characterized mineral dust particle that acts as an efficient ice nucleus, as well as particle hygroscopicity. At 253K and 243K, we found no evidence of heterogeneous ice nucleation occurring above the level of detection for our experimental conditions. Above water saturation, droplet formation was observed. At 233K, we observe the occurrence of homogeneous ice nucleation for all particles studied. Coatings also did not significantly alter the ice nucleation behavior of soot particles, but aided in the uptake of water. Hygroscopicity studies confirmed that pure soot particles were hydrophobic, and coated soot particles activated as droplets at high water supersaturations. A small amount of heterogeneous ice nucleation either below the detection limit of our instrument or concurrent with droplet formation and/or homogeneous freezing cannot be precluded, but we are able to set limits for its frequency. We conclude from our studies that both uncoated and coated soot particles are unlikely to contribute to the global budget of heterogeneous ice nuclei at temperatures between 233K and 253K.

  11. Ice Nucleation and Droplet Formation by Bare and Coated Soot Particles

    SciTech Connect

    Friedman, Beth J.; Kulkarni, Gourihar R.; Beranek, Josef; Zelenyuk, Alla; Thornton, Joel A.; Cziczo, Daniel J.

    2011-09-13

    We have studied ice formation at temperatures relevant to homogeneous and heterogeneous ice nucleation, as well as droplet activation and hygroscopicity, of soot particles of variable size and composition. Coatings of adipic, malic, and oleic acid were applied to span an atmospherically relevant range of solubility, and both uncoated and oleic acid coated soot particles were exposed to ozone to simulate atmospheric oxidation. The results are interpreted in terms of onset ice nucleation, with a comparison to a mineral dust particle that acts as an efficient ice nucleus, and particle hygroscopicity. At 253K and 243K, we found no evidence of heterogeneous ice nucleation occurring above the level of detection for our experimental conditions. Above water saturation, only droplet formation was observed. At 233K, we observe the occurrence of homogeneous ice nucleation for all particles studied. Coatings also did not significantly alter the ice nucleation behavior of soot particles, but aided in the uptake of water. Hygroscopicity studies confirmed that pure soot particles were hydrophobic, and coated soot particles activated as droplets at high water supersaturations. A small amount of heterogeneous ice nucleation either below the detection limit of our instrument or concurrent with droplet formation and/or homogeneous freezing cannot be precluded, but we are able to set limits for its frequency. We conclude that both uncoated and coated soot particles representative of those generated in our studies are unlikely to significantly contribute to the global budget of heterogeneous ice nuclei at temperatures between 233K and 253K.

  12. Identification of Silver and Palladium in Irradiated TRISO Coated Particles of the AGR-1 Experiment

    SciTech Connect

    van Rooyen, Y. J.; Lillo, T. M.; Wu, Y. Q.

    2014-03-01

    Evidence of the release of certain metallic fission product through intact tristructural isotropic (TRISO) particles has been seen for decades around the world, as well as in the recent AGR-1 experiment at Idaho National Laboratory (INL). However, understanding the basic mechanism of transport is still lacking. This understanding is important because the TRISO coating is part of the high temperature gas reactor functional containment and critical for the safety strategy for licensing purposes. Our approach to identify fission products in irradiated AGR-1 TRISO fuel using scanning transmission electron microscopy (STEM), Electron Energy Loss Spectroscopy (EELS) and Energy Filtered TEM (EFTEM), has led to first-of-a-kind data at the nano-scale indicating the presence of silver at triple points and grain boundaries of the SiC layer in the TRISO particle. Cadmium was also found in the triple junctions. In this initial study, the silver was only identified in SiC grain boundaries and triple points on the edge of the SiC-IPyC interface up to a depth of approximately 0.5 um. Palladium was identified as the main constituent of micron-sized precipitates present at the SiC grain boundaries. Additionally spherical nano-sized palladium rich precipitates were found inside the SiC grains. These nano-sized Pd precipitates were distributed up to a depth of 5 um away from the SiC-IPyC interlayer. No silver was found in the center of the micron-sized fission product precipitates using these techniques, although silver was found on the outer edge of one of the Pd-U-Si containing precipitates which was facing the IPyC layer. Only Pd-U containing precipitates were identified in the IPyC layer and no silver was identified in the IPyC layer. The identification of silver alongside the grain boundaries and the findings of Pd alongside grain boundaries as well as inside the grains, provide significant knowledge for understanding silver and palladium transport in TIRSO fuel, which has been

  13. Comparison of the Mechanical and Electrochemical Properties of WC-25Co Coatings Obtained by High Velocity Oxy-Fuel and Cold Gas Spraying

    NASA Astrophysics Data System (ADS)

    Couto, M.; Dosta, S.; Fernández, J.; Guilemany, J. M.

    2014-12-01

    Cold gas spray (CGS) coatings were previously produced by spraying WC-25Co cermet powders onto Al7075-T6 and low-carbon steel substrates. Unlike conventional flame spray techniques (e.g., high-velocity oxy-fuel; HVOF), no melting of the powder occurs; the particles are deformed and bond together after being sprayed by a supersonic jet of compressed gas, thereby building up several layers and forming a coating. WC-Co cermets are used in wear-resistant parts, because of their combination of mechanical, physical, and chemical properties. XRD tests were previously run on the initial powder and the coatings to determine possible phase changes during spraying. The bonding strength of the coatings was measured by adhesion tests. Here, WC-25Co coatings were also deposited on the same substrates by HVOF spraying. The wear resistance and fracture toughness of the coatings obtained previously by CGS and the HVOF coatings obtained here were studied. Their corrosion resistance was determined by electrochemical measurements. It was possible to achieve thick, dense, and hard CGS coatings on Al7075-T6 and low-carbon steel substrates, with better or the same mechanical and electrochemical properties as those of the HVOF coatings; making the former a highly competitive method for producing WC-25Co coatings.

  14. One-step electrodeposition of self-assembled colloidal particles: a novel strategy for biomedical coating.

    PubMed

    Sun, Jiadi; Liu, Xiaoya; Meng, Long; Wei, Wei; Zheng, Yufeng

    2014-09-23

    A novel biomedical coating was prepared from self-assembled colloidal particles through direct electrodeposition. The particles, which are photo-cross-linkable and nanoscaled with a high specific surface area, were obtained via self-assembly of amphiphilic poly(γ-glutamic acid)-g-7-amino-4-methylcoumarin (γ-PGA-g-AMC). The size, morphology, and surface charge of the resulting colloidal particles and their dependence on pH, initial concentrations, and UV irradiation were successfully studied. A nanostructured coating was formed in situ on the surface of magnesium alloys by electrodeposition of colloidal particles. The composition, morphology, and phase of the coating were monitored using Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and X-ray diffraction. The corrosion test showed that the formation of the nanostructured coating on magnesium alloys effectively improved their initial anticorrosion properties. More importantly, the corrosion resistance was further enhanced by chemical photo-cross-linking. In addition, the low cytotoxicity of the coated samples was confirmed by MTT assay against NIH-3T3 normal cells. The contribution of our work lies in the creation of a novel strategy to fabricate a biomedical coating in view of the versatility of self-assembled colloidal particles and the controllability of the electrodeposition process. It is believed that our work provides new ideas and reliable data to design novel functional biomedical coatings.

  15. Electroless plating preparation and electromagnetic properties of Co-coated carbonyl iron particles/polyimide composite

    NASA Astrophysics Data System (ADS)

    Zhou, Yingying; Zhou, Wancheng; Li, Rong; Qing, Yuchang; Luo, Fa; Zhu, Dongmei

    2016-03-01

    To solve the serious electromagnetic interference problems at elevated temperature, one thin microwave-absorbing sheet employing Co-coated carbonyl iron particles and polyimide was prepared. The Co-coated carbonyl iron particles were successfully prepared using an electroless plating method. The microstructure, composition, phase and static magnetic properties of Co-coated carbonyl iron particles were characterized by combination of scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The electromagnetic parameters of Co-coated carbonyl iron particles/polyimide composite were measured in the frequency range of 2-18 GHz, and the electromagnetic loss mechanism of the material-obtained was discussed. The microwave absorption properties of composites before and after heat treatment at 300 °C for 100 h were characterized in 2-18 GHz frequency range. It was established that composites based on Co-coated carbonyl iron demonstrate thermomagnetic stability, indicating that Co coating reduces the oxidation of carbonyl iron. Thus, Co-coated carbonyl iron particles/polyimide composites are useful in the design of microwave absorbers operating at temperatures up to 300 °C.

  16. Scattering of Gaussian Beam by a Conducting Spheroidal Particle with Confocal Dielectric Coating

    NASA Astrophysics Data System (ADS)

    Sun, Xianming; Wang, Haihua; Zhang, Huayong

    2010-09-01

    An analytic solution to the scattering by a coated spheroidal particle, for arbitrary incidence of a Gaussian beam, is constructed by expanding the incident and scattered electromagnetic fields in terms of spheroidal vector wave functions. The unknown expansion coefficients are determined by a system of linear equations derived from the appropriate boundary conditions. Numerical results of the normalized differential scattering cross section of the conducting and coated spheroidal particle are evaluated, and the scattering characteristics are discussed concisely.

  17. Electron Microscopic Evaluation and Fission Product Identification of Irradiated TRISO Coated Particles from the AGR-1 Experiment: A Preliminary Review

    SciTech Connect

    IJ van Rooyen; DE Janney; BD Miller; PA DEmkowicz; J Riesterer

    2014-05-01

    Post-irradiation examination of coated particle fuel from the AGR-1 experiment is in progress at Idaho National Laboratory and Oak Ridge National Laboratory. In this paper a brief summary of results from characterization of microstructures in the coating layers of selected irradiated fuel particles with burnup of 11.3% and 19.3% FIMA will be given. The main objectives of the characterization were to study irradiation effects, fuel kernel porosity, layer debonding, layer degradation or corrosion, fission-product precipitation, grain sizes, and transport of fission products from the kernels across the TRISO layers. Characterization techniques such as scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, and wavelength dispersive spectroscopy were used. A new approach to microscopic quantification of fission-product precipitates is also briefly demonstrated. Microstructural characterization focused on fission-product precipitates in the SiC-IPyC interface, the SiC layer and the fuel-buffer interlayer. The results provide significant new insights into mechanisms of fission-product transport. Although Pd-rich precipitates were identified at the SiC-IPyC interlayer, no significant SiC-layer thinning was observed for the particles investigated. Characterization of these precipitates highlighted the difficulty of measuring low concentrations of Ag in precipitates with significantly higher concentrations of Pd and U. Different approaches to resolving this problem are discussed. An initial hypothesis is provided to explain fission-product precipitate compositions and locations. No SiC phase transformations were observed and no debonding of the SiC-IPyC interlayer as a result of irradiation was observed for the samples investigated. Lessons learned from the post-irradiation examination are described and future actions are recommended.

  18. Metal organic chemical vapor deposition of environmental barrier coatings for the inhibition of solid deposit formation from heated jet fuel

    NASA Astrophysics Data System (ADS)

    Mohan, Arun Ram

    Solid deposit formation from jet fuel compromises the fuel handling system of an aviation turbine engine and increases the maintenance downtime of an aircraft. The deposit formation process depends upon the composition of the fuel, the nature of metal surfaces that come in contact with the heated fuel and the operating conditions of the engine. The objective of the study is to investigate the effect of substrate surfaces on the amount and nature of solid deposits in the intermediate regime where both autoxidation and pyrolysis play an important role in deposit formation. A particular focus has been directed to examining the effectiveness of barrier coatings produced by metal organic chemical vapor deposition (MOCVD) on metal surfaces for inhibiting the solid deposit formation from jet fuel degradation. In the first part of the experimental study, a commercial Jet-A sample was stressed in a flow reactor on seven different metal surfaces: AISI316, AISI 321, AISI 304, AISI 347, Inconel 600, Inconel 718, Inconel 750X and FecrAlloy. Examination of deposits by thermal and microscopic analysis shows that the solid deposit formation is influenced by the interaction of organosulfur compounds and autoxidation products with the metal surfaces. The nature of metal sulfides was predicted by Fe-Ni-S ternary phase diagram. Thermal stressing on uncoated surfaces produced coke deposits with varying degree of structural order. They are hydrogen-rich and structurally disordered deposits, spherulitic deposits, small carbon particles with relatively ordered structures and large platelets of ordered carbon structures formed by metal catalysis. In the second part of the study, environmental barrier coatings were deposited on tube surfaces to inhibit solid deposit formation from the heated fuel. A new CVD system was configured by the proper choice of components for mass flow, pressure and temperature control in the reactor. A bubbler was designed to deliver the precursor into the reactor

  19. Fission-product behaviour in irradiated TRISO-coated particles: Results of the HFR-EU1bis experiment and their interpretation

    NASA Astrophysics Data System (ADS)

    Barrachin, M.; Dubourg, R.; de Groot, S.; Kissane, M. P.; Bakker, K.

    2011-08-01

    It is important to understand fission-product (FP) and kernel micro-structure evolution in TRISO-coated fuel particles. FP behaviour, while central to severe-accident evaluation, impacts: evolution of the kernel oxygen potential governing in turn carbon oxidation (amoeba effect and pressurization); particle pressurization through fission-gas release from the kernel; and coating mechanical resistance via reaction with some FPs (Pd, Cs, Sr). The HFR-Eu1bis experiment irradiated five HTR fuel pebbles containing TRISO-coated UO 2 particles and went beyond current HTR specifications (e.g., central temperature of 1523 K). This study presents ceramographic and EPMA examinations of irradiated urania kernels and coatings. Significant evolutions of the kernel (grain structure, porosity, metallic-inclusion size, intergranular bubbles) as a function of temperature are shown. Results concerning FP migration are presented, e.g., significant xenon, caesium and palladium release from the kernel, molybdenum and ruthenium mainly present in metallic precipitates. The observed FP and micro-structural evolutions are interpreted and explanations proposed. The effect of high flux rate and high temperature on fission-gas behaviour, grain-size evolution and kernel swelling is discussed. Furthermore, Cs, Mo and Zr behaviour is interpreted in connection with oxygen-potential. This paper shows that combining state-of-the-art post-irradiation examination and state-of-the-art modelling fundamentally improves understanding of HTR fuel behaviour.

  20. Effects of volatile coatings on the morphology and optical detection of combustion-generated black carbon particles.

    SciTech Connect

    Bambha, Ray.; Dansson, Mark A; Schrader, Paul E.; Michelsen, Hope A.

    2013-09-01

    We have measured time-resolved laser-induced incandescence (LII) from combustion-generated mature soot extracted from a burner and (1) coated with oleic acid or (2) coated with oleic acid and then thermally denuded using a thermodenuder. The soot samples were size selected using a differential mobility analyser and characterized with a scanning mobility particle sizer, centrifugal particle mass analyser, and transmission electron microscope. The results demonstrate a strong influence of coatings particle morphology and on the magnitude and temporal evolution of the LII signal. For coated particles higher laser fluences are required to reach LII signal levels comparable to those of uncoated particles. This effect is predominantly attributable to the additional energy needed to vaporize the coating while heating the particle. LII signals are higher and signal decay rates are significantly slower for thermally denuded particles relative to coated or uncoated particles, particularly at low and intermediate laser fluences.

  1. Characterization of Vc-Vb Particles Reinforced Fe-Based Composite Coatings Produced by Laser Cladding

    NASA Astrophysics Data System (ADS)

    Qu, K. L.; Wang, X. H.; Wang, Z. K.

    2016-03-01

    In situ synthesized VC-VB particles reinforced Fe-based composite coatings were produced by laser beam melting mixture of ferrovanadium (Fe-V) alloy, boron carbide (B4C), CaF2 and Fe-based self-melting powders. The results showed that VB particles with black regular and irregular blocky shape and VC with black flower-like shape were uniformly distributed in the coatings. The type, amount, and size of the reinforcements were influenced by the content of FeV40 and B4C powders. Compared to the substrate, the hardness and wear resistance of the composite coatings were greatly improved.

  2. Suspension High Velocity Oxy-Fuel (SHVOF)-Sprayed Alumina Coatings: Microstructure, Nanoindentation and Wear

    NASA Astrophysics Data System (ADS)

    Murray, J. W.; Ang, A. S. M.; Pala, Z.; Shaw, E. C.; Hussain, T.

    2016-10-01

    Suspension high velocity oxy-fuel spraying can be used to produce thermally sprayed coatings from powdered feedstocks too small to be processed by mechanical feeders, allowing formation of nanostructured coatings with improved density and mechanical properties. Here, alumina coatings were produced from submicron-sized feedstock in aqueous suspension, using two flame combustion parameters yielding contrasting microstructures. Both coatings were tested in dry sliding wear conditions with an alumina counterbody. The coating processed with high combustion power of 101 kW contained 74 wt.% amorphous phase and 26 wt.% crystalline phase (95 wt.% gamma and 3 wt.% alpha alumina), while the 72-kW coating contained lower 58 wt.% amorphous phase and 42 wt.% crystalline phases (73 wt.% was alpha and 26 wt.% gamma). The 101-kW coating had a dry sliding specific wear rate between 4 and 4.5 × 10-5 mm3/Nm, 2 orders of magnitude higher than the 72-kW coating wear rate of 2-4.2 × 10-7 mm3/Nm. A severe wear regime dominated by brittle fracture and grain pullout of the coating was responsible for the wear of the 101-kW coating, explained by mean fracture toughness three times lower than the 72-kW coating, owing to the almost complete absence of alpha alumina.

  3. Understanding Particle Defect Transport in an Ultra-Clean Sputter Coating Process

    SciTech Connect

    Walton, C; Kearney, P; Folta, J; Sweeney, D; Mirkarimi, P

    2003-03-24

    Low-defect mask blanks remain a key technical challenge to Extreme Ultraviolet Lithography (EUVL). The mask blank is ion-beam sputter-coated with an 81-layer Mo/Si multilayer stack for high reflectance at {lambda} = 13.4nm. The current mask coating process can achieve a median added defect level of 0.05 defects/cm{sup 2} (12 added defects 90nm or larger on a 200mm Si-wafer test substrate), but this must be reduced by about a factor of 10 to meet mask cost requirements for EUVL. To further reduce the particle defect level, we have studied pathways for particle transport, using test particles and particles native to the coating process, and combined the results into a computational model of particle transport in an ion-beam sputter system. At process pressure, gas drag is negligible for particles above 100nm, so particles travel ballistically until they hit a surface. Bounce from chamber walls allows particles to reach all surfaces in the chamber if they have initial velocities above {approx}100m/s. The ion beam has sufficient momentum to entrain slower particles and accelerate them toward the sputter target, where some can bounce to the substrate. The model shows preliminary agreement with experimental defect distributions on witness wafers at various positions within the coating chamber.

  4. Water uptake by sodium chloride particles coated with insoluble organics: impact of chain length

    NASA Astrophysics Data System (ADS)

    Robinson, C. B.; Zarzana, K. J.; Hasenkopf, C. A.; Tolbert, M. A.

    2011-12-01

    Light extinction by particles is strongly dependent on chemical composition, particle size, and water uptake. Relative humidity affects extinction by causing changes in refractive index and particle size due to hygroscopic growth. The ability of particles to take up water depends on its composition and structure. Organic compounds and inorganic salts are often found to be internally mixed within the same aerosol particle. There is currently a great deal of interest in aqueous particles with an insoluble organic coating. The impact of organic films on particle water uptake is uncertain. Therefore, a systematic study that examines water uptake as a function of the chemical nature, packing structure, and coating thickness is highly desirable. These data are critical to evaluate the aerosol direct effect on climate, which is the most uncertain aspect of future climate change. To determine how tightly packed the organic component is, a range organic compounds with different chain lengths, such as decanoic (C10), myristic (C14), stearic (C18), and docosanoic (C22) acids, were used. Coated aerosols are generated and sized using a TSI constant output atomizer and scanning mobility particle sizer. A cavity ring-down aerosol extinction spectrometer at 532 nm is used to measure the optical growth factor as a function of relative humidity for the internally mixed particles. We explored the relationship between optical growth and packing structure by varying the organic component chain length and working with different coating thicknesses.

  5. Dielectric coating of iron particles by electrostatic colloidal deposition

    NASA Astrophysics Data System (ADS)

    Kim, Daniel

    Iron is a soft magnetic material widely used in electric motors, generators, and transformers because they demand high permeability and low core loss. The main goal of this project is to develop a commercially viable coating of iron powders for press-and-sinter processing that would enable higher firing temperatures to anneal out magnetic defects, while maintaining high electrical resistivity (˜10,000 muO-cm) and high iron density (>90 %). An alumina-modified colloidal silica (LUDOX CL), was used in early work to make Fe (-)/SiO2 (+) in a wet-pressed route. The highest relative density and resistivity measurements for a wet-pressing route were 87 % and 7300 +/- 1000 muO-cm respectively. Dry-pressed route is favorable over wet-pressed route because it can be commercially viable. About 100-fold increase in resistivity (860,000 muO-cm) was obtained compared to the wet-pressed route, with only a small decrease in density (1 - 2 %). A study was conducted to explore the separate, and possibly interactive, effects of micro-alumina particulate (Sumitomo AKP-50, 0.2 mum) and lubricant (Kenolube, a proprietary metal soap-wax composite lube). Reducing the LUDOX CL, high shear mixing using a coffee grinder, and multimodal packing were studied to improve density. Only 10 % reduction of LUDOX CL dropped the resistivity by over two orders of magnitude with the same relative density. High shear mixing and multimodal packing had little effects to increase density. An unmodified colloidal silica (LUDOX TM) was also explored to make Fe (+) /SiO2 (-) and resistivity of 120,000 muO-cm and 80 % density were obtained. Addition of cationic polyelectrolyte, polydiallyldimethyl-ammonium chloride (PDADMAC) was studied to provide stronger adhesion between LUDOX TM and surface of iron particles. Reducing the amount of LUDOX TM in PDADMAC showed relative density greater than 90 % but resistivity measurements were less than 1500 iU-cm.

  6. Effect of particle in-flight behavior on the composition of thermal barrier coatings

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Bai, Y.; Tang, J. J.; Liu, K.; Ding, C. H.; Yang, J. F.; Han, Z. H.

    2013-12-01

    In this work, 6 to 11 mol% YO1.5-stabilized zirconia (YSZ) coatings were deposited by supersonic and conventional atmospheric plasma spraying. During spraying, the surface temperature and velocity of in-flight particles were monitored by Spray Watch 2i on-line system. The phase composition of as-sprayed coatings was analyzed by X-ray diffractometry (XRD). Lattice parameters, tetragonality and the content of YO1.5 (mol%) of as-sprayed coatings were calculated according to the position of (0 0 4) and (4 0 0) diffraction peaks. It was found that the as-sprayed coatings were composed of metastable non-transformable tetragonal phase (t‧). However, the amount of YO1.5 (mol%) in the as-sprayed coatings decreased with the increase of melting index of in-flight particles due to the partial evaporation of YO1.5 during spraying.

  7. The effects of erodent particle size and composition on the erosion of chromium carbide based coatings

    SciTech Connect

    Walsh, P.N.; Quets, J.M.; Tucker, R.C. Jr.

    1994-12-31

    A number of studies and field experience have demonstrated the efficacy of use of chromium carbide based coatings on steam turbine components to reduce the effects of solid particle erosion. To optimize the performance of these coatings, a cost effective laboratory test is needed to facilitate the choice of coating composition, morphology, and deposition method. A variety of test types and test parameters have been reported with varying relative rankings of the various coatings evaluated. A critical review of past work has been made, with new data added for clarification. The particle size of the erodent used as well as its composition has been shown to be of particular importance. A correlation between field experience and selected laboratory test parameters then facilitates the optimum choice of coatings.

  8. Development of Diffusion barrier coatings and Deposition Technologies for Mitigating Fuel Cladding Chemical Interactions (FCCI)

    SciTech Connect

    Sridharan, Kumar; Allen, Todd; Cole, James

    2013-02-27

    The goal of this project is to develop diffusion barrier coatings on the inner cladding surface to mitigate fuel-cladding chemical interaction (FCCI). FCCI occurs due to thermal and radiation enhanced inter-diffusion between the cladding and fuel materials, and can have the detrimental effects of reducing the effective cladding wall thickness and lowering the melting points of the fuel and cladding. The research is aimed at the Advanced Burner Reactor (ABR), a sodium-cooled fast reactor, in which higher burn-ups will exacerbate the FCCI problem. This project will study both diffusion barrier coating materials and deposition technologies. Researchers will investigate pure vanadium, zirconium, and titanium metals, along with their respective oxides, on substrates of HT-9, T91, and oxide dispersion-strengthened (ODS) steels; these materials are leading candidates for ABR fuel cladding. To test the efficacy of the coating materials, the research team will perform high-temperature diffusion couple studies using both a prototypic metallic uranium fuel and a surrogate the rare-earth element lanthanum. Ion irradiation experiments will test the stability of the coating and the coating-cladding interface. A critical technological challenge is the ability to deposit uniform coatings on the inner surface of cladding. The team will develop a promising non-line-of-sight approach that uses nanofluids . Recent research has shown the feasibility of this simple yet novel approach to deposit coatings on test flats and inside small sections of claddings. Two approaches will be investigated: 1) modified electrophoretic deposition (MEPD) and 2) boiling nanofluids. The coatings will be evaluated in the as-deposited condition and after sintering.

  9. Numerical analysis of Al coating using different particle shape in LPCS

    NASA Astrophysics Data System (ADS)

    Yusof, S. N. A.; Manap, A.; Afandi, N. F.

    2016-03-01

    Cold spray (CS) is a unique spraying process where the spray materials are not melted in a spray gun. Instead, the particles are kinetically deposited on the substrate at low temperature using compressed gas. This study investigates the deposition behaviour of different particle shape of Al coating using low pressure cold sprayed (LPCS) through smoothed particle hydrodynamics (SPH) simulations, which are achieved by modelling the multiple particle impacts on Al substrate. The impact of Al particle on the Al substrate is analysed by evaluating the shape of deformation, porosity between particle, and effect of stress on the substrate. The results show that the irregular particle shapes (horizontal and vertical ellipse) tend to detach the bonded particle from the substrate and thus increase the potential risk of high tensile stress. That is really harmful to the coating quality, which never happens for spherical particle. Deposition using irregular particle exhibits tensile stress at the depth coating, whereas spherical particle exhibits compressive stress. Compressive stress is generally ensure a longer component life due to their positive effect on the fatigue life and wear resistance application.

  10. Near-frictionless carbon coatings for use in fuel injectors and pump systems operating with low-sulfur diesel fuels

    SciTech Connect

    Erdemir, A.; Ozturk, O.; Alzoubi, M.; Woodford, J.; Ajayi, L.; Fenske, G.

    2000-01-19

    While sulfur in diesel fuels helps reduce friction and prevents wear and galling in fuel pump and injector systems, it also creates environmental pollution in the form of hazardous particulates and SO{sub 2} emissions. The environmental concern is the driving force behind industry's efforts to come up with new alternative approaches to this problem. One such approach is to replace sulfur in diesel fuels with other chemicals that would maintain the antifriction and antiwear properties provided by sulfur in diesel fuels while at the same time reducing particulate emissions. A second alternative might be to surface-treat fuel injection parts (i.e., nitriding, carburizing, or coating the surfaces) to reduce or eliminate failures associated with the use of low-sulfur diesel fuels. This research explores the potential usefulness of a near-frictionless carbon (NFC) film developed at Argonne National Laboratory in alleviating the aforementioned problems. The lubricity of various diesel fuels (i.e., high-sulfur, 500 ppm; low sulfur, 140 ppm; ultra-clean, 3 ppm; and synthetic diesel or Fischer-Tropsch, zero sulfur) were tested by using both uncoated and NFC-coated 52100 steel specimens in a ball-on-three-disks and a high-frequency reciprocating wear-test rig. The test program was expanded to include some gasoline fuels as well (i.e., regular gasoline and indolene) to further substantiate the usefulness of the NFC coatings in low-sulfur gasoline environments. The results showed that the NFC coating was extremely effective in reducing wear and providing lubricity in low-sulfur or sulfur-free diesel and gasoline fuels. Specifically, depending on the wear test rig, test pair, and test media, the NFC films were able to reduce wear rates of balls and flats by factors of 8 to 83. These remarkable reductions in wear rates raise the prospect for using the ultra slick carbon coatings to alleviate problems that will be caused by the use of low sulfur diesel and gasoline fuels. Surfaces

  11. Self-assembly of graphene oxide coated soft magnetic carbonyl iron particles and their magnetorheology

    SciTech Connect

    Zhang, W. L.; Choi, H. J.

    2014-05-07

    The surface of carbonyl iron (CI) microspheres was modified with graphene oxide (GO) as a coating material using 4-aminobenzoic acid as the grafting agent. The morphology, elemental composition, and magnetic properties of the GO-coated CI (GO/CI) particles were examined by scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometry, respectively, confirming their composite formation. The magnetorheological (MR) performance of the GO/CI particle-based suspension was examined using a rotational rheometer connected to a magnetic field supply. The GO/CI particles suspension exhibited typical MR properties with increasing shear stress and viscosity depending on the applied magnetic field strength.

  12. Microstructure evolution of a ZrC coating layer in TRISO particles during high-temperature annealing

    NASA Astrophysics Data System (ADS)

    Kim, Daejong; Chun, Young Bum; Ko, Myeong Jin; Lee, Hyeon-Geun; Cho, Moon-Sung; Park, Ji Yeon; Kim, Weon-Ju

    2016-10-01

    The influence of high-temperature annealing on the microstructure of zirconium carbide (ZrC) was investigated in relation to its application as a coating layer of a nuclear fuel in a very high temperature gas cooled reactor. ZrC was deposited as a constituent coating layer of TRISO coated particles by a fluidized bed chemical vapor deposition method using a ZrCl4-CH4-Ar-H2 system. The grain growth of ZrC during high-temperature annealing was strongly influenced by the co-deposition of free carbon. Sub-stoichiometric ZrC coatings have experienced a significant grain growth during high-temperature annealing at 1800 °C and 1900 °C for 1 h. On the other hand, a dual phase of stoichiometric ZrC and free carbon experienced little grain growth. It was revealed that the free carbon of the as-deposited ZrC was primarily distributed within the ZrC grains but was redistributed to the grain boundaries after annealing. Consequently, carbon at the grain boundary retarded the grain growth of ZrC. Electron backscatter diffraction (EBSD) results showed that as-deposited ZrC had (001) a preferred orientation that kept its favored direction after significant grain growth during annealing. The hardness slightly decreased as the grain growth progressed.

  13. Detailed Reaction Kinetics for CFD Modeling of Nuclear Fuel Pellet Coating for High Temperature Gas-Cooled Reactors

    SciTech Connect

    Battaglia, Francine

    2008-11-29

    The research project was related to the Advanced Fuel Cycle Initiative and was in direct alignment with advancing knowledge in the area of Nuclear Fuel Development related to the use of TRISO fuels for high-temperature reactors. The importance of properly coating nuclear fuel pellets received a renewed interest for the safe production of nuclear power to help meet the energy requirements of the United States. High-temperature gas-cooled nuclear reactors use fuel in the form of coated uranium particles, and it is the coating process that was of importance to this project. The coating process requires four coating layers to retain radioactive fission products from escaping into the environment. The first layer consists of porous carbon and serves as a buffer layer to attenuate the fission and accommodate the fuel kernel swelling. The second (inner) layer is of pyrocarbon and provides protection from fission products and supports the third layer, which is silicon carbide. The final (outer) layer is also pyrocarbon and provides a bonding surface and protective barrier for the entire pellet. The coating procedures for the silicon carbide and the outer pyrocarbon layers require knowledge of the detailed kinetics of the reaction processes in the gas phase and at the surfaces where the particles interact with the reactor walls. The intent of this project was to acquire detailed information on the reaction kinetics for the chemical vapor deposition (CVD) of carbon and silicon carbine on uranium fuel pellets, including the location of transition state structures, evaluation of the associated activation energies, and the use of these activation energies in the prediction of reaction rate constants. After the detailed reaction kinetics were determined, the reactions were implemented and tested in a computational fluid dynamics model, MFIX. The intention was to find a reduced mechanism set to reduce the computational time for a simulation, while still providing accurate results

  14. Some parametric flow analyses of a particle bed fuel element

    SciTech Connect

    Dobranich, D.

    1993-05-01

    Parametric calculations are performed, using the SAFSIM computer program, to investigate the fluid mechanics and heat transfer performance of a particle bed fuel element. Both steady-state and transient calculations are included, addressing such issues as flow stability, reduced thrust operation, transpiration drag, coolant conductivity enhancement, flow maldistributions, decay heat removal, flow perturbations, and pulse cooling. The calculations demonstrate the dependence of the predicted results on the modeling assumptions and thus provide guidance as to where further experimental and computational investigations are needed. The calculations also demonstrate that both flow instability and flow maldistribution in the fuel element are important phenomena. Furthermore, results are encouraging that geometric design changes to the element can significantly reduce problems related to these phenomena, allowing improved performance over a wide range of element power densities and flow rates. Such design changes will help to maximize the operational efficiency of space propulsion reactors employing particle bed fuel element technology. Finally, the results demonstrate that SAFSIM is a valuable engineering tool for performing quick and inexpensive parametric simulations addressing complex flow problems.

  15. Characterization of High-Velocity Single Particle Impacts on Plasma-Sprayed Ceramic Coatings

    NASA Astrophysics Data System (ADS)

    Kiilakoski, Jarkko; Lindroos, Matti; Apostol, Marian; Koivuluoto, Heli; Kuokkala, Veli-Tapani; Vuoristo, Petri

    2016-08-01

    High-velocity impact wear can have a significant effect on the lifetime of thermally sprayed coatings in multiple applications, e.g., in the process and paper industries. Plasma-sprayed oxide coatings, such as Cr2O3- and TiO2-based coatings, are often used in these industries in wear and corrosion applications. An experimental impact study was performed on thermally sprayed ceramic coatings using the High-Velocity Particle Impactor (HVPI) at oblique angles to investigate the damage, failure, and deformation of the coated structures. The impact site was characterized by profilometry, optical microscopy, and scanning electron microscopy (SEM). Furthermore, the connection between the microstructural details and impact behavior was studied in order to reveal the damage and failure characteristics at a more comprehensive level. Differences in the fracture behavior were found between the thermally sprayed Cr2O3 and TiO2 coatings, and a concept of critical impact energy is presented here. The superior cohesion of the TiO2 coating inhibited interlamellar cracking while the Cr2O3 coating suffered greater damage at high impact energies. The HVPI experiment has proven to be able to produce valuable information about the deformation behavior of coatings under high strain rates and could be utilized further in the development of wear-resistant coatings.

  16. Surface characteristics and photoactivity of silver-modified palygorskite clays coated with nanosized titanium dioxide particles

    SciTech Connect

    Zhao Difang . E-mail: zdf6910@163.com; Zhou Jie; Liu Ning

    2007-03-15

    This paper presents the results of a study in which nanosized titanium dioxide (TiO{sub 2}) crystal particles were coated onto the surface of palygorskite fibrous clay which had been modified by silver ions using titanium tetrachloride as a precursor. Coated TiO{sub 2} particles with the anatase structure were formed after calcining at 400 deg. C for 2 h in air. Various analytical techniques were used to characterize the surface properties of titanium dioxide particles on the palygorskite. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses showed that TiO{sub 2} particles were supported on the surface of the palygorskite clays and their size was in the range of 3-6 nm. The titanium oxide coatings were found to be very active for the photocatalytic decomposition of methylene blue.

  17. Support vector machine to predict diesel engine performance and emission parameters fueled with nano-particles additive to diesel fuel

    NASA Astrophysics Data System (ADS)

    Ghanbari, M.; Najafi, G.; Ghobadian, B.; Mamat, R.; Noor, M. M.; Moosavian, A.

    2015-12-01

    This paper studies the use of adaptive Support Vector Machine (SVM) to predict the performance parameters and exhaust emissions of a diesel engine operating on nanodiesel blended fuels. In order to predict the engine parameters, the whole experimental data were randomly divided into training and testing data. For SVM modelling, different values for radial basis function (RBF) kernel width and penalty parameters (C) were considered and the optimum values were then found. The results demonstrate that SVM is capable of predicting the diesel engine performance and emissions. In the experimental step, Carbon nano tubes (CNT) (40, 80 and 120 ppm) and nano silver particles (40, 80 and 120 ppm) with nanostructure were prepared and added as additive to the diesel fuel. Six cylinders, four-stroke diesel engine was fuelled with these new blended fuels and operated at different engine speeds. Experimental test results indicated the fact that adding nano particles to diesel fuel, increased diesel engine power and torque output. For nano-diesel it was found that the brake specific fuel consumption (bsfc) was decreased compared to the net diesel fuel. The results proved that with increase of nano particles concentrations (from 40 ppm to 120 ppm) in diesel fuel, CO2 emission increased. CO emission in diesel fuel with nano-particles was lower significantly compared to pure diesel fuel. UHC emission with silver nano-diesel blended fuel decreased while with fuels that contains CNT nano particles increased. The trend of NOx emission was inverse compared to the UHC emission. With adding nano particles to the blended fuels, NOx increased compared to the net diesel fuel. The tests revealed that silver & CNT nano particles can be used as additive in diesel fuel to improve complete combustion of the fuel and reduce the exhaust emissions significantly.

  18. Electromechanical characterization of individual micron-sized metal coated polymer particles

    NASA Astrophysics Data System (ADS)

    Bazilchuk, Molly; Pettersen, Sigurd Rolland; Kristiansen, Helge; Zhang, Zhiliang; He, Jianying

    2016-06-01

    Micron-sized polymer particles with nanoscale metal coatings are essential in conductive adhesives for electronics assembly. The particles function in a compressed state in the adhesives. The link between mechanical properties and electrical conductivity is thus of the utmost importance in the formation of good electrical contact. A custom flat punch set-up based on nanoindentation has been developed to simultaneously deform and electrically probe individual particles. The set-up has a sufficiently low internal resistance to allow the measurement of sub-Ohm contact resistances. Additionally, the set-up can capture mechanical failure of the particles. Combining this data yields a fundamental understanding of contact behavior. We demonstrate that this method can clearly distinguish between particles of different sizes, with different thicknesses of metal coating, and different metallization schemes. The technique provides good repeatability and physical insight into the behavior of these particles that can guide adhesive design and the optimization of bonding processes.

  19. Particle transport in pellet fueled JET (Jet European Torus) plasmas

    SciTech Connect

    Baylor, L.R.

    1990-01-01

    Pellet fueling experiments have been carried out on the Joint European Torus (JET) tokamak with a multi-pellet injector. The pellets are injected at speeds approaching 1400 m/s and penetrate deep into the JET plasma. Highly peaked electron density profiles are achieved when penetration of the pellets approaches or goes beyond the magnetic axis, and these peaked profiles persist for more than two seconds in ohmic discharges and over one second in ICRF heated discharges. In this dissertation, analysis of electron particle transport in multi-pellet fueled JET limiter plasmas under a variety of heating conditions is described. The analysis is carried out with a one and one-half dimensional radial particle transport code to model the experimental density evolution with various particle transport coefficients. These analyses are carried out in plasmas with ohmic heating, ICRF heating, and neural beam heating, in limiter configurations. Peaked density profile cases are generally characterized by diffusion coefficients with a central (r/a < 0.5) diffusivity {approximately}0.1 m{sup 2}/s that increases rapidly to {approximately}0.3 m{sup 2}/s at r/a = 0.6 and then increases out to the plasma edge as (r/a){sup 2}. These discharges can be satisfactorily modeled without any anomalous convective (pinch) flux. 79 refs., 60 figs.

  20. Enhanced transport of Si-coated nanoscale zero-valent iron particles in porous media.

    PubMed

    HonetschlÄgerová, Lenka; Janouškovcová, Petra; Kubal, Martin

    2016-01-01

    Laboratory column experiments were conducted to evaluate the effect of previously described silica coating method on the transport of nanoscale zero-valent iron (nZVI) in porous media. The silica coating method showed the potential to prevent the agglomeration of nZVI. Transport experiments were conducted using laboratory-scale sand-packed columns at conditions that were very similar of natural groundwater. Transport properties of non-coated and silica-coated nZVI are investigated in columns of 40 cm length, which were filled with porous media. A suspension was injected in three different Fe particle concentrations (100, 500, and 1000 mg/L) at flow 5  mL/min. Experimental results were compared using nanoparticle attachment efficiency and travel distances which were calculated by classical particle filtration theory. It was found that non-coated particles were essentially immobile in porous media. In contrast, silica-coated particles showed significant transport distances at the tested conditions. Results of this study suggest that silica can increase nZVI mobility in the subsurface.

  1. Self-assembling particle-siloxane coatings for superhydrophobic concrete.

    PubMed

    Flores-Vivian, Ismael; Hejazi, Vahid; Kozhukhova, Marina I; Nosonovsky, Michael; Sobolev, Konstantin

    2013-12-26

    We report here, for the first time in the literature, a method to synthesize hydrophobic and superhydrophobic concrete. Concrete is normally a hydrophilic material, which significantly reduces the durability of concrete structures and pavements. To synthesize water-repellent concrete, hydrophobic emulsions were fabricated and applied on portland cement mortar tiles. The emulsion was enriched with the polymethyl-hydrogen siloxane oil hydrophobic agent as well as metakaolin (MK) or silica fume (SF) to induce the microroughness and polyvinyl alcohol (PVA) fibers to create hierarchical surfaces. Various emulsion types were investigated by using different mixing procedures, and single- and double-layer hydrophobic coatings were applied. The emulsions and coatings were characterized with optical microscope and scanning electron microscope (SEM), and their wetting properties, including the water contact angle (CA) and roll-off angle, were measured. A theoretical model for coated and non-coated concrete, which can be generalized for other types of materials, was developed to predict the effect of surface roughness and composition on the CA. An optimized distance between the aggregates was found where the CA has the highest value. The maximal CA measured was 156° for the specimen with PVA fibers treated with MK based emulsion. Since water penetration is the main factor leading to concrete deterioration, hydrophobic water-repellent concretes have much longer durability then regular concretes and can have a broad range of applications in civil and materials engineering.

  2. Development of electrically conductive DLC coated stainless steel separators for polymer electrolyte membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Suzuki, Yasuo; Watanabe, Masanori; Toda, Tadao; Fujii, Toshiaki

    2013-06-01

    Polymer electrolyte fuel cell (PEFC) as one of generation devices of electrical power is rapidly expanding the market as clean energy instead of petroleum and atomic energy. Residential fuel cell goes into quantity production and introduction of fuel cell for use in automobiles starts in the year 2015 in Japan. Critical subject for making fuel cell expand is how to reduce cost of fuel cell. In this paper we describe about separator plate which domains large ratio of cost in fuel cell stack. In present time, carbon is used in material of residential fuel cell separator. Metal separators are developed in fuel cell for use in automobiles because of need of mechanical strength at first. In order to make fuel cell expand in market, further cost reduction is required. But the metal separator has problem that by using metal separator contact resistance occurred by metal corrosion increases and catalyst layer and membrane degrade. In recent time we found out to protect from corrosion and dissolution of metals by coating the film of porous free conductive DLC with plasma ion implantation and deposition technology that we have developed. Film of electrically conductive DLC was formed with high speed of 13 μm/hr by ICP plasma, and coating cost breakout was performed.

  3. Metallic conductivity transition of carbon nanotube yarns coated with silver particles

    NASA Astrophysics Data System (ADS)

    Zhang, Daohong; Zhang, Yunhe; Miao, Menghe

    2014-07-01

    Dry spun carbon nanotube yarns made from vertically aligned multiwalled carbon nanotube forests possess high mechanical strength and behave like semiconductors with electrical conductivity of the order of 4 × 104 S m-1. Coating a submicron-thick film of silver particle-filled polymer on the surface increased the electrical conductivity of the carbon nanotube yarn by 60-fold without significantly sacrificing its mechanical strength. The transitional characteristics of the silver-coated carbon nanotube yarn were investigated by varying the take-up ratio of the silver coating. A step change in conductivity was observed when the silver content in the coated yarn was between 7 and 10 wt% as a result of the formation of connected silver particle networks on the carbon nanotube yarn surface.

  4. The effect of coating parameters on advanced TRISO fuels with zirconium carbide

    NASA Astrophysics Data System (ADS)

    Gehr, Dennis Franklin, II

    Recent studies of TRISO fuel behavior have shown a number of problems with the conventional SiC TRISO coating system at very high temperature, not unlike the temperatures obtainable in the very high temperature reactor (VHTR) design. These problems include but are not limited to over pressurization of the kernel due to fission gas buildup as well as kernel migration, in the presence of a temperature gradient, known as the amoeba effect. To negate these problems a solution of adding a ZrC gettering layer between the kernel and PyC buffer layer has been proposed. The purpose of this study is to provide insight into the coating parameters and how they affect the coating properties. Advanced TRISO coatings consisting of a ZrC getter are applied to surrogate kernels which represent the oxide fuel kernel of a VHTR. The coatings are then analyzed via optical and electron microscopy techniques to visually verify coating integrity. Further analysis is done using XRD to confirm that ZrC has been deposited. Density measurements are performed using a helium pycnometer to ensure coating densities meet or exceed 95% theoretical density.

  5. CoxFe1-x oxide coatings on metallic interconnects for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Shen, Fengyu; Lu, Kathy

    2016-10-01

    In order to improve the performance of Cr-containing steel as an interconnect material for solid oxide fuel cells, CoFe alloy coatings with Co:Fe ratios of 9:1, 8:2, 7:3, 6:4, and 5:5 are deposited by electrodeposition and then oxidized to CoxFe1-x oxide coatings with a thickness of ∼6 μm as protective layers on the interconnect. The area specific resistance of the coated interconnect increases with the Fe content. Higher Co content oxide coatings are more effective in limiting the growth of the chromia scale while all coatings are effective in inhibiting Cr diffusion and evaporation. With the Co0.8Fe0.2 oxide coated interconnect, the electrochemical performance of the Sm0.5Sr0.5Co0.2Fe0.8O3 cathode is improved. Only 1.54 atomic percentage of Cr is detected on the surface of the Sm0.5Sr0.5Co0.2Fe0.8O3 cathode while no Cr is detected 0.66 μm or more into the cathode. CoxFe1-x oxide coatings are promising candidates for solid oxide fuel cell interconnects with the advantage of using existing cathode species for compatibility and performance enhancement.

  6. High Power Diode Laser-Treated HP-HVOF and Twin Wire Arc-Sprayed Coatings for Fossil Fuel Power Plants

    NASA Astrophysics Data System (ADS)

    Mann, B. S.

    2013-08-01

    This article deals with high power diode laser (HPDL) surface modification of twin wire arc-sprayed (TWAS) and high pressure high velocity oxy-fuel (HP-HVOF) coatings to combat solid particle erosion occurring in fossil fuel power plants. To overcome solid particle impact wear above 673 K, Cr3C2-NiCr-, Cr3C2-CoNiCrAlY-, and WC-CrC-Ni-based HVOF coatings are used. WC-CoCr-based HVOF coatings are generally used below 673 K. Twin wire arc (TWA) spraying of Tafa 140 MXC and SHS 7170 cored wires is used for a wide range of applications for a temperature up to 1073 K. Laser surface modification of high chromium stainless steels for steam valve components and LPST blades is carried out regularly. TWA spraying using SHS 7170 cored wire, HP-HVOF coating using WC-CoCr powder, Ti6Al4V alloy, and high chromium stainless steels (X20Cr13, AISI 410, X10CrNiMoV1222, 13Cr4Ni, 17Cr4Ni) were selected in the present study. Using robotically controlled parameters, HPDL surface treatments of TWAS-coated high strength X10CrNiMoV1222 stainless steel and HP-HVOF-coated AISI 410 stainless steel samples were carried out and these were compared with HPDL-treated high chromium stainless steels and titanium alloy for high energy particle impact wear (HEPIW) resistance. The HPDL surface treatment of the coatings has improved the HEPIW resistance manifold. The improvement in HPDL-treated stainless steels and titanium alloys is marginal and it is not comparable with that of HPDL-treated coatings. These coatings were also compared with "as-sprayed" coatings for fracture toughness, microhardness, microstructure, and phase analyses. The HEPIW resistance has a strong relationship with the product of fracture toughness and microhardness of the HPDL-treated HP-HVOF and TWAS SHS 7170 coatings. This development opens up a possibility of using HPDL surface treatments in specialized areas where the problem of HEPIW is very severe. The HEPIW resistance of HPDL-treated high chromium stainless steels and

  7. An In-situ materials analysis particle probe (MAPP) diagnostic to study particle density control and hydrogenic fuel retention in NSTX

    SciTech Connect

    Allain, Jean-Paul

    2014-09-05

    A new materials analysis particle probe (MAPP) was designed, constructed and tested to develop understanding of particle control and hydrogenic fuel retention in lithium-based plasma-facing surfaces in NSTX. The novel feature of MAPP is an in-situ tool to probe the divertor NSTX floor during LLD and lithium-coating shots with subsequent transport to a post-exposure in-vacuo surface analysis chamber to measure D retention. In addition, the implications of a lithiated graphite-dominated plasma-surface environment in NSTX on LLD performance, operation and ultimately hydrogenic pumping and particle control capability are investigated in this proposal. MAPP will be an invaluable tool for erosion/redeposition simulation code validation.

  8. Solvent-free formation of hydroxyapatite coated biodegradable particles via nanoparticle-stabilized emulsion route

    NASA Astrophysics Data System (ADS)

    Okada, Masahiro; Fujii, Syuji; Nishimura, Taiki; Nakamura, Yoshinobu; Takeda, Shoji; Furuzono, Tsutomu

    2012-12-01

    Hydroxyapatite (HAp) nanoparticle-coated biodegradable polymer particles were fabricated from a nanoparticle-stabilized emulsion in the absence of any molecular surfactants or organic solvents. First, a polymer melt-in-water emulsion was prepared by mixing a water phase containing nanosized HAp particles as a particulate emulsifier and an oil phase consisting of poly(ɛ-caprolactone) (PCL) or poly(L-lactide-co-ɛ-caprolactone) (P(LLA-CL)) above its melting point. It was clarified that the interaction between ester/carboxyl groups of the polymers and the HAp nanoparticles at the polymer-water interface played a crucial role to prepare the nanoparticle-stabilized emulsion. The HAp nanoparticle-coated biodegradable polymer particle (a polymer solid-in-water emulsion) was fabricated by cooling the emulsion. The particle morphology and particle size were evaluated using scanning electron microscope.

  9. Influence of carbonyl iron particle coating with silica on the properties of magnetorheological elastomers

    NASA Astrophysics Data System (ADS)

    Małecki, P.; Królewicz, M.; Hiptmair, F.; Krzak, J.; Kaleta, J.; Major, Z.; Pigłowski, J.

    2016-10-01

    In this paper, the influence of encapsulating carbonyl iron particles with various silica coatings on the properties of magnetorheological elastomers (MREs) was investigated. A soft styrene-ethylene-butylene-styrene thermoplastic elastomer was used as the composite’s polymer matrix. Spherical carbonyl iron powder (CIP) acted as the ferromagnetic filler. In order to improve the metal-polymer interaction, carbonyl iron particles were coated with two types of single and six types of double silica layers. The first layer was created through a TMOS or TEOS hydrolysis whereas the second one was composed of organosilanes. The mechanical properties of MREs containing 38.5 vol% of CIP were analysed under dynamic loading conditions. To investigate the magnetorheological effect in these composites, a 430 mT magnetic field, generated by an array of permanent magnets, was applied during testing. The results revealed that the magnetomechanical response of the MREs differs substantially, depending on the kind of particle coating.

  10. Effect of PTFE Particle on Super-Hydrophobic Coating for Anti-Icing

    NASA Astrophysics Data System (ADS)

    Kamada, Riho; Morita, Katsuaki; Okamoto, Koji; Aoki, Akihito; Kimura, Shigeo; Sakaue, Hirotaka

    2012-11-01

    Anti/deicing of an aircraft is necessary for a safe flight operation. Mechanical processes, such as heating and deicer boot, are widely used. Deicing fluids should be coated every time before the take-off, since the fluids come off from the aircraft while cruising. We study a super-hydrophobic coating as anti-icing for an aircraft. It is designed to coat the aircraft without removal. Since a super-hydrophobic surface prevents water by reducing the surface energy, it would be another way to prevent ice on the aircraft. We provide a temperature-controlled room, which can control its temperature at the icing conditions (-14 to 0 degrees C). The contact and sliding angles are measured to study the effect of the various PTFE particles on the super-hydrophobic coatings for anti-icing. The particle diameter is varied from 5 to 30 micrometer. Comparisons among the super-hydrophobic coatings by various PTFE particles are made to discuss the performance of the resultant coatings as anti-icer.

  11. RESULTS OF TESTS TO DEMONSTRATE A SIX-INCH DIAMETER COATER FOR PRODUCTION OF TRISO-COATED PARTICLES FOR ADVANCED GAS REACTOR EXPERIMENTS

    SciTech Connect

    Douglas W. Marshall

    2008-09-01

    The Next Generation Nuclear Plant (NGNP)/Advanced Gas Reactor (AGR) Fuel Development and Qualification Program includes a series of irradiation experiments in Idaho National Laboratory's (INL's) Advanced Test Reactor. TRISOcoated particles for the first AGR experiment, AGR-1, were produced at Oak Ridge National Laboratory (ORNL) in a twoinch diameter coater. A requirement of the NGNP/AGR Program is to produce coated particles for later experiments in coaters more representative of industrial scale. Toward this end, tests have been performed by Babcock and Wilcox (B&W) in a six-inch diameter coater. These tests are expected to lead to successful fabrication of particles for the second AGR experiment, AGR-2. While a thorough study of how coating parameters affect particle properties was not the goal of these tests, the test data obtained provides insight into process parameter/coated particle property relationships. Most relationships for the six-inch diameter coater followed trends found with the ORNL two-inch coater, in spite of differences in coater design and bed hydrodynamics. For example the key coating parameters affecting pyrocarbon anisotropy were coater temperature, coating gas fraction, total gas flow rate and kernel charge size. Anisotropy of the outer pyrolytic carbon (OPyC) layer also strongly correlates with coater differential pressure. In an effort to reduce the total particle fabrication run time, silicon carbide (SiC) was deposited with methyltrichlorosilane (MTS) concentrations up to 3 mol %. Using only hydrogen as the fluidizing gas, the high concentration MTS tests resulted in particles with lower than desired SiC densities. However when hydrogen was partially replaced with argon, high SiC densities were achieved with the high MTS gas fraction.

  12. RESULTS OF TESTS TO DEMONSTRATE A SIX-INCH-DIAMETER COATER FOR PRODUCTION OF TRISO-COATED PARTICLES FOR ADVANCED GAS REACTOR EXPERIMENTS

    SciTech Connect

    Charles M Barnes

    2008-09-01

    The Next Generation Nuclear Plant (NGNP)/Advanced Gas Reactor (AGR) Fuel Development and Qualification Program includes a series of irradiation experiments in Idaho National Laboratory’s (INL’s) Advanced Test Reactor. TRISOcoated particles for the first AGR experiment, AGR-1, were produced at Oak Ridge National Laboratory (ORNL) in a two inch diameter coater. A requirement of the NGNP/AGR Program is to produce coated particles for later experiments in coaters more representative of industrial scale. Toward this end, tests have been performed by Babcock and Wilcox (B&W) in a six-inch diameter coater. These tests are expected to lead to successful fabrication of particles for the second AGR experiment, AGR-2. While a thorough study of how coating parameters affect particle properties was not the goal of these tests, the test data obtained provides insight into process parameter/coated particle property relationships. Most relationships for the six-inch diameter coater followed trends found with the ORNL two-inch coater, in spite of differences in coater design and bed hydrodynamics. For example the key coating parameters affecting pyrocarbon anisotropy were coater temperature, coating gas fraction, total gas flow rate and kernel charge size. Anisotropy of the outer pyrolytic carbon (OPyC) layer also strongly correlates with coater differential pressure. In an effort to reduce the total particle fabrication run time, silicon carbide (SiC) was deposited with methyltrichlorosilane (MTS) concentrations up to 3 mol %. Using only hydrogen as the fluidizing gas, the high concentration MTS tests resulted in particles with lower than desired SiC densities. However when hydrogen was partially replaced with argon, high SiC densities were achieved with the high MTS gas fraction.

  13. Recovery and recycling of uranium from rejected coated particles for compact high temperature reactors

    NASA Astrophysics Data System (ADS)

    Pai, Rajesh V.; Mollick, P. K.; Kumar, Ashok; Banerjee, J.; Radhakrishna, J.; Chakravartty, J. K.

    2016-05-01

    UO2 microspheres prepared by internal gelation technique were coated with pyrolytic carbon and silicon carbide using CVD technique. The particles which were not meeting the specifications were rejected. The rejected/failed UO2 based coated particles prepared by CVD technique was used for oxidation and recovery and recycling. The oxidation behaviour of sintered UO2 microspheres coated with different layers of carbon and SiC was studied by thermal techniques to develop a method for recycling and recovery of uranium from the failed/rejected coated particles. It was observed that the complete removal of outer carbon from the spheres is difficult. The crushing of microspheres enabled easier accessibility of oxygen and oxidation of carbon and uranium at 800-1000 °C. With the optimized process of multiple crushing using die & plunger and sieving the broken coated layers, we could recycle around fifty percent of the UO2 microspheres which could be directly recoated. The rest of the particles were recycled using a wet recycling method.

  14. Preparation of antibacterial composite material of natural rubber particles coated with silica and titania

    NASA Astrophysics Data System (ADS)

    Wisutiratanamanee, Apisit; Poompradub, Sirilux; Poochinda, Kunakorn

    2014-06-01

    Silica coating, followed by titania coating, was performed over spray-dried natural rubber (NR) compound for physical and anti-bacterial characterizations. Titania has a strong photo-oxidative catalytic property, which can disinfect bacteria, but may degrade NR. Therefore, silica coating was intended to form a barrier between NR and titania. First, NR particles were prepared by spray-drying of NR compound latex, formulated for household glove products, mixed with sodium dodecyl sulfate (SDS) to reduce particle agglomeration. The factorial experimental design was employed to investigate the effects of nozzle flow rate (500-700 Lh-1), inlet air temperature (110-150 °C), SDS content (35-55 phr) and mass flow rate (1.2-1.7 g rubber/min) on NR yield and moisture content. Then, the NR compound particles prepared at the optimum condition were coated with silica, using tetraethoxysilane (TEOS) as the precursor, by chemical vapor deposition (CVD) at 60 °C for 2-48 hours. Next, the particles were coated with titania using titanium tetrafluoride (TiF4) by liquid phase deposition (LPD) at 60 ºC for 4-8 hours. The NR composites were characterized for surface morphology by SEM, silica and titania content by TGA and EDX. The NR composites were found to cause more than 99% reduction of Escherichia coli and Staphylococcus aureus under 1-hour exposure to natural light.

  15. Chromium vaporization from mechanically deformed pre-coated interconnects in Solid Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Falk-Windisch, Hannes; Sattari, Mohammad; Svensson, Jan-Erik; Froitzheim, Jan

    2015-11-01

    Cathode poisoning, associated with Cr evaporation from interconnect material, is one of the most important degradation mechanisms in Solid Oxide Fuel Cells when Cr2O3-forming steels are used as the interconnect material. Coating these steels with a thin Co layer has proven to decrease Cr vaporization. To reduce production costs, it is suggested that thin metallic PVD coatings be applied to each steel strip before pressing the material into interconnect shape. This process would enable high volume production without the need for an extra post-coating step. However, when the pre-coated material is mechanically deformed, cracks may form and lower the quality of the coating. In the present study, Chromium volatilization is measured in an air-3% H2O environment at 850 °C for 336 h. Three materials coated with 600 nm Co are investigated and compared to an uncoated material. The effect of deformation is investigated on real interconnects. Microscopy observations reveal the presence of cracks in the order of several μm on the deformed pre-coated steel. However, upon exposure, the cracks can heal and form a continuous surface oxide rich in Co and Mn. As an effect of the rapid healing, no increase in Cr vaporization is measured for the pre-coated material.

  16. Size effect in Ni-coated TiC particles for metal matrix composites.

    PubMed

    Kim, Eun-Hee; Lee, David; Paik, Ungyu; Jung, Yeon-Gil

    2011-02-01

    Nickel (Ni) particles have been coated on the surface of titanium carbide (TiC) particles to enhance the dispersion of TiC particles into a molten metal and to achieve an improvement in the mechanical and thermal properties of the metal matrix. The adhesion of Ni particles on the surface of TiC particles is induced by the attractive force between the TiC with a negative charge and the Ni cation in an aqueous solution. The powders prepared with the relatively large particle sizes of 1, 4, and 40 microm show both TiC and Ni phases, whereas that prepared with a particle size of 0.02 microm shows complex phases of Ni, TiC, and TiO2 (titanium dioxide). The TiO2 phase is caused by the oxidation reaction between the TiC and oxygen. The 1 microm powder shows that the Ni is located only around the TiC without any self-aggregation and the TiC and Ni particles are isolated in the 4 and 40 microm powders, as confirmed in TEM images. The particle size is the essential factor in fabricating highly efficient Ni-coated TiC particles for metal matrix composites. PMID:21456282

  17. Estimates of helium gas release in 238PuO 2 fuel particles for radioisotope heat sources and heater units

    NASA Astrophysics Data System (ADS)

    El-Genk, Mohamed S.; Tournier, Jean-Michel

    2000-06-01

    Release data of noble gases (Xe and Kr) from small-grain (7-40 μm), large-grain (⩾300 μm), and monocrystal UO 2 fuel particles, during isothermal irradiation up to 6.4 at.% and 2030 K are reviewed and their applicability to estimate helium release from 238PuO 2 fuel particles (⩾300 μm in diameter) is examined. Coated 238PuO 2 particles have recently been proposed for use in radioisotope power systems and heater units employed in planetary exploration missions. These fuel particles are intentionally sized and designed to prevent any adverse radiological effect and retain the helium gas generated by the radioactive decay of 238Pu, a desired feature for some planetary missions. Results suggest that helium release from large-grain (⩾300 μm) particles of K could be <7% at 1723 K, <0.6% at 1042 K, and even less for polycrystalline particles fabricated using sol-gel processes. Results also suggest that helium release from small-grain plutonia particles at 1723 K could be >80% but less than 7% at 1042 K, which is in general agreement with the experiments conducted at Los Alamos National Laboratory more than two decades ago. In these experiments, the helium gas release from small-grain (7-40 μm) 238PuO 2 fuel pellets has been measured during steady-state heating at temperatures up to 1886 K and ramp heating to 1723 K.

  18. Modeled heating and surface erosion comparing motile (gas borne) and stationary (surface coating) inert particle additives

    SciTech Connect

    Buckingham, A.C.; Siekhaus, W.J.

    1982-09-27

    The unsteady, non-similar, chemically reactive, turbulent boundary layer equations are modified for gas plus dispersed solid particle mixtures, for gas phase turbulent combustion reactions and for heterogeneous gas-solid surface erosive reactions. The exterior (ballistic core) edge boundary conditions for the solutions are modified to include dispersed particle influences on core propellant combustion-generated turbulence levels, combustion reactants and products, and reaction-induced, non-isentropic mixture states. The wall surface (in this study it is always steel) is considered either bare or coated with a fixed particle coating which is conceptually non-reactive, insulative, and non-ablative. Two families of solutions are compared. These correspond to: (1) consideration of gas-borne, free-slip, almost spontaneously mobile (motile) solid particle additives which influence the turbulent heat transfer at the uncoated steel surface and, in contrast, (2) consideration of particle-free, gas phase turbulent heat transfer to the insulated surface coated by stationary particles. Significant differences in erosive heat transfer are found in comparing the two families of solutions over a substantial range of interior ballistic flow conditions. The most effective influences on reducing erosive heat transfer appear to favor mobile, gas-borne particle additives.

  19. Polypeptide-Coated Silica Particles Dispersed in Lyotropic Liquid Crystals of the Same Polypeptide.

    PubMed

    Rosu, Cornelia; Balamurugan, Sreelatha; Cueto, Rafael; Roy, Amitava; Russo, Paul S

    2016-07-28

    When a particle is introduced into a liquid crystal (LC), it distorts the LC director field, leading to new arrangements of the particles. This phenomenon is ordinarily studied using >100 nm particles and ∼2 nm mesogens. Usually the particle surface and mesogens are chemically distinct, which adds an enthalpic effect, even though the more interesting interactions are entropic. To raise the structures to the visible regime, while minimizing chemical differences between the particle surface and mesogen, silica particles coated with an α-helical polypeptide have been prepared and dispersed in lyotropic polypeptide LCs. The polypeptide is poly(γ-stearyl-α,l-glutamate) or PSLG. To make the particles easy to manipulate and easy to find, the silica core included superparamagnetic magnetite (Fe3O4) and covalently attached dye. Two methods were used to place polypeptides on these magnetic, fluorescent particles: a multistep grafting-to approach in which whole polypeptides were attached and a one-pot grafting-from approach in which the polymerization of the monomers was initiated from the particle surface. These approaches resulted in sparse and dense surface coverages, respectively. The influence of surface curvature and polypeptide molecular weight on the design of sparsely covered particles was investigated using the grafting-to approach. The aggregated grafting-from particles when freshly dispersed in a PSLG/solvent matrix disrupted the orientation of the characteristic cholesteric LC (ChLC) phase directors. In time, the hybrid particles were expelled from some domains, enabling the return of the familiar helical twist of the cholesteric mesophase. The sparsely coated grafting-to hybrid particles when inserted in the PSLG/solvent matrix assembled into stable islet-like formations that could not be disrupted even by an external magnetic field. The bulk particles aligned in chains that were easily manipulated by a magnetic field. These results indicate that

  20. SiC layer microstructure in AGR-1 and AGR-2 TRISO fuel particles and the influence of its variation on the effective diffusion of key fission products

    DOE PAGESBeta

    Gerczak, Tyler J.; Hunn, John D.; Lowden, Richard A.; Allen, Todd R.

    2016-08-15

    Tristructural isotropic (TRISO) coated particle fuel is a promising fuel form for advanced reactor concepts such as high temperature gas-cooled reactors (HTGR) and is being developed domestically under the US Department of Energy’s Nuclear Reactor Technologies Initiative in support of Advanced Reactor Technologies. The fuel development and qualification plan includes a series of fuel irradiations to demonstrate fuel performance from the laboratory to commercial scale. The first irradiation campaign, AGR-1, included four separate TRISO fuel variants composed of multiple, laboratory-scale coater batches. The second irradiation campaign, AGR-2, included TRISO fuel particles fabricated by BWX Technologies with a larger coater representativemore » of an industrial-scale system. The SiC layers of as-fabricated particles from the AGR-1 and AGR-2 irradiation campaigns have been investigated by electron backscatter diffraction (EBSD) to provide key information about the microstructural features relevant to fuel performance. The results of a comprehensive study of multiple particles from all constituent batches are reported. The observations indicate that there were microstructural differences between variants and among constituent batches in a single variant. Finally, insights on the influence of microstructure on the effective diffusivity of key fission products in the SiC layer are also discussed.« less

  1. SiC layer microstructure in AGR-1 and AGR-2 TRISO fuel particles and the influence of its variation on the effective diffusion of key fission products

    NASA Astrophysics Data System (ADS)

    Gerczak, Tyler J.; Hunn, John D.; Lowden, Richard A.; Allen, Todd R.

    2016-11-01

    Tristructural isotropic (TRISO) coated particle fuel is a promising fuel form for advanced reactor concepts such as high temperature gas-cooled reactors (HTGR) and is being developed domestically under the US Department of Energy's Nuclear Reactor Technologies Initiative in support of Advanced Reactor Technologies. The fuel development and qualification plan includes a series of fuel irradiations to demonstrate fuel performance from the laboratory to commercial scale. The first irradiation campaign, AGR-1, included four separate TRISO fuel variants composed of multiple, laboratory-scale coater batches. The second irradiation campaign, AGR-2, included TRISO fuel particles fabricated by BWX Technologies with a larger coater representative of an industrial-scale system. The SiC layers of as-fabricated particles from the AGR-1 and AGR-2 irradiation campaigns have been investigated by electron backscatter diffraction (EBSD) to provide key information about the microstructural features relevant to fuel performance. The results of a comprehensive study of multiple particles from all constituent batches are reported. The observations indicate that there were microstructural differences between variants and among constituent batches in a single variant. Insights on the influence of microstructure on the effective diffusivity of key fission products in the SiC layer are also discussed.

  2. Characterization of particle size distribution from diesel engines fueled with palm-biodiesel blends and paraffinic fuel blends

    NASA Astrophysics Data System (ADS)

    Lin, Yuan-Chung; Lee, Chia-Fon; Fang, Tiegang

    Biodiesels are promoted as alternative fuels and their applications in diesel engines have been investigated by many researchers. However, the particle size distribution emitted from heavy-duty diesel engines fueled with palm-biodiesel blended with premium diesel fuel and paraffinic fuel blended with palm-biodiesel has seldom been addressed. Thus, five test fuels were used in this work to study the particle size distribution: D100 (premium diesel fuel), B100 (100% palm-biodiesel), B20 (20 vol% palm-biodiesel+80 vol% D100), BP9505 (95 vol% paraffinic fuel+5 vol% palm-biodiesel) and BP8020 (80 vol% paraffinic fuel+20 vol% palm-biodiesel). A Micro-Orifice Uniform Deposit Impactor (MOUDI) equipped with aluminum filters was used to collect size-resolved samples. Experimental results indicated that palm-biodiesel blends and paraffinic fuel blends could improve combustion efficiency in diesel engines, but pure palm-biodiesel could cause incomplete combustion. Adding palm-biodiesel to diesel fuel would slightly increase particles with diameter <0.31 μm but paraffinic fuel blends could decrease particles with diameter <1 μm. The mass median diameter of overall particles (MMD o) and σg,o are 0.439 μm and 3.88 for D100; 0.380 μm and 3.24 for B20; 0.465 μm and 4.22 for B100; 1.40 μm and 4.92 for BP9505; 1.46 μm and 2.25 for BP8020. There are more particles with low aerodynamic diameters (diameter <0.31 μm) in the exhaust of D100, B20 and B100 fuels. On the other hand, a greater fraction of particulate matter of BP9505 and BP8020 existed in coarse particles (diameter: 2.5-10 μm). Energy efficiency also increases significantly by 12.3-15.1% with the introduction of paraffinic fuel blends into the engine. Nevertheless, paraffinic fuel blends also reduce the emission of particulate matters by 36.0-38.4%. Carbon monoxide was decreased by 36.8-48.5%. Total hydrocarbon is 39.6-41.7% less than diesel fuel combustion. Nitrogen oxides emission is about 5% lower for paraffinic

  3. Passivation of pigment particles for thermal control coatings

    NASA Technical Reports Server (NTRS)

    Farley, E. P.; Sancier, K. M.; Morrison, S. R.

    1973-01-01

    Five powders were received for plasma calcining during this report period. The particle size using a fluid energy mill, and obtained pigments that could be plasma calcined. Optimum results are obtained in the plasma calcining of zinc orthotitanate when finely dispersed particles are subjected to a calculated plasma temperature of 1670 C. Increasing the plasma calcining time by using multiple passes through the plasma stabilized the pigment to vacuum UV irradiation was evidenced by the resulting ESR spectra but slightly decreased the whiteness of the pigment. The observed darkening is apparently associated with the formation of Ti(+3) color centers.

  4. Robust superamphiphobic coatings based on silica particles bearing bifunctional random copolymers.

    PubMed

    Zhang, Ganwei; Lin, Shudong; Wyman, Ian; Zou, Hailiang; Hu, Jiwen; Liu, Guojun; Wang, Jiandong; Li, Fei; Liu, Feng; Hu, Meilong

    2013-12-26

    Reported herein is the growth of bifunctional random copolymer chains from silica particles through a "grafting from" approach and the use of these copolymer-bearing particles to fabricate superamphiphobic coatings. The silica particles had a diameter of 90 ± 7 nm and were prepared through a modified Stöber process before atom transfer radical polymerization (ATRP) initiators were introduced onto their surfaces. Bifunctional copolymer chains bearing low-surface-free-energy fluorinated units and sol-gel-forming units were then grafted from these silica particles by surface-initiated ATRP. Perfluorooctyl ethyl acrylate (FOEA) and 3-(triisopropyloxy)silylpropyl methacrylate (IPSMA) were respectively used as fluorinated and sol-gel-forming monomers in this reaction. Hydrolyzing the IPSMA units in the presence of an acid catalyst yielded silica particles that were adorned with silanol-bearing copolymer chains. Coatings were prepared by spraying these hydrolyzed silica particles onto glass and cotton substrates. A series of four different copolymer-functionalized silica particles samples bearing copolymers with similar FOEA molar fractions (fF) of ~80% but with different copolymer grafting mass ratios (gm) that ranged between 12.3 wt% and 58.8 wt%, relative to silica, were prepared by varying the polymerization protocols. These copolymer-bearing silica particles with a gm exceeding 34.1 wt% were used to coat glass and cotton substrates, yielding superamphiphobic surfaces. More importantly, these particulate-based coatings were robust and resistant to solvent extraction and NaOH etching thanks to the self-cross-linking of the copolymer chains and their covalent attachment to the substrates.

  5. Dynamics of low velocity collisions of ice particle, coated with frost

    NASA Technical Reports Server (NTRS)

    Bridges, F.; Lin, D.; Boone, L.; Darknell, D.

    1991-01-01

    We continued our investigations of low velocity collisions of ice particles for velocities in range 10(exp -3) - 2 cm/s. The work focused on two effects: (1) the sticking forces for ice particles coated with CO2 frost, and (2) the completion of a 2-D pendulum system for glancing collisions. A new computer software was also developed to control and monitor the position of the 2-D pendulum.

  6. Microstructure and thermal properties of copper–diamond composites with tungsten carbide coating on diamond particles

    SciTech Connect

    Kang, Qiping; He, Xinbo Ren, Shubin; Liu, Tingting; Liu, Qian; Wu, Mao; Qu, Xuanhui

    2015-07-15

    An effective method for preparing tungsten carbide coating on diamond surfaces was proposed to improve the interface bonding between diamond and copper. The WC coating was formed on the diamond surfaces with a reaction medium of WO{sub 3} in mixed molten NaCl–KCl salts and the copper–diamond composites were obtained by vacuum pressure infiltration of WC-coated diamond particles with pure copper. The microstructure of interface bonding between diamond and copper was discussed. Thermal conductivity and thermal expansion behavior of the obtained copper–diamond composites were investigated. Results indicated that the thermal conductivity of as-fabricated composite reached 658 W m{sup −} {sup 1} K{sup −} {sup 1}. Significant reduction in coefficient of thermal expansion of the composite compared with that of pure copper was obtained. - Highlights: • WC coating was successfully synthesized on diamond particles in molten salts. • WC coating obviously promoted the wettability of diamond and copper matrix. • WC coating greatly enhanced the thermal conductivity of Cu–diamond composite. • The composites are suitable candidates for heat sink applications.

  7. Contact Resistance and Metallurgical Connections Between Silver Coated Polymer Particles in Isotropic Conductive Adhesives

    NASA Astrophysics Data System (ADS)

    Pettersen, Sigurd R.; Kristiansen, Helge; Nagao, Shijo; Helland, Susanne; Njagi, John; Suganuma, Katsuaki; Zhang, Zhiliang; He, Jianying

    2016-07-01

    Recently, there has been an increasing interest in silver thin film coated polymer spheres as conductive fillers in isotropic conductive adhesives (ICAs). Such ICAs yield resistivities similar to conventional silver flake based ICAs while requiring only a fraction of the silver content. In this work, effects of the nanostructure of silver thin films on inter-particle contact resistance were investigated. The electrical resistivity of ICAs with similar particle content was shown to decrease with increasing coating thickness. Scanning electron micrographs of ion milled cross-sections revealed that the silver coatings formed continuous metallurgical connections at the contacts between the filler particles after adhesive curing at 150°C. The electrical resistivity decreased for all samples after environmental treatment for 3 weeks at 85°C/85% relative humidity. It was concluded that after the metallurgical connections formed, the bulk resistance of these ICAs were no longer dominated by the contact resistance, but by the geometry and nanostructure of the silver coatings. A figure of merit (FoM) was defined based on the ratio between bulk silver resistivity and the ICA resistivity, and this showed that although the resistivity was lowest in the ICAs containing the most silver, the volume of silver was more effectively used in the ICAs with intermediate silver contents. This was attributed to a size effect due to smaller grains in the thickest coating.

  8. Characterization of diesel particles: effects of fuel reformulation, exhaust aftertreatment, and engine operation on particle carbon composition and volatility.

    PubMed

    Alander, Timo J A; Leskinen, Ari P; Raunemaa, Taisto M; Rantanen, Leena

    2004-05-01

    Diesel exhaust particles are the major constituent of urban carbonaceous aerosol being linked to a large range of adverse environmental and health effects. In this work, the effects of fuel reformulation, oxidation catalyst, engine type, and engine operation parameters on diesel particle emission characteristics were investigated. Particle emissions from an indirect injection (IDI) and a direct injection (DI) engine car operating under steady-state conditions with a reformulated low-sulfur, low-aromatic fuel and a standard-grade fuel were analyzed. Organic (OC) and elemental (EC) carbon fractions of the particles were quantified by a thermal-optical transmission analysis method and particle size distributions measured with a scanning mobility particle sizer (SMPS). The particle volatility characteristics were studied with a configuration that consisted of a thermal desorption unit and an SMPS. In addition, the volatility of size-selected particles was determined with a tandem differential mobility analyzer technique. The reformulated fuel was found to produce 10-40% less particulate carbon mass compared to the standard fuel. On the basis of the carbon analysis, the organic carbon contributed 27-61% to the carbon mass of the IDI engine particle emissions, depending on the fuel and engine operation parameters. The fuel reformulation reduced the particulate organic carbon emissions by 10-55%. In the particles of the DI engine, the organic carbon contributed 14-26% to the total carbon emissions, the advanced engine technology, and the oxidation catalyst, thus reducing the OC/EC ratio of particles considerably. A relatively good consistency between the particulate organic fraction quantified with the thermal optical method and the volatile fraction measured with the thermal desorption unit and SMPS was found.

  9. Fabrication and Characterization of Surrogate Fuel Particles Using the Spark Erosion Method

    NASA Astrophysics Data System (ADS)

    Metzger, Kathryn E.

    In light of the disaster at the Fukushima Daiichi Nuclear Plant, the Department of Energy's Advanced Fuels Program has shifted its interest from enhanced performance fuels to enhanced accident tolerance fuels. Dispersion fuels possess higher thermal conductivities than traditional light water reactor fuel and as a result, offer improved safety margins. The benefits of a dispersion fuel are due to the presence of the secondary non-fissile phase (matrix), which serves as a barrier to fission products and improves the overall thermal performance of the fuel. However, the presence of a matrix material reduces the fuel volume, which lowers the fissile content of dispersion. This issue can be remedied through the development of higher density fuel phases or through an optimization of fuel particle size and volume loading. The latter requirement necessitates the development of fabrication methods to produce small, micron-order fuel particles. This research examines the capabilities of the spark erosion process to fabricate particles on the order of 10 μm. A custom-built spark erosion device by CT Electromechanica was used to produce stainless steel surrogate fuel particles in a deionized water dielectric. Three arc intensities were evaluated to determine the effect on particle size. Particles were filtered from the dielectric using a polycarbonate membrane filter and vacuum filtration system. Fabricated particles were characterized via field emission scanning electron microscopy (FESEM), laser light particle size analysis, energy-dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD), and gas pycnometry. FESEM images reveal that the spark erosion process produces highly spherical particles on the order of 10 microns. These findings are substantiated by the results of particle size analysis. Additionally, EDS and XRD results indicate the presence of oxide phases, which suggests the dielectric reacted with the molten debris during particle formation.

  10. Plasma polymerized allylamine coated quartz particles for humic acid removal.

    PubMed

    Jarvis, Karyn L; Majewski, Peter

    2012-08-15

    Allylamine plasma polymerization has been used to modify the surface of quartz particles for humic acid removal via an inductively coupled rotating barrel plasma reactor. Plasma polymerized allylamine (ppAA) films were deposited at a power of 25 W, allylamine flow rate of 4.4 sccm and polymerization times of 5-60 min. The influence of polymerization time on surface chemistry was investigated via X-ray photoelectron spectroscopy (XPS), time of flight secondary ion mass spectrometry (ToF-SIMS) and electrokinetic analysis. Acid orange 7 adsorption/desorption quantified the number of surface amine groups. Humic acid removal via ppAA quartz particles was examined by varying pH, removal time, humic acid concentration, and particle mass. Increasing the polymerization time increased the concentration of amine groups on the ppAA quartz surface, thus also increasing the isoelectric point. ToF-SIMS demonstrated uniform distribution of amine groups across the particle surface. Greatest humic acid removal was observed at pH 5 due to electrostatic attraction. At higher pH values, for longer polymerization times, humic acid removal was also observed due to hydrogen bonding. Increasing the initial humic acid concentration increased the mass of humic acid removed, with longer polymerization times exhibiting the greatest increases. Plasma polymerization using a rotating plasma reactor has shown to be a successful method for modifying quartz particles for the removal of humic acid. Further development of the plasma polymerization process and investigation of additional contaminants will aid in the development of a low cost water treatment system.

  11. Layer-by-layer self-assembly of ceramic particles for complex shape coating synthesis

    NASA Astrophysics Data System (ADS)

    Qiu, Hongwei

    Layer-by-layer (LbL) self-assembly was explored as a non-line-of-sight method for uniform infiltration and deposition of a multilayer of ceramic particles into complex structures. Key parameters for controlling the LbL self-assembly process were studied using a model system which consisted of a silicon substrate, 100 nm and 500 nm silica particles, and a polycation/polyanion combination. We correlated the surface coverage of the silica particles to the NaCl concentration used in deposition of the polyelectrolyte layers and to the number of the polyelectrolyte layers deposited. The effect of particle size on the surface coverage was rationally explained based on the screening length. We found that the effects of particle size, polydispersity, and electrolyte concentration in the particle suspension on the surface coverage and morphology of the first silica particle layer deposited on the polyelectrolyte layer surface were highly coupled, and resolving these effects was important for infiltrating a uniform coating of multilayer silica particle assemblies into a cellular structure as an ultimate complex substrate. Based on this understanding, the Lbl, self-assembly method was applied as a method of assembling, infiltrating, and immobilizing a 4-layer coating of negatively charged ˜3 mum Pd/NaAI(Si)O catalyst particles in the confined space of the cellular structure with ˜400 mum interconnected cells. The 4-layer coating deposited on the inner wall of a stainless steel capillary tube was mechanically stable under water flow rate up to 10 ml/min over the pH range of 3 to 11. Scotch tape peeling evaluation suggested that failure locations were mostly within the catalyst particle assembly, but near the assembly-PEM interface region.

  12. Creep resistant, metal-coated LiFeO[sub 2] anodes for molten carbonated fuel cells

    DOEpatents

    Khandkar, A.C.

    1994-08-23

    A porous, creep-resistant, metal-coated, LiFeO[sub 2] ceramic electrode for fuel cells is disclosed. The electrode is particularly useful for molten carbonate fuel cells (MCFC) although it may have utilities in solid oxide fuel cells (SOFC) as well. 11 figs.

  13. Creep resistant, metal-coated LiFeO.sub.2 anodes for molten carbonated fuel cells

    DOEpatents

    Khandkar, Ashok C.

    1994-01-01

    A porous, creep-resistant, metal-coated, LiFeO.sub.2 ceramic electrode for fuel cells is disclosed. The electrode is particularly useful for molten carbonate fuel cells (MCFC) although it may have utilities in solid oxide fuel cells (SOFC) as well.

  14. Low-friction coatings for air bearings in fuel cell air compressors

    SciTech Connect

    Ajayi, O. O.; Fenske, G. R.; Erdemir, A.; Woodford, J.; Sitts, J.; Elshot, K.; Griffey, K.

    2000-01-06

    In an effort to reduce fuel consumption and emissions, hybrid vehicles incorporating fuel cell systems are being developed by automotive manufacturers, their suppliers, federal agencies (specifically, the US Department of Energy) and national laboratories. The fuel cell system will require an air management subsystem that includes a compressor/expander. Certain components in the compressor will require innovative lubrication technology in order to reduce parasitic energy losses and improve their reliability and durability. One such component is the air bearing for air turbocompressors designed and fabricated by Meruit, Inc. Argonne National Laboratory recently developed a carbon-based coating with low friction and wear attributes; this near-frictionless-carbon (NFC) coating is a potential candidate for use in turbocompressor air bearings. The authors present here an evaluation of the Argonne coating for air compressor thrust bearings. With two parallel 440C stainless steel discs in unidirectional sliding contact, the NFC reduced the frictional force four times and the wear rate by more than two orders of magnitude. Wear mechanism on the uncoated surface involved oxidation and production of iron oxide debris. Wear occurred on the coated surfaces primarily by a polishing mechanism.

  15. Conducting polymer-coated corrosion resistant metallic bipolar plates for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Joseph, Shine

    2005-11-01

    addition to this, metal dissolution can contaminate the membrane electrode assembly (MEA) and can cause system failure. These problems can be solved by coating the aluminum and stainless steel alloys with corrosion resistant and conductive polymers such as polyaniline and polypyrrole. These polymers can be applied to the metallic substrates by various methods such as electrochemical deposition, spraying and painting. Corrosion and contact resistance of the coated plates were tested under fuel cell conditions and showed promising results. Coatings were characterized by microscopy, infrared spectroscopy (FTIR) and cyclic voltammetry.

  16. Vanadium diffusion coating on HT-9 cladding for mitigating the fuel cladding chemical interactions

    NASA Astrophysics Data System (ADS)

    Lo, Wei-Yang; Yang, Yong

    2014-08-01

    Fuel cladding chemical interaction (FCCI) has been identified as one of the crucial issues for developing Ferritic/Martensitic (F/M) stainless steel claddings for metallic fuels in a fast reactor. The anticipated elevated temperature and high neutron flux can significantly aggravate the FCCI, in terms of formation of inter-diffusion and lower melting point eutectic phases. To mitigate the FCCI, vanadium carbide coating as a diffusion barrier was deposited on the HT-9 substrate using a pack cementation diffusion coating (PCDC) method, and the processing temperature was optimized down to 730 °C. A solid metallurgical bonding between the coating layer and substrate was achieved, and the coating is free from through depth cracks. The microstructural characterizations using SEM and TEM show a nanostructured grain structure. EDS/WDS and XRD analysis confirm the phase of coating layer as V2C. Diffusion couple tests at 660 °C for 100 h demonstrate that V2C layer with a thickness of less than 5 μm can effectively eliminate the inter-diffusion between the lanthanide cerium and HT-9 steel.

  17. Nanocrystalline ceria coatings on solid oxide fuel cell anodes: the role of organic surfactant pretreatments on coating microstructures and sulfur tolerance.

    PubMed

    Wu, Chieh-Chun; Tang, Ling; De Guire, Mark R

    2014-01-01

    Treatments with organic surfactants, followed by the deposition of nanocrystalline ceria coatings from aqueous solution, were applied to anodes of solid oxide fuel cells. The cells were then operated in hydrogen/nitrogen fuel streams with H2S contents ranging from 0 to 500 ppm. Two surfactant treatments were studied: immersion in dodecanethiol, and a multi-step conversion of a siloxy-anchored alkyl bromide to a sulfonate functionality. The ceria coatings deposited after the thiol pretreatment, and on anodes with no pretreatment, were continuous and uniform, with thicknesses of 60-170 nm and 100-140 nm, respectively, and those cells exhibited better lifetime performance and sulfur tolerance compared to cells with untreated anodes and anodes with ceria coatings deposited after the sulfonate pretreatment. Possible explanations for the effects of the treatments on the structure of the coatings, and for the effects of the coatings on the performance of the cells, are discussed.

  18. Nanocrystalline ceria coatings on solid oxide fuel cell anodes: the role of organic surfactant pretreatments on coating microstructures and sulfur tolerance

    PubMed Central

    Wu, Chieh-Chun; Tang, Ling

    2014-01-01

    Summary Treatments with organic surfactants, followed by the deposition of nanocrystalline ceria coatings from aqueous solution, were applied to anodes of solid oxide fuel cells. The cells were then operated in hydrogen/nitrogen fuel streams with H2S contents ranging from 0 to 500 ppm. Two surfactant treatments were studied: immersion in dodecanethiol, and a multi-step conversion of a siloxy-anchored alkyl bromide to a sulfonate functionality. The ceria coatings deposited after the thiol pretreatment, and on anodes with no pretreatment, were continuous and uniform, with thicknesses of 60–170 nm and 100–140 nm, respectively, and those cells exhibited better lifetime performance and sulfur tolerance compared to cells with untreated anodes and anodes with ceria coatings deposited after the sulfonate pretreatment. Possible explanations for the effects of the treatments on the structure of the coatings, and for the effects of the coatings on the performance of the cells, are discussed. PMID:25383282

  19. Impact of the excitation source and plasmonic material on cylindrical active coated nano-particles.

    PubMed

    Arslanagic, Samel; Liu, Yan; Malureanu, Radu; Ziolkowski, Richard W

    2011-01-01

    Electromagnetic properties of cylindrical active coated nano-particles comprised of a silica nano-cylinder core layered with a plasmonic concentric nano-shell are investigated for potential nano-sensor applications. Particular attention is devoted to the near-field properties of these particles, as well as to their far-field radiation characteristics, in the presence of an electric or a magnetic line source. A constant frequency canonical gain model is used to account for the gain introduced in the dielectric part of the nano-particle, whereas three different plasmonic materials (silver, gold, and copper) are employed and compared for the nano-shell layers.

  20. Microstructure of TRISO Coated Particles from the AGR-1 Experiment I: SiC Grain Size and Grain Boundary Character

    SciTech Connect

    Rita Kirchhofer; John D, Hunn; Paul A. Demkowicz; James I. Cole; Brian P. Gorman

    2013-01-01

    Pre-irradiation SiC microstructures in TRISO coated fuel particles from the AGR-1 experiment were quantitatively characterized using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). From EBSD it was determined that only the cubic polymorph of as-deposited SiC was present and the SiC had a high fraction of CSL S3 grain boundaries. Additionally, the local area misorientation (LAM), which is a qualitative measurement of strain in the SiC lattice, was mapped for each fuel variant. The morphology of the SiC / IPyC interfaces were characterized by TEM following site-specific focused ion beam (FIB) specimen preparation. It was determined that the SiC layer had a heavily faulted microstructure typical of CVD deposited SiC and that the average grain diameter increased from the SiC/IPyC interface for all the fuel variants, except V3 that showed a constant grain size across the layer.

  1. [Pilot experiment of fluorine fixing ratio of coated lump stone coal fuel].

    PubMed

    Feng, Fu-Jian; Yu, Jiang-Ping; Wang, Wu-Yi; Luo, Kun-Li; Chen, Dai-Zhong; Li, Ying; Bai, Guang-Lu; Li, Yue; Zheng, Lai-Yi; Bai, Ai-Mei

    2005-03-01

    The pilot experiment on coated lump stone coal fuel selected from 16 families in Haoping Shanxi were studied. 8 families burned coating high fluorine lump stone coal with lime, clay and low fluorine anthracite, 8 families burned untreated lump stone coal. The results show that the fluorine-fixing ratio at treated group was 75.0% when coal fluorine compared with coal cinder fluorine. In comparison with untreated group, the concentration of door air fluoride lowered 85.7%, SO2 lowered 75.0%, dust lowered 55.3%.

  2. Ice nucleation of bare and sulfuric acid-coated mineral dust particles and implication for cloud properties

    NASA Astrophysics Data System (ADS)

    Kulkarni, Gourihar; Sanders, Cassandra; Zhang, Kai; Liu, Xiaohong; Zhao, Chun

    2014-08-01

    Ice nucleation properties of atmospherically relevant dust minerals coated with soluble materials are not yet well understood. We determined ice nucleation ability of bare and sulfuric acid-coated mineral dust particles as a function of temperature (-25 to -35°C) and relative humidity with respect to water (RHw; 75 to 110%) for five different mineral dust types: (1) Arizona test dust, (2) illite, (3) montmorillonite, (4) K-feldspar, and (5) quartz. The particles were dry dispersed and size selected at 200 nm, and we determined the fraction of dust particles nucleating ice at various temperatures and RHw. Under water-subsaturated conditions, compared to bare dust particles, we found that coated particles showed a reduction in their ice nucleation ability. Under water-supersaturated conditions, however, we did not observe a significant coating effect (i.e., the bare and coated dust particles had nearly similar nucleating properties). X-ray diffraction patterns of the coated particles indicated that acid treatment altered the crystalline nature of the surface and caused structural disorder; thus, we concluded that the lack of such structured order reduced the ice nucleation efficiency of the coated particles in deposition ice nucleation mode. In addition, our single column model results show that coated particles significantly modify cloud properties such as ice crystal number concentration and ice water content compared to bare particles in water-subsaturated conditions. However, in water-supersaturated conditions, cloud properties differ only at warmer temperatures. These modeling results imply that future aged dust particle simulations should implement coating parameterizations to accurately predict cloud properties.

  3. Multilayer and Particle Size-Graded YSZ Coatings Obtained by Plasma Spraying of Micro- and Nanostructured Feedstocks

    NASA Astrophysics Data System (ADS)

    Carpio, P.; Bannier, E.; Salvador, M. D.; Benavente, R.; Sánchez, E.

    2014-12-01

    This study was undertaken to attempt to achieve a better balance between zirconia coating properties and high-temperature performance by combining the characteristics of coatings obtained from a micro- and a nanostructured feedstock having the same YSZ composition. First, two single-layer coatings were obtained as reference coatings, using the micro- and the nanostructured feedstock, respectively. Four different composite coatings were then obtained by combining these two feedstocks. Two double-layer (multilayer) YSZ coatings were prepared by depositing the microstructured feedstock on the nanostructured layer and vice versa, while two coatings with different particle size gradients (graded coatings) were prepared by depositing various mixtures of the micro- and the nanostructured feedstock in alternate layers. The microstructure and hardness of the resulting coatings were determined. In the multilayer coatings, each layer exhibited a clearly different microstructure, whereas in the graded coatings the microstructural characteristics changed gradually. Coating hardness developed analogously, each layer displaying a marked change in hardness in the multilayer coatings in contrast to a gradual change in the graded coatings. The microstructure and hardness of the individual layers were thus quite well preserved in the developed composite coatings.

  4. Advanced oxidation of natural organic matter using hydrogen peroxide and iron-coated pumice particles.

    PubMed

    Kitis, M; Kaplan, S S

    2007-08-01

    The oxidative removal of natural organic matter (NOM) from waters using hydrogen peroxide and iron-coated pumice particles as heterogeneous catalysts was investigated. Two NOM sources were tested: humic acid solution and a natural source water. Iron coated pumice removed about half of the dissolved organic carbon (DOC) concentration at a dose of 3000 mg l(-1) in 24 h by adsorption only. Original pumice and peroxide dosed together provided UV absorbance reductions as high as 49%, mainly due to the presence of metal oxides including Al(2)O(3), Fe(2)O(3) and TiO(2) in the natural pumice, which are known to catalyze the decomposition of peroxide forming strong oxidants. Coating the original pumice particles with iron oxides significantly enhanced the removal of NOM with peroxide. A strong linear correlation was found between iron contents of coated pumices and UV absorbance reductions. Peroxide consumption also correlated with UV absorbance reduction. Control experiments proved the effective coating and the stability of iron oxide species bound on pumice surfaces. Results overall indicated that in addition to adsorptive removal of NOM by metal oxides on pumice surfaces, surface reactions between iron oxides and peroxide result in the formation of strong oxidants, probably like hydroxyl radicals, which further oxidize both adsorbed NOM and remaining NOM in solution, similar to those in Fenton-like reactions.

  5. Alpha particle spectroscopy — A useful tool for the investigation of spent nuclear fuel from high temperature gas-cooled reactors

    NASA Astrophysics Data System (ADS)

    Helmbold, M.

    1984-06-01

    For more than a decade, alpha particle spectrometry of spent nuclear fuel has been used at the Kernforschungsanlage Jülich (KFA) in the field of research for the German high temperature reactor (HTR). Techniques used for the preparation of samples for alpha spectrometry have included deposition from aqueous solutions of spent fuel, annealing of fuel particles in an oven and the evaporation of fuel material by a laser beam. The resulting sources are very thin but of low activity and the alpha spectrometry data obtained from them must be evaluated with sophisticated computer codes to achieve the required accuracy. Measurements have been made on high and low enriched uranium fuel and on a variety of parameters relevant to the fuel cycle. In this paper the source preparation and data evaluation techniques will be discussed together with the results obtained to data, i.e. production of alpha active actinide isotopes, correlations between actinide isotopes and fission products, build up and transmutation of actinides during burn-up of HTR fuel, diffusion coefficients of actinides for fuel particle kernels and coating materials. All these KFA results have helped to establish the basis for the design, licensing and operation of HTR power plants, including reprocessing and waste management.

  6. THE INFLUENCE OF CARBON BURNOUT ON SUBMICRON PARTICLE FORMATION FROM EMULSIFIED FUEL OIL COMBUSTION

    EPA Science Inventory

    The paper gives results of an examination of particle behavior and particle size distributions from the combustion of different fuel oils and emulsified fuels in three experimental combusators. Results indicate that improved carbon (C) burnout from fule oil combustion, either by...

  7. Hygroscopic growth and activation of uncoated and coated soot particles and their relation to ice nucleation

    NASA Astrophysics Data System (ADS)

    Ziese, M.; Henning, S.; Mildenberger, K.; Stratmann, F.; Möhler, O.; Benz, S.; Buchholz, A.; Mentel, Th.; Aida/Lacis-Mobile-Team

    2009-04-01

    Measurements of the hygroscopic growth (HTDMA, LACIS-mobile), activation behavior (DMT-CCNC) - scope of this paper - and ice nucleation (AIDA chamber) were performed to estimate the cloud-forming potential of pure and coated soot particles. Globally, soot particles contribute up to 2.5 % to the atmospheric aerosol. In the framework of the investigations described here, soot particles were generated either applying a graphite-spark-generator (GFG1000) or a flame-soot-generator (Mini-CAST). With respect to the hygroscopic growth and activation behavior, the influences of the carrier-gas (GFG-soot), the OC-content (CAST-soot) and of different coating materials were investigated. Differences in the hygroscopic growth and activation behavior of GFG generated soot particles were found for the two carrier-gases considered. If nitrogen was used, neither hygroscopic growth nor activation were observed. In contrast, when argon was used, particles featured a slight hygroscopic growth and were easier to activate. Hygroscopic growth increases with decreasing OC-content of the CAST-soot, up to growth factor 1.04 at 98.4 % relative humidity. Lower OC-contents also result in the particles being activated more easily. Coating with sulfuric acid enhances the hygroscopic growth and activation behavior of CAST-soot for different OC-contents. If the soot (GFG & CAST) was coated with dicarboxylic acids (oxalic and succinic acid), no enhancement of hygroscopic growth and activation was observed. This is most likely due to evaporation of the coating material. In comparison to the hygroscopic growth and activation behavior, the same trends were observed in the ice-nucleation behavior. That is, the more active a particle is as cloud condensation nuclei, the better it functions as ice nuclei. GFG-soot with argon as carrier-gas acts as a better ice nuclei than GFG-soot with nitrogen. For the CAST-soot the ice-nucleation activity decreases with increasing OC-content. Coating with sulfuric acid

  8. Fission-product retention in HTGR fuels

    SciTech Connect

    Homan, F.J.; Kania, M.J.; Tiegs, T.N.

    1982-01-01

    Retention data for gaseous and metallic fission products are presented for both Triso-coated and Biso-coated HTGR fuel particles. Performance trends are established that relate fission product retention to operating parameters, such as temperature, burnup, and neutron exposure. It is concluded that Biso-coated particles are not adequately retentive of fission gas or metallic cesium, and Triso-coated particles which retain cesium still lose silver. Design implications related to these performance trends are identified and discussed.

  9. Genotoxicity assessment of magnetic iron oxide nanoparticles with different particle sizes and surface coatings

    NASA Astrophysics Data System (ADS)

    Liu, Yanping; Xia, Qiyue; Liu, Ying; Zhang, Shuyang; Cheng, Feng; Zhong, Zhihui; Wang, Li; Li, Hongxia; Xiao, Kai

    2014-10-01

    Magnetic iron oxide nanoparticles (IONPs) have been widely used for various biomedical applications such as magnetic resonance imaging and drug delivery. However, their potential toxic effects, including genotoxicity, need to be thoroughly understood. In the present study, the genotoxicity of IONPs with different particle sizes (10, 30 nm) and surface coatings (PEG, PEI) were assessed using three standard genotoxicity assays, the Salmonella typhimurium reverse mutation assay (Ames test), the in vitro mammalian chromosome aberration test, and the in vivo micronucleus assay. In the Ames test, SMG-10 (PEG coating, 10 nm) showed a positive mutagenic response in all the five test bacterial strains with and without metabolic activation, whereas SEI-10 (PEI coating, 10 nm) showed no mutagenesis in all tester strains regardless of metabolic activation. SMG-30 (PEG coating, 30 nm) was not mutagenic in the absence of metabolic activation, and became mutagenic in the presence of metabolic activation. In the chromosomal aberration test, no increase in the incidence of chromosomal aberrations was observed for all three IONPs. In the in vivo micronucleus test, there was no evidence of increased micronuclei frequencies for all three IONPs, indicating that they were not clastogenic in vivo. Taken together, our results demonstrated that IONPs with PEG coating exhibited mutagenic activity without chromosomal and clastogenic abnormalities, and smaller IONPs (SMG-10) had stronger mutagenic potential than larger ones (SMG-30); whereas, IONPs with SEI coating (SEI-10) were not genotoxic in all three standard genotoxicity assays. This suggests that the mutagenicity of IONPs depends on their particle size and surface coating.

  10. Genotoxicity assessment of magnetic iron oxide nanoparticles with different particle sizes and surface coatings.

    PubMed

    Liu, Yanping; Xia, Qiyue; Liu, Ying; Zhang, Shuyang; Cheng, Feng; Zhong, Zhihui; Wang, Li; Li, Hongxia; Xiao, Kai

    2014-10-24

    Magnetic iron oxide nanoparticles (IONPs) have been widely used for various biomedical applications such as magnetic resonance imaging and drug delivery. However, their potential toxic effects, including genotoxicity, need to be thoroughly understood. In the present study, the genotoxicity of IONPs with different particle sizes (10, 30 nm) and surface coatings (PEG, PEI) were assessed using three standard genotoxicity assays, the Salmonella typhimurium reverse mutation assay (Ames test), the in vitro mammalian chromosome aberration test, and the in vivo micronucleus assay. In the Ames test, SMG-10 (PEG coating, 10 nm) showed a positive mutagenic response in all the five test bacterial strains with and without metabolic activation, whereas SEI-10 (PEI coating, 10 nm) showed no mutagenesis in all tester strains regardless of metabolic activation. SMG-30 (PEG coating, 30 nm) was not mutagenic in the absence of metabolic activation, and became mutagenic in the presence of metabolic activation. In the chromosomal aberration test, no increase in the incidence of chromosomal aberrations was observed for all three IONPs. In the in vivo micronucleus test, there was no evidence of increased micronuclei frequencies for all three IONPs, indicating that they were not clastogenic in vivo. Taken together, our results demonstrated that IONPs with PEG coating exhibited mutagenic activity without chromosomal and clastogenic abnormalities, and smaller IONPs (SMG-10) had stronger mutagenic potential than larger ones (SMG-30); whereas, IONPs with SEI coating (SEI-10) were not genotoxic in all three standard genotoxicity assays. This suggests that the mutagenicity of IONPs depends on their particle size and surface coating. PMID:25274166

  11. Mechanical characterization of oxide coating-interconnect interfaces for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Akanda, Sajedur R.; Walter, Mark E.; Kidner, Neil J.; Seabaugh, Matthew M.

    2012-07-01

    This paper reports on the characterization of interfaces between oxide coatings and metallic interconnects that are used in planar solid oxide fuel cells. With the reduction of operating temperatures to 800 °C, it is possible to replace ceramic interconnects with less expensive stainless steels. However, when incorporating chromia-forming metallic interconnects, steps must be taken to inhibit chromium poisoning. One approach to prevent chromium poisoning, is to deposit dense, protective coatings, such as manganese cobalt spinel oxide (MCO). The brittle nature of MCO makes it susceptible to damage under mechanical and thermal stresses during operation. A four point bend experiment is designed to assess the strength and adhesion of reduced and oxidized coatings deposited on SS441 or Crofer interconnects. Resulting tensile cracking patterns on the convex side of bend specimen are used to quantify the interfacial shear strength with a shear lag model. Using energy based fracture mechanics, interfacial fracture energy is calculated from the strain at the onset of coating spallation. Scanning electron microscopy images of the cracked coating surfaces are processed to analyze the failure mechanisms, crack spacing and spalled areas. At 3% strain, the weakest interface is found in the Crofer system with the oxidized coating.

  12. Acceptance testing of the eddy current probes for measurement of aluminum hydroxide coating thickness on K West Basin fuel elements

    SciTech Connect

    Pitner, A.L.

    1998-08-21

    During a recent visual inspection campaign of fuel elements stored in the K West Basin, it was noted that fuel elements contained in sealed aluminum canisters had a heavy translucent type coating on their surfaces (Pitner 1997a). Subsequent sampling of this coating in a hot cell (Pitner 1997b) and analysis of the material identified it as aluminum hydroxide. Because of the relatively high water content of this material, safety related concerns are raised with respect to long term storage of this fuel in Multi-Canister Overpacks (MCOs). A campaign in the basin is planned to demonstrate whether this coating can be removed by mechanical brushing (Bridges 1998). Part of this campaign involves before-and-after measurements of the coating thickness to determine the effectiveness of coating removal by the brushing machine. Measurements of the as-deposited coating thickness on multiple fuel elements are also expected to provide total coating inventory information needed for MCO safety evaluations. The measurement technique must be capable of measuring coating thicknesses on the order of several mils, with a measurement accuracy of 0.5 mil. Several different methods for quantitatively measuring these thin coatings were considered in selecting the most promising approach. Ultrasonic measurement was investigated, but it was determined that due to the thin coating depth and the high water content of the material, the signal would likely pass directly through to the cladding without ever sensing the coating surface. X-ray fluorescence was also identified as a candidate technique, but would not work because the high gamma background from the irradiated fuel would swamp out the low energy aluminum signal. Laser interferometry could possibly be applied, but considerable development would be required and it was considered to be high risk on a short term basis. The consensus reached was that standard eddy current techniques for coating thickness measurement had the best chance for

  13. Improved blend and tablet properties of fine pharmaceutical powders via dry particle coating.

    PubMed

    Huang, Zhonghui; Scicolone, James V; Han, Xi; Davé, Rajesh N

    2015-01-30

    The improvements in the flow and packing of fine pharmaceutical powder blends due to dry coating of micronized acetaminophen (mAPAP, ∼11μm), a model poorly flowing drug, are quantified. Poor flow and packing density of fine excipients (∼20μm) allowed testing the hypothesis that dry coating of cohesive API may counteract poor flow and packing of fine pharmaceutical powder blends. Further, fine excipients could improve compaction and reduce segregation tendency. It was found that flow function coefficient (FFC) and bulk density enhancements for 10%, 30%, and 60% (w/w), API loading blends with dry coated API are significantly higher than those without coated silica. At the highest API loading, for which coarser excipients were also used as reference, the flow and packing of dry coated mAPAP blends were significantly increased regardless of the excipient particle size, exceeding those of a well compacting excipient, Avicel 102. In addition, tensile strength of tablets with fine excipients was significantly higher, indicating improved compactibility. These results show for the first time that dry coating of fine, cohesive API powder leads to significantly improved flow and packing of high API loading blends consisting of fine excipients, while achieving improved tablet compactibility, suggesting suitability for direct compaction.

  14. Magnetic and optical manipulation of spherical metal-coated Janus particles

    NASA Astrophysics Data System (ADS)

    Jenness, Nathan J.; Erb, Randall M.; Yellen, Benjamin B.; Clark, Robert L.

    2010-08-01

    Spherical colloids with asymmetric surface properties, e.g., 'Janus' particles with two unique faces, are an emerging class of materials that can provide mechanisms for controlling colloidal particle dynamics. Several reports in the literature detail the fabrication of Janus particles as well as their behavior under the influence of external electric, magnetic and optical fields. Here we present an in depth study of the magnetic and optical properties of 10 μm spherical metal-coated Janus particles, and we demonstrate new mechanisms to control their assembly, transport, and achieve total positional and orientational control at the single particle level. Through the application of external magnetic fields Janus particles formed kinked-chain assemblies. Janus particles can also be transported in rotating magnetic field via hydrodynamic surface effects. Optical fields can control the rotation and clustering of Janus particles at low laser power, but not at higher powers due to the formation of cavitation bubbles and large scattering forces. The unique magnetic and optical properties of Janus particles were leveraged to engineer 'dot' Janus particles that can be utilized to achieve near holonomic control of a single colloid in an optomagnetic trap.

  15. Volatile organic compounds (VOCs) in surface coating materials: Their compositions and potential as an alternative fuel.

    PubMed

    Dinh, Trieu-Vuong; Choi, In-Young; Son, Youn-Suk; Song, Kyu-Yong; Sunwoo, Young; Kim, Jo-Chun

    2016-03-01

    A sampling system was designed to determine the composition ratios of VOCs emitted from 31 surface coating materials (SCMs). Representative architectural, automotive, and marine SCMs in Korea were investigated. Toluene, ethylbenzene, and xylene were the predominant VOCs. The VOC levels (wt%) from automotive SCMs were significantly higher than those from architectural and marine paints. It was found that target SCMs comprised mainly VOCs with 6-10 carbon atoms in molecules, which could be adsorbed by activated carbon. The saturated activated carbon which had already adsorbed toluene, ethylbenzene, and m-xylene was combusted. The saturated activated carbon was more combustible than new activated carbon because it comprised inflammable VOCs. Therefore, it could be an alternative fuel when using in a "fuelization system". To use the activated carbon as a fuel, a control technology of VOCs from a coating process was also designed and introduced.

  16. Photothermal cancer therapy using graphitic carbon–coated magnetic particles prepared by one-pot synthesis

    PubMed Central

    Lee, Hyo-Jeong; Sanetuntikul, Jakkid; Choi, Eun-Sook; Lee, Bo Ram; Kim, Jung-Hee; Kim, Eunjoo; Shanmugam, Sangaraju

    2015-01-01

    We describe here a simple synthetic strategy for the fabrication of carbon-coated Fe3O4 (Fe3O4@C) particles using a single-component precursor, iron (III) diethylenetriaminepentaacetic acid complex. Physicochemical analyses revealed that the core of the synthesized particles consists of ferromagnetic Fe3O4 material ranging several hundred nanometers, embedded in nitrogen-doped graphitic carbon with a thickness of ~120 nm. Because of their photothermal activity (absorption of near-infrared [NIR] light), the Fe3O4@C particles have been investigated for photothermal therapeutic applications. An example of one such application would be the use of Fe3O4@C particles in human adenocarcinoma A549 cells by means of NIR-triggered cell death. In this system, the Fe3O4@C can rapidly generate heat, causing >98% cell death within 10 minutes under 808 nm NIR laser irradiation (2.3 W cm−2). These Fe3O4@C particles provided a superior photothermal therapeutic effect by intratumoral delivery and NIR irradiation of tumor xenografts. These results demonstrate that one-pot synthesis of carbon-coated magnetic particles could provide promising materials for future clinical applications and encourage further investigation of this simple method. PMID:25565819

  17. Photothermal cancer therapy using graphitic carbon-coated magnetic particles prepared by one-pot synthesis.

    PubMed

    Lee, Hyo-Jeong; Sanetuntikul, Jakkid; Choi, Eun-Sook; Lee, Bo Ram; Kim, Jung-Hee; Kim, Eunjoo; Shanmugam, Sangaraju

    2015-01-01

    We describe here a simple synthetic strategy for the fabrication of carbon-coated Fe3O4 (Fe3O4@C) particles using a single-component precursor, iron (III) diethylenetriaminepentaacetic acid complex. Physicochemical analyses revealed that the core of the synthesized particles consists of ferromagnetic Fe3O4 material ranging several hundred nanometers, embedded in nitrogen-doped graphitic carbon with a thickness of ~120 nm. Because of their photothermal activity (absorption of near-infrared [NIR] light), the Fe3O4@C particles have been investigated for photothermal therapeutic applications. An example of one such application would be the use of Fe3O4@C particles in human adenocarcinoma A549 cells by means of NIR-triggered cell death. In this system, the Fe3O4@C can rapidly generate heat, causing >98% cell death within 10 minutes under 808 nm NIR laser irradiation (2.3 W cm(-2)). These Fe3O4@C particles provided a superior photothermal therapeutic effect by intratumoral delivery and NIR irradiation of tumor xenografts. These results demonstrate that one-pot synthesis of carbon-coated magnetic particles could provide promising materials for future clinical applications and encourage further investigation of this simple method.

  18. Polydopamine-Coated Magnetic Composite Particles with an Enhanced Photothermal Effect.

    PubMed

    Zheng, Rui; Wang, Sheng; Tian, Ye; Jiang, Xinguo; Fu, Deliang; Shen, Shun; Yang, Wuli

    2015-07-29

    Recently, photothermal therapy (PTT) that utilizes photothermal conversion (PTC) agents to ablate cancer under near-infrared (NIR) irradiation has attracted a growing amount of attention because of its excellent therapeutic efficacy and improved target selectivity. Therefore, exploring novel PTC agents with an outstanding photothermal effect is a current research focus. Herein, we reported a polydopamine-coated magnetic composite particle with an enhanced PTC effect, which was synthesized simply through coating polydopamine (PDA) on the surface of magnetic Fe3O4 particles. Compared with magnetic Fe3O4 particles and PDA nanospheres, the core-shell nanomaterials exhibited an increased NIR absorption, and thus, an enhanced photothermal effect was obtained. We demonstrated the in vitro and in vivo effects of the photothermal therapy using our composite particles and their ability as a contrast agent in the T2-weighted magnetic resonance imaging. These results indicated that the multifunctional composite particles with enhanced photothermal effect are superior to magnetic Fe3O4 particles and PDA nanospheres alone. PMID:26151502

  19. Polydopamine-Coated Magnetic Composite Particles with an Enhanced Photothermal Effect.

    PubMed

    Zheng, Rui; Wang, Sheng; Tian, Ye; Jiang, Xinguo; Fu, Deliang; Shen, Shun; Yang, Wuli

    2015-07-29

    Recently, photothermal therapy (PTT) that utilizes photothermal conversion (PTC) agents to ablate cancer under near-infrared (NIR) irradiation has attracted a growing amount of attention because of its excellent therapeutic efficacy and improved target selectivity. Therefore, exploring novel PTC agents with an outstanding photothermal effect is a current research focus. Herein, we reported a polydopamine-coated magnetic composite particle with an enhanced PTC effect, which was synthesized simply through coating polydopamine (PDA) on the surface of magnetic Fe3O4 particles. Compared with magnetic Fe3O4 particles and PDA nanospheres, the core-shell nanomaterials exhibited an increased NIR absorption, and thus, an enhanced photothermal effect was obtained. We demonstrated the in vitro and in vivo effects of the photothermal therapy using our composite particles and their ability as a contrast agent in the T2-weighted magnetic resonance imaging. These results indicated that the multifunctional composite particles with enhanced photothermal effect are superior to magnetic Fe3O4 particles and PDA nanospheres alone.

  20. Ice Nucleation of Bare and Sulfuric Acid-coated Mineral Dust Particles and Implication for Cloud Properties

    SciTech Connect

    Kulkarni, Gourihar R.; Sanders, Cassandra N.; Zhang, Kai; Liu, Xiaohong; Zhao, Chun

    2014-08-27

    Ice nucleation properties of different dust species coated with soluble material are not well understood. We determined the ice nucleation ability of bare and sulfuric acid coated mineral dust particles as a function of temperature (-25 to -35 deg C) and relative humidity with respect to water (RHw). Five different mineral dust species: Arizona test dust (ATD), illite, montmorillonite, quartz and kaolinite were dry dispersed and size-selected at 150 nm and exposed to sulfuric acid vapors in the coating apparatus. The condensed sulfuric acid soluble mass fraction per particle was estimated from the cloud condensation nuclei activated fraction measurements. The fraction of dust particles nucleating ice at various temperatures and RHw was determined using a compact ice chamber. In water-subsaturated conditions, compared to bare dust particles, we found that only coated ATD particles showed suppression of ice nucleation ability while other four dust species did not showed the effect of coating on the fraction of particles nucleating ice. The results suggest that interactions between the dust surface and sulfuric acid vapor are important, such that interactions may or may not modify the surface via chemical reactions with sulfuric acid. At water-supersaturated conditions we did not observed the effect of coating, i.e. the bare and coated dust particles had similar ice nucleation behavior.

  1. A highly durable fuel cell electrocatalyst based on double-polymer-coated carbon nanotubes

    PubMed Central

    Berber, Mohamed R.; Hafez, Inas H.; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

    2015-01-01

    Driven by the demand for the commercialization of fuel cell (FC) technology, we describe the design and fabrication of a highly durable FC electrocatalyst based on double-polymer-coated carbon nanotubes for use in polymer electrolyte membrane fuel cells. The fabricated electrocatalyst is composed of Pt-deposited polybenzimidazole-coated carbon nanotubes, which are further coated with Nafion. By using this electrocatalyst, a high FC performance with a power density of 375 mW/cm2 (at 70 ˚C, 50% relative humidity using air (cathode)/H2(anode)) was obtained, and a remarkable durability of 500,000 accelerated potential cycles was recorded with only a 5% loss of the initial FC potential and 20% loss of the maximum power density, which were far superior properties compared to those of the membrane electrode assembly prepared using carbon black in place of the carbon nanotubes. The present study indicates that the prepared highly durable fuel cell electrocatalyst is a promising material for the next generation of PEMFCs. PMID:26594045

  2. Nano-magnetic particles used in biomedicine: core and coating materials.

    PubMed

    Karimi, Z; Karimi, L; Shokrollahi, H

    2013-07-01

    Magnetic nanoparticles for medical applications have been developed by many researchers. Separation, immunoassay, drug delivery, magnetic resonance imaging and hyperthermia are enhanced by the use of suitable magnetic nanoparticles and coating materials in the form of ferrofluids. Due to their low biocompatibility and low dispersion in water solutions, nanoparticles that are used for biomedical applications require surface treatment. Various kinds of coating materials including organic materials (polymers), inorganic metals (gold, platinum) or metal oxides (aluminum oxide, cobalt oxide) have been attracted during the last few years. Based on the recent advances and the importance of nanomedicine in human life, this paper attempts to give a brief summary on the different ferrite nano-magnetic particles and coatings used in nanomedicine. PMID:23623057

  3. Nano-magnetic particles used in biomedicine: core and coating materials.

    PubMed

    Karimi, Z; Karimi, L; Shokrollahi, H

    2013-07-01

    Magnetic nanoparticles for medical applications have been developed by many researchers. Separation, immunoassay, drug delivery, magnetic resonance imaging and hyperthermia are enhanced by the use of suitable magnetic nanoparticles and coating materials in the form of ferrofluids. Due to their low biocompatibility and low dispersion in water solutions, nanoparticles that are used for biomedical applications require surface treatment. Various kinds of coating materials including organic materials (polymers), inorganic metals (gold, platinum) or metal oxides (aluminum oxide, cobalt oxide) have been attracted during the last few years. Based on the recent advances and the importance of nanomedicine in human life, this paper attempts to give a brief summary on the different ferrite nano-magnetic particles and coatings used in nanomedicine.

  4. New generation nuclear fuel structures: Dense particles in selectively soluble matrix

    NASA Astrophysics Data System (ADS)

    Devlin, Dave; Jarvinen, Gordon; Patterson, Brian; Pattillo, Steve; Valdez, James; Liu, X.-Y.; Phillips, Jonathan

    2009-11-01

    We have developed a technology for dispersing sub-millimeter sized fuel particles within a bulk matrix that can be selectively dissolved. This may enable the generation of advanced nuclear fuels with easy separation of actinides and fission products. The large kinetic energy of the fission products results in most of them escaping from the sub-millimeter sized fuel particles and depositing in the matrix during burning of the fuel in the reactor. After the fuel is used and allowed to cool for a period of time, the matrix can be dissolved and the fission products removed for disposal while the fuel particles are collected by filtration for recycle. The success of such an approach would meet a major goal of the GNEP program to provide advanced recycle technology for nuclear energy production. The benefits of such an approach include (1) greatly reduced cost of the actinide/fission product separation process, (2) ease of recycle of the fuel particles, and (3) a radiation barrier to prevent theft or diversion of the recycled fuel particles during the time they are re-fabricated into new fuel. In this study we describe a method to make surrogate nuclear fuels of micrometer scale W (shell)/Mo (core) or HfO 2 particles embedded in an MgO matrix that allows easy separation of the fission products and their embedded particles. In brief, the method consists of physically mixing W-Mo or hafnia particles with an MgO precursor. Heating the mixture, in air or argon, without agitation, to a temperature is required for complete decomposition of the precursor. The resulting material was examined using chemical analysis, scanning electron microscopy, X-ray diffraction and micro X-ray computed tomography and found to consist of evenly dispersed particles in an MgO + matrix. We believe this methodology can be extended to actinides and other matrix materials.

  5. New generation nuclear fuel structures: dense particles in selectively soluble matrix

    SciTech Connect

    Sickafus, Kurt E; Devlin, David J; Jarvinen, Gordon D; Patterson, Brian M; Pattillo, Steve G; Valdez, James; Phillips, Jonathan

    2009-01-01

    We have developed a technology for dispersing sub-millimeter sized fuel particles within a bulk matrix that can be selectively dissolved. This may enable the generation of advanced nuclear fuels with easy separation of actinides and fission products. The large kinetic energy of the fission products results in most of them escaping from the sub-millimeter sized fuel particles and depositing in the matrix during burning of the fuel in the reactor. After the fuel is used and allowed to cool for a period of time, the matrix can be dissolved and the fission products removed for disposal while the fuel particles are collected by filtration for recycle. The success of such an approach would meet a major goal of the GNEP program to provide advanced recycle technology for nuclear energy production. The benefits of such an approach include (1) greatly reduced cost of the actinide/fission product separation process, (2) ease of recycle of the fuel particles, and (3) a radiation barrier to prevent theft or diversion of the recycled fuel particles during the time they are re-fabricated into new fuel. In this study we describe a method to make surrogate nuclear fuels of micrometer scale W (shell)/Mo (core) or HfO2 particles embedded in an MgO matrix that allows easy separation of the fission products and their embedded particles. In brief, the method consists of physically mixing W-Mo or hafnia particles with an MgO precursor. Heating the mixture, in air or argon, without agitation, to a temperature is required for complete decomposition of the precursor. The resulting material was examined using chemical analysis, scanning electron microscopy, X-ray diffraction and micro X-ray computed tomography and found to consist of evenly dispersed particles in an MgO + matrix. We believe this methodology can be extended to actinides and other matrix materials.

  6. Stability of EUV multilayer coatings to low energy alpha particles bombardment.

    PubMed

    Nardello, M; Zuppella, Paola; Polito, V; Corso, Alain Jody; Zuccon, Sara; Pelizzo, M G

    2013-11-18

    Future solar missions will investigate the Sun from very close distances and optical components are constantly exposed to low energy ions irradiation. In this work we present the results of a new experiment related to low energy alpha particles bombardments on Mo/Si multilayer optical coatings. Different multilayer samples, with and without a protecting capping layer, have been exposed to low energy alpha particles (4keV), fixing the ions fluency and varying the time of exposure in order to change the total dose accumulated. The experimental parameters have been selected considering the potential application of the coatings to future solar missions. Results show that the physical processes occurred at the uppermost interfaces can strongly damage the structure. PMID:24514344

  7. Development of metal-coated ceramic anodes for molten carbonate fuel cells

    SciTech Connect

    Khandkar, A.C.; Elangovan, S.; Marianowski, L.G.

    1990-03-01

    This report documents the developmental efforts on metal coating of various ceramic substrates (LiAlO{sub 2}, SrTiO{sub 3}, and LiFeO{sub 2}) and the critical issues associated with fabricating anodes using metal-coated LiAlO{sub 2} substrates. Electroless Ni and Cu coating technology was developed to achieve complete metal coverage on LiAlO{sub 2} powder substrates. Metal coated SrTiO{sub 3} powders were fabricated into anodes by a process identical to that reported in the GE literature. Microstructural examination revealed that the grains of the ceramic had fused together, with the metal having dewetted from the surface of the ceramic. Alternate substrates that might allow for better wetting of the metal on the ceramic such as LiFeO{sub 2} and Li{sub 2}MnO{sub 3} were identified. Cu/Ni-coated (50:50 mol ratio, 50 w/o metal loading) LiFeO{sub 2} anodes were optimized to meet the MCFC anode specifications. Metal-coated gamma-LiAlO{sub 2} substrates were also developed. By using suitable chemical surface modification methods, the gamma-UAlO{sub 2} substrate surface may be modified to allow a stable metal coated anode to be fabricated. Creep testing of the metal coated ceramic anodes were conducted at IGT. It was determined that the predominant creep mechanism is due to particle rearrangement. The anode porosity, and mean pore size had significant effect on the creep of the anode. Lower porosity and pore size consistent with performance criteria are desired to reduce creep. Lower metal loading with uniformity of coverage will result in lower creep behavior of the anode. Of the two substrates evaluated, LiFeO{sub 2} in general exhibited lower creep which was attributed to superior metal adhesion.

  8. Development of metal-coated ceramic anodes for molten carbonate fuel cells. Final report

    SciTech Connect

    Khandkar, A.C.; Elangovan, S.; Marianowski, L.G.

    1990-03-01

    This report documents the developmental efforts on metal coating of various ceramic substrates (LiAlO{sub 2}, SrTiO{sub 3}, and LiFeO{sub 2}) and the critical issues associated with fabricating anodes using metal-coated LiAlO{sub 2} substrates. Electroless Ni and Cu coating technology was developed to achieve complete metal coverage on LiAlO{sub 2} powder substrates. Metal coated SrTiO{sub 3} powders were fabricated into anodes by a process identical to that reported in the GE literature. Microstructural examination revealed that the grains of the ceramic had fused together, with the metal having dewetted from the surface of the ceramic. Alternate substrates that might allow for better wetting of the metal on the ceramic such as LiFeO{sub 2} and Li{sub 2}MnO{sub 3} were identified. Cu/Ni-coated (50:50 mol ratio, 50 w/o metal loading) LiFeO{sub 2} anodes were optimized to meet the MCFC anode specifications. Metal-coated gamma-LiAlO{sub 2} substrates were also developed. By using suitable chemical surface modification methods, the gamma-UAlO{sub 2} substrate surface may be modified to allow a stable metal coated anode to be fabricated. Creep testing of the metal coated ceramic anodes were conducted at IGT. It was determined that the predominant creep mechanism is due to particle rearrangement. The anode porosity, and mean pore size had significant effect on the creep of the anode. Lower porosity and pore size consistent with performance criteria are desired to reduce creep. Lower metal loading with uniformity of coverage will result in lower creep behavior of the anode. Of the two substrates evaluated, LiFeO{sub 2} in general exhibited lower creep which was attributed to superior metal adhesion.

  9. Chemical compositions of black carbon particle cores and coatings via soot particle aerosol mass spectrometry with photoionization and electron ionization.

    PubMed

    Canagaratna, Manjula R; Massoli, Paola; Browne, Eleanor C; Franklin, Jonathan P; Wilson, Kevin R; Onasch, Timothy B; Kirchstetter, Thomas W; Fortner, Edward C; Kolb, Charles E; Jayne, John T; Kroll, Jesse H; Worsnop, Douglas R

    2015-05-14

    Black carbon is an important constituent of atmospheric aerosol particle matter (PM) with significant effects on the global radiation budget and on human health. The soot particle aerosol mass spectrometer (SP-AMS) has been developed and deployed for real-time ambient measurements of refractory carbon particles. In the SP-AMS, black carbon or metallic particles are vaporized through absorption of 1064 nm light from a CW Nd:YAG laser. This scheme allows for continuous "soft" vaporization of both core and coating materials. The main focus of this work is to characterize the extent to which this vaporization scheme provides enhanced chemical composition information about aerosol particles. This information is difficult to extract from standard SP-AMS mass spectra because they are complicated by extensive fragmentation from the harsh 70 eV EI ionization scheme that is typically used in these instruments. Thus, in this work synchotron-generated vacuum ultraviolet (VUV) light in the 8-14 eV range is used to measure VUV-SP-AMS spectra with minimal fragmentation. VUV-SP-AMS spectra of commercially available carbon black, fullerene black, and laboratory generated flame soots were obtained. Small carbon cluster cations (C(+)-C5(+)) were found to dominate the VUV-SP-AMS spectra of all the samples, indicating that the corresponding neutral clusters are key products of the SP vaporization process. Intercomparisons of carbon cluster ratios observed in VUV-SP-AMS and SP-AMS spectra are used to confirm spectral features that could be used to distinguish between different types of refractory carbon particles. VUV-SP-AMS spectra of oxidized organic species adsorbed on absorbing cores are also examined and found to display less thermally induced decomposition and fragmentation than spectra obtained with thermal vaporization at 200 °C (the minimum temperature needed to quantitatively vaporize ambient oxidized organic aerosol with a continuously heated surface). The particle cores

  10. Chemical compositions of black carbon particle cores and coatings via soot particle aerosol mass spectrometry with photoionization and electron ionization.

    PubMed

    Canagaratna, Manjula R; Massoli, Paola; Browne, Eleanor C; Franklin, Jonathan P; Wilson, Kevin R; Onasch, Timothy B; Kirchstetter, Thomas W; Fortner, Edward C; Kolb, Charles E; Jayne, John T; Kroll, Jesse H; Worsnop, Douglas R

    2015-05-14

    Black carbon is an important constituent of atmospheric aerosol particle matter (PM) with significant effects on the global radiation budget and on human health. The soot particle aerosol mass spectrometer (SP-AMS) has been developed and deployed for real-time ambient measurements of refractory carbon particles. In the SP-AMS, black carbon or metallic particles are vaporized through absorption of 1064 nm light from a CW Nd:YAG laser. This scheme allows for continuous "soft" vaporization of both core and coating materials. The main focus of this work is to characterize the extent to which this vaporization scheme provides enhanced chemical composition information about aerosol particles. This information is difficult to extract from standard SP-AMS mass spectra because they are complicated by extensive fragmentation from the harsh 70 eV EI ionization scheme that is typically used in these instruments. Thus, in this work synchotron-generated vacuum ultraviolet (VUV) light in the 8-14 eV range is used to measure VUV-SP-AMS spectra with minimal fragmentation. VUV-SP-AMS spectra of commercially available carbon black, fullerene black, and laboratory generated flame soots were obtained. Small carbon cluster cations (C(+)-C5(+)) were found to dominate the VUV-SP-AMS spectra of all the samples, indicating that the corresponding neutral clusters are key products of the SP vaporization process. Intercomparisons of carbon cluster ratios observed in VUV-SP-AMS and SP-AMS spectra are used to confirm spectral features that could be used to distinguish between different types of refractory carbon particles. VUV-SP-AMS spectra of oxidized organic species adsorbed on absorbing cores are also examined and found to display less thermally induced decomposition and fragmentation than spectra obtained with thermal vaporization at 200 °C (the minimum temperature needed to quantitatively vaporize ambient oxidized organic aerosol with a continuously heated surface). The particle cores

  11. Improved microbial fuel cell performance by encapsulating microbial cells with a nickel-coated sponge.

    PubMed

    Liu, Xueying; Du, Xiaoyu; Wang, Xia; Li, Naiqiang; Xu, Ping; Ding, Yi

    2013-03-15

    Development of novel anodic materials that could facilitate microbial biofilm formation, substrate transfer, and electron transfer is vital to enhance the performance of microbial fuel cells (MFCs). In this work, nickel-coated sponge, as a novel and inexpensive material with an open three-dimensional macro-porous structure, was employed as an anode to encapsulate microbial cells. Compared with planar carbon paper, the nickel-coated sponge did not only offer a high surface area to facilitate microbial cells attachment and colonization but also supported sufficient substrate transfer and electron transfer due to multiplexed and highly conductive pathways. As expected, the resulting nickel-coated sponge biofilm demonstrated excellent electrochemical activity and power output stability during electricity generation processes. A higher maximum power density of 996 mW m(-2) and a longer, more stable electricity generation period were achieved with the nickel-coated sponge biofilm than previously reported results. Notably, chemical oxygen demand (COD) removal reached 90.3% in the anode chamber, suggesting that the nickel-coated sponge is a highly promising anodic material and an efficient immobilization method for the fabrication of MFCs. PMID:22939511

  12. Life prediction of coated and uncoated metallic interconnect for solid oxide fuel cell applications

    NASA Astrophysics Data System (ADS)

    Liu, W. N.; Sun, X.; Stephens, E.; Khaleel, M. A.

    In this paper, we present an integrated experimental and modeling methodology in predicting the life of coated and uncoated metallic interconnect (IC) for solid oxide fuel cell (SOFC) applications. The ultimate goal is to provide cell designer and manufacture with a predictive methodology such that the life of the IC system can be managed and optimized through different coating thickness to meet the overall cell designed life. Crofer 22 APU is used as the example IC material system. The life of coated and uncoated Crofer 22 APU under isothermal cooling was predicted by comparing the predicted interfacial strength and the interfacial stresses induced by the cooling process from the operating temperature to room temperature, together with the measured oxide scale growth kinetics. It was found that the interfacial strength between the oxide scale and the Crofer 22 APU substrate decreases with the growth of the oxide scale, and that the interfacial strength for the oxide scale/spinel coating interface is much higher than that of the oxide scale/Crofer 22 APU substrate interface. As expected, the predicted life of the coated Crofer 22 APU is significantly longer than that of the uncoated Crofer 22 APU.

  13. Anticorrosion properties of tin oxide coatings for carbonaceous bipolar plates of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Kinumoto, Taro; Nagano, Keita; Yamamoto, Yuji; Tsumura, Tomoki; Toyoda, Masahiro

    2014-03-01

    An anticorrosive surface treatment of a carbonaceous bipolar plate used in proton exchange membrane fuel cells (PEMFCs) was demonstrated by addition of a tin oxide surface coating by liquid phase deposition (LPD), and its effectiveness toward corrosion prevention was determined. The tin oxide coating was deposited by immersion in tin fluoride and boric acid solutions, without any observable decrease in the bipolar plate electrical conductivity. Anticorrosion properties of a flat carbonaceous bipolar plate were investigated in an aqueous HClO4 electrolyte solution (10 μmol dm-3) at 80 °C. CO2 release due to corrosion was significant for the bare specimen above 1.3 V, whereas no CO2 release was noted for the tin-oxide-coated specimen, even approaching 1.5 V. Moreover, minimal changes in contact angle against a water droplet before and after treatment indicated suppressed corrosion of the surface-coated specimen. Anticorrosion properties were also confirmed for a model bipolar plate having four gas flow channels. The tin oxide layer remained on the channel surfaces (inner walls, corners and intersections) after durability tests. Based on these results, tin-oxide-based surface coatings fabricated by LPD show promise as an anticorrosion technique for carbonaceous bipolar plates for PEMFCs.

  14. Multilayer (TiN, TiAlN) ceramic coatings for nuclear fuel cladding

    NASA Astrophysics Data System (ADS)

    Alat, Ece; Motta, Arthur T.; Comstock, Robert J.; Partezana, Jonna M.; Wolfe, Douglas E.

    2016-09-01

    In an attempt to develop an accident-tolerant fuel (ATF) that can delay the deleterious consequences of loss-of-coolant-accidents (LOCA), multilayer coatings were deposited onto ZIRLO® coupon substrates by cathodic arc physical vapor deposition (CA-PVD). Coatings were composed of alternating TiN (top) and Ti1-xAlxN (2-layer, 4-layer, 8-layer and 16-layer) layers. The minimum TiN top coating thickness and coating architecture were optimized for good corrosion and oxidation resistance. Corrosion tests were performed in static pure water at 360 °C and 18.7 MPa for up to 90 days. The optimized coatings showed no spallation/delamination and had a maximum of 6 mg/dm2 weight gain, which is 6 times smaller than that of a control sample of uncoated ZIRLO® which showed a weight gain of 40.2 mg/dm2. The optimized architecture features a ∼1 μm TiN top layer to prevent boehmite phase formation during corrosion and a TiN/TiAlN 8-layer architecture which provides the best corrosion performance.

  15. Electrostatic separation of superconducting particles from non-superconducting particles and improvement in fuel atomization by electrorheology

    NASA Astrophysics Data System (ADS)

    Chhabria, Deepika

    This thesis has two major topics: (1) Electrostatic Separation of Superconducting Particles from a Mixture of Non-Superconducting Particles. (2) Improvement in fuel atomization by Electrorheology. (1) Based on the basic science research, the interactions between electric field and superconductors, we have developed a new technology, which can separate superconducting granular particles from their mixture with non-superconducting particles. The electric-field induced formation of superconducting balls is important aspect of the interaction between superconducting particles and electric field. When the applied electric field exceeds a critical value, the induced positive surface energy on the superconducting particles forces them to aggregate into balls or cling to the electrodes. In fabrication of superconducting materials, especially HTSC materials, it is common to come across materials with multiple phases: some grains are in superconducting state while the others are not. Our technology is proven to be very useful in separating superconducting grains from the rest non-superconducting materials. To separate superconducting particles from normal conducting particles, we apply a suitable strong electric field. The superconducting particles cling to the electrodes, while normal conducting particles bounce between the electrodes. The superconducting particles could then be collected from the electrodes. To separate superconducting particles from insulating ones, we apply a moderate electric field to force insulating particles to the electrodes to form short chains while the superconducting particles are collected from the middle of capacitor. The importance of this technology is evidenced by the unsuccessful efforts to utilize the Meissner effect to separate superconducting particles from nonsuperconducting ones. Because the Meissner effect is proportional to the particle volume, it has been found that the Meissner effect is not useful when the superconducting

  16. [Implantation of collagen coated hydroxyapatite particles. A clinical-histological study in humans].

    PubMed

    Sanz, M; Bascones, A; Kessler, A; García Nuñez, J; Newman, M G; Robertson, M A; Carranza, F A

    1989-05-01

    In this study, histologic behaviour of collagen coated hydroxylapatite particles implanted in human periodontal osseous defects has been analyzed. This material was surgically implanted in four patients, and reentry and block biopsies were carried out 4 and 6 months later. The histologic results demonstrate that this material is well tolerated by surrounding tissues, not eliciting an inflammatory reaction. At four months, the hydroxylapatite particles appear encapsulated by a very cellular connective tissue and at 6 months are found in direct contact with osteoid and mature bone. This material acts as a filler material, being fully biocompatible and stimulating an osseoconductive reaction of the adjacent alveolar bone. PMID:2637052

  17. [Implantation of collagen coated hydroxyapatite particles. A clinical-histological study in humans].

    PubMed

    Sanz, M; Bascones, A; Kessler, A; García Nuñez, J; Newman, M G; Robertson, M A; Carranza, F A

    1989-05-01

    In this study, histologic behaviour of collagen coated hydroxylapatite particles implanted in human periodontal osseous defects has been analyzed. This material was surgically implanted in four patients, and reentry and block biopsies were carried out 4 and 6 months later. The histologic results demonstrate that this material is well tolerated by surrounding tissues, not eliciting an inflammatory reaction. At four months, the hydroxylapatite particles appear encapsulated by a very cellular connective tissue and at 6 months are found in direct contact with osteoid and mature bone. This material acts as a filler material, being fully biocompatible and stimulating an osseoconductive reaction of the adjacent alveolar bone.

  18. Probing the adhesion of particles to responsive polymer coatings with hydrodynamic shear stresses

    NASA Astrophysics Data System (ADS)

    Toomey, Ryan; Efe, Gulnur

    2015-03-01

    Lower critical solution temperature (LCST) polymers in confined geometries have found success in applications that benefit from reversible modulation of surface properties, including drug delivery, separations, tissue cultures, and chromatography. In this talk, we present the adhesion of polystyrene microspheres to cross-linked poly(N-isopropylacrylamide), or poly(NIPAAm) coatings, as studied with a spinning disk method. This method applies a linear range of hydrodynamic shear forces to physically adsorbed microspheres along the radius of a coated disk. Quantification of detachment is accomplished by optical microscopy to evaluate the minimum shear stress to remove adherent particles. Experiments were performed to assess the relationship between the surface chemistry of the microsphere, the thickness and cross-link density of the poly(NIPAAm) coating, the adsorption (or incubation) time, and the temperature on the detachment profiles of the microspheres. Results show that both the shear modulus and slow dynamic processes in the poly(NIPAAm) films strongly influence the detachment shear stresses. Moreover, whether an adsorbed microsphere can be released (through a modulation in the swelling of the poly(NIPAAm) coating by temperature) depends on both the surface chemistry of the microsphere and the extent of the adsorption time. Finally, the results show that the structure of the poly(NIPAAm) coating can significantly affect performance, which may explain several of the conflicting findings that have been reported in the literature.

  19. Fuel particles in the Chernobyl cooling pond: current state and prediction for remediation options.

    PubMed

    Bulgakov, A; Konoplev, A; Smith, J; Laptev, G; Voitsekhovich, O

    2009-04-01

    During the coming years, a management and remediation strategy for the Chernobyl cooling pond (CP) will be implemented. Remediation options include a controlled reduction in surface water level of the cooling pond and stabilisation of exposed sediments. In terrestrial soils, fuel particles deposited during the Chernobyl accident have now almost completely disintegrated. However, in the CP sediments the majority of (90)Sr activity is still in the form of fuel particles. Due to the low dissolved oxygen concentration and high pH, dissolution of fuel particles in the CP sediments is significantly slower than in soils. After the planned cessation of water pumping from the Pripyat River to the Pond, significant areas of sediments will be drained and exposed to the air. This will significantly enhance the dissolution rate and, correspondingly, the mobility and bioavailability of radionuclides will increase with time. The rate of acidification of exposed bottom sediments was predicted on the basis of acidification of similar soils after liming. Using empirical equations relating the fuel particle dissolution rate to soil and sediment pH allowed prediction of fuel particle dissolution and (90)Sr mobilisation for different remediation scenarios. It is shown that in exposed sediments, fuel particles will be almost completely dissolved in 15-25 years, while in parts of the cooling pond which remain flooded, fuel particle dissolution will take about a century. PMID:19185396

  20. Advanced electron microscopic techniques applied to the characterization of irradiation effects and fission product identification of irradiated TRISO coated particles from the AGR-1 experiment

    SciTech Connect

    Rooyen, I.J. van; Lillo, T.M.; Trowbridge, T.L.; Madden, J.M.; Wu, Y.Q.; Goran, D.

    2013-07-01

    Preliminary electron microscopy of coated fuel particles from the AGR-1 experiment was conducted using characterization techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and wavelength dispersive spectroscopy (WDS). Microscopic quantification of fission-product precipitates was performed. Although numerous micro- and nano-sized precipitates observed in the coating layers during initial SEM characterization of the cross-sections, and in subsequent TEM diffraction patterns, were indexed as UPd{sub 2}Si{sub 2}, no Ag was conclusively found. Additionally, characterization of these precipitates highlighted the difficulty of measuring low concentrations of Ag in precipitates in the presence of significantly higher concentrations of Pd and U. The electron microscopy team followed a multi-directional and phased approach in the identification of fission products in irradiated TRISO fuel. The advanced electron microscopy techniques discussed in this paper, not only demonstrate the usefulness of the equipment (methods) as relevant research tools, but also provide relevant scientific results which increase the knowledge about TRISO fuel particles microstructure and fission products transport.

  1. Kaolinite particles as ice nuclei: learning from the use of different types of kaolinite and different coatings

    NASA Astrophysics Data System (ADS)

    Wex, H.; DeMott, P. J.; Tobo, Y.; Hartmann, S.; Rösch, M.; Clauss, T.; Tomsche, L.; Niedermeier, D.; Stratmann, F.

    2013-11-01

    Kaolinite particles from two different sources (Fluka and Clay Minerals Society (CMS)) were examined with respect to their ability to act as ice nuclei. This was done in the water subsaturated regime where often deposition ice nucleation is assumed to occur, and for water supersaturated conditions, i.e. in the immersion freezing mode. Measurements were done using a flow tube (LACIS) and a continuous flow diffusion chamber (CFDC). Pure and coated particles were used, with coating thicknesses of a few nanometer or less, where the coating consisted of either levoglucosan, succinic acid, or sulfuric acid. In general, it was found that the coatings strongly reduced deposition ice nucleation. Remaining ice formation in the water subsaturated regime could be attributed to immersion freezing, with particles immersed in concentrated solutions formed by the coatings. In the immersion freezing mode, ice nucleation rate coefficients, jhet, from both instruments agreed with each other when the residence times in the instruments were accounted for. Fluka kaolinite particles coated with either levoglucosan or succinic acid showed the same IN activity as pure Fluka kaolinite particles, i.e. it can be assumed that these two types of coating did not alter the ice active surface chemically, and that the coatings were diluted enough in the droplets that were formed prior to the ice nucleation, so that freezing point depression was negligible. However, Fluka kaolinite particles which were coated with either pure sulfuric acid or which were first coated with the acid and then exposed to additional water vapor both showed a reduced ability to nucleate ice, compared to the pure particles. For the CMS kaolinite particles, the ability to nucleate ice in the immersion freezing mode was similar for all examined particles, i.e. for the pure ones and the ones with the different types of coating. Moreover, jhet derived for the CMS kaolinite particles was comparable to jhet derived for kaolinite

  2. Organic grain coatings in primitive interplanetary dust particles: Implications for grain sticking in the Solar Nebula

    NASA Astrophysics Data System (ADS)

    Flynn, George J.; Wirick, Sue; Keller, Lindsay P.

    2013-10-01

    The chondritic porous interplanetary dust particles (CP IDPs), fragments of asteroids and comets collected by NASA high-altitude research aircraft from the Earth's stratosphere, are recognized as the least altered samples of the original dust of the Solar Nebula available for laboratory examination. We performed high-resolution, ~25 nm/pixel, x-ray imaging and spectroscopy on ultramicrotome sections of CP IDPs, which are aggregates of >104 grains, and identified and characterized ~100 nm thick coatings of organic matter on the surfaces of the individual grains. We estimated the minimum tensile strength of this organic glue to be ~150 to 325 N/m2, comparable to the strength of the weakest cometary meteors, based on the observation that the individual grains of ~5 μm diameter aggregate CP IDPs are not ejected from the particle by electrostatic repulsion due to charging of these IDPs to 10 to 15 volts at 1 A.U. in space. Since organic coatings can increase the sticking coefficient over that of bare mineral grains, these organic grain coatings are likely to have been a significant aid in grain sticking in the Solar Nebula, allowing the first dust particles to aggregate over a much wider range of collision speeds than for bare mineral grains.

  3. Polyethyleneimine coating of magnetic particles increased the stability of an immobilized diglycosidase.

    PubMed

    Minig, Marisol; Mazzaferro, Laura S; Capecce, Agostina; Breccia, Javier D

    2015-01-01

    The diglycosidase, α-rhamnosyl-β-glucosidase, from Acremonium sp. DSM24697 was immobilized by adsorption and cross-linking onto polyaniline-iron (PI) particles. The immobilization yield and the immobilization efficiency were relatively high, 31.2% and 8.9%, respectively. However, the heterogeneous preparation showed lower stability in comparison with the soluble form of the enzyme in operational conditions at 60 °C. One parameter involved in the reduced stability of the heterogeneous preparation was the protein metal-catalyzed oxidation achieved by iron traces supplied from the support. To overcome the harmful effect, iron particles were coated with polyethyleneimine (PEI; 0.84 mg/g) previously for the immobilization of the catalyst. The increased stability of the catalyst was correlated with the amount of iron released from the support. Under operational conditions, the uncoated particles lost between 76% and 52% activity after two cycles of reuse, whereas the PEI-coated preparation reduced 45-28% activity after five cycles of reuse in the range of pH 5.0-10, respectively. Hence, polymer coating of magnetic materials used as enzyme supports might be an interesting approach to improve the performance of biotransformation processes.

  4. Characterization of MgO-coated-LiCoO2 particles by analytical transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Taguchi, Noboru; Akita, Tomoki; Tatsumi, Kuniaki; Sakaebe, Hikari

    2016-10-01

    The surfaces of LiCoO2 particles were modified to improve the charge-discharge cycling properties of Li-ion batteries containing LiCoO2 cathodes. The sol-gel technique was used to modify the surface of LiCoO2 particles with magnesium oxide. Capacity retention during cycling of the magnesium oxide-coated LiCoO2 cathode was superior to that of a cathode comprising pristine LiCoO2. Moreover, results obtained from TEM measurements indicate that the Li concentration was relatively homogeneous in the magnesium oxide-coated LiCoO2 particles after cycling tests. The crystallographic planes of the coating were found to be coherently oriented with those of the substrate, MgO(111)[1-10]//LiCoO2(003)[100]. Therefore, we believe that a thin cover of Mg on the surface of LiCoO2 stabilizes the surface, contributing to the homogeneity of charge and discharge reactions.

  5. Polyethyleneimine coating of magnetic particles increased the stability of an immobilized diglycosidase.

    PubMed

    Minig, Marisol; Mazzaferro, Laura S; Capecce, Agostina; Breccia, Javier D

    2015-01-01

    The diglycosidase, α-rhamnosyl-β-glucosidase, from Acremonium sp. DSM24697 was immobilized by adsorption and cross-linking onto polyaniline-iron (PI) particles. The immobilization yield and the immobilization efficiency were relatively high, 31.2% and 8.9%, respectively. However, the heterogeneous preparation showed lower stability in comparison with the soluble form of the enzyme in operational conditions at 60 °C. One parameter involved in the reduced stability of the heterogeneous preparation was the protein metal-catalyzed oxidation achieved by iron traces supplied from the support. To overcome the harmful effect, iron particles were coated with polyethyleneimine (PEI; 0.84 mg/g) previously for the immobilization of the catalyst. The increased stability of the catalyst was correlated with the amount of iron released from the support. Under operational conditions, the uncoated particles lost between 76% and 52% activity after two cycles of reuse, whereas the PEI-coated preparation reduced 45-28% activity after five cycles of reuse in the range of pH 5.0-10, respectively. Hence, polymer coating of magnetic materials used as enzyme supports might be an interesting approach to improve the performance of biotransformation processes. PMID:24698389

  6. The structural-phase state of iron-carbon coatings formed by the ultradispersed particles

    SciTech Connect

    Manakova, Irina A. Ozernoy, Alexey N. Tuleushev, Yuriy Zh. Vereshchak, Mikhail F. Volodin, Valeriy N. Zhakanbayev, Yeldar A.

    2014-10-27

    The methods of nuclear gamma-resonance spectroscopy, elemental microanalysis, and X-ray diffraction were used to study nanoscale coatings. The samples were prepared by magnetron sputtering of carbon and iron particles. They alternately were deposited on monocrystalline silicon or polycrystalline corundum substrate moving relative to the plasma flows in the form of sublayers with a thickness of less than 0.6 nm up to the total thickness of 150-500 nm. Solid solutions with the carbon concentrations of up to 7.5, 12.0, 17.6, and 23.9 at% were produced by co-precipitation of ultradispersed particles of iron and carbon. Using method of conversion electron Mössbauer spectroscopy, we detected the anisotropy of orientation of magnetic moments of iron atoms due to texturing of the formed coatings. The deviation of the crystallite orientation from the average value depends on the degree of carbonization. At 550°C, the pearlite eutectic α‐Fe(C)+Fe{sub 3}C is formed from the amorphous structure without formation of intermediate carbides. The relative content of cementite correlates with the amount of carbon in the coating. The formation of the solid solutions-alloys directly during the deposition process confirms the theory of thermal-fluctuation melting of small particles.

  7. Development of Thermal Spraying and Coating Techniques by Using Thixotropic Slurries Including Metals and Ceramics Particles

    NASA Astrophysics Data System (ADS)

    Kirihara, S.; Itakura, Y.; Tasaki, S.

    2013-03-01

    Thermal nanoparticles coating and microlines patterning were newly developed as novel technologies to fabricate fine ceramics layers and geometrical intermetallics patterns for mechanical properties modulations of practical alloys substrates. Nanometer sized alumina particles were dispersed into acrylic liquid resins, and the obtained slurries were sputtered by using compressed air jet. The slurry mists could blow into the arc plasma with argon gas spraying. On stainless steels substrates, the fine surface layers with high wear resistance were formed. In cross sectional microstructures of the coated layers, micromater sized cracks or pores were not observed. Subsequently, pure aluminum particles were dispersed into photo solidified acrylic resins, and the slurry was spread on the stainless steel substrates by using a mechanical knife blade. On the substrates, microline patterns with self similar fractal structures were drawn and fixed by using scanning of an ultra violet laser beam. The patterned pure metal particles were heated by the argon arc plasma spray assisting, and the intermetallics or alloys phases with high hardness were created through reaction diffusions. Microstructures in the coated layers and the patterned lines were observed by using a scanning electron microscopy.

  8. Titanium dioxide reinforced hydroxyapatite coatings deposited by high velocity oxy-fuel (HVOF) spray.

    PubMed

    Li, H; Khor, K A; Cheang, P

    2002-01-01

    Hydroxyapatite (HA) coatings with titania addition were produced by the high velocity oxy-fuel (HVOF) spray process. Mechanical properties of the as-sprayed coatings in terms of adhesive strength, shear strength and fracture toughness were investigated to reveal the effect of the titania reinforcement on HA. Qualitative phase analysis with X-ray diffraction (XRD) showed that mutual chemical reaction between TiO2 and HA, that formed CaTiO3 occurred during coating formation. Differential scanning calorimetry (DSC) analysis of the starting powders showed that the mutual chemical reaction temperature was approximately 1410 degrees C and the existence of TiO2 can effectively inhibit the decomposition of HA at elevated temperatures. The positive influence of TiO2 addition on the shear strength was revealed. The incorporation of 10 vol% TiO2 significantly improved the Young's modulus of HA coatings from 24.82 (+/- 2.44) GPa to 43.23 (+/- 3.20) GPa. It decreased to 38.51 (+/- 3.65) GPa as the amount of TiO2 increased to 20 vol%. However, the addition of TiO2 has a negative bias on the adhesive strength of HA coatings especially when the content of TiO2 reached 20 vol%. This is attributed to the weak chemical bonding and brittle phases existing at the splats' interface that resulted from mutual chemical reactions. The fracture toughness exhibited values of 0.48 (+/- 0.08) MPa m0.5, 0.60 (+/- 0.07) MPa m0.5 and 0.67 (+/- 0.06) MPa m0.5 for the HA coating, 10 vol% TiO2 blended HA coating and 20 vol% TiO2 blended HA coating respectively. The addition of TiO2 in HA coating with the amount of less than 20 vol% is suggested for satisfactory toughening effect in HVOF HA coating. PMID:11762858

  9. Characterization of Ceramic Plasma-Sprayed Coatings, and Interaction Studies Between U-Zr Fuel and Ceramic Coated Interface at an Elevated Temperature

    SciTech Connect

    Ki Hwan Kim; Chong Tak Lee; R. S. Fielding; J. R. Kennedy

    2011-08-01

    Candidate coating materials for re-usable metallic nuclear fuel crucibles, HfN, TiC, ZrC, and Y2O3, were plasma-sprayed onto niobium substrates. The coating microstructure and the thermal cycling behavior were characterized, and U-Zr melt interaction studies carried out. The Y2O3 coating layer had a uniform thickness and was well consolidated with a few small pores scattered throughout. While the HfN coating was not well consolidated with a considerable amount of porosity, but showed somewhat uniform thickness. Thermal cycling tests on the HfN, TiC, ZrC, and Y2O3 coatings showed good cycling characteristics with no interconnected cracks forming even after 20 cycles. Interaction studies done on the coated samples by dipping into a U-20wt.%Zr melt indicated that HfN and Y2O3 did not form significant reaction layers between the melt and the coating while the TiC and the ZrC coatings were significantly degraded. Y2O3 exhibited the most promising performance among HfN, TiC, ZrC, and Y2O3 coatings.

  10. Targeted lipid-coated nanoparticles: delivery of tumor necrosis factor-functionalized particles to tumor cells.

    PubMed

    Messerschmidt, Sylvia K E; Musyanovych, Anna; Altvater, Martin; Scheurich, Peter; Pfizenmaier, Klaus; Landfester, Katharina; Kontermann, Roland E

    2009-07-01

    Polymeric nanoparticles displaying tumor necrosis factor on their surface (TNF nanocytes) are useful carrier systems capable of mimicking the bioactivity of membrane-bound TNF. Thus, TNF nanocytes are potent activators of TNF receptor 1 and 2 leading to a striking enhancement of apoptosis. However, in vivo applications are hampered by potential systemic toxicity. Here, using TNF nanocytes as a model system, we developed a procedure to generate targeted lipid-coated particles (TLP) in which TNF activity is shielded. The TLPs generated here are composed of an inner single-chain TNF (scTNF)-functionalized, polymeric nanoparticle core surrounded by a lipid coat endowed with polyethylene glycol (PEG) for sterical stabilization and a single-chain Fv (scFv) fragment for targeting. Using a scFv directed against the tumor stroma marker fibroblast activation protein (FAP) we show that TLP and scTNF-TLP specifically bind to FAP-expressing, but not to FAP-negative cells. Lipid coating strongly reduced nonspecific binding of particles and scTNF-mediated cytotoxicity towards FAP-negative cells. In contrast, an increased cytotoxicity of TLP was observed for FAP-positive cells. Thus, through liposome encapsulation, nanoparticles carrying bioactive molecules, which are subject to nonselective uptake and activity towards various cells and tissues, can be converted into target cell-specific composite particles exhibiting a selective activity towards antigen-positive target cells. Besides safe and targeted delivery of death ligands such as TNF, TLP should be suitable for various diagnostic and therapeutic applications, which benefit from a targeted delivery of reagents embedded into the particle core or displayed on the core particle surface.

  11. TRISO-Coated Fuel Processing to Support High Temperature Gas-Cooled Reactors

    SciTech Connect

    Del Cul, G.D.

    2002-10-01

    The initial objective of the work described herein was to identify potential methods and technologies needed to disassemble and dissolve graphite-encapsulated, ceramic-coated gas-cooled-reactor spent fuels so that the oxide fuel components can be separated by means of chemical processing. The purpose of this processing is to recover (1) unburned fuel for recycle, (2) long-lived actinides and fission products for transmutation, and (3) other fission products for disposal in acceptable waste forms. Follow-on objectives were to identify and select the most promising candidate flow sheets for experimental evaluation and demonstration and to address the needs to reduce technical risks of the selected technologies. High-temperature gas-cooled reactors (HTGRs) may be deployed in the next -20 years to (1) enable the use of highly efficient gas turbines for producing electricity and (2) provide high-temperature process heat for use in chemical processes, such as the production of hydrogen for use as clean-burning transportation fuel. Also, HTGR fuels are capable of significantly higher burn-up than light-water-reactor (LWR) fuels or fast-reactor (FR) fuels; thus, the HTGR fuels can be used efficiently for transmutation of fissile materials and long-lived actinides and fission products, thereby reducing the inventory of such hazardous and proliferation-prone materials. The ''deep-burn'' concept, described in this report, is an example of this capability. Processing of spent graphite-encapsulated, ceramic-coated fuels presents challenges different from those of processing spent LWR fuels. LWR fuels are processed commercially in Europe and Japan; however, similar infrastructure is not available for processing of the HTGR fuels. Laboratory studies on the processing of HTGR fuels were performed in the United States in the 1960s and 1970s, but no engineering-scale processes were demonstrated. Currently, new regulations concerning emissions will impact the technologies used in

  12. Thermosensitive polymer (N-isopropylacrylamide) coated nanomagnetic particles: preparation and characterization.

    PubMed

    Shamim, N; Hong, L; Hidajat, K; Uddin, M S

    2007-03-15

    Thermosensitive polymer coated nanomagnetic adsorbents were synthesized by seed polymerization using surface modified nanomagnetic particles as the seeds. The Fe3O4 nanomagnetic particles were prepared by chemical precipitation of Fe2+ and Fe3+ salts in the ratio of 1:2 under alkaline and inert condition. The surface of these particles was modified by surfactants to achieve stability against agglomeration. These stable particles were then polymerized using N-isopropylacrylamide (NIPAM) as the main monomer, methylene-bis-acrylamide as the crosslinker and potassium per sulfate as the initiator. The thermosensitive adsorbents were characterized by using transmission electron micrography (TEM) and vibrating sample magnetometer (VSM). TEM showed that the particle remained discrete with a mean diameter of 12 nm. Magnetic measurements revealed that the particles are superparamagnetic only with a decrease of magnetism after binding with the polymer due to the increase in surface spin disorientation. Pure Fe3O4 spinel structure of these nanoparticles was indicated by the X-ray diffraction (XRD) patterns. The polymerization of NIPAM with the surface modified nanomagnetic particles was confirmed by Fourier transform spectroscopy (FTIR), Thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). In addition, the adsorption/desorption of BSA molecule on these thermosensitive nanoparticles was investigated as a function of temperature. More than 60% desorption efficiency was achieved under appropriate condition. PMID:17178452

  13. The Self-Assembled Nanophase Particle (SNAP) Process: A Nanoscience Approach to Coatings

    SciTech Connect

    Donley, Michael S.; Mantz, Robert A.; Khramov, A. N.; Balbyshev, Vsevolod; Kasten, Linda S.; Gaspar, Dan J.

    2003-09-15

    In the corrosion protection of aluminum-skinned aircraft, surface pretreatment and cleaning are critical steps in protecting aerospace alloys from corrosion. Our recent discovery of a revolutionary new method of forming functionalized silica nanoparticles in situ in an aqueous-based sol-gel process, and then crosslinking the nanoparticles to form a thin film, is an excellent example of a nanoscience approach to coatings. This coating method is called the self-assembled nanophase particle (SNAP) process. The SNAP coating process consists of three stages: (1) sol-gel processing; (2) SNAP solution mixing; (3) SNAP coating application and cure. Here, we report on key parameters in the ''sol-gel processing'' and the ''coating application and cure'' stages in the GPTMS/TMOS system. The SNAP process is discussed from the formation of the nanosized macromolecules to the coating application and curing process. The ''sol-gel processing'' stage involves hydrolysis and condensation reactions and is controlled by the solution pH and water content. Here, the molar ratio of water to hydrolysable silane is a key factor. SNAP solutions have been investigated by NMR, IR, light scattering, and GPC to identify molecular condensation structures formed as a function of aging time in the solution. In moderate pH and highwater content solutions, hydrolysis occurs rapidly and condensation kinetic conditions are optimized to generate nanophase siloxane macromolecules. In the ''SNAP solution mixing'' stage, crosslinking agents and additives are added to the solution, which is then applied to a substrate by dip-coating to form the SNAP coating. The chemical structure and morphology of the films have been characterized using X-ray diffraction (XRD), time-of-flight secondary ion mass spectrometry (TOF-SIMS) and atomic force microscopy (AFM). SNAP films are amorphous but exhibit nanostructured assembly of siloxane oligomers at a separation of about 1.8 nm as well as molecular level ordering of O

  14. An electrochemical immunosensor for carcinoembryonic antigen enhanced by self-assembled nanogold coatings on magnetic particles.

    PubMed

    Li, Jianping; Gao, Huiling; Chen, Zhiqiang; Wei, Xiaoping; Yang, Catherine F

    2010-04-14

    A quick and reproducible electrochemical-based immunosensor technique, using magnetic core/shell particles that are coated with self-assembled multilayer of nanogold, has been developed. Magnetic particles that are structured from Au/Fe(3)O(4) core-shells were prepared and aminated after a reaction between gold and thiourea, and additional multilayered coatings of gold nanoparticles were assembled on the surface of the core/shell particles. The carcinoembryonic antibody (anti-CEA) was immobilized on the modified magnetic particles, which were then attached on the surface of solid paraffin carbon paste electrode (SPCE) by an external magnetic field. This is an assembly of a novel immuno biosensor for carcinoembryonic antigen (CEA). The sensitivity and response features of this immunoassay are significantly affected by the surface area and the biological compatibility of the multilayered nanogold. The linear range for the detection of CEA was from 0.005 to 50 ng mL(-1) and the limit of detection (LOD) was 0.001 ng mL(-1). The LOD is approximately 500 times more sensitive than that of the traditional enzyme-linked immunosorbent assay for CEA detection.

  15. Ultrasonic cavitation erosion of high-velocity oxygen-fuel (HVOF) sprayed near-nanostructured WC-10Co-4Cr coating in NaCl solution.

    PubMed

    Hong, Sheng; Wu, Yuping; Zhang, Jianfeng; Zheng, Yugui; Qin, Yujiao; Lin, Jinran

    2015-09-01

    The high-velocity oxygen-fuel (HVOF) spraying process was used to prepare near-nanostructured WC-10Co-4Cr coating. The cavitation erosion behavior and mechanism of the coating in 3.5 wt.% NaCl solution were analyzed in detail. The results showed that the amorphous phase and WC grain were present in the coating. The cavitation erosion resistance of the coating was about 1.27 times that of the stainless steel 1Cr18Ni9Ti under the same testing conditions. The effects of erosion time on the microstructural evolution were discussed. It was revealed that cracks initiated at the edge of pre-existing pores and propagated along the carbide-binder interface, leading to the pull-out of carbide particle and the formation of pits and craters on the surface. The main failure mechanism of the coating was erosion of the binder phases, brittle detachment of hard phases and formation of pitting corrosion products. PMID:25617967

  16. Fuel to Oxidizer Ratio Effects on La2O3 Nano Particles

    NASA Astrophysics Data System (ADS)

    Reddy, G. Balanagi; Bikshalu, K.; Rao, K. Venkateswara; Aparna, Y.; Shekar, M. Chandra; Prasad, K. Eswara

    2011-07-01

    The present paper deals with the synthesis of lanthanum oxide or lanthana (La2O3) nano particles. Lanthana nano particles were synthesized using chemical combustion synthesis based on glycine (C2H5NO2). The fuel glycine is varied for different fuel to oxidizer ratios (O/F). The starting material (oxidizer) is the lanthanum nitrate (La(NO3)3.9H2O). These lanthana nano particles were characterized by thermogravimetry (TG) and differential thermal analysis (DTA) for thermal studies, X-ray diffraction (XRD) for crystal structure analysis, Scanning electron microscopy (SEM) for morphological and particle size determination.

  17. STEM-EDS analysis of fission products in neutron-irradiated TRISO fuel particles from AGR-1 experiment

    NASA Astrophysics Data System (ADS)

    Leng, B.; van Rooyen, I. J.; Wu, Y. Q.; Szlufarska, I.; Sridharan, K.

    2016-07-01

    Historic and recent post-irradiation-examination from the German AVR and Advanced Gas Reactor Fuel Development and Qualification Project have shown that 110 m Ag is released from intact tristructural isotropic (TRISO) fuel. Although TRISO fuel particle research has been performed over the last few decades, little is known about how metallic fission products are transported through the SiC layer, and it was not until March 2013 that Ag was first identified in the SiC layer of a neutron-irradiated TRISO fuel particle. The existence of Pd- and Ag-rich grain boundary precipitates, triple junction precipitates, and Pd nano-sized intragranular precipitates in neutron-irradiated TRISO particle coatings was investigated using Scanning Transmission Electron Microscopy and Energy Dispersive Spectroscopy analysis to obtain more information on the chemical composition of the fission product precipitates. A U-rich fission product honeycomb shape precipitate network was found near a micron-sized precipitate in a SiC grain about ∼5 μm from the SiC-inner pyrolytic carbon interlayer, indicating a possible intragranular transport path for uranium. A single Ag-Pd nano-sized precipitate was found inside a SiC grain, and this is the first research showing such finding in irradiated SiC. This finding may possibly suggest a possible Pd-assisted intragranular transport mechanism for Ag and may be related to void or dislocation networks inside SiC grains. Preliminary semi-quantitative analysis indicated the micron-sized precipitates to be Pd2Si2U with carbon existing inside these precipitates. However, the results of such analysis for nano-sized precipitates may be influenced by the SiC matrix. The results reported in this paper confirm the co-existence of Cd with Ag in triple points reported previously.

  18. In vitro performance of ceramic coatings obtained by high velocity oxy-fuel spray.

    PubMed

    Melero, H; Garcia-Giralt, N; Fernández, J; Díez-Pérez, A; Guilemany, J M

    2014-01-01

    Hydroxyapatite coatings obtained by plasma-spraying have been used for many years to improve biological performance of bone implants, but several studies have drawn attention to the problems arising from high temperatures and the lack of mechanical properties. In this study, plasma-spraying is substituted by high velocity oxy-fuel (HVOF) spray, with lower temperatures reached, and TiO2 is added in low amounts to hydroxyapatite in order to improve the mechanical properties. Four conditions have been tested to evaluate which are those with better biological properties. Viability and proliferation tests, as well as differentiation assays and morphology observation, are performed with human osteoblast cultures onto the studied coatings. The hydroxyapatite-TiO2 coatings maintain good cell viability and proliferation, especially the cases with higher amorphous phase amount and specific surface, and promote excellent differentiation, with a higher ALP amount for these cases than for polystyrene controls. Observation by SEM corroborates this excellent behaviour. In conclusion, these coatings are a good alternative to those used industrially, and an interesting issue would be improving biological behaviour of the worst cases, which in turn show the better mechanical properties.

  19. Diffusion Barrier Properties of Nitride-Based Coatings on Fuel Cladding

    SciTech Connect

    Fauzia Khatkhatay; Jie Jian; Liang Jiao; Qing Su; Jian Gan; James I. Cole; Haiyan Wang

    2013-12-01

    In this work titanium nitride (TiN) and zirconium nitride (ZrN) coatings are proposed as diffusion barriers between stainless steel nuclear fuel cladding and lanthanide fission products. TiN and ZrN have been coated as barrier materials between pure Fe and Ce, i.e. diffusion couples of Fe/TiN/Ce and Fe/ZrN/Ce, annealed up to a temperature of 600 degrees C, and compared to the diffusion behavior of uncoated Fe/Ce. Backscattered electron images and electron dispersive X-ray spectroscopy measurements confirm that, with a 500 nm TiN or ZrN layer, no obvious diffusion is observed between Fe and Ce. Basic diffusion characteristics of the Fe/Ce couple have also been measured and compared with the TiN and ZrN coated ones. The results strongly advocate that TiN and ZrN coatings provide reliable diffusion barrier characteristics against Ce and possibly other lanthanide fission products.

  20. Fabrication of bifunctional core-shell Fe3O4 particles coated with ultrathin phosphor layer

    PubMed Central

    2013-01-01

    Bifunctional monodispersed Fe3O4 particles coated with an ultrathin Y2O3:Tb3+ shell layer were fabricated using a facile urea-based homogeneous precipitation method. The obtained composite particles were characterized by powder X-ray diffraction, transmission electron microscopy (TEM), quantum design vibrating sample magnetometry, and photoluminescence (PL) spectroscopy. TEM revealed uniform spherical core-shell-structured composites ranging in size from 306 to 330 nm with a shell thickness of approximately 25 nm. PL spectroscopy confirmed that the synthesized composites displayed a strong eye-visible green light emission. Magnetic measurements indicated that the composite particles obtained also exhibited strong superparamagnetic behavior at room temperature. Therefore, the inner Fe3O4 core and outer Y2O3:Tb3+ shell layer endow the composites with both robust magnetic properties and strong eye-visible luminescent properties. These composite materials have potential use in magnetic targeting and bioseparation, simultaneously coupled with luminescent imaging. PMID:23962025

  1. Comparison of oil and fuel particle chemical signatures with particle emissions from heavy and light duty vehicles

    NASA Astrophysics Data System (ADS)

    Spencer, Matthew T.; Shields, Laura G.; Sodeman, David A.; Toner, Stephen M.; Prather, Kimberly A.

    In order to establish effective vehicle emission control strategies, efforts are underway to perform studies which provide insight into the origin of the source of vehicle particle emissions. In this study, the mass spectral signatures of individual particles produced from atomized auto and diesel oil and fuel samples were obtained using aerosol time-of-flight mass spectrometry (ATOFMS). The major particle types produced by these samples show distinct chemistry, falling into several major categories for each sample. Lubricating oils contain calcium and phosphate based additives and although the additives are present in low abundance (˜1-2% by mass), calcium and phosphate ions dominate the mass spectra for all new and used oil samples. Mass spectra from used oil contain more elemental carbon (EC) and organic carbon (OC) marker ions when compared to new oils and exhibit a very high degree of similarity to heavy duty diesel vehicle (HDDV) exhaust particles sampled by an ATOFMS. Fewer similarities exist between the used oil particles and light duty vehicle (LDV) emissions. Diesel and unleaded fuel mass spectra contain polycyclic aromatic hydrocarbon (PAH) molecular ions, as well as intense PAH fragment ions 25(C 2H) -, 49(C 4H) -, and inorganic ions 23Na +, 39K +, 95(PO 4) -. Unleaded fuel produced spectra which contained Na + and K +; likewise, LDV particle emission spectra also contained Na + and K +. Comparing oil and fuel particle signatures with HDDV and LDV emissions enhances our ability to differentiate between these sources and understand the origin of specific marker ions from these major ambient particle sources.

  2. Method of Forming a Composite Coating with Particle Materials that are Readily Dispersed in a Sprayable Polyimide Solution

    NASA Technical Reports Server (NTRS)

    Tran, Sang Q. (Inventor)

    1998-01-01

    A method for creating a composite form of coating from a sprayable solution of soluble polyimides and particle materials that are uniformly dispersed within the solution is described. The coating is formed by adding a soluble polyimide to a solvent, then stirring particle materials into the solution. The composite solution is sprayed onto a substrate and heated in an oven for a period of time in order to partially remove the solvent. The process may be repeated until the desired thickness or characteristic of the coating is obtained. The polyimide is then heated to at least 495 F, so that it is no longer soluble.

  3. Crystallographic study of Si and ZrN coated U-Mo atomised particles and of their interaction with al under thermal annealing

    NASA Astrophysics Data System (ADS)

    Zweifel, T.; Palancher, H.; Leenaers, A.; Bonnin, A.; Honkimaki, V.; Tucoulou, R.; Van Den Berghe, S.; Jungwirth, R.; Charollais, F.; Petry, W.

    2013-11-01

    A new type of high density fuel is needed for the conversion of research and test reactors from high to lower enriched uranium. The most promising one is a dispersion of atomized uranium-molybdenum (U-Mo) particles in an Al matrix. However, during in-pile irradiation the growth of an interaction layer between the U-Mo and the Al matrix strongly limits the fuel's performance. To improve the in-pile behaviour, the U-Mo particles can be coated with protective layers. The SELENIUM (Surface Engineering of Low ENrIched Uranium-Molybdenum) fuel development project consists of the production, irradiation and post-irradiation examination of 2 flat, full-size dispersion fuel plates containing respectively Si and ZrN coated U-Mo atomized powder dispersed in a pure Al matrix. In this paper X-ray diffraction analyses of the Si and ZrN layers after deposition, fuel plate manufacturing and thermal annealing are reported. It was found for the U-Mo particles coated with ZrN (thickness 1 μm), that the layer is crystalline, and exhibits lower density than the theoretical one. Fuel plate manufacturing does not strongly influence these crystallographic features. For the U-Mo particles coated with Si (thickness 0.6 μm), the measurements of the as received material suggest an amorphous state of the deposited layer. Fuel plate manufacturing strongly modifies its composition: Si reacts with the U-Mo particles and the Al matrix to grow U(Al, Si)3 and U3Si5 phases. Finally both coatings have shown excellent performances under thermal treatment by limiting drastically the U-Mo/Al interdiffusion. U(Al,Si)3 with two lattice parameters (4.16 Å and 4.21 Å), A distorted U3Si5 phase. Note that these phases were not present in the U-Mo(Si) powders. These phases are usually found in the Silicon rich diffusion layer (SiRDL) obtained in dispersed fuels (as-manufactured U-Mo/Al(Si) fuel plates [12,3] or annealed UMo(Si)/Al fuel rods [40]) as well as in diffusion couples (U-Mo/Al(Si7) [37-39] or U

  4. Numerical and experimental study of electron-beam coatings with modifying particles FeB and FeTi

    NASA Astrophysics Data System (ADS)

    Kryukova, Olga; Kolesnikova, Kseniya; Gal'chenko, Nina

    2016-07-01

    An experimental study of wear-resistant composite coatings based on titanium borides synthesized in the process of electron-beam welding of components thermo-reacting powders are composed of boron-containing mixture. A model of the process of electron beam coating with modifying particles of boron and titanium based on physical-chemical transformations is supposed. The dissolution process is described on the basis of formal kinetic approach. The result of numerical solution is the phase and chemical composition of the coating under nonequilibrium conditions, which is one of the important characteristics of the coating forming during electron beam processing. Qualitative agreement numerical calculations with experimental data was shown.

  5. Method for testing the strength and structural integrity of nuclear fuel particles

    DOEpatents

    Lessing, P.A.

    1995-10-17

    An accurate method for testing the strength of nuclear fuel particles is disclosed. Each particle includes an upper and lower portion, and is placed within a testing apparatus having upper and lower compression members. The upper compression member includes a depression therein which is circular and sized to receive only part of the upper portion of the particle. The lower compression member also includes a similar depression. The compression members are parallel to each other with the depressions therein being axially aligned. The fuel particle is then placed between the compression members and engaged within the depressions. The particle is then compressed between the compression members until it fractures. The amount of force needed to fracture the particle is thereafter recorded. This technique allows a broader distribution of forces and provides more accurate results compared with systems which distribute forces at singular points on the particle. 13 figs.

  6. Method for testing the strength and structural integrity of nuclear fuel particles

    DOEpatents

    Lessing, Paul A.

    1995-01-01

    An accurate method for testing the strength of nuclear fuel particles. Each particle includes an upper and lower portion, and is placed within a testing apparatus having upper and lower compression members. The upper compression member includes a depression therein which is circular and sized to receive only part of the upper portion of the particle. The lower compression member also includes a similar depression. The compression members are parallel to each other with the depressions therein being axially aligned. The fuel particle is then placed between the compression members and engaged within the depressions. The particle is then compressed between the compression members until it fractures. The amount of force needed to fracture the particle is thereafter recorded. This technique allows a broader distribution of forces and provides more accurate results compared with systems which distribute forces at singular points on the particle.

  7. Characteristics of SME biodiesel-fueled diesel particle emissions and the kinetics of oxidation.

    PubMed

    Jung, Heejung; Kittelson, David B; Zachariah, Michael R

    2006-08-15

    Biodiesel is one of the most promising alternative diesel fuels. As diesel emission regulations have become more stringent, the diesel particulate filter (DPF) has become an essential part of the aftertreatment system. Knowledge of kinetics of exhaust particle oxidation for alternative diesel fuels is useful in estimating the change in regeneration behavior of a DPF with such fuels. This study examines the characteristics of diesel particulate emissions as well as kinetics of particle oxidation using a 1996 John Deere T04045TF250 off-highway engine and 100% soy methyl ester (SME) biodiesel (B100) as fuel. Compared to standard D2 fuel, this B100 reduced particle size, number, and volume in the accumulation mode where most of the particle mass is found. At 75% load, number decreased by 38%, DGN decreased from 80 to 62 nm, and volume decreased by 82%. Part of this decrease is likely associated with the fact that the particles were more easily oxidized. Arrhenius parameters for the biodiesel fuel showed a 2-3times greater frequency factor and approximately 6 times higher oxidation rate compared to regular diesel fuel in the range of 700-825 degrees C. The faster oxidation kinetics should facilitate regeneration when used with a DPF.

  8. Coatings.

    ERIC Educational Resources Information Center

    Anderson, Dennis G.

    1989-01-01

    This review covers analytical techniques applicable to the examination of coatings, raw materials, and substrates upon which coatings are placed. Techniques include chemical and electrochemical methods, chromatography, spectroscopy, thermal analysis, microscopy, and miscellaneous techniques. (MVL)

  9. Impact of in situ polymer coating on particle dispersion into solid laser-generated nanocomposites.

    PubMed

    Wagener, Philipp; Brandes, Gudrun; Schwenke, Andreas; Barcikowski, Stephan

    2011-03-21

    The crucial step in the production of solid nanocomposites is the uniform embedding of nanoparticles into the polymer matrix, since the colloidal properties or specific physical properties are very sensitive to particle dispersion within the nanocomposite. Therefore, we studied a laser-based generation method of a nanocomposite which enables us to control the agglomeration of nanoparticles and to increase the single particle dispersion within polyurethane. For this purpose, we ablated targets of silver and copper inside a polymer-doped solution of tetrahydrofuran by a picosecond laser (using a pulse energy of 125 μJ at 33.3 kHz repetition rate) and hardened the resulting colloids into solid polymers. Electron microscopy of these nanocomposites revealed that primary particle size, agglomerate size and particle dispersion strongly depend on concentration of the polyurethane added before laser ablation. 0.3 wt% polyurethane is the optimal polymer concentration to produce nanocomposites with improved particle dispersion and adequate productivity. Lower polyurethane concentration results in agglomeration whereas higher concentration reduces the production rate significantly. The following evaporation step did not change the distribution of the nanocomposite inside the polyurethane matrix. Hence, the in situ coating of nanoparticles with polyurethane during laser ablation enables simple integration into the structural analogue polymer matrix without additives. Furthermore, it was possible to injection mold these in situ-stabilized nanocomposites without affecting particle dispersion. This clarifies that sufficient in situ stabilization during laser ablation in polymer solution is able to prevent agglomeration even in a hot polymer melt. PMID:21298127

  10. Microstructure and Wear Resistance of Plasma-Sprayed Molybdenum Coating Reinforced by MoSi2 Particles

    NASA Astrophysics Data System (ADS)

    Yan, Jianhui; He, Zheyu; Wang, Yi; Qiu, Jingwen; Wang, Yueming

    2016-10-01

    Mo coatings with or without incorporated MoSi2 were fabricated by atmospheric plasma spraying, and their microstructure, microhardness, bond strength, and wear resistance were compared. Two kinds of spray powder, i.e., pure Mo and a blend of Mo and MoSi2, were sprayed onto low-carbon steel. Microstructural analysis of the MoSi2-Mo coating showed MoSi2 homogeneously distributed in a Mo matrix. Addition of MoSi2 particles increased the microhardness of the as-sprayed Mo coating. The adhesion strength of the Mo coating was better than that of the MoSi2-Mo coating. Wear test results showed that the wear rate and friction coefficient of the two coatings increased with increasing load, and the friction coefficient of the MoSi2-Mo coating was lower than that of the Mo coating. The MoSi2-Mo composite coating exhibited better wear resistance than the Mo coating. The wear failure mechanisms of the two coatings were local plastic deformation, delamination, oxidation, and adhesion wear.

  11. Microstructure and Wear Resistance of Plasma-Sprayed Molybdenum Coating Reinforced by MoSi2 Particles

    NASA Astrophysics Data System (ADS)

    Yan, Jianhui; He, Zheyu; Wang, Yi; Qiu, Jingwen; Wang, Yueming

    2016-08-01

    Mo coatings with or without incorporated MoSi2 were fabricated by atmospheric plasma spraying, and their microstructure, microhardness, bond strength, and wear resistance were compared. Two kinds of spray powder, i.e., pure Mo and a blend of Mo and MoSi2, were sprayed onto low-carbon steel. Microstructural analysis of the MoSi2-Mo coating showed MoSi2 homogeneously distributed in a Mo matrix. Addition of MoSi2 particles increased the microhardness of the as-sprayed Mo coating. The adhesion strength of the Mo coating was better than that of the MoSi2-Mo coating. Wear test results showed that the wear rate and friction coefficient of the two coatings increased with increasing load, and the friction coefficient of the MoSi2-Mo coating was lower than that of the Mo coating. The MoSi2-Mo composite coating exhibited better wear resistance than the Mo coating. The wear failure mechanisms of the two coatings were local plastic deformation, delamination, oxidation, and adhesion wear.

  12. Fine and ultrafine particles generated during fluidized bed combustion of different solid fuels

    SciTech Connect

    Urciuolo, M.; Barone, A.; D'Alessio, A.; Chirone, R.

    2008-12-15

    The paper reports an experimental study carried out with a 110-mm ID fluidized bed combustor focused on the characterization of particulates formation/emission during combustion of coal and non-fossil solid fuels. Fuels included: a bituminous coal, a commercial predried and granulated sludge (GS), a refuse-derived fuel (RDF), and a biomass waste (pine seed shells). Stationary combustion experiments were carried out analyzing the fate of fuel ashes. Fly ashes collected at the combustor exhaust were characterized both in terms of particle size distribution and chemical composition, with respect to both trace and major elements. Tapping-Mode Atomic Force Microscopy (TM-AFM) technique and high-efficiency cyclone-type collector devices were used to characterize the size and morphology of the nanometric-and micronic-size fractions of fly ash emitted at the exhaust respectively. Results showed that during the combustion process: I) the size of the nanometric fraction ranges between 2 and 65 nm; ii) depending on the fuel tested, combustion-assisted attrition or the production of the primary ash particles originally present in the fuel particles, are responsible of fine particle generation. The amount in the fly ash of inorganic compounds is larger for the waste-derived fuels, reflecting the large inherent content of these compounds in the parent fuels.

  13. Microstructure and Sliding Wear Resistance of Laser Cladded WC/Ni Composite Coatings with Different Contents of WC Particle

    NASA Astrophysics Data System (ADS)

    Xu, J. S.; Zhang, X. C.; Xuan, F. Z.; Wang, Z. D.; Tu, S. T.

    2012-09-01

    The aim of this article was to address the effect of WC content on the microstructure, microhardness, and sliding wear resistance of laser cladded WC/Ni composite coatings. The content of WC particle in the feed powder varied in the range of 0-80 wt.%. Experimental results showed that the laser cladded coatings exhibited homogeneous microstructure without pores or cracks. By comparing with the 45# steel substrate, the microhardness of WC/Ni composite coatings was relatively high. The microhardness of coating increased with increasing the content of WC particles. The wear resistance of WC/Ni composite coatings was strongly dependent on the content of WC particle and their microstructure. When the WC content was lower than 40 wt.% in the feed powder, the wear rate of the coatings decreased with increasing WC content. The two-body abrasive wear was identified as the main wear mechanisms. For the coatings with WC content higher than 40 wt.% in the feed powder, their wear rate increased with increasing WC content. The three-body abrasive wear and fatigue wear were the main failures. The coating with 40 wt.% WC in the feed powder exhibited the best wear resistance.

  14. Scattering of Bessel beam by a conducting spheroidal particle with dielectric coating

    NASA Astrophysics Data System (ADS)

    Chen, Zhuyang; Han, Yiping; Cui, Zhiwei; Shi, Xiaowei

    2014-11-01

    Based on the generalized Lorenz-Mie theory, an analytic solution to the scattering of an on-axis incident Bessel beam by a conducting spheroidal particle with dielectric coating is presented by expanding the incident beam, scattered fields and the fields in the dielectric coating in terms of spheroidal vector wave functions. In particular, the incident beam is represented using the vector expressions of zero-order Bessel beam that well satisfy Maxwell's equations. The unknown expansion coefficients for the scattered fields are determined by a system of linear equations derived from the appropriate boundary conditions. Numerical results of the differential scattering cross section are evaluated, and the scattering characteristics are discussed in detail.

  15. Electrical four-point probing of spherical metallic thin films coated onto micron sized polymer particles

    NASA Astrophysics Data System (ADS)

    Pettersen, Sigurd R.; Stokkeland, August Emil; Kristiansen, Helge; Njagi, John; Redford, Keith; Goia, Dan V.; Zhang, Zhiliang; He, Jianying

    2016-07-01

    Micron-sized metal-coated polymer spheres are frequently used as filler particles in conductive composites for electronic interconnects. However, the intrinsic electrical resistivity of the spherical thin films has not been attainable due to deficiency in methods that eliminate the effect of contact resistance. In this work, a four-point probing method using vacuum compatible piezo-actuated micro robots was developed to directly investigate the electric properties of individual silver-coated spheres under real-time observation in a scanning electron microscope. Poly(methyl methacrylate) spheres with a diameter of 30 μm and four different film thicknesses (270 nm, 150 nm, 100 nm, and 60 nm) were investigated. By multiplying the experimental results with geometrical correction factors obtained using finite element models, the resistivities of the thin films were estimated for the four thicknesses. These were higher than the resistivity of bulk silver.

  16. Electricity Generation from Microbial Fuel Cell with Polypyrrole-Coated Carbon Nanofiber Composite.

    PubMed

    Roh, Sung-Hee

    2015-02-01

    Polyacrylonitrile (PAN) nanofibers, with and without embedded carbon nanotubes (CNTs) were fabricated by the electrospinning process. Polypyrrole (PPy) was coated on the activated PAN/CNT nanofiber by in-situ chemical polymerization in order to improve the electrochemical performance. The electrocatalytic behaviors of the PPy-PAN/CNT composite anode were investigated by means of cyclic voltammetry to evaluate as the anode for microbial fuel cells (MFCs) application. In comparison with unmodified carbon cloth (CC) anodes, PPy-PAN/CNT nanofiber composite showed the improvement of the maximum power density by 40%. The PPy-PAN/CNT nanofiber composite electrode therefore offers good prospects for application in MFCs. PMID:26353717

  17. Porous α-Al2O3 thermal barrier coatings with dispersed Pt particles prepared by cathode plasma electrolytic deposition

    NASA Astrophysics Data System (ADS)

    Wang, Peng; He, Ye-dong; Deng, Shun-jie; Zhang, Jin

    2016-01-01

    Porous α-Al2O3 thermal barrier coatings (TBCs) containing dispersed Pt particles were prepared by cathode plasma electrolytic deposition (CPED). The influence of the Pt particles on the microstructure of the coatings and the CPED process were studied. The prepared coatings were mainly composed of α-Al2O3. The average thickness of the coatings was approximately 100 μm. Such single-layer TBCs exhibited not only excellent high-temperature cyclic oxidation and spallation resistance, but also good thermal insulation properties. Porous α-Al2O3 TBCs inhibit further oxidation of alloy substrates because of their extremely low oxygen diffusion rate, provide good thermal insulation because of their porous structure, and exhibit excellent mechanical properties because of the toughening effect of the Pt particles and because of stress relaxation induced by deformation of the porous structure.

  18. Microstructure and Mechanical Properties of Cr-SiC Particles-Reinforced Fe-Based Alloy Coating

    NASA Astrophysics Data System (ADS)

    Wang, Fu-cheng; Du, Xiao-dong; Zhan, Ma-ji; Lang, Jing-wei; Zhou, Dan; Liu, Guang-fu; Shen, Jian

    2015-12-01

    In this study, SiC particles were first coated with Cr to form a layer that can protect the SiC particles from dissolution in the molten pool. Then, the Cr-SiC powder was injected into the tail of molten pool during plasma-transferred arc welding process (PTAW), where the temperature was relatively low, to prepare Cr-SiC particles reinforced Fe-based alloy coating. The microstructure and phase composition of the powder and surface coatings were analyzed, and the element distribution and hardness at the interfacial region were also evaluated. The protective layer consists of Cr3Si, Cr7C3, and Cr23C6, which play an important role in the microstructure and mechanical properties. The protective layer is dissolved in the molten pool forming a flocculent region and a transition region between the SiC particles and the matrix. The tribological performance of the coating was also assessed using a ring-block sliding wear tester with GGr15 grinding ring under 490 and 980 N load. Cr-SiC particles-reinforced coating has a lower wear rate than the unreinforced coating.

  19. Reactor Physics Behavior of Transuranic-Bearing TRISO-Particle Fuel in a Pressurized Water Reactor

    SciTech Connect

    Michael A. Pope; R. Sonat Sen; Abderrafi M. Ougouag; Gilles Youinou; Brian Boer

    2012-04-01

    Calculations have been performed to assess the neutronic behavior of pins of Fully-Ceramic Micro-encapsulated (FCM) fuel in otherwise-conventional Pressurized Water Reactor (PWR) fuel pins. The FCM fuel contains transuranic (TRU)-only oxide fuel in tri-isotropic (TRISO) particles with the TRU loading coming from the spent fuel of a conventional LWR after 5 years of cooling. Use of the TRISO particle fuel would provide an additional barrier to fission product release in the event of cladding failure. Depletion calculations were performed to evaluate reactivity-limited burnup of the TRU-only FCM fuel. These calculations showed that due to relatively little space available for fuel, the achievable burnup with these pins alone is quite small. Various reactivity parameters were also evaluated at each burnup step including moderator temperature coefficient (MTC), Doppler, and soluble boron worth. These were compared to reference UO{sub 2} and MOX unit cells. The TRU-only FCM fuel exhibits degraded MTC and Doppler coefficients relative to UO{sub 2} and MOX. Also, the reactivity effects of coolant voiding suggest that the behavior of this fuel would be similar to a MOX fuel of very high plutonium fraction, which are known to have positive void reactivity. In general, loading of TRU-only FCM fuel into an assembly without significant quantities of uranium presents challenges to the reactor design. However, if such FCM fuel pins are included in a heterogeneous assembly alongside LEU fuel pins, the overall reactivity behavior would be dominated by the uranium pins while attractive TRU destruction performance levels in the TRU-only FCM fuel pins is. From this work, it is concluded that use of heterogeneous assemblies such as these appears feasible from a preliminary reactor physics standpoint.

  20. Influence of injected silver content on synthesis of silver coated nickel particles by DC thermal plasma

    NASA Astrophysics Data System (ADS)

    Park, Si Taek; Kim, Tae-Hee; Park, Dong-Wha

    2016-06-01

    Silver nanoparticle-coated spherical nickel particles were prepared from a mixture of micro-sized silver and nickel as raw materials by DC thermal plasma treatment. The mixture of micro-sized silver and nickel powders was injected into the high-temperature region of an argon thermal plasma jet. Although the silver, with its very high thermal conductivity and relatively low boiling point, was thoroughly evaporated by this process, nickel was not evaporated perfectly because of its comparatively low thermal conductivity and high boiling point. The rough nickel powder was spheroidized as it melted. Finally, silver evaporated by the thermal plasma quickly condensed into nanoparticles on the surfaces of the micro-sized spherical nickel particles, aided by the sharp temperature gradient of the thermal plasma jet. With varying the ratios of silver to nickel feedstock from 1:10 to 5:1, the products synthesized in each condition were examined by XRD, XPS, FE-SEM, and FE-TEM. More silver nanoparticles were attached on the nickel by increasing the injected feedstock to 9.8 at% silver. Meanwhile, a decrease of silver in the products was observed when larger amounts of silver were introduced to the thermal plasma jet. The exposed silver components decreased with greater proportions of silver feedstock because of the metal's dendritic structure and the formation of silver-coated silver particles.

  1. Morphology of craters generated by hypervelocity impacts of micron-sized polypyrrole-coated olivine particles

    NASA Astrophysics Data System (ADS)

    Li, Y. W.; Bugiel, S.; Trieloff, M.; Hillier, Jon K.; Postberg, F.; Price, M. C.; Shu, A.; Fiege, K.; Fielding, L. A.; Armes, S. P.; Wu, Y. Y.; Grün, E.; Srama, R.

    2014-08-01

    To understand the process of cosmic dust particle impacts and translate crater morphology on smoothed metallic surfaces to dust properties, correct calibration of the experimental impact data is needed. This article presents the results of studies of crater morphology generated by impacts using micron-sized polypyrrole (PPy)-coated olivine particles. The particles were accelerated by an electrostatic dust accelerator to high speeds before they impacted onto polished aluminum targets. The projectile diameter and velocity ranges were 0.3-1.2 μm and 3-7 km s-1. After impact, stereopair images of the craters were taken using scanning electron microscope and 3-D reconstructions made to provide diameter and depth measurements. In this study, not just the dimensions of crater diameters and depths, but also the shape and dimensions of crater lips were analyzed. The craters created by the coated olivine projectiles are shown to have complicated shapes believed to be due to the nonspherical shape of the projectiles.

  2. Nuclear Energy Research Initiative Project No. 02 103 Innovative Low Cost Approaches to Automating QA/QC of Fuel Particle Production Using On Line Nondestructive Methods for Higher Reliability Final Project Report

    SciTech Connect

    Ahmed, Salahuddin; Batishko, Charles R.; Flake, Matthew; Good, Morris S.; Mathews, Royce; Morra, Marino; Panetta, Paul D.; Pardini, Allan F.; Sandness, Gerald A.; Tucker, Brian J.; Weier, Dennis R.; Hockey, Ronald L.; Gray, Joseph N.; Saurwein, John J.; Bond, Leonard J.; Lowden, Richard A.; Miller, James H.

    2006-02-28

    This Nuclear Energy Research Initiative (NERI) project was tasked with exploring, adapting, developing and demonstrating innovative nondestructive test methods to automate nuclear coated particle fuel inspection so as to provide the United States (US) with necessary improved and economical Quality Assurance and Control (QA/QC) that is needed for the fuels for several reactor concepts being proposed for both near term deployment [DOE NE & NERAC, 2001] and Generation IV nuclear systems. Replacing present day QA/QC methods, done manually and in many cases destructively, with higher speed automated nondestructive methods will make fuel production for advanced reactors economically feasible. For successful deployment of next generation reactors that employ particle fuels, or fuels in the form of pebbles based on particles, extremely large numbers of fuel particles will require inspection at throughput rates that do not significantly impact the proposed manufacturing processes. The focus of the project is nondestructive examination (NDE) technologies that can be automated for production speeds and make either: (I) On Process Measurements or (II) In Line Measurements. The inspection technologies selected will enable particle “quality” qualification as a particle or group of particles passes a sensor. A multiple attribute dependent signature will be measured and used for qualification or process control decisions. A primary task for achieving this objective is to establish standard signatures for both good/acceptable particles and the most problematic types of defects using several nondestructive methods.

  3. The characteristics of particle charging and deposition during powder coating processes with ultrafine powder

    NASA Astrophysics Data System (ADS)

    Meng, Xiangbo; Zhu, Jingxu Jesse; Zhang, Hui

    2009-03-01

    In a preceding work, the mechanisms of particle charging and deposition during powder coating processes were explored with coarse polyurethane powder. In this paper, the developed mechanisms were further examined with ultrafine polyurethane powder in order to meet the growing needs for ultrafine powder in finishing industries. This study first verified the previous findings in particle deposition, which account for a cone-shaped pattern formed by deposited particles on the substrate and a rise in particle accumulation in the fringe region. It was further demonstrated with ultrafine powder that, as disclosed by using coarse powder, the primary charging of in-flight particles competes with back corona in particle deposition processes, and the highest deposition efficiency is a compromise by balancing their effects. In comparison with coarse powder, ultrafine powder presents a faster reduction in the deposition rate with extended spraying duration, but shows some superiority in the uniformity of the deposited layer. In the case of charging characteristics of the deposited particles, it was further substantiated with ultrafine powder that the secondary charging mechanism takes predominance in determining the distribution of local charge-to-mass ratios. It was also disclosed that ultrafine powder shows a decreasing charge-to-mass ratio with increased charging voltage in the deposited layer, opposite to the increasing tendency of coarse powder. However, it was commonly demonstrated by both coarse and ultrafine powders that the charge-to-mass ratio of the deposited particles decreases with the extended spraying durations. In comparison, ultrafine powder is more likely to produce uniform charge-to-mass ratio distributions in the deposited layer, which contrast sharply with the ones associated with the coarse powder. In conclusion, it is believed that this study supplements the preceding study and is of great help in providing a comprehensive understanding of the mechanisms

  4. In-line spatial filtering velocimetry for particle size and film thickness determination in fluidized-bed pellet coating processes.

    PubMed

    Folttmann, Friederike; Knop, Klaus; Kleinebudde, Peter; Pein, Miriam

    2014-11-01

    A spatial filtering velocimetry (SFV) probe was applied to monitor the increase in particle size during pellet Wurster coating processes in-line. Accuracy of the in-line obtained pellet sizes was proven by at-line performed digital image analysis (DIA). Regarding particle growth, high conformity between both analytical methods (SFV/DIA) was examined for different coating processes. The influence of ring buffer size and the process of filling the buffer were investigated. With buffer sizes of 30,000-50,000 particles best results were obtained in this study. Investigated process parameters, such as inlet air volume and spray rate, had different effects on the impact of the SFV probe. While the particle rate (the number of particles detected by the SVF probe per second) was highly dependent on the inlet air volume, different spray rates of up to ・}1 g/min did not affect the detected particle growth. Artefacts and delays in SFV particle sizing appeared especially at the beginning of the coating processes. The slope of the particle growth during the final spraying period was therefore used to determine coating thickness.

  5. Proteins immobilization on the surface of modified plant viral particles coated with hydrophobic polycations.

    PubMed

    Nikitin, Nikolai A; Malinin, Andrei S; Trifonova, Ekaterina A; Rakhnyanskaya, Anna A; Yaroslavov, Aleksandr A; Karpova, Olga V; Atabekov, Joseph G

    2014-01-01

    Two hydrophobic cations based on poly-N-ethyl-vinylpyridine were used to produce biologically active complexes. The complexes obtained from tobacco mosaic virus (TMV) spherical particles (SPs), hydrophobic polycation, and a model protein were stable and did not aggregate in solution, particularly at high ionic strengths. The nucleic acid-free SPs were generated by thermal remodeling of the TMV (helical rod-shaped plant virus). The model protein preserved its antigenic activity in the ternary complex (SP-polycation-protein). Immobilization of proteins on the surface of SPs coated with hydrophobic cation is a promising approach to designing biologically active complexes used in bionanotechnologies. PMID:25121344

  6. Understanding the Adsorption Interface of Polyelectrolyte Coating on Redox Active Nanoparticles Using Soft Particle Electrokinetics and Its Biological Activity

    PubMed Central

    2015-01-01

    The application of cerium oxide nanoparticles (CNPs) for therapeutic purposes requires a stable dispersion of nanoparticles in a biological environment. The objective of this study is to tailor the properties of polyelectrolyte coated CNPs as a function of molecular weight to achieve a stable and catalytic active dispersion. The coating of CNPs with polyacrylic acid (PAA) has increased the dispersion stability of CNPs and enhanced the catalytic ability. The stability of PAA coating was analyzed using the change in the Gibbs free energy computed by the Langmuir adsorption model. The adsorption isotherms were determined using soft particle electrokinetics which overcomes the challenges presented by other techniques. The change in Gibbs free energy was highest for CNPs coated with PAA of 250 kg/mol indicating the most stable coating. The change in free energy for PAA of 100 kg/mol coated CNPs was 85% lower than the PAA of 250 kg/mol coated CNPs. This significant difference is caused by the strong adsorption of PAA of 100 kg/mol on CNPs. Catalytic activity of PAA-CNPs is assessed by the catalase enzymatic mimetic activity of nanoparticles. The catalase activity was higher for PAA coated CNPs as compared to bare CNPs which indicated preferential adsorption of hydrogen peroxide induced by coating. This indicates that the catalase activity is also affected by the structure of the coating layer. PMID:24673655

  7. Prediction of the micro-thermo-mechanical behaviors in dispersion nuclear fuel plates with heterogeneous particle distributions

    NASA Astrophysics Data System (ADS)

    Jiang, Yijie; Wang, Qiming; Cui, Yi; Huo, Yongzhong; Ding, Shurong; Zhang, Lin; Li, Yuanming

    2011-11-01

    Dispersion nuclear fuel elements have promising prospects to be used in advanced nuclear reactors and disposal of nuclear wastes. They consist of fuel meat and cladding, and the fuel meat is a kind of composite fuel in which the fuel particles are embedded in the non-fissile matrix. Prediction of the micro-thermo-mechanical behaviors in dispersion nuclear plates is of importance to their irradiation safety and optimal design. In this study, the heterogeneity of the fuel particles along the thickness direction in the fuel meat is considered. The 3D finite element models have been developed respectively for two cases: (1) variation of fuel particle-particle (PP) distances for the particles near the mid-plane of the fuel meat; (2) variation of the particle-cladding (PC) distances for the fuel particles near the interface between the fuel meat and the cladding. The respective finite strain constitutive relations are developed for the fuel particle, metal matrix and cladding. The developed virtual temperature method is used to simulate irradiation swelling of the fuel particles and irradiation growth of the metal cladding. Effects of the heterogeneous distributions of the fuel particles on the micro temperature fields and the micro stress-strain fields are investigated. The obtained results indicate that: (1) as a whole, the maximum Mises stress, equivalent plastic strain and first principal stress at the matrix between the two closest particles increase with decreasing the particle-particle (PP) distance; existence of large first principal stresses there may be the main factor that induces the matrix failure; (2) variation of the particle-cladding (PC) distance has remarkable effects on the interfacial normal stress and shear stress at the interface between the fuel meat and the cladding; the first principal stress at the cladding near the interface increases dramatically when the fuel particle is closer and closer to the cladding. Thus, the proper distance between the

  8. Abrasive wear by coal-fueled diesel engine and related particles

    SciTech Connect

    Ives, L.K. )

    1992-09-01

    The development of commercially viable diesel engines that operate directly on pulverized coal-fuels will require solution to the problem of severe abrasive wear. The purpose of the work described in this report was to investigate the nature of the abrasive wear problem. Analytical studies were carried out to determine the characteristics of the coal-fuel and associated combustion particles responsible for abrasion. Laboratory pinon-disk wear tests were conducted on oil-particle mixtures to determine the relationship between wear rate and a number of different particle characteristics, contact parameters, specimen materials properties, and other relevant variables.

  9. Online monitoring of particle mass flow rate in bottom spray fluid bed coating--development and application.

    PubMed

    Wang, Li Kun; Heng, Paul Wan Sia; Liew, Celine Valeria

    2010-08-16

    The primary purpose of this study is to develop a visiometric process analyzer for online monitoring of particle mass flow rate in the bottom spray fluid bed coating process. The secondary purpose is to investigate the influences of partition gap and air accelerator insert size on particle mass flow rate using the developed visiometric process analyzer. Particle movement in the region between the product chamber and partition column was captured using a high speed camera. Mean particle velocity and number of particles in the images were determined by particle image velocimetry and morphological image processing method respectively. Mass flow rate was calculated using particle velocity, number of particles in the images, particle density and size information. Particle velocity and number findings were validated using image tracking and manual particle counting techniques respectively. Validation experiments showed that the proposed method was accurate. Partition gap was found to influence particle mass flow rate by limiting the rate of solids flux into the partition column; the air accelerator insert was found to influence particle mass flow rate by a Venturi effect. Partition gap and air accelerator insert diameter needed to be adjusted accordingly in relation to the other variability sources and diameter of coating cores respectively. The potential, challenges and possible solutions of the proposed visiometric process analyzer were further discussed.

  10. TiN-based coatings on fuel cladding tubes for advanced nuclear reactors

    SciTech Connect

    Ickchan Kim; Fauzia Khatkhatay; Liang Jiao; Greg Swadener; James Cole; Jian Gan; Haiyan Wang

    2012-10-01

    Titanium nitride (TiN) thin films are coated on HT-9 and MA957 fuel cladding tubes and bars to explore their mechanical strength, thermal stability, diffusion barrier properties, and thermal conductivity properties. The ultimate goal is to implement TiN as an effective diffusion barrier to prevent the inter-diffusion between the nuclear fuel and the cladding material, and thus lead to a longer life time of the cladding tubes. Mechanical tests including hardness and scratch tests for the samples before and after thermal cycle tests show that the films have a high hardness of 28 GPa and excellent adhesion properties despite the thermal treatment. Thermal conductivity measurements demonstrate that the thin TiN films have very minimal impact on the overall thermal conductivity of the MA957 and HT9 substrates, i.e., the thermal conductivity of the uncoated HT-9 and MA957 substrates was 26.25 and 28.44 W m-1K-1 , and that of the coated ones was 26.21 and 28.38 W m-1K-1, respectively. A preliminary Ce diffusion test on the couple of Ce/TiN/HT-9 suggests that TiN has excellent material compatibility and good diffusion barrier properties.

  11. Chemical approaches to new coating and filler particles for paper technology

    NASA Astrophysics Data System (ADS)

    Partch, Richard

    1997-08-01

    Manufacturing technologies for making interactive paper have been steadily improving and have satisfied most present-day requirements of printers and other consumers. Features such as paper composition, color, texture, strength and chemical stability have been optimized through increased understanding of the chemical interactions between the raw material and additives. However, next generation higher-speed printing machines, the public's desire to read higher resolution print, and the need for better security papers are challenging chemists to develop new fillers for inks and paper. The latter are often dispersions of fine particles in a liquid or cellulose matrix. This presentation summarizes advances being made in the author's laboratory for preparing new and unique colloidal and coated particles having potential use by the paper and printing industry.

  12. Magnetorheological fluid based on submicrometric silica-coated magnetite particles under an oscillatory magnetic field

    NASA Astrophysics Data System (ADS)

    Agustín-Serrano, R.; Donado, F.; Rubio-Rosas, E.

    2013-06-01

    An experimental study conducted on the rheological properties of a magnetorheological fluid based on submicrometric silica-coated magnetite particles dispersed in silicone oil is presented. We investigated the rheological behaviour when the system is simultaneously exposed to a static field and a sinusoidal field used as a perturbation. The results show that the perturbation modifies the rheological behaviour of the system and can be used to control its physical properties; however, the changes that are induced are smaller than expected from previous results for the aggregation of particles under magnetic perturbations. We discussed this difference in terms of the ratio between the magnetic energy and the thermal energy. We observed that a threshold magnetic field exists; below it, the yield stress is practically zero, whereas above it, the yield stress grows quickly. We discuss this result in terms of a model based on chain length distribution.

  13. Synthesis of copper nanostructures on silica-based particles for antimicrobial organic coatings

    NASA Astrophysics Data System (ADS)

    Palza, Humberto; Delgado, Katherine; Curotto, Nicolás

    2015-12-01

    Sol-gel based silica nanoparticles of 100 nm were used to interact with copper ions from the dissolution of CuCl2 allowing the synthesis of paratacamite (Cu2(OH)3Cl) nanocrystals of around 20 nm. The method produced well dispersed copper nanostructures directly supported on the surface of the SiO2 particles and was generalized by using a natural zeolite microparticle as support with similar results. These hybrid Cu based nanoparticles released copper ions when immersed in water explaining their antimicrobial behavior against Escherichia coli and Staphylococcus aureus as measured by the minimum inhibitory and minimum bactericidal concentrations (MIC and MBC). Noteworthy, when these nanostructured particles were mixed with an organic coating the resulting film eliminated until a 99% of both bacteria at concentrations as low as 0.01 wt%.

  14. EXAFS study of metal-coated particles produced by ball milling

    SciTech Connect

    Heald, S.M.; Jayanetti, S.; Pandya, K.I.

    1992-01-01

    EXAFS measurements have been carried out on mixtures of Sa with Ge and Si, and Pt with SiO[sub 2] which have been ball milled for extended periods. In these systems the brittle component (Ge, Si, or SiO[sub 2]) is ground to nanocrystalline dimensions while the ductile metal is found to coat the outer surface the particles. Analysis shows that in the Sn-Ge and Sn-Si systems, mixing at the interface is found to form apparently cubic SnGe and SnSi alloys respectively. In the Pt-SiO[sub 2] system while no mixing is observed, the Pt is found to be highly dispersed on the surface of SiO[sub 2] particles.

  15. EXAFS study of metal-coated particles produced by ball milling

    SciTech Connect

    Heald, S.M.; Jayanetti, S.; Pandya, K.I.

    1992-11-01

    EXAFS measurements have been carried out on mixtures of Sa with Ge and Si, and Pt with SiO{sub 2} which have been ball milled for extended periods. In these systems the brittle component (Ge, Si, or SiO{sub 2}) is ground to nanocrystalline dimensions while the ductile metal is found to coat the outer surface the particles. Analysis shows that in the Sn-Ge and Sn-Si systems, mixing at the interface is found to form apparently cubic SnGe and SnSi alloys respectively. In the Pt-SiO{sub 2} system while no mixing is observed, the Pt is found to be highly dispersed on the surface of SiO{sub 2} particles.

  16. Investigations of submicron sized metal particles in glass coatings of lunar breccia 15286

    NASA Technical Reports Server (NTRS)

    Mehta, S.; Goldstein, J. I.; Friel, J. J.

    1979-01-01

    Almost all the submicron metal particles in the glass coating of breccia 15286 are rounded and contain two phases, metal and sulfide (FeS). The Ni content of the metal phase as determined by scanning transmission electron microscope X-ray analysis ranged from 9.4 to 15.5 wt %. The sulfide was nearly stoichiometric troilite containing up to 1.3 wt % Ni. The close chemical and microstructural similarities between the coarse (greater than 1-micron) and the submicron sized metal indicate a common origin probably as meteoritic debris. Metal-silicate melt experiments under controlled oxygen partial pressured indicate that the metal particles may have formed from a fine dispersion of immiscible metal-sulfide droplets into an impact-generated silicate melt.

  17. Preparation of lipase-coated, stabilized, hydrophobic magnetic particles for reversible conjugation of biomacromolecules.

    PubMed

    Marciello, Marzia; Bolivar, Juan M; Filice, Marco; Mateo, Cesar; Guisan, Jose M

    2013-03-11

    This Communication presents the development of a novel strategy for the easy conjugation of biomolecules to hydrophobic magnetic microparticles via reversible coating with previously functionalized lipase molecules. First, the ability of lipase to be strongly adsorbed onto hydrophobic surfaces was exploited for the stabilization of microparticles in aqueous medium by the creation of a hydrophilic surface. Second, the surface amino acids of lipase can be tailored to suit biomolecule conjugation. This approach has been demonstrated by amino-epoxy activation of lipase, enabling the conjugation of different biomolecules to the magnetic particle's surface. For example, it was possible to immobilize 70% of Escherichia coli proteins on the recovered particles. Furthermore, this strategy could be extended to other lipase chemical modification protocols, enabling fine control of biomolecule coupling. These conjugation techniques constitute a modular methodology that also permits the recycling of the magnetic carrier following use.

  18. Kaolinite particles as ice nuclei: learning from the use of different types of kaolinite and different coatings

    NASA Astrophysics Data System (ADS)

    Wex, Heike; DeMott, Paul; Tobo, Yutaka; Hartmann, Susan; Raddatz, Michael; Clauss, Tina; Niedermeier, Dennis; Stratmann, Frank

    2013-04-01

    The heterogeneous ice nucleation behaviour of particles from two different sources of kaolinite (one from Fluka, one from the Clay Mineral Society (CMS, KGa-1b)) was examined. For this, we used LACIS (Leipzig Aerosol Cloud Interaction Simulator) in its immersion freezing mode (Hartmann et al., 2011), in parallel to a CFDC (Continuous Flow Diffusion Chamber, Rogers et al., 2001; DeMott et al., 2010), which measured both, immersion freezing and deposition ice nucleation. Results reported here were collected for particles with a mobility diameter of 300nm. Pure kaolinite particles were examined, as well as kaolinite particles coated with thin coatings of either sulphuric acid, levoglucosan or succinic acid. In general, it was found that even the smallest amounts of any of the coatings strongly reduced deposition ice nucleation (Tobo et al., 2012). This was even true for coatings which did not produce a complete monolayer around the dust particles. In the immersion freezing mode, ice nucleation rates J(het) from both, LACIS and the CFDC measurements, agreed with each other. J(het) values for pure Fluka kaolinite particles were the same as those found for Fluka kaolinite particles coated with either levoglucosan or succinic acid, i.e. the coating did not have an influence on the particles ability to nucleate ice. It can be assumed that these two types of coating did not alter the ice active dust surface chemically, and that the comparably thin coatings were diluted enough in the droplets that were formed in LACIS and the CFDC prior to the immersion freezing so that freezing point depression did not play a major role. However, Fluka kaolinite particles which were coated with either pure sulphuric acid or which were first coated with the acid and then exposed to additional water vapour both showed a reduced ability to nucleate ice, compared to the pure particles in the immersion mode. Interestingly, for the CMS kaolinite particles, the ability to nucleate ice in the

  19. Abrasive wear by diesel engine coal-fuel and related particles

    SciTech Connect

    Ives, L.K.

    1994-09-01

    The purpose of the work summarized in this report was to obtain a basic understanding of the factors which are responsible for wear of the piston ring and cylinder wall surfaces in diesel engines utilizing coal-fuel. The approach included analytical studies using scanning electron microscopy and energy dispersive x-ray analyses to characterize coal-fuel and various combustion particles, and two different wear tests. The wear tests were a modified pin-on-disk test and a block-on-ring test capable of either unidirectional or reciprocating-rotational sliding. The wear tests in general were conducted with mixtures of the particles and lubricating oil. The particles studied included coal-fuel, particles resulting from the combustion of coal fuel, mineral matter extracted during the processing of coal, and several other common abrasive particle types among which quartz was the most extensively examined. The variables studied included those associated with the particles, such as particle type, size, and hardness; variables related to contact conditions and the surrounding environment; and variables related to the type and properties of the test specimen materials.

  20. Fuel Property, Emission Test, and Operability Results from a Fleet of Class 6 Vehicles Operating on Gas-to-Liquid Fuel and Catalyzed Diesel Particle Filters

    SciTech Connect

    Alleman, T. L.; Eudy, L.; Miyasato, M.; Oshinuga, A.; Allison, S.; Corcoran, T.; Chatterjee, S.; Jacobs, T.; Cherrillo, R. A.; Clark, R.; Virrels, I.; Nine, R.; Wayne, S.; Lansing, R.

    2005-11-01

    A fleet of six 2001 International Class 6 trucks operating in southern California was selected for an operability and emissions study using gas-to-liquid (GTL) fuel and catalyzed diesel particle filters (CDPF). Three vehicles were fueled with CARB specification diesel fuel and no emission control devices (current technology), and three vehicles were fueled with GTL fuel and retrofit with Johnson Matthey's CCRT diesel particulate filter. No engine modifications were made.

  1. Kinetics of fuel particle weathering and {sup 90}Sr mobility in the Chernobyl 30-km exclusion zone

    SciTech Connect

    Kashparov, V.A.; Zvarich, S.I.; Protsak, V.P.; Levchuk, S.E.; Oughton, D.H.

    1999-03-01

    Weathering of fuel particles and the subsequent leaching of radionuclides causes {sup 90}Sr mobility in Chernobyl soils to increase with time after disposition. Studies of {sup 90}Sr speciation in soils collected in 1995 and 1996 from the Chernobyl 30-km exclusion zone have been used to calculate rates of fuel particles dissolution under natural environmental conditions. Results show that the velocity of fuel particle dissolution is primarily dependent on the physico-chemical characteristics of the particles and partially dependent on soil acidity. Compared to other areas, the fuel particle dissolution rate is significantly lower in the contaminated areas to the west of the Chernobyl reactor where deposited particles were presumably not oxidized prior to release. The data have been used to derive mathematical models that describe the rate of radionuclide leaching from fuel particles in the exclusion zone and changes in soil-to-plant transfer as a function of particle type and soil pH.

  2. Mixing fuel particles for space combustion research using acoustics

    NASA Technical Reports Server (NTRS)

    Burns, Robert J.; Johnson, Jerome A.; Klimek, Robert B.

    1988-01-01

    Part of the microgravity science to be conducted aboard the Shuttle (STS) involves combustion using solids, particles, and liquid droplets. The central experimental facts needed for characterization of premixed quiescent particle cloud flames cannot be adequately established by normal gravity studies alone. The experimental results to date of acoustically mixing a prototypical particulate, lycopodium, in a 5 cm diameter by 75 cm long flame tube aboard a Learjet aircraft flying a 20 sec low gravity trajectory are described. Photographic and light detector instrumentation combine to measure and characterize particle cloud uniformity.

  3. Effective density and morphology of particles emitted from small-scale combustion of various wood fuels.

    PubMed

    Leskinen, Jani; Ihalainen, Mika; Torvela, Tiina; Kortelainen, Miika; Lamberg, Heikki; Tiitta, Petri; Jakobi, Gert; Grigonyte, Julija; Joutsensaari, Jorma; Sippula, Olli; Tissari, Jarkko; Virtanen, Annele; Zimmermann, Ralf; Jokiniemi, Jorma

    2014-11-18

    The effective density of fine particles emitted from small-scale wood combustion of various fuels were determined with a system consisting of an aerosol particle mass analyzer and a scanning mobility particle sizer (APM-SMPS). A novel sampling chamber was combined to the system to enable measurements of highly fluctuating combustion processes. In addition, mass-mobility exponents (relates mass and mobility size) were determined from the density data to describe the shape of the particles. Particle size, type of fuel, combustion phase, and combustion conditions were found to have an effect on the effective density and the particle shape. For example, steady combustion phase produced agglomerates with effective density of roughly 1 g cm(-3) for small particles, decreasing to 0.25 g cm(-3) for 400 nm particles. The effective density was higher for particles emitted from glowing embers phase (ca. 1-2 g cm(-3)), and a clear size dependency was not observed as the particles were nearly spherical in shape. This study shows that a single value cannot be used for the effective density of particles emitted from wood combustion.

  4. Effective density and morphology of particles emitted from small-scale combustion of various wood fuels.

    PubMed

    Leskinen, Jani; Ihalainen, Mika; Torvela, Tiina; Kortelainen, Miika; Lamberg, Heikki; Tiitta, Petri; Jakobi, Gert; Grigonyte, Julija; Joutsensaari, Jorma; Sippula, Olli; Tissari, Jarkko; Virtanen, Annele; Zimmermann, Ralf; Jokiniemi, Jorma

    2014-11-18

    The effective density of fine particles emitted from small-scale wood combustion of various fuels were determined with a system consisting of an aerosol particle mass analyzer and a scanning mobility particle sizer (APM-SMPS). A novel sampling chamber was combined to the system to enable measurements of highly fluctuating combustion processes. In addition, mass-mobility exponents (relates mass and mobility size) were determined from the density data to describe the shape of the particles. Particle size, type of fuel, combustion phase, and combustion conditions were found to have an effect on the effective density and the particle shape. For example, steady combustion phase produced agglomerates with effective density of roughly 1 g cm(-3) for small particles, decreasing to 0.25 g cm(-3) for 400 nm particles. The effective density was higher for particles emitted from glowing embers phase (ca. 1-2 g cm(-3)), and a clear size dependency was not observed as the particles were nearly spherical in shape. This study shows that a single value cannot be used for the effective density of particles emitted from wood combustion. PMID:25365741

  5. Engineering Multifunctional Living Paints: Thin, Convectively-Assembled Biocomposite Coatings of Live Cells and Colloidal Latex Particles Deposited by Continuous Convective-Sedimentation Assembly

    NASA Astrophysics Data System (ADS)

    Jenkins, Jessica Shawn

    Advanced composite materials could be revolutionized by the development of methods to incorporate living cells into functional materials and devices. This could be accomplished by continuously and rapidly depositing thin ordered arrays of adhesive colloidal latex particles and live cells that maintain stability and preserve microbial reactivity. Convective assembly is one method of rapidly assembling colloidal particles into thin (<10 microm thick), ordered films with engineered compositions, thicknesses, and particle packing that offer several advantages over thicker randomly ordered composites, including enhanced cell stability and increased reactivity through minimized diffusion resistance to nutrients and reduced light scattering. This method can be used to precisely deposit live bacteria, cyanobacteria, yeast, and algae into biocomposite coatings, forming reactive biosensors, photoabsorbers, or advanced biocatalysts. This dissertation developed new continuous deposition and coating characterization methods for fabricating and characterizing <10 microm thick colloid coatings---monodispersed latex particle or cell suspensions, bimodal blends of latex particles or live cells and microspheres, and trimodal formulations of biomodal latex and live cells on substrates such as aluminum foil, glass, porous Kraft paper, polyester, and polypropylene. Continuous convective-sedimentation assembly (CSA) is introduced to enable fabrication of larger surface area and long coatings by constantly feeding coating suspension to the meniscus, thus expanding the utility of convective assembly to deposit monolayer or very thin films or multi-layer coatings composed of thin layers on a large scale. Results show thin, tunable coatings can be fabricated from diverse coating suspensions and critical coating parameters that control thickness and structure. Particle size ratio and charge influence deposition, convective mixing or demixing and relative particle locations. Substrate

  6. Using CrAlN multilayer coatings to improve oxidation resistance of steel interconnects for solid oxide fuel cell stacks

    NASA Astrophysics Data System (ADS)

    Smith, R. J.; Tripp, C.; Knospe, A.; Ramana, C. V.; Kayani, A.; Gorokhovsky, Vladimir; Shutthanandan, V.; Gelles, D. S.

    2004-06-01

    The requirements of low-cost and high-temperature corrosion resistance for bipolar interconnect plates in solid oxide fuel cell stacks has directed attention to the use of metal plates with oxidation resistant coatings. The performance of steel plates with multilayer coatings, consisting of CrN for electrical conductivity and CrAlN for oxidation resistance, was investigated. The coatings were deposited using large area filtered arc deposition technology, and subsequently annealed in air for up to 25 hours at 800 °C. The composition, structure, and morphology of the coated plates were characterized using Rutherford backscattering, nuclear reaction analysis, atomic force microscopy, and transmission electron microscopy techniques. By altering the architecture of the layers within the coatings, the rate of oxidation was reduced by more than an order of magnitude. Electrical resistance was measured at room temperature.

  7. Using CrAIN Multilayer Coatings to Improve Oxidation Resistance of Steel Interconnects for Solid Oxide Fuel Cell Stacks

    SciTech Connect

    Smith, Richard J.; Tripp, C.; Knospe, Anders; Ramana, C. V.; Gorokhovsky, Vladimir I.; Shutthanandan, V.; Gelles, David S.

    2004-06-01

    The requirements of low cost and high-tempurature corrosion resistance for bipolar interconnect plates in solid oxide fuel cell stacks has directed attention to the use of metal plates with oxidation resistant coatings. We have investigatedt he performance of steel plates with multilayer coatings consisting of CrN for electrical conductivity and CrAIN for oxidation resistance. The coatings were deposited usin large area filterd arc deposition technolgy, and subsequently annealed in air for up to 25 hours at 800 degrees celsius. The composition, structer and morphology of the coated plates were characterized using RBS, nuclear reaction analysis, AFM and TEM techniques. By altering the architecture of the layers within the coatings, the rate of oxidation was reduced by more than an order of magnitute. Electrical resistance was measured at room temperature.

  8. Examination of laboratory-generated coated soot particles: An overview of the LACIS Experiment in November (LExNo) campaign

    NASA Astrophysics Data System (ADS)

    Stratmann, F.; Bilde, M.; Dusek, U.; Frank, G. P.; Hennig, T.; Henning, S.; Kiendler-Scharr, A.; Kiselev, A.; Kristensson, A.; Lieberwirth, I.; Mentel, T. F.; PöSchl, U.; Rose, D.; Schneider, J.; Snider, J. R.; Tillmann, R.; Walter, S.; Wex, H.

    2010-06-01

    In the suite of laboratory measurements described here and in companion articles we deal with the hygroscopic growth and activation behavior of coated soot particles synthesized to mimic those of an atmospheric aerosol originating from biomass combustion. The investigations were performed during the measurement campaign LACIS Experiment in November (LExNo) which took place at the Leipzig Aerosol Cloud Interaction Simulator (LACIS). The specific goals of this campaign were (1) to perform a critical supersaturation measurement intercomparison using data sets from three different cloud condensation nucleus (CCN) instruments (two static thermal gradient type, one stream-wise thermal gradient type) and LACIS, (2) to examine particle hygroscopic growth (hydrated particle size as function of relative humidity) for particle characteristics such as aerosol mass spectrometer (AMS) measured soluble mass and particle morphology, and (3) to relate critical supersaturations derived from both measurements of soluble mass and high-humidity tandem differential mobility analyzer (HH-TDMA) determined growth factors to critical supersaturations measured by means of the CCN instruments. This paper provides information on the particle synthesis techniques used during LExNo, an overview concerning the particle characterization measurements performed, and, by proving relations between measured composition, hygroscopic growth, and activation data, lay the foundations for the detailed investigations described in the companion studies. In the context of the present paper, excellent agreement of the critical supersaturations measured with three different CCN instruments and LACIS was observed. Furthermore, clear relations between coating masses determined with AMS and both hygroscopic growth factors at 98% RH and measured critical supersaturations could be seen. Also, a strong correlation between measured hygroscopic growth (growth factors at 98%) and measured critical supersaturation for all

  9. Adaptive neuro-fuzzy inference system (ANFIS) to predict CI engine parameters fueled with nano-particles additive to diesel fuel

    NASA Astrophysics Data System (ADS)

    Ghanbari, M.; Najafi, G.; Ghobadian, B.; Mamat, R.; Noor, M. M.; Moosavian, A.

    2015-12-01

    This paper studies the use of adaptive neuro-fuzzy inference system (ANFIS) to predict the performance parameters and exhaust emissions of a diesel engine operating on nanodiesel blended fuels. In order to predict the engine parameters, the whole experimental data were randomly divided into training and testing data. For ANFIS modelling, Gaussian curve membership function (gaussmf) and 200 training epochs (iteration) were found to be optimum choices for training process. The results demonstrate that ANFIS is capable of predicting the diesel engine performance and emissions. In the experimental step, Carbon nano tubes (CNT) (40, 80 and 120 ppm) and nano silver particles (40, 80 and 120 ppm) with nanostructure were prepared and added as additive to the diesel fuel. Six cylinders, four-stroke diesel engine was fuelled with these new blended fuels and operated at different engine speeds. Experimental test results indicated the fact that adding nano particles to diesel fuel, increased diesel engine power and torque output. For nano-diesel it was found that the brake specific fuel consumption (bsfc) was decreased compared to the net diesel fuel. The results proved that with increase of nano particles concentrations (from 40 ppm to 120 ppm) in diesel fuel, CO2 emission increased. CO emission in diesel fuel with nano-particles was lower significantly compared to pure diesel fuel. UHC emission with silver nano-diesel blended fuel decreased while with fuels that contains CNT nano particles increased. The trend of NOx emission was inverse compared to the UHC emission. With adding nano particles to the blended fuels, NOx increased compared to the net diesel fuel. The tests revealed that silver & CNT nano particles can be used as additive in diesel fuel to improve combustion of the fuel and reduce the exhaust emissions significantly.

  10. Size distribution of EC, OC and particle-phase PAHs emissions from a diesel engine fueled with three fuels.

    PubMed

    Lu, Tian; Huang, Zhen; Cheung, C S; Ma, Jing

    2012-11-01

    The size distribution of elemental carbon (EC), organic carbon (OC) and particle-phase PAHs emission from a direct injection diesel engine fueled with a waste cooking biodiesel, ultra low sulfur diesel (ULSD, 10-ppm-wt), and low sulfur diesel (LSD, 400-ppm-wt) were investigated experimentally. The emission factor of biodiesel EC is 90.6 mg/kh, which decreases by 60.3 and 71.7%, compared with ULSD and LSD respectively and the mass mean diameter (MMD) of EC was also decreased with the use of biodiesel. The effect of biodiesel on OC emission might depend on the engine operation condition, and the difference in OC size distribution is not that significant among the three fuels. For biodiesel, its brake specific emission of particle-phase PAHs is obviously smaller than that from the two diesel fuels, and the reduction effect appears in almost all size ranges. In terms of size distribution, the MMD of PAHs from biodiesel is larger than that from the two diesel fuels, which could be attributed to the more effective reduction on combustion derived PAHs in nuclei mode. The toxicity analysis indicates that biodiesel could reduce the total PAHs emissions, as well as the carcinogenic potency of particle-phase PAHs in almost all the size ranges.

  11. Specific Measurements of In-Flight Droplet and Particle Behavior and Coating Microstructure in Suspension and Solution Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Fauchais, P.; Vardelle, M.; Goutier, S.; Vardelle, A.

    2015-12-01

    The plasma spraying of suspensions of sub-micro- or nano-sized particles and of solutions of chemicals precursors produces finely structured coatings that have generally enhanced properties compared to conventional plasma-sprayed coatings. However, most techniques used in conventional plasma spraying are no more adapted to experimentally observe the behavior of the liquid feedstock in the plasma jet and investigate the effect of the operating conditions on liquid fragmentation in droplets, solid particles released by solvent evaporation or formed from the chemical precursors. Also, specific techniques have to be used to study the coating formation and characterize its microstructure. This paper aims to present the main techniques developed or adapted, up to now, to study the plasma-liquid feedstock interactions and characterize the coatings achieved by suspension and solution plasma spraying.

  12. Differential proteomic analysis of mouse macrophages exposed to adsorbate-loaded heavy fuel oil derived combustion particles using an automated sample-preparation workflow.

    PubMed

    Kanashova, Tamara; Popp, Oliver; Orasche, Jürgen; Karg, Erwin; Harndorf, Horst; Stengel, Benjamin; Sklorz, Martin; Streibel, Thorsten; Zimmermann, Ralf; Dittmar, Gunnar

    2015-08-01

    Ship diesel combustion particles are known to cause broad cytotoxic effects and thereby strongly impact human health. Particles from heavy fuel oil (HFO) operated ships are considered as particularly dangerous. However, little is known about the relevant components of the ship emission particles. In particular, it is interesting to know if the particle cores, consisting of soot and metal oxides, or the adsorbate layers, consisting of semi- and low-volatile organic compounds and salts, are more relevant. We therefore sought to relate the adsorbates and the core composition of HFO combustion particles to the early cellular responses, allowing for the development of measures that counteract their detrimental effects. Hence, the semi-volatile coating of HFO-operated ship diesel engine particles was removed by stepwise thermal stripping using different temperatures. RAW 264.7 macrophages were exposed to native and thermally stripped particles in submersed culture. Proteomic changes were monitored by two different quantitative mass spectrometry approaches, stable isotope labeling by amino acids in cell culture (SILAC) and dimethyl labeling. Our data revealed that cells reacted differently to native or stripped HFO combustion particles. Cells exposed to thermally stripped particles showed a very differential reaction with respect to the composition of the individual chemical load of the particle. The cellular reactions of the HFO particles included reaction to oxidative stress, reorganization of the cytoskeleton and changes in endocytosis. Cells exposed to the 280 °C treated particles showed an induction of RNA-related processes, a number of mitochondria-associated processes as well as DNA damage response, while the exposure to 580 °C treated HFO particles mainly induced the regulation of intracellular transport. In summary, our analysis based on a highly reproducible automated proteomic sample-preparation procedure shows a diverse cellular response, depending on the

  13. Surface characteristic of chemically converted graphene coated low carbon steel by electro spray coating method for polymer electrolyte membrane fuel cell bipolar plate.

    PubMed

    Kim, Jungsoo; Kim, Yang Do; Nam, Dae Geun

    2013-05-01

    Graphene was coated on low carbon steel (SS400) by electro spray coating method to improve its properties of corrosion resistance and contact resistance. Exfoliated graphite was made of the graphite by chemical treatment (Chemically Converted Graphene, CCG). CCG is distributed using dispersing agent, and low carbon steel was coated with diffuse graphene solution by electro spray coating method. The structure of the CCG was analyzed using XRD and the coating layer of surface was analyzed using SEM. Analysis showed that multi-layered graphite structure was destroyed and it was transformed in to fine layers graphene structure. And the result of SEM analysis on the surface and the cross section, graphene layer was uniformly formed with 3-5 microm thickness on the surface of substrate. Corrosion resistance test was applied in the corrosive solution which is similar to the polymer electrolyte membrane fuel cell (PEMFC) stack inside. And interfacial contact resistance (ICR) test was measured to simulate the internal operating conditions of PEMFC stack. As a result of measuring corrosion resistance and contact resistance, it could be confirmed that low carbon steel coated with CCG was revealed to be more effective in terms of its applicability as PEMFC bipolar plate. PMID:23858864

  14. Corrosion Resistance of Laser Produced in-situ Particle Reinforced Fe-matrix Composite Coating with High Nickel Content on Spheroidal Graphite Cast Iron

    NASA Astrophysics Data System (ADS)

    Qiwen, W.; Mingxing, M.; Cunyuan, P.; Xiaohui, Y.; Weiming, Z.

    Fe-matrix composite coatings reinforced by in-situ particles with high nickel content were produced on QT450-10 by laser alloying. Coatings with different microstructure proportions and particle distributions were obtained by the adjustment of the content of Ni, Ti and Zr in the alloying powder and the laser parameters. The influence of the content of Ni and the particle distribution on coating's corrosion resistance is studied, which is revealed by the electrochemical characteristics. The results indicate that the alloying coating with more content of nickel and less particles get corroded much harder with a higher corrosion rate.

  15. Single Particle Deformation and Analysis of Silica-Coated Gold Nanorods before and after Femtosecond Laser Pulse Excitation

    PubMed Central

    2016-01-01

    We performed single particle deformation experiments on silica-coated gold nanorods under femtosecond (fs) illumination. Changes in the particle shape were analyzed by electron microscopy and associated changes in the plasmon resonance by electron energy loss spectroscopy. Silica-coated rods were found to be more stable compared to uncoated rods but could still be deformed via an intermediate bullet-like shape for silica shell thicknesses of 14 nm. Changes in the size ratio of the rods after fs-illumination resulted in blue-shifting of the longitudinal plasmon resonances. Two-dimensional spatial mapping of the plasmon resonances revealed that the flat side of the bullet-like particles showed a less pronounced longitudinal plasmonic electric field enhancement. These findings were confirmed by finite-difference time-domain (FDTD) simulations. Furthermore, at higher laser fluences size reduction of the particles was found as well as for particles that were not completely deformed yet. PMID:26871607

  16. Single Particle Deformation and Analysis of Silica-Coated Gold Nanorods before and after Femtosecond Laser Pulse Excitation.

    PubMed

    Albrecht, Wiebke; Deng, Tian-Song; Goris, Bart; van Huis, Marijn A; Bals, Sara; van Blaaderen, Alfons

    2016-03-01

    We performed single particle deformation experiments on silica-coated gold nanorods under femtosecond (fs) illumination. Changes in the particle shape were analyzed by electron microscopy and associated changes in the plasmon resonance by electron energy loss spectroscopy. Silica-coated rods were found to be more stable compared to uncoated rods but could still be deformed via an intermediate bullet-like shape for silica shell thicknesses of 14 nm. Changes in the size ratio of the rods after fs-illumination resulted in blue-shifting of the longitudinal plasmon resonances. Two-dimensional spatial mapping of the plasmon resonances revealed that the flat side of the bullet-like particles showed a less pronounced longitudinal plasmonic electric field enhancement. These findings were confirmed by finite-difference time-domain (FDTD) simulations. Furthermore, at higher laser fluences size reduction of the particles was found as well as for particles that were not completely deformed yet.

  17. Utilization of calcium carbonate particles from eggshell waste as coating pigments for ink-jet printing paper.

    PubMed

    Yoo, Sukjoon; Hsieh, Jeffery S; Zou, Peter; Kokoszka, John

    2009-12-01

    The effective treatment and utilization of biowaste have been emphasized in our society for environmental and economic concerns. Recently, the eggshell waste in the poultry industry has been highlighted because of its reclamation potential. This study presents an economical treatment process to recover useful bioproducts from eggshell waste and their utilization in commercial products. We developed the dissolved air floatation (DAF) separation unit, which successfully recovered 96% of eggshell membrane and 99% of eggshell calcium carbonate (ECC) particles from eggshell waste within 2 h of operation. The recovered ECC particles were utilized as coating pigments for ink-jet printing paper and their impact on the ink density and paper gloss were investigated. The addition of the ECC particles as coating pigments enhances the optical density of cyan, magenta and yellow inks while decreasing the black ink density and the gloss of the coated paper.

  18. Ultraviolet and charged particle irradiation of proposed solar cell coverslide materials and conductive coatings for the Helios spacecraft

    NASA Technical Reports Server (NTRS)

    Fry, J.; Nicoletta, C. A.

    1972-01-01

    Coverslide materials consisting of Corning 7940 fused silica, multilayers of titanium and manganese oxides (blue reflector), and indium oxide (conductive-coating) were exposed to 16 UVSC up to 800 EUVSH in vacuum. Slight changes in optical transmittance and optical absorptance were found in the (200-360) millimicron regions of the fused silica and conductive coating respectively. Exposure to 4 KeV protons and 4.5 KeV electrons in vacuum, produced decreases of several percent in transmittance, (200-360) millimicron region in the fused silicas after total fluxes less or = 10 to the 14th power particles/sq cm. Sheet resistance of the conductive coating increased above 1.0 kilo-ohm/square after a total flux less or = 10 to the 14th power particles/sq cm. Solar cells with coverglasses utilizing the indium oxide conductive coating were exposed to 1 Mev electrons and 1 Mev protons in air and in vacuum. Total fluxes ranged from 10 to the 11th power particles/sq cm to 10 to the 15th power particle/sq cm. There was no appreciable degradation in the resistance of the conductive coating during or after these tests.

  19. Evaluation of gravimetric and volumetric dispensers of particles of nuclear material. [Accurate dispensing of fissile and fertile fuel into fuel rods

    SciTech Connect

    Bayne, C.K.; Angelini, P.

    1981-08-01

    Theoretical and experimental studies compared the abilities of volumetric and gravimetric dispensers to dispense accurately fissile and fertile fuel particles. Such devices are being developed for the fabrication of sphere-pac fuel rods for high-temperature gas-cooled light water and fast breeder reactors. The theoretical examination suggests that, although the fuel particles are dispensed more accurately by the gravimetric dispenser, the amount of nuclear material in the fuel particles dispensed by the two methods is not significantly different. The experimental results demonstrated that the volumetric dispenser can dispense both fuel particles and nuclear materials that meet standards for fabricating fuel rods. Performance of the more complex gravimetric dispenser was not significantly better than that of the simple yet accurate volumetric dispenser.

  20. Online single particle measurements of black carbon coatings, structure and optical properties

    NASA Astrophysics Data System (ADS)

    Allan, James; Liu, Dantong; Taylor, Jonathan; Flynn, Michael; Williams, Paul; Morgan, William; Whitehead, James; Alfarra, Rami; McFiggans, Gordon; Coe, Hugh

    2016-04-01

    The impacts of black carbon on meteorology and climate remain a major source of uncertainty, owing in part to the complex relationship between the bulk composition of the particulates and their optical properties. A particular complication stems from how light interacts with particles in response to the microphysical configuration and any 'coatings', i.e. non-black carbon material that is either co-emitted or subsequently obtained through atmospheric processing. This may cause the particle to more efficiently absorb or scatter light and may even change the sign of its radiative forcing potential. While much insight has been gained through measurements of bulk aerosol properties, either while suspended or after collection on a filter or impactor substrate, this does not provide a complete picture and thus may not adequately constrain the system. Here we present an overview of recent work to better constrain the properties of black carbon using online, in situ measurements of single particles, primarily using a Single Particle Soot Photometer (SP2). We have developed novel methods of inverting the data produced and combining the different metrics derived so as to give the most effective insights into black carbon sources, processes and properties. We have also used this measurement in conjunction with other instruments (sometimes in series) and used the data to challenge many commonly used models of optical properties such as core-shell Mie, Rayleigh-Debeye-Gans and effective medium. This work has been carried out in a variety of atmospheric environments and with laboratory-produced soots, e.g. from a diesel engine rig. Highlights include the finding that with real-world atmospheric aerosols, bulk optical measurements may be insufficient to derive brown carbon parameters without detailed morphological data. We also show that the enhancement of absorption for both ambient and laboratory generated particles only occurs after the coating mass fraction reaches a certain

  1. Monte Carlo simulation of light scattering from size distributed homogenous and coated spherical particles

    NASA Astrophysics Data System (ADS)

    Gogoi, Ankur

    Light scattering is a subject of intensive research at the present time in diverse fields of research namely, physics, astronomy, meteorology, biology, nanotechnology, etc. Observation and theoretical calculation of the absorption and scattering properties of particles, whose size ranges from micrometer to nanometer, are not only essential to deduce their physical properties but also capable of giving useful information for better understanding of radiation transfer through a medium containing such scatterer. In addition to such experimental and theoretical studies on light scattering by particulate matter several other groups have been extensively using Monte Carlo (MC) method to simulate light (photon) propagation in scattering media. Importantly such methods of simulating light scattering properties of artificial particles are proving to be a very useful tool in verifying the experimental observations with real samples as well as providing new clues to improve the accuracy of the existing theoretical models. In this contribution we report a MC method developed by implementing Mie theory to simulate the light scattering pattern from size distributed homogenous and coated spherical particles in single scattering regime. The computer program was written in ANSI C-language. The accuracy, efficiency and reliability of the MC method were validated by comparing the results generated by using the MC method with other benchmark theoretical results and experimental results with standard samples. Notably the MC method reported here is found to be stable even for very large spherical particles (size parameters > 1000) with large values of real (= 10) and imaginary part (= 10) of the refractive index. The promising field of application of the reported MC method will be in simulating the light (or electromagnetic) scattering properties of different types of planetary and interplanetary dust particles.

  2. Partitioning behavior of aromatic components in jet fuel into diverse membrane-coated fibers.

    PubMed

    Baynes, Ronald E; Xia, Xin-Rui; Barlow, Beth M; Riviere, Jim E

    2007-11-01

    Jet fuel components are known to partition into skin and produce occupational irritant contact dermatitis (OICD) and potentially adverse systemic effects. The purpose of this study was to determine how jet fuel components partition (1) from solvent mixtures into diverse membrane-coated fibers (MCFs) and (2) from biological media into MCFs to predict tissue distribution. Three diverse MCFs, polydimethylsiloxane (PDMS, lipophilic), polyacrylate (PA, polarizable), and carbowax (CAR, polar), were selected to simulate the physicochemical properties of skin in vivo. Following an appropriate equilibrium time between the MCF and dosing solutions, the MCF was injected directly into a gas chromatograph/mass spectrometer (GC-MS) to quantify the amount that partitioned into the membrane. Three vehicles (water, 50% ethanol-water, and albumin-containing media solution) were studied for selected jet fuel components. The more hydrophobic the component, the greater was the partitioning into the membranes across all MCF types, especially from water. The presence of ethanol as a surrogate solvent resulted in significantly reduced partitioning into the MCFs with discernible differences across the three fibers based on their chemistries. The presence of a plasma substitute (media) also reduced partitioning into the MCF, with the CAR MCF system being better correlated to the predicted partitioning of aromatic components into skin. This study demonstrated that a single or multiple set of MCF fibers may be used as a surrogate for octanol/water systems and skin to assess partitioning behavior of nine aromatic components frequently formulated with jet fuels. These diverse inert fibers were able to assess solute partitioning from a blood substitute such as media into a membrane possessing physicochemical properties similar to human skin. This information may be incorporated into physiologically based pharmacokinetic (PBPK) models to provide a more accurate assessment of tissue dosimetry of

  3. Nanostructured Indium Oxide Coated Silicon Nanowire Arrays: A Hybrid Photothermal/Photochemical Approach to Solar Fuels.

    PubMed

    Hoch, Laura B; O'Brien, Paul G; Jelle, Abdinoor; Sandhel, Amit; Perovic, Douglas D; Mims, Charles A; Ozin, Geoffrey A

    2016-09-27

    The field of solar fuels seeks to harness abundant solar energy by driving useful molecular transformations. Of particular interest is the photodriven conversion of greenhouse gas CO2 into carbon-based fuels and chemical feedstocks, with the ultimate goal of providing a sustainable alternative to traditional fossil fuels. Nonstoichiometric, hydroxylated indium oxide nanoparticles, denoted In2O3-x(OH)y, have been shown to function as active photocatalysts for CO2 reduction to CO via the reverse water gas shift reaction under simulated solar irradiation. However, the relatively wide band gap (2.9 eV) of indium oxide restricts the portion of the solar irradiance that can be utilized to ∼9%, and the elevated reaction temperatures required (150-190 °C) reduce the overall energy efficiency of the process. Herein we report a hybrid catalyst consisting of a vertically aligned silicon nanowire (SiNW) support evenly coated by In2O3-x(OH)y nanoparticles that utilizes the vast majority of the solar irradiance to simultaneously produce both the photogenerated charge carriers and heat required to reduce CO2 to CO at a rate of 22.0 μmol·gcat(-1)·h(-1). Further, improved light harvesting efficiency of the In2O3-x(OH)y/SiNW films due to minimized reflection losses and enhanced light trapping within the SiNW support results in a ∼6-fold increase in photocatalytic conversion rates over identical In2O3-x(OH)y films prepared on roughened glass substrates. The ability of this In2O3-x(OH)y/SiNW hybrid catalyst to perform the dual function of utilizing both light and heat energy provided by the broad-band solar irradiance to drive CO2 reduction reactions represents a general advance that is applicable to a wide range of catalysts in the field of solar fuels. PMID:27598429

  4. Nanostructured Indium Oxide Coated Silicon Nanowire Arrays: A Hybrid Photothermal/Photochemical Approach to Solar Fuels.

    PubMed

    Hoch, Laura B; O'Brien, Paul G; Jelle, Abdinoor; Sandhel, Amit; Perovic, Douglas D; Mims, Charles A; Ozin, Geoffrey A

    2016-09-27

    The field of solar fuels seeks to harness abundant solar energy by driving useful molecular transformations. Of particular interest is the photodriven conversion of greenhouse gas CO2 into carbon-based fuels and chemical feedstocks, with the ultimate goal of providing a sustainable alternative to traditional fossil fuels. Nonstoichiometric, hydroxylated indium oxide nanoparticles, denoted In2O3-x(OH)y, have been shown to function as active photocatalysts for CO2 reduction to CO via the reverse water gas shift reaction under simulated solar irradiation. However, the relatively wide band gap (2.9 eV) of indium oxide restricts the portion of the solar irradiance that can be utilized to ∼9%, and the elevated reaction temperatures required (150-190 °C) reduce the overall energy efficiency of the process. Herein we report a hybrid catalyst consisting of a vertically aligned silicon nanowire (SiNW) support evenly coated by In2O3-x(OH)y nanoparticles that utilizes the vast majority of the solar irradiance to simultaneously produce both the photogenerated charge carriers and heat required to reduce CO2 to CO at a rate of 22.0 μmol·gcat(-1)·h(-1). Further, improved light harvesting efficiency of the In2O3-x(OH)y/SiNW films due to minimized reflection losses and enhanced light trapping within the SiNW support results in a ∼6-fold increase in photocatalytic conversion rates over identical In2O3-x(OH)y films prepared on roughened glass substrates. The ability of this In2O3-x(OH)y/SiNW hybrid catalyst to perform the dual function of utilizing both light and heat energy provided by the broad-band solar irradiance to drive CO2 reduction reactions represents a general advance that is applicable to a wide range of catalysts in the field of solar fuels.

  5. Development of wear resistant nanostructured duplex coatings by high velocity oxy-fuel process for use in oil sands industry.

    PubMed

    Saha, Gobinda C; Khan, Tahir I; Glenesk, Larry B

    2009-07-01

    Oil sands deposits in Northern Alberta, Canada represent a wealth of resources attracting huge capital investment and significant research focus in recent years. As of 2005, crude oil production from the current oil sands operators accounted for 50% of Canada's domestic production. Alberta's oil sands deposits contain approximately 1.7 trillion barrels of bitumen, of which over 175 billion are recoverable with current technology, and 315 billion barrels are ultimately recoverable with technological advances. A major problem of operating machinery and equipment in the oil sands is the unpredictable failure from operating in this highly aggressive environment. One of the significant causes of that problem is premature material wear. An approach to minimize this wear is the use of protective coatings and, in particular, a cermet thin coating. A high level of coating homogeneity is critical for components such as bucketwheels, draglines, conveyors, shovels, heavyhauler trucks etc. that are subjected to severe degradation through abrasive wear. The identification, development and application of optimum wear solutions for these components pose an ongoing challenge. Nanostructured cermet coatings have shown the best results of achieving the degree of homogeneity required for these applications. In this study, WC-17Co cermet powder with nanocrystalline WC core encapsulated with 'duplex' Co layer was used to obtain a nanostructured coating. To apply this coating, high velocity oxy-fuel (HVOF) thermal spraying technique was used, as it is known for producing wear-resistant coatings superior to those obtained from plasma-based techniques. Mechanical, sliding wear and microstructural behavior of the coating was compared with those of the microstructured coating obtained from spraying WC-10Co-4Cr cermet powder by HVOF technique. Results from the nanostructured coating, among others, showed an average of 25% increase in microhardness, 30% increase in sliding wear resistance and

  6. Miniaturized ascorbic acid fuel cells with flexible electrodes made of graphene-coated carbon fiber cloth

    NASA Astrophysics Data System (ADS)

    Hoshi, Kazuki; Muramatsu, Kazuo; Sumi, Hisato; Nishioka, Yasushiro

    2016-04-01

    Ascorbic acid (AA) is a biologically friendly compound and exists in many products such as sports drinks, fruit, and even in human blood. Thus, a miniaturized and flexible ascorbic acid fuel cell (AAFC) is expected be a power source for portable or implantable electric devices. In this study, we fabricated an AAFC with anode and cathode dimensions of 3 × 10 mm2 made of a graphene-coated carbon fiber cloth (GCFC) and found that GCFC electrodes significantly improve the power generated by the AAFC. This is because the GCFC has more than two times the effective surface area of a conventional carbon fiber cloth and it can contain more enzymes. The power density of the AAFC in a phosphate buffer solution containing 100 mM AA at room temperature was 34.1 µW/cm2 at 0.46 V. Technical issues in applying the AAFC to portable devices are also discussed.

  7. Preparation of ZrC nano-particles reinforced amorphous carbon composite coating by atmospheric pressure chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Sun, W.; Xiong, X.; Huang, B. Y.; Li, G. D.; Zhang, H. B.; Xiao, P.; Chen, Z. K.; Zheng, X. L.

    2009-05-01

    To eliminate cracks caused by thermal expansion mismatch between ZrC coating and carbon-carbon composites, a kind of ZrC/C composite coating was designed as an interlayer. The atmospheric pressure chemical vapor deposition was used as a method to achieve co-deposition of ZrC and C from ZrCl 4-C 3H 6-H 2-Ar source. Zirconium tetrachloride (ZrCl 4) powder carrier was especially made to control accurately the flow rate. The microstructure of ZrC/C composite coating was studied using analytical techniques. ZrC/C coating shows same morphology as pyrolytic carbon. Transmission electron microscopy (TEM) shows ZrC grains with size of 10-50 nm embed in turbostratic carbon. The formation mechanism is that the growth of ZrC crystals was inhibited by surrounding pyrolytic carbon and kept as nano-particles. Fracture morphologies imply good combination between coating and substrate. The ZrC crystals have stoichiometric proportion near 1, with good crystalline but no clear preferred orientation while pyrolytic carbon is amorphous. The heating-up oxidation of ZrC/C coating shows 11.58 wt.% loss. It can be calculated that the coating consists of 74.04 wt.% ZrC and 25.96 wt.% pyrolytic carbon. The average density of the composite coating is 5.892 g/cm 3 by Archimedes' principle.

  8. Selective catalytic reduction operation with heavy fuel oil: NOx, NH3, and particle emissions.

    PubMed

    Lehtoranta, Kati; Vesala, Hannu; Koponen, Päivi; Korhonen, Satu

    2015-04-01

    To meet stringent NOx emission limits, selective catalytic reduction (SCR) is increasingly utilized in ships, likely also in combination with low-priced higher sulfur level fuels. In this study, the performance of SCR was studied by utilizing NOx, NH3, and particle measurements. Urea decomposition was studied with ammonia and isocyanic acid measurements and was found to be more effective with heavy fuel oil (HFO) than with light fuel oil. This is suggested to be explained by the metals found in HFO contributing to metal oxide particles catalyzing the hydrolysis reaction prior to SCR. At the exhaust temperature of 340 °C NOx reduction was 85-90%, while at lower temperatures the efficiency decreased. By increasing the catalyst loading, the low temperature behavior of the SCR was enhanced. The drawback of this, however, was the tendency of particle emissions (sulfate) to increase at higher temperatures with higher loaded catalysts. The particle size distribution results showed high amounts of nanoparticles (in 25-30 nm size), the formation of which SCR either increased or decreased. The findings of this work provide a better understanding of the usage of SCR in combination with a higher sulfur level fuel and also of ship particle emissions, which are a growing concern.

  9. The impact of fuel particle size distribution on neutron transport in stochastic media

    SciTech Connect

    Liang, C.; Pavlou, A. T.; Ji, W.

    2013-07-01

    This paper presents a study of the particle size distribution impact on neutron transport in three-dimensional stochastic media. An eigenvalue problem is simulated in a cylindrical container consisting of fissile fuel particles with five different size distributions: constant, uniform, power, exponential and Gaussian. We construct 15 cases by altering the fissile particle volume packing fraction and its optical thickness, but keeping the mean chord length of the spherical fuel particle the same at different size distributions. The tallied effective multiplication factor (k{sub eff}) and flux distribution along axial and radial directions are compared between different size distributions. At low packing fraction and low optical thickness, the size distribution has a significant impact on radiation transport in stochastic media, which can cause as high as {approx}270 pcm difference in k{sub eff} value and {approx}2.6% relative error difference in peak flux. As the packing fraction and optical thickness increase, the impact gradually dissipates. (authors)

  10. Nanostructure of Metallic Particles in Light Water Reactor Used Nuclear Fuel

    SciTech Connect

    Buck, Edgar C.; Mausolf, Edward J.; Mcnamara, Bruce K.; Soderquist, Chuck Z.; Schwantes, Jon M.

    2015-03-11

    The extraordinary nano-structure of metallic particles in light water reactor fuels points to possible high reactivity through increased surface area and a high concentration of high energy defect sites. We have analyzed the metallic epsilon particles from a high burn-up fuel from a boiling water reactor using transmission electron microscopy and have observed a much finer nanostructure in these particles than has been reported previously. The individual round particles that varying in size between ~20 and ~50 nm appear to consist of individual crystallites on the order of 2-3 nm in diameter. It is likely that in-reactor irradiation induce displacement cascades results in the formation of the nano-structure. The composition of these metallic phases is variable yet the structure of the material is consistent with the hexagonal close packed structure of epsilon-ruthenium. These findings suggest that unusual catalytic behavior of these materials might be expected, particularly under accident conditions.

  11. Continuous synthesis of polymer-coated drug particles by porous hollow fiber membrane-based antisolvent crystallization.

    PubMed

    Chen, Dengyue; Singh, Dhananjay; Sirkar, Kamalesh K; Pfeffer, Robert

    2015-01-01

    Using porous hollow fiber membranes, this study illustrates a novel technique to continuously synthesize polymer-coated drug crystals by antisolvent crystallization. The synthesized polymer-coated drug crystals involve crystals of the drug Griseofulvin (GF) coated by a thin layer of the polymer Eudragit RL100. The process feed, an acetone solution of the drug GF containing the dissolved polymer, was passed through the shell side of a membrane module containing many porous hollow fibers of Nylon-6. Through the lumen of the hollow fibers, the antisolvent water was passed at a higher pressure to inject water jets through every pore in the fiber wall into the shell-side acetone feed solution, creating an extremely high level of supersaturation and immediate crystallization. It appears that the GF crystals are formed first and serve as nuclei for the precipitation of the polymer Eudragit, which forms a thin coating around the GF crystals. The polymer-coated drug crystals were collected by a filtration device at the shell-side outlet of the membrane module, and the surface morphology, particle size distribution, and the polymer coating thickness were then characterized by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), laser diffraction spectroscopy (LDS), and thermogravimetric analysis (TGA). To study the properties of the coated drug crystals, X-ray diffraction (XRD), Raman spectroscopy, and dissolution tests were implemented. These results indicate that a polymer-coated, free-flowing product was successfully developed under appropriate conditions in this novel porous hollow fiber antisolvent crystallization (PHFAC) method. The coated drug particles can be potentially used for controlled release. The molecular and the crystal structures of GF were not affected by the PHFAC method, which may be easily scaled up.

  12. Effects of Rhamnolipid and Carboxymethylcellulose Coatings on Reactivity of Palladium-Doped Nanoscale Zerovalent Iron Particles.

    PubMed

    Bhattacharjee, Sourjya; Basnet, Mohan; Tufenkji, Nathalie; Ghoshal, Subhasis

    2016-02-16

    Nanoscale zerovalent iron (NZVI) particles are often coated with polymeric surface modifiers for improved colloidal stability and transport during remediation of contaminated aquifers. Doping the NZVI surface with palladium (Pd-NZVI) increases its reactivity to pollutants such as trichloroethylene (TCE). In this study, we investigate the effects of coating Pd-NZVI with two surface modifiers of very different molecular size: rhamnolipid (RL, anionic biosurfactant, M.W. 600 g mol(-1)) and carboxymethylcellulose (CMC, anionic polyelectrolyte, M.W. 700 000 g mol(-1)) on TCE degradation. RL loadings of 13-133 mg TOC/g NZVI inhibited deposition of Pd in a concentration-dependent manner, thus limiting the number of available Pd sites and decreasing the TCE degradation reaction rate constant from 0.191 h(-1) to 0.027 h(-1). Furthermore, the presence of RL in solution had an additional inhibitory effect on the reactivity of Pd-NZVI by interacting with the exposed Pd deposits after they were formed. In contrast, CMC had no effect on reactivity at loadings up to 167 mg TOC/g NZVI. There was a lack of correlation between Pd-NZVI aggregate sizes and TCE reaction rates, and is explained by cryo-transmission electron microscopy images that show open, porous aggregate structures where TCE would be able to easily access Pd sites. PMID:26745244

  13. Magnetic heating by silica-coated Co-Zn ferrite particles

    NASA Astrophysics Data System (ADS)

    Veverka, M.; Závěta, K.; Kaman, O.; Veverka, P.; Knížek, K.; Pollert, E.; Burian, M.; Kašpar, P.

    2014-02-01

    This study is aimed at the preparation of silica-coated nanoparticles of cobalt-zinc ferrite and their heating properties with respect to potential application in magnetic fluid hyperthermia. The magnetic cores of Co0.4Zn0.6Fe2O4+γ possessing two different sizes were prepared by the coprecipitation method followed by annealing and mechanical treatment. The subsequent encapsulation of the samples by silica led to colloidally stable suspensions in water. The single phase character of the cores was confirmed by x-ray powder diffraction while detailed studies of the coated products by transmission electron microscopy and x-ray photoelectron spectroscopy showed that the silica shell had a thickness of at least 5 nm. The dc magnetic measurements were employed in order to determine the concentrations of magnetic particles in suspensions and to analyse the distribution of blocking temperatures. The heating efficiency of the nanoparticles was studied simultaneously by means of magnetic and calorimetric measurements in various ac fields. Specifically, the magnetic losses were calculated from the ac hysteresis loops while the heating effect of the nanoparticles was determined by measuring the time dependence of the temperature of their suspensions. The evaluation of the heating power from the latter experiments was supplemented by deriving the corrections for non-adiabatic properties of the calorimeter. More accurate results enabled detailed analysis and comparison with data published for other heating agents.

  14. Nanostructured core-shell Ni deposition on SiC particles by alkaline electroless coating

    NASA Astrophysics Data System (ADS)

    Uysal, M.; Karslioğlu, R.; Alp, A.; Akbulut, H.

    2011-10-01

    In this study, core-shell nanostructured nickel formation on silicon carbide (SiC) ceramic powders was achieved through the electroless deposition method using alkaline solutions. To produce a nano core-shell Ni deposition on the SiC surfaces, process parameters such as pH values, the type of reducer material, deposition temperature, stirring rate and activation procedure among others were determined. Full coverage of core-shell nickel structures on SiC surfaces was achieved with a grain size of between 100 and 300 nm, which was approximately the same deposition thickness on the SiC surfaces. The surface morphology of the coated SiC particles showed a homogenous distribution of nanostructured nickel grains characterized by scanning electron microscopy and X-ray diffraction techniques. The nanostructures of the crystalline Ni coatings were observed to be attractive for achieving both good bonding and dense structure. The thin core shell-structure of Ni on the SiC surfaces was assessed as a beneficial reinforcement for possible metal matrix composite manufacturing.

  15. Environmental degradation of oxidation resistant and thermal barrier coatings for fuel-flexible gas turbine applications

    NASA Astrophysics Data System (ADS)

    Mohan, Prabhakar

    The development of thermal barrier coatings (TBCs) has been undoubtedly the most critical advancement in materials technology for modern gas turbine engines. TBCs are widely used in gas turbine engines for both power-generation and propulsion applications. Metallic oxidation-resistant coatings (ORCs) are also widely employed as a stand-alone protective coating or bond coat for TBCs in many high-temperature applications. Among the widely studied durability issues in these high-temperature protective coatings, one critical challenge that received greater attention in recent years is their resistance to high-temperature degradation due to corrosive deposits arising from fuel impurities and CMAS (calcium-magnesium-alumino-silicate) sand deposits from air ingestion. The presence of vanadium, sulfur, phosphorus, sodium and calcium impurities in alternative fuels warrants a clear understanding of high-temperature materials degradation for the development of fuel-flexible gas turbine engines. Degradation due to CMAS is a critical problem for gas turbine components operating in a dust-laden environment. In this study, high-temperature degradation due to aggressive deposits such as V2O5, P2O 5, Na2SO4, NaVO3, CaSO4 and a laboratory-synthesized CMAS sand for free-standing air plasma sprayed (APS) yttria stabilized zirconia (YSZ), the topcoat of the TBC system, and APS CoNiCrAlY, the bond coat of the TBC system or a stand-alone ORC, is examined. Phase transformations and microstructural development were examined by using x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. This study demonstrated that the V2O5 melt degrades the APS YSZ through the formation of ZrV2O7 and YVO 4 at temperatures below 747°C and above 747°C, respectively. Formation of YVO4 leads to the depletion of the Y2O 3 stabilizer and the deleterious transformation of the YSZ to the monoclinic ZrO2 phase. The investigation on the YSZ degradation by Na 2SO4 and a Na2SO4 + V2

  16. Corrosion resistance of enamel coating modified by calcium silicate and sand particle for steel reinforcement in concrete

    NASA Astrophysics Data System (ADS)

    Tang, Fujian

    Porcelain enamel has stable chemical property in harsh environments such as high temperature, acid and alkaline, and it can also chemically react with substrate reinforcing steel resulting in improved adherence strength. In this study, the corrosion resistances of enamel coating modified by calcium silicate and sand particles, which are designed for improved bond strength with surrounding concrete, were investigated in 3.5 wt% NaCl solution. It consists of two papers that describe the results of the study. The first paper investigates the corrosion behavior of enamel coating modified by calcium silicate applied to reinforcing steel bar in 3.5 wt% NaCl solution by OCP, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The coatings include a pure enamel, a mixed enamel that consists of 50% pure enamel and 50% calcium silicate by weight, and a double enamel that has an inner pure enamel layer and an outer mixed enamel layer. Electrochemical tests demonstrates that both pure and double enamel coatings can significantly improve corrosion resistance, while the mixed enamel coating offers very little protection due to connected channels. The second paper is focused on the electrochemical characteristics of enamel coating modified by sand particle applied to reinforcing steel bar in 3.5 wt% NaCl solution by EIS. Six percentages by weight are considered including 5%, 10%, 20%, 30%, 50%, and 70%. Results reveal that addition of sand particle does not affect its corrosion resistance significantly. Most of the sand particles can wet very well with enamel body, while some have a weak zone which is induced during the cooling stage due to different coefficient of thermal expansion. Therefore, quality control of sand particle is the key factor to improve its corrosion resistance.

  17. Improving Formate and Methanol Fuels: Catalytic Activity of Single Pd Coated Carbon Nanotubes

    PubMed Central

    2016-01-01

    The oxidations of formate and methanol on nitrogen-doped carbon nanotubes decorated with palladium nanoparticles were studied at both the single-nanotube and ensemble levels. Significant voltammetric differences were seen. Pd oxide formation as a competitive reaction with formate or methanol oxidation is significantly inhibited at high overpotentials under the high mass transport conditions associated with single-particle materials in comparison with that seen with ensembles, where slower diffusion prevails. Higher electro-oxidation efficiency for the organic fuels is achieved. PMID:27761299

  18. Rheological properties of magnetorheological suspensions based on core-shell structured polyaniline-coated carbonyl iron particles

    NASA Astrophysics Data System (ADS)

    Sedlačík, M.; Pavlínek, V.; Sáha, P.; Švrčinová, P.; Filip, P.; Stejskal, J.

    2010-11-01

    The sedimentation caused by the high density of suspended particles used in magnetorheological fluids is a significant obstacle for their wider application. In the present paper, core-shell structured carbonyl iron-polyaniline particles in silicone oil were used as a magnetorheological suspension with enhanced dispersion stability. Bare carbonyl iron particles were suspended in silicone oil to create model magnetorheological suspensions of different loading. For a magnetorheological suspension of polyaniline-coated particles the results show a decrease in the base viscosity. Moreover, the polyaniline coating has a negligible influence on the MR properties under an external magnetic field B. The change in the viscoelastic properties of magnetorheological suspensions in the small-strain oscillatory shear flow as a function of the strain amplitude, the frequency and the magnetic flux density was also investigated.

  19. A comparative study of the number and mass of fine particles emitted with diesel fuel and marine gas oil (MGO)

    NASA Astrophysics Data System (ADS)

    Nabi, Md. Nurun; Brown, Richard J.; Ristovski, Zoran; Hustad, Johan Einar

    2012-09-01

    The current investigation reports on diesel particulate matter emissions, with special interest in fine particles from the combustion of two base fuels. The base fuels selected were diesel fuel and marine gas oil (MGO). The experiments were conducted with a four-stroke, six-cylinder, direct injection diesel engine. The results showed that the fine particle number emissions measured by both SMPS and ELPI were higher with MGO compared to diesel fuel. It was observed that the fine particle number emissions with the two base fuels were quantitatively different but qualitatively similar. The gravimetric (mass basis) measurement also showed higher total particulate matter (TPM) emissions with the MGO. The smoke emissions, which were part of TPM, were also higher for the MGO. No significant changes in the mass flow rate of fuel and the brake-specific fuel consumption (BSFC) were observed between the two base fuels.

  20. Nanostructure of metallic particles in light water reactor used nuclear fuel

    NASA Astrophysics Data System (ADS)

    Buck, Edgar C.; Mausolf, Edward J.; McNamara, Bruce K.; Soderquist, Chuck Z.; Schwantes, Jon M.

    2015-06-01

    An extraordinary nano-structure has been observed in the metallic (Mo-Tc-Ru-Rh-Pd) particles that are known to form during irradiated in light water nuclear reactor fuels. This structure points possible high catalytic reactivity through the occurrence of a very high surface area as well as defect sites. We have analyzed separated metallic particles from dissolved high burn-up spent nuclear fuel using scanning and transmission electron microscopy. The larger particles vary in diameter between ∼10 and ∼300 nm and possess a hexagonally close packed epsilon-ruthenium structure. These particles are not always single crystals but often consist of much smaller crystallites on the order of 1-3 nm in diameter with evidence suggesting the occurrence of some amorphous regions. It is possible that neutron irradiation and fission product recoils generated the unusual small crystallite size. The composition of the metallic particles was variable with low levels of uranium present in some of the particles. We hypothesize that the uranium may have induced the formation of the amorphous (or frustrated) metal structure. This unique nano-structure may play an important role in the environmental behavior of nuclear fuels.

  1. An investigation of the typical corrosion parameters used to test polymer electrolyte fuel cell bipolar plate coatings, with titanium nitride coated stainless steel as a case study

    NASA Astrophysics Data System (ADS)

    Orsi, A.; Kongstein, O. E.; Hamilton, P. J.; Oedegaard, A.; Svenum, I. H.; Cooke, K.

    2015-07-01

    Stainless steel bipolar plates (BPP) for polymer electrolyte membrane fuel cells (PEMFCs) have good manufacturability, durability and low costs, but inadequate corrosion resistance and elevated interfacial contact resistance (ICR) in the fuel cell environment. Thin film coatings of titanium nitride (TiN) of 1 μm in thickness, were deposited by means of physical vapour deposition (PVD) process on to stainless steel (SS) 316L substrates and were evaluated, in a series of tests, for their level of corrosion protection and ICR. In the ex-situ corrosion tests, variables such as applied potential, experimental duration and pH of the sulphate electrolyte at 80 °C were altered. The ICR values were found to increase after exposure to greater applied potentials and electrolytes of a higher pH. In terms of experimental duration, the ICR increased most rapidly at the beginning of each experiment. It was also found that the oxidation of TiN was accelerated after exposure to electrolytes of a higher pH. When coated BPPs were incorporated into an accelerated fuel cell test, the degradation of the fuel cell cathode resembled the plates that were tested at the highest anodic potential (1.4 VSHE).

  2. Corrosion resistant PEM fuel cell

    DOEpatents

    Fronk, Matthew Howard; Borup, Rodney Lynn; Hulett, Jay S.; Brady, Brian K. NY); Cunningham, Kevin M.

    2011-06-07

    A PEM fuel cell having electrical contact elements comprising a corrosion-susceptible substrate metal coated with an electrically conductive, corrosion-resistant polymer containing a plurality of electrically conductive, corrosion-resistant filler particles. The substrate may have an oxidizable metal first layer (e.g., stainless steel) underlying the polymer coating.

  3. Corrosion resistant PEM fuel cell

    DOEpatents

    Fronk, Matthew Howard; Borup, Rodney Lynn; Hulett, Jay S.; Brady, Brian K.; Cunningham, Kevin M.

    2002-01-01

    A PEM fuel cell having electrical contact elements comprising a corrosion-susceptible substrate metal coated with an electrically conductive, corrosion-resistant polymer containing a plurality of electrically conductive, corrosion-resistant filler particles. The substrate may have an oxidizable metal first layer (e.g., stainless steel) underlying the polymer coating.

  4. Effects of Alternative Fuels and Aromatics on Gas-Turbine Particle Emissions

    NASA Astrophysics Data System (ADS)

    Thornhill, K. L., II; Moore, R.; Winstead, E.; Anderson, B. E.; Klettlinger, J. L.; Ross, R. C.; Surgenor, A.

    2015-12-01

    This presentation describes experiments conducted with a Honeywell GTCP36-150 Auxiliary Power Unit (APU) to evaluate the effects of varying fuel composition on particle emissions. The APU uses a single-stage compressor stage, gas turbine engine with a can-type combustor to generate bypass flow and electrical power for supporting small aircraft and helicopters. It is installed in a "hush-house" at NASA Glenn Research Center and is configured as a stand-alone unit that can be fueled from an onboard tank or external supply. It operates at constant RPM, but its fuel flow can be varied by changing the electrical load or volume of bypass flow. For these tests, an external bank of resistors were attached to the APU's DC and AC electrical outlets and emissions measurements were made at low, medium and maximum electrical current loads. Exhaust samples were drawn from several points downstream in the exhaust duct and fed to an extensive suite of gas and aerosol sensors installed within a mobile laboratory parked nearby. Aromatic- and sulfur-free synthetic kerosenes from Rentech, Gevo, UOP, Amyris and Sasol were tested and their potential to reduce PM emissions evaluated against a single Jet A1 base fuel. The role of aromatic compounds in regulating soot emissions was also evaluated by adding metered amounts of aromatic blends (Aro-100, AF-Blend, SAK) and pure compounds (tetracontane and 1-methylnaphthalene) to a base alternative fuel (Sasol). Results show that, relative to Jet A1, alternative fuels reduce nonvolatile particle number emissions by 50-80% and--by virtue of producing much smaller particles—mass emissions by 65-90%; fuels with the highest hydrogen content produced the greatest reductions. Nonvolatile particle emissions varied in proportion to fuel aromatic content, with additives containing the most complex ring structures producing the greatest emission enhancements.

  5. Evaluation of Cyanex 923-coated magnetic particles for the extraction and separation of lanthanides and actinides from nuclear waste streams

    NASA Astrophysics Data System (ADS)

    Shaibu, B. S.; Reddy, M. L. P.; Bhattacharyya, A.; Manchanda, V. K.

    2006-06-01

    In the magnetically assisted chemical separation (MACS) process, tiny ferromagnetic particles coated with solvent extractant are used to selectively separate radionuclides and hazardous metals from aqueous waste streams. The contaminant-loaded particles are then recovered from the waste solutions using a magnetic field. The contaminants attached to the magnetic particles are subsequently removed using a small volume of stripping agent. In the present study, Cyanex 923 (trialkylphosphine oxide) coated magnetic particles (cross-linked polyacrylamide and acrylic acid entrapping charcoal and iron oxide, 1:1:1, particle size=1-60 μm) are being evaluated for the possible application in the extraction and separation of lanthanides and actinides from nuclear waste streams. The uptake behaviour of Th(IV), U(VI), Am(III) and Eu(III) from nitric acid solutions was investigated by batch studies. The effects of sorption kinetics, extractant and nitric acid concentrations on the uptake behaviour of metal ions were systematically studied. The influence of fission products (Cs(I), Sr(II)) and interfering ions including Fe(III), Cr(VI), Mg(II), Mn(II), and Al(III) were investigated. The recycling capacity of the extractant-coated magnetic particles was also evaluated.

  6. Anion exchange polymer coated graphite granule electrodes for improving the performance of anodes in unbuffered microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Xu; Li, Dengfeng; Mao, Xuhui; Yu, Eileen Hao; Scott, Keith; Zhang, Enren; Wang, Dihua

    2016-10-01

    In this paper, graphite granule composite electrodes are prepared for microbial fuel cells (MFCs) by coating commercial graphite granules with the mixture of quaternary DABCO polysulfone or Nafion ion exchange polymer and carbon black. The results of electrochemical impedance spectroscopy (EIS) suggest that the addition of carbon black could significantly improve the electrical conductivity of graphite granule anodes. When phosphate buffer solution (PBS) is replaced by NaCl solution, the current densities of the pristine anode, 0.08 g Nafion coated anode and 0.16 g QDPSU coated anode decrease by 52.6%, 20.6% and 10.3% at -0.2 V (vs. Ag/AgCl), respectively. The solution resistance of ion exchange polymer coated anodes is more stable in comparison with that of pristine anode. After 40 operational days, the performance drop of 0.16 g QDPSU coated anode when switching the solution from PBS to NaCl is still smaller than that of pristine anode. However, 0.08 g Nafion coated anode shows the similar performance in NaCl solution to the pristine anode after long term operation. This study reveals that QDPSU anion exchange polymer is more suitable for the anode modification. The QDPSU coated anode promises a great potential for three-dimensional anode based MFCs to treat domestic wastewater.

  7. Effect of titania particles on the microstructure and properties of the epoxy resin coatings on sintered NdFeB permanent magnets

    NASA Astrophysics Data System (ADS)

    Xu, J. L.; Huang, Z. X.; Luo, J. M.; Zhong, Z. C.

    2014-04-01

    The nanometer titania particles enhanced epoxy resin composite coatings were prepared on the sintered NdFeB permanent magnets by cathodic electrophoretic deposition. The effects of titania particle concentrations on the microstructure and properties of the epoxy coatings were investigated by surface and cross-sectional morphologies observation, surface roughness and microhardness measurement, H2SO4 solution immersion test, neutral salt spray test and magnetic properties measurement. The results showed that the thickness of epoxy coatings with and without the titania particles addition was about 40 μm. The titania particles could be uniformly dispersed and embedded in the epoxy matrix if the titania particles concentration was lower than 40 g/l. With increasing titania particle concentrations, the number of the particles embedded in the epoxy matrix increased and the surface roughness and microhardness of the composite coatings increased. At the same time, the weight loss of the coated samples immersed in H2SO4 solution decreased and the neutral salt spray time of the coated samples prolonged. It could be concluded that the titania particles did not change the thickness of the epoxy coatings and did not deteriorate the magnetic properties of NdFeB substrates, but could greatly improve the microhardness and corrosion resistance of the epoxy coatings.

  8. Morphology and orientational behavior of silica-coated spindle-type hematite particles in a magnetic field probed by small-angle X-ray scattering.

    PubMed

    Reufer, Mathias; Dietsch, Hervé; Gasser, Urs; Hirt, Ann; Menzel, Andreas; Schurtenberger, Peter

    2010-04-15

    Form factor and magnetic properties of silica-coated spindle-type hematite nanoparticles are determined from SAXS measurements with applied magnetic field and magnetometry measurements. The particle size, polydispersity and porosity are determined using a core-shell model for the form factor. The particles are found to align with their long axis perpendicular to the applied field. The orientational order is determined from the SAXS data and compared to the orientational order obtained from magnetometry. The direct access to both, the orientational order of the particles, and the magnetic moments allow one to determine the magnetic properties of the individual spindle-type hematite particles. We study the influence of the silica coating on the magnetic properties and find a fundamentally different behavior of silica-coated particles. The silica coating reduces the effective magnetic moment of the particles. This effect is enhanced with field strength and can be explained by superparamagnetic relaxation in the highly porous particles.

  9. Novel application of hot-melt extrusion for the preparation of monolithic matrices containing enteric-coated particles.

    PubMed

    Schilling, Sandra U; McGinity, James W

    2010-11-15

    The objective was to investigate a novel application of hot-melt extrusion for the preparation of multiparticulate matrices comprising delayed-release particles. Multiparticulates of different mechanical strengths (theophylline granules, wet-mass extruded/spheronized pellets and drug-layered microcrystalline cellulose spheres) were coated with Eudragit(®) L30D-55 and characterized regarding potency, moisture content, dissolution properties and tensile strength. The coated particles were incorporated into a water-soluble matrix using hot-melt extrusion. Six hydrophilic polymers including polyethylene glycols, poloxamers and polyethylene oxides were studied as the carrier material for the extrusion. Dissolution testing showed that the maintenance of the delayed-release properties of the incorporated particles was independent of the particle tensile strength, but influenced by the nature of the carrier polymer. High miscibility between the carrier and the coating polymer correlated with increased film permeability and higher drug release in acidic media. Of the materials tested, poloxamer 407 exhibited lower miscibility with the Eudragit(®) L polymer and matrices containing up to 40% enteric pellets were compliant with the USP dissolution requirements for delayed-release dosage forms. The potential advantages of hot-melt extrusion over direct compression for the processing of soft drug granules coated with Eudragit(®) L polymer were demonstrated.

  10. Tribological Properties of Hard Metal Coatings Sprayed by High-Velocity Air Fuel Process

    NASA Astrophysics Data System (ADS)

    Lyphout, C.; Sato, K.; Houdkova, S.; Smazalova, E.; Lusvarghi, L.; Bolelli, G.; Sassatelli, P.

    2016-01-01

    Lowering the thermal energy and increasing the kinetic energy of hard metal particles sprayed by the newly developed HVAF systems can significantly reduce their decarburization, and increases the sliding wear and corrosion resistance of the resulting coatings, making the HVAF technique attractive, both economically and environmentally, over its HVOF predecessors. Two agglomerated and sintered feedstock powder chemistries, WC-Co (88/12) and WC-CoCr (86/10/4), respectively, with increasing primary carbides grain size from 0.2 to 4.0 microns, have been deposited by the latest HVAF-M3 process onto carbon steel substrates. Their dry sliding wear behaviors and friction coefficients were evaluated at room temperature via Ball-on-disk (ASTM G99-90) wear tests against Al2O3 counterparts, and via Pin-on-disk (ASTM G77-05) wear tests against modified martensitic steel counterparts in both dry and lubricated conditions. Sliding wear mechanisms, with the formation of wavy surface morphology and brittle cracking, are discussed regarding the distribution and size of primary carbides. Corrosion behaviors were evaluated via standard Neutral Salt Spray, Acetic Acid Salt Spray, accelerated corrosion test, and electrochemical polarization test at room temperature. The optimization of the tribological properties of the coatings is discussed, focusing on the suitable selection of primary carbide size for different working load applications.

  11. Characterization and irradiation performance of HTGR Biso-coated fertile particles in HFIR experiments HT-28, -29, and -30

    SciTech Connect

    Long, E.L. Jr.; Krautwasser, P.; Beatty, R.L.; Kania, M.J.; Morgan, C.S. Jr.; Yust, C.S.

    1980-07-01

    Capsules HT-28, -29, and -30 were irradiated in the target region of the High Flux Isotope Reactor at ORNL to determine the relative fast-neutron stability of pyrolytic carbons that had been prepared in a small laboratory coating furnace with various deposition conditions. The pyrolytic carbon coatings of 22 batches of particles of HTGR design were characterized by various methods, including optical anisotropy measurements, hot gaseous chlorine leaching, plasma oxidation, small-angle x-ray scattering (SAXS) measurements, mercury intrusion, immersion density, and, in a few cases, neon-helium permeability measurements. The results of the above measurements were used to quantify microstructural differences between pyrolytic coatings derived at various conditions and to correlate the performance of the coatings with the measured properties. The most consistent results were obtained by comparing various pore size distributions within the coatings (determined from SAXS measurements) with immersion density, mercury intrusion, chlorine leaching, and neon-helium permeability results and with irradiation performance of the coatings. This study also demonstrated that care must be exercised if experiments on coatings containing inert carbon kernels that were codeposited along with dense thoria kernels are to yield meaningful results.

  12. Study of electrodeposited polypyrrole coatings for the corrosion protection of stainless steel bipolar plates for the PEM fuel cell

    NASA Astrophysics Data System (ADS)

    García, M. A. Lucio; Smit, Mascha A.

    Polypyrrole coatings were prepared on stainless steel SS304 in order to study the corrosion protection provided by the conductive polymer in a simulated PEM fuel cell environment. The polypyrrole was deposited by electrochemical polymerization with 0.04, 0.07 and 0.14 g cm -2 onto SS304 electrodes. Polarization curves, taken after immersion for 1, 3 or 24 h in 0.1 M sulphuric acid at either room temperature or 60 °C were used as an accelerated test. For short immersion times, it was found that corrosion current densities (at free corrosion potentials), diminished up to 2 orders of magnitude for samples tested at room temperature and up to 4 orders of magnitude for samples tested at 60 °C. Furthermore, at potentials in the range of the PEM fuel cell anode potential, corrosion rates also decreased up to several orders of magnitude. However, these protective properties were lost at longer times of immersion. The addition of DBSA to the polypyrrole coatings did lead to improved corrosion current densities at the free corrosion potential, however due to the loss of passivity of these samples, the corrosion rates in the potential range applicable to PEM fuel cells were either similar to or larger than bare metal. SEM was used to determine the morphology of the coatings and showed that the most homogeneous coating was obtained for 0.07 g cm -2 polypyrrole, without the incorporation of DBSA.

  13. The Generation of Turnip Crinkle Virus-Like Particles in Plants by the Transient Expression of Wild-Type and Modified Forms of Its Coat Protein

    PubMed Central

    Saunders, Keith; Lomonossoff, George P.

    2015-01-01

    Turnip crinkle virus (TCV), a member of the genus carmovirus of the Tombusviridae family, has a genome consisting of a single positive-sense RNA molecule that is encapsidated in an icosahedral particle composed of 180 copies of a single type of coat protein. We have employed the CPMV-HT transient expression system to investigate the formation of TCV-like particles following the expression of the wild-type coat protein or modified forms of it that contain either deletions and/or additions. Transient expression of the coat protein in plants results in the formation of capsid structures that morphologically resemble TCV virions (T = 3 structure) but encapsidate heterogeneous cellular RNAs, rather than the specific TCV coat protein messenger RNA. Expression of an amino-terminal deleted form of the coat protein resulted in the formation of smaller T = 1 structures that are free of RNA. The possibility of utilizing TCV as a carrier for the presentation of foreign proteins on the particle surface was also explored by fusing the sequence of GFP to the C-terminus of the coat protein. The expression of coat protein-GFP hybrids permitted the formation of VLPs but the yield of particles is diminished compared to the yield obtained with unmodified coat protein. Our results confirm the importance of the N-terminus of the coat protein for the encapsidation of RNA and show that the coat protein's exterior P domain plays a key role in particle formation. PMID:26734041

  14. The Effect Of Organic Surfactants On The Properties Of Common Hygroscopic Particles: Effective Densities, Reactivity And Water Evaporation Of Surfactant Coated Particles

    NASA Astrophysics Data System (ADS)

    Cuadrarodriguez, L.; Zelenyuk, A.; Imre, D.; Ellison, B.

    2006-12-01

    Measurements of atmospheric aerosol compositions routinely show that organic compounds account for a very large fraction of the particle mass. The organic compounds that make up this aerosol mass represent a wide range of molecules with a variety of properties. Many of the particles are composed of hygroscopic salts like sulfates, nitrates and sea-salt internally mixed with organics. While the properties of the hygroscopic salts are known, the effect of the organic compounds on the microphysical and chemical properties which include CCN activity is not clear. .One particularly interesting class of internally mixed particles is composed of aqueous salts solutions that are coated with organic surfactants which are molecules with long aliphatic chain and a water soluble end. Because these molecules tend to coat the particles' surfaces, a monolayer might be sufficient to drastically alter their hygroscopic properties, their CCN activity, and reactivity. The aliphatic chains, being exposed to the oxidizing atmosphere are expected to be transformed through heterogeneous chemistry, yielding complex products with mixed properties. We will report the results from a series of observations on ammonium sulfate, sodium chloride and sea salt particles coated with three types of surfactant molecules: sodium lauryl sulfate, sodium oleate and laurtrimonium chloride. We have been able to measure the effective densities of internally mixed particles with a range of surfactant concentration that start below a monolayer and extend all the way to particles composed of pure surfactant. For many of the measurements the data reveal a rather complex picture that cannot be simply interpreted in terms of the known pure-compound densities. For unsaturated hydrocarbons we observed and quantified the effect of oxidation by ozone on particle size, effective density and individual particle mass spectral signatures. One of the more important properties of these surfactants is that they can form a

  15. Combustion characteristics of fuel droplets with addition of nano and micron-sized aluminum particles

    SciTech Connect

    Gan, Yanan; Qiao, Li

    2011-02-15

    The burning characteristics of fuel droplets containing nano and micron-sized aluminum particles were investigated. Particle size, surfactant concentration, and the type of base fluid were varied. In general, nanosuspensions can last much longer than micron suspensions, and ethanol-based fuels were found to achieve much better suspension than n-decane-based fuels. Five distinctive stages (preheating and ignition, classical combustion, microexplosion, surfactant flame, and aluminum droplet flame) were identified for an n-decane/nano-Al droplet, while only the first three stages occurred for an n-decane/micron-Al droplet. For the same solid loading rate and surfactant concentration, the disruption and microexplosion behavior of the micron suspension occurred later with much stronger intensity. The intense droplet fragmentation was accompanied by shell rupture, which caused a massive explosion of particles, and most of them were burned during this event. On the contrary, for the nanosuspension, combustion of the large agglomerate at the later stage requires a longer time and is less complete because of formation of an oxide shell on the surface. This difference is mainly due to the different structure and characteristics of particle agglomerates formed during the early stage, which is a spherical, porous, and more-uniformly distributed aggregate for the nanosuspension, but it is a densely packed and impermeable shell for the micron suspension. A theoretical analysis was then conducted to understand the effect of particle size on particle collision mechanism and aggregation rate. The results show that for nanosuspensions, particle collision and aggregation are dominated by the random Brownian motion. For micron suspensions, however, they are dominated by fluid motion such as droplet surface regression, droplet expansion resulting from bubble formation, and internal circulation. And the Brownian motion is the least important. This theoretical analysis explains the

  16. Single-Particle Laboratory Studies of Heterogeneous H2O and HCl Processing on Clean and H2SO4-Coated Aluminum Oxide Particles

    NASA Astrophysics Data System (ADS)

    Hunter, A. J.; Sonnenfroh, D. M.; Rawlins, W. T.

    2001-12-01

    Aluminum oxide particles exhausted from solid rocket motors may affect tropospheric and stratospheric radiative balance through nucleation and growth of water ice clouds, both locally in launch corridors and globally. These particles also are active toward chemisorption of HCl and dissociative chemisorption of CFCs. Plume particle surfaces are likely to contain H2SO4, possibly altering their activities toward uptake and chemical processing of HCl and HNO3. We have investigated activities of different types of aluminum oxide particles for uptake of gas-phase H2O and HCl, using a single-particle electrodynamic levitation apparatus. The particle types investigated were clean and H2SO4-treated alpha-Al2O3 and gamma-Al2O3. We also investigated metastable Al2O3 particles formed by rapid cooling from molten particles in a shock tube, analogous to particle processing in a rocket exhaust nozzle. Particles were treated with H2SO4 by vapor deposition in an oven. The kinetic measurements consisted of independent, simultaneous observations of mass uptake and particle size increase upon exposure of single levitated particles to fixed concentrations of H2O or HCl in slowly flowing gas mixtures at 1 atm. Alpha and gamma Al2O3 were essentially inert toward H2O and HCl uptake, however they readily adsorbed monolayer-equivalent levels of H2SO4 vapor. H2SO4-coated and metastable particles were active toward H2O and HCl uptake. The measured uptake efficiencies imply fast reaction rates within rocket exhaust plumes, potentially leading to CCN behavior as well as heterogeneous chlorine activation by these particles. This research was supported by the Air Force Office of Scientific Research.

  17. Reusable nanosilver-coated magnetic particles for ultrasensitive SERS-based detection of malachite green in water samples.

    PubMed

    Song, Dan; Yang, Rong; Wang, Chongwen; Xiao, Rui; Long, Feng

    2016-03-11

    A novel nanosilver-deposited silica-coated Fe3O4 magnetic particle (Fe3O4@SiO2@Ag) with uniform size, good SERS activity and magnetic responsiveness was synthesized using amination polymer. The Fe3O4@SiO2@Ag magnetic particles have been successfully applied for ultrasensitive SERS detection of malachite green (MG) in water samples. The mechanism is that MG can be adsorbed on the silver surface of nanosilver-coated magnetic particles via one nitrogen atom, and the Raman signal intensity of MG is significantly enhanced by the nanosilver layer formed on the magnetic particles. The developed sensing system exhibited a sensitive response to MG in the range of 10 fM to 100 μM with a low limit of detection (LOD) 2 fM under optimal conditions. The LOD was several orders of magnitude lower than those of other methods. This SERS-based sensor showed good reproducibility and stability for MG detection. The silver-coated magnetic particles could easily be regenerated as SERS substrates only using low pH solution for multiple sensing events. The recovery of MG added to several water samples at different concentrations ranged from 90% to 110%. The proposed method facilitates the ultrasensitive analysis of dyes to satisfy the high demand for ensuring the safety of water sources.

  18. Reusable nanosilver-coated magnetic particles for ultrasensitive SERS-based detection of malachite green in water samples

    NASA Astrophysics Data System (ADS)

    Song, Dan; Yang, Rong; Wang, Chongwen; Xiao, Rui; Long, Feng

    2016-03-01

    A novel nanosilver-deposited silica-coated Fe3O4 magnetic particle (Fe3O4@SiO2@Ag) with uniform size, good SERS activity and magnetic responsiveness was synthesized using amination polymer. The Fe3O4@SiO2@Ag magnetic particles have been successfully applied for ultrasensitive SERS detection of malachite green (MG) in water samples. The mechanism is that MG can be adsorbed on the silver surface of nanosilver-coated magnetic particles via one nitrogen atom, and the Raman signal intensity of MG is significantly enhanced by the nanosilver layer formed on the magnetic particles. The developed sensing system exhibited a sensitive response to MG in the range of 10 fM to 100 μM with a low limit of detection (LOD) 2 fM under optimal conditions. The LOD was several orders of magnitude lower than those of other methods. This SERS-based sensor showed good reproducibility and stability for MG detection. The silver-coated magnetic particles could easily be regenerated as SERS substrates only using low pH solution for multiple sensing events. The recovery of MG added to several water samples at different concentrations ranged from 90% to 110%. The proposed method facilitates the ultrasensitive analysis of dyes to satisfy the high demand for ensuring the safety of water sources.

  19. Reusable nanosilver-coated magnetic particles for ultrasensitive SERS-based detection of malachite green in water samples

    PubMed Central

    Song, Dan; Yang, Rong; Wang, Chongwen; Xiao, Rui; Long, Feng

    2016-01-01

    A novel nanosilver-deposited silica-coated Fe3O4 magnetic particle (Fe3O4@SiO2@Ag) with uniform size, good SERS activity and magnetic responsiveness was synthesized using amination polymer. The Fe3O4@SiO2@Ag magnetic particles have been successfully applied for ultrasensitive SERS detection of malachite green (MG) in water samples. The mechanism is that MG can be adsorbed on the silver surface of nanosilver-coated magnetic particles via one nitrogen atom, and the Raman signal intensity of MG is significantly enhanced by the nanosilver layer formed on the magnetic particles. The developed sensing system exhibited a sensitive response to MG in the range of 10 fM to 100 μM with a low limit of detection (LOD) 2 fM under optimal conditions. The LOD was several orders of magnitude lower than those of other methods. This SERS-based sensor showed good reproducibility and stability for MG detection. The silver-coated magnetic particles could easily be regenerated as SERS substrates only using low pH solution for multiple sensing events. The recovery of MG added to several water samples at different concentrations ranged from 90% to 110%. The proposed method facilitates the ultrasensitive analysis of dyes to satisfy the high demand for ensuring the safety of water sources. PMID:26964502

  20. Role of the size of particles of alumina trihydrate filler on the life of RTV silicone rubber coating

    SciTech Connect

    Deng, H.; Hackam, R.; Cherney, E.A. |

    1995-04-01

    The paper reports on a study of the influence of the size of the particles of Alumina trihydrate (ATH) filler on the life of RTV silicone rubber coating in a salt-fog chamber. The particle sizes examined include 1.0, 4.5, 13, 17 and 75{mu}m. The optimum size to give the lowest leakage current and the longest time to failure of the coating is determined. The particle size affects the roughness of the coating. This is determined by a high resolution surface roughness tester and a scanning electron microscope (SEM) examination. The roughness is enhanced after prolonged test in salt-fog. The leakage current affects the amount of silicone fluid on the surface. The amount of silicone fluid present on the surface after exposure to dry-band arcing in salt-fog is a function of the particle size. Measurements of surface roughness, the amount of silicone fluid on the surface and the leakage current combined with theoretical analysis of the heat conduction lead to identification of the mechanisms by which the size of the ATH particle impart resistance to tracking and erosion.

  1. Reusable nanosilver-coated magnetic particles for ultrasensitive SERS-based detection of malachite green in water samples.

    PubMed

    Song, Dan; Yang, Rong; Wang, Chongwen; Xiao, Rui; Long, Feng

    2016-01-01

    A novel nanosilver-deposited silica-coated Fe3O4 magnetic particle (Fe3O4@SiO2@Ag) with uniform size, good SERS activity and magnetic responsiveness was synthesized using amination polymer. The Fe3O4@SiO2@Ag magnetic particles have been successfully applied for ultrasensitive SERS detection of malachite green (MG) in water samples. The mechanism is that MG can be adsorbed on the silver surface of nanosilver-coated magnetic particles via one nitrogen atom, and the Raman signal intensity of MG is significantly enhanced by the nanosilver layer formed on the magnetic particles. The developed sensing system exhibited a sensitive response to MG in the range of 10 fM to 100 μM with a low limit of detection (LOD) 2 fM under optimal conditions. The LOD was several orders of magnitude lower than those of other methods. This SERS-based sensor showed good reproducibility and stability for MG detection. The silver-coated magnetic particles could easily be regenerated as SERS substrates only using low pH solution for multiple sensing events. The recovery of MG added to several water samples at different concentrations ranged from 90% to 110%. The proposed method facilitates the ultrasensitive analysis of dyes to satisfy the high demand for ensuring the safety of water sources. PMID:26964502

  2. Emissions from the laboratory combustion of wildland fuels: Particle morphology and size

    NASA Astrophysics Data System (ADS)

    Chakrabarty, Rajan K.; Moosmüller, Hans; Garro, Mark A.; Arnott, W. Patrick; Walker, John; Susott, Ronald A.; Babbitt, Ronald E.; Wold, Cyle E.; Lincoln, Emily N.; Hao, Wei Min

    2006-04-01

    The morphology of particles emitted by wildland fires contributes to their physical and chemical properties but is rarely determined. As part of a study at the USFS Fire Sciences Laboratory (FSL) investigating properties of particulate matter emitted by fires, we studied the size, morphology, and microstructure of particles emitted from the combustion of eight different wildland fuels (i.e., sagebrush, poplar wood, ponderosa pine wood, ponderosa pine needles, white pine needles, tundra cores, and two grasses) by scanning electron microscopy. Six of these fuels were dry, while two fuels, namely the tundra cores and one of the grasses, had high fuel moisture content. The particle images were analyzed for their density and textural fractal dimensions, their monomer and agglomerate number size distributions, and three different shape descriptors, namely aspect ratio, root form factor, and roundness. The particles were also probed with energy dispersive X-ray spectroscopy confirming their carbonaceous nature. The density fractal dimension of the agglomerates was determined using two different techniques, one taking into account the three-dimensional nature of the particles, yielding values between 1.67 and 1.83, the other taking into account only the two-dimensional orientation, yielding values between 1.68 and 1.74. The textural fractal dimension that describes the roughness of the boundary of the two-dimensional projection of the particle was between 1.10 and 1.19. The maximum length of agglomerates was proportional to a power a of their diameter and the proportionality constant and the three shape descriptors were parameterized as function of the exponent a.

  3. Physicochemical characteristics, oxidative capacities and cytotoxicities of sulfate-coated, 1,4-NQ-coated and ozone-aged black carbon particles

    NASA Astrophysics Data System (ADS)

    Li, Qian; Shang, Jing; Liu, Jia; Xu, Weiwei; Feng, Xiang; Li, Rui; Zhu, Tong

    2015-02-01

    Black carbon (BC) particles play important roles in climate change, visibility impairment, atmospheric reaction process, and health effect. The aging processes of BC alter not only atmospheric composition, but also the physicochemical characteristics of BC itself, thus impacting the environment and health effects. Here, three types of BC including sulfate-coated, 1,4-naphthoquinone (1,4-NQ)-coated, and O3-aged BC are presented. The morphologies, structures, extraction components, the amount of water-soluble organic carbon (WSOC) and free radical intensities of the three types of BC particles are examined by transmission electron microscopy, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), ultraviolet-visible spectrophotometry, total organic carbon detector and electron paramagnetic resonance, respectively. Dithiothreitol (DTT) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide assays are utilized to assess the changes in oxidative capacity and cytotoxicity towards murine alveolar macrophage cells. The orders of DTT activities and cytotoxicities of the particles are both arranged as follows: BC/1,4-NQ > BC/O3 > BC > BC/sulfate, mainly because 1,4-NQ owned high oxidative potential and cytotoxicity, while sulfate did not exhibit oxidative capacity and cytotoxicity. The insoluble components of particles contribute most of the total DTT activity, whereas either water or methanol extract is minor contributor. DTT activity was positively correlated with both WSOC content and free radical intensity, with the correlation between DTT activity and WSOC content was stronger than that between DTT activity and free radical intensity.

  4. Specific zeta-potential response of layer-by-layer coated colloidal particles triggered by polyelectrolyte ion interactions.

    PubMed

    Irigoyen, J; Moya, S E; Iturri, J J; Llarena, I; Azzaroni, O; Donath, E

    2009-04-01

    The zeta-potential of PSS/PAH and PSS/PDADMAC coated silica particles was studied in the presence of ClO4(-) and H2PO4(-) salts. In the presence of ClO4(-), layer-by-layer (LbL) coated silica particles with PDADMAC as the top layer show a reversal in the surface charge with increasing salt concentration but remain positive in phosphate solutions. LbL particles with PAH as the top layer become, however, negative in the presence of H2PO4(-) but retain their positive charge in the presence of ClO4(-). Charge reversal was explained by specific interaction of ClO4(-) ions with the quaternary amine groups and of H2PO4(-) with the primary amines through hydrogen bonding. Atomic force microscopy (AFM) and quartz crystal microbalance with dissipation (QCM-D) were employed to study the corresponding layer stability on planar surfaces.

  5. Fabrication and Preliminary Evaluation of Metal Matrix Microencapsulated Fuels

    SciTech Connect

    Terrani, Kurt A; Kiggans, Jim; Snead, Lance Lewis

    2012-01-01

    The metal matrix microencapsulated (M3) fuel concept for light water reactors (LWRs), consisting of coated fuel particles dispersed in a zirconium metal matrix, is introduced. Fabrication of M3 fuels by hot pressing, hot isostatic pressing, or extrusion methodologies has been demonstrated over the temperature range 800-1050 C. Various types of coated fuel particles with outermost layers of pyrocarbon, SiC, ZrC, and TiN have been incorporated into the zirconium metal matrix. Mechanical particle-particle and chemical particle-matrix interactions have been observed during the preliminary characterization of as-fabricated M3 specimens. Irradiation of three M3 rodlets with surrogate coated fuel particles was carried out at mean rod temperature of 400 C to 4.6 dpa in the zirconium metal matrix. Due to absence of texture in the metal matrix no irradiation growth strain (<0.09%) was detected during the post-irradiation examination.

  6. [Research on NEDC ultrafine particle emission characters of a port fuel injection gasoline car].

    PubMed

    Hu, Zhi-Yuan; Li, Jin; Tan, Pi-Qiang; Lou, Di-Ming

    2012-12-01

    A Santana gasoline car with multi-port fuel injection (PFI) system was used as the research prototype and an engine exhaust particle sizer (EEPS) was employed to investigate the exhaust ultrafine particle number and size distribution characters of the tested vehicle in new European driving cycle (NEDC). The tested results showed that the vehicle's nuclear particle number, accumulation particle number, as well as the total particle number emission increased when the car drove in accelerated passage, and the vehicle's particle number emission was high during the first 40 seconds after test started and when the speed was over 90 km x h(-1) in extra urban driving cycle (EUDC) in NEDC. The ultrafine particle distribution of the whole NEDC showed a single peak logarithmic distribution, with diameters of the peak particle number emission ranging from 10 nm to 30 nm, and the geometric mean diameter was 24 nm. The ultrafine particle distribution of the urban driving cycle named by the economic commission for Europe (ECE) e. g. ECE I, ECE II - IV, the extra urban driving cycle e. g. EUDC, and the idling, constant speed, acceleration, deceleration operation conditions of NEDC all showed a single peak logarithmic distribution, also with particle diameters of the peak particle number emission ranging from 10 nm to 30 nm, and the geometric mean diameters of different driving cycle and different driving mode were from 14 nm to 42 nm. Therefore, the ultrafine particle emissions of the tested PFI gasoline car were mainly consisted of nuclear mode particles with a diameter of less than 50 nm. PMID:23379140

  7. [Research on NEDC ultrafine particle emission characters of a port fuel injection gasoline car].

    PubMed

    Hu, Zhi-Yuan; Li, Jin; Tan, Pi-Qiang; Lou, Di-Ming

    2012-12-01

    A Santana gasoline car with multi-port fuel injection (PFI) system was used as the research prototype and an engine exhaust particle sizer (EEPS) was employed to investigate the exhaust ultrafine particle number and size distribution characters of the tested vehicle in new European driving cycle (NEDC). The tested results showed that the vehicle's nuclear particle number, accumulation particle number, as well as the total particle number emission increased when the car drove in accelerated passage, and the vehicle's particle number emission was high during the first 40 seconds after test started and when the speed was over 90 km x h(-1) in extra urban driving cycle (EUDC) in NEDC. The ultrafine particle distribution of the whole NEDC showed a single peak logarithmic distribution, with diameters of the peak particle number emission ranging from 10 nm to 30 nm, and the geometric mean diameter was 24 nm. The ultrafine particle distribution of the urban driving cycle named by the economic commission for Europe (ECE) e. g. ECE I, ECE II - IV, the extra urban driving cycle e. g. EUDC, and the idling, constant speed, acceleration, deceleration operation conditions of NEDC all showed a single peak logarithmic distribution, also with particle diameters of the peak particle number emission ranging from 10 nm to 30 nm, and the geometric mean diameters of different driving cycle and different driving mode were from 14 nm to 42 nm. Therefore, the ultrafine particle emissions of the tested PFI gasoline car were mainly consisted of nuclear mode particles with a diameter of less than 50 nm.

  8. Coated-vesicle shells, particle/chain material, and tubulin in brain synaptosomes. An electron microscope and biochemical study

    PubMed Central

    1976-01-01

    Coated vesicles (CVs), plain synaptic vesicles (PSVs), and nonvesicular flocculent material were isolated from synaptosomes and examined with goniometry and high-resolution electron microscopy after either negative staining or various biochemical procedures. The flocculent material (i.e. the presynaptic matrix material except CV shells) is largely composed of particulate or elongated (chainlike) structures; some of this material (here referred to as particle/chain material) is attached to PSVs. The results obtained were: (a) the proteinaceous properties of the CV coat (also referred to as CV shell) and the particle/chain material were demonstrated with chymotrypsin; (b) the CV shell, studied with various negative-staining techniques, differs from the particle/chain material since it has no 3-4-nm globular subunits and reacts differently to alkaline pH; (c) the particle/chain material consists of aggregates of 3-4-nm globular subunits, four of which yield 8-10-nm fine particles; and these particles can be further aggregated into chains 8-10 nm wide and up to 30-60 nm long showing a "hollow" core; (d) vinblastine sulfate induced ringlike or helical crystalloid precipitates closely resembling the vinblastine-induced microtubule crystals reported in the literature, but vinblastine had no effect on either the CV shell material or the particle/chain material. PMID:57963

  9. High temperature oxidation behavior of interconnect coated with LSCF and LSM for solid oxide fuel cell by screen printing

    NASA Astrophysics Data System (ADS)

    Lee, Shyong; Chu, Chun-Lin; Tsai, Ming-Jui; Lee, Jye

    2010-01-01

    The current study examined the effect of La 0.6Sr 0.4Co 0.2Fe 0.8O 3 (LSCF) and La 0.7Sr 0.3MnO 3 (LSM) coatings on the electrical properties and oxidation resistance of Crofer22 APU at 800 °C hot air. LSCF and LSM were coated on Crofer22 APU by screen printing and sintered over temperatures ranging from 1000 to 1100 °C in N 2. The coated alloy was first checked for compositions, morphology and interface conditions and then treated in a simulated oxidizing environment at 800 °C for 200 h. After measuring the long-term electrical resistance, the area specific resistance (ASR) at 800 °C for the alloy coated with LSCF was less than its counterpart coated with LSM. This work used LSCF coating as a metallic interconnect to reduce working temperature for the solid oxide fuel cell.

  10. A nanocrystalline zirconium carbide coating as a functional corrosion-resistant barrier for polymer electrolyte membrane fuel cell application

    NASA Astrophysics Data System (ADS)

    Xu, Jiang; Li, ZhengYang; Xu, Song; Munroe, Paul; Xie, Zong-Han

    2015-11-01

    A ZrC nanocrystalline coating is engineered onto a Ti-6Al-4V substrate using a double cathode glow discharge technique in order to improve the corrosion resistance and long-term stability of this alloy. The new coating exhibits an extremely dense, homogeneous microstructure composed of equiaxed grains with an average grain size of ∼12 nm and is well adhered on the surface of the substrate. The corrosion behaviour of the coating is systematically investigated using various electrochemical methods, including potentiodynamic, potentiostatic polarizations and electrochemical impedance spectroscopy (EIS), in a simulated polymer electrolyte membrane fuel cell (PEMFC) operating circumstances under different temperatures. The results show that with rising temperature, the corrosion potential (Ecorr) decreases and the corrosion current density (icorr) of the ZrC coated specimen increases, indicating that the corrosion resistance decreased with increasing temperature. However, at a given temperature, the ZrC-coated Ti-6Al-4V alloy has a higher Ecorr and lower icorr as compared to the bare substrate. The results of EIS measurements show that the values of the resistance for the ZrC coated Ti-6Al-4V alloy are three orders of magnitude larger than those of Ti-6A1-4V in the simulated PEMFC environment.

  11. Accelerator-Based Irradiation Creep of Pyrolytic Carbon Used in TRISO Fuel Particles for the (VHTR) Very Hight Temperature Reactors

    SciTech Connect

    Lumin Wang; Gary Was

    2010-07-30

    Pyrolytic carbon (PyC) is one of the important structural materials in the TRISO fuel particles which will be used in the next generation of gas-cooled very-high-temperature reactors (VHTR). When the TRISO particles are under irradiation at high temperatures, creep of the PyC layers may cause radial cracking leading to catastrophic particle failure. Therefore, a fundamental understanding of the creep behavior of PyC during irradiation is required to predict the overall fuel performance.

  12. Comparison of In-Flight Particle Properties, Splat Formation, and Coating Microstructure for Regular and Nano-YSZ Powders

    NASA Astrophysics Data System (ADS)

    Elsebaei, A.; Heberlein, J.; Elshaer, M.; Farouk, A.

    2010-01-01

    The relationship between atmospheric pressure plasma spray parameters and in-flight particle characteristics was determined. The morphologies of individual splats and the coating microstructure were studied for different stand-off distances and arc currents. Coating cross-sectional analysis showed that the total porosity of the coating increased with decreasing arc current, and increasing stand-off distance. Two different materials were used: the regular (r-YSZ) feed stock and the nano size (n-YSZ) agglomerated powder. The results illustrate that the r-YSZ coating has higher total porosity at higher arc currents than n-YSZ coating. The splat flattening degree and circularity was examined at different substrate temperatures for both powders. The results indicate that the flattening degree increased at high temperatures for the two materials, but the values for n-YSZ were higher than those for the r-YSZ. This study showed the operating regimes in which the use of n-YSZ yields improved coating properties.

  13. High-performance Fuel Cell with Stretched Catalyst-Coated Membrane: One-step Formation of Cracked Electrode

    PubMed Central

    Kim, Sang Moon; Ahn, Chi-Yeong; Cho, Yong-Hun; Kim, Sungjun; Hwang, Wonchan; Jang, Segeun; Shin, Sungsoo; Lee, Gunhee; Sung, Yung-Eun; Choi, Mansoo

    2016-01-01

    We have achieved performance enhancement of polymer electrolyte membrane fuel cell (PEMFC) though crack generation on its electrodes. It is the first attempt to enhance the performance of PEMFC by using cracks which are generally considered as defects. The pre-defined, cracked electrode was generated by stretching a catalyst-coated Nafion membrane. With the strain-stress property of the membrane that is unique in the aspect of plastic deformation, membrane electrolyte assembly (MEA) was successfully incorporated into the fuel cell. Cracked electrodes with the variation of strain were investigated and electrochemically evaluated. Remarkably, mechanical stretching of catalyst-coated Nafion membrane led to a decrease in membrane resistance and an improvement in mass transport, which resulted in enhanced device performance. PMID:27210793

  14. High-performance Fuel Cell with Stretched Catalyst-Coated Membrane: One-step Formation of Cracked Electrode

    NASA Astrophysics Data System (ADS)

    Kim, Sang Moon; Ahn, Chi-Yeong; Cho, Yong-Hun; Kim, Sungjun; Hwang, Wonchan; Jang, Segeun; Shin, Sungsoo; Lee, Gunhee; Sung, Yung-Eun; Choi, Mansoo

    2016-05-01

    We have achieved performance enhancement of polymer electrolyte membrane fuel cell (PEMFC) though crack generation on its electrodes. It is the first attempt to enhance the performance of PEMFC by using cracks which are generally considered as defects. The pre-defined, cracked electrode was generated by stretching a catalyst-coated Nafion membrane. With the strain-stress property of the membrane that is unique in the aspect of plastic deformation, membrane electrolyte assembly (MEA) was successfully incorporated into the fuel cell. Cracked electrodes with the variation of strain were investigated and electrochemically evaluated. Remarkably, mechanical stretching of catalyst-coated Nafion membrane led to a decrease in membrane resistance and an improvement in mass transport, which resulted in enhanced device performance.

  15. Mixing state of aerosols and direct observation of carbonaceous and marine coatings on African dust by individual particle analysis

    NASA Astrophysics Data System (ADS)

    Deboudt, Karine; Flament, Pascal; ChoëL, Marie; Gloter, Alexandre; Sobanska, Sophie; Colliex, Christian

    2010-12-01

    The mixing state of aerosols collected at M'Bour, Senegal, during the Special Observing Period conducted in January-February 2006 (SOP-0) of the African Monsoon Multidisciplinary Analysis project (AMMA), was studied by individual particle analysis. The sampling location on the Atlantic coast is particularly adapted for studying the mixing state of tropospheric aerosols since it is (1) located on the path of Saharan dust plumes transported westward over the northern tropical Atlantic, (2) influenced by biomass burning events particularly frequent from December to March, and (3) strongly influenced by anthropogenic emissions from polluted African cities. Particle size, morphology, and chemical composition were determined for 12,672 particles using scanning electron microscopy (automated SEM-EDX). Complementary analyses were performed using transmission electron microscopy combined with electron energy loss spectrometry (TEM-EELS) and Raman microspectrometry. Mineral dust and carbonaceous and marine compounds were predominantly found externally mixed, i.e., not present together in the same particles. Binary internally mixed particles, i.e., dust/carbonaceous, carbonaceous/marine, and dust/marine mixtures, accounted for a significant fraction of analyzed particles (from 10.5% to 46.5%). Western Sahara was identified as the main source of mineral dust. Two major types of carbonaceous particles were identified: "tar balls" probably coming from biomass burning emissions and soot from anthropogenic emissions. Regarding binary internally mixed particles, marine and carbonaceous compounds generally formed a coating on mineral dust particles. The carbonaceous coating observed at the particle scale on African dust was evidenced by the combined use of elemental and molecular microanalysis techniques, with the identification of an amorphous rather than crystallized carbon structure.

  16. The Structure and Properties of Pulsed dc Sputtered Nanocrystalline NbN Coatings for Proton Exchange Membrane Fuel Cell.

    PubMed

    Chun, Sung-Yong

    2016-02-01

    Niobium nitride coatings for the surface modified proton exchange membrane fuel cells with various pulse parameters have been prepared using dc (direct current) and asymmetric-bipolar pulsed dc magnetron sputtering. The pulse frequency and the duty cycle were varied from 5 to 50 kHz and 50 to 95%, respectively. The deposition rate, grain size and resistivity of pulsed dc sputtered films were decreased when the pulse frequency increased, while the nano hardness of niobium nitride films increased. We present in detail coatings (e.g., deposition rate, grain size, prefer-orientation, resistivity and hardness). Our studies show that niobium nitride coatings with superior properties can be prepared using asymmetric-bipolar pulsed dc sputtering.

  17. Alloy Films Deposited by Electroplating as Precursors for Protective Oxide Coatings on Solid Oxide Fuel Cells Metallic Interconnect Materials

    SciTech Connect

    Johnson, Christopher; Gemmen, R.S.; Cross, Caleb

    2006-10-01

    The successful development of stainless steel interconnects for intermediate temperature solid oxide fuel cells (SOFC) may be the materials breakthrough that makes SOFC technology truly commercial. Many of the ferritic stainless steels, however, suffer from a relatively high area specific resistance (ASR) after long exposure times at temperature and the Cr in the native oxide can evaporate and contaminate other cell components. Conductive coatings that resist oxide scale growth and chromium evaporation may prevent both of these problems. In the present study electrochemical deposition of binary alloys followed by oxidation of the alloy to form protective and conductive oxide layers is examined. Results are presented for the deposition of Mn/Co and Fe/Ni alloys via electroplating to form a precursor for spinel oxide coating formation. Analysis of the alloy coatings is done by SEM, EDS and XRD.

  18. The Structure and Properties of Pulsed dc Sputtered Nanocrystalline NbN Coatings for Proton Exchange Membrane Fuel Cell.

    PubMed

    Chun, Sung-Yong

    2016-02-01

    Niobium nitride coatings for the surface modified proton exchange membrane fuel cells with various pulse parameters have been prepared using dc (direct current) and asymmetric-bipolar pulsed dc magnetron sputtering. The pulse frequency and the duty cycle were varied from 5 to 50 kHz and 50 to 95%, respectively. The deposition rate, grain size and resistivity of pulsed dc sputtered films were decreased when the pulse frequency increased, while the nano hardness of niobium nitride films increased. We present in detail coatings (e.g., deposition rate, grain size, prefer-orientation, resistivity and hardness). Our studies show that niobium nitride coatings with superior properties can be prepared using asymmetric-bipolar pulsed dc sputtering. PMID:27433732

  19. Employing Synergetic Effect of Doping and Thin Film Coating to Boost the Performance of Lithium-Ion Battery Cathode Particles

    PubMed Central

    Patel, Rajankumar L.; Jiang, Ying-Bing; Choudhury, Amitava; Liang, Xinhua

    2016-01-01

    Atomic layer deposition (ALD) has evolved as an important technique to coat conformal protective thin films on cathode and anode particles of lithium ion batteries to enhance their electrochemical performance. Coating a conformal, conductive and optimal ultrathin film on cathode particles has significantly increased the capacity retention and cycle life as demonstrated in our previous work. In this work, we have unearthed the synergetic effect of electrochemically active iron oxide films coating and partial doping of iron on LiMn1.5Ni0.5O4 (LMNO) particles. The ionic Fe penetrates into the lattice structure of LMNO during the ALD process. After the structural defects were saturated, the iron started participating in formation of ultrathin oxide films on LMNO particle surface. Owing to the conductive nature of iron oxide films, with an optimal film thickness of ~0.6 nm, the initial capacity improved by ~25% at room temperature and by ~26% at an elevated temperature of 55 °C at a 1C cycling rate. The synergy of doping of LMNO with iron combined with the conductive and protective nature of the optimal iron oxide film led to a high capacity retention (~93% at room temperature and ~91% at 55 °C) even after 1,000 cycles at a 1C cycling rate. PMID:27142704

  20. Effect of Chelating Agents on the Stability of Nano-TiO2 Sol Particles for Sol-Gel Coating.

    PubMed

    Maeng, Wan Young; Yoo, Mi

    2015-11-01

    Agglomeration of sol particles in a titanium alkoxide (tetrabutyl orthotitanate (TBOT), > 97%) solution during the hydrolysis and condensation steps makes the sol solution difficult to use for synthesizing homogeneous sol-gel coating. Here, we have investigated the effect of stabilizing agents (acetic acid and ethyl acetoacetate (EAcAc)) on the agglomeration of Ti alkoxide particles during hydrolysis and condensation in order to determine the optimized conditions for controlling the precipitation of TiO2 particles. The study was conducted at R(AC) ([acetic acid]/[TBOT]) = 0.1-5 and R(EAcAc)([EAcAc]/[TBOT]) = 0.05-0.65. We also studied the effects of a basic catalyst ethanolamine (ETA), water, and HCl on sol stability. The chelating ligands in the precursor sol were analyzed with FT-IR. The coating properties were examined by focused ion beam. The stabilizing agents (acetic acid and EAcAc) significantly influenced the agglomeration and precipitation of TBOT precursor particles during hydrolysis. As R(AC) and R(EAcAc) increased, the agglomeration remarkably decreased. The stability of the sol with acetic acid and EAcAc arises from the coordination of the chelating ligand to TBOT that hinders hydrolysis and condensation. A uniform fine coating (thickness: 30 nm) on stainless steel was obtained by using an optimized sol with R(AC) = 0.5 and R(EAcAc) = 0.65.

  1. Employing Synergetic Effect of Doping and Thin Film Coating to Boost the Performance of Lithium-Ion Battery Cathode Particles

    NASA Astrophysics Data System (ADS)

    Patel, Rajankumar L.; Jiang, Ying-Bing; Choudhury, Amitava; Liang, Xinhua

    2016-05-01

    Atomic layer deposition (ALD) has evolved as an important technique to coat conformal protective thin films on cathode and anode particles of lithium ion batteries to enhance their electrochemical performance. Coating a conformal, conductive and optimal ultrathin film on cathode particles has significantly increased the capacity retention and cycle life as demonstrated in our previous work. In this work, we have unearthed the synergetic effect of electrochemically active iron oxide films coating and partial doping of iron on LiMn1.5Ni0.5O4 (LMNO) particles. The ionic Fe penetrates into the lattice structure of LMNO during the ALD process. After the structural defects were saturated, the iron started participating in formation of ultrathin oxide films on LMNO particle surface. Owing to the conductive nature of iron oxide films, with an optimal film thickness of ~0.6 nm, the initial capacity improved by ~25% at room temperature and by ~26% at an elevated temperature of 55 °C at a 1C cycling rate. The synergy of doping of LMNO with iron combined with the conductive and protective nature of the optimal iron oxide film led to a high capacity retention (~93% at room temperature and ~91% at 55 °C) even after 1,000 cycles at a 1C cycling rate.

  2. Effect of particle concentration on the structure and tribological properties of submicron particle SiC reinforced Ni metal matrix composite (MMC) coatings produced by electrodeposition

    NASA Astrophysics Data System (ADS)

    Gül, H.; Kılıç, F.; Uysal, M.; Aslan, S.; Alp, A.; Akbulut, H.

    2012-03-01

    In the present work, a nickel sulfate bath containing SiC submicron particles between 100 and 1000 nm was used as the plating electrolyte. The aim of this work is to obtain Ni-SiC metal matrix composites (MMCs) reinforced with submicron particles on steel surfaces with high hardness and wear resistance for using in anti-wear applications such as dies, tools and working parts for automobiles and vehicles. The influence of the SiC content in the electrolyte on particle distribution, microhardness and wear resistance of nano-composite coatings was studied. During the electroplating process, the proper stirring speed was also determined for sub-micron SiC deposition with Ni matrix. The Ni films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The depositions were controlled to obtain a specific thickness (between 50 and 200 μm) and volume fraction of the particles in the matrix (between 0.02 and 0.10). The hardness of the coatings was measured to be 280-571 HV depending on the particle volume in the Ni matrix. The tribological behaviors of the electrodeposited SiC nanocomposite coatings sliding against an M50 steel ball (Ø 10 mm) were examined on a tribometer. All the friction and wear tests were performed without lubrication at room temperature and in the ambient air (with a relative humidity of 55-65%). The results showed that the wear resistance of the nanocomposites was approximately 2-2.2 times more than those of unreinforced Ni.

  3. [Experimental study on particle size distributions of an engine fueled with blends of biodiesel].

    PubMed

    Lu, Xiao-Ming; Ge, Yun-Shan; Han, Xiu-Kun; Wu, Si-Jin; Zhu, Rong-Fu; He, Chao

    2007-04-01

    The purpose of this study is to obtain the particle size distributions of an engine fueled biodiesel and its blends. A turbocharged DI diesel engine was tested on a dynamometer. A pump of 80 L/min and fiber glass filters with diameter of 90 mm were used to sample engine particles in exhaust pipe. Sampling duration was 10 minutes. Particle size distributions were measured by a laser diffraction particle size analyzer. Results indicated that higher engine speed resulted in smaller particle sizes and narrower distributions. The modes on distribution curves and mode variation were larger with dry samples than with wet samples (dry: around 10 - 12 microm vs. wet: around 4 - 10 microm). At low speed, Sauter mean diameter d32 of dry samples was the biggest with B100, the smallest with diesel fuel, and among them with B20, while at high speed, d32 the biggest with B20, the smallest with B100, and in middle with diesel. Median diameter d(0.5) also reflected the results. Except for 2 000 r/min, d32 of wet with B20 is the biggest, the smallest with diesel, and in middle with B100. The large mode variation resulted in increase of d32. PMID:17639924

  4. Fuel Damage Reduction by Installation of Particle Traps in the Feedwater Lines

    SciTech Connect

    Henriksson, Mats; Westin, Johan; Lindqvist, Hans; Lundstrom, Anders; Alavyoon, Farid; Kaipainen, Tapio

    2006-07-01

    Fuel damages are commonly caused by grinding of the cladding due to debris entering the reactor pressure vessel. In order to reduce the probability for fuel damages so-called particle traps have been developed and are currently in operation in two Swedish nuclear power plants. The particle traps are of type axial centrifugal separators, and are characterized by a robust design, high separation rate and low pressure drop (typically less than 1 bar). Special care has been taken in the design of the flow straightener, which efficiently eliminates the swirl in the flow. The model tests show that the Swirl number downstream of the particle trap is typically the same order of magnitude or less than that downstream of a pipe bend. The particles are separated from the main flow and collected in a separate chamber, which is emptied only during the outages. Traps have been developed for both upward or downward flow direction, with feedwater flows from 300 to 900 kg/s. The present paper describes the development work, which is primarily based on full-scale model tests supported by CFD-calculations. Some operating experiences from plants in which particle traps currently are in use are also reported. (authors)

  5. An investigation of the microstructure and mechanical properties of electrochemically coated Ag(4)Sn dental alloy particles condensed in vitro

    NASA Astrophysics Data System (ADS)

    Marquez, Jose Antonio

    As part of the ongoing scientific effort to develop a new amalgam-like material without mercury, a team of metallurgists and electrochemists at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, announced in 1993 the development of a new Ag-Sn dental alloy system without mercury that sought to replace conventional dental amalgams. They used spherical Ag3Sn and Ag4Sn intermetallic dental alloy particles, commonly used in conventional dental alloys, and coated them with electrodeposited silver with newly-developed electrolytic and immersion techniques. The particles had relatively pure silver coatings that were closely adherent to the intermetalfic cores. These silver-coated particles, due to silver's plasticity at room temperature, were condensed into PlexiglasRTM molds with the aid of an acidic surface activating solution (HBF4) and a mechanical condensing device, producing a metal-matrix composite with Ag3,4Sn filler particles surrounded by a cold-welded silver matrix. Since silver strain hardens rather easily, the layers had to be condensed in less than 0.5 mm increments to obtain a dense structure. Mechanical testing at NIST produced compressive strength values equal to or greater than those of conventional dental amalgams. Because of its potential for eliminating mercury as a constituent in dental amalgam, this material created a stir in dental circles when first developed and conceivably could prove to be a major breakthrough in the field of dental restoratives. To date, the chief impediments to its approval for human clinical applications by the Food and Drug Administration are the potentially-toxic surface activating solution used for oxide reduction, and the high condensation pressures needed for cold welding because of the tendency for silver to strain harden. In this related study, the author, who has practiced general dentistry for 25 years, evaluates some of the mechanical and microstructural properties of these

  6. Effect of fuel injection pressure on a heavy-duty diesel engine nonvolatile particle emission.

    PubMed

    Lähde, Tero; Rönkkö, Topi; Happonen, Matti; Söderström, Christer; Virtanen, Annele; Solla, Anu; Kytö, Matti; Rothe, Dieter; Keskinen, Jorma

    2011-03-15

    The effects of the fuel injection pressure on a heavy-duty diesel engine exhaust particle emissions were studied. Nonvolatile particle size distributions and gaseous emissions were measured at steady-state engine conditions while the fuel injection pressure was changed. An increase in the injection pressure resulted in an increase in the nonvolatile nucleation mode (core) emission at medium and at high loads. At low loads, the core was not detected. Simultaneously, a decrease in soot mode number concentration and size and an increase in the soot mode distribution width were detected at all loads. Interestingly, the emission of the core was independent of the soot mode concentration at load conditions below 50%. Depending on engine load conditions, growth of the geometric mean diameter of the core mode was also detected with increasing injection pressure. The core mode emission and also the size of the mode increased with increasing NOx emission while the soot mode size and emission decreased simultaneously.

  7. The Influence of a Secondary Organic Aerosol Coating on the Heterogeneous Reaction of Squalane Particles with OH

    NASA Astrophysics Data System (ADS)

    Kolesar, K.; Cappa, C. D.; Buffaloe, G.; Chen, C. J.; Isaacman, G.; Nah, T.; Ruehl, C.; Goldstein, A. H.; Wilson, K. R.

    2012-12-01

    Reactions occurring in the condensed phase or at the surface of particles have the potential to alter their chemical and physical properties. The use of a model system such as the previously well-characterized heterogeneous oxidation of particulate squaqlane can facilitate understanding of the mechanisms associated with such reactions. The rate of squalane oxidation is determined from the frequency of hydroxyl radical collision with the particle surface and the probability that a collision will react. We now add a layer of complexity to the oxidation of particulate squalane by measuring the heterogeneous reactivity towards OH of the squalane after addition of a coating of secondary organic aerosol (SOA), generated from the reaction of α-pinene and ozone. Heterogeneous reaction rates and OH uptake coefficients for squalane within the resulting internally mixed particles were measured using a flow tube reactor coupled to the Vacuum Ultraviolet Aerosol Mass Spectrometer at Beamline 9.0.2 of the Advanced Light Source. The use of the relatively soft VUV ionization allowed for clear differentiation of squalane and its major oxidation products from that of the SOA in the measured mass spectra. This allows for direct, online measurement of the squalane decay rate in the presence of the SOA species and thus determination of the reaction rate constant for squalane with OH radicals. The decay of squalane in the internally mixed squalane/SOA particles was faster than that observed for pure squalane particles, by about a factor of 2, despite the fact that the SOA was coated onto the squalane particles. The apparent increase in the squalane loss rate is most likely due to increased loss of squalane via condensed-phase secondary chemical reactions in the mixed particles. This illustrates the important role the particle composition plays in determining the nature and extent of condensed phase reactions that occur within organic particles in the atmosphere that warrants further

  8. Chemical characterization of biomass fuel smoke particles of rural kitchens of South Asia

    NASA Astrophysics Data System (ADS)

    Deka, Pratibha; Hoque, Raza Rafiqul

    2015-05-01

    Biomass fuel smoke particles (BFSPs) of rural kitchens collected during dry and wet seasons were characterized for elements, anions and carbon. The BFSPs of kitchens using varied biomass fuel types viz. cow dung stick, mixed biomass, cow-dung stick-mixed biomass and sugarcane bagasse were chosen for the study. The BFSPs from cow dung fuel stick showed higher levels of elements, anions and particulate carbon than other BFSPs. Calcium, K, Fe and Mg were the major elements found in all BFSPs, which did not vary much between the seasons. Sulphate was found to be the dominant anion present in all BFSPs followed by Clˉ and PO43-. Seasonal variation was pronounced in the case of abundance of anions and particulate carbon. The ratio OC/EC, often used as source signature of biomass burning, was found to be within 1.89-7.41 and 1.72-6.19 during dry and wet seasons respectively.

  9. The effect of particles size distribution on aesthetic and thermal performances of polydisperse TiO2 pigmented coatings: Comparison between numerical and experimental results

    NASA Astrophysics Data System (ADS)

    Baneshi, Mehdi; Gonome, Hiroki; Komiya, Atsuki; Maruyama, Shigenao

    2012-05-01

    A new approach in designing pigmented coatings considering both visual and thermal concerns was introduced by authors in previous works. The objective was to design a pigmented coating with dark appearance which can stay cool while exposed to sunlight. This behavior can be achieved by coating a typical black substrate with a pigmented coating with controlled size and concentration of particles and coating thickness. In present work, the spectral behaviour of polydisperse TiO2 pigmented coatings was studied. The radiative properties of polydisperse TiO2 powders were evaluated and the radiative transfer in the pigmented coating was modelled using the radiation element method by ray emission model (REM2). The effects of particles size distribution on spectral reflectivity, optimization parameter, and color coordinates were discussed. The results of numerical calculation were validated by experimental reflectivity measurements of several TiO2 pigmented coating samples made from two different TiO2 powders with different size distributions of particles. The results show that our model can reasonably predict the spectral reflectivity of TiO2 pigmented coating samples. Moreover, the results of optimized monodisperse TiO2 pigmented coatings were again validated.

  10. Friction and wear properties of high-velocity oxygen fuel sprayed WC-17Co coating under rotational fretting conditions

    NASA Astrophysics Data System (ADS)

    Luo, Jun; Cai, Zhenbing; Mo, Jiliang; Peng, Jinfang; Zhu, Minhao

    2016-05-01

    Rotational fretting which exist in many engineering applications has incurred enormous economic loss. Thus, accessible methods are urgently needed to alleviate or eliminate damage by rotational fretting. Surface engineering is an effective approach that is successfully adopted to enhance the ability of components to resist the fretting damage. In this paper, using a high-velocity oxygen fuel sprayed (HVOF) technique WC-17Co coating is deposited on an LZ50 steel surface to study its properties through Vickers hardness testing, scanning electric microscope (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffractrometry (XRD). Rotational fretting wear tests are conducted under normal load varied from 10 N to 50 N, and angular displacement amplitudes vary from 0.125° to 1°. Wear scars are examined using SEM, EDX, optical microscopy (OM), and surface topography. The experimental results reveal that the WC-17Co coating adjusted the boundary between the partial slip regime (PSR) and the slip regime (SR) to the direction of smaller amplitude displacement. As a result, the coefficients of friction are consistently lower than the substrate's coefficients of friction both in the PSR and SR. The damage to the coating in the PSR is very slight. In the SR, the coating exhibits higher debris removal efficiency and load-carrying capacity. The bulge is not found for the coating due to the coating's higher hardness to restrain plastic flow. This research could provide experimental bases for promoting industrial application of WC-17Co coating in prevention of rotational fretting wear.

  11. Solubility of hot fuel particles from Chernobyl--influencing parameters for individual radiation dose calculations.

    PubMed

    Garger, Evgenii K; Meisenberg, Oliver; Odintsov, Oleksiy; Shynkarenko, Viktor; Tschiersch, Jochen

    2013-10-15

    Nuclear fuel particles of Chernobyl origin are carriers of increased radioactivity (hot particles) and are still present in the atmosphere of the Chernobyl exclusion zone. Workers in the zone may inhale these particles, which makes assessment necessary. The residence time in the lungs and the transfer in the blood of the inhaled radionuclides are crucial for inhalation dose assessment. Therefore, the dissolution of several kinds of nuclear fuel particles from air filters sampled in the Chernobyl exclusion zone was studied. For this purpose filter fragments with hot particles were submersed in simulated lung fluids (SLFs). The activities of the radionuclides (137)Cs, (90)Sr, (239+240)Pu and (241)Am were measured in the SLF and in the residuum of the fragments by radiometric methods after chemical treatment. Soluble fractions as well as dissolution rates of the nuclides were determined. The influence of the genesis of the hot particles, represented by the (137)Cs/(239+240)Pu ratio, on the availability of (137)Cs was demonstrated, whereas the dissolution of (90)Sr, (239+240)Pu and (241)Am proved to be independent of genesis. No difference in the dissolution of (137)Cs and (239+240)Pu was observed for the two applied types of SLF. Increased solubility was found for smaller hot particles. A two-component exponential model was used to describe the dissolution of the nuclides as a function of time. The results were applied for determining individual inhalation dose coefficients for the workers at the Chernobyl construction site. Greater dose coefficients for the respiratory tract and smaller coefficients for the other organs were calculated (compared to ICRP default values). The effective doses were in general lower for the considered radionuclides, for (241)Am even by one order of magnitude.

  12. Particle In-Flight and Coating Properties of Fe-Based Feedstock Materials Sprayed with Modern Thermal Spray Systems

    NASA Astrophysics Data System (ADS)

    Bobzin, Kirsten; Kopp, Nils; Warda, Thomas; Petkovic, Ivica; Schaefer, Marcel; Landes, Klaus Dieter; Forster, Guenter; Zimmermann, Stephan; Marques, Jose-Luis; Kirner, Stefan; Kauffeldt, Marina; Schein, Jochen

    2013-03-01

    New developments in the field of thermal spraying systems (increased particle velocities, enhanced process stability) are leading to improved coatings. Innovations in the field of feedstock materials are supporting this trend. The combination of both has led to a renaissance of Fe-based feedstocks. Using modern APS or HVOF systems, it is now possible to compete with classical materials for wear and corrosion applications like Ni-basis or metal-matrix composites. This study intends to give an analysis of the in-flight particle and spray jet properties achievable with two different modern thermal spraying systems using Fe-based powders. The velocity fields are measured with the Laser Doppler Anemometry. Resulting coatings are analyzed and a correlation with the particle in-flight properties is given. The experiments are accompanied by computational fluid dynamics simulations of spray jet and particle velocities, leading to a comprehensive analysis of the achievable particle properties with state-of-the-art HVOF and APS systems.

  13. Sorbent-coated diffusion denuders for direct measurement of gas/particle partitioning by semi-volatile organic compounds

    SciTech Connect

    Gundel, L.A.; Lane, D.A.

    1998-01-01

    Sorbent-coated annular denuder-based samplers have been developed for direct determination of both gaseous and particulate semi-volatile organic species. The first such sampler, the Integrated Organic Vapor/Particle Sampler, has been validated for sampling semi-volatile PAH in ambient air and environmental tobacco smoke. Multi-channel versions of the IOVPS have been used successfully for investigation of gas/particle partitioning of a variety of semi-volatile organic species in combustion source-enriched environmental chambers. Subsequent improvements have resulted in two new higher-capacity samplers, the IOGAPS and the jumbo-IOGAPS, that use the same sorbent for sampling trace organics in the ambient atmosphere for 24--48 hr periods over a wide temperature range. Construction of these new samplers began by incorporating the IOVPS coating technology onto the gas collection surfaces of the higher capacity GAP sampler. Substantial design effort aims to ensure that vapor phase components as volatile as naphthalene can be trapped efficiently and retained by the sorbent-coated surface while the particles pass through to the filter.

  14. Advanced thermal barrier coatings for operation in high hydrogen content fueled gas turbines.

    SciTech Connect

    Sampath, Sanjay

    2015-04-02

    The Center for Thermal Spray Research (CTSR) at Stony Brook University in partnership with its industrial Consortium for Thermal Spray Technology is investigating science and technology related to advanced metallic alloy bond coats and ceramic thermal barrier coatings for applications in the hot section of gasified coal-based high hydrogen turbine power systems. In conjunction with our OEM partners (GE and Siemens) and through strategic partnership with Oak Ridge National Laboratory (ORNL) (materials degradation group and high temperature materials laboratory), a systems approach, considering all components of the TBC (multilayer ceramic top coat, metallic bond coat & superalloy substrate) is being taken during multi-layered coating design, process development and subsequent environmental testing. Recent advances in process science and advanced in situ thermal spray coating property measurement enabled within CTSR has been incorporated for full-field enhancement of coating and process reliability. The development of bond coat processing during this program explored various aspects of processing and microstructure and linked them to performance. The determination of the bond coat material was carried out during the initial stages of the program. Based on tests conducted both at Stony Brook University as well as those carried out at ORNL it was determined that the NiCoCrAlYHfSi (Amdry) bond coats had considerable benefits over NiCoCrAlY bond coats. Since the studies were also conducted at different cycling frequencies, thereby addressing an associated need for performance under different loading conditions, the Amdry bond coat was selected as the material of choice going forward in the program. With initial investigations focused on the fabrication of HVOF bond coats and the performance of TBC under furnace cycle tests , several processing strategies were developed. Two-layered HVOF bond coats were developed to render optimal balance of density and surface roughness

  15. [Contribution of Particle Size and Surface Coating of Silver Nanoparticles to Its Toxicity in Marine Diatom Skeletonema costatum].

    PubMed

    Huang, Jun; Yi, Jun; Qiang, Li-yuan; Cheng, Jin-ping

    2016-05-15

    Due to the unique antibacterial properties, silver nanoparticles (AgNPs) have been widely used in commercial applications. In this study, the toxicity of three kinds of AgNPs with different sizes and surface coatings to marine diatom Skeletonema costatum (S. costatum) was studied, which was one of the dominant species in estuarine and coastal areas. All three kinds of tested AgNPs inhibited the growth of exposed S. costatum under acute exposure condition, and the order of toxicity was 10 nm-OA > 10 nm-PVP > 20 nm-PVP. Given the condition of similar particle size, oil amine surface coated AgNPs were more toxic than polyvinyl pyrrolidone (PVP) surface coated AgNPs in S. costatum in term of cytotoxicity. With the same surface coating, the toxicity of AgNPs in S. costatum was affected by its hydrodynamic diameter and exposure concentrations. When the concentration of AgNPs was less than 500 µg · L⁻¹, larger sized AgNPs showed greater toxicity; When the concentration was greater than or equal to 500 µg · L⁻¹, smaller AgNPs exhibited greater toxicity. At molecular level, 50 µg · L⁻¹ 10nm-PVP significantly upregulated expression level of 3HfcpA (P < 0.05) and significantly downregulated expression level of Dl (P < 0.05), and 500 µg · L⁻¹ 10nm-OA significantly upregulated 3HfcpA expression (P < 0.05), while 20 nm-PVP treatment group didn't show any significant change. Exposed diatom demonstrated sensitive photosynthesis response to small size and PVP coated silver nanoparticles at molecular level. This study suggested that the toxicity of AgNPs to marine microalgae was largely controlled by the particle size, surface coating, exposure medium, exposure concentration and other factors. The smaller the particle size, the greater the toxicity of AgNPs, and the particle size of AgNPs played an important role in the toxicity of AgNPs in marine diatom S. costatum.

  16. [Contribution of Particle Size and Surface Coating of Silver Nanoparticles to Its Toxicity in Marine Diatom Skeletonema costatum].

    PubMed

    Huang, Jun; Yi, Jun; Qiang, Li-yuan; Cheng, Jin-ping

    2016-05-15

    Due to the unique antibacterial properties, silver nanoparticles (AgNPs) have been widely used in commercial applications. In this study, the toxicity of three kinds of AgNPs with different sizes and surface coatings to marine diatom Skeletonema costatum (S. costatum) was studied, which was one of the dominant species in estuarine and coastal areas. All three kinds of tested AgNPs inhibited the growth of exposed S. costatum under acute exposure condition, and the order of toxicity was 10 nm-OA > 10 nm-PVP > 20 nm-PVP. Given the condition of similar particle size, oil amine surface coated AgNPs were more toxic than polyvinyl pyrrolidone (PVP) surface coated AgNPs in S. costatum in term of cytotoxicity. With the same surface coating, the toxicity of AgNPs in S. costatum was affected by its hydrodynamic diameter and exposure concentrations. When the concentration of AgNPs was less than 500 µg · L⁻¹, larger sized AgNPs showed greater toxicity; When the concentration was greater than or equal to 500 µg · L⁻¹, smaller AgNPs exhibited greater toxicity. At molecular level, 50 µg · L⁻¹ 10nm-PVP significantly upregulated expression level of 3HfcpA (P < 0.05) and significantly downregulated expression level of Dl (P < 0.05), and 500 µg · L⁻¹ 10nm-OA significantly upregulated 3HfcpA expression (P < 0.05), while 20 nm-PVP treatment group didn't show any significant change. Exposed diatom demonstrated sensitive photosynthesis response to small size and PVP coated silver nanoparticles at molecular level. This study suggested that the toxicity of AgNPs to marine microalgae was largely controlled by the particle size, surface coating, exposure medium, exposure concentration and other factors. The smaller the particle size, the greater the toxicity of AgNPs, and the particle size of AgNPs played an important role in the toxicity of AgNPs in marine diatom S. costatum. PMID:27506055

  17. Developing TiAIN Coatings for Intermediate Temperature-Solid Oxide Fuel Cell Interconnect Applications

    SciTech Connect

    Liu, X.; Johnson, C.D.; Li, C.; Xu, J.; Cross, C.

    2007-02-01

    TiN-type coatings have potential to be used as SOFC interconnect coatings SOFC because of their low resistance and high temperature stability. In this research, various (Ti,Al)N coatings were deposited on stainless steels by filtered-arc method. ASR and XRD tests were conducted on these coatings, and SEM/EDAX analysis were conducted after ASR and XRD tests. SEM/EDAX analyses show that (Ti,Al)N remains stable at temperature up to 700°C. It is also indicated that Al has beneficial effect on the stability of TiN type coatings. At 900°C, (Ti-30Al)N is fully oxidized and some of (Ti-50Al)N coating still remains as nitride. The analyses on cross-sectional samples show that these coatings are effective barrier to the Cr migration. In summary, (Ti.Al)N coatings are good candidates for the SOFC interconnect applications at 700°C. The future directions of this research are to improve the stability of these coatings by alloy-doping and to develop multi-layer coatings.

  18. Investigation of methods to produce a uniform cloud of fuel particles in a flame tube

    NASA Technical Reports Server (NTRS)

    Siegert, Clifford E.; Pla, Frederic G.; Rubinstein, Robert; Niezgoda, Thomas F.; Burns, Robert J.; Johnson, Jerome A.

    1990-01-01

    The combustion of a uniform, quiescent cloud of 30-micron fuel particles in a flame tube was proposed as a space-based, low-gravity experiment. The subject is the normal- and low-gravity testing of several methods to produce such a cloud, including telescoping propeller fans, air pumps, axial and quadrature acoustical speakers, and combinations of these devices. When operated in steady state, none of the methods produced an acceptably uniform cloud (+ or - 5 percent of the mean concentration), and voids in the cloud were clearly visible. In some cases, severe particle agglomeration was observed; however, these clusters could be broken apart by a short acoustic burst from an axially in-line speaker. Analyses and experiments reported elsewhere suggest that transient, acoustic mixing methods can enhance cloud uniformity while minimizing particle agglomeration.

  19. Effect of fuel to air ratio on Mach 0.3 burner rig hot corrosion of ZrO2-Y2O3 thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Hodge, P. E.

    1982-01-01

    A Mach 0.3 burner rig test program was conducted to determine how the fuel to air mass ratio affects the durability of ZrO2-Y2O3/Ni-16Cr-6Al-0.31Y thermal barrier coating systems in combustion products containing 5 ppm Na and 2 ppm V. As the fuel to air mass ratio was increased from 0.039 to 0.049, the durability of ZrO2-6Y2O3, ZrO2-8Y2O3 and ZrO2-12Y2O3 coatings decreased. ZrO2-8Y2O3 coatings were approximately 2X and 1.3X more durable than ZrO2-12Y2O3 and ZrO2-6Y2O3 coatings respectively at the fuel to air mass ratio of 0.039. The number of one hour cycles endured by ZrO2-8Y2O3 coatings varied from averages of 53 to 200 for the fuel to air mass ratios of 0.049 and 0.039, respectively. At the fuel to air mass ratio of 0.049, all ZrO2-Y2O3 coated specimens failed in 40 to 60 one hour cycles

  20. The improvement of corrosion resistance of fluoropolymer coatings by SiO2/poly(styrene-co-butyl acrylate) nanocomposite particles

    NASA Astrophysics Data System (ADS)

    Chen, L.; Song, R. G.; Li, X. W.; Guo, Y. Q.; Wang, C.; Jiang, Y.

    2015-10-01

    The effects of nano-silica particles on the anticorrosion properties of fluoropolymer coatings on mild steel have been investigated in this paper. In order to enhance the dispersibility of nano-silica in fluoropolymer coatings, we treated the surface of nano-silica with poly(styrene-co-butyl acrylate) (P(St-BA)). The surface grafting of P(St-BA) on the nanoparticles were detected using Fourier transform infrared spectroscopy (FT-IR), thermo gravimetric analyzer (TGA), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The surface of nanocomposite coatings and the coating-substrates bond texture were detected by FE-SEM. We also used energy-dispersive X-ray spectroscopy (EDS) to analyze whether the nanocomposite particles were added into the fluoropolymer coatings. In addition, the influences of various nanoparticles on the corrosion resistance of fluoropolymer-coated steel were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results shown that nanocomposite particles can be dispersed better in fluoropolymer coatings, and the electrochemical results clearly shown the improvement of the protective properties of the nanocomposite coatings when 4 wt.% SiO2/P(St-BA) was added to the fluoropolymer coatings.

  1. High performance electrolyte-coated anodes for low-temperature solid oxide fuel cells: Model and Experiments

    NASA Astrophysics Data System (ADS)

    Ding, Dong; Zhu, Wei; Gao, Jianfeng; Xia, Changrong

    A geometric micro-model and experiment development are presented for electrolyte-coated anodes with high performance in solid oxide fuel cells. The anodes are based on electron conducting frameworks, where fine, oxygen-ion conducting inclusions are introduced via an ion impregnation process. The model shows that the length of triple-phase-boundary (TPB) increases with the loading of the coated electrolyte, and is dependent only on the loading before a maximum loading for monolayer coverage is obtained. The maximum loading increases with the porosity of the framework. As a result, the prolonged TPB length can be achieved by increasing the porosity and the loading. In the experimental study, Ni was used as the electron conductor, and samaria-doped ceria (SDC) was employed as the electrolyte to form anode-supported single cells. The cell performance was evaluated using humidified hydrogen as the fuel. The peak power density increased with SDC loading to a maximum value and decreased when the loading was further increased. The highest peak power density of the cells whose anodes were prepared with 10, 20 and 30 wt.% pore former was 571, 631 and 723 mW cm -2, corresponding to 508, 564 and 648 mg cm -3 of SDC loading, respectively. The experimental results are in good agreement with the model prediction. Therefore, this work demonstrates theoretically and experimentally that optimization of the porosity and electrolyte loading is critical for further improving the performance of electrolyte-coated anodes.

  2. Parameter identifiability in application of soft particle electrokinetic theory to determine polymer and polyelectrolyte coating thicknesses on colloids.

    PubMed

    Louie, Stacey M; Phenrat, Tanapon; Small, Mitchell J; Tilton, Robert D; Lowry, Gregory V

    2012-07-17

    Soft particle electrokinetic models have been used to determine adsorbed nonionic polymer and polyelectrolyte layer properties on nanoparticles or colloids by fitting electrophoretic mobility data. Ohshima first established the formalism for these models and provided analytical approximations ( Ohshima, H. Adv. Colloid Interface Sci.1995, 62, 189 ). More recently, exact numerical solutions have been developed, which account for polarization and relaxation effects and require fewer assumptions on the particle and soft layer properties. This paper characterizes statistical uncertainty in the polyelectrolyte layer charge density, layer thickness, and permeability (Brinkman screening length) obtained from fitting data to either the analytical or numerical electrokinetic models. Various combinations of particle core and polymer layer properties are investigated to determine the range of systems for which this analysis can provide a solution with reasonably small uncertainty bounds, particularly for layer thickness. Identifiability of layer thickness in the analytical model ranges from poor confidence for cases with thick, highly charged coatings, to good confidence for cases with thin, low-charged coatings. Identifiability is similar for the numerical model, except that sensitivity is improved at very high charge and permeability, where polarization and relaxation effects are significant. For some poorly identifiable cases, parameter reduction can reduce collinearity to improve identifiability. Analysis of experimental data yielded results consistent with expectations from the simulated theoretical cases. Identifiability of layer charge density and permeability is also evaluated. Guidelines are suggested for evaluation of statistical confidence in polymer and polyelectrolyte layer parameters determined by application of the soft particle electrokinetic theory.

  3. Development of Processing Windows for HVOF Carbide-Based Coatings

    NASA Astrophysics Data System (ADS)

    Ang, Andrew Siao Ming; Howse, Hugo; Wade, Scott A.; Berndt, Christopher C.

    2016-01-01

    Optimized processing windows for spraying high-quality metal carbide-based coatings are developed using particle diagnostic technology. The cermet coatings were produced via the high-velocity oxygen fuel (HVOF) spray process and are proposed for service applications such as marine hydraulics. The traditional "trial and error" method for developing coating process parameters is not technically robust, as well as being costly and time consuming. Instead, this contribution investigated the use of real-time monitoring of parameters associated with the HVOF flame jets and particles using in-flight particle diagnostics. Subsequently, coatings can be produced with knowledge concerning the molten particle size, temperature, and velocity profile. The analytical results allow identification of optimized coating process windows, which translate to coatings of lower porosity and improved mechanical performance.

  4. Single particle refuse-derived fuel devolatilization: Experimental measurements of reaction products

    SciTech Connect

    Lai, Weichuan; Krieger-Brockett, B. . Dept. of Chemical Engineering)

    1993-11-01

    The authors present experimentally measured devolatilization product yields from single particles of refuse-derived fuel (RDF), a more uniform, transportable municipal solid waste. Disposal costs and environmental concerns have stimulated interest in thermochemical conversion of this material to chemicals and fuels. The composition, reaction conditions, and particle properties were systematically varied over the range found in practice to develop quantitative measures that rank the process controllables' influence on altering the product slate. Specialized regression methods and experimental designs enhanced the accuracy in view of the feed heterogeneity and offer a general method to extract real effects from experimental and sample noise''. The results have been verified successfully using actual commercial RDF and fabricated compositions that surpass those normally found in municipal waste to anticipate the influence of trends in recycling. The results show that the reaction conditions have a greater influence on altering fuel utilization and the relative yields of char, condensibles, and gases than does the composition over the range found in MSW and RDF.

  5. Effect of TiO2 Particles on Micro-Hardness Corrosion, Wear and Friction of Ni-P-TiO2 Composite Coatings at Different Annealing Temperatures

    NASA Astrophysics Data System (ADS)

    Gadhari, Prasanna; Sahoo, Prasanta

    2016-09-01

    The present study investigates the effect of titania particles on the micro-hardness, wear resistance, corrosion resistance and friction of electroless Ni-P-TiO2 composite coatings deposited on mild steel substrates at different annealing temperatures. The experimental results confirmed that the amount of TiO2 particles incorporated in the coatings increases with increase in the concentration of particles in the electroless bath. In presence of TiO2 particles, hardness, wear resistance and corrosion resistance of the coating improve significantly. At higher annealing temperature, wear resistance increases due to formation of hard Ni3P phase and incorporation of titania particles in the coated layer. Charge transfer resistance and corrosion current density of the coatings reduce with an increase in TiO2 particles, whereas corrosion potential increases. Microstructure changes and composition of the composite coating due to heat treatment are studied with the help of scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA) and X-ray diffraction (XRD) analysis.

  6. Ethylene glycol assisted preparation of Ti(4+)-modified polydopamine coated magnetic particles with rough surface for capture of phosphorylated proteins.

    PubMed

    Ma, Xiangdong; Ding, Chun; Yao, Xin; Jia, Li

    2016-07-27

    The reversible protein phosphorylation is very important in regulating almost all aspects of cell life, while the enrichment of phosphorylated proteins still remains a technical challenge. In this work, polydopamine (PDA) modified magnetic particles with rough surface (rPDA@Fe3O4) were synthesized by introduction of ethylene glycol in aqueous solution. The PDA coating possessing a wealth of catechol hydroxyl groups could serve as an active medium to immobilize titanium ions through the metal-catechol chelation, which makes the fabrication of titanium ions modified rPDA@Fe3O4 particles (Ti(4+)-rPDA@Fe3O4) simple and very convenient. The spherical Ti(4+)-rPDA@Fe3O4 particles have a surface area of 37.7 m(2) g(-1) and superparamagnetism with a saturation magnetization value of 38.4 emu g(-1). The amount of Ti element in the particle was measured to be 3.93%. And the particles demonstrated good water dispersibility. The particles were used as adsorbents for capture of phosphorylated proteins and they demonstrated affinity and specificity for phosphorylated proteins due to the specific binding sites (Ti(4+)). Factors affecting the adsorption of phosphorylated proteins on Ti(4+)-rPDA@Fe3O4 particles were investigated. The adsorption capacity of Ti(4+)-rPDA@Fe3O4 particles for κ-casein was 1105.6 mg g(-1). Furthermore, the particles were successfully applied to isolate phosphorylated proteins in milk samples, which demonstrated that Ti(4+)-rPDA@Fe3O4 particles had potential application in selective separation of phosphorylated proteins.

  7. Effect of Neutron Absorbers Mixed in or Coating the Fuel of a 1-MWt Lithium-Cooled Space Reactor

    SciTech Connect

    Amiri, Benjamin W.; Poston, David I.

    2005-02-06

    The goal of this study was to determine the effect of various neutron poisons (boron, dysprosium, erbium, and gadolinium) on a 1-MWt, lithium-cooled liquid-metal reactor. The isotopes were considered to be in-fuel poisons, as well as poisons coating the fuel. One way to quantify the effectiveness of a poison in meeting accident-condition requirements is by defining the safety margin as the difference between keff at the beginning of life and keff during the accident scenarios. The isotope that showed the most potential in increasing the safety margin for the wet-sand/water case was 157Gd. The safety margin was 10%-20% greater using 157Gd as an in-fuel poison as opposed to a coating, depending on the poison quantity. However, the most limiting condition (i.e., the accident scenario with the highest keff, thus the lowest safety margin) is when the reactor is submerged in wet sand. None of the isotopes considered significantly affected the safety margin for the dry-sand case. However, the poison isotopes considered may have applicability for meeting the wet-sand/water keff requirements or as burnable poisons in a moderated system. The views expressed in this document are those of the author and do not necessarily reflect agreement by the government.

  8. Co/LaCrO 3 composite coatings for AISI 430 stainless steel solid oxide fuel cell interconnects

    NASA Astrophysics Data System (ADS)

    Shaigan, Nima; Ivey, Douglas G.; Chen, Weixing

    Rapidly decreasing electronic conductivity, chromium volatility and poisoning of the cathode material are the major problems associated with inevitable growth of chromia on ferritic stainless steel interconnects of solid oxide fuel cells (SOFC). This work evaluates the performance of a novel, electrodeposited composite Co/LaCrO 3 coating for AISI 430 stainless steel. The oxidation behaviour of the Co/LaCrO 3-coated AISI 430 substrates is studied in terms of scale microstructure and growth kinetics. Area-specific resistance (ASR) of the coated substrates has also been tested. The results showed that the Co/LaCrO 3 coating forms a triple-layer scale consisting of a chromia-rich subscale, a Co-Fe spinel mid-layer and a Co 3O 4 spinel top layer at 800 °C in air. This scale is protective, acts as an effective barrier against chromium migration into the outer oxide layer and exhibits a low, stable ASR of ∼0.02 Ω cm 2 after 900 h at 800 °C in air.

  9. Deposition kinetics of quantum dots and polystyrene latex nanoparticles onto alumina: role of water chemistry and particle coating.

    PubMed

    Quevedo, Ivan R; Olsson, Adam L J; Tufenkji, Nathalie

    2013-03-01

    A clear understanding of the factors controlling the deposition behavior of engineered nanoparticles (ENPs), such as quantum dots (QDs), is necessary for predicting their transport and fate in natural subsurface environments and in water filtration processes. A quartz crystal microbalance with dissipation monitoring (QCM-D) was used to study the effect of particle surface coatings and water chemistry on the deposition of commercial QDs onto Al2O3. Two carboxylated QDs (CdSe and CdTe) with different surface coatings were compared with two model nanoparticles: sulfate-functionalized (sPL) and carboxyl-modified (cPL) polystyrene latex. Deposition rates were assessed over a range of ionic strengths (IS) in simple electrolyte (KCl) and in electrolyte supplemented with two organic molecules found in natural waters; namely, humic acid and rhamnolipid. The Al2O3 collector used here is selected to be representative of oxide patches found on the surface of aquifer or filter grains. Deposition studies showed that ENP deposition rates on bare Al2O3 generally decreased with increasing salt concentration, with the exception of the polyacrylic-acid (PAA) coated CdTe QD which exhibited unique deposition behavior due to changes in the conformation of the PAA coating. QD deposition rates on bare Al2O3 were approximately 1 order of magnitude lower than those of the polystyrene latex nanoparticles, likely as a result of steric stabilization imparted by the QD surface coatings. Adsorption of humic acid or rhamnolipid on the Al2O3 surface resulted in charge reversal of the collector and subsequent reduction in the deposition rates of all ENPs. Moreover, the ratio of the two QCM-D output parameters, frequency and dissipation, revealed key structural information of the ENP-collector interface; namely, on bare Al2O3, the latex particles were rigidly attached as compared to the more loosely attached QDs. This study emphasizes the importance of considering the nature of ENP coatings as well

  10. Trace gas and particle emissions from fires in large diameter and belowground biomass fuels

    NASA Astrophysics Data System (ADS)

    Bertschi, Isaac; Yokelson, Robert J.; Ward, Darold E.; Babbitt, Ron E.; Susott, Ronald A.; Goode, Jon G.; Hao, Wei Min

    2003-07-01

    We adopt a working definition of residual smoldering combustion (RSC) as biomass combustion that produces emissions that are not lofted by strong fire-induced convection. RSC emissions can be produced for up to several weeks after the passage of a flame front and they are mostly unaffected by flames. Fuels prone to RSC include downed logs, duff, and organic soils. Limited observations in the tropics and the boreal forest suggest that RSC is a globally significant source of emissions to the troposphere. This source was previously uncharacterized. We measured the first emission factors (EF) for RSC in a series of laboratory fires and in a wooded savanna in Zambia, Africa. We report EFRSC for both particles with diameter <2.5 μm (PM2.5) and the major trace gases as measured by open-path Fourier transform infrared (OP-FTIR) spectroscopy. The major trace gases include carbon dioxide, carbon monoxide, methane, ethane, ethene, acetylene, propene, formaldehyde, methanol, acetic acid, formic acid, glycolaldehyde, phenol, furan, ammonia, and hydrogen cyanide. We show that a model used to predict trace gas EF for fires in a wide variety of aboveground fine fuels fails to predict EF for RSC. For many compounds, our EF for RSC-prone fuels from the boreal forest and wooded savanna are very different from the EF for the same compounds measured in fire convection columns above these ecosystems. We couple our newly measured EFRSC with estimates of fuel consumption by RSC to refine emission estimates for fires in the boreal forest and wooded savanna. We find some large changes in estimates of biomass fire emissions with the inclusion of RSC. For instance, the wooded savanna methane EF increases by a factor of 2.5 even when RSC accounts for only 10% of fuel consumption. This shows that many more measurements of fuel consumption and EF for RSC are needed to improve estimates of biomass burning emissions.

  11. Surfactant effect on functionalized carbon nanotube coated snowman-like particles and their electro-responsive characteristics

    SciTech Connect

    Zhang, Ke; Liu, Ying Dan; Choi, Hyoung Jin

    2012-10-15

    The core–shell structured snowman-like (SL) microparticles coated by functionalized multi-walled carbon nanotube (MWNT) were prepared in the presence of different surfactants including cationic surfactant-cetyl trimethylammonium bromide (CTAB) and anionic surfactant-sodium lauryl sulfate (SDS). The effect of surfactants on adsorption onto SL particles was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and conductivity. The cationic surfactant is found to be more effective than anionic surfactant for helping nanotube adsorbed onto microparticle due to the presence of electrostatic interaction between the functionalized MWNT and the surfactant. Furthermore, the MWNT/SL particles dispersed in silicone oil exhibited a typical fibril structure of the electrorheological characteristics under an applied electric field observed by an optical microscope (OM), in which the state of nanotubes wrapped on the particles strongly affects their electro-responsive characteristics.

  12. Coating compositions for solar selective absorption comprising a thermosetting acrylic resin and particles of a low molecular weight fluorocarbon polymer

    SciTech Connect

    Maki, M.; Fukuda, H.; Sano, S.

    1984-01-17

    A coating composition for solar selective absorption comprising, in solvent, particles of an inorganic black pigment dispersed in a dissolved binder of a thermosetting acrylic resin and particles of a low molecular weight fluorocarbon resin contained in an amount of 5-15 parts by weight per 100 parts by weight of the acrylic resin. The inorganic black particles have a size of 0.01-0.5 microns and are contained in an amount of 45-65 parts by weight per 100 parts by weight of the acrylic resin. An article having a metal substrate and a paint film formed thereon from the composition in a dry thickness of 1.5 microns or more is also described.

  13. Mechanisms Underpinning Degradation of Protective Oxides and Thermal Barrier Coatings in High Hydrogen Content (HHC) - Fueled Turbines

    SciTech Connect

    Mumm, Daniel

    2013-08-31

    The overarching goal of this research program has been to evaluate the potential impacts of coal-derived syngas and high-hydrogen content fuels on the degradation of turbine hot-section components through attack of protective oxides and thermal barrier coatings. The primary focus of this research program has been to explore mechanisms underpinning the observed degradation processes, and connections to the combustion environments and characteristic non-combustible constituents. Based on the mechanistic understanding of how these emerging fuel streams affect materials degradation, the ultimate goal of the program is to advance the goals of the Advanced Turbine Program by developing materials design protocols leading to turbine hot-section components with improved resistance to service lifetime degradation under advanced fuels exposures. This research program has been focused on studying how: (1) differing combustion environments – relative to traditional natural gas fired systems – affect both the growth rate of thermally grown oxide (TGO) layers and the stability of these oxides and of protective thermal barrier coatings (TBCs); and (2) how low levels of fuel impurities and characteristic non-combustibles interact with surface oxides, for instance through the development of molten deposits that lead to hot corrosion of protective TBC coatings. The overall program has been comprised of six inter-related themes, each comprising a research thrust over the program period, including: (i) evaluating the role of syngas and high hydrogen content (HHC) combustion environments in modifying component surface temperatures, heat transfer to the TBC coatings, and thermal gradients within these coatings; (ii) understanding the instability of TBC coatings in the syngas and high hydrogen environment with regards to decomposition, phase changes and sintering; (iii) characterizing ash deposition, molten phase development and infiltration, and associated corrosive

  14. Cross-linked silicone coating: a novel prefilled syringe technology that reduces subvisible particles and maintains compatibility with biologics.

    PubMed

    Depaz, Roberto A; Chevolleau, Tzvetelina; Jouffray, Sébastien; Narwal, Roja; Dimitrova, Mariana N

    2014-05-01

    Prefilled syringes (PFSs) offer improvements in the delivery of drugs to patients compared with traditional vial presentations and are becoming necessities in an increasingly competitive biologics market. However, the development of a product in a PFS must take into account potential incompatibilities between the drug and the components of the syringe. One such component is silicone oil, which has previously been suggested to promote protein aggregation, loss of soluble protein, and an increase in the particulate content of injectable formulations. This study evaluated the particulate content in a model buffer system (polysorbate 80/phosphate-buffered saline) after agitation in glass syringes with a novel cross-linked silicone coating. We also evaluated the compatibility of two monoclonal antibodies with these syringes. We report that syringes with this novel coating, compared with standard siliconized syringes, exhibited reduced particle content and enhanced integrity of the lubricant layer as determined by reflectometry, optical microscopy, and time-of-flight secondary ion mass spectrometry measurements, while