Effect of polyoxyethylene sorbitan esters and sodium caseinate on physicochemical properties of palm-based functional lipid nanodispersions.

PubMed

Cheong, Jean Ne; Mirhosseini, Hamed; Tan, Chin Ping

2010-06-01

The main objective of the present study was to investigate the effect of polyoxyethylene sorbitan esters and sodium caseinate on physicochemical properties of palm-based functional lipid nanodispersions prepared by the emulsification-evaporation technique. The results indicated that the average droplet size increased significantly (P < 0.05) by increasing the chain length of fatty acids and also by increasing the hydrophile-lipophile balance value. Among the prepared nanodispersions, the nanoemulsion containing Polysorbate 20 showed the smallest average droplet size (202 nm) and narrowest size distribution for tocopherol-tocotrienol nanodispersions, while sodium caseinate-stabilized nanodispersions containing carotenoids had the largest average droplet size (386 nm), thus indicating a greater emulsifying role for Polysorbate 20 compared with sodium caseinate.

Solid‐in‐oil nanodispersions for transdermal drug delivery systems

PubMed Central

Kitaoka, Momoko; Wakabayashi, Rie; Kamiya, Noriho

2016-01-01

Abstract Transdermal administration of drugs has advantages over conventional oral administration or administration using injection equipment. The route of administration reduces the opportunity for drug evacuation before systemic circulation, and enables long‐lasting drug administration at a modest body concentration. In addition, the skin is an attractive route for vaccination, because there are many immune cells in the skin. Recently, solid‐in‐oil nanodisperison (S/O) technique has demonstrated to deliver cosmetic and pharmaceutical bioactives efficiently through the skin. S/O nanodispersions are nanosized drug carriers designed to overcome the skin barrier. This review discusses the rationale for preparation of efficient and stable S/O nanodispersions, as well as application examples in cosmetic and pharmaceutical materials including vaccines. Drug administration using a patch is user‐friendly, and may improve patient compliance. The technique is a potent transcutaneous immunization method without needles. PMID:27529824

Characterization and durability testing of plasma-sprayed zirconia-yttria and hafnia-yttria thermal barrier coatings. Part 2: Effect of spray parameters on the performance of several hafnia-yttria and zirconia-yttria coatings

NASA Technical Reports Server (NTRS)

Miller, Robert A.; Leissler, George W.

1993-01-01

This is the second of two reports which discuss initial experiments on thermal barrier coatings prepared and tested in newly upgraded plasma spray and burner rig test facilities at LeRC. The first report, part 1, describes experiments designed to establish the spray parameters for the baseline zirconia-yttria coating. Coating quality was judged primarily by the response to burner rig exposure, together with a variety of other characterization approaches including thermal diffusivity measurements. That portion of the study showed that the performance of the baseline NASA coating was not strongly sensitive to processing parameters. In this second part of the study, new hafnia-yttria coatings were evaluated with respect to both baseline and alternate zirconia-yttria coatings. The hafnia-yttria and the alternate zirconia-yttria coatings were very sensitive to plasma-spray parameters in that high-quality coatings were obtained only when specific parameters were used. The reasons for this important observation are not understood.

Solid-in-oil nanodispersions for transdermal drug delivery systems.

PubMed

Kitaoka, Momoko; Wakabayashi, Rie; Kamiya, Noriho; Goto, Masahiro

2016-11-01

Transdermal administration of drugs has advantages over conventional oral administration or administration using injection equipment. The route of administration reduces the opportunity for drug evacuation before systemic circulation, and enables long-lasting drug administration at a modest body concentration. In addition, the skin is an attractive route for vaccination, because there are many immune cells in the skin. Recently, solid-in-oil nanodisperison (S/O) technique has demonstrated to deliver cosmetic and pharmaceutical bioactives efficiently through the skin. S/O nanodispersions are nanosized drug carriers designed to overcome the skin barrier. This review discusses the rationale for preparation of efficient and stable S/O nanodispersions, as well as application examples in cosmetic and pharmaceutical materials including vaccines. Drug administration using a patch is user-friendly, and may improve patient compliance. The technique is a potent transcutaneous immunization method without needles. © 2016 The Authors. Biotechnology Journal published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Paramagnetic Defects in Electron-Irradiated Yttria-Stabilized Zirconia: Effect of Yttria Content

DOE Office of Scientific and Technical Information (OSTI.GOV)

Costantini, Jean-Marc; Beuneu, Francois; Morrison-Smith, Sarah

2011-01-01

We have studied the effect of the yttria content on the paramagnetic centres in electron-irradiated yttria-stabilized zirconia (ZrO2: Y3+) or YSZ. Single crystals with 9.5 mol% or 18 mol% Y2O3 were irradiated with electrons of 1.0, 1.5, 2.0 and 2.5 MeV. The paramagnetic centre production was studied by X-band EPR spectroscopy. The same paramagnetic centres were identified for both chemical compositions, namely two electron centres, i.e. i) F+-type centres (involving singly ionized oxygen vacancies), and ii) so-called T centres (Zr3+ in a trigonal symmetry site), and hole-centres. A strong effect is observed on the production of hole-centres which are stronglymore » enhanced when doubling the yttria content. However, no striking effect is found on the electron centres (except the enhancement of an extra line associated to the F+-type centres). It is concluded that hole-centres are produced by inelastic interactions, whereas F+-type centres are produced by elastic collisions with no effect of the yttria content on the defect production rate. In the latter case, the threshold displacement energy (Ed) of oxygen is estimated from the electron-energy dependence of the F+-type centre production rate, with no significant effect of the yttria content on Ed. An Ed value larger than 120 eV is found. Accordingly, classical molecular dynamics (MD) simulations with a Buckingham-type potential show that Ed values for Y and O are likely to be in excess of 200 eV. Due to the difficulty in displacing O or Y atoms, the radiation-induced defects may alternatively be a result of Zr atom displacements for Ed = 80 1 eV with subsequent defect re-arrangement.« less

Dehydration and crystallization kinetics of zirconia-yttria gels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramanathan, S.; Muraleedharan, R.V.; Roy, S.K.

1995-02-01

Zirconia and zirconia-yttria gels containing 4 and 8 mol% yttria were obtained by coprecipitation and drying at 373 K. The dehydration and crystallization behavior of the dried gels was studied by DSC, TG, and XRD. The gels undergo elimination of water over a wide temperature range of 373--673 K. The peak temperature of the endotherm corresponding to dehydration and the kinetic constants for the process were not influenced by the yttria content of the gel. The enthalpy of dehydration observed was in good agreement with the heat of vaporization data. The dehydration was followed by a sharp exothermic crystallization process.more » The peak temperature of the exotherm and the activation energy of the process increased with an increase in yttria content, while the enthalpy of crystallization showed a decrease. The ``glow effect`` reduced with increasing yttria content. Pure zirconia crystallizes in the tetragonal form while the zirconia containing 4 and 8 mol% yttria appears to crystallize in the cubic form.« less

Nano-Disperse Borides and Carbides: Plasma Technology Production, Specific Properties, Economic Evaluation

NASA Astrophysics Data System (ADS)

Galevskii, G. V.; Rudneva, V. V.; Galevskii, S. G.; Tomas, K. I.; Zubkov, M. S.

2016-04-01

The experience of production and study on properties of nano-disperse chromium and titanium borides and carbides, and silicon carbide has been generalized. The structure and special service aspects of utilized plasma-metallurgical complex equipped with a three-jet direct-flow reactor with a capacity of 150 kW have been outlined. Processing, heat engineering and service life characteristics of the reactor are specified. The synthesis parameters of borides and carbides, as well as their basic characteristics in nano-disperse condition and their production flow diagram are outlined. Engineering and economic performance of synthesizing borides in laboratory and industrial conditions is assessed, and the respective segment of the international market as well. The work is performed at State Siberian Industrial University as a project part of the State Order of Ministry of Science and Education of the Russian Federation No. 11.1531/2014/K.

Paramagnetic defects in electron-irradiated yttria-stabilized zirconia: Effect of yttria content

DOE Office of Scientific and Technical Information (OSTI.GOV)

Costantini, Jean-Marc; Beuneu, Francois; Morrison-Smith, Sarah E.

2011-12-20

We have studied the effect of the yttria content on the paramagnetic centres in electron-irradiated yttria-stabilized zirconia (ZrO2: Y3+) or YSZ. Single crystals with 9.5 mol% or 18 mol% Y2O3 were irradiated with electrons of 1.0, 1.5, 2.0 and 2.5 MeV. The paramagnetic centre production was studied by X-band EPR spectroscopy. The same paramagnetic centres were identified for both chemical compositions, namely two electron centres, i.e. i) F+-type centres (involving singly ionized oxygen vacancies), and ii) so-called T centres (Zr3+ in a trigonal symmetry site), and hole-centres. A strong effect is observed on the production of hole-centres which are stronglymore » enhanced when doubling the yttria content. However, no striking effect is found on the electron centres (except the enhancement of an extra line associated to the F+-type centres). It is concluded that hole-centres are produced by inelastic interactions, whereas F+-type centres are produced by elastic collisions with no effect of the yttria content on the defect production rate. In the latter case, the threshold displacement energy (Ed) of oxygen is estimated from the electron-energy dependence of the F+-type centre production rate, with no significant effect of the yttria content on Ed. An Ed value larger than 120 eV is found. Accordingly, classical molecular dynamics (MD) simulations with a Buckingham-type potential show that Ed values for Y and O are likely to be in excess of 200 eV. It is concluded that F+-type centres might be actually oxygen divacancies (F2+-type centres). Due to the difficulty in displacing O or Y atoms, the radiation-induced defects may alternatively be a result of Zr atom displacements for Ed = 80 ± 1 eV with subsequent defect re-arrangement.« less

Scandia-and-Yttria-Stabilized Zirconia for Thermal Barriers

NASA Technical Reports Server (NTRS)

Mess, Derek

2003-01-01

yttria in suitable proportions has shown promise of being a superior thermal- barrier coating (TBC) material, relative to zirconia stabilized with yttria only. More specifically, a range of compositions in the zirconia/scandia/yttria material system has been found to afford increased resistance to deleterious phase transformations at temperatures high enough to cause deterioration of yttria-stabilized zirconia. Yttria-stabilized zirconia TBCs have been applied to metallic substrates in gas turbine and jet engines to protect the substrates against high operating temperatures. These coatings have porous and microcracked structures, which can accommodate strains induced by thermal-expansion mismatch and thermal shock. The longevity of such a coating depends upon yttria as a stabilizing additive that helps to maintain the zirconia in an yttria-rich, socalled non-transformable tetragonal crystallographic phase, thus preventing transformation to the monoclinic phase with an associated deleterious volume change. However, at a temperature greater than about 1,200 C, there is sufficient atomic mobility that the equilibrium, transformable zirconia phase is formed. Upon subsequent cooling, this phase transforms to the monoclinic phase, with an associated volume change that adversely affects the integrity of the coating. Recently, scandia was identified as a stabilizer that could be used instead of, or in addition to, yttria. Of particular interest are scandia-and-yttria-stabilized zirconia (SYSZ) compositions of about 6 mole percent scandia and 1 mole percent yttria, which have been found to exhibit remarkable phase stability at a temperature of 1,400 C in simple aging tests. Unfortunately, scandia is expensive, so that the problem becomes one of determining whether there are compositions with smaller proportions of scandia that afford the required high-temperature stability. In an attempt to solve this problem, experiments were performed on specimens made with reduced

Synthesis and thermal stability of zirconia and yttria-stabilized zirconia microspheres.

PubMed

Leib, Elisabeth W; Vainio, Ulla; Pasquarelli, Robert M; Kus, Jonas; Czaschke, Christian; Walter, Nils; Janssen, Rolf; Müller, Martin; Schreyer, Andreas; Weller, Horst; Vossmeyer, Tobias

2015-06-15

Zirconia microparticles produced by sol-gel synthesis have great potential for photonic applications. To this end, identifying synthetic methods that yield reproducible control over size uniformity is important. Phase transformations during thermal cycling can disintegrate the particles. Therefore, understanding the parameters driving these transformations is essential for enabling high-temperature applications. Particle morphology is expected to influence particle processability and stability. Yttria-doping should improve the thermal stability of the particles, as it does in bulk zirconia. Zirconia and YSZ particles were synthesized by improved sol-gel approaches using fatty acid stabilizers. The particles were heated to 1500 °C, and structural and morphological changes were monitored by SEM, ex situ XRD and high-energy in situ XRD. Zirconia particles (0.4-4.3 μm in diameter, 5-10% standard deviation) synthesized according to the modified sol-gel approaches yielded significantly improved monodispersities. As-synthesized amorphous particles transformed to the tetragonal phase at ∼450 °C with a volume decrease of up to ∼75% and then to monoclinic after heating from ∼650 to 850 °C. Submicron particles disintegrated at ∼850 °C and microparticles at ∼1200 °C due to grain growth. In situ XRD revealed that the transition from the amorphous to tetragonal phase was accompanied by relief in microstrain and the transition from tetragonal to monoclinic was correlated with the tetragonal grain size. Early crystallization and smaller initial grain sizes, which depend on the precursors used for particle synthesis, coincided with higher stability. Yttria-doping reduced grain growth, stabilized the tetragonal phase, and significantly improved the thermal stability of the particles. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Coatings Based on Nanodispersed Oxide Materials Produced by the Method of Pneumatic Spraying

NASA Astrophysics Data System (ADS)

Potekaev, A. I.; Lysak, I. A.; Malinovskaya, T. D.; Lysak, G. V.

2018-03-01

New approaches are proposed, relying on which the coatings from nanodispersed oxide materials are formed on polypropylene fibers. It is shown that in the course of the viscous fluid - solid state transition of the polymer its nanoparticles are stabilized on the surface of the formed fibers.

Characteristics of nano-sized yttria powder synthesized by a polyvinyl alcohol solution route at low temperature.

PubMed

Lee, Sang-Jin; Jung, Choong-Hwan

2012-01-01

Nano-sized yttria (Y2O3) powders were successfully synthesized at a low temperature of 400 degrees C by a simple polymer solution route. PVA polymer, as an organic carrier, contributed to an atom-scale homogeneous precursor gel and it resulted in fully crystallized, nano-sized yttria powder with high specific surface area through the low temperature calcination. In this process, the content of PVA, calcination temperature and heating time affected the microstructure and crystallization behavior of the powders. The development of crystalline phase and the final particle size were strongly dependant on the oxidation reaction from the polymer burn-out step and the PVA content. In this paper, the PVA solution technique for the fabrication of nano-sized yttria powders is introduced. The effects of PVA content and holding time on the powder morphology and powder specific surface area are also studied. The characterization of the synthesized powders is examined by using XRD, DTA/TG, SEM, TEM and nitrogen gas adsorption. The yttria powder synthesized from the PVA content of 3:1 ratio and calcined at 400 degrees C had a crystallite size of about 20 nm or less with a high surface areas of 93.95-120.76 m2 g(-1).

Characterization and durability testing of plasma-sprayed zirconia-yttria and hafnia-yttria thermal barrier coatings. Part 1: Effect of spray parameters on the performance of several lots of partially stabilized zirconia-yttria powder

NASA Technical Reports Server (NTRS)

Miller, Robert A.; Leissler, George W.; Jobe, J. Marcus

1993-01-01

Initial experiments conducted on thermal barrier coatings prepared in the newly upgraded research plasma spray facility and the burner rig test facilities are discussed. Part 1 discusses experiments which establish the spray parameters for three baseline zirconia-yttria coatings. The quality of five similar coating lots was judged primarily by their response to burner rig exposure supplemented by data from other sources such as specimen characterizations and thermal diffusivity measurements. After allowing for burner rig variability, although there appears to be an optimum density (i.e., optimum microstructure) for maximum burner rig life, the distribution tends to be rather broad about the maximum. In Part 2, new hafnia-yttria-based coatings were evaluated against both baseline and alternate zirconia-yttria coatings. The hafnia-yttria coatings and the zirconia-yttria coatings that were prepared by an alternate powder vendor were very sensitive to plasma spray parameters, in that high-quality coatings were only obtained when certain parameters were employed. The reasons for this important observation are not understood. Also not understood is that the first of two replicate specimens sprayed for Part 1 consistently performed better than the second specimen. Subsequent experiments did not display this spray order affect, possibly because a chiller was installed in the torch cooling water circuit. Also, large changes in coating density were observed after switching to a new lot of electrodes. Analyses of these findings were made possible, in part, because of the development of a sensitive density measurement technique described herein in detail. The measured thermal diffusivities did not display the expected strong relationship with porosity. This surprising result was believed to have been caused by increased microcracking of the denser coatings on the stainless steel substrates.

Subsurface segregation of yttria in yttria stabilized zirconia

NASA Astrophysics Data System (ADS)

de Ridder, M.; van Welzenis, R. G.; van der Gon, A. W. Denier; Brongersma, H. H.; Wulff, S.; Chu, W.-F.; Weppner, W.

2002-09-01

The segregation behavior in 3 and 10 mol % polycrystalline yttria stabilized zirconia (YSZ), calcined at temperatures ranging from 300 to 1600 degC, is characterized using low-energy ion scattering (LEIS). In order to be able to separate the Y and Zr LEIS signals, YSZ samples have been prepared using isotopically enriched 94ZrO2 instead of natural zirconia. The samples are made via a special precipitation method at a low temperature. The segregation to the outermost surface layer is dominated by impurities. The increased impurity levels are restricted to this first layer, which underlines the importance of the use of LEIS for this study. For temperatures of 1000 degC and higher, the oxides of the impurities Na, Si, and Ca even cover the surface completely. The performance of a device like the solid oxide fuel cell which has an YSZ electrolyte and a working temperature around 1000 degC, will, therefore, be strongly hampered by these impurities. The reduction of impurities, to prevent accumulation at the surface, will only be effective if the total impurity bulk concentration can be reduced below the 10 ppm level. Due to the presence of the impurities, yttria cannot accumulate in the outermost layer. It does so, in contrast to the general belief, in the subsurface layer and to much higher concentrations than the values reported previously. The difference in the interfacial free energies of Y2O3 and ZrO2 is determined to be -21plus-or-minus3 kJ/mol.

[Effects of colorants on yttria stabilized tetragonal zirconia polycrystals powder].

PubMed

Wang, Bo; Chen, Jianfeng; Zhang, Yanchun; Wang, Ru

2015-10-01

To evaluate the effect of Fe2O3 and CeO2 as colorants on yttria stabilized tetragonal zirconia poly-crystals (Y-TZP) powder. The spray granulation slurry of colored zirconia was prepared with different concentrations of Fe2O3 (0.15%) and CeO2 (4%), which were added in Y-TZP. Zirconia powder was made by spray granulation. The powder specimens were divided into three groups: uncolored zirconia, Fe2O3 (0.15%) zirconia, and CeO2 (4%) zirconia. The particle morphologies of the powder specimens were measured with a laser particle size analyzer and an optical microscope. The differences in D50 among the three groups were statistically significant (P<0.05). Group Fe2O3 showed a significant difference from groups CeO2 and uncolored zirconia (P<0.05). Group uncolored zirconia showed no significant difference from group CeO2 (P>0.05). Mostly spherical powder was observed in the three groups. Fe2O3 as a colorant can affect particles, whereas CeO2 has no effect.

High strength yttria-reinforced HA scaffolds fabricated via honeycomb ceramic extrusion.

PubMed

Elbadawi, M; Shbeh, M

2018-01-01

The present study investigated the effects of hydroxyapatite (HA) reinforced with yttria on porous scaffolds fabricated via honeycomb ceramic extrusion. Yttria was selected as it has been demonstrated to toughen other ceramics. Moreover, yttria has been surmised to suppress dehydroxylation in HA, a characteristic that prefigures decomposition thereof during sintering into mechanically weaker phases. However, the compressive strength of yttria-reinforced hydroxyapatite (Y-HA) porous scaffolds has hitherto not been reported. Y-HA was synthesised by calcining a commercially available HA with 10wt% yttria at 1000°C. Y-HA was then fabricated into porous scaffolds using an in-house honeycomb extruder, and subsequently sintered at 1200 and 1250°C. The results were compared to the uncalcined as-received commercial powder (AR-HA) and calcined pure HA powder at 1000°C (C-HA). It was discovered that calcination alone caused marked improvements to the stoichiometry, thermal stability, porosity and compressive strength of scaffolds. The improvements were ascribed to the calcined powders with less susceptibility to both agglomeration and enhanced densification. Still, differences were observed between C-HA and Y-HA at 1250°C. The compressive strength increased from 105.9 to 127.3MPa, a larger microporosity was descried and the HA matrix in Y-HA was more stoichiometric. The latter was confirmed by XRD and EDS analyses. Therefore, it was concluded that the reinforcing of hydroxyapatite with yttria improved the compressive strength and suppressed dehydroxylation of porous HA scaffolds. In addition, the compressive strength achieved demonstrated great potential for load-bearing application. Copyright © 2017 Elsevier Ltd. All rights reserved.

Solid lipid nanodispersions containing mixed lipid core and a polar heterolipid: characterization.

PubMed

Attama, A A; Schicke, B C; Paepenmüller, T; Müller-Goymann, C C

2007-08-01

This paper describes the characterization of solid lipid nanodispersions (SLN) prepared with a 1:1 mixture of theobroma oil and goat fat as the main lipid matrix and Phospholipon 90G (P90G) as a stabilizer heterolipid, using polysorbate 80 as the mobile surfactant, with a view to applying the SLN in drug delivery. The 1:1 lipid mixture and P90G constituting the lipid matrix was first homogeneously prepared by fusion. Thereafter, the SLN were formulated with a gradient of polysorbate 80 and constant lipid matrix concentration by melt-high pressure homogenisation. The SLN were characterized by time-resolved particle size analysis, zeta potential and osmotic pressure measurements, differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD). Transmission electron microscopy (TEM) and isothermal heat conduction microcalorimetry (IMC) which monitors the in situ crystallization were also carried out on the SLN containing P90G and 1.0 % w/w of polysorbate 80. The results obtained in these studies were compared with SLN prepared with theobroma oil with and without phospholipid. Particle size analysis of SLN indicated reduction in size with increase in concentration of mobile surfactant and was in the lower nanometer range after 3 months except SLN prepared without P90G or polysorbate 80. The lipid nanoparticles had negative potentials after 3 months. WAXD and DSC studies revealed low crystalline SLN after 3 months of storage except in WAXD of SLN formulated with 1.0 % w/w polysorbate 80. TEM micrograph of the SLN containing 1.0 % w/w polysorbate 80 revealed discrete particles whose sizes were in consonance with the static light scattering measurement. In situ crystallization studies in IMC revealed delayed crystallization of the SLN with 1.0 % w/w polysorbate 80. Results indicate lipid mixtures produced SLN with lower crystallinity and higher particle sizes compared with SLN prepared with theobroma oil alone with or without P90G, and would lead to higher

Reaction mechanism of electrochemical-vapor deposition of yttria-stabilized zirconia film

NASA Astrophysics Data System (ADS)

Sasaki, Hirokazu; Yakawa, Chiori; Otoshi, Shoji; Suzuki, Minoru; Ippommatsu, Masamichi

1993-10-01

The reaction mechanism for electrochemical-vapor deposition of yttria-stabilized zirconia was studied. Yttria-stabilized zirconia films were deposited on porous La(Sr)MnOx using the electrochemical-vapor-deposition process. The distribution of yttria concentration through the film was investigated by means of secondary-ion-mass spectroscopy and x-ray microanalysis and found to be nearly constant. The deposition rate was approximately proportional to the minus two-thirds power of the film thickness, the one-third power of the partial pressure of ZrCl4/YCl3 mixed gas, and the two-thirds power of the product of the reaction temperature and the electronic conductivity of yttria-stabilized zirconia film. These experimental results were explained by a model for electron transport through the YSZ film and reaction between the surface oxygen and the metal chloride on the chloride side of the film, both of which affect the deposition rate. If the film thickness is very small, the deposition rate is thought to be controlled by the surface reaction step. On the other hand, if large, the electron transport step is rate controlling.

Study of Laser Drilled Hole Quality of Yttria Stabilized Zirconia

NASA Astrophysics Data System (ADS)

Saini, Surendra K.; Dubey, Avanish K.; Pant, Piyush; Upadhyay, B. N.; Choubey, A.

2017-09-01

The Yttria Stabilized Zirconia ceramic is extensively used in aerospace, automotives, medical and microelectronics industries. These applications demand manufacturing of different macro and micro features with close tolerances in this material. To make miniature holes with accurate dimensions in advanced ceramics such as Yttria Stabilized Zirconia is very difficult due to its tailored attributes such as high toughness, hardness, strength, resistance to wear, corrosion and temperature. Due to inherent characteristics of laser drilling, researchers are working to fulfill the requirement of creation of micro holes in advanced ceramics. The present research investigates the laser drilling of 2 mm thick Yttria Stabilized Zirconia with the aim to achieve good micro holes with reduced geometrical inaccuracies and improved hole quality. The results show that multiple quality response comprising hole circularity, hole taper and recast layer thickness has been improved at optimally selected process parameters.

Zirconium nitride precipitation in nominally pure yttria-stabilized zirconia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gomez-Garcia, D.; Martinez-Fernandez, J.; Dominguez-Rodriguez, A.

Nominally pure yttria-stabilized zirconia alloys are shown to contain unexpectedly large amounts of dissolved nitrogen. Its presence in the lattice was detected through the observation of large precipitates in alloys with three different concentrations of yttria deformed in compression in argon in the temperature range 1,600--1,800 C. Electron diffraction, EDS and PEELS analyses, and Moire imaging were used to identify the precipitates as ZrN. The possible origin of the nitrogen, its likely effects on properties, and the role of annealing atmosphere are briefly discussed.

Thermal analysis of 3-mol%-yttria-stabilized tetragonal zirconia powder doped with copper oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seidensticker, J.R.; Mayo, M.J.

Thermal analysis was performed upon 3-mol%-yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) which had been doped with CuO using an aqueous adsorption technique. Cyclic differential thermal analysis (DTA) scans indicated that the CuO present on the powder surfaces first transforms to Cu{sub 2}O and then melts. The molten Cu{sub 2}O then reacts with yttria at the powder surfaces to form a new phase containing Y, Cu, and O. Because Y takes time to diffuse to the particle surfaces, the apparent melting point of this new phase appears at higher temperatures in initial DTA scans than in subsequent scans. Vaporization of the moltenmore » copper-oxide-rich phase at the temperatures studied causes a gradual shift in composition from Y{sub 2}Cu{sub 4}O{sub 5} to the less copper-rich Y{sub 2}Cu{sub 2}O{sub 5} phase. The presence of the Y{sub 2}Cu{sub 2}O{sub 5} phase in CuO-doped 3Y-TZP allows for previous sintering and superplasticity results to be explained.« less

Dispersion strengthened nickel-yttria sheet alloy produced from comminuted powders

NASA Technical Reports Server (NTRS)

Sikora, P. F.; Quatinetz, M.

1973-01-01

An investigation was conducted to determine whether a nickel matrix with yttria as a dispersoid could be produced by a comminution and blending (wet attrition-NASCAB) approach. Concentration of yttria, powder cleaning temperature, screening (sieving) of the powders, and amount of thermomechanical working were major variables. Tensile strength and stress-rupture life at 1093 C were determined. A product containing 4v/o Y2O3, cleaned at 315 or 371 C with screening exhibited 1093 C tensile strength equivalent to NASCAB Ni-4ThO2 and to commercially produced thoriated nickel sheet.

Tungsten-yttria carbide coating for conveying copper

DOEpatents

Rothman, Albert J.

1993-01-01

A method is provided for providing a carbided-tungsten-yttria coating on the interior surface of a copper vapor laser. The surface serves as a wick for the condensation of liquid copper to return the condensate to the interior of the laser for revolatilization.

Plasmachemical synthesis of nanopowders of yttria and zirconia from dispersed water-salt-organic mixtures

NASA Astrophysics Data System (ADS)

Novoselov, Ivan; Karengin, Alexander; Shamanin, Igor; Alyukov, Evgeny; Gusev, Alexander

2018-03-01

Article represents results on theoretical and experimental research of yttria and zirconia plasmachemical synthesis in air plasma from water-salt-organic mixtures "yttrium nitrate-water-acetone" and "zirconyl nitrate-water-acetone". On the basis of thermotechnical calculations the influence of organic component on lower heat value and adiabatic combustion temperature of water-salt-organic mixtures as well as compositions of mixtures providing their energy-efficient plasma treatment were determined. The calculations found the influence of mass fraction and temperature of air plasma supporting gas on the composition of plasma treatment products. It was determined the conditions providing yttria and zirconia plasmachemical synthesis in air plasma. During experiments it was b eing carried out the plasmachemical synthesis of yttria and zirconia powders in air plasma flow from water -salt-organic mixtures. Analysis of the results for obtained powders (scanning electron microscopy, X-ray diffraction analysis, BET analysis) confirm nanostructure of yttria and zirconia.

Ignitability of Diesel Fuel with an Inclusion of Ultrafine Carbon Particles

NASA Astrophysics Data System (ADS)

Krivosheev, P. N.; Leshchevich, V. V.; Shimchenko, S. Yu.; Shushkov, S. V.; Penyazkov, O. G.

2017-11-01

Nanosize carbon fuel additions were synthesized by the action of an electric discharge on a diesel fuel. Depending on the discharge regime, variously shaped carbon particles, including planar graphitized ones, were formed in the fuel. Ignitability of the produced samples was assessed by the method of initiation of a foamed fuel sample by a lowcurrent electric arc. The modified fuel showed the improvement of the ignition characteristics in the presence of a nanodispersed solid phase.

Spectroscopic investigation of the electronic structure of yttria-stabilized zirconia

NASA Astrophysics Data System (ADS)

Götsch, Thomas; Bertel, Erminald; Menzel, Alexander; Stöger-Pollach, Michael; Penner, Simon

2018-03-01

The electronic structure and optical properties of yttria-stabilized zirconia are investigated as a function of the yttria content using multiple experimental and theoretical methods, including electron energy-loss spectroscopy, Kramers-Kronig analysis to obtain the optical parameters, photoelectron spectroscopy, and density functional theory. It is shown that many properties, including the band gaps, the crystal field splitting, the so-called defect gap between acceptor (YZr') and donor (VO••) states, as well as the index of refraction in the visible range exhibit the same "zig-zag-like" trend as the unit cell height does, showing the influence of an increased yttria content as well as of the tetragonal-cubic phase transition between 8 mol % and 20 mol %Y2O3 . Also, with Čerenkov spectroscopy (CS), a new technique is presented, providing information complementary to electron energy-loss spectroscopy. In CS, the Čerenkov radiation emitted inside the TEM is used to measure the onset of optical absorption. The apparent absorption edges in the Čerenkov spectra correspond to the energetic difference between the disorder states close to the valence band and the oxygen-vacancy-related electronic states within the band gap. Theoretical computations corroborate this assignment: they find both, the acceptor states and the donor states, at the expected energies in the band structures for diverse yttria concentrations. In the end, a schematic electronic structure diagram of the area around the band gap is constructed, including the chemical potential of the electrons obtained from photoelectron spectroscopy. The latter reveal that tetragonal YSZ corresponds to a p -type semiconductor, whereas the cubic samples exhibit n -type semiconductor properties.

Electrodeposition of thin yttria-stabilized zirconia layers using glow-discharge plasma

NASA Astrophysics Data System (ADS)

Ogumi, Zempachi; Uchimoto, Yoshiharu; Tsuji, Yoichiro; Takehara, Zen-ichiro

1992-08-01

A novel process for preparation of thin yttria-stabilized zirconia (YSZ) layers was developed. This process differs from other vapor-phase deposition methods in that a dc bias circuit, separate from the plasma-generation circuit, is used for the electrodeposition process. The YSZ layer was electrodeposited from ZrCl4 and YCl3 on a nonporous calcia-stabilized zirconia substrate. Scanning electron microscopy, electron probe microanalysis, electron spectroscopy for chemical analysis, and x-ray-diffraction measurements confirmed the electrodeposition of a smooth, pinhole-free yttria-stabilized zirconia film of about 3 μm thickness.

Single-Crystal Elastic Constants of Yttria (Y2O3) Measured to High Temperatures

NASA Technical Reports Server (NTRS)

Sayir, Ali; Palko, James W.; Kriven, Waltraud M.; Sinogeikin, Sergey V.; Bass, Jay D.

2001-01-01

Yttria, or yttrium sesquioxide (Y2O3), has been considered for use in nuclear applications and has gained interest relatively recently for use in infrared optics. Single crystals of yttria have been grown successfully at the NASA Glenn Research Center using a laser-heated float zone technique in a fiber and rod. Such samples allow measurement of the single-crystal elastic properties, and these measurements provide useful property data for the design of components using single crystals. They also yield information as to what degree the elastic properties of yttria ceramics are a result of the intrinsic properties of the yttria crystal in comparison to characteristics that may depend on processing, such as microstructure and intergranular phases, which are common in sintered yttria. The single-crystal elastic moduli are valuable for designing such optical components. In particular, the temperature derivatives of elastic moduli allow the dimensional changes due to heating under physical constraints, as well as acoustic excitation, to be determined. The single-crystal elastic moduli of yttria were measured by Brillouin spectroscopy up to 1200 C. The room-temperature values obtained were C(sub 11) = 223.6 + 0.6 GPa, C(sub 44) = 74.6 + 0.5 GPa, and C(sub 12) = 112.4 + 1.0 GPa. The resulting bulk and (Voigt-Reuss-Hill) shear moduli were K = 149.5 + 1.0 GPa and G(sub VRH) = 66.3 + 0.8 GPa, respectively. Linear least-squares regressions to the variation of bulk and shear moduli with temperature resulted in derivatives of dK/dT = -17 + 2 MPa/C and dG(sub VRH)/dT = -8 + 2 MPa/ C. Elastic anisotropy was found to remain essentially constant over the temperature range studied.

Enhancing hydrogen storage performances of MgH2 by Ni nano-particles over mesoporous carbon CMK-3.

PubMed

Chen, Gang; Zhang, Yao; Chen, Jian; Guo, Xinli; Zhu, Yunfeng; Li, Liquan

2018-06-29

Nano-dispersed Ni particles over mesoporous carbon material CMK-3 (Ni/CMK-3) was fabricated by means of impregnation-reduction strategy using precursor NiCl 2  · 6H 2 O, which is beneficial to improving the de/rehydrogenation performances of MgH 2 . The dehydrogenation onset temperature of MgH 2 -Ni/CMK-3 is significantly lowered by 170 K from that of pristine MgH 2 (around 603 K). Totally 5.9 wt% of hydrogen absorption capacity is liberated within 1 h at a temperature of 423 K under a pressure of 3 MPa. This composite can absorb 3.9 wt% hydrogen even at a temperature of 328 K under 3 MPa H 2 . Activation energy values of both dehydrogenation (43.4 kJ mol -1 ) and rehydrogenation (37.4 kJ mol -1 ) for MgH 2 -Ni/CMK-3 are greatly enhanced from those of as-milled MgH 2 . Ni/CMK-3 also slightly destabilizes the dehydrogenation of MgH 2 by 1.5 kJ mol [Formula: see text] The enhanced performances can be attributed to the synergistic effects of both destabilization and activation from nano-dispersed Ni particles.

Enhancing hydrogen storage performances of MgH2 by Ni nano-particles over mesoporous carbon CMK-3

NASA Astrophysics Data System (ADS)

Chen, Gang; Zhang, Yao; Chen, Jian; Guo, Xinli; Zhu, Yunfeng; Li, Liquan

2018-06-01

Nano-dispersed Ni particles over mesoporous carbon material CMK-3 (Ni/CMK-3) was fabricated by means of impregnation-reduction strategy using precursor NiCl2 · 6H2O, which is beneficial to improving the de/rehydrogenation performances of MgH2. The dehydrogenation onset temperature of MgH2–Ni/CMK-3 is significantly lowered by 170 K from that of pristine MgH2 (around 603 K). Totally 5.9 wt% of hydrogen absorption capacity is liberated within 1 h at a temperature of 423 K under a pressure of 3 MPa. This composite can absorb 3.9 wt% hydrogen even at a temperature of 328 K under 3 MPa H2. Activation energy values of both dehydrogenation (43.4 kJ mol‑1) and rehydrogenation (37.4 kJ mol‑1) for MgH2–Ni/CMK-3 are greatly enhanced from those of as-milled MgH2. Ni/CMK-3 also slightly destabilizes the dehydrogenation of MgH2 by 1.5 kJ mol {{{{H}}}2}-1. The enhanced performances can be attributed to the synergistic effects of both destabilization and activation from nano-dispersed Ni particles.

Formation and enhanced biocidal activity of water-dispersable organic nanoparticles

NASA Astrophysics Data System (ADS)

Zhang, Haifei; Wang, Dong; Butler, Rachel; Campbell, Neil L.; Long, James; Tan, Bien; Duncalf, David J.; Foster, Alison J.; Hopkinson, Andrew; Taylor, David; Angus, Doris; Cooper, Andrew I.; Rannard, Steven P.

2008-08-01

Water-insoluble organic compounds are often used in aqueous environments in various pharmaceutical and consumer products. To overcome insolubility, the particles are dispersed in a medium during product formation, but large particles that are formed may affect product performance and safety. Many techniques have been used to produce nanodispersions-dispersions with nanometre-scale dimensions-that have properties similar to solutions. However, making nanodispersions requires complex processing, and it is difficult to achieve stability over long periods. Here we report a generic method for producing organic nanoparticles with a combination of modified emulsion-templating and freeze-drying. The dry powder composites formed using this method are highly porous, stable and form nanodispersions upon simple addition of water. Aqueous nanodispersions of Triclosan (a commercial antimicrobial agent) produced with this approach show greater activity than organic/aqueous solutions of Triclosan.

High-temperature erosion of plasma-sprayed, yttria-stabilized zirconia in a simulated turbine environment

NASA Technical Reports Server (NTRS)

Hanschuh, R. F.

1984-01-01

A series of rig calibration and high temperature tests simulating gas path seal erosion in turbine engines were performed at three impingement angles and at three downstream locations. Plasma sprayed, yttria stablized zirconia specimens were tested. Steady state erosion curves presented for 19 test specimens indicate a brittle type of material erosion despite scanning electron microscopy evidence of plastic deformation. Steady state erosion results were not sensitive to downstream location but were sensitive to impingement angle. At difference downstream locations specimen surface temperature varied from 1250 to 1600 C (2280 to 2900 F) and particle velocity varied from 260 to 320 m/s (850 to 1050 ft/s). The mass ratio of combustion products to erosive grit material was typically 240.

Yttria catalyzed microstructural modifications in oxide dispersion strengthened V-4Cr-4Ti alloys synthesized by field assisted sintering technique

NASA Astrophysics Data System (ADS)

Krishnan, Vinoadh Kumar; Sinnaeruvadi, Kumaran; Verma, Shailendra Kumar; Dash, Biswaranjan; Agrawal, Priyanka; Subramanian, Karthikeyan

2017-08-01

The present work deals with synthesis, characterisation and elevated temperature mechanical property evaluation of V-4Cr-4Ti and oxide (yttria = 0.3, 0.6 and 0.9 at%) dispersion strengthened V-4Cr-4Ti alloy processed by mechanical alloying and field-assisted sintering, under optimal conditions. Microstructural parameters of both powder and sintered samples were deduced by X-ray diffraction (XRD) and further confirmed with high resolution transmission electron microscopy. Powder diffraction and electron microscopy study show that ball milling of starting elemental powders (V-4Cr-4Ti) with and without yttria addition has resulted in single phase α-V (V-4Cr-4Ti) alloy. Wherein, XRD and electron microscopy images of sintered samples have revealed phase separation (viz., Cr-V and Ti-V) and domain size reduction, with yttria addition. The reasons behind phase separation and domain size reduction with yttria addition during sintering are extensively discussed. Microhardness and high temperature compression tests were done on sintered samples. Yttria addition (0.3 and 0.6 at.%) increases the elevated temperature compressive strength and strain hardening exponent of α-V alloys. High temperature compression test of 0.9 at% yttria dispersed α-V alloy reveals a glassy behaviour.

Wear behavior of carbide tool coated with Yttria-stabilized zirconia nano particles.

NASA Astrophysics Data System (ADS)

Jadhav, Pavandatta M.; Reddy, Narala Suresh Kumar

2018-04-01

Wear mechanism takes predominant role in reducing the tool life during machining of Titanium alloy. Challenges of wear mechanisms such as variation in chip, high pressure loads and spring back are responsible for tool wear. In addition, many tool materials are inapt for machining due to low thermal conductivity and volume specific heat of these materials results in high cutting temperature during machining. To confront this issue Electrostatic Spray Coating (ESC) coating technique is utilized to enhance the tool life to an acceptable level. The Yttria Stabilized Zirconia (YSZ) acts as a thermal barrier coating having high thermal expansion coefficient and thermal shock resistance. This investigation focuses on the influence of YSZ nanocoating on the tungsten carbide tool material and improve the machinability of Ti-6Al-4V alloy. YSZ nano powder was coated on the tungsten carbide pin by using ESC technique. The coatings have been tested for wear and friction behavior by using a pin-on-disc tribological tester. The dry sliding wear test was performed on Titanium alloy (Ti-6Al-4V) disc and YSZ coated tungsten carbide (pin) at ambient atmosphere. The performance parameters like wear rate and temperature rise were considered upon performing the dry sliding test on Ti-6Al-4V alloy disc. The performance parameters were calculated by using coefficient of friction and frictional force values which were obtained from the pin on disc test. Substantial resistance to wear was achieved by the coating.

Thickness effects of yttria-doped ceria interlayers on solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Fan, Zeng; An, Jihwan; Iancu, Andrei; Prinz, Fritz B.

2012-11-01

Determining the optimal thickness range of the interlayed yttria-doped ceria (YDC) films promises to further enhance the performance of solid oxide fuel cells (SOFCs) at low operating temperatures. The YDC interlayers are fabricated by the atomic layer deposition (ALD) method with one super cycle of the YDC deposition consisting of 6 ceria deposition cycles and one yttria deposition cycle. YDC films of various numbers of ALD super cycles, ranging from 2 to 35, are interlayered into bulk fuel cells with a 200 um thick yttria-stabilized zirconia (YSZ) electrolyte. Measurements and analysis of the linear sweep voltammetry of these fuel cells reveal that the performance of the given cells is maximized at 10 super cycles. Auger elemental mapping and X-ray photoelectron spectroscopy (XPS) techniques are employed to determine the film completeness, and they verify 10 super cycles of YDC to be the critical thickness point. This optimal YDC interlayer condition (6Ce1Y × 10 super cycles) is applied to the case of micro fuel cells as well, and the average performance enhancement factor is 1.4 at operating temperatures of 400 and 450 °C. A power density of 1.04 W cm-2 at 500 °C is also achieved with the optimal YDC recipe.

Precise calculations in simulations of the interaction of low energy neutrons with nano-dispersed media

NASA Astrophysics Data System (ADS)

Artem'ev, V. A.; Nezvanov, A. Yu.; Nesvizhevsky, V. V.

2016-01-01

We discuss properties of the interaction of slow neutrons with nano-dispersed media and their application for neutron reflectors. In order to increase the accuracy of model simulation of the interaction of neutrons with nanopowders, we perform precise quantum mechanical calculation of potential scattering of neutrons on single nanoparticles using the method of phase functions. We compare results of precise calculations with those performed within first Born approximation for nanodiamonds with the radius of 2-5 nm and for neutron energies 3 × 10-7-10-3 eV. Born approximation overestimates the probability of scattering to large angles, while the accuracy of evaluation of integral characteristics (cross sections, albedo) is acceptable. Using Monte-Carlo method, we calculate albedo of neutrons from different layers of piled up diamond nanopowder.

Defects Induced Enhancement of Eu3+ Emission in Yttria ( Y2O3:Eu3+)

NASA Astrophysics Data System (ADS)

Jagannathan, R.; Kutty, T.; Kottaisamy, M.; Jeyagopal, P.

1994-11-01

Bixbyite type Y2O3:Eu3+ apart from being the efficient red phosphor extensively used in trichromatic fluorescent lamps, it is a typical system one can apply Jørgensen's refined electron spin pairing theory. This can be used to explain the enhancement in Eu3+ emission intensity observed with the aliovalent substitution in the yttria host matrix. Results based on these are explained qualitatively by considering a simple configurational coordinate model. Futhermore, an insight into the different types of defects induced with the aliovalent substitution in the yttria lattice has become possible with EPR probe.

Atomistic modeling of La 3+ doping segregation effect on nanocrystalline yttria-stabilized zirconia

DOE PAGES

Zhang, Shenli; Sha, Haoyan; Castro, Ricardo H. R.; ...

2018-01-01

The effect of La 3+ doping on the structure and ionic conductivity change in nanocrystalline yttria-stabilized zirconia (YSZ) was studied using a combination of Monte Carlo and molecular dynamics simulations.

Design and Fabrication of Porous Yttria-Stabilized Zirconia Ceramics for Hot Gas Filtration Applications

NASA Astrophysics Data System (ADS)

Shahini, Shayan

Hot gas filtration has received growing attention in a variety of applications over the past few years. Yttria-stabilized zirconia (YSZ) is a promising candidate for such an application. In this study, we fabricated disk-type porous YSZ filters using the pore forming procedure, in which poly methyl methacrylate (PMMA) was used as the pore-forming agent. After fabricating the pellets, we characterized them to determine their potential for application as gas filters. We investigated the effect of sintering temperature, polymer particle size, and polymer-to-ceramic ratio on the porosity, pore size, gas permeability, and Vickers hardness of the sintered pellets. Furthermore, we designed two sets of experiments to investigate the robustness of the fabricated pellets--i.e., cyclic heating/cooling and high temperature exposure. This study ushers in a robust technique to fabricate such porous ceramics, which have the potential to be utilized in hot gas filtration.

In situ probing of temperature in radio frequency thermal plasma using Yttrium ion emission lines during synthesis of yttria nanoparticles

NASA Astrophysics Data System (ADS)

Dhamale, G. D.; Tiwari, N.; Mathe, V. L.; Bhoraskar, S. V.; Ghorui, S.

2017-07-01

Particle feeding is used in the most important applications of radio frequency (r.f.) thermal plasmas like synthesis of nanoparticles and particle spheroidization. The study reports an in-situ investigation of radial distribution of temperature in such devices using yttrium ion emission lines under different rates of particle loading during synthesis of yttria nanoparticles. A number of interesting facts about the response of r.f. plasma to the rate of particle loading, hitherto unknown, are revealed. Observed phenomena are supported with experimental data from fast photographic experiments and actual synthesis results. The use of the Abel inversion technique together with simultaneous multi-track acquisition of emission spectra from different spatial locations using a CCD based spectrometer allowed us to extract accurate distribution of temperature inside the plasma in the presence of inherent instabilities. The temperature profiles of this type of plasma have been measured possibly for the first time while particles are being fed into the plasma. Observed changes in the temperature profiles as the particle feed rate increases are very significant. Reaction forces resulting from particle evaporation, and increased skin depth owing to the decrease in electrical conductivity in the edge region are proposed as the two different mechanisms to account for the observed changes in the temperature profile as the powder feed rate is increased. Quantitative analyses supporting the proposed mechanisms are presented.

Study on the influences of reduction temperature on nickel-yttria-stabilized zirconia solid oxide fuel cell anode using nickel oxide-film electrode

NASA Astrophysics Data System (ADS)

Jiao, Zhenjun; Ueno, Ai; Suzuki, Yuji; Shikazono, Naoki

2016-10-01

In this study, the reduction processes of nickel oxide at different temperatures were investigated using nickel-film anode to study the influences of reduction temperature on the initial performances and stability of nickel-yttria-stabilized zirconia anode. Compared to conventional nickel-yttria-stabilized zirconia composite cermet anode, nickel-film anode has the advantage of direct observation at nickel-yttria-stabilized zirconia interface. The microstructural changes were characterized by scanning electron microscopy. The reduction process of nickel oxide is considered to be determined by the competition between the mechanisms of volume reduction in nickel oxide-nickel reaction and nickel sintering. Electrochemical impedance spectroscopy was applied to analyze the time variation of the nickel-film anode electrochemical characteristics. The anode performances and microstructural changes before and after 100 hours discharging and open circuit operations were analyzed. The degradation of nickel-film anode is considered to be determined by the co-effect between the nickel sintering and the change of nickel-yttria-stabilized zirconia interface bonding condition.

Kinetic Monte Carlo Investigation of the Effects of Vacancy Pairing on Oxygen Diffusivity in Yttria-Stabilized Zirconia

NASA Technical Reports Server (NTRS)

Good, Brian S.

2011-01-01

Yttria-stabilized zirconia s high oxygen diffusivity and corresponding high ionic conductivity, and its structural stability over a broad range of temperatures, have made the material of interest for use in a number of applications, for example, as solid electrolytes in fuel cells. At low concentrations, the stabilizing yttria also serves to increase the oxygen diffusivity through the presence of corresponding oxygen vacancies, needed to maintain charge neutrality. At higher yttria concentration, however, diffusivity is impeded by the larger number of relatively high energy migration barriers associated with yttrium cations. In addition, there is evidence that oxygen vacancies preferentially occupy nearest-neighbor sites around either dopant or Zr cations, further affecting vacancy diffusion. We present the results of ab initio calculations that indicate that it is energetically favorable for oxygen vacancies to occupy nearest-neighbor sites adjacent to Y ions, and that the presence of vacancies near either species of cation lowers the migration barriers. Kinetic Monte Carlo results from simulations incorporating this effect are presented and compared with results from simulations in which the effect is not present.

Studies on copper-yttria nanocomposites: high-energy ball milling versus chemical reduction method.

PubMed

Joshi, P B; Rehani, Bharati; Naik, Palak; Patel, Swati; Khanna, P K

2012-03-01

Oxide dispersion-strengthened copper-base composites are widely used for applications demanding high tensile strength, high hardness along with good electrical and thermal conductivity. Oxides of metals like aluminium, cerium, yttrium and zirconium are often used for this purpose as fine and uniformly distributed dispersoid particles in soft and ductile copper matrix. Such composites find applications as electrical contacts, resistance-welding tips, lead wires, continuous casting moulds, etc. In this investigation an attempt has been made to produce copper-yttria nanocomposites using two different morphologies of copper powder and two different processing routes namely, high-energy milling and in-situ chemical reduction. The synthesized powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) for their phase identification and morphological study. The nanocomposite powders in each case were subsequently processed to obtain bulk solids by classical powder metallurgy route of press-sinter-repress. The resultant bulk solid compacts were subjected to property evaluation. The study revealed that the properties of Cu-Y2O3 nanocomposites depend on the processing route used and in turn on the resultant powder morphology.

Novel erbia-yttria co-doped zirconia fluorescent thermal history sensor

NASA Astrophysics Data System (ADS)

Copin, E. B.; Massol, X.; Amiel, S.; Sentenac, T.; Le Maoult, Y.; Lours, P.

2017-01-01

Thermochromic pigments are commonly used for off-line temperature mapping on components from systems operating at a temperature higher than 1073 K. However, their temperature resolution is often limited by the discrete number of color transitions they offer. This paper investigates the potential of erbia-yttria co-doped zirconia as a florescent thermal history sensor alternative to thermochromic pigments. Samples of yttria-stabilized zirconia powder (YSZ, 8.3 mol% YO1.5) doped with 1.5 mol% ErO1.5 and synthesized by a sol-gel route are calcined for 15 minutes under isothermal conditions between 1173 and 1423 K. The effects of temperature on their crystal structure and room temperature fluorescence properties are then studied. Results show a steady increase of the crystallinity of the powders with temperature, causing a significant and permanent increase of the emission intensity and fluorescence lifetime which could be used to determine temperature with a calculated theoretical resolution lower than 1 K for intensity. The intensity ratio obtained using a temperature insensitive YSZ:Eu3+ reference phosphor is proposed as a more robust parameter regarding experimental conditions for determining thermal history. Finally, the possibilities for integrating this fluorescent marker into sol-gel deposited coatings for future practical thermal history sensing applications is also discussed.

Novel nanodisperse composite cathode for rechargeable lithium/polymer batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Striebel, K.A.; Wen, S.J.; Ghantous, D.I.

1997-05-01

A novel approach to the design of a composite positive electrode for lithium/polymer cells based on a polyethylene oxide (PEO) polymer, manganese (II), and lithium hydroxide has been discovered. A chemical reaction leading to a stable suspension occurs when the precursor salts are added directly to a polymer solution. The electrode film is cast directly and then vacuum-dried with no calcination step. The film is amorphous as-prepared and has been named the nanodisperse composite cathode, or NCC. Film characterization with x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy indicates that the Mn (II) has been oxidized to Mn (IV), whichmore » forms a complex with the PEO. This leads to highly disperse Mn sites within the polymer matrix and highly mobile Li ions within the PEO. Cells have been assembled with NCC films, PEO-LiN(SO{sub 2}CF{sub 3}){sub 2} electrolyte and lithium metal, and cycled at 85 to 105 C at current densities of 0.2 mA/cm{sup 2} between the voltage limits of 3.5 and 2.0 V. Discharge capacities as high as 340 mAh/g-cathode film have been achieved on the first half-cycle. The discharge capacity declines consistently during a formation process to steady values as high as 50 mAh/g-cathode. This cathode capacity is equivalent to an active material capacity of 150 mAh/g in a composite cathode at a loading of 30 weight percent. The synthesis process for the NCC is simple, should be relatively easy to scale up, and should lead to an extremely useful composite cathode for a lithium polymer battery.« less

Stability of yttria-stabilized zirconia during pyroprocessing tests

NASA Astrophysics Data System (ADS)

Choi, Eun-Young; Lee, Jeong; Lee, Sung-Jai; Kim, Sung-Wook; Jeon, Sang-Chae; Cho, Soo Haeng; Oh, Seung Chul; Jeon, Min Ku; Lee, Sang Kwon; Kang, Hyun Woo; Hur, Jin-Mok

2016-07-01

In this study, the feasibility of yttria-stabilized zirconia (YSZ) was investigated for use as a ceramic material, which can be commonly used for both electrolytic reduction and electrorefining. First, the stability of YSZ in salts for electrolytic reduction and electrorefining was examined. Then, its stability was demonstrated by a series of pyroprocessing tests, such as electrolytic reduction, LiCl distillation, electrorefining, and LiClsbnd KCl distillation, using a single stainless steel wire mesh basket containing fuel and YSZ. A single basket was used by its transportation from one test to subsequent tests without the requirements for unloading.

Phase analysis of plasma-sprayed zirconia-yttria coatings

NASA Technical Reports Server (NTRS)

Shankar, N. R.; Berndt, C. C.; Herman, H.

1983-01-01

Phase analysis of plasma-sprayed 8 wt pct-yttria-stabilized zirconia (YSZ) thermal barrier coatings and powders was carried out by X-ray diffraction. Step scanning was used for increased peak resolution. Plasma spraying of the YSZ powder into water or onto a steel substrate to form a coating reduced the cubic and monoclinic phases with a simultaneous increase in the tetragonal phase. Heat treatment of the coating at 1150 C for 10 h in an Ar atmosphere increased the amount of cubic and monoclinic phases. The implications of these transformations on coating performance and integrity are discussed.

Development of a High Temperature Heater using an Yttria Stabilized Zirconia Cored Brick Matrix

NASA Technical Reports Server (NTRS)

Smith, K. W.; Decoursin, D. G.

1971-01-01

The Ames pilot heater is a ceramic regenerative heater that provides high temperature air for aerodynamic and combustion experiments. The development of this heater to provide a heat storage bed with temperature capability of about 4600 R is described. A bed was designed and installed having cored brick elements of yttria-stabilized zirconia. The bed dimensions were 14 inches in diameter by 10 feet high. The thermal stress limitations of the bed were studied and maximum air flow rates based upon these limits were established. A combustion reheat system was designed and installed to provide the necessary control over the bed temperature distribution. The revised heater system was successfully operated at a maximum bed temperature of 4600 R. The successful operation demonstrated that yttria-stabilized zirconia cored brick can satisfy the high temperature-long duration requirement for storage heater applications.

Multiobjective Optimization of Atmospheric Plasma Spray Process Parameters to Deposit Yttria-Stabilized Zirconia Coatings Using Response Surface Methodology

NASA Astrophysics Data System (ADS)

Ramachandran, C. S.; Balasubramanian, V.; Ananthapadmanabhan, P. V.

2011-03-01

Atmospheric plasma spraying is used extensively to make Thermal Barrier Coatings of 7-8% yttria-stabilized zirconia powders. The main problem faced in the manufacture of yttria-stabilized zirconia coatings by the atmospheric plasma spraying process is the selection of the optimum combination of input variables for achieving the required qualities of coating. This problem can be solved by the development of empirical relationships between the process parameters (input power, primary gas flow rate, stand-off distance, powder feed rate, and carrier gas flow rate) and the coating quality characteristics (deposition efficiency, tensile bond strength, lap shear bond strength, porosity, and hardness) through effective and strategic planning and the execution of experiments by response surface methodology. This article highlights the use of response surface methodology by designing a five-factor five-level central composite rotatable design matrix with full replication for planning, conduction, execution, and development of empirical relationships. Further, response surface methodology was used for the selection of optimum process parameters to achieve desired quality of yttria-stabilized zirconia coating deposits.

Single Crystal Fibers of Yttria-Stabilized Cubic Zirconia with Ternary Oxide Additions

NASA Technical Reports Server (NTRS)

Ritzert, F. J.; Yun, H. M.; Miner, R. V.

1997-01-01

Single crystal fibers of yttria (Y2O3)-stabilized cubic zirconia, (ZrO2) with ternary oxide additions were grown using the laser float zone fiber processing technique. Ternary additions to the ZrO2-Y2O3 binary system were studied aimed at increasing strength while maintaining the high coefficient of thermal expansion of the binary system. Statistical methods aided in identifying the most promising ternary oxide candidate (Ta2O5, Sc2O3, and HfO2) and optimum composition. The yttria, range investigated was 14 to 24 mol % and the ternary oxide component ranged from 1 to 5 mol %. Hafnium oxide was the most promising ternary oxide component based on 816 C tensile strength results and ease of fabrication. The optimum composition for development was 81 ZrO2-14 Y203-5 HfO2 based upon the same elevated temperature strength tests. Preliminary results indicate process improvements could improve the fiber performance. We also investigated the effect of crystal orientation on strength.

On the bulk degradation of yttria-stabilized nanocrystalline zirconia dental implant abutments: an electron backscatter diffraction study.

PubMed

Ocelík, V; Schepke, U; Rasoul, H Haji; Cune, M S; De Hosson, J Th M

2017-08-01

Degradation of yttria-stabilized zirconia dental implants abutments due to the tetragonal to monoclinic phase transformation was studied in detail by microstructural characterization using Electron Back Scatter Diffraction (EBSD). The amount and distribution of the monoclinic phase, the grain-size distribution and crystallographic orientations between tetragonal and monoclinic crystals in 3 mol.% yttria-stabilized polycrystalline zirconia (3Y-TZP) were determined in two different types of nano-crystalline dental abutments, even for grains smaller than 400 nm. An important and novel conclusion is that no substantial bulk degradation of 3Y-TZP dental implant abutments was detected after 1 year of clinical use.

High-power hybrid plasma spraying of large yttria-stabilized zirconia powder

NASA Astrophysics Data System (ADS)

Huang, Heji; Eguchi, Keisuke; Yoshida, Toyonobu

2006-03-01

To testify to the advantage of large ceramic powder spraying, numerical simulations and experimental studies on the behavior of large yttria-stabilized zirconia (YSZ) powder in a high-power hybrid plasma spraying process have been carried out. Numeric predictions and experimental results showed that, with the high radio frequency (RF) input power of 100 kW, the most refractory YSZ powder with particle sizes as large as 88 μm could be fully melted and well-flattened splats could be formed. A large degree of flattening (ξ) of 4.7 has been achieved. The improved adhesive strength between the large splat and the substrate was confirmed based on the measurement of the crack density inside of the splats. A thick YSZ coating >300 μm was successfully deposited on a large CoNiCrAlY-coated Inconel substrate (50×50×4 mm in size). The ultradense microstructure without clear boundaries between the splats and the clean and crack-free interface between the top-coat and the bond-coat also indicate the good adhesion. These results showed that highpower hybrid plasma spraying of large ceramic powder is a very promising process for deposition of highquality coatings, especially in the application of thermal barrier coatings (TBCs).

Effects of compositional changes on the performance of a thermal barrier coating system. [yttria-stabilized zirconia coatings on gas turbine engine blades

NASA Technical Reports Server (NTRS)

Stecura, S.

1978-01-01

Currently proposed thermal barrier systems for aircraft gas turbine engines consist of NiCrAlY bond coating covered with an insulating oxide layer of yttria-stabilized zirconia. The effect of yttrium concentration (from 0.15 to 1.08 w/o) in the bond coating and the yttria concentration (4 to 24.4 w/o) in the oxide layer were evaluated. Furnace, natural gas-oxygen torch, and Mach 1.0 burner rig cyclic tests on solid specimens and air-cooled blades were used to identify trends in coating behavior. Results indicate that the combinations of yttrium levels between 0.15 - 0.35 w/o in the bond coating and the yttria concentration between 6 - 8 w/o in the zirconium oxide layer were the most adherent and resistant to high temperature cyclic exposure.

Energy-filtered TEM imaging and EELS study of ODS particles and argon-filled cavities in ferritic-martensitic steels.

PubMed

Klimiankou, M; Lindau, R; Möslang, A

2005-01-01

Oxide-dispersion-strengthened (ODS) ferritic-martensitic steels with yttrium oxide (Y(2)O(3)) have been produced by mechanical alloying and hot isostatic pressing for use as advanced material in fusion power reactors. Argon gas, usually widely used as inert gas during mechanical alloying, was surprisingly detected in the nanodispersion-strengthened materials. Energy-filtered transmission electron microscopy (EFTEM) and electron energy loss spectroscopy (EELS) led to the following results: (i) chemical composition of ODS particles, (ii) voids with typical diameters of 1-6 nm are formed in the matrix, (iii) these voids are filled with Ar gas, and (iv) the high-density nanosized ODS particles serve as trapping centers for the Ar bubbles. The Ar L(3,2) energy loss edge at 245 eV as well as the absorption features of the ODS particle elements were identified in the EELS spectrum. The energy resolution in the EEL spectrum of about 1.0 eV allows to identify the electronic structure of the ODS particles.

Effect of Porosity on Synthetic Sand Infiltration within Yttria-Stabilized Zirconia Pellets

DTIC Science & Technology

Sand infiltration was investigated for several yttria-stabilized zirconia (YSZ) pellets of varying porosity. The pellets were synthesized through...each. Several characterization techniques were used to correlate the sand infiltration to porosity. It was found that there was no significant...difference in the results of low and high porosity samples. Interestingly, sand had infiltrated all samples to some degree although the magnitude of the

[Interface compatibility between tooth-like yttria-stabilized tetragonal zirconia polycrystal by adding rare-earth oxide and Vita VM9 veneering porcelain].

PubMed

Gao, Yan; Zhang, Fu-qiang; He, Fan

2011-10-01

To evaluate the interface compatibility between tooth-like yttria-stabilized tetragonal zirconia polycrystal(Y-TZP) by adding rare-earth oxide and Vita VM9 veneering porcelain. Six kinds(S1,S2,S3,S4,S5,S6) of tooth-like yttria stabilized tetragonal zirconia polycrystal were made by introducing internal colorating technology to detect the thermal shock resistance and interface bonding strength with Vita VM9 Bsaedentin. Statistical analysis was performed using SAS6.12 software package. There was no gap between the layers via hot shocking test.The shear bonding strength between Y-TZP and VitaVM9 was higher and the value was (36.03±3.82) to (37.98±4.89) MPa. By adding rare-earth oxide to yttria-stabilized tetragonal zirconia polycrystal ,better compatibility between the layer (TZP and Vita VM9) can be formed which is of better interface integrate and available for clinical applications.

High-Temperature Particulate Matter Filtration with Resilient Yttria-Stabilized ZrO2 Nanofiber Sponge.

PubMed

Wang, Haolun; Lin, Sen; Yang, Shen; Yang, Xudong; Song, Jianan; Wang, Dong; Wang, Haiyang; Liu, Zhenglian; Li, Bo; Fang, Minghao; Wang, Ning; Wu, Hui

2018-05-01

Particulate matter (PM) is a major air pollutant in many regions, jeopardizing ecosystems and public health. Filtration at pollutant source is one of the most important ways to protect the environment, however, considering the high-temperature exhaust gas emissions, effective removal of PM and related pollutants from their sources remains a major challenge. In this study, a resilient, heat-resisting, and high-efficiency PM filter based on yttria-stabilized ZrO 2 (YSZ) nanofiber sponge produced with a scalable solution blow spinning process is reported. The porous 3D sponge composed of YSZ nanofibers is lightweight (density of 20 mg cm -3 ) and resilient at both room temperature and high temperatures. At room-temperature conditions, the YSZ nanofiber sponge exhibits 99.4% filtration efficiency for aerosol particles with size in the range of 20-600 nm, associated with a low pressure drop of only 57 Pa under an airflow velocity of 4.8 cm s -1 . At a high temperature of 750 °C, the ceramic sponge maintains a high filtration efficiency of 99.97% for PM 0.3-2.5 under a high airflow velocity of 10 cm s -1 . A practical vehicle exhaust filter to capture particles with filtration efficiency of >98.3% is also assembled. Hence, the YSZ nanofiber sponge has enormous potential to be applied in industry. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural evolution of plasma-sprayed nanoscale 3 mol% and 5 mol% yttria-stabilized zirconia coatings during sintering

NASA Astrophysics Data System (ADS)

Zhao, Yan; Gao, Yang

2017-12-01

The microstructure of plasma-sprayed nanostructured yttria-stabilized zirconia (YSZ) coatings may change during high-temperature exposure, which would influence the coating performance and service lifetime. In this study, the phase structure and the microstructural evolution of 3YSZ (zirconia-3 mol% yttria) and 5YSZ (zirconia-5 mol% yttria) nanostructured coatings were investigated by means of sintering at 1400 °C for 50-100 h. The microhardness, elastic moduli, and thermal shock cycles of the 3YSZ and 5YSZ nanostructured coatings were also investigated. The results showed that the redistribution of yttrium ions at 1400 °C caused the continuous increase of monoclinic-phase zirconia, but no obvious inter-splat cracking formed at the cross-sections, even after 100 h. Large voids appeared around the nanoporous zone because of the sintering of nanoscale granules upon high-temperature exposure. The microhardness and elastic moduli of the nanostructured coatings first increased and then decreased with increasing sintering times. The growth rate of the nanograins in the 3YSZ coating was lower than that in 5YSZ, which slowed the changes in 3YSZ coating porosity during sintering. Although the 3YSZ coating was prone to monoclinic phase transition, the experimental results showed that the thermal shock resistance of the 3YSZ coating was better than that of the 5YSZ coating.

Evaluation of self-adhesive resin cement bond strength to yttria-stabilized zirconia ceramic (Y-TZP) using four surface treatments.

PubMed

Miragaya, Luciana; Maia, Luciane Cople; Sabrosa, Carlos Eduardo; de Goes, Mário Fernando; da Silva, Eduardo Moreira

2011-10-01

To evaluate the influence of four surface treatments on the bond strength of a self-adhesive resin cement to an yttria-stabilized zirconia (Y-TZP) ceramic material (Lava Frame zirconia). Forty plates (8 x 6 x 1 mm) of a Y-TZP ceramic restorative material were randomly assigned to four groups (n = 10) according to the surface treatments: control, no treatment; airborne-particle abrasion with 50-μm Al2O3; coating with an MDP-based primer; conditioning with Rocatec System. The ceramic plates treated with each of the four methods were further divided into 2 subgroups according to the resin cement tested: RelyXTM ARC (ARC, conventional) and RelyXTM Unicem (Ucem, self-adhesive). The resin cements were put into PVC tubes (diameter 0.75 mm, 0.5 mm height) placed on the ceramic plate surfaces. After water storage at 37°C for 24 h, the specimens were submitted to a microshear bond strength (μSBS) test at a crosshead speed of 1.0 mm/min. The surface treatments significantly influenced the μSBS (p < 0.05). For the four surface treatments, UCem presented significantly higher μSBS than ARC (p < 0.05). For both resin cements, the best result was produced by the MDP-based primer: ARC 15.9 ± 5.0 MPa and UCem 36.2 ± 2.1 MPa. The highest μSBS values were presented by UCem on ceramic plates treated with the MDP-based primer (36.2 ± 2.1 MPa) and Rocatec system (37.4 ± 2.3 MPa). Irrespective of the surface treatment, the self-adhesive resin cement performed better in terms of bond strength to yttria-stabilized zirconia ceramic than did conventional resin cement.

Towards an aerogel-based coating for aerospace applications: reconstituting aerogel particles via spray drying

NASA Astrophysics Data System (ADS)

Bheekhun, N.; Abu Talib, A. R.; Mustapha, S.; Ibrahim, R.; Hassan, M. R.

2016-10-01

Silica aerogel is an ultralight and highly porous nano-structured ceramic with its thermal conductivity being the lowest than any solids. Although aerogels possess fascinating physical properties, innovative solutions to tackle today's problems were limited due to their relative high manufacturing cost in comparison to conventional materials. Recently, some producers have brought forward quality aerogels at competitive costs, and thereby opening a panoply of applied research in this field. In this paper, the feasibility of spray-drying silica aerogel to tailor its granulometric property is studied for thermal spraying, a novel application of aerogels that is never tried before in the academic arena. Aerogel-based slurries with yttria stabilised zirconia as a secondary ceramic were prepared and spray-dried according to modified T aguchi experimental design in order to appreciate the effect of both the slurry formulation and drying conditions such as the solid content, the ratio of yttria stabilised zirconia:aerogel added, the amount of dispersant and binder, inlet temperature, atomisation pressure and feeding rate on the median particle size of the resulting spray-dried powder. The latter was found to be affected by all the aforementioned independent variables at different degree of significance and inclination. Based on the derived relationships, an optimised condition to achieve maximum median particle size was then predicted.

Oxygen diffusion in nanocrystalline yttria-stabilized zirconia: the effect of grain boundaries.

PubMed

De Souza, Roger A; Pietrowski, Martha J; Anselmi-Tamburini, Umberto; Kim, Sangtae; Munir, Zuhair A; Martin, Manfred

2008-04-21

The transport of oxygen in dense samples of yttria-stabilized zirconia (YSZ), of average grain size d approximately 50 nm, has been studied by means of 18O/16O exchange annealing and secondary ion mass spectrometry (SIMS). Oxygen diffusion coefficients (D*) and oxygen surface exchange coefficients (k*) were measured for temperatures 673

Impact of oleylamine: Oleic acid ratio on the morphology of yttria nanomaterials

DOE PAGES

Treadwell, LaRico J.; Boyle, Timothy J.; Bell, Nelson S.; ...

2017-03-31

In this paper, the impact on the final morphology of yttria (Y 2O 3) nanoparticles from different ratios (100/0, 90/10, 65/35, and 50/50) of oleylamine (ON) and oleic acid (OA) via a solution precipitation route has been determined. In all instances, powder X-ray diffraction indicated that the cubic Y 2O 3 phase (PDF #00-025-1200) with the space group I-3a (206) had been formed. Analysis of the collected FTIR data revealed the presence of stretches and bends consistent with ON and OA, for all ratios investigated, except the 100/0. Transmission electron microscopy images revealed regular and elongated hexagons were produced formore » the ON (100/0) sample. As OA was added, the nanoparticle morphology changed to lamellar pillars (90/10), then irregular particles (65/35), and finally plates (50/50). The formation of the hexagonal-shaped nanoparticles was determined to be due to the preferential adsorption of ON onto the {101} planes. As OA was added to the reaction mixture, it was found that the {111} planes were preferentially coated, replacing ON from the surface, resulting in the various morphologies noted. The roles of the ratio of ON/OA in the synthesis of the nanocrystals were elucidated in the formation of the various Y 2O 3 morphologies, as well as a possible growth mechanism based on the experimental data.« less

Impact of oleylamine: Oleic acid ratio on the morphology of yttria nanomaterials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Treadwell, LaRico J.; Boyle, Timothy J.; Bell, Nelson S.

In this paper, the impact on the final morphology of yttria (Y 2O 3) nanoparticles from different ratios (100/0, 90/10, 65/35, and 50/50) of oleylamine (ON) and oleic acid (OA) via a solution precipitation route has been determined. In all instances, powder X-ray diffraction indicated that the cubic Y 2O 3 phase (PDF #00-025-1200) with the space group I-3a (206) had been formed. Analysis of the collected FTIR data revealed the presence of stretches and bends consistent with ON and OA, for all ratios investigated, except the 100/0. Transmission electron microscopy images revealed regular and elongated hexagons were produced formore » the ON (100/0) sample. As OA was added, the nanoparticle morphology changed to lamellar pillars (90/10), then irregular particles (65/35), and finally plates (50/50). The formation of the hexagonal-shaped nanoparticles was determined to be due to the preferential adsorption of ON onto the {101} planes. As OA was added to the reaction mixture, it was found that the {111} planes were preferentially coated, replacing ON from the surface, resulting in the various morphologies noted. The roles of the ratio of ON/OA in the synthesis of the nanocrystals were elucidated in the formation of the various Y 2O 3 morphologies, as well as a possible growth mechanism based on the experimental data.« less

Development and evaluation of suspension plasma sprayed yttria stabilized zirconia coatings as thermal barriers

NASA Astrophysics Data System (ADS)

van Every, Kent J.

The insulating effects from thermal barrier coatings (TBCs) in gas turbine engines allow for increased operational efficiencies and longer service lifetimes. Consequently, improving TBCs can lead to enhanced gas turbine engine performance. This study was conducted to investigate if yttria-stabilized zirconia (YSZ) coatings, the standard industrial choice for TBCs, produced from nano-sized powder could provide better thermal insulation than current commericial YSZ coatings generated using micron-sized powders. The coatings for this research were made via the recently developed suspension plasma spraying (SPS) process. With SPS, powders are suspended in a solvent containing dispersing agents; the suspension is then injected directly into a plasma flow that evaporates the solvent and melts the powder while transporting it to the substrate. Although related to the industrial TBC production method of air plasma spraying (APS), SPS has two important differences---the ability to spray sub-micron diameter ceramic particles, and the ability to alloy the particles with chemicals dissolved in the solvent. These aspects of SPS were employed to generate a series of coatings from suspensions containing ˜100 nm diameter YSZ powder particles, some of which were alloyed with neodymium and ytterbium ions from the solvent. The SPS coatings contained columnar structures not observed in APS TBCs; thus, a theory was developed to explain the formation of these features. The thermal conductivity of the coatings was tested to evaluate the effects of these unique microstructures and the effects of the alloying process. The results for samples in the as-sprayed and heat-treated conditions were compared to conventional YSZ TBCs. This comparison showed that, relative to APS YSZ coatings, the unalloyed SPS samples typically exhibited higher as-sprayed and lower heat-treated thermal conductivities. All thermal conductivity values for the alloyed samples were lower than conventional YSZ TBCs

Glass formation, properties, and structure of soda-yttria-silicate glasses

NASA Technical Reports Server (NTRS)

Angel, Paul W.; Hann, Raiford E.

1991-01-01

The glass formation region of the soda yttria silicate system was determined. The glasses within this region were measured to have a density of 2.4 to 3.1 g/cu cm, a refractive index of 1.50 to 1.60, a coefficient of thermal expansion of 7 x 10(exp -6)/C, softening temperatures between 500 and 780 C, and Vickers hardness values of 3.7 to 5.8 GPa. Aqueous chemical durability measurements were made on select glass compositions while infrared transmission spectra were used to study the glass structure and its effect on glass properties. A compositional region was identified which exhibited high thermal expansion, high softening temperatures, and good chemical durability.

RETRACTED: Chemical densification of plasma sprayed yttria stabilized zirconia (YSZ) coatings for high temperature wear and corrosion resistance

NASA Astrophysics Data System (ADS)

Ye, Yaping; Fehr, Karl Thomas; Faulstich, Martin; Wolf, Gerhard

2012-12-01

Plasma-sprayed yttria stabilized zirconia (YSZ) ceramic coatings have been widely used as wear- and corrosion-resistant coatings in high temperature applications and an aggressive environment due to their high hardness, wear resistance, heat and chemical resistance, and low thermal conductivity. The highly porous structure of plasma-sprayed ceramic coatings and their poor adhesion to the substrate usually lead to the coating degradation and failure. In this study, a two-layer system consisting of atmospheric plasma-sprayed 8 wt.% yttria-stabilized zirconia (8YSZ) and Ni-based alloy coatings was post-treated by means of a novel chemical sealing process at moderate temperatures of 600-800 °C. Microstructure characteristics of the YSZ coatings were studied using an electron probe micro-analyzer (EPMA). Results revealed that the ceramic top coat was densified by the precipitated zirconia in the open pores. Therefore, the sealed YSZ coatings exhibit reduced porosity, higher hardness and a better adhesion onto the bond coat. The mechanisms for the sealing process were also proposed.

Grain boundary crystallography in polycrystalline yttria-stabilised cubic zirconia

NASA Astrophysics Data System (ADS)

Kini, Maya K.

2018-07-01

Properties of grain boundaries such as grain boundary energy, mobility and diffusion are reported to depend strongly on their crystallography. While studies on ceramic bicrystals with low Σ misorientations have shown highly ordered structures and low energies, studies on dense polycrystalline ceramics often show the significance of grain boundary planes. In the present study, grain boundary plane distributions were studied for yttria-stabilised cubic zirconia with varying grain sizes using Electron Back Scattered Diffraction technique combined with a stereological approach. Despite nearly isotropic grain boundary plane distributions, a highly anisotropic grain boundary character distribution is observed for specific misorientations. Certain low-energy symmetric tilts such as Σ3 and Σ11 are found to occur with high frequencies across the grain size range studied, leading to an inverse correlation between GB energy and frequency of occurrence, consistent with other ceramics studied in literature.

Kinetic Monte Carlo Simulation of Oxygen and Cation Diffusion in Yttria-Stabilized Zirconia

NASA Technical Reports Server (NTRS)

Good, Brian

2011-01-01

Yttria-stabilized zirconia (YSZ) is of interest to the aerospace community, notably for its application as a thermal barrier coating for turbine engine components. In such an application, diffusion of both oxygen ions and cations is of concern. Oxygen diffusion can lead to deterioration of a coated part, and often necessitates an environmental barrier coating. Cation diffusion in YSZ is much slower than oxygen diffusion. However, such diffusion is a mechanism by which creep takes place, potentially affecting the mechanical integrity and phase stability of the coating. In other applications, the high oxygen diffusivity of YSZ is useful, and makes the material of interest for use as a solid-state electrolyte in fuel cells. The kinetic Monte Carlo (kMC) method offers a number of advantages compared with the more widely known molecular dynamics simulation method. In particular, kMC is much more efficient for the study of processes, such as diffusion, that involve infrequent events. We describe the results of kinetic Monte Carlo computer simulations of oxygen and cation diffusion in YSZ. Using diffusive energy barriers from ab initio calculations and from the literature, we present results on the temperature dependence of oxygen and cation diffusivity, and on the dependence of the diffusivities on yttria concentration and oxygen sublattice vacancy concentration. We also present results of the effect on diffusivity of oxygen vacancies in the vicinity of the barrier cations that determine the oxygen diffusion energy barriers.

Temperature-Dependent Electrical and Micromechanical Properties of Lanthanum Titanate with Additions of Yttria

NASA Technical Reports Server (NTRS)

Goldsby, Jon C.

2010-01-01

Temperature-dependent elastic properties were determined by establishing continuous flexural vibrations in the material at its lowest resonance frequency of 31tHz. The imaginary part of the complex impedance plotted as a function of frequency and temperature reveals a thermally activated peak, which decreases in magnitude as the temperature increases. Additions of yttria do not degrade the electromechanical in particularly the elastic and anelastic properties of lanthanum titanate. Y2O3/La2Ti2O7 exhibits extremely low internal friction and hence may be more mechanical fatigue-resistant at low strains.

Structural and optical properties of electron beam evaporated yttria stabilized zirconia thin films

NASA Astrophysics Data System (ADS)

Kirubaharan, A. Kamalan; Kuppusami, P.; Singh, Akash; Dharini, T.; Ramachandran, D.; Mohandas, E.

2015-06-01

Yttria stabilized zirconia (10 mole % Y2O3) thin films were deposited on quartz substrates using electron beam physical vapor deposition at the substrate temperatures in the range 300 - 973 K. XRD analysis showed cubic crystalline phase of YSZ films with preferred orientation along (111). The surface roughness was found to increase with the increase of deposition temperatures. The optical band gap of ˜5.7 eV was calculated from transmittance curves. The variation in the optical properties is correlated with the changes in the microstructural features of the films prepared as a function of substrate temperature.

Nano-yttria dispersed stainless steel composites composed by the 3 dimensional fiber deposition technique

NASA Astrophysics Data System (ADS)

Verhiest, K.; Mullens, S.; De Wispelaere, N.; Claessens, S.; DeBremaecker, A.; Verbeken, K.

2012-09-01

In this study, oxide dispersion strengthened (ODS) 316L steel samples were manufactured by the 3 dimensional fiber deposition (3DFD) technique. The performance of 3DFD as colloidal consolidation technique to obtain porous green bodies based on yttria (Y2O3) nano-slurries or paste, is discussed within this experimental work. The influence of the sintering temperature and time on sample densification and grain growth was investigated in this study. Hot consolidation was performed to obtain final product quality in terms of residual porosity reduction and final dispersion homogeneity.

Heteroepitaxial growth of tin-doped indium oxide films on single crystalline yttria stabilized zirconia substrates

NASA Astrophysics Data System (ADS)

Kamei, Masayuki; Yagami, Teruyuki; Takaki, Satoru; Shigesato, Yuzo

1994-05-01

Heteroepitaxial growth of tin-doped indium oxide (ITO) film was achieved for the first time by using single crystalline yttria stabilized zirconia (YSZ) as substrates. The epitaxial relationship between ITO film and YSZ substrate was ITO[100]∥YSZ[100]. By comparing the electrical properties of this epitaxial ITO film with that of a randomly oriented polycrystalline ITO film grown on a glass substrate, neither the large angle grain boundaries nor the crystalline orientation were revealed to be dominant in determining the carrier mobility in ITO films.

Grain Boundary Resistivity of Yttria-Stabilized Zirconia at 1400°C

DOE PAGES

Wang, J.; Du, A.; Yang, Di; ...

2013-01-01

Tmore » he grain size dependence of the bulk resistivity of 3 mol% yttria-stabilized zirconia at 1400°C was determined from the effect of a dc electric field E a = 18.1  V/cm on grain growth and the corresponding electric current during isothermal annealing tests. Employing the brick layer model, the present annealing test results were in accordance with extrapolations of the values obtained at lower temperature employing impedance spectroscopy and 4-point-probe dc. he combined values give that the magnitude of the grain boundary resistivity ρ b = 133  ohm-cm. he electric field across the grain boundary width was 28–43 times the applied field for the grain size and current ranges in the present annealing test.« less

Temperature Dependent Electrical and Micromechanical Properties of Lanthanum Titanate with Additions of Yttria

NASA Technical Reports Server (NTRS)

Goldsby, Jon C.

2003-01-01

Lanthanum titanate (La2Ti2O7) a layered distorted perovskite (1) with space group Pna2(sub 1) has been shown to have potential as a high temperature piezoelectric (2). However this highly refractory oxide compound must be consolidated at relatively high temperatures approximately 1400 C. Commercial La2Ti207 powders were mechanically alloyed with additions of Y2O3 to lower the consolidation temperature by 300 C and to provide post processing mechanical stability. Temperature dependent electrical, elastic and anelastic behavior were selected as nondestructive means of evaluating the effects of yttria on the properties of this ferroceramic material.

Epitaxial growth of YBa2Cu3O7 - delta films on oxidized silicon with yttria- and zirconia-based buffer layers

NASA Astrophysics Data System (ADS)

Pechen, E. V.; Schoenberger, R.; Brunner, B.; Ritzinger, S.; Renk, K. F.; Sidorov, M. V.; Oktyabrsky, S. R.

1993-09-01

A study of epitaxial growth of YBa2Cu3O7-δ films on oxidized Si with yttria- and zirconia-based buffer layers is reported. Using substrates with either SiO2 free or naturally oxidized (100) surfaces of Si it was found that a thin SiO2 layer on top of the Si favors high-quality superconducting film formation. Compared to yttria-stabilized ZrO2 (YSZ) single layers, YSZY2O3 double and YSZ/Y2O3YSZ triple layers allows the deposition of thin YBa2Cu3O7-δ films with improved properties including reduced aging effects. In epitaxial YBa2Cu3O7-δ films grown on the double buffer layers a critical temperature Tc(R=0)=89.5 K and critical current densities of 3.5×106 A/cm2 at 77 K and 1×107 A/cm2 at 66 K were reached.

Microstructure and mechanical properties of bulk yttria-partially-stabilized zirconia

NASA Technical Reports Server (NTRS)

Valentine, P. G.; Maier, R. D.; Mitchell, T. E.

1981-01-01

A commercially available bulk 4.5 mole percent yttria-(Y2O3) partially stabilized zirconia (PSZ) was studied by light microscopy, X-ray analysis, microhardness measurement, and fracture toughness testing. The growth of the precipitates and the phase transformations were studied as a function of aging in air at 1500 C. Aging curves were constructed for both the as received and the solution annealed and quenched materials; the curves showed hardness peaks at 1397 and 1517 Kg/sq mm respectively. The rectangular plate shaped tetragonal precipitates were found to have a 110 habit plane. A total of twelve different types of tetragonal precipitates were found. Grinding of the Y2O3 PSZ into powder did not cause a significant amount of metastable tetragonal precipitates to transform into the monoclinc phase, thus indicating that transformation toughening is not a significant mechanism for the material.

Controlling Microstructure of Yttria-Stabilized Zirconia Prepared from Suspensions and Solutions by Plasma Spraying with High Feed Rates

NASA Astrophysics Data System (ADS)

Musalek, Radek; Medricky, Jan; Tesar, Tomas; Kotlan, Jiri; Pala, Zdenek; Lukac, Frantisek; Illkova, Ksenia; Hlina, Michal; Chraska, Tomas; Sokolowski, Pawel; Curry, Nicholas

2017-12-01

Introduction of suspension and solution plasma spraying led to a breakthrough in the deposition of yttria-stabilized zirconia (YSZ) coatings and enabled preparation of new types of layers. However, their deposition with high feed rates needed, for example, for the deposition of thermal barrier coatings (TBCs) on large-scale components, is still challenging. In this study, possibility of high-throughput plasma spraying of YSZ coatings is demonstrated for the latest generation of high-enthalpy hybrid water-stabilized plasma (WSP-H) torch technology. The results show that microstructure of the coatings prepared by WSP-H may be tailored for specific applications by the choice of deposition conditions, in particular formulation of the liquid feedstock. Porous and columnar coatings with low thermal conductivity (0.5-0.6 W/mK) were prepared from commercial ethanol-based suspension. Dense vertically cracked coatings with higher thermal conductivity but also higher internal cohesion were deposited from suspension containing ethanol/water mixture and coarser YSZ particles. Spraying of solution formulated from diluted zirconium acetate and yttrium nitrate hexahydrate led also to the successful deposition of YSZ coating combining regions of porous and denser microstructure and providing both low thermal conductivity and improved cohesion of the coating. Enthalpy content, liquid-plasma interaction and coating buildup mechanisms are also discussed.

Radiation damage in cubic ZrO 2 and yttria-stabilized zirconia from molecular dynamics simulations

DOE PAGES

Aidhy, Dilpuneet S.; Zhang, Yanwen; Weber, William J.

2014-11-20

Here, we perform molecular dynamics simulation on cubic ZrO 2 and yttria-stabilized zirconia (YSZ) to elucidate defect cluster formation resulting from radiation damage, and evaluate the impact of Y-dopants. Interstitial clusters composed of split-interstitial building blocks, i.e., Zr-Zr or Y-Zr are formed. Moreover, oxygen vacancies control cation defect migration; in their presence, Zr interstitials aggregate to form split-interstitials whereas in their absence Zr interstitials remain immobile, as isolated single-interstitials. Y-doping prevents interstitial cluster formation due to sequestration of oxygen vacancies.

Microscopic observation of laser glazed yttria-stabilized zirconia coatings

NASA Astrophysics Data System (ADS)

Morks, M. F.; Berndt, C. C.; Durandet, Y.; Brandt, M.; Wang, J.

2010-08-01

Thermal barrier coatings (TBCs) are frequently used as insulation system for hot components in gas-turbine, combustors and power plant industries. The corrosive gases which come from combustion of low grade fuels can penetrate into the TBCs and reach the metallic components and bond coat and cause hot corrosion and erosion damage. Glazing the top coat by laser beam is advanced approach to seal TBCs surface. The laser beam has the advantage of forming a dense thin layer composed of micrograins. Plasma-sprayed yttria-stabilized zirconia (YSZ) coating was glazed with Nd-YAG laser at different operating conditions. The surface morphologies, before and after laser treatment, were investigated by scanning electron microscopy. Laser beam assisted the densification of the surface by remelting a thin layer of the exposed surface. The laser glazing converted the rough surface of TBCs into smooth micron-size grains with size of 2-9 μm and narrow grain boundaries. The glazed surfaces showed higher Vickers hardness compared to as-sprayed coatings. The results revealed that the hardness increases as the grain size decreases.

Determination of oxygen vacancy limit in Mn substituted yttria stabilized zirconia

NASA Astrophysics Data System (ADS)

Stepień, Joanna; Sikora, Marcin; Kapusta, Czesław; Pomykalska, Daria; Bućko, Mirosław M.

2018-05-01

A series of Mnx(Y0.148Zr0.852)1-xO2-δ ceramics was systematically studied by means of X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) and DC magnetic susceptibility. The XAS and XES results show the changes in manganese oxidation state and a gradual evolution of the local atomic environment around Mn ions upon increasing dopant contents, which is due to structural relaxation caused by the growing amount of oxygen vacancies. Magnetic susceptibility measurements reveal that Mn3O4 precipitates are formed for x ≥ 0.1 and enable independent determination of the actual quantity of Mn ions dissolved in Yttria Stabilized Zirconia (YSZ) solid solution. We show that the amount of oxygen vacancies generated by manganese doping into YSZ is limited to ˜0.17 per formula unit.

Yttria stabilized zirconia transparent films prepared by chemical vapor deposition

NASA Astrophysics Data System (ADS)

Yamane, Hisanori; Hirai, Toshio

1989-04-01

Yttria stabilized zirconia (YSZ) transparent films were prepared on quartz glass substrates at the temperature of 1375 K under atmospheric pressure using ZrCl 4, YCl 3 and O 2 gases as source materials. The growth rate of the film thickness was 1.5 to 2.0 μm/h. Cubic YSZ films were obtained at the value of x between 20 to 60, where x is defined by x( wt%) = YCl3×100/( YCl3+ ZrCl4). The lattice parameter of the cubic YSZ increased from 5.14 to 5.19 Å with the increase of x. Transparent films were obtained at the interval where the x value was between 20 to 45. The (100) plane of YSZ is oriented parallel to the surface of the substrate. For transparent film obtained at x = 29 (1.5 μm in thickness) the optical transmittance was 50-70% in the wavelength range of 250-800 nm.

Infrared Radiative Properties of Yttria-Stabilized Zirconia Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Eldridge, Jeff I.; Spuckler, Charles M.; Street, Ken W.; Markham, Jim R.; Gray, Hugh R. (Technical Monitor)

2002-01-01

The infrared (IR) transmittance and reflectance of translucent thermal barrier coatings (TBCs) have important implications for both the performance of these coatings as radiation barriers and emitters as well as affecting measurements of TBC thermal conductivity, especially as TBCs are being pushed to higher temperatures. In this paper, the infrared spectral directional-hemispherical transmittance and reflectance of plasma-sprayed 8wt% yttria-stabilized zirconia (8YSZ) TBCs are reported. These measurements are compared to those for single crystal YSZ specimens to show the effects of the plasma-sprayed coating microstructure. It is shown that the coatings exhibit negligible absorption at wavelengths up to about 5 micrometers, and that internal scattering rather than surface reflections dominates the hemispherical reflectance. The translucent nature of the 8YSZ TBCs results in the absorptance/emittance and reflectance of TBC-coated substrates depending on the TBC thickness, microstructure, as well as the radiative properties of the underlying substrate. The effects of these properties on TBC measurements and performance are discussed.

Luminescent sensors for tracking spatial particle distributions in an explosion

NASA Astrophysics Data System (ADS)

Anderson, Benjamin R.; Gunawidjaja, Ray; Diez-y-Riega, Helena; Eilers, Hergen; Svingala, Forrest R.; Daniels, Amber; Lightstone, James M.

2017-01-01

We previously developed and tested thermally sensitive particles that, when seeded into an explosive event, flow with the expanding post-detonation fireball and provide ex-situ measurements of this thermal environment. This current work presents the development and testing of tracking particles that are used in concert with the thermally sensitive particles to encode the initial positions of materials recovered for ex-situ analysis. These tracking sensors consist of fully-crystallized (c) rare-earth-doped yttria particles such as c-Dy:Y2O3, c-Sm:Y2O3, and c-Er,Yb:Y2O3. The temperature sensors consist of mixtures of precursor (p) and fully crystallized materials such as p-Eu:Y2O3/c-Tb:Y2O3 or p-Eu:ZrO2. Three mixtures containing one of the tracking sensors and one of the temperature sensing mixtures are placed at different locations within the chamber. Post-detonation, the tracking particles in the debris are excited by 355 nm light, resulting in different color luminescence, and allowing for potential visual inspection of the particle distribution originating from the different locations. Meanwhile, the temperature is determined from spectral changes of the precursor sensor materials or by comparison of the precursor sensor materials with the Tb:Y2O3 intensity reference.

Mixed conductivity, structural and microstructural characterization of titania-doped yttria tetragonal zirconia polycrystalline/titania-doped yttria stabilized zirconia composite anode matrices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colomer, M.T., E-mail: tcolomer@icv.csic.e; Maczka, M.

2011-02-15

Taking advantage of the fact that TiO{sub 2} additions to 8YSZ cause not only the formation of a titania-doped YSZ solid solution but also a titania-doped YTZP solid solution, composite materials based on both solutions were prepared by solid state reaction. In particular, additions of 15 mol% of TiO{sub 2} give rise to composite materials constituted by 0.51 mol fraction titania-doped yttria tetragonal zirconia polycrystalline and 0.49 mol fraction titania-doped yttria stabilized zirconia (0.51TiYTZP/0.49TiYSZ). Furthermore, Y{sub 2}(Ti{sub 1-y}Zr{sub y}){sub 2}O{sub 7} pyrochlore is present as an impurity phase with y close to 1, according to FT-Raman results. Lower and highermore » additions of titania than that of 15 mol%, i.e., x=0, 5, 10, 20, 25 and 30 mol% were considered to study the evolution of 8YSZ phase as a function of the TiO{sub 2} content. Furthermore, zirconium titanate phase (ZrTiO{sub 4}) is detected when the titania content is equal or higher than 20 mol% and this phase admits Y{sub 2}O{sub 3} in solid solution according to FE-SEM-EDX. The 0.51TiYTZP/0.49TiYSZ duplex material was selected in this study to establish the mechanism of its electronic conduction under low oxygen partial pressures. In the pO{sub 2} range from 0.21 to 10{sup -7.5} atm. the conductivity is predominantly ionic and constant over the range and its value is 0.01 S/cm. The ionic plus electronic conductivity is 0.02 S/cm at 1000 {sup o}C and 10{sup -12.3} atm. Furthermore, the onset of electronic conductivity under reducing conditions exhibits a -1/4 pO{sub 2} dependence. Therefore, it is concluded that the n-type electronic conduction in the duplex material can be due to a small polaron-hopping between Ti{sup 3+} and Ti{sup 4+}. -- Graphical abstract: FE-SEM micrograph of a polished and thermal etched surface of a Ti-doped YTZP/Ti-doped YSZ composite material. Display Omitted Research highlights: {yields} Ti-doped YTZP/Ti-doped YSZ composite materials are mixed conductors

Defect Clustering and Nano-Phase Structure Characterization of Multi-Component Rare Earth Oxide Doped Zirconia-Yttria Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Chen, Yuan L.; Miller, Robert A.

2003-01-01

Advanced oxide thermal barrier coatings have been developed by incorporating multi-component rare earth oxide dopants into zirconia-yttria to effectively promote the creation of the thermodynamically stable, immobile oxide defect clusters and/or nano-scale phases within the coating systems. The presence of these nano-sized defect clusters has found to significantly reduce the coating intrinsic thermal conductivity, improve sintering resistance, and maintain long-term high temperature stability. In this paper, the defect clusters and nano-structured phases, which were created by the addition of multi-component rare earth dopants to the plasma-sprayed and electron-beam physical vapor deposited thermal barrier coatings, were characterized by high-resolution transmission electron microscopy (TEM). The defect cluster size, distribution, crystallographic and compositional information were investigated using high-resolution TEM lattice imaging, selected area diffraction (SAD), electron energy-loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) analysis techniques. The results showed that substantial defect clusters were formed in the advanced multi-component rare earth oxide doped zirconia- yttria systems. The size of the oxide defect clusters and the cluster dopant segregation was typically ranging from 5 to 50 nm. These multi-component dopant induced defect clusters are an important factor for the coating long-term high temperature stability and excellent performance.

Defect Clustering and Nano-Phase Structure Characterization of Multi-Component Rare Earth Oxide Doped Zirconia-Yttria Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Chen, Yuan L.; Miller, Robert A.

1990-01-01

Advanced oxide thermal barrier coatings have been developed by incorporating multi- component rare earth oxide dopants into zirconia-yttria to effectively promote the creation of the thermodynamically stable, immobile oxide defect clusters and/or nano-scale phases within the coating systems. The presence of these nano-sized defect clusters has found to significantly reduce the coating intrinsic thermal conductivity, improve sintering resistance, and maintain long-term high temperature stability. In this paper, the defect clusters and nano-structured phases, which were created by the addition of multi-component rare earth dopants to the plasma- sprayed and electron-beam physical vapor deposited thermal barrier coatings, were characterized by high-resolution transmission electron microscopy (TEM). The defect cluster size, distribution, crystallographic and compositional information were investigated using high-resolution TEM lattice imaging, selected area diffraction (SAD), and energy dispersive spectroscopy (EDS) analysis techniques. The results showed that substantial defect clusters were formed in the advanced multi-component rare earth oxide doped zirconia-yttria systems. The size of the oxide defect clusters and the cluster dopant segregation was typically ranging fiom 5 to 50 nm. These multi-component dopant induced defect clusters are an important factor for the coating long-term high temperature stability and excellent performance.

Synthesis of multi-hierarchical structured yttria-stabilized zirconia powders and their enhanced thermophysical properties

NASA Astrophysics Data System (ADS)

Cao, Fengmei; Gao, Yanfeng; Chen, Hongfei; Liu, Xinling; Tang, Xiaoping; Luo, Hongjie

2013-06-01

Multi-hierarchical structured yttria-stabilized zirconia (YSZ) powders were successfully synthesized by a hydrothermal-calcination process. The morphology, crystallinity, and microstructure of the products were characterized by SEM, XRD, TEM, and BET. A possible formation mechanism of the unique structure formed during hydrothermal processing was also investigated. The measured thermophysical results indicated that the prepared YSZ powders had a low thermal conductivity (0.63-1.27 W m-1 K-1), good short-term high-temperature stability up to 1300 °C. The influence of the morphology and microstructure on their thermophysical properties was briefly discussed. The unique multi-hierarchical structure makes the prepared YSZ powders candidates for use in enhanced applications involving thermal barrier coatings.

Air Plasma-Sprayed Yttria and Yttria-Stabilized Zirconia Thermal Barrier Coatings Subjected to Calcium-Magnesium-Alumino-Silicate (CMAS)

NASA Astrophysics Data System (ADS)

Li, Wenshuai; Zhao, Huayu; Zhong, Xinghua; Wang, Liang; Tao, Shunyan

2014-08-01

Yttria (Y2O3) and zirconia (ZrO2) stabilized by 8 and 20 wt.%Y2O3 thermal barrier coatings (TBCs) subjected to calcium-magnesium-alumino-silicate (CMAS) have been investigated. Free-standing Y2O3, 8 and 20 wt.%YSZ coatings covered with synthetic CMAS slurry were heated at 1300 °C in air for 24 h in order to assess the effect of Y2O3 on the corrosion resistance of the coatings subjected to CMAS. The microstructures and phase compositions of the coatings were characterized by SEM, EDS, XRD, RS, and TEM. TBCs with higher Y2O3 content exhibited better CMAS corrosion resistance. Phase transformation of ZrO2 from tetragonal (t) to monoclinic (m) occurred during the interaction of 8YSZ TBCs and CMAS, due to the depletion of Y2O3 in the coating. Some amounts of original c-ZrO2 still survived in 20YSZ TBCs along with a small amount of m-ZrO2 that appeared after reaction with CMAS. Furthermore, Y2O3 coating was found to be particularly highly effective in resisting the penetration of molten CMAS glass at high temperature (1300 °C). This may be ascribed to the formation of sealing layers composed of Y-apatite phase [based on Ca4Y6 (SiO4)6O and Y4.67(SiO4)3O] by the high-temperature chemical interactions of Y2O3 coating and CMAS glass.

Luminescent Sensors for Tracking Spatial Particle Distribution in an Explosion

NASA Astrophysics Data System (ADS)

Eilers, Hergen; Gunawidjaja, Ray; Diez-Y-Riega, Helena; Svingala, Forrest; Daniels, Amber; Lightstone, James; Washington State University Collaboration; Nswc Iheodtd Collaboration

2015-06-01

We previously developed and tested thermally sensitive particles that, when seeded into an explosive event, flow with the expanding post-detonation fireball and provide ex-situ measurements of this thermal environment. This current work presents the development and testing of tracking particles that are used in concert with the thermally sensitive particles to encode the initial positions of materials recovered for ex-situ analysis. These tracking sensors consist of fully-crystallized (c) rare-earth-doped yttria particles such as c-Dy:Y2O3, c-Sm:Y2O3, and c-Er,Yb:Y2O3. The temperature sensors consist of mixtures of precursor (p) and fully crystallized materials such as p-Eu:Y2O3/c-Tb:Y2O3 orp-Eu:ZrO2/c-Tb:Y2O3. Three mixtures containing one of the tracking sensors and one of the temperature sensing mixtures are placed at different locations within the chamber. Post-detonation, the tracking particles in the debris are excited by 365 nm light, resulting in different color luminescence, and allowing for potential visual inspection of the particle distribution originating from the different locations. Meanwhile, the temperature is determined from spectral changes of the precursor sensor materials or by comparison of the precursor sensor materials with the Tb:Y2O3 intensity reference. Defense Threat Reduction Agency, HDTRA1-10-1-0005.

Microstructure and mechanical properties of bulk yttria-partially-stabilized zirconia

NASA Technical Reports Server (NTRS)

Valentine, P. G.; Maier, R. D.; Mitchell, T. E.

1981-01-01

A commercially available bulk 4.5 mole percent yttria-Y2O3)-partially-stabilized zirconia (PSZ) was studied by light microscopy, X-ray analysis, microhardness measurement, and fracture toughness testing. The growth of the precipitates and the phase transformations were studied as a function of aging in air at 1500 C. Aging cuves were constructed for both the as-received and the solution-annealed-and-quenched materials; the curves showed hardness peaks at 1397 and 1517 kg/sq mm, respectively. A total of twelve different types of tetragonal precipitates were found. The rectangular plate-shaped tetragonal precipitates were found to have a (110) habit plane. Grinding of the Y2O3 PSZ into powder did not cause a significant amount of metastable tetragonal precipitates to transform into the monoclinic phase, thus indicating that transformation toughening is not a significant mechanism for the material. The fracture toughness of the aged and of the unaged solution-annealed-and-quenched PSZ was found to be between 2 and 3 MN/cu m/2.

The effect of Al intermediate layer on thermal resistance of EB-PVD yttria-stabilized zirconia coatings on titanium substrate

NASA Astrophysics Data System (ADS)

Panin, Alexey; Panin, Victor; Kazachenok, Marina; Shugurov, Artur; Sinyakova, Elena; Martynov, Sergey; Rusyaev, Andrey; Kasterov, Artur

2017-12-01

The yttria-stabilized zirconia coatings sprayed on titanium substrates by the electron beam physical vapor deposition were subjected to thermal annealing in air at 1000°C for 1, 30 and 60 min. The delamination and fracture of the coatings are studied by the scanning electron microscopy and X-ray diffraction. It is shown that a magnetron sputtered Al interlayer between the coating and the substrate considerably improves the thermal resistance of ceramic coatings.

Fabrication of biaxially oriented YBCO on (001) biaxially oriented yttria-stabilized-zirconia on polycrystalline substrates

NASA Astrophysics Data System (ADS)

Arendt, P.; Foltyn, S.; Wu, Xin Di; Townsend, J.; Adams, C.; Hawley, M.; Tiwari, P.; Maley, M.; Willis, J.; Moseley, D.

Ion-assisted, ion-beam sputter deposition is used to obtain (001) biaxially oriented films of cubic yttria stabilized zirconia (YSZ) on polycrystalline metal substrates. Yttrium barium copper oxide (YBCO) is then heteroepitaxially pulse laser deposited onto the YSZ. Phi scans of the films show the full-width-half maxima of the YSZ (202) and the YBCO (103) reflections to be 14 deg and 10 deg, respectively. Our best dc transport critical current density measurement for the YBCO is 800,000 A/sq cm at 75 K and 0 T. At 75 K, the total dc transport current in a 1 cm wide YBCO film is 23 A.

A facile approach to manufacturing non-ionic surfactant nanodipsersions using proniosome technology and high-pressure homogenization.

PubMed

Najlah, Mohammad; Hidayat, Kanar; Omer, Huner K; Mwesigwa, Enosh; Ahmed, Waqar; AlObaidy, Kais G; Phoenix, David A; Elhissi, Abdelbary

2015-03-01

In this study, a niosome nanodispersion was manufactured using high-pressure homogenization following the hydration of proniosomes. Using beclometasone dipropionate (BDP) as a model drug, the characteristics of the homogenized niosomes were compared with vesicles prepared via the conventional approach of probe-sonication. Particle size, zeta potential, and the drug entrapment efficiency were similar for both size reduction mechanisms. However, high-pressure homogenization was much more efficient than sonication in terms of homogenization output rate, avoidance of sample contamination, offering a greater potential for a large-scale manufacturing of noisome nanodispersions. For example, high-pressure homogenization was capable of producing small size niosomes (209 nm) using a short single-step of size reduction (6 min) as compared with the time-consuming process of sonication (237 nm in >18 min) and the BDP entrapment efficiency was 29.65% ± 4.04 and 36.4% ± 2.8. In addition, for homogenization, the output rate of the high-pressure homogenization was 10 ml/min compared with 0.83 ml/min using the sonication protocol. In conclusion, a facile, applicable, and highly efficient approach for preparing niosome nanodispersions has been established using proniosome technology and high-pressure homogenization.

The Single-Crystal Elasticity of Yttria (Y2O3) to High Temperature

NASA Technical Reports Server (NTRS)

Kriven, Waltraud M.; Palko, James W.; Sinogeikin, Stanislav V.; Bass, Jay D.; Sayir, Ali; Levine, Stanley R. (Technical Monitor)

2000-01-01

The single-crystal elastic moduli of yttria have been measured by Brillouin spectroscopy up to 1200 C. The room temperature values obtained are C11 = 223.6 +/- 0.6 GPa, C44 = 74.6 +/- 0.5 GPa, and C12 = 112.4 +/- 1.0 GPa. The resulting bulk and (Voigt-Reuss-Hill) shear moduli are K = 149.5 +/- 1.0 GPa and G(sub VRH) = 66.3 +/- 0.8 GPa, respectively. These agree much more closely with experimental values reported for polycrystalline samples than do previous single-crystal measurements. Linear least squares regressions to the variation of bulk and shear moduli with temperature result in derivatives of dK/dT = -17 +/- 2 MPa/degC and dG(sub VRH)/dT = -8 +/- 2 MPa/degC. Elastic anisotropy was found to remain essentially constant over the temperature range studied.

Brazing of Stainless Steels to Yttria Stabilized Zirconia (YSZ) Using Silver -Base Brazes

NASA Technical Reports Server (NTRS)

Singh, Mrityunjay; Shpargel, Tarah P.; Asthana, Rajiv

2005-01-01

Three silver-base brazes containing either noble metal palladium (Palcusil-10 and Palcusil-15) or active metal titanium (Ticusil) were evaluated for high-temperature oxidation resistance, and their effectiveness in joining yttria stabilized zirconia (YSZ) to a corrosion-resistant ferritic stainless steel. Thermogravimetric analysis (TGA), and optical- and scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS) were used to evaluate the braze oxidation behavior and the structure and chemistry of the YSZ/braze/steel joints. The effect of the braze type and processing conditions on the interfacial microstructure and composition of the joint regions is discussed with reference to the chemical changes that occur at the interface. It was found that chemical interdiffusion of the constituents of YSZ, steel and the brazes led to compositional changes and/or interface reconstruction, and metallurgically sound joints.

UV stabilization of wood by nano metal oxides dispersed in propylene glycol.

PubMed

Nair, Sreeja; Nagarajappa, Giridhar B; Pandey, Krishna K

2018-06-01

Nanoparticles of some of the metal oxides are known to have high UV protective efficiency. The UV filtering efficiency of nanoparticles invariably depends on their size and stability in the dispersion. In the present work, a stable dispersion of nanoparticles of three metal oxides, zinc oxide (ZnO), cerium oxide (CeO 2 ) and titanium dioxide (TiO 2 ), was prepared in propylene glycol (PG) using ultrasonication. The method is easy and useful as no additional surfactant or dispersant is needed. The particle size and its distribution was confirmed by Scanning Electron Microscopy and Dynamic Light Scattering. The stability of dispersion was assessed by UV-visible absorption spectroscopy. The UV stability of wood surfaces of Wrightia tinctoria coated with nanodispersions of ZnO, CeO 2 and TiO 2 was evaluated under laboratory conditions in an accelerated weathering tester. Changes in the colour and FTIR spectra of exposed specimens were measured periodically. Rapid colour darkening (yellowing) was observed in uncoated and PG coated specimens. In contrast, nanodispersion coated specimens prevented photo-yellowing considerably with significant reduction in colour changes examined by CIE L*, a*, b* and ΔE*. Increase in concentration of nanoparticles in the dispersion imparted higher resistance to UV induced degradation. However, increased concentration of nanoparticles reduced the transparency of the coating. FTIR analysis indicated rapid degradation of lignin in uncoated and PG coated specimens due to UV exposure. Coating of wood surfaces with nanodispersions restricted lignin degradation. The study also demonstrates the potential of propylene glycol as a dispersant for developing stable and efficient UV protective nanodispersions for wood coating. Copyright © 2018 Elsevier B.V. All rights reserved.

Investigations on composition and morphology of electrochemical alumina and alumina yttria stabilised zirconia deposits

NASA Astrophysics Data System (ADS)

El Hajjaji, S.; Manov, S.; Roy, J.; Aigouy, T.; Ben Bachir, A.; Aries, L.

2001-08-01

Conversion coatings modified by deposits of electrolytic alumina added or not with yttria and/or zirconia, have been studied which are well known for their resistance to chemical attack and high temperature. Conversion coating, characterised by a particular morphology and strong interfacial adhesion with the substrate, facilitate the electrochemical deposition of ceramic layers and enhance their adhesion to the substrate. Zirconia-alumina coating behaviour at 1000°C is similar to that of alumina coating; from 800°C, the chromium diffuses from the stainless steel through the electrolytic refractory coating up to the external interface, provokes discontinuities and can modify its protective character. Yttrium stabilises the cubic and the tetragonal form of the zirconia; so, during cooling, the phase transformation near 1000°C of tetragonal zirconia to monoclinic form cannot take place.

Long-time aging in 3 mol.% yttria-stabilized tetragonal zirconia polycrystals at human body temperature.

PubMed

Keuper, Melanie; Berthold, Christoph; Nickel, Klaus Georg

2014-02-01

We present new findings on the low-temperature degradation of yttria-stabilized zirconia at 37°C over several years and at high and low partial pressures of water. With the aid of focused ion beam cross-section confirmation studies we are able to show an extensive linear, continuous degradation without retardation, even at low temperatures and low water pressures. The characteristic layer growth and its inferred rate constant imply a lifetime of tens of years under simple tension and open the possibility of studying the longevity of these ceramics more rigorously. In addition, we show reproducibility complications of accelerated aging tests by the use of different autoclaves and possible implications for standardized procedures. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Mechanical properties, electrochemical corrosion and in-vitro bioactivity of yttria stabilized zirconia reinforced hydroxyapatite coatings prepared by gas tunnel type plasma spraying.

PubMed

Yugeswaran, S; Yoganand, C P; Kobayashi, A; Paraskevopoulos, K M; Subramanian, B

2012-05-01

Yttria stabilized zirconia reinforced hydroxyapatite coatings were deposited by a gas tunnel type plasma spray torch under optimum spraying conditions. For this purpose, 10, 20 and 30 wt% of yttria stabilized zirconia (YSZ) powders were premixed individually with hydroxyapatite (HA) powder and were used as the feedstocks for the coatings. The effect of YSZ reinforcement on the phase formation and mechanical properties of the coatings such as hardness, adhesive strength and sliding wear rates was examined. The results showed that the reinforcement of YSZ in HA could significantly enhance the hardness and adhesive strength of the coatings. The potentiodynamic polarization and impedance measurements showed that the reinforced coatings exhibited superior corrosion resistance compared to the HA coating in SBF solution. Further the results of the bioactivity test conducted by immersion of coatings in SBF showed that after 10 days of immersion of the obtained coatings with all the above compositions commonly exhibited the onset of bioactive apatite formation except for HA+10%YSZ coating. The cytocompatibility was investigated by culturing the green fluorescent protein (GFP)-labeled marrow stromal cells (MSCs) on the coating surface. The cell culture results revealed that the reinforced coatings have superior cell growth than the pure HA coatings. Copyright © 2012. Published by Elsevier Ltd.

Improving the reliability of road materials based on micronized sulfur composites

NASA Astrophysics Data System (ADS)

Abdrakhmanova, K. K.

2015-01-01

The work contains the results of a nano-structural modification of sulfur that prevents polymorphic transformations from influencing the properties of sulfur composites where sulfur is present in a thermodynamic stable condition that precludes destruction when operated. It has been established that the properties of sulfur-based composite materials can be significantly improved by modifying sulfur and structuring sulfur binder by nano-dispersed fiber particles and ultra-dispersed state filler. The paper shows the possibility of modifying Tengiz sulfur by its fragmenting which ensures that the structured sulfur is structurally changed and stabilized through reinforcement by ultra-dispersed fiber particles allowing the phase contact area to be multiplied. Interaction between nano-dispersed fibers of chrysotile asbestos and sulfur ensures the implementation of the mechanical properties of chrysotile asbestos tubes in reinforced composite and its integrity provided that the surface of chrysotile asbestos tubes are highly moistened with molten sulfur and there is high adhesion between the tubes and the matrix that, in addition to sulfur, contains limestone microparticles. Ability to apply materials in severe operation conditions and possibility of exposure in both aggressive medium and mechanical loads makes produced sulfur composites required by the road construction industry.

Radiation tolerance of nanocrystalline ceramics: insights from Yttria Stabilized Zirconia.

PubMed

Dey, Sanchita; Drazin, John W; Wang, Yongqiang; Valdez, James A; Holesinger, Terry G; Uberuaga, Blas P; Castro, Ricardo H R

2015-01-13

Materials for applications in hostile environments, such as nuclear reactors or radioactive waste immobilization, require extremely high resistance to radiation damage, such as resistance to amorphization or volume swelling. Nanocrystalline materials have been reported to present exceptionally high radiation-tolerance to amorphization. In principle, grain boundaries that are prevalent in nanomaterials could act as sinks for point-defects, enhancing defect recombination. In this paper we present evidence for this mechanism in nanograined Yttria Stabilized Zirconia (YSZ), associated with the observation that the concentration of defects after irradiation using heavy ions (Kr(+), 400 keV) is inversely proportional to the grain size. HAADF images suggest the short migration distances in nanograined YSZ allow radiation induced interstitials to reach the grain boundaries on the irradiation time scale, leaving behind only vacancy clusters distributed within the grain. Because of the relatively low temperature of the irradiations and the fact that interstitials diffuse thermally more slowly than vacancies, this result indicates that the interstitials must reach the boundaries directly in the collision cascade, consistent with previous simulation results. Concomitant radiation-induced grain growth was observed which, as a consequence of the non-uniform implantation, caused cracking of the nano-samples induced by local stresses at the irradiated/non-irradiated interfaces.

Radiation Tolerance of Nanocrystalline Ceramics: Insights from Yttria Stabilized Zirconia

PubMed Central

Dey, Sanchita; Drazin, John W.; Wang, Yongqiang; Valdez, James A.; Holesinger, Terry G.; Uberuaga, Blas P.; Castro, Ricardo H. R.

2015-01-01

Materials for applications in hostile environments, such as nuclear reactors or radioactive waste immobilization, require extremely high resistance to radiation damage, such as resistance to amorphization or volume swelling. Nanocrystalline materials have been reported to present exceptionally high radiation-tolerance to amorphization. In principle, grain boundaries that are prevalent in nanomaterials could act as sinks for point-defects, enhancing defect recombination. In this paper we present evidence for this mechanism in nanograined Yttria Stabilized Zirconia (YSZ), associated with the observation that the concentration of defects after irradiation using heavy ions (Kr+, 400 keV) is inversely proportional to the grain size. HAADF images suggest the short migration distances in nanograined YSZ allow radiation induced interstitials to reach the grain boundaries on the irradiation time scale, leaving behind only vacancy clusters distributed within the grain. Because of the relatively low temperature of the irradiations and the fact that interstitials diffuse thermally more slowly than vacancies, this result indicates that the interstitials must reach the boundaries directly in the collision cascade, consistent with previous simulation results. Concomitant radiation-induced grain growth was observed which, as a consequence of the non-uniform implantation, caused cracking of the nano-samples induced by local stresses at the irradiated/non-irradiated interfaces. PMID:25582769

Radiation tolerance of nanocrystalline ceramics: Insights from yttria stabilized zirconia

DOE PAGES

Dey, Sanchita; Drazin, John W.; Wang, Yongqiang; ...

2015-01-13

Materials for applications in hostile environments, such as nuclear reactors or radioactive waste immobilization, require extremely high resistance to radiation damage, such as resistance to amorphization or volume swelling. Nanocrystalline materials have been reported to present exceptionally high radiation-tolerance to amorphization. In principle, grain boundaries that are prevalent in nanomaterials could act as sinks for point-defects, enhancing defect recombination. In this paper we present evidence for this mechanism in nanograined Yttria Stabilized Zirconia (YSZ), associated with the observation that the concentration of defects after irradiation using heavy ions (Kr⁺, 400 keV) is inversely proportional to the grain size. HAADF imagesmore » suggest the short migration distances in nanograined YSZ allow radiation induced interstitials to reach the grain boundaries on the irradiation time scale, leaving behind only vacancy clusters distributed within the grain. Because of the relatively low temperature of the irradiations and the fact that interstitials diffuse thermally more slowly than vacancies, this result indicates that the interstitials must reach the boundaries directly in the collision cascade, consistent with previous simulation results. Concomitant radiation-induced grain growth was observed which, as a consequence of the non-uniform implantation, caused cracking of the nano-samples induced by local stresses at the irradiated/non-irradiated interfaces.« less

Rapid, cool sintering of wet processed yttria-stabilized zirconia ceramic electrolyte thin films.

PubMed

Park, Jun-Sik; Kim, Dug-Joong; Chung, Wan-Ho; Lim, Yonghyun; Kim, Hak-Sung; Kim, Young-Beom

2017-09-29

Here we report a photonic annealing process for yttria-stabilized zirconia films, which are one of the most well-known solid-state electrolytes for solid oxide fuel cells (SOFCs). Precursor films were coated using a wet-chemical method with a simple metal-organic precursor solution and directly annealed at standard pressure and temperature by two cycles of xenon flash lamp irradiation. The residual organics were almost completely decomposed in the first pre-annealing step, and the fluorite crystalline phases and good ionic conductivity were developed during the second annealing step. These films showed properties comparable to those of thermally annealed films. This process is much faster than conventional annealing processes (e.g. halogen furnaces); a few seconds compared to tens of hours, respectively. The significance of this work includes the treatment of solid-state electrolyte oxides for SOFCs and the demonstration of the feasibility of other oxide components for solid-state energy devices.

Microstructure, crystallization and shape memory behavior of titania and yttria co-doped zirconia

DOE PAGES

Zeng, Xiao Mei; Du, Zehui; Schuh, Christopher A.; ...

2015-12-17

Small volume zirconia ceramics with few or no grain boundaries have been demonstrated recently to exhibit the shape memory effect. To explore the shape memory properties of yttria doped zirconia (YDZ), it is desirable to develop large, microscale grains, instead of submicron grains that result from typical processing of YDZ. In this paper, we have successfully produced single crystal micro-pillars from microscale grains encouraged by the addition of titania during processing. Titania has been doped into YDZ ceramics and its effect on the grain growth, crystallization and microscale elemental distribution of the ceramics have been systematically studied. With 5 mol%more » titania doping, the grain size can be increased up to ~4 μm, while retaining a large quantity of the desired tetragonal phase of zirconia. Finally, micro-pillars machined from tetragonal grains exhibit the expected shape memory effects where pillars made from titania-free YDZ would not.« less

Adsorption as a method of doping 3-mol%-yttria-stabilized zirconia powder with copper oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seidensticker, J.R.; Mayo, M.J.; Osseo-Asare, K.

The adsorption behavior of Cu[sup 2+] on 3-mol%-yttria-stabilized tetragonal zirconia polycrystalline (3Y-TZP) powder was studied. There is a window of pH values (10 < pH < 11) where adsorption may be used as a method of doping 3Y-TZP with Cu[sup 2+]. The maximum mole percent of the CuO additions is determined by the specific surface area of the 3Y-TZP powder; a powder with a specific surface area of 16.1 m[sup 2]/g is limited to about 1 mol% CuO. Compacts made from powders doped with CuO using this method exhibited an enhancement in superplasticity comparable to that observed in other studiesmore » using samples doped with CuO by attrition milling.« less

Colour centre recovery in yttria-stabilised zirconia: photo-induced versus thermal processes

NASA Astrophysics Data System (ADS)

Costantini, Jean-Marc; Touati, Nadia; Binet, Laurent; Lelong, Gérald; Guillaumet, Maxime; Beuneu, François

2018-05-01

The photo-annealing of colour centres in yttria-stabilised zirconia (YSZ) was studied by electron paramagnetic resonance spectroscopy upon UV-ray or laser light illumination, and compared to thermal annealing. Stable hole centres (HCs) were produced in as-grown YSZ single crystals by UV-ray irradiation at room temperature (RT). The HCs produced by 200-MeV Au ion irradiation, as well as the F+-type centres (? centres involving oxygen vacancies) were left unchanged upon UV illumination. In contrast, a significant photo-annealing of the latter point defects was achieved in 1.4-MeV electron-irradiated YSZ by 553-nm laser light irradiation at RT. Almost complete photo-bleaching was achieved by laser irradiation inside the absorption band of ? centres centred at a wavelength 550 nm. Thermal annealing of these colour centres was also followed by UV-visible absorption spectroscopy showing full bleaching at 523 K. Colour-centre evolutions by photo-induced and thermally activated processes are discussed on the basis of charge exchange processes between point defects.

Reactions of yttria-stabilized zirconia with oxides and sulfates of various elements

NASA Technical Reports Server (NTRS)

Zaplatynsky, I.

1978-01-01

The reactions between partially stabilized zirconia, containing 8 weight-percent yttria, and oxides and sulfates of various elements were studied at 1200, 1300, and 1400 C for times to 800, 400, and 200 hours, respectively. These oxides and sulfates represent impurities and additives potentially present in gas turbine fuels or impurities in the turbine combustion air as well as the elements of the substrate alloys in contact with zirconia. Based on the results, these compounds can be classified in four groups: (1) compounds which did not react with zirconia (Na2SO4, K2SO4, Cr2O3, Al2O3 and NiO); (2) compounds that reached completely with both zirconia phases (CaO, BaO, and BaSO4); (3) compounds that reacted preferentially with monoclinic zirconia (Na2O, K2O, CoO, Fe2O3, MgO, SiO2, and ZnO); and (4) compounds that reacted preferentially with cubic zirconia (V2O5, P2O5).

Artificial in-plane ordering of textured YBa2Cu3O(7-x) films deposited on polycrystalline yttria-stabilized zirconia substrates

NASA Astrophysics Data System (ADS)

Harshavardhan, K. S.; Rajeswari, M.; Hwang, D. M.; Chen, C. Y.; Sands, T. D.; Venkatesan, T.; Tkaczyk, J. E.; Lay, K. W.; Safari, A.; Johnson, L.

1992-12-01

Anisotropic surface texturing of the polycrystalline yttria-stabilized zirconia substrates, prior to YBa2Cu3O(7-x) film deposition, is shown to promote in-plane (basal plane) ordering of the film growth in addition to the c-axis texturing. The Jc's of the films in the weak-link-dominated low-field regime are enhanced considerably, and this result is attributed to the reduction of weak links resulting from a reduction in the number of in-plane large-angle grain boundaries.

Effect of environmental dust particles on laser textured yttria-stabilized zirconia surface in humid air ambient

NASA Astrophysics Data System (ADS)

Yilbas, B. S.; Ali, H.; Al-Sharafi, A.; Al-Sulaiman, F.; Karatas, C.

2018-05-01

Zirconium nitride is used as a selective surface for concentrated solar heating applications and one of the methods to form a zirconium nitride is texturing of zirconia surface by a high intensity laser beam under high pressure nitrogen gas environment. Laser texturing also provides hydrophobic surface characteristics via forming micro/nano pillars at the surface; however, environmental dust settlement on textured surface influences the surface characteristics significantly. In the present study, laser texturing of zirconia surface and effects of the dust particles on the textured surface in a humid air ambient are investigated. Analytical tools are used to assess the morphological changes on the laser textured surface prior and after the dust settlement in the humid air ambient. It is found that laser textured surface has hydrophobic characteristics. The mud formed during condensate of water on the dust particles alters the characteristics of the laser textured surface. The tangential force required to remove the dry mud from the textured surface remains high; in which case, the dried liquid solution at the mud-textured surface interface is responsible for the strong adhesion of the dry mud on the textured surface. The textured surface becomes hydrophilic after the dry mud was removed from the surface by a desalinated water jet.

Particle and surfactant interactions effected polar and dispersive components of interfacial energy in nanocolloids

NASA Astrophysics Data System (ADS)

Harikrishnan, A. R.; Das, Sarit K.; Agnihotri, Prabhat K.; Dhar, Purbarun

2017-08-01

We segregate and report experimentally for the first time the polar and dispersive interfacial energy components of complex nanocolloidal dispersions. In the present study, we introduce a novel inverse protocol for the classical Owens Wendt method to determine the constitutive polar and dispersive elements of surface tension in such multicomponent fluidic systems. The effect of nanoparticles alone and aqueous surfactants alone are studied independently to understand the role of the concentration of the dispersed phase in modulating the constitutive elements of surface energy in fluids. Surfactants are capable of altering the polar component, and the combined particle and surfactant nanodispersions are shown to be effective in modulating the polar and dispersive components of surface tension depending on the relative particle and surfactant concentrations as well as the morphological and electrostatic nature of the dispersed phases. We observe that the combined surfactant and particle colloid exhibits a similar behavior to that of the particle only case; however, the amount of modulation of the polar and dispersive constituents is found to be different from the particle alone case which brings to the forefront the mechanisms through which surfactants modulate interfacial energies in complex fluids. Accordingly, we are able to show that the observations can be merged into a form of quasi-universal trend in the trends of polar and dispersive components in spite of the non-universal character in the wetting behavior of the fluids. We analyze the different factors affecting the polar and dispersive interactions in such complex colloids, and the physics behind such complex interactions has been explained by appealing to the classical dispersion theories by London, Debye, and Keesom as well as by Derjaguin-Landau-Verwey-Overbeek theory. The findings shed light on the nature of wetting behavior of such complex fluids and help in predicting the wettability and the degree of

Relation Between the Arc-Root Fluctuations, the Cold Boundary Layer Thickness and the Particle Thermal Treatment

NASA Astrophysics Data System (ADS)

Noguès, E.; Fauchais, P.; Vardelle, M.; Granger, P.

2007-12-01

In plasma spraying, the arc-root fluctuations, modifying the length and characteristics of the plasma jet, have an important influence on particle thermal treatment. These voltage fluctuations are strongly linked to the thickness of the cold boundary layer (CBL), surrounding the arc column. This thickness depends on the plasma spray parameters (composition and plasma forming gas mass flow rate, arc current, etc.) and the plasma torch design (anode-nozzle internal diameter and shape, etc.). In order to determine the influence of these different spray parameters on the CBL properties and voltage fluctuations, experiments were performed with two different plasma torches from Sulzer Metco. The first one is a PTF4 torch with a cylindrical anode-nozzle, working with Ar-H2 plasma gas mixtures and the second one is a 3MB torch with either a conical or a cylindrical anode-nozzle, working with N2-H2 plasma gas mixtures. Moreover, arc voltage fluctuations influence on particle thermal treatment was studied through the measurements of transient temperature and velocity of particles, issued from an yttria partially stabilized zirconia powder with a size distribution between 5 and 25 μm.

The nano-particle dispersion strengthening of V-4Cr-4Ti alloys for high temperature application in fusion reactors

NASA Astrophysics Data System (ADS)

Zheng, Pengfei; Chen, Jiming; Xu, Zengyu; Duan, Xuru

2013-10-01

V-4Cr-4Ti was identified as an attractive structural material for Li blanket in fusion reactors. However, both high temperature and irradiation induced degradation are great challenges for this material. It was thought that the nano-particles with high thermal stability can efficiently strengthen the alloy at elevated temperatures, and accommodate the irradiation induced defects at the boundaries. This study is a starting work aiming at improving the creep resistance and reducing the irradiation induced degradation for V-4Cr-4Ti alloy. Currently, we focus on the preparation of some comparative nano-particle dispersion strengthened V-4Cr-4Ti alloys. A mechanical alloying (MA) route is used to fabricate yttrium and carbides added V-4Cr-4Ti alloys. Nano-scale yttria, carbides and other possible particles have a combined dispersion-strengthening effect on the matrices of these MA-fabricated V-4Cr-4Ti alloys. High-temperature annealing is carried out to stabilize the optimized nano-particles. Mechanical properties are tested. Microstructures of the MA-fabricated V-4Cr-4Ti alloys with yttrium and carbide additions are characterized. Based on these results, the thermal stability of different nano-particle agents are classified. ITER related China domestic project 2011GB108007.

Atomic structure and composition of the yttria-stabilized zirconia (111) surface.

PubMed

Vonk, Vedran; Khorshidi, Navid; Stierle, Andreas; Dosch, Helmut

2013-06-01

Anomalous and nonanomalous surface X-ray diffraction is used to investigate the atomic structure and composition of the yttria-stabilized zirconia (YSZ)(111) surface. By simulation it is shown that the method is sensitive to Y surface segregation, but that the data must contain high enough Fourier components in order to distinguish between different models describing Y/Zr disorder. Data were collected at room temperature after two different annealing procedures. First by applying oxidative conditions at 10 - 5  mbar O 2 and 700 K to the as-received samples, where we find that about 30% of the surface is covered by oxide islands, which are depleted in Y as compared with the bulk. After annealing in ultrahigh vacuum at 1270 K the island morphology of the surface remains unchanged but the islands and the first near surface layer get significantly enriched in Y. Furthermore, the observation of Zr and oxygen vacancies implies the formation of a porous surface region. Our findings have important implications for the use of YSZ as solid oxide fuel cell electrode material where yttrium atoms and zirconium vacancies can act as reactive centers, as well as for the use of YSZ as substrate material for thin film and nanoparticle growth where defects control the nucleation process.

Atomistic modeling of La3+ doping segregation effect on nanocrystalline yttria-stabilized zirconia.

PubMed

Zhang, Shenli; Sha, Haoyan; Castro, Ricardo H R; Faller, Roland

2018-05-16

The effect of La3+ doping on the structure and ionic conductivity change in nanocrystalline yttria-stabilized zirconia (YSZ) was studied using a combination of Monte Carlo and molecular dynamics simulations. The simulation revealed the segregation of La3+ at eight tilt grain boundary (GB) structures and predicted an average grain boundary (GB) energy decrease of 0.25 J m-2, which is close to the experimental values reported in the literature. Cation stabilization was found to be the main reason for the GB energy decrease, and energy fluctuations near the grain boundary are smoothed out with La3+ segregation. Both dynamic and energetic analysis on the Σ13(510)/[001] GB structure revealed La3+ doping hinders O2- diffusion in the GB region, where the diffusion coefficient monotonically decreases with increasing La3+ doping concentration. The effect was attributed to the increase in the site-dependent migration barriers for O2- hopping caused by segregated La3+, which also leads to anisotropic diffusion at the GB.

Ageing and thermal recovery of paramagnetic centers induced by electron irradiation in yttria-stabilized zirconia

NASA Astrophysics Data System (ADS)

Costantini, J. M.; Beuneu, F.

We have used electron spin resonance spectroscopy to study the defects induced in yttria-stabilized zirconia (YSZ) single crystals by 2.5-MeV electron irradiations. Two paramagnetic centers are produced: the first one with an axial <111> symmetry is similar to the trigonal Zr3+ electron center (T center) found after X-ray irradiation or thermo-chemical reduction, whereas the second one is a new oxygen hole center with an axial <100> symmetry different from the orthorhombic O- center induced by X-ray irradiation. At a fluence around 10(18) e/cm(2) , both centers are bleached out near 600 K, like the corresponding X-ray induced defects. At a fluence around 10(19) e/cm(2) , defects are much more stable, since complete thermal bleaching occurs near 1000 K. Accordingly, ageing of as-irradiated samples shows that high-dose defects at more stable than the low-dose ones.

Orientation-dependent hydration structures at yttria-stabilized cubic zirconia surfaces

DOE PAGES

Hou, Binyang; Kim, Seunghyun; Kim, Taeho; ...

2016-11-30

Water interaction with surfaces is very important and plays key roles in many natural and technological processes. Because the experimental challenges that arise when studying the interaction water with specific crystalline surfaces, most studies on metal oxides have focused on powder samples, which averaged the interaction over different crystalline surfaces. As a result, studies on the crystal orientation-dependent interaction of water with metal oxides are rarely available in the literature. In this work, water adsorption at 8 mol % yttria-stabilized cubic single crystal zirconia (100) and (111) surfaces was studied in terms of interfacial hydration structures using high resolution X-raymore » reflectivity measurements. The interfacial electron density profiles derived from the structure factor analysis of the measured data show the existence of multiple layers of adsorbed water with additional peculiar metal adsorption near the oxide surfaces.Surface relaxation, depletion, and interaction between the adsorbed layers and bulk water are found to vary greatly between the two surfaces and are also different when compared to the previously studied (110) surface. The fractional ratio between chemisorbed and physisorbed water species were also quantitatively estimated, which turned out to vary dramatically from surface to surface. Finally, the result gives us a unique opportunity to reconsider the simplified 2:1 relation between chemisorption and physisorption, originally proposed by Morimoto et al. based on the adsorption isotherms of water on powder metal oxide samples.« less

Brazing of Stainless Steel to Yttria-Stabilized Zirconia Using Gold-Based Brazes for Solid Oxide Fuel Cell Applications

NASA Technical Reports Server (NTRS)

Singh, M.; Shpargel, T. P.; Asthana, R.

2007-01-01

Two gold-base active metal brazes (gold-ABA and gold-ABA-V) were evaluated for oxidation resistance to 850 C, and used to join yttria-stabilized zirconia (YSZ) to a corrosion-resistant ferritic stainless steel for possible use in solid oxide fuel cells. Thermogravimetric analysis and optical microscopy and scanning electron microscopy coupled with energy-dispersive spectroscopy were used to evaluate the braze oxidation behavior, and microstructure and composition of the YSZ/braze/steel joints. Both gold-ABA and gold-ABA-V exhibited nearly linear oxidation kinetics at 850 C, with gold-ABA-V showing faster oxidation than gold-ABA. Both brazes produced metallurgically sound YSZ/steel joints due to chemical interactions of Ti and V with the YSZ and steel substrates.

Cerium reduction at the interface between ceria and yttria-stabilised zirconia and implications for interfacial oxygen non-stoichiometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Kepeng; Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, 110016 Shenyang; Schmid, Herbert

2014-03-01

Epitaxial CeO{sub 2} films with different thickness were grown on Y{sub 2}O{sub 3} stabilised Zirconia substrates. Reduction of cerium ions at the interface between CeO{sub 2} films and yttria stabilised zirconia substrates is demonstrated using aberration-corrected scanning transmission electron microscopy combined with electron energy-loss spectroscopy. It is revealed that most of the Ce ions were reduced from Ce{sup 4+} to Ce{sup 3+} at the interface region with a decay of several nanometers. Several possibilities of charge compensations are discussed. Irrespective of the details, such local non-stoichiometries are crucial not only for understanding charge transport in such hetero-structures but also formore » understanding ceria catalytic properties.« less

Effects of sputtering mode on the microstructure and ionic conductivity of yttria-stabilized zirconia films

NASA Astrophysics Data System (ADS)

Yeh, Tsung-Her; Lin, Ruei-De; Cherng, Bo-Ruei; Cherng, Jyh-Shiarn

2018-05-01

The microstructure and ionic conductivity of reactively sputtered yttria-stabilized zirconia (YSZ) films are systematically studied. Those films were reactively sputtered in various sputtering modes using a closed-loop controlled system with plasma emission monitoring. A transition-mode sputtering corresponding to 45% of target poisoning produces a microstructure with ultrafine crystallites embedded in an amorphous matrix, which undergoes an abnormal grain growth upon annealing at 800 °C. At 500 °C, the measured ionic conductivity of this annealed film is higher, by about a half order of magnitude, than those of its poisoned-mode counterparts, which are in turn significantly higher than that of the YSZ bulk by about two orders of magnitude. The abnormally-grown ultra-large grain size of the film deposited in the transition mode and then annealed is believed to be responsible for the former comparison due to the suppression of the grain boundary blocking effect, while the latter comparison can be attributed to the interface effect.

High-quality crystalline yttria-stabilized-zirconia thin layer for photonic applications

NASA Astrophysics Data System (ADS)

Marcaud, Guillaume; Matzen, Sylvia; Alonso-Ramos, Carlos; Le Roux, Xavier; Berciano, Mathias; Maroutian, Thomas; Agnus, Guillaume; Aubert, Pascal; Largeau, Ludovic; Pillard, Valérie; Serna, Samuel; Benedikovic, Daniel; Pendenque, Christopher; Cassan, Eric; Marris-Morini, Delphine; Lecoeur, Philippe; Vivien, Laurent

2018-03-01

Functional oxides are considered as promising materials for photonic applications due to their extraordinary and various optical properties. Especially, yttria-stabilized zirconia (YSZ) has a high refractive index (˜2.15), leading to a good confinement of the optical mode in waveguides. Furthermore, YSZ can also be used as a buffer layer to expand toward a large family of oxides-based thin-films heterostructures. In this paper, we report a complete study of the structural properties of YSZ for the development of integrated optical devices on sapphire in telecom wavelength range. The substrate preparation and the epitaxial growth using pulsed-laser deposition technique have been studied and optimized. High-quality YSZ thin films with remarkably sharp x-ray diffraction rocking curve peaks in 10-3∘ range have then been grown on sapphire (0001). It was demonstrated that a thermal annealing of sapphire substrate before the YSZ growth allowed controlling the out-of-plane orientation of the YSZ thin film. Single-mode waveguides were finally designed, fabricated, and characterized for two different main orientations of high-quality YSZ (001) and (111). Propagation loss as low as 2 dB/cm at a wavelength of 1380 nm has been demonstrated for both orientations. These results pave the way for the development of a functional oxides-based photonics platform for numerous applications including on-chip optical communications and sensing.

Brazing of Stainless Steels to Yttria Stabilized Zirconia (YSZ) for Solid Oxide Fuel Cells

NASA Technical Reports Server (NTRS)

Shpargel, Tarah P.; Needham, Robert J.; Singh, M.; Kung, Steven C.

2005-01-01

Recently, there has been a great deal of interest in research, development, and commercialization of solid oxide fuel cells. Joining and sealing are critical issues that will need to be addressed before SOFC's can truly perform as expected. Ceramics and metals can be difficult to join together, especially when the joint must withstand up to 900 C operating temperature of the SOFC's. The goal of the present study is to find the most suitable braze material for joining of yttria stabilized zirconia (YSZ) to stainless steels. A number of commercially available braze materials TiCuSil, TiCuNi, Copper-ABA, Gold-ABA, and Gold-ABA-V have been evaluated. The oxidation behavior of the braze materials and steel substrates in air was also examined through thermogravimetric analysis. The microstructure and composition of the brazed regions have been examined by optical and scanning electron microscopy and EDS analysis. Effect of braze composition and processing conditions on the interfacial microstructure and composition of the joint regions will be presented.

Investigation of magneto-optical properties of ferrofluids by laser light scattering techniques

NASA Astrophysics Data System (ADS)

Nepomnyashchaya, E. K.; Prokofiev, A. V.; Velichko, E. N.; Pleshakov, I. V.; Kuzmin, Yu I.

2017-06-01

Investigation of magnetooptical characteristics of ferrofluids is an important task aimed at the development of novel optoelectronic systems. This article reports on the results obtained in the experimental studies of the factors that affect the intensity and spatial distribution of the laser radiation scattered by magnetic particles and their agglomerates in a magnetic field. Laser correlation spectroscopy and direct measurements of laser radiation scattering for studies of the interactions and magnetooptical properties of magnetic particles in solutions were employed. The objects were samples of nanodispersed magnetite (Fe3O4) suspended in kerosene and in water. Our studies revealed some new behavior of magnetic particles in external magnetic and light fields, which make ferrofluids promising candidates for optical devices.

Initial Bacterial Adhesion on Different Yttria-Stabilized Tetragonal Zirconia Implant Surfaces in Vitro

PubMed Central

Karygianni, Lamprini; Jähnig, Andrea; Schienle, Stefanie; Bernsmann, Falk; Adolfsson, Erik; Kohal, Ralf J.; Chevalier, Jérôme; Hellwig, Elmar; Al-Ahmad, Ali

2013-01-01

Bacterial adhesion to implant biomaterials constitutes a virulence factor leading to biofilm formation, infection and treatment failure. The aim of this study was to examine the initial bacterial adhesion on different implant materials in vitro. Four implant biomaterials were incubated with Enterococcus faecalis, Staphylococcus aureus and Candida albicans for 2 h: 3 mol % yttria-stabilized tetragonal zirconia polycrystal surface (B1a), B1a with zirconium oxide (ZrO2) coating (B2a), B1a with zirconia-based composite coating (B1b) and B1a with zirconia-based composite and ZrO2 coatings (B2b). Bovine enamel slabs (BES) served as control. The adherent microorganisms were quantified and visualized using scanning electron microscopy (SEM); DAPI and live/dead staining. The lowest bacterial count of E. faecalis was detected on BES and the highest on B1a. The fewest vital C. albicans strains (42.22%) were detected on B2a surfaces, while most E. faecalis and S. aureus strains (approximately 80%) were vital overall. Compared to BES; coated and uncoated zirconia substrata exhibited no anti-adhesive properties. Further improvement of the material surface characteristics is essential. PMID:28788415

Initial Bacterial Adhesion on Different Yttria-Stabilized Tetragonal Zirconia Implant Surfaces in Vitro.

PubMed

Karygianni, Lamprini; Jähnig, Andrea; Schienle, Stefanie; Bernsmann, Falk; Adolfsson, Erik; Kohal, Ralf J; Chevalier, Jérôme; Hellwig, Elmar; Al-Ahmad, Ali

2013-12-04

Bacterial adhesion to implant biomaterials constitutes a virulence factor leading to biofilm formation, infection and treatment failure. The aim of this study was to examine the initial bacterial adhesion on different implant materials in vitro . Four implant biomaterials were incubated with Enterococcus faecalis , Staphylococcus aureus and Candida albicans for 2 h: 3 mol % yttria-stabilized tetragonal zirconia polycrystal surface (B1a), B1a with zirconium oxide (ZrO₂) coating (B2a), B1a with zirconia-based composite coating (B1b) and B1a with zirconia-based composite and ZrO₂ coatings (B2b). Bovine enamel slabs (BES) served as control. The adherent microorganisms were quantified and visualized using scanning electron microscopy (SEM); DAPI and live/dead staining. The lowest bacterial count of E. faecalis was detected on BES and the highest on B1a. The fewest vital C. albicans strains (42.22%) were detected on B2a surfaces, while most E. faecalis and S. aureus strains (approximately 80%) were vital overall. Compared to BES; coated and uncoated zirconia substrata exhibited no anti-adhesive properties. Further improvement of the material surface characteristics is essential.

Color center annealing and ageing in electron and ion-irradiated yttria-stabilized zirconia

NASA Astrophysics Data System (ADS)

Costantini, Jean-Marc; Beuneu, François

2005-04-01

We have used X-band electron paramagnetic resonance (EPR) measurements at room-temperature (RT) to study the thermal annealing and RT ageing of color centers induced in yttria-stabilized zirconia (YSZ), i.e. ZrO2:Y with 9.5 mol% Y2O3, by swift electron and ion-irradiations. YSZ single crystals with the <1 0 0> orientation were irradiated with 2.5 MeV electrons, and implanted with 100 MeV 13C ions. Electron and ion beams produce the same two color centers, namely an F+-type center (singly ionized oxygen vacancy) and the so-called T-center (Zr3+ in a trigonal oxygen local environment) which is also produced by X-ray irradiations. Isochronal annealing was performed in air up to 973 K. For both electron and ion irradiations, the defect densities are plotted versus temperature or time at various fluences. The influence of a thermal treatment at 1373 K of the YSZ single crystals under vacuum prior to the irradiations was also investigated. In these reduced samples, color centers are found to be more stable than in as-received samples. Two kinds of recovery processes are observed depending on fluence and heat treatment.

Recent Progress in the Development of Neodymium Doped Ceramic Yttria

NASA Technical Reports Server (NTRS)

Prasad, Narasimha S.; Edwards, Chris; Trivedi, Sudhir B.; Kutcher, Susan; Wang, Chen-Chia; Kim, Joo-Soo; Hommerich, Uwe; Shukla, Vijay; Sadangi, Rajendra; Kear, Bernard

2007-01-01

Solid-state lasers play a significant role in providing the technology necessary for active remote sensing of the atmosphere. Neodymium doped yttria (Nd:Y2O3) is considered to be an attractive material due to its possible lasing wavelengths of aprrox.914 nm and approx.946 nm for ozone profiling. These wavelengths when frequency tripled can generate UV light at approx.305 nm and approx.315 nm, which is particularly useful for ozone sensing using differential absorption lidar technique. For practical realization of space based UV transmitter technology, ceramic Nd:Y2O3 material is considered to possess great potential. A plasma melting and quenching method has been developed to produce Nd3+ doped powders for consolidation into Nd:Y2O3 ceramic laser materials. This far-from-equilibrium processing methodology allows higher levels of rare earth doping than can be achieved by equilibrium methods. The method comprises of two main steps: (a) plasma melting and quenching to generate dense, and homogeneous doped metastable powders, (b) pressure assisted consolidation of these powders by hot isostatic pressing to make dense nanocomposite ceramics. Using this process, several 1" x 1" ceramic cylinders have been produced. The infrared transmission of undoped Y2O3 ceramics was as high as approx.75% without anti-reflection coating. In the case of Nd:Y2O3 ceramics infrared transmission values of approx.50% were achieved. Furthermore, Nd:Y2O3 samples with dopant concentrations of up to approx.2 at. % were prepared without significant emission quenching.

Characterization of Y-Ba-Cu-O thin films and yttria-stabilized zirconia intermediate layers on metal alloys grown by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Reade, R. P.; Mao, X. L.; Russo, R. E.

1991-08-01

The use of an intermediate layer is necessary for the growth of YBaCuO thin films on polycrystalline metallic alloys for tape conductor applications. A pulsed laser deposition process to grow controlled-orientation yttria-stabilized zirconia (YSZ) films as intermediate layers on Haynes Alloy No. 230 was developed and characterized. YBaCuO films deposited on these YSZ-coated substrates are primarily c-axis oriented and superconducting as deposited. The best YBaCuO films grow on (001)-oriented YSZ intermediate layers and have Tc (R = 0) = 86.0 K and Jc about 3000 A/sq cm at 77 K.

The Evolution of Solid Oxide Fuel Cell Nickel-Yttria Stabilized Zirconia Anodes Studied Using Electrochemical and Three-Dimensional Microstructural Characterizations

NASA Astrophysics Data System (ADS)

Kennouche, David O.

This thesis focuses on Solid Oxide Fuel Cells (SOFCs). The 21st century will see major changes in the way energy is produced, stored, and used around the world. SOFCs, which provide an efficient, scalable, and low-pollution alternative method for electricity generation, are expected to play an important role. SOFCs can also be operated in electrolysis mode for energy storage, important since health and economic reasons are causing a shift towards intermittent renewable energy resources. However, multiple limitations mainly linked to cost and durability have prevented the expansion of this technology to mass markets. This work focuses on the Nickel - Yttria Stabilized Zirconia (Ni-YSZ) anode that is widely used in SOFCs. Coarsening of Ni in the Ni-YSZ anode has been widely cited as a primary cause of long-term SOFC degradation. While there have been numerous studies of Ni coarsening reported, these have typically only tracked the evolution of Ni particle size, not the entire microstructure, and have typically not been correlated directly with electrochemical performance. In this thesis, the advanced tomography techniques Focused Ion Beam - Scanning Electron Microscopy (FIB-SEM) tomography and Trans- mission X-ray Microscopy (TXM) have been utilized to enable insight into the evolution of Ni-YSZ structure and how it relates to performance degradation. Extensive anode aging studies were done for relatively short times using temperatures higher than in normal SOFC operation in order to accelerate microstructural evolution. In addition the microstructure changes were correlated with changes in anode polarization resistance. While most of the measurements were done by comparing different anodes aged under different conditions, the first example of a "pseudo in situ" measurement where the same anode was 3D imaged repeatedly with intervening aging steps, was also demonstrated. A microstructural evolution model that focuses on the active three-phase boundary density was

Laser surface modification of Yttria Stabilized Zirconia (YSZ) thermal barrier coating on AISI H13 tool steel substrate

NASA Astrophysics Data System (ADS)

Reza, M. S.; Aqida, S. N.; Ismail, I.

2018-03-01

This paper presents laser surface modification of plasma sprayed yttria stabilized zirconia (YSZ) coating to seal porosity defect. Laser surface modification on plasma sprayed YSZ was conducted using 300W JK300HPS Nd: YAG laser at different operating parameters. Parameters varied were laser power and pulse frequency with constant residence time. The coating thickness was measured using IM7000 inverted optical microscope and surface roughness was analysed using two-dimensional Mitutoyo Surface Roughness Tester. Surface roughness of laser surface modification of YSZ H-13 tool steel decreased significantly with increasing laser power and decreasing pulse frequency. The re-melted YSZ coating showed higher hardness properties compared to as-sprayed coating surface. These findings were significant to enhance thermal barrier coating surface integrity for dies in semi-solid processing.

Straight-chain halocarbon forming fluids for TRISO fuel kernel production - Tests with yttria-stabilized zirconia microspheres

NASA Astrophysics Data System (ADS)

Baker, M. P.; King, J. C.; Gorman, B. P.; Braley, J. C.

2015-03-01

Current methods of TRISO fuel kernel production in the United States use a sol-gel process with trichloroethylene (TCE) as the forming fluid. After contact with radioactive materials, the spent TCE becomes a mixed hazardous waste, and high costs are associated with its recycling or disposal. Reducing or eliminating this mixed waste stream would not only benefit the environment, but would also enhance the economics of kernel production. Previous research yielded three candidates for testing as alternatives to TCE: 1-bromotetradecane, 1-chlorooctadecane, and 1-iodododecane. This study considers the production of yttria-stabilized zirconia (YSZ) kernels in silicone oil and the three chosen alternative formation fluids, with subsequent characterization of the produced kernels and used forming fluid. Kernels formed in silicone oil and bromotetradecane were comparable to those produced by previous kernel production efforts, while those produced in chlorooctadecane and iodododecane experienced gelation issues leading to poor kernel formation and geometry.

Morphology and electronic structure of nanoscale powders of calcium hydroxyapatite

NASA Astrophysics Data System (ADS)

Kurgan, Nataly; Karbivskyy, Volodymyr; Kasyanenko, Vasyl

2015-02-01

Atomic force microscopy, infrared spectroscopy and NMR studied morphological and physicochemical properties of calcium hydroxyapatite powders produced by changing the temperature parameters of synthesis. Features of morphology formation of calcium hydroxyapatite nanoparticles with an annealing temperature within 200°C to 1,100°C were determined. It is shown that the particle size of the apatite obtained that annealed 700°C is 40 nm corresponding to the particle size of apatite in native bone. The effect of dimension factor on structural parameters of calcium hydroxyapatite is manifested in a more local symmetry of the PO4 3- tetrahedra at nanodispersed calcium hydroxyapatite.

Ionic conductivity and thermal stability of magnetron-sputtered nanocrystalline yttria-stabilized zirconia

NASA Astrophysics Data System (ADS)

Sillassen, M.; Eklund, P.; Sridharan, M.; Pryds, N.; Bonanos, N.; Bøttiger, J.

2009-05-01

Thermally stable, stoichiometric, cubic yttria-stabilized zirconia (YSZ) thin-film electrolytes have been synthesized by reactive pulsed dc magnetron sputtering from a Zr-Y (80/20 at. %) alloy target. Films deposited at floating potential had a ⟨111⟩ texture. Single-line profile analysis of the 111 x-ray diffraction peak yielded a grain size of ˜20 nm and a microstrain of ˜2% regardless of deposition temperature. Films deposited at 400 °C and selected bias voltages in the range from -70 to -200 V showed a reduced grain size for higher bias voltages, yielding a grain size of ˜6 nm and a microstrain of ˜2.5% at bias voltages of -175 and -200 V with additional incorporation of argon. The films were thermally stable; very limited grain coarsening was observed up to an annealing temperature of 800 °C. Temperature-dependent impedance spectroscopy analysis of the YSZ films with Ag electrodes showed that the in-plane ionic conductivity was within one order of magnitude higher in films deposited with substrate bias corresponding to a decrease in grain size compared to films deposited at floating potential. This suggests that there is a significant contribution to the ionic conductivity from grain boundaries. The activation energy for oxygen ion migration was determined to be between 1.14 and 1.30 eV.

Surface modification of yttria stabilized zirconia via polydopamine inspired coating for hydroxyapatite biomineralization

NASA Astrophysics Data System (ADS)

Zain, Norhidayu Muhamad; Hussain, Rafaqat; Kadir, Mohammed Rafiq Abdul

2014-12-01

Yttria stabilized zirconia (YSZ) has been widely used as biomedical implant due to its high strength and enhanced toughening characteristics. However, YSZ is a bioinert material which constrains the formation of chemical bonds with bone tissue following implantation. Inspired by the property of mussels, the surface of YSZ ceramics was functionalized by quinone-rich polydopamine to facilitate the biomineralization of hydroxyapatite. YSZ discs were first immersed in 2 mg/mL of stirred or unstirred dopamine solution at either 25 or 37 °C. The samples were then incubated in 1.5 simulated body fluid (SBF) for 7d. The effect of coating temperature for stirred and unstirred dopamine solutions during substrate grafting was investigated on the basis of chemical compositions, wettability and biomineralization of hydroxyapatite on the YSZ functionalized surface. The results revealed that the YSZ substrate grafted at 37 °C in stirred solution of dopamine possessed significantly improved hydrophilicity (water contact angle of 44.0 ± 2.3) and apatite-mineralization ability (apatite ratio of 1.78). In summary, the coating temperature and stirring condition during grafting procedure affected the chemical compositions of the films and thus influenced the formation of apatite layer on the substrate during the biomineralization process.

Effects of yttrium, aluminum, and chromium concentrations in bond coatings on the performance of zirconia-yttria thermal barriers

NASA Technical Reports Server (NTRS)

Stecura, S.

1979-01-01

A cyclic furnace study was conducted between 990 - 280 C and 1095 - 280 C to evaluate the effects of yttrium, chromium, and aluminum concentrations in nickel base alloy bond coatings and also the effect of the bond coating thickness on the performance of yttria-stabilized zirconia thermal barrier coatings. The presence and the concentration of yttrium is very critical. Without yttrium, rapid oxidation of Ni-Al, Ni-Cr, and Ni-Cr-Al bond coatings causes zirconia thermal barrier coatings to fail very rapidly. Concentrations of chrominum and aluminum in Ni-Cr-Al-Y bond coating have a very significant effect on the thermal barrier coating life. This effect, however, is not as great as that due to yttrium. Furthermore, the thickness and the thickness uniformity also have a very significant effect on the life of the thermal barrier system.

Dominant pinning mechanisms in YBa2Cu3O7-x films on single and polycrystalline yttria stabilized zirconia substrates

NASA Astrophysics Data System (ADS)

Harshavardhan, K. S.; Rajeswari, M.; Hwang, D. M.; Chen, C. Y.; Sands, T.; Venkatesan, T.; Tkaczyk, J. E.; Lay, K. W.; Safari, A.

1992-04-01

Critical-current densities have been measured in YBa2Cu3O7-x films deposited on (100) yttria stabilized zirconia (YSZ) and polycrystalline YSZ substrates as a function of temperature (4.5-88 K), magnetic field (0-1 T) and orientation relative to the applied field. The results indicate that in films on polycrystalline substrates, surface and interface pinning play a dominant role at high temperatures. In films on (100) YSZ, pinning is mainly due to intrinsic layer pinning as well as extrinsic pinning associated with the interaction of the fluxoids with point defects and low energy planar (2D) boundaries. The differences are attributed to the intrinsic rigidity of single fluxoids which is reduced in films on polycrystalline substrates thereby weakening the intrinsic layer pinning.

Nearly full-dense and fine-grained AZO:Y ceramics sintered from the corresponding nanoparticles

PubMed Central

2012-01-01

Aluminum-doped zinc oxide ceramics with yttria doping (AZO:Y) ranging from 0 to 0.2 wt.% were fabricated by pressureless sintering yttria-modified nanoparticles in air at 1,300°C. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, a physical property measurement system, and a densimeter were employed to characterize the precursor nanoparticles and the sintered AZO ceramics. It was shown that a small amount of yttria doping can remarkably retard the growth of the as-received precursor nanoparticles, further improve the microstructure, refine the grain size, and enhance the density for the sintered ceramic. Increasing the yttria doping to 0.2 wt.%, the AZO:Y nanoparticles synthetized by a coprecipitation process have a nearly sphere-shaped morphology and a mean particle diameter of 15.1 nm. Using the same amount of yttria, a fully dense AZO ceramic (99.98% of theoretical density) with a grain size of 2.2 μm and a bulk resistivity of 4.6 × 10−3 Ω·cm can be achieved. This kind of AZO:Y ceramic has a potential to be used as a high-quality sputtering target to deposit ZnO-based transparent conductive films with better optical and electrical properties. PMID:22929049

Synthesis and Characterization of Yttria-Stabilized Zirconia Nanoparticles Doped with Ytterbium and Gadolinium: ZrO2 9.5Y2O3 5.6Yb2O3 5.2Gd2O3

NASA Astrophysics Data System (ADS)

Bahamirian, M.; Hadavi, S. M. M.; Rahimipour, M. R.; Farvizi, M.; Keyvani, A.

2018-03-01

Defect cluster thermal barrier coatings (TBCs) are attractive alternatives to Yttria-stabilized zirconia (YSZ) in advanced applications. In this study, YSZ nanoparticles doped with ytterbium and gadolinium (ZrO2 9.5Y2O3 5.6Yb2O3 5.2Gd2O3 (ZGYbY)) were synthesized through a chemical co-precipitation and calcination method, and characterized by in situ high-temperature X-ray diffraction analysis in the temperature range of 25 °C to 1000 °C (HTK-XRD), thermogravimetric analysis, differential thermal analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, and field emission scanning electron microscopy (FE-SEM). Precise cell parameters of t-prime phase and the best zirconia phase for TBC applications were calculated by Cohen's and Rietveld refinement methods. Optimum crystallization temperature of the precursor powder was found to be 1000 °C. Furthermore, FE-SEM results for the calcined ZGYbY powders indicated orderly particles of uniform shape and size with a small tendency toward agglomeration. Average lattice thermal expansion coefficient in the temperature range of 25 °C to 1000 °C was determined to be 31.71 × 10-6 K-1.

Synthesis and Characterization of Yttria-Stabilized Zirconia Nanoparticles Doped with Ytterbium and Gadolinium: ZrO2 9.5Y2O3 5.6Yb2O3 5.2Gd2O3

NASA Astrophysics Data System (ADS)

Bahamirian, M.; Hadavi, S. M. M.; Rahimipour, M. R.; Farvizi, M.; Keyvani, A.

2018-06-01

Defect cluster thermal barrier coatings (TBCs) are attractive alternatives to Yttria-stabilized zirconia (YSZ) in advanced applications. In this study, YSZ nanoparticles doped with ytterbium and gadolinium (ZrO2 9.5Y2O3 5.6Yb2O3 5.2Gd2O3 (ZGYbY)) were synthesized through a chemical co-precipitation and calcination method, and characterized by in situ high-temperature X-ray diffraction analysis in the temperature range of 25 °C to 1000 °C (HTK-XRD), thermogravimetric analysis, differential thermal analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, and field emission scanning electron microscopy (FE-SEM). Precise cell parameters of t-prime phase and the best zirconia phase for TBC applications were calculated by Cohen's and Rietveld refinement methods. Optimum crystallization temperature of the precursor powder was found to be 1000 °C. Furthermore, FE-SEM results for the calcined ZGYbY powders indicated orderly particles of uniform shape and size with a small tendency toward agglomeration. Average lattice thermal expansion coefficient in the temperature range of 25 °C to 1000 °C was determined to be 31.71 × 10-6 K-1.

Influence of surface treatment of yttria-stabilized tetragonal zirconia polycrystal with hot isostatic pressing on cyclic fatigue strength.

PubMed

Iijima, Toshihiko; Homma, Shinya; Sekine, Hideshi; Sasaki, Hodaka; Yajima, Yasutomo; Yoshinari, Masao

2013-01-01

Hot isostatic pressing processed yttria-stabilized tetragonal zirconia polycrystal (HIP Y-TZP) has the potential for application to implants due to its high mechanical performance. The aim of this study was to investigate the influence of surface treatment of HIP Y-TZP on cyclic fatigue strength. HIP Y-TZP specimens were subjected to different surface treatments. Biaxial flexural strength was determined by both static and cyclic fatigue testing. In the cyclic fatigue test, the load was applied at a frequency of 10 Hz for 10(6) cycles in distilled water at 37°C. The surface morphology, roughness, and crystal phase of the surfaces were also evaluated. The cyclic fatigue strength (888 MPa) of HIP Y-TZP with sandblasting and acid-etching was more than twice that of Y-TZP as specified in ISO 13356 for surgical implants (320 MPa), indicating the clinical potential of this material.

Chromium doped nano-phase separated yttria-alumina-silica glass based optical fiber preform: fabrication and characterization

NASA Astrophysics Data System (ADS)

Dutta, Debjit; Dhar, Anirban; Das, Shyamal; Bysakh, Sandip; Kir'yanov, Alexandar; Paul, Mukul Chandra

2015-06-01

Transition metal (TM) doping in silica core optical fiber is one of the research area which has been studied for long time and Chromium (Cr) doping specially attracts a lot of research interest due to their broad emission band covering U, C and L band with many potential application such as saturable absorber or broadband amplifier etc. This paper present fabrication of Cr doped nano-phase separated silica fiber within yttria-alumina-silica core glass through conventional Modified Chemical Vapor Deposition (MCVD) process coupled with solution doping technique along with different material and optical characterization. For the first time scanning electron microscope (SEM) / energy dispersive X-ray (EDX) analysis of porous soot sample and final preform has been utilized to investigate incorporation mechanism of Crions with special emphasis on Cr-species evaporation at different stages of fabrication. We also report that optimized annealing condition of our fabricated preform exhibited enhanced fluorescence emission and a broad band within 550- 800 nm wavelength region under pumping at 532 nm wavelength due to nano-phase restructuration.

[Mechanical property of tooth-like yttria-stabilized tetragonal zirconia polycrystal by adding rare earth oxide].

PubMed

Gao, Yan; Zhang, Fuqiang; Gao, Jianhua

2012-02-01

To evaluate the influence of mechanical property of tooth-like yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) by adding rare earth oxide as colorants. Six kinds of tooth-like Y-TZP were made by introducing internal coloration technology. The colorants included rare earth oxide (Pr6O11, CeO2, Er2O3) and transition element oxide (MnO2). Mechanical properties (flexural strength, vickers hardness and fracture toughness) were tested. Microstructure was examined by scanning electron microscope(SEM), and the fracture model was analyzed. The range of flexural strength of the six kinds of tooth-like Y-TZP were (792 +/- 20)-(960 +/- 17) MPa, the fracture toughness were (4.72 +/- 0.31)-(5.64 +/- 0.38) MPam(1/2), and the vickers hardness were (1332 +/- 19)-(1380 +/- 17) MPa. SEM observation on the cross section of the six kinds of sintered composites showed a relatively dense polycrystal structure, and the fracture models was mixed type. Tooth-like Y-TZP is acquired with better mechanical properties (fracture toughness and vickers hardness) by adding rare earth oxide as colorants. It is available for clinical application.

Novel Cranial Implants of Yttria-Stabilized Zirconia as Acoustic Windows for Ultrasonic Brain Therapy.

PubMed

Gutierrez, Mario I; Penilla, Elias H; Leija, Lorenzo; Vera, Arturo; Garay, Javier E; Aguilar, Guillermo

2017-11-01

Therapeutic ultrasound can induce changes in tissues by means of thermal and nonthermal effects. It is proposed for treatment of some brain pathologies such as Alzheimer's, Parkinson's, Huntington's diseases, and cancer. However, cranium highly absorbs ultrasound reducing transmission efficiency. There are clinical applications of transcranial focused ultrasound and implantable ultrasound transducers proposed to address this problem. In this paper, biocompatible materials are proposed for replacing part of the cranium (cranial implants) based on low porosity polycrystalline 8 mol% yttria-stabilized-zirconia (8YSZ) ceramics as acoustic windows for brain therapy. In order to assess the viability of 8YSZ implants to effectively transmit ultrasound, various 8YSZ ceramics with different porosity are tested; their acoustic properties are measured; and the results are validated using finite element models simulating wave propagation to brain tissue through 8YSZ windows. The ultrasound attenuation is found to be linearly dependent on ceramics' porosity. Results for the nearly pore-free case indicate that 8YSZ is highly effective in transmitting ultrasound, with overall maximum transmission efficiency of ≈81%, compared to near total absorption of cranial bone. These results suggest that 8YSZ polycrystals could be suitable acoustic windows for ultrasound brain therapy at 1 MHz. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Micro-tubular solid oxide fuel cell based on a porous yttria-stabilized zirconia support

NASA Astrophysics Data System (ADS)

Panthi, Dhruba; Tsutsumi, Atsushi

2014-08-01

Solid oxide fuel cells (SOFCs) are promising electrochemical energy conversion devices owing to their high power generation efficiency and environmentally benign operation. Micro-tubular SOFCs, which have diameters ranging from a few millimeters to the sub-millimeter scale, offer several advantages over competing SOFCs such as high volumetric power density, good endurance against thermal cycling, and flexible sealing between fuel and oxidant streams. Herein, we successfully realized a novel micro-tubular SOFC design based on a porous yttria-stabilized zirconia (YSZ) support using multi-step dip coating and co-sintering methods. The micro-tubular SOFC consisted of Ni-YSZ, YSZ, and strontium-doped lanthanum manganite (LSM)-YSZ as the anode, electrolyte, and cathode, respectively. In addition, to facilitate current collection from the anode and cathode, Ni and LSM were applied as an anode current collector and cathode current collector, respectively. Micro-crystalline cellulose was selected as a pore former to achieve better shrinkage behavior of the YSZ support so that the electrolyte layer could be densified at a co-sintering temperature of 1300°C. The developed micro-tubular design showed a promising electrochemical performance with maximum power densities of 525, 442, and 354 mW cm-2 at 850, 800, and 750°C, respectively.

A critical assessment of in-flight particle state during plasma spraying of YSZ and its implications on coating properties and process reliability

NASA Astrophysics Data System (ADS)

Srinivasan, Vasudevan

Air plasma spray is inherently complex due to the deviation from equilibrium conditions, three dimensional nature, multitude of interrelated (controllable) parameters and (uncontrollable) variables involved, and stochastic variability at different stages. The resultant coatings are complex due to the layered high defect density microstructure. Despite the widespread use and commercial success for decades in earthmoving, automotive, aerospace and power generation industries, plasma spray has not been completely understood and prime reliance for critical applications such as thermal barrier coatings on gas turbines are yet to be accomplished. This dissertation is aimed at understanding the in-flight particle state of the plasma spray process towards designing coatings and achieving coating reliability with the aid of noncontact in-flight particle and spray stream sensors. Key issues such as the phenomena of optimum particle injection and the definition of spray stream using particle state are investigated. Few strategies to modify the microstructure and properties of Yttria Stabilized Zirconia coatings are examined systematically using the framework of process maps. An approach to design process window based on design relevant coating properties is presented. Options to control the process for enhanced reproducibility and reliability are examined and the resultant variability is evaluated systematically at the different stages in the process. The 3D variability due to the difference in plasma characteristics has been critically examined by investigating splats collected from the entire spray footprint.

Microgravity Studies of Liquid-Liquid Phase Transitions in Alumina-Yttria Melts

NASA Technical Reports Server (NTRS)

Guynes, Buddy (Technical Monitor); Weber, Richard; Nordine, Paul

2004-01-01

The scientific objective of this research is to increase the fundamental knowledge base for liquid- phase processing of technologically important oxide materials. The experimental objective is to define conditions and hardware requirements for microgravity flight experiments to test and expand the experimental hypotheses that: 1. Liquid phase transitions can occur in undercooled melts by a diffusionless process. 2. Onset of the liquid phase transition is accompanied by a large change in the temperature dependence of melt viscosity. Experiments on undercooled YAG (Y3A15012)- and rare earth oxide aluminate composition liquids demonstrated a large departure from an Arrhenian temperature dependence of viscosity. Liquid YAG is nearly inviscid at its 2240 K melting point. Glass fibers were pulled from melts undercooled by ca. 600 K indicating that the viscosity is on the order of 100 Pans (1000 Poise) at 1600 K. This value of viscosity is 500 times greater than that obtained by extrapolation of data for temperatures above the melting point of YAG. These results show that the liquids are extremely fragile and that the onset of the highly non-Arrhenian viscosity-temperature relationship occurs at a temperature considerably below the equilibrium melting point of the solid phases. Further results on undercooled alumina-yttria melts containing 23-42 mole % yttrium oxide indicate that a congruent liquid-liquid phase transition occurs in the undercooled liquids. The rates of transition are inconsistent with a diffusion-limited process. This research is directed to investigation of the scientifically interesting phenomena of polyamorphism and fragility in undercooled rare earth oxide aluminum oxide liquids. The results bear on the technologically important problem of producing high value rare earth-based optical materials.

The hydration structure at yttria-stabilized cubic zirconia (110)-water interface with sub-Ångström resolution

DOE PAGES

Hou, Binyang; Kim, Seunghyun; Kim, Taeho; ...

2016-06-15

The interfacial hydration structure of yttria-stabilized cubic zirconia (110) surface in contact with water was determined with ~0.5 Å resolution by high-resolution X-ray reflectivity measurement. The terminal layer shows a reduced electron density compared to the following substrate lattice layers, which indicates there are additional defects generated by metal depletion as well as intrinsic oxygen vacancies, both of which are apparently filled by water species. Above this top surface layer, two additional adsorbed layers are observed forming a characteristic interfacial hydration structure. The first adsorbed layer shows abnormally high density as pure water and likely includes metal species, whereas themore » second layer consists of pure water. The observed interfacial hydration structure seems responsible for local equilibration of the defective surface in water and eventually regulating the long-term degradation processes. As a result, the multitude of water interactions with the zirconia surface results in the complex but highly ordered interfacial structure constituting the reaction front.« less

Effects of artificial aging conditions on yttria-stabilized zirconia implant abutments.

PubMed

Basílio, Mariana de Almeida; Cardoso, Kátia Vieira; Antonio, Selma Gutierrez; Rizkalla, Amin Sami; Santos Junior, Gildo Coelho; Arioli Filho, João Neudenir

2016-08-01

Most ceramic abutments are fabricated from yttria-stabilized tetragonal zirconia (Y-TZP). However, Y-TZP undergoes hydrothermal degradation, a process that is not well understood. The purpose of this in vitro study was to assess the effects of artificial aging conditions on the fracture load, phase stability, and surface microstructure of a Y-TZP abutment. Thirty-two prefabricated Y-TZP abutments were screwed and tightened down to external hexagon implants and divided into 4 groups (n = 8): C, control; MC, mechanical cycling (1×10(6) cycles; 10 Hz); AUT, autoclaving (134°C; 5 hours; 0.2 MPa); and TC, thermal cycling (10(4) cycles; 5°/55°C). A single-load-to-fracture test was performed at a crosshead speed of 0.5 mm/min to assess the assembly's resistance to fracture (ISO Norm 14801). X-ray diffraction (XRD) analysis was applied to observe and quantify the tetragonal-monoclinic (t-m) phase transformation. Representative abutments were examined with high-resolution scanning electron microscopy (SEM) to observe the surface characteristics of the abutments. Load-to-fracture test results (N) were compared by ANOVA and Tukey test (α=.05). XRD measurements revealed the monoclinic phase in some abutments after each aging condition. All the aging conditions reduced the fracture load significantly (P<.001). Mechanical cycling reduced the fracture load more than autoclaving (P=.034). No differences were found in the process of surface degradation among the groups; however, the SEM detected grinding-induced surface flaws and microcracks. The resistance to fracture and the phase stability of Y-TZP implant abutments were susceptible to hydrothermal and mechanical conditions. The surface microstructure of Y-TZP abutments did not change after aging conditions. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Pulsewidth dependence of laser-induced periodic surface structure formed on yttria-stabilized zirconia polycrystal

NASA Astrophysics Data System (ADS)

Kakehata, Masayuki; Yashiro, Hidehiko; Oyane, Ayako; Ito, Atsuo; Torizuka, Kenji

2016-03-01

Three-mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) is a fine engineering ceramic that offers high fracture resistance and flexural strength. Thus, it is often applied in mechanical components and medical implants. The surface roughness can be controlled to improve the device characters in some applications. Ultrashort pulse lasers can form laser-induced periodic surface structures (LIPSS) on 3Y-TZP, which have never been investigated in detail. Therefore, this paper reports the formation and characteristics of LIPSS formed on 3Y-TZP, focusing on the pulsewidth dependence. The LIPSS was formed by a Ti:sapphire chirped-pulse amplification system, which generates 810 nmcentered 80-fs pulses at a 570 Hz repetition rate. The measured ablation threshold peak fluence was ~1.5 J/cm2 and the LIPSS was formed at the peak fluence of 2.7-7.7 J/cm2. For linearly polarized pulses, the lines of the LIPSS were oriented parallel to the polarization direction, and their period was comparable to or larger than the center wavelength of the laser. These characteristics differ from the reported characteristics of LIPSS on metals and dielectrics. The pulsewidth dependence of the ablation and LIPSS was investigated for different pulsewidths and signs of chirp. Under the investigated fluence condition, the LIPSS period increased with increasing pulsewidth for both signs of chirp. Similar pulsewidth dependencies were observed for circularly polarized pulses.

Thickness determination of large-area films of yttria-stabilized zirconia produced by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Pryds, N.; Toftmann, B.; Bilde-Sørensen, J. B.; Schou, J.; Linderoth, S.

2006-04-01

Films of yttria-stabilized zirconia (YSZ) on a polished silicon substrate of diameter up to 125 mm have been produced in a large-area pulsed laser deposition (PLD) setup under typical PLD conditions. The film thickness over the full film area has been determined by energy-dispersive X-ray spectrometry in a scanning electron microscope (SEM) with use of a method similar to one described by Bishop and Poole. The attenuation of the electron-induced X-rays from the Si wafer by the film was monitored at a number of points along a diameter and the thickness was determined by Monte Carlo simulations of the attenuation for various values of film thickness with the program CASINO. These results have been compared with direct measurements in the SEM of the film thickness on a cross-section on one of the wafers. The results of these measurements demonstrate the ability of this technique to accurately determine the thickness of a large film, i.e. up to diameters of 125 mm, in a relatively short time, without destroying the substrate, without the need of a standard sample and without the need of a flat substrate. We have also demonstrated that by controlling the deposition parameters large-area YSZ films with uniform thickness can be produced.

Microstructural development under irradiation in European ODS ferritic/martensitic steels

NASA Astrophysics Data System (ADS)

Schäublin, R.; Ramar, A.; Baluc, N.; de Castro, V.; Monge, M. A.; Leguey, T.; Schmid, N.; Bonjour, C.

2006-06-01

Oxide dispersion strengthened steels based on the ferritic/martensitic steel EUROFER97 are promising candidates for a fusion reactor because of their improved high temperature mechanical properties and their potential higher radiation resistance relative to the base material. Several EUROFER97 based ODS F/M steels are investigated in this study. There are the Plansee ODS steels containing 0.3 wt% yttria, and the CRPP ODS steels, whose production route is described in detail. The reinforcing particles represent 0.3-0.5% weight and are composed of yttria. The effect of 0.3 wt% Ti addition is studied. ODS steel samples have been irradiated with 590 MeV protons to 0.3 and 1.0 dpa at room temperature and 350 °C. Microstructure is investigated by transmission electron microscopy and mechanical properties are assessed by tensile and Charpy tests. While the Plansee ODS presents a ferritic structure, the CRPP ODS material presents a tempered martensitic microstructure and a uniform distribution of the yttria particles. Both materials provide a yield stress higher than the base material, but with reduced elongation and brittle behaviour. Ti additions improve elongation at high temperatures. After irradiation, mechanical properties of the material are only slightly altered with an increase in the yield strength, but without significant decrease in the total elongation, relative to the base material. Samples irradiated at room temperature present radiation induced defects in the form of blacks dots with a size range from 2 to 3 nm, while after irradiation at 350 °C irradiation induced a0<1 0 0>{1 0 0} dislocation loops are clearly visible along with nanocavities. The dispersed yttria particles with an average size of 6-8 nm are found to be stable for all irradiation conditions. The density of the defects and the dispersoid are measured and found to be about 2.3 × 10 22 m -3 and 6.2 × 10 22 m -3, respectively. The weak impact of irradiation on mechanical properties of ODS F

Defect Clustering and Nano-phase Structure Characterization of Multicomponent Rare Earth-Oxide-Doped Zirconia-Yttria Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Chen, Yuan L.; Miller, Robert A.

2004-01-01

Advanced thermal barrier coatings (TBCs) have been developed by incorporating multicomponent rare earth oxide dopants into zirconia-based thermal barrier coatings to promote the creation of the thermodynamically stable, immobile oxide defect clusters and/or nanophases within the coating systems. In this paper, the defect clusters, induced by Nd, Gd, and Yb rare earth dopants in the zirconia-yttria thermal barrier coatings, were characterized by high-resolution transmission electron microscopy (TEM). The TEM lattice imaging, selected area diffraction (SAD), and electron energy-loss spectroscopy (EELS) analyses demonstrated that the extensive nanoscale rare earth dopant segregation exists in the plasma-sprayed and electron-physical-vapor-deposited (EB PVD) thermal barrier coatings. The nanoscale concentration heterogeneity and the resulting large lattice distortion promoted the formation of parallel and rotational defective lattice clusters in the coating systems. The presence of the 5-to 100-nm-sized defect clusters and nanophases is believed to be responsible for the significant reduction of thermal conductivity, improved sintering resistance, and long-term high temperature stability of the advanced thermal barrier coating systems.

Furnace Cyclic Behavior of Plasma-Sprayed Zirconia-Yttria and Multi-Component Rare Earth Oxide Doped Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Nesbitt, James A.; McCue, Terry R.; Barrett, Charles A.; Miller, Robert A.

2002-01-01

Ceramic thermal barrier coatings will play an increasingly important role in advanced gas turbine engines because of their ability to enable further increases in engine temperatures. However, the coating performance and durability become a major concern under the increasingly harsh thermal cycling conditions. Advanced zirconia- and hafnia-based cluster oxide thermal barrier coatings with lower thermal conductivity and improved thermal stability are being developed using a high-heat-flux laser-rig based test approach. Although the new composition coatings were not yet optimized for cyclic durability, an initial durability screening of numerous candidate coating materials was carried out using conventional furnace cyclic tests. In this paper, furnace thermal cyclic behavior of the advanced plasma-sprayed zirconia-yttria-based thermal barrier coatings that were co-doped with multi-component rare earth oxides was investigated at 1163 C using 45 min hot cycles. The ceramic coating failure mechanisms were studied by using scanning electron microscopy combined with X-ray diffraction phase analysis after the furnace tests. The coating cyclic lifetime will be discussed in relation to coating phase structures, total dopant concentrations, and other properties.

Methane Decomposition and Carbon Growth on Y2O3, Yttria-Stabilized Zirconia, and ZrO2

PubMed Central

2014-01-01

Carbon deposition following thermal methane decomposition under dry and steam reforming conditions has been studied on yttria-stabilized zirconia (YSZ), Y2O3, and ZrO2 by a range of different chemical, structural, and spectroscopic characterization techniques, including aberration-corrected electron microscopy, Raman spectroscopy, electric impedance spectroscopy, and volumetric adsorption techniques. Concordantly, all experimental techniques reveal the formation of a conducting layer of disordered nanocrystalline graphite covering the individual grains of the respective pure oxides after treatment in dry methane at temperatures T ≥ 1000 K. In addition, treatment under moist methane conditions causes additional formation of carbon-nanotube-like architectures by partial detachment of the graphite layers. All experiments show that during carbon growth, no substantial reduction of any of the oxides takes place. Our results, therefore, indicate that these pure oxides can act as efficient nonmetallic substrates for methane-induced growth of different carbon species with potentially important implications regarding their use in solid oxide fuel cells. Moreover, by comparing the three oxides, we could elucidate differences in the methane reactivities of the respective SOFC-relevant purely oxidic surfaces under typical SOFC operation conditions without the presence of metallic constituents. PMID:24587591

The Influence of Heat Treatments on the Porosity of Suspension Plasma-Sprayed Yttria-Stabilized Zirconia Coatings

NASA Astrophysics Data System (ADS)

Ekberg, Johanna; Ganvir, Ashish; Klement, Uta; Creci, Simone; Nordstierna, Lars

2018-02-01

Suspension plasma-sprayed coatings are produced using fine-grained feedstock. This allows to control the porosity and to achieve low thermal conductivity which makes the coatings attractive as topcoats in thermal barrier coatings (TBCs). Used in gas turbine applications, TBCs are exposed to high temperature exhaust gases which lead to microstructure alterations. In order to obtain coatings with optimized thermomechanical properties, microstructure alterations like closing of pores and opening of cracks have to be taken into account. Hence, in this study, TBC topcoats consisting of 4 mol.% yttria-stabilized zirconia were heat-treated in air at 1150 °C and thereafter the coating porosity was investigated using image analysis (IA) and nuclear magnetic resonance (NMR) cryoporometry. Both IA and NMR cryoporometry showed that the porosity changed as a result of the heat treatment for all investigated coatings. In fact, both techniques showed that the fine porosity decreased as a result of the heat treatment, while IA also showed an increase in the coarse porosity. When studying the coatings using scanning electron microscopy, it was noticed that finer pores and cracks disappeared and larger pores grew slightly and achieved a more distinct shape as the material seemed to become more compact.

Insight into the grain boundary effect on the ionic transport of yttria-stabilized zirconia at elevated temperatures from a molecular modeling perspective

NASA Astrophysics Data System (ADS)

Chang, Kai-Shiun; Lin, Yi-Feng; Tung, Kuo-Lun

A molecular dynamics (MD) simulation is used to reveal the grain boundary effect on the ionic transport of yttria-stabilized zirconia (YSZ). The oxygen ion displacements and diffusivities of the ideal and grain boundary-inserted YSZ models are analyzed at elevated temperatures. An optimized Y 2O 3 concentration within YSZ for the best ionic conductivity is achieved by balancing the trade-off between the increased vacancies and the decreased accessible free space. The mass transfer resistance of the grain boundary in YSZ can be more easily found at higher temperatures by observing the oxygen ion diffusivities or traveling trajectories. At lower temperatures, the grain interior and the grain boundary control the ionic transport. In contrast, the grain boundary effect on the diffusion barrier is gradually eliminated at elevated temperatures. The modeled results in this work agree well with previous experimental data.

Thermal Oxidation of a Carbon Condensate Formed in High-Frequency Carbon and Carbon-Nickel Plasma Flow

NASA Astrophysics Data System (ADS)

Churilov, G. N.; Nikolaev, N. S.; Cherepakhin, A. V.; Dudnik, A. I.; Tomashevich, E. V.; Trenikhin, M. V.; Bulina, N. G.

2018-02-01

We have reported on the comparative characteristics of thermal oxidation of a carbon condensate prepared by high-frequency arc evaporation of graphite rods and a rod with a hollow center filled with nickel powder. In the latter case, along with different forms of nanodisperse carbon, nickel particles with nickel core-carbon shell structures are formed. It has been found that the processes of the thermal oxidation of carbon condensates with and without nickel differ significantly. Nickel particles with the carbon shell exhibit catalytic properties with respect to the oxidation of nanosized carbon structures. A noticeable difference between the temperatures of the end of the oxidation process for various carbon nanoparticles and nickel particles with the carbon shell has been established. The study is aimed at investigations of the effect of nickel nanoparticles on the dynamics of carbon condensate oxidation upon heating in the argon-oxygen flow.

Structure and chemistry of epitaxial ceria thin films on yttria-stabilized zirconia substrates, studied by high resolution electron microscopy

DOE PAGES

Sinclair, Robert; Lee, Sang Chul; Shi, Yezhou; ...

2017-03-18

Here, we have applied aberration-corrected transmission electron microscopy (TEM) imaging and electron energy loss spectroscopy (EELS) to study the structure and chemistry of epitaxial ceria thin films, grown by pulsed laser deposition onto (001) yttria-stabilized zirconia (YSZ) substrates. There are few observable defects apart from the expected mismatch interfacial dislocations and so the films would be expected to have good potential for applications. Under high electron beam dose rate (above about 6000 e-/Å 2s) domains of an ordered structure appear and these are interpreted as being created by oxygen vacancy ordering. The ordered structure does not appear at lower losemore » rates (ca. 2600 e-/Å 2s) and can be removed by imaging under 1 mbar oxygen gas in an environmental TEM. EELS confirms that there is both oxygen deficiency and the associated increase in Ce 3+ versus Ce 4+ cations in the ordered domains. In situ high resolution TEM recordings show the formation of the ordered domains as well as atomic migration along the ceria thin film (001) surface.« less

Structure and chemistry of epitaxial ceria thin films on yttria-stabilized zirconia substrates, studied by high resolution electron microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sinclair, Robert; Lee, Sang Chul; Shi, Yezhou

Here, we have applied aberration-corrected transmission electron microscopy (TEM) imaging and electron energy loss spectroscopy (EELS) to study the structure and chemistry of epitaxial ceria thin films, grown by pulsed laser deposition onto (001) yttria-stabilized zirconia (YSZ) substrates. There are few observable defects apart from the expected mismatch interfacial dislocations and so the films would be expected to have good potential for applications. Under high electron beam dose rate (above about 6000 e-/Å 2s) domains of an ordered structure appear and these are interpreted as being created by oxygen vacancy ordering. The ordered structure does not appear at lower losemore » rates (ca. 2600 e-/Å 2s) and can be removed by imaging under 1 mbar oxygen gas in an environmental TEM. EELS confirms that there is both oxygen deficiency and the associated increase in Ce 3+ versus Ce 4+ cations in the ordered domains. In situ high resolution TEM recordings show the formation of the ordered domains as well as atomic migration along the ceria thin film (001) surface.« less

Size effect of rebamipide ophthalmic nanodispersions on its therapeutic efficacy for corneal wound healing.

PubMed

Nagai, Noriaki; Ito, Yoshimasa; Okamoto, Norio; Shimomura, Yoshikazu

2016-10-01

In a variety of tissues including gastrointestinal mucosa, rebamipide (REB) provides cytoprotection, prevents inflammation, and promotes wound healing. Clinically, REB ophthalmic dispersions are used to treat diabetic keratopathy. In this study, we investigated the optimal particle size of REB to promote corneal wound healing using a model of diabetic keratopathy, the debrided corneal epithelium from Otsuka Long-Evans Tokushima Fatty (OLETF) rats. First, we prepared three dispersions with different REB particle sizes (REB735, REB150, REB45) by treatment with zirconia beads and Bead Smash 12 (a bead mill). The mean particle sizes of the REB735, REB150, REB45 dispersions were approximately 735 nm, 150 nm and 45 nm, respectively. Next, we measured the amounts of REB in the corneal and conjunctival tissues of rats following the instillation of the REB dispersions. The amounts of REB in the corneal and conjunctival tissues following the instillation of REB dispersions was increased by using the mill method, and the amount of REB in rats instilled with the REB150 dispersion was significantly higher than in rats instilled with the REB45 dispersion. Moreover, the corneal wound healing rate for rats instilled with the REB150 dispersion was significantly higher than for rats instilled with the REB735 or REB45 dispersions. In addition, these REB dispersions enhanced corneal epithelial cell growth, resulting an enhancement of corneal wound healing rate. Thus, we found that the ocular drug accumulation and therapeutic effect on corneal wound healing of REB dispersions is enhanced by preparing particles with a size of ca. 150 nm. These findings provide significant information that can be used to design further studies aimed at developing ophthalmic dispersions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Slurry spin coating of thin film yttria stabilized zirconia/gadolinia doped ceria bi-layer electrolytes for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Kim, Hyun Joong; Kim, Manjin; Neoh, Ke Chean; Han, Gwon Deok; Bae, Kiho; Shin, Jong Mok; Kim, Gyu-Tae; Shim, Joon Hyung

2016-09-01

Thin ceramic bi-layered membrane comprising yttria-stabilized zirconia (YSZ) and gadolinia-doped ceria (GDC) is fabricated by the cost-effective slurry spin coating technique, and it is evaluated as an electrolyte of solid oxide fuel cells (SOFCs). It is demonstrated that the slurry spin coating method is capable of fabricating porous ceramic films by adjusting the content of ethyl-cellulose binders in the source slurry. The porous GDC layer deposited by spin coating under an optimal condition functions satisfactorily as a cathode-electrolyte interlayer in the test SOFC stack. A 2-μm-thick electrolyte membrane of the spin-coated YSZ/GDC bi-layer is successfully deposited as a dense and stable film directly on a porous NiO-YSZ anode support without any interlayers, and the SOFC produces power output over 200 mW cm-2 at 600 °C, with an open circuit voltage close to 1 V. Electrochemical impedance spectra analysis is conducted to evaluate the performance of the fuel cell components in relation with the microstructure of the spin-coated layers.

Enhancing the Bioactivity of Yttria-Stabilized Tetragonal Zirconia Ceramics via Grain-Boundary Activation.

PubMed

Ke, Jinhuan; He, Fupo; Ye, Jiandong

2017-05-17

Yttria-stabilized tetragonal zirconia (Y-TZP) has been proposed as a potential dental implant because of its good biocompatibility, excellent mechanical properties, and distinctive aesthetic effect. However, Y-TZP cannot form chemical bonds with bone tissue because of its biological inertness, which affects the reliability and long-term efficacy of Y-TZP implants. In this study, to improve the bioactivity of Y-TZP ceramics while maintaining their good mechanical performance, Y-TZP was modified by grain-boundary activation via the infiltration of a bioactive glass (BG) sol into the surface layers of Y-TZP ceramics under different negative pressures (atmospheric pressure, -0.05 kPa, and -0.1 kPa), followed by gelling and sintering. The in vitro bioactivity, mechanical properties, and cell behavior of the Y-TZP with improved bioactivity were systematically investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), electron probe microanalysis (EPMA), and Raman spectroscopy. The results of the bioactivity test conducted by immersing Y-TZP in simulated body fluid (SBF) showed that a bonelike apatite layer was produced on the entire surface. The mechanical properties of the modified Y-TZP decreased as the negative pressure in the BG-infiltration process increased relative to those of the Y-TZP blank group. However, the samples infiltrated with the BG sol under -0.05 kPa and atmospheric pressure still retained good mechanical performance. The cell-culture results revealed that the bioactive surface modification of Y-TZP could promote cell adhesion and differentiation. The present work demonstrates that the bioactivity of Y-TZP can be enhanced by grain-boundary activation, and the bioactive Y-TZP is expected to be a potential candidate for use as a dental implant material.

EPR and rheological study of hybrid interfaces in gold-clay-epoxy nanocomposites.

PubMed

Angelov, Verislav; Velichkova, Hristiana; Ivanov, Evgeni; Kotsilkova, Rumiana; Delville, Marie-Hélène; Cangiotti, Michela; Fattori, Alberto; Ottaviani, Maria Francesca

2014-11-11

With the aim to obtain new materials with special properties to be used in various industrial and biomedical applications, ternary "gold-clay-epoxy" nanocomposites and their nanodispersions were prepared using clay decorated with gold nanoparticles (AuNPs), at different gold contents. Nanocomposites structure was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Rheology and electron paramagnetic resonance (EPR) techniques were used in order to evaluate the molecular dynamics in the nanodispersions, as well as dynamics at interfaces in the nanocomposites. The percolation threshold (i.e., the filler content related to the formation of long-range connectivity of particles in the dispersed media) of the gold nanoparticles was determined to be ϕp = 0.6 wt % at a fixed clay content of 3 wt %. The flow activation energy and the relaxation time spectrum illustrated the presence of interfacial interactions in the ternary nanodispersions around and above the percolation threshold of AuNPs; these interfacial interactions suppressed the global molecular dynamics. It was found that below ϕp the free epoxy polymer chains ratio dominated over the chains attracted on the gold surfaces; thus, the rheological behavior was not significantly changed by the presence of AuNPs. While, around and above ϕp, the amount of the bonded epoxy polymer chains on the gold surface was much higher than that of the free chains; thus, a substantial increase in the flow activation energy and shift in the spectra to higher relaxation times appeared. The EPR signals of the nanocomposites depended on the gold nanoparticle contents and the preparation procedure thus providing a fingerprint of the different nanostructures. The EPR results from spin probes indicated that the main effect of the gold nanoparticles above ϕp, was to form a more homogeneous, viscous and polar clay-epoxy mixture at the nanoparticle surface. The knowledge

Fuel electrode containing pre-sintered nickel/zirconia for a solid oxide fuel cell

DOEpatents

Ruka, Roswell J.; Vora, Shailesh D.

2001-01-01

A fuel cell structure (2) is provided, having a pre-sintered nickel-zirconia fuel electrode (6) and an air electrode (4), with a ceramic electrolyte (5) disposed between the electrodes, where the pre-sintered fuel electrode (6) contains particles selected from the group consisting of nickel oxide, cobalt and cerium dioxide particles and mixtures thereof, and titanium dioxide particles, within a matrix of yttria-stabilized zirconia and spaced-apart filamentary nickel strings having a chain structure, and where the fuel electrode can be sintered to provide an active solid oxide fuel cell.

An X-Ray Diffraction Investigation of alpha-Al2O2 Addition to Yttria Stabilized Zirconia (YSZ) Thermal Barrier Coatings Subject to Destabilizing Vanadium Pentoxide (V2O5) Exposure

DTIC Science & Technology

1993-09-01

which is found in several electrical ceramics. flu I ’I I I’ p Figuve 8. System A1aO3-ZrOa Phase Diagram. 11 S. A240.gOiV20 Phas DtagZM The Al3O- V2O5 ...Raot=Lon of V,05 With Y20, Assuming that V205 and Y203 react on an equimolar basis, the creation of yttria vanadate is: V2O5 + YZO3 - 2YV0 4 (2) As...that with a glass phase formation that some phases were "hidden" from XRD analysis and were under-counted, while other phases were over- counted

Investigations in the mechanism of carbothermal reduction of yttria stabilized zirconia for ultra-high temperature ceramics application and its influence on yttria contained in it

NASA Astrophysics Data System (ADS)

Sondhi, Anchal

Zirconium carbide (ZrC) is a high modulus ceramic with an ultra-high melting temperature and, consequently, is capable of withstanding extreme environments. Carbon-carbon composites (CCCs) are important structural materials in current commercial and future hypersonic aircraft; however, these materials may be susceptible to degradation when exposed to elevated temperatures during extreme velocities. At speeds of exceeding Mach 5, intense heating of leading edges of the aircraft triggers rapid oxidation of carbon in CCCs resulting in degradation of the structure and probable failure. Environmental/thermal barrier coatings (EBC/TBC) are employed to protect airfoil structures from extreme conditions. Yttria stabilized zirconia (YSZ) is a well-known EBC/TBC material currently used to protect metallic turbine blades and other aerospace structures. In this work, 3 mol% YSZ has been studied as a potential EBC/TBC on CCCs. However, YSZ is an oxygen conductor and may not sufficiently slow the oxidation of the underlying CCC. Under appropriate conditions, ZrC can form at the interface between CCC and YSZ. Because ZrC is a poor oxygen ion conductor in addition to its stability at high temperatures, it can reduce the oxygen transport to the CCC and thus increase the service lifetime of the structure. This dissertation investigates the thermodynamics and kinetics of the YSZ/ZrC/CCC system and the resulting structural changes across multiple size scales. A series of experiments were conducted to understand the mechanisms and species involved in the carbothermal reduction of ZrO2 to form ZrC. 3 mol% YSZ and graphite powders were uniaxially pressed into pellets and reacted in a graphite (C) furnace. Rietveld x-ray diffraction phase quantification determined that greater fractions of ZrC were formed when carbon was the majority mobile species. These results were validated by modeling the process thermochemically and were confirmed with additional experiments. Measurements were

Double-Layer Gadolinium Zirconate/Yttria-Stabilized Zirconia Thermal Barrier Coatings Deposited by the Solution Precursor Plasma Spray Process

NASA Astrophysics Data System (ADS)

Jiang, Chen; Jordan, Eric H.; Harris, Alan B.; Gell, Maurice; Roth, Jeffrey

2015-08-01

Advanced thermal barrier coatings (TBCs) with lower thermal conductivity, increased resistance to calcium-magnesium-aluminosilicate (CMAS), and improved high-temperature capability, compared to traditional yttria-stabilized zirconia (YSZ) TBCs, are essential to higher efficiency in next generation gas turbine engines. Double-layer rare-earth zirconate/YSZ TBCs are a promising solution. From a processing perspective, solution precursor plasma spray (SPPS) process with its unique and beneficial microstructural features can be an effective approach to obtaining the double-layer microstructure. Previously durable low-thermal-conductivity YSZ TBCs with optimized layered porosity, called the inter-pass boundaries (IPBs) were produced using the SPPS process. In this study, an SPPS gadolinium zirconate (GZO) protective surface layer was successfully added. These SPPS double-layer TBCs not only retained good cyclic durability and low thermal conductivity, but also demonstrated favorable phase stability and increased surface temperature capabilities. The CMAS resistance was evaluated with both accumulative and single applications of simulated CMAS in isothermal furnaces. The double-layer YSZ/GZO exhibited dramatic improvement in the single application, but not in the continuous one. In addition, to explore their potential application in integrated gasification combined cycle environments, double-layer TBCs were tested under high-temperature humidity and encouraging performance was recorded.

Calculations of single crystal elastic constants for yttria partially stabilised zirconia from powder diffraction data

NASA Astrophysics Data System (ADS)

Lunt, A. J. G.; Xie, M. Y.; Baimpas, N.; Zhang, S. Y.; Kabra, S.; Kelleher, J.; Neo, T. K.; Korsunsky, A. M.

2014-08-01

Yttria Stabilised Zirconia (YSZ) is a tough, phase-transforming ceramic that finds use in a wide range of commercial applications from dental prostheses to thermal barrier coatings. Micromechanical modelling of phase transformation can deliver reliable predictions in terms of the influence of temperature and stress. However, models must rely on the accurate knowledge of single crystal elastic stiffness constants. Some techniques for elastic stiffness determination are well-established. The most popular of these involve exploiting frequency shifts and phase velocities of acoustic waves. However, the application of these techniques to YSZ can be problematic due to the micro-twinning observed in larger crystals. Here, we propose an alternative approach based on selective elastic strain sampling (e.g., by diffraction) of grain ensembles sharing certain orientation, and the prediction of the same quantities by polycrystalline modelling, for example, the Reuss or Voigt average. The inverse problem arises consisting of adjusting the single crystal stiffness matrix to match the polycrystal predictions to observations. In the present model-matching study, we sought to determine the single crystal stiffness matrix of tetragonal YSZ using the results of time-of-flight neutron diffraction obtained from an in situ compression experiment and Finite Element modelling of the deformation of polycrystalline tetragonal YSZ. The best match between the model predictions and observations was obtained for the optimized stiffness values of C11 = 451, C33 = 302, C44 = 39, C66 = 82, C12 = 240, and C13 = 50 (units: GPa). Considering the significant amount of scatter in the published literature data, our result appears reasonably consistent.

Activity of plasma sprayed yttria stabilized zirconia reinforced hydroxyapatite/Ti-6Al-4V composite coatings in simulated body fluid.

PubMed

Gu, Y W; Khor, K A; Pan, D; Cheang, P

2004-07-01

Hydroxyapatite (HA)/yttria stabilized zirconia/Ti-6Al-4V bio-composite coatings deposited onto Ti-6Al-4V substrate through a plasma spray technique were immersed in simulated body fluid (SBF) to investigate their behavior in vitro. Surface morphologies and structural changes in the coatings were analyzed by scanning electron microscopy, thin-film X-ray diffractometer, and X-ray photoelectron spectroscopy. The tensile bond strength of the coatings after immersion was also conducted through the ASTM C-633 standard for thermal sprayed coatings. Results showed that carbonate-containing hydroxyapatite (CHA) layer formed on the surface of composite coatings after 4 weeks immersion in SBF solution, indicating the composite coating possessed excellent bioactivity. The mechanical properties were found to decrease with immersion duration of maximum 56 days. However, minimal variation in mechanical properties was found subsequent to achieving supersaturation of the calcium ions, which was attained with the precipitation of the calcium phosphate layers. The mechanical properties of the composite coating were found to be significantly higher than those of pure HA coatings even after immersion in the SBF solution, indicating the enhanced mechanical properties of the composite coatings.

Titanium diboride-chromium diboride-yttrium titanium oxide ceramic composition and a process for making the same

DOEpatents

Holcombe, Cressie E.; Dykes, Norman L.

1991-01-01

A ceramic composition is described. The ceramic composition consists essentially of from about 84 to 96 w/o titanium diboride, from about 1 to 9 w/o chromium diboride, and from about 3 to about 15 w/o yttrium-titanium-oxide. A method of making the ceramic composition is also described. The method of making the ceramic composition comprises the following steps: Step 1--A consolidated body containing stoichiometric quantities of titanium diboride and chromium diboride is provided. Step 2--The consolidated body is enclosed in and in contact with a thermally insulated package of yttria granules having a thickness of at least 0.5 inches. Step 3--The consolidated body enclosed in the thermally insulated package of yttria granules is heated in a microwave oven with microwave energy to a temperature equal to or greater than 1,900 degrees centigrade to sinter and uniformly disperse yttria particles having a size range from about 1 to about 12 microns throughout the consolidated body forming a densified body consisting essentially of titanium diboride, chromium diboride, and yttrium-titanium-oxide. The resulting densified body has enhanced fracture toughness and hardness.

Process for making a titanium diboride-chromium diboride-yttrium titanium oxide ceramic composition

DOEpatents

Holcombe, Cressie E.; Dykes, Norman L.

1992-01-01

A ceramic composition composition is described. The ceramic composition consists essentially of from about 84 to 96 w/o titanium diboride, from about 1 to 9 w/o chromium diboride, and from about 3 to aobut 15 w/o yttrium-titanium-oxide. A method of making the ceramic composition is also described. The method of making the ceramic composition comprises the following steps: Step 1--A consolidated body containing stoichiometric quantities of titanium diboride and chromium diboride is provided. Step 2--The consolidated body is enclosed in and in contact with a thermally insulated package of yttria granules having a thickness of at least 0.5 inches. Step 3--The consolidated body enclosed in the thermally insulated package of yttria granules is heated in a microwave oven with microwave energy to a temperature equal to or greater than 1,900 degrees centigrade to sinter and uniformly disperse yttria particles having a size range from about 1 to about 12 microns throughout the consolidated body forming a densified body consisting essentially of titanium diboride, chromium diboride, and yttrium-titanium-oxide. The resulting densified body has enhanced fracture toughness and hardness.

Process for making a titanium diboride-chromium diboride-yttrium titanium oxide ceramic composition

DOEpatents

Holcombe, C.E.; Dykes, N.L.

1992-04-28

A ceramic composition is described. The ceramic composition consists essentially of from about 84 to 96 w/o titanium diboride, from about 1 to 9 w/o chromium diboride, and from about 3 to about 15 w/o yttrium-titanium-oxide. A method of making the ceramic composition is also described. The method of making the ceramic composition comprises the following steps: Step 1--A consolidated body containing stoichiometric quantities of titanium diboride and chromium diboride is provided. Step 2--The consolidated body is enclosed in and in contact with a thermally insulated package of yttria granules having a thickness of at least 0.5 inches. Step 3--The consolidated body enclosed in the thermally insulated package of yttria granules is heated in a microwave oven with microwave energy to a temperature equal to or greater than 1,900 degrees centigrade to sinter and uniformly disperse yttria particles having a size range from about 1 to about 12 microns throughout the consolidated body forming a densified body consisting essentially of titanium diboride, chromium diboride, and yttrium-titanium-oxide. The resulting densified body has enhanced fracture toughness and hardness. No Drawings

Effects of whitening dentifrice on yttria-stabilized tetragonal zirconia polycrystal surfaces after simulating brushing.

PubMed

Pinelli, Lígia Antunes Pereira; Gimenes Olbera, Amanda Caroline; Candido, Lucas Miguel; Miotto, Larissa Natiele; Antonio, Selma Gutierrez; Fais, Laiza Maria Grassi

2017-01-01

The changes that occur after brushing yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) are unknown. These changes may favor the retention of microorganisms and chemisorption of water, impairing its longevity. The purpose of this in vitro study was to evaluate the effects of a whitening dentifrice on Y-TZP surfaces after simulating 10 years of brushing. Seventy-two bar-shaped specimens (20×4×1.2 mm) were divided into 4 groups: storage in distilled water (SW, control), brushing with distilled water (BW), brushing with dentifrice (BD), and brushing with whitening dentifrice (BWD). Brushing was conducted using a linear brushing machine (878400 cycles, 0.98 N, soft toothbrush). The mean roughness (Ra) was analyzed with a profilometer and the superficial topography with scanning electron microscopy (SEM) at baseline and after treatment. Crystalline phases were characterized using x-ray diffraction. Baseline and posttreatment Ra were analyzed using the 1-way ANOVA and Tukey HSD multiple comparison test; the paired t test was used for intragroup comparison (all α=.05). The Ra (μm) means (before/after treatment) were SW 0.28/0.28; BW 0.32/0.31; BD 0.28/0.36; BWD 0.30/0.20. No statistically significant difference was found for Ra at baseline (P=.108) than for posttreatment results (P<.001); the BD group had higher Ra values when compared with baseline (P=.019); the BWD group had the lowest values (P<.001). The BD surfaces showed pronounced scratches and detachment of the surface, while BWD showed smoother surfaces; similar crystallographic results among groups were observed. Brushing Y-TZP with conventional dentifrice increased roughness, while brushing with whitening dentifrice reduced roughness. Neither dentifrice changed the crystallographic phases after brushing. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Investigating the effect of suspensions nanostructure on the thermophysical properties of nanofluids

NASA Astrophysics Data System (ADS)

Tesfai, Waka; Singh, Pawan K.; Masharqa, Salim J. S.; Souier, Tewfik; Chiesa, Matteo; Shatilla, Youssef

2012-12-01

The effect of fractal dimensions and Feret diameter of aggregated nanoparticle on predicting the thermophysical properties of nanofluids is demonstrated. The fractal dimensions and Feret diameter distributions of particle agglomerates are quantified from scanning electron and probe microscope imaging of yttria nanofluids. The results are compared with the fractal dimensions calculated by fitting the rheological properties of yttria nanofluids against the modified Krieger-Dougherty model. Nanofluids of less than 1 vol. % particle loading are found to have fractal dimensions of below 1.8, which is typical for diffusion controlled cluster formation. By contrast, an increase in the particle loading increases the fractal dimension to 2.0-2.2. The fractal dimensions obtained from both methods are employed to predict the thermal conductivity of the nanofluids using the modified Maxwell-Garnet (M-G) model. The prediction from rheology is found inadequate and might lead up to 8% error in thermal conductivity for an improper choice of aspect ratio. Nevertheless, the prediction of the modified M-G model from the imaging is found to agree well with the experimentally observed effective thermal conductivity of the nanofluids. In addition, this study opens a new window on the study of aggregate kinetics, which is critical in tuning the properties of multiphase systems.

Assessing the feasibility of yttria-stabilized zirconia in novel designs as mandibular anterior fixed lingual retention following orthodontic treatment

NASA Astrophysics Data System (ADS)

Stout, Matthew

The purpose of this study is to explore the feasibility of yttria-stabilized zirconia (Y-TZP) in fixed lingual retention as an alternative to stainless steel. Exploratory Y-TZP specimens were milled to establish design parameters. Next, specimens were milled according to ASTM standard C1161-13 and subjected to four-point flexural test to determine materials properties. Finite Element (FE) Analysis was employed to evaluate nine novel cross-sectional designs and compared to stainless steel wire. Each design was analyzed under the loading conditions to determine von Mises and bond stress. The most promising design was fabricated to assess accuracy and precision of current CAD/CAM milling technology. The superior design had a 1.0 x 0.5 mm semi-elliptical cross section and was shown to be fabricated reliably. Overall, the milling indicated a maximum percent standard deviation of 9.3 and maximum percent error of 13.5 with a cost of $30 per specimen. Y-TZP can be reliably milled to dimensions comparable to currently available metallic retainer wires. Further research is necessary to determine the success of bonding protocol and clinical longevity of Y-TZP fixed retainers. Advanced technology is necessary to connect the intraoral scan to an aesthetic and patient-specific Y-TZP fixed retainer.

Hydrogen oxidation mechanisms on Ni/yttria stabilized zirconia anodes: Separation of reaction pathways by geometry variation of pattern electrodes

NASA Astrophysics Data System (ADS)

Doppler, M. C.; Fleig, J.; Bram, M.; Opitz, A. K.

2018-03-01

Nickel/yttria stabilized zirconia (YSZ) electrodes are affecting the overall performance of solid oxide fuel cells (SOFCs) in general and strongly contribute to the cell resistance in case of novel metal supported SOFCs in particular. The electrochemical fuel conversion mechanisms in these electrodes are, however, still only partly understood. In this study, micro-structured Ni thin film electrodes on YSZ with 15 different geometries are utilized to investigate reaction pathways for the hydrogen electro-oxidation at Ni/YSZ anodes. From electrodes with constant area but varying triple phase boundary (TPB) length a contribution to the electro-catalytic activity is found that does not depend on the TPB length. This additional activity could clearly be attributed to a yet unknown reaction pathway scaling with the electrode area. It is shown that this area related pathway has significantly different electrochemical behavior compared to the TPB pathway regarding its thermal activation, sulfur poisoning behavior, and H2/H2O partial pressure dependence. Moreover, possible reaction mechanisms of this reaction pathway are discussed, identifying either a pathway based on hydrogen diffusion through Ni with water release at the TPB or a path with oxygen diffusion through Ni to be a very likely explanation for the experimental results.

Calculations of single crystal elastic constants for yttria partially stabilised zirconia from powder diffraction data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lunt, A. J. G., E-mail: alexander.lunt@eng.ox.ac.uk; Xie, M. Y.; Baimpas, N.

2014-08-07

Yttria Stabilised Zirconia (YSZ) is a tough, phase-transforming ceramic that finds use in a wide range of commercial applications from dental prostheses to thermal barrier coatings. Micromechanical modelling of phase transformation can deliver reliable predictions in terms of the influence of temperature and stress. However, models must rely on the accurate knowledge of single crystal elastic stiffness constants. Some techniques for elastic stiffness determination are well-established. The most popular of these involve exploiting frequency shifts and phase velocities of acoustic waves. However, the application of these techniques to YSZ can be problematic due to the micro-twinning observed in larger crystals.more » Here, we propose an alternative approach based on selective elastic strain sampling (e.g., by diffraction) of grain ensembles sharing certain orientation, and the prediction of the same quantities by polycrystalline modelling, for example, the Reuss or Voigt average. The inverse problem arises consisting of adjusting the single crystal stiffness matrix to match the polycrystal predictions to observations. In the present model-matching study, we sought to determine the single crystal stiffness matrix of tetragonal YSZ using the results of time-of-flight neutron diffraction obtained from an in situ compression experiment and Finite Element modelling of the deformation of polycrystalline tetragonal YSZ. The best match between the model predictions and observations was obtained for the optimized stiffness values of C11 = 451, C33 = 302, C44 = 39, C66 = 82, C12 = 240, and C13 = 50 (units: GPa). Considering the significant amount of scatter in the published literature data, our result appears reasonably consistent.« less

Corrosion Behavior of Yttria-Stabilized Zirconia-Coated 9Cr-1Mo Steel in Molten UCl3-LiCl-KCl Salt

NASA Astrophysics Data System (ADS)

Jagadeeswara Rao, Ch.; Venkatesh, P.; Prabhakara Reddy, B.; Ningshen, S.; Mallika, C.; Kamachi Mudali, U.

2017-02-01

For the electrorefining step in the pyrochemical reprocessing of spent metallic fuels of future sodium cooled fast breeder reactors, 9Cr-1Mo steel has been proposed as the container material. The electrorefining process is carried out using 5-6 wt.% UCl3 in LiCl-KCl molten salt as the electrolyte at 500 °C under argon atmosphere. In the present study, to protect the container vessel from hot corrosion by the molten salt, 8-9% yttria-stabilized zirconia (YSZ) ceramic coating was deposited on 9Cr-1Mo steel by atmospheric plasma spray process. The hot corrosion behavior of YSZ-coated 9Cr-1Mo steel specimen was investigated in molten UCl3-LiCl-KCl salt at 600 °C for 100-, 500-, 1000- and 2000-h duration. The results revealed that the weight change in the YSZ-coated specimen was insignificant even after exposure to molten salt for 2000 h, and delamination of coating did not occur. SEM examination showed the lamellar morphology of the YSZ coating after the corrosion test with occluded molten salt. The XRD analysis confirmed the presence of tetragonal and cubic phases of ZrO2, without any phase change. Formation of UO2 in some regions of the samples was evident from XRD results.

Effect of far-field stresses and residual stresses incorporation in predicting fracture toughness of carbon nanotube reinforced yttria stabilized zirconia

NASA Astrophysics Data System (ADS)

Mahato, Neelima; Nisar, Ambreen; Mohapatra, Pratyasha; Rawat, Siddharth; Ariharan, S.; Balani, Kantesh

2017-10-01

Yttria-stabilized zirconia (YSZ) is a potential thermal insulating ceramic for high temperature applications (>1000 °C). YSZ reinforced with multi-walled carbon nanotubes (MWNTs) was processed via spark plasma sintering to produce dense, crack-free homogeneous sample and avoid any degradation of MWNTs when sintered using conventional routes. Despite porosity, the addition of MWNT has a profound effect in improving the damage tolerance of YSZ by allowing the retention of tetragonal phase. However, at some instances, the crack lengths in the MWNT reinforced YSZ matrices have been found to be longer than the standalone counterparts. Therefore, it becomes inappropriate to apply Anstis equation to calculate fracture toughness values. In this regard, a combined analytical cum numerical method is used to estimate the theoretical fracture toughness and quantitatively analyze the mechanics of matrix cracking in the reinforced composite matrices incorporating the effects of various factors (such as far-field stresses, volume fraction of MWNTs, change in the modulus and Poisson's ratio values along with the increase in porosity, and bridging and phase transformation mechanism) affecting the fracture toughness of YSZ-MWNT composites. The results suggest that the incorporation of far-field stresses cannot be ignored in estimating the theoretical fracture toughness of YSZ-MWNT composites.

Preparation of nanodispersions by solvent displacement using the Venturi tube.

PubMed

García-Salazar, Gilberto; de la Luz Zambrano-Zaragoza, María; Quintanar-Guerrero, David

2018-05-02

The Venturi tube (VT) is an apparatus that produces turbulence which is taken advantage of to produce nanoparticles (NP) by solvent displacement. The objective of this study was to evaluate the potential of this device for preparing NP of poly-ε-caprolactone. Response Surface Methodology was used to determine the effect of the operating conditions and optimization. The NP produced by VT were characterized by Dynamic Light-Scattering to determine their particle size distribution (PS) and polydispersity index (PDI). Results showed that the Reynolds number (Re) has a strong effect on both PS and process yield (PY).The turbulence regime is key to the efficient formation of NP. The optimal conditions for obtaining NP were a polymer concentration of 1.6 w/v, a recirculation rate of 4.8 L/min, and a stabilizer concentration of 1.1 w/v. The predicted response of the PY was 99.7%, with a PS of 333 nm, and a PDI of 0.2. Maintaining the same preparation conditions will make it possible to obtain NP using other polymers with similar properties. Our results show that VT is a reproducible and versatile method for manufacturing NP, and so may be a feasible method for industrial-scale nanoprecipitation production. Copyright © 2018 Elsevier B.V. All rights reserved.

Tube manufacturing and characterization of oxide dispersion strengthened ferritic steels

NASA Astrophysics Data System (ADS)

Ukai, Shigeharu; Mizuta, Shunji; Yoshitake, Tunemitsu; Okuda, Takanari; Fujiwara, Masayuki; Hagi, Shigeki; Kobayashi, Toshimi

2000-12-01

Oxide dispersion strengthened (ODS) ferritic steels have an advantage in radiation resistance and superior creep rupture strength at elevated temperature due to finely distributed Y2O3 particles in the ferritic matrix. Using a basic composition of low activation ferritic steel (Fe-12Cr-2W-0.05C), cladding tube manufacturing by means of pilger mill rolling and subsequent recrystallization heat-treatment was conducted while varying titanium and yttria contents. The recrystallization heat-treatment, to soften the tubes hardened due to cold-rolling and to subsequently improve the degraded mechanical properties, was demonstrated to be effective in the course of tube manufacturing. For a titanium content of 0.3 wt% and yttria of 0.25 wt%, improvement of the creep rupture strength can be attained for the manufactured cladding tubes. The ductility is also adequately maintained.

Ionic Conductivity Increased by Two Orders of Magnitude in Micrometer-Thick Vertical Yttria-Stabilized ZrO 2 Nanocomposite Films

DOE PAGES

Lee, Shinbuhm; Zhang, Wenrui; Khatkhatay, Fauzia; ...

2015-09-03

We design and create a unique cell geometry of templated micrometer-thick epitaxial nanocomposite films which contain ~20 nm diameter yttria-stabilized ZrO 2 (YSZ) nanocolumns, strain coupled to a SrTiO 3 matrix. We also enhanced the ionic conductivity of these nanocolumnsby over 2 orders of magnitude compared to plain YSZ films. Concomitant with the higher ionic conduction is the finding that the YSZ nanocolumns in the films have much higher crystallinity and orientation, compared to plain YSZ films. Hence, “oxygen migration highways” are formed in the desired out-of-plane direction. This improved structure is shown to originate from the epitaxial coupling ofmore » the YSZ nanocolumns to the SrTiO 3 film matrix and from nucleation of the YSZ nanocolumns on an intermediate nanocomposite base layer of highly aligned Sm-doped CeO 2 nanocolumns within the SrTiO 3 matrix. Furthermore, this intermediate layer reduces the lattice mismatch between the YSZ nanocolumns and the substrate. Vertical ionic conduction values as high as 10 –2 Ω –1 cm –1 were demonstrated at 360 °C (300 °C lower than plain YSZ films), showing the strong practical potential of these nanostructured films for use in much lower operation temperature ionic devices.« less

Investigation of the oxygen exchange mechanism on Pt|yttria stabilized zirconia at intermediate temperatures: Surface path versus bulk path

PubMed Central

Opitz, Alexander K.; Lutz, Alexander; Kubicek, Markus; Kubel, Frank; Hutter, Herbert; Fleig, Jürgen

2011-01-01

The oxygen exchange kinetics of platinum on yttria-stabilized zirconia (YSZ) was investigated by means of geometrically well-defined Pt microelectrodes. By variation of electrode size and temperature it was possible to separate two temperature regimes with different geometry dependencies of the polarization resistance. At higher temperatures (550–700 °C) an elementary step located close to the three phase boundary (TPB) with an activation energy of ∼1.6 eV was identified as rate limiting. At lower temperatures (300–400 °C) the rate limiting elementary step is related to the electrode area and exhibited a very low activation energy in the order of 0.2 eV. From these observations two parallel pathways for electrochemical oxygen exchange are concluded. The nature of these two elementary steps is discussed in terms of equivalent circuits. Two combinations of parallel rate limiting reaction steps are found to explain the observed geometry dependencies: (i) Diffusion through an impurity phase at the TPB in parallel to diffusion of oxygen through platinum – most likely along Pt grain boundaries – as area-related process. (ii) Co-limitation of oxygen diffusion along the Pt|YSZ interface and charge transfer at the interface with a short decay length of the corresponding transmission line (as TPB-related process) in parallel to oxygen diffusion through platinum. PMID:22210951

Fracture toughness improvements of dental ceramic through use of yttria-stabilized zirconia (YSZ) thin-film coatings.

PubMed

Chan, Ryan N; Stoner, Brian R; Thompson, Jeffrey Y; Scattergood, Ronald O; Piascik, Jeffrey R

2013-08-01

The aim of this study was to evaluate strengthening mechanisms of yttria-stabilized zirconia (YSZ) thin film coatings as a viable method for improving fracture toughness of all-ceramic dental restorations. Bars (2mm×2mm×15mm, n=12) were cut from porcelain (ProCAD, Ivoclar-Vivadent) blocks and wet-polished through 1200-grit using SiC abrasive. A Vickers indenter was used to induce flaws with controlled size and geometry. Depositions were performed via radio frequency magnetron sputtering (5mT, 25°C, 30:1 Ar/O2 gas ratio) with varying powers of substrate bias. Film and flaw properties were characterized by optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Flexural strength was determined by three-point bending. Fracture toughness values were calculated from flaw size and fracture strength. Data show improvements in fracture strength of up to 57% over unmodified specimens. XRD analysis shows that films deposited with higher substrate bias displayed a high %monoclinic volume fraction (19%) compared to non-biased deposited films (87%), and resulted in increased film stresses and modified YSZ microstructures. SEM analysis shows critical flaw sizes of 67±1μm leading to fracture toughness improvements of 55% over unmodified specimens. Data support surface modification of dental ceramics with YSZ thin film coatings to improve fracture toughness. Increase in construct strength was attributed to increase in compressive film stresses and modified YSZ thin film microstructures. It is believed that this surface modification may lead to significant improvements and overall reliability of all-ceramic dental restorations. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Oxide dispersion strengthened nickel produced by nonreactive milling

NASA Technical Reports Server (NTRS)

Arias, A.

1976-01-01

It is shown that oxide dispersion strengthened alloys can be produced by a postulated nonreactive milling mechanism whereby the dispersoid is trapped at the interface between welding metal powder particles. This interparticle welding is possible because, without a suitable and sufficiently vigorous chemical reaction between the metal powder particles and the milling fluid, no protective, weld-preventing reaction coating is formed on these particles. Using water as the nonreactive milling fluid, Ni - 1.8-vol % thoria and Ni - 1.8-vol % yttria alloys with 1093 C tensile strengths ranging from 122.3 to 141.5 MN/sq m (17,900 to 20,500 psi) were produced by nonreactive milling.

Phase evolution and thermal properties of yttria-stabilized hafnia nano-coatings deposited on alumina

NASA Astrophysics Data System (ADS)

Rubio, Ernesto Javier

High-temperature coatings are critical to the future power-generation systems and industries. Thermal barrier coatings (TBCs), which are usually the ceramic materials applied as thin coatings, protect engine components and allow further increase in engine temperatures for higher efficiency. Thus, the durability and reliability of the coating systems have to be more robust compared to current natural gas based engines. While a near and mid-term target is to develop TBC architecture with a 1300 °C surface temperature tolerance, a deeper understanding of the structure evolution and thermal behavior of the TBC-bond coat interface, specifically the thermally grown oxide (TGO), is of primary importance. In the present work, attention is directed towards yttria-stabilized hafnia (YSH) coatings on alumina (α-Al2O 3) to simulate the TBC-TGO interface and understand the phase evolution, microstructure and thermal oxidation of the coatings. YSH coatings were grown on α-Al2O3 substrates by sputter deposition by varying coating thickness in a wide range ˜30-1000 nm. The effect of coating thickness on the structure, morphology and the residual stress has been investigated using X-ray diffraction (XRD) and high resolution scanning electron microscopy (SEM). Thermal oxidation behavior of the coatings has been evaluated using the isothermal oxidation measurements under static conditions. X-ray diffraction analyses revealed the existence of monoclinic hafnia phase for relatively thin coatings indicating that the interfacial phenomena are dominant in phase stabilization. The evolution towards pure stabilized cubic phase of hafnia with the increasing coating thickness is observed. The SEM results indicate the changes in morphology of the coatings; the average grain size increases from 15 to 500 nm with increasing thickness. Residual stress was calculated employing XRD using the variable ψ-angle. Relation between residual stress and structural change is also studied. The results

High performance novel gadolinium doped ceria/yttria stabilized zirconia/nickel layered and hybrid thin film anodes for application in solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Garcia-Garcia, F. J.; Beltrán, A. M.; Yubero, F.; González-Elipe, A. R.; Lambert, R. M.

2017-09-01

Magnetron sputtering under oblique angle deposition was used to produce Ni-containing ultra thin film anodes comprising alternating layers of gadolinium doped ceria (GDC) and yttria stabilized zirconia (YSZ) of either 200 nm or 1000 nm thickness. The evolution of film structure from initial deposition, through calcination and final reduction was examined by XRD, SEM, TEM and TOF-SIMS. After subsequent fuel cell usage, the porous columnar architecture of the two-component layered thin film anodes was maintained and their resistance to delamination from the underlying YSZ electrolyte was superior to that of corresponding single component Ni-YSZ and Ni-GDC thin films. Moreover, the fuel cell performance of the 200 nm layered anodes compared favorably with conventional commercially available thick anodes. The observed dependence of fuel cell performance on individual layer thicknesses prompted study of equivalent but more easily fabricated hybrid anodes consisting of simultaneously deposited Ni-GDC and Ni-YSZ, which procedure resulted in exceptionally intimate mixing and interaction of the components. The hybrids exhibited very unusual and favorable Isbnd V characteristics, along with exceptionally high power densities at high currents. Their discovery is the principal contribution of the present work.

Stabilizing Ir(001) Epitaxy on Yttria-Stabilized Zirconia Using a Thin Ir Seed Layer Grown by Pulsed Laser Deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, Lisha; Jacobs, Christopher B.; Rouleau, Christopher M.

In this paper, we demonstrate the reproducible epitaxial growth of 100 nm thick Ir(001) films on a heteroepitaxial stack consisting of 5 nm Ir and 100 nm yttria-stabilized zirconia (YSZ) grown on Si(001) substrates. It is shown that a 5 nm thick Ir layer grown by pulsed laser deposition in the same chamber as the YSZ film without breaking the vacuum is the key to stabilizing Ir(001) epitaxial growth. Growth of the Ir seed layer with pure (001) orientation occurs only in a narrow growth temperature window from 550 to 750 °C, and the fraction of Ir(111) increases at substratemore » temperatures outside of this window. The Ir seed layer prevents exposure of the YSZ film to air during sample transfer and enables highly reproducible Ir(001) heteroepitaxy on YSZ buffered Si(001). In contrast, if Ir is grown directly on a bare YSZ layer that was exposed to ambient conditions, the films are prone to change orientation to (111). These results reveal that preserving the chemical and structural purity of the YSZ surface is imperative for achieving Ir(001) epitaxy. The narrow range of the mosaic spread values from eight experiments demonstrates the high yield and high reproducibility of Ir(001) heteroepitaxy by this approach. Lastly, the improved Ir(001) epitaxial growth method is of great significance for integrating a variety of technologically important materials such as diamond, graphene, and functional oxides on a Si platform.« less

Stabilizing Ir(001) Epitaxy on Yttria-Stabilized Zirconia Using a Thin Ir Seed Layer Grown by Pulsed Laser Deposition

DOE PAGES

Fan, Lisha; Jacobs, Christopher B.; Rouleau, Christopher M.; ...

2016-11-18

In this paper, we demonstrate the reproducible epitaxial growth of 100 nm thick Ir(001) films on a heteroepitaxial stack consisting of 5 nm Ir and 100 nm yttria-stabilized zirconia (YSZ) grown on Si(001) substrates. It is shown that a 5 nm thick Ir layer grown by pulsed laser deposition in the same chamber as the YSZ film without breaking the vacuum is the key to stabilizing Ir(001) epitaxial growth. Growth of the Ir seed layer with pure (001) orientation occurs only in a narrow growth temperature window from 550 to 750 °C, and the fraction of Ir(111) increases at substratemore » temperatures outside of this window. The Ir seed layer prevents exposure of the YSZ film to air during sample transfer and enables highly reproducible Ir(001) heteroepitaxy on YSZ buffered Si(001). In contrast, if Ir is grown directly on a bare YSZ layer that was exposed to ambient conditions, the films are prone to change orientation to (111). These results reveal that preserving the chemical and structural purity of the YSZ surface is imperative for achieving Ir(001) epitaxy. The narrow range of the mosaic spread values from eight experiments demonstrates the high yield and high reproducibility of Ir(001) heteroepitaxy by this approach. Lastly, the improved Ir(001) epitaxial growth method is of great significance for integrating a variety of technologically important materials such as diamond, graphene, and functional oxides on a Si platform.« less

Determination of Scattering and Absorption Coefficients for Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings at Elevated Temperatures

NASA Technical Reports Server (NTRS)

Eldridge, Jeffrey I.; Spuckler, Charles M.; Markham, James R.

2009-01-01

The temperature dependence of the scattering and absorption coefficients for a set of freestanding plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) was determined at temperatures up to 1360 C in a wavelength range from 1.2 micrometers up to the 8YSZ absorption edge. The scattering and absorption coefficients were determined by fitting the directional-hemispherical reflectance and transmittance values calculated by a four-flux Kubelka Munk method to the experimentally measured hemispherical-directional reflectance and transmittance values obtained for five 8YSZ thicknesses. The scattering coefficient exhibited a continuous decrease with increasing wavelength and showed no significant temperature dependence. The scattering is primarily attributed to the relatively temperature-insensitive refractive index mismatch between the 8YSZ and its internal voids. The absorption coefficient was very low (less than 1 per centimeter) at wavelengths between 2 micrometers and the absorption edge and showed a definite temperature dependence that consisted of a shift of the absorption edge to shorter wavelengths and an increase in the weak absorption below the absorption edge with increasing temperature. The shift in the absorption edge with temperature is attributed to strongly temperature-dependent multiphonon absorption. While TBC hemispherical transmittance beyond the absorption edge can be predicted by a simple exponential decrease with thickness, below the absorption edge, typical TBC thicknesses are well below the thickness range where a simple exponential decrease in hemispherical transmittance with TBC thickness is expected. [Correction added after online publication August 11, 2009: "edge to a shorter wavelengths" has been updated as edge to shorter wavelengths."

Method of making a cermet fuel electrode containing an inert additive

DOEpatents

Jensen, R.R.

1992-08-25

An electrode is attached to a solid electrolyte material by: (1) mixing a metallic nickel component and 1 wt% to 10 wt% of yttria stabilized zirconia having particle diameters up to 3 micrometers with an organic binder solution to form a slurry, (2) applying the slurry to a solid zirconia electrolyte material, (3) heating the slurry to drive off the organic binder and form a porous layer of metallic nickel substantially surrounded and separated by the zirconia particles, and (4) electro-chemical vapor depositing a skeletal structure between and around the metallic nickel and the zirconia particles where the metallic nickel components do not substantially sinter to each other, yet the layer remains porous. 4 figs.

Method of making a cermet fuel electrode containing an inert additive

DOEpatents

Jensen, Russel R.

1992-01-01

An electrode is attached to a solid electrolyte material by: (1) mixing a metallic nickel component and 1 wt% to 10 wt% of yttria stabilized zirconia having particle diameters up to 3 micrometers with an organic binder solution to form a slurry, (2) applying the slurry to a solid zirconia electrolyte material, (3) heating the slurry to drive off the organic binder and form a porous layer of metallic nickel substantially surrounded and separated by the zirconia particles, and (4) electro-chemical vapor depositing a skeletal structure between and around the metallic nickel and the zirconia particles where the metallic nickel components do not substantially sinter to each other, yet the layer remains porous.

Re-activation of degraded nickel cermet anodes - Nano-particle formation via reverse current pulses

NASA Astrophysics Data System (ADS)

Hauch, A.; Marchese, M.; Lanzini, A.; Graves, C.

2018-02-01

The Ni/yttria-stabilized-zirconia (YSZ) cermet is the most commonly applied fuel electrode for solid oxide cells (SOCs). Loss of Ni/YSZ electrode activity is a key life-time limiting factor of the SOC. Developing means to mitigate this loss of performance or re-activate a fuel electrode is therefore important. In this work, we report a series of five tests on state-of-the-art Ni/YSZ-YSZ-CGObarrier-LSC/CGO cells. All cells were deliberately degraded via gas stream impurities in CO2/CO or harsh steam electrolysis operation. The cells were re-activated via a variety of reverse current treatments (RCTs). Via electrochemical impedance spectroscopy, we found that the Ni/YSZ electrode performance could be recovered via RCT, but not via constant fuel cell operation. For optimized RCT, we obtained a lower Ni/YSZ electrode resistance than the initial resistance. E.g. at 700 °C we measured fuel electrode resistance of 180 mΩ cm2, 390 mΩ cm2, and 159 mΩ cm2 before degradation, after degradation and after re-activation via RCT, respectively. Post-test SEM revealed that the RCT led to formation of nano-particles in the fuel electrode. Besides the remarkable improvement, the results also showed that RCTs can weaken Ni/YSZ interfaces and the electrode/electrolyte interface. This indicates that finding an optimum RCT profile is crucial for achieving maximum benefit.

Generation of colour centres in yttria-stabilized zirconia by heavy ion irradiations in the GeV range.

PubMed

Costantini, Jean-Marc; Beuneu, François; Schwartz, Kurt; Trautmann, Christina

2010-08-11

We have studied the colour centre production in yttria-stabilized zirconia (ZrO(2):Y(3 +)) by heavy ion irradiation in the GeV range using on-line UV-visible optical absorption spectroscopy. Experiments were performed with 11.4 MeV amu(-1) (127)Xe, (197)Au, (208)Pb and (238)U ion irradiations at 8 K or room temperature (RT). A broad and asymmetrical absorption band peaked at a wavelength about 500 nm is recorded regardless of the irradiation parameters, in agreement with previous RT irradiations with heavy ions in the 100 MeV range. This band is de-convoluted into two broad Gaussian-shaped bands centred at photon energies about 2.4 and 3.1 eV that are respectively associated with the F(+)-type centres (involving a singly ionized oxygen vacancy, VO· and T centres (i.e. Zr(3+) in a trigonal symmetry) observed by electron paramagnetic resonance (EPR) spectroscopy. In the case of 8 K Au ion irradiation at low fluences, six bands are used at about 1.9, 2.3, 2.7, 3.1 and 4.0 eV. The three bands near 2.0-2.5 eV can be assigned to oxygen divacancies (i.e. F(2)(+) centres). No significant effect of the irradiation temperature is found on the widths of all absorption bands for the same ion and fluence. This is attributed to the inhomogeneous broadening arising from the static disorder due to the native charge-compensating oxygen vacancies. However, the colour centre production yield is strongly enhanced at 8 K with respect to RT. When heating irradiated samples from 8 K to RT, the extra colour centres produced at low temperature do not recover completely to the level of RT irradiation. The latter results are accounted for by an electronically driven defect recovery process.

Analysis of high temperature deformation mechanism in ODS EUROFER97 alloy

NASA Astrophysics Data System (ADS)

Ramar, A.; Spätig, P.; Schäublin, R.

2008-12-01

Oxide dispersion in tempered martensitic EUROFER97 steel is an efficient approach to improve its strength. The oxide dispersion strengthened (ODS) EUROFER97 steel shows a good strength up to 600 °C, but degrades rapidly beyond that temperature. To understand the origin in the microstructure of this drop in strength in situ heating experiment in TEM was performed from room temperature to 1000 °C. Upon heating neither microstructure changes nor dislocation movement are observed up to 600 °C. Movement of dislocations are observed above 680 °C. Phase transformation to austenite starts at 840 °C. Yttria particles remain stable up to 1000 °C. Changes in mechanical properties thus do not relate to changes in yttria dispersion. It is attempted to relate these observations to the thermal activation parameters measured by the technique of conventional strain rate experiment, which allow to identify at a mesoscopic scale the microstructural mechanisms responsible for the degradation of ODS steel at high temperatures.

Practical method of CO.sub.2 sequestration

DOEpatents

Goswami, D Yogi [Gainesville, FL; Lee, Man Su [Houston, TX; Kothurkar, Nikhil K [Tampa, FL; Stefanakos, Elias K [Tampa, FL

2011-03-01

A process and device to capture of CO.sub.2 at its originating source, such as a power plant, is disclosed. Absorbent material is recharged by desorbing CO.sub.2, so that it may be sequestered or used in another application. Continual recharging results in loss of absorbent surface area, due to pore plugging and sintering of particles. Calcium oxide or calcium hydroxide was immobilized to a fibrous ceramic-based fabric substrate as a thin film and sintered, creating an absorbent material. The samples were characterized, showing continuous cyclic carbonation conversions between about 62% and 75% under mild calcination conditions at 750.degree. C. and no CO.sub.2 in N.sub.2. Under the more severe calcination condition at 850.degree. C. and 20 wt % CO.sub.2 in N.sub.2, yttria fabric was superior to alumina as a substrate for carbon dioxide capture and the reactivity of the calcium oxide absorbent immobilized to yttria was maintained at the same level in the 12 cycles.

Particle size distribution control of Pt particles used for particle gun

NASA Astrophysics Data System (ADS)

Ichiji, M.; Akiba, H.; Nagao, H.; Hirasawa, I.

2017-07-01

The purpose of this study is particle size distribution (PSD) control of submicron sized Pt particles used for particle gun. In this report, simple reaction crystallization is conducted by mixing H2PtCl6 and ascorbic acid. Without the additive, obtained Pt particles have broad PSD and reproducibility of experiment is low. With seeding, Pt particles have narrow PSD and reproducibility improved. Additionally, mean particle diameter of 100-700 nm is controlled by changing seeding amount. Obtained particles are successfully characterized as Pt by XRD results. Moreover, XRD spectra indicate that obtained particles are polycrystals. These experimental results suggest that seeding consumed nucleation, as most nuclei attached on the seed surface. This mechanism virtually restricted nucleation to have narrow PSD can be obtained.

Effect of autoclave induced low-temperature degradation on the adhesion energy between yttria-stabilized zirconia veneered with porcelain.

PubMed

Li, Kai Chun; Waddell, J Neil; Prior, David J; Ting, Stephanie; Girvan, Liz; van Vuuren, Ludwig Jansen; Swain, Michael V

2013-11-01

To investigate the effect of autoclave induced low-temperature degradation on the adhesion energy between yttria-stabilized zirconia veneered with porcelain. The strain energy release rate using a four-point bending stable fracture test was evaluated for two different porcelains [leucite containing (VM9) and glass (Zirox) porcelain] veneered to zirconia. Prior to veneering the zirconia had been subjected to 0 (control), 1, 5, 10 and 20 autoclave cycles. The specimens were manufactured to a total bi-layer dimension of 30 mm × 8 mm × 3 mm. Subsequent scanning electron microscopy/energy dispersive spectrometry, electron backscatter diffraction and X-ray diffraction analysis were performed to identify the phase transformation and fracture behavior. The strain energy release rate for debonding of the VM9 specimens were significantly higher (p<0.05) compared to the Zirox specimens across all test groups. Increasing autoclave cycles lowered the strain energy release rate significantly (p<0.05) from 18.67 J/m(2) (control) to the lowest of 12.79 J/m(2) (cycle 10) for only the VM9 specimens. SEM analyses showed predominant cohesive fracture within the porcelain for all cycle groups. XRD analysis of the substrate prior to veneering confirmed a tetragonal to monoclinic phase transformation with increasing the number of autoclave cycles between 5 and 20. The monoclinic phase reverted back to tetragonal phase after undergoing conventional porcelain firing cycles. EBSD data showed significant changes of the grain size distribution between the control and autoclaved specimen (cycle 20). Increasing autoclave cycles only significantly decreased the adhesion of the VM9 layered specimens. In addition, a conventional porcelain firing schedule completely reverted the monoclinic phase back to tetragonal. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Physical vapor deposition and metalorganic chemical vapor deposition of yttria-stabilized zirconia thin films

NASA Astrophysics Data System (ADS)

Kaufman, David Y.

Two vapor deposition techniques, dual magnetron oblique sputtering (DMOS) and metalorganic chemical vapor deposition (MOCVD), have been developed to produce yttria-stabilized zirconia (YSZ) films with unique microstructures. In particular, biaxially textured thin films on amorphous substrates and dense thin films on porous substrates have been fabricated by DMOS and MOCVD, respectively. DMOS YSZ thin films were deposited by reactive sputtering onto Si (native oxide surface) substrates positioned equidistant between two magnetron sources such that the fluxes arrived at oblique angles with respect to the substrate normal. Incident fluxes from two complimentary oblique directions were necessary for the development of biaxial texture. The films displayed a strong [001] out-of-plane orientation with the <110> direction in the film aligned with the incident flux. Biaxial texture improved with increasing oblique angle and film thickness, and was stronger for films deposited with Ne than with Ar. The films displayed a columnar microstructure with grain bundling perpendicular to the projected flux direction, the degree of which increased with oblique angle and thickness. The texture decreased by sputtering at pressures at which the flux of sputtered atoms was thermalized. These results suggested that grain alignment is due to directed impingement of both sputtered atoms and reflected energetic neutrals. The best texture, a {111} phi FWHM of 23°, was obtained in a 4.8 mum thick film deposited at an oblique angle of 56°. MOCVD YSZ thin films were deposited in a vertical cold-wall reactor using Zr(tmhd)4 and Y(tmhd)3 precursors. Fully stabilized YSZ films with 9 mol% could be deposited by controlling the bubbler temperatures. YSZ films on Si substrates displayed a transition at 525°C from surface kinetic limited growth, with an activation energy of 5.5 kJ/mole, to mass transport limited growth. Modifying the reactor by lowering the inlet height and introducing an Ar baffle

PENTACLE: Parallelized particle-particle particle-tree code for planet formation

NASA Astrophysics Data System (ADS)

Iwasawa, Masaki; Oshino, Shoichi; Fujii, Michiko S.; Hori, Yasunori

2017-10-01

We have newly developed a parallelized particle-particle particle-tree code for planet formation, PENTACLE, which is a parallelized hybrid N-body integrator executed on a CPU-based (super)computer. PENTACLE uses a fourth-order Hermite algorithm to calculate gravitational interactions between particles within a cut-off radius and a Barnes-Hut tree method for gravity from particles beyond. It also implements an open-source library designed for full automatic parallelization of particle simulations, FDPS (Framework for Developing Particle Simulator), to parallelize a Barnes-Hut tree algorithm for a memory-distributed supercomputer. These allow us to handle 1-10 million particles in a high-resolution N-body simulation on CPU clusters for collisional dynamics, including physical collisions in a planetesimal disc. In this paper, we show the performance and the accuracy of PENTACLE in terms of \\tilde{R}_cut and a time-step Δt. It turns out that the accuracy of a hybrid N-body simulation is controlled through Δ t / \\tilde{R}_cut and Δ t / \\tilde{R}_cut ˜ 0.1 is necessary to simulate accurately the accretion process of a planet for ≥106 yr. For all those interested in large-scale particle simulations, PENTACLE, customized for planet formation, will be freely available from https://github.com/PENTACLE-Team/PENTACLE under the MIT licence.

Novel nanodispersed coal liquefaction catalysts: Molecular design via microemulsion-based synthesis. Final technical report, October 1990--December 1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osseo-Asare, K.; Boakye, E.; Vittal, M.

1995-04-01

This report described the synthesis of Molybdenum Sulfides in microemulsions by acidification of ammonium tetrathiomolybdate. Molybdenum Sulfides have been shown to be potential coal liquefaction catalysts. The importance of particle size, temperature effects, and coal surface chemistry to impregnation are discussed.

Organically Modified Nanoclay-Reinforced Rigid Polyurethane Films

NASA Astrophysics Data System (ADS)

Park, Yong Tae; Qian, Yuqiang; Lindsay, Chris; Stein, Andreas; Macosko, Christopher

2012-02-01

The nanodispersion of vermiculite in polyurethanes was investigated to produce organoclay-reinforced rigid gas barrier films. Reducing gas transport can improve the insulation performance of closed cell polyurethane foam. In a previous study, the dispersion of vermiculite in polyurethanes without organic modification was not sufficient due to the non-uniform dispersion morphology. When vermiculite was modified by cation exchange with long-chain quaternary ammonium cations, the dispersion in methylene diphenyl diisocyanate (MDI) was significantly improved. Dispersion was improved by combining high intensity dispersive mixing with efficient distributive mixing. Polymerization conditions were also optimized in order to provide a high state of nanodispersion in the polyurethane nanocomposite. The dispersions were characterized using rheological, microscopic and scattering/diffraction techniques. The final nanocomposites showed enhancement of mechanical properties and reduction in permeability to carbon dioxide at low clay concentration (around 2 wt percent).

Accelerated aging characteristics of three yttria-stabilized tetragonal zirconia polycrystalline dental materials.

PubMed

Flinn, Brian D; deGroot, Dirk A; Mancl, Lloyd A; Raigrodski, Ariel J

2012-10-01

Concerns have been expressed about the effect of aging on the mechanical properties of zirconia. The purpose of this study was to assess the accelerated aging characteristics of 3 commercially available yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) materials by exposing specimens to hydrothermal treatments at 134°C, 0.2 MPa and 180°C, 1.0 MPa in steam. Thin bars of Y-TZP from 3 manufacturers, Lava, Zirkonzahn, and Zirprime, n=30 for each brand (22 × 3 × 0.2 mm), were cut and ground from blocks and sintered according to the manufacturer's specifications. Control specimens (n=10) for each brand were evaluated in the as-received condition. Experimental specimens were artificially aged at standard autoclave sterilization conditions,134°C at 0.2 MPa (n=5 per group at 50, 100, 150, and 200 hours) and standard industrial ceramic aging conditions, 180°C at 1.0 MPa (n=5 per group at 8, 16, 24, 28, and 48 hours). Tetragonal to monoclinic transformation was measured by using X-ray diffraction (XRD) for all groups. Flexural strength was measured in 4-point bending (ASTM1161-B) for all groups. Fracture surfaces were examined by scanning electron microscopy (SEM). Data were analyzed as a function of aging time. The statistical comparisons were based on the log value and 2-way ANOVA with heteroscedasticity-consistent standard errors used to compare mean strength among conditions (α=.05). After 200 hours at 134°C and 0.2 MPa, flexural strength (SD) decreased significantly from 1156 (87.6) MPa to 829.5 (71) MPa for Lava; 1406 (243) MPa to 882.7 (91) MPa for Zirkonzahn; and 1126 (92.4) MPa to 976 (36.4) MPa for Zirprime with P<.001 for all 3 comparisons. After 200 hours at 134°C and 0.2 MPa, some tetragonal crystals transformed to the monoclinic phase. The relative XRD peak intensity of the monoclinic to tetragonal crystal phases increased from 0.07 to 1.82 for Lava, from 0.06 to 2.43 for Zirkonzahn, and from 0.05 to 0.53 for Zirprime. After 28 hours at 180�

A particle-particle collision strategy for arbitrarily shaped particles at low Stokes numbers

NASA Astrophysics Data System (ADS)

Daghooghi, Mohsen; Borazjani, Iman

2016-11-01

We present a collision strategy for particles with any general shape at low Stokes numbers. Conventional collision strategies rely upon a short -range repulsion force along particles centerline, which is a suitable choice for spherical particles and may not work for complex-shaped particles. In the present method, upon the collision of two particles, kinematics of particles are modified so that particles have zero relative velocity toward each other along the direction in which they have the minimum distance. The advantage of this novel technique is that it guaranties to prevent particles from overlapping without unrealistic bounce back at low Stokes numbers, which may occur if repulsive forces are used. This model is used to simulate sedimentation of many particles in a vertical channel and suspensions of non-spherical particles under simple shear flow. This work was supported by the American Chemical Society (ACS) Petroleum Research Fund (PRF) Grant Number 53099-DNI9. The computational resources were partly provided by the Center for Computational Research (CCR) at the University at Buffalo.

Volatile particles measured by vapor-particle separator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Meng -Dawn; Corporan, Edwin

Vapor-Particle Separator (VPS) is a new technology developed for characterization of the volatile fraction of particulate matter in a combustion aerosol population. VPS incorporates a novel metallic membrane and operates in a cross-flow filtration mode for separation of vapor and solid (i.e. non-volatile) particles. Demonstration of the VPS technology on aircraft engine-emitted particles has led to the improvement of the technology and increased confidence on the robustness of its field performance. In this study, the performance of the VPS was evaluated against the Particle Measurement Programme (PMP) volatile particle remover (VPR), a standardized device used in heavy duty diesel enginesmore » for separation and characterization of non-volatile particulate matter. Using tetracontane particles in the laboratory reveals that the VPS performed reasonably well in removing the volatile species. In the field conditions, a single-mode particle size distribution was found for emitted particles from a T63 turboshaft engine at both idle and cruise engine power conditions. Removal of the volatile T63 engine particles by the VPS was consistent with that of PMP VPR. In tests on an F117 turbofan engine, the size distribution at the idle (4% rated) engine power condition was found to be bimodal, with the first mode consisting of particles smaller than 10nm, which are believed to be mostly semi-volatile particles, while the second mode of larger size was a mixture of semi-volatile and non-volatile particles. The distribution was single modal at the 33% rated engine power with no secondary mode observed. Altogether, for particles emitted by both engines, the removal efficiency of the VPS appears to surpass that of the PMP VPR by 8-10%.« less

Volatile particles measured by vapor-particle separator

DOE PAGES

Cheng, Meng -Dawn; Corporan, Edwin

2016-08-25

Vapor-Particle Separator (VPS) is a new technology developed for characterization of the volatile fraction of particulate matter in a combustion aerosol population. VPS incorporates a novel metallic membrane and operates in a cross-flow filtration mode for separation of vapor and solid (i.e. non-volatile) particles. Demonstration of the VPS technology on aircraft engine-emitted particles has led to the improvement of the technology and increased confidence on the robustness of its field performance. In this study, the performance of the VPS was evaluated against the Particle Measurement Programme (PMP) volatile particle remover (VPR), a standardized device used in heavy duty diesel enginesmore » for separation and characterization of non-volatile particulate matter. Using tetracontane particles in the laboratory reveals that the VPS performed reasonably well in removing the volatile species. In the field conditions, a single-mode particle size distribution was found for emitted particles from a T63 turboshaft engine at both idle and cruise engine power conditions. Removal of the volatile T63 engine particles by the VPS was consistent with that of PMP VPR. In tests on an F117 turbofan engine, the size distribution at the idle (4% rated) engine power condition was found to be bimodal, with the first mode consisting of particles smaller than 10nm, which are believed to be mostly semi-volatile particles, while the second mode of larger size was a mixture of semi-volatile and non-volatile particles. The distribution was single modal at the 33% rated engine power with no secondary mode observed. Altogether, for particles emitted by both engines, the removal efficiency of the VPS appears to surpass that of the PMP VPR by 8-10%.« less

Particle separation

NASA Technical Reports Server (NTRS)

Arnott, W. Patrick (Inventor); Chakrabarty, Rajan K. (Inventor); Moosmuller, Hans (Inventor)

2011-01-01

Embodiments of a method for selecting particles, such as based on their morphology, is disclosed. In a particular example, the particles are charged and acquire different amounts of charge, or have different charge distributions, based on their morphology. The particles are then sorted based on their flow properties. In a specific example, the particles are sorted using a differential mobility analyzer, which sorts particles, at least in part, based on their electrical mobility. Given a population of particles with similar electrical mobilities, the disclosed process can be used to sort particles based on the net charge carried by the particle, and thus, given the relationship between charge and morphology, separate the particles based on their morphology.

Particle separation

DOEpatents

Moosmuller, Hans [Reno, NV; Chakrabarty, Rajan K [Reno, NV; Arnott, W Patrick [Reno, NV

2011-04-26

Embodiments of a method for selecting particles, such as based on their morphology, is disclosed. In a particular example, the particles are charged and acquire different amounts of charge, or have different charge distributions, based on their morphology. The particles are then sorted based on their flow properties. In a specific example, the particles are sorted using a differential mobility analyzer, which sorts particles, at least in part, based on their electrical mobility. Given a population of particles with similar electrical mobilities, the disclosed process can be used to sort particles based on the net charge carried by the particle, and thus, given the relationship between charge and morphology, separate the particles based on their morphology.

Observation of yttrium oxide nanoparticles in cabbage (Brassica oleracea) through dual energy K-edge subtraction imaging

DOE PAGES

Chen, Yunyun; Sanchez, Carlos; Yue, Yuan; ...

2016-03-25

Background: The potential transfer of engineered nanoparticles (ENPs) from plants into the food chain has raised widespread concerns. In order to investigate the effects of ENPs on plants, young cabbage plants (Brassica oleracea) were exposed to a hydroponic system containing yttrium oxide (yttria) ENPs. The objective of this study was to reveal the impacts of NPs on plants by using K-edge subtraction imaging technique. Results: Using synchrotron dual-e nergy X-ray micro-tomography with K-edge subtraction technique, we studied the uptake, accumulation, distribution and concentration mapping of yttria ENPs in cabbage plants. It was found that yttria ENPs were uptaken by themore » cabbage roots but did not effectively transferred and mobilized through the cabbage stem and leaves. This could be due to the accumulation of yttria ENPs blocked at primary-lateral-root junction. Instead, non-yttria minerals were found in the xylem vessels of roots and stem. Conclusions: Synchrotron dual-energy X-ray micro-tomography is an effective method to observe yttria NPs inside the cabbage plants in both whole body and microscale level. Furthermore, the blockage of a plant's roots by nanoparticles is likely the first and potentially fatal environmental effect of such type of nanoparticles.« less

Dielectrophoretic particle-particle interaction under AC electrohydrodynamic flow conditions.

PubMed

Lee, Doh-Hyoung; Yu, Chengjie; Papazoglou, Elisabeth; Farouk, Bakhtier; Noh, Hongseok M

2011-09-01

We used the Maxwell stress tensor method to understand dielectrophoretic particle-particle interactions and applied the results to the interpretation of particle behaviors under alternating current (AC) electrohydrodynamic conditions such as AC electroosmosis (ACEO) and electrothermal flow (ETF). Distinct particle behaviors were observed under ACEO and ETF. Diverse particle-particle interactions observed in experiments such as particle clustering, particles keeping a certain distance from each other, chain and disc formation and their rotation, are explained based on the numerical simulation data. The improved understanding of particle behaviors in AC electrohydrodynamic flows presented here will enable researchers to design better particle manipulation strategies for lab-on-a-chip applications. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Primordial Particles; Collisions of Inelastic Particles

NASA Astrophysics Data System (ADS)

Sagi, George

2011-03-01

Three-dimensional matter is not defined by Euclidian or Cartesian geometries. Newton's and Einstein's laws are related to the motions of elastic masses. The study of collisions of inelastic particles opens up new vistas in physics. The present article reveals how such particles create clusters composed of various numbers of particles. The Probability of each formation, duplets, triplets, etc. can be calculated. The particles are held together by a binding force, and depending upon the angles of collisions they may also rotate around their center of geometry. Because of these unique properties such inelastic particles are referred to as primordial particles, Pp. When a given density of Pp per cubic space is given, then random collisions create a field. The calculation of the properties of such primordial field is very complex and beyond the present study. However, the angles of collisions are infinite in principle, but the probabilities of various cluster sizes are quantum dependent. Consequently, field calculations will require new complex mathematical methods to be discovered yet.

Big Bang Day: 5 Particles - 3. The Anti-particle

ScienceCinema

None

2017-12-09

Simon Singh looks at the stories behind the discovery of 5 of the universe's most significant subatomic particles: the Electron, the Quark, the Anti-particle, the Neutrino and the "next particle". 3. The Anti-particle. It appears to be the stuff of science fiction. Associated with every elementary particle is an antiparticle which has the same mass and opposite charge. Should the two meet and combine, the result is annihilation - and a flash of light. Thanks to mysterious processes that occurred after the Big Bang there are a vastly greater number of particles than anti-particles. So how could their elusive existence be proved? At CERN particle physicists are crashing together subatomic particles at incredibly high speeds to create antimatter, which they hope will finally reveal what happened at the precise moment of the Big Bang to create the repertoire of elementary particles and antiparticles in existence today.

Big Bang Day: 5 Particles - 5. The Next Particle

ScienceCinema

None

2017-12-09

Simon Singh looks at the stories behind the discovery of 5 of the universe's most significant subatomic particles: the Electron, the Quark, the Anti-particle, the Neutrino and the "next particle". 5. The Next Particle The "sparticle" - a super symmetric partner to all the known particles could be the answer to uniting all the known particles and their interactions under one grand theoretical pattern of activity. But how do researchers know where to look for such phenomena and how do they know if they find them? Simon Singh reviews the next particle that physicists would like to find if the current particle theories are to ring true.

Dense zig-zag microstructures in YSZ thin films by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Stender, Dieter; Schäuble, Nina; Weidenkaff, Anke; Montagne, Alex; Ghisleni, Rudy; Michler, Johann; Schneider, Christof W.; Wokaun, Alexander; Lippert, Thomas

2015-01-01

The very brittle oxygen ion conductor yttria stabilized zirconia (YSZ) is a typical solid electrolyte for miniaturized thin film fuel cells. In order to decrease the fuel cell operating temperature, the thickness of yttria stabilized zirconia thin films is reduced. Often, these thin membranes suffer from mechanical failure and gas permeability. To improve these mechanical issues, a glancing angle deposition approach is used to grow yttria stabilized zirconia thin films with tilted columnar structures. Changes of the material flux direction during the deposition result in a dense, zigzag-like structure with columnar crystallites. This structure reduces the elastic modulus of these membranes as compared to columnar yttria stabilized zirconia thin films as monitored by nano-indentation which makes them more adaptable to applied stress.

Big Bang Day: 5 Particles - 3. The Anti-particle

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2009-10-07

Simon Singh looks at the stories behind the discovery of 5 of the universe's most significant subatomic particles: the Electron, the Quark, the Anti-particle, the Neutrino and the "next particle". 3. The Anti-particle. It appears to be the stuff of science fiction. Associated with every elementary particle is an antiparticle which has the same mass and opposite charge. Should the two meet and combine, the result is annihilation - and a flash of light. Thanks to mysterious processes that occurred after the Big Bang there are a vastly greater number of particles than anti-particles. So how could their elusive existencemore » be proved? At CERN particle physicists are crashing together subatomic particles at incredibly high speeds to create antimatter, which they hope will finally reveal what happened at the precise moment of the Big Bang to create the repertoire of elementary particles and antiparticles in existence today.« less

Method of preparing porous, rigid ceramic separators for an electrochemical cell. [Patent application

DOEpatents

Bandyopadhyay, G.; Dusek, J.T.

Porous, rigid separators for electrochemical cells are prepared by first calcining particles of ceramic material at temperatures above about 1200/sup 0/C for a sufficient period of time to reduce the sinterability of the particles. A ceramic powder that has not been calcined is blended with the original powder to control the porosity of the completed separator. The ceramic blend is then pressed into a sheet of the desired shape and sintered at a temperature somewhat lower than the calcination temperature. Separator sheets of about 1 to 2.5 mm thickness and 30 to 70% porosity can be prepared by this technique. Ceramics such as yttria, magnesium oxide, and magnesium-aluminium oxide have advantageously been used to form separators by this method.

Method of preparing porous, rigid ceramic separators for an electrochemical cell

DOEpatents

Bandyopadhyay, Gautam; Dusek, Joseph T.

1981-01-01

Porous, rigid separators for electrochemical cells are prepared by first calcining particles of ceramic material at temperatures above about 1200.degree. C. for a sufficient period of time to reduce the sinterability of the particles. A ceramic powder that has not been calcined is blended with the original powder to control the porosity of the completed separator. The ceramic blend is then pressed into a sheet of the desired shape and sintered at a temperature somewhat lower than the calcination temperature. Separator sheets of about 1 to 2.5 mm thickness and 30 to 70% porosity can be prepared by this technique. Ceramics such as yttria, magnesium oxide and magnesium-aluminum oxide have advantageously been used to form separators by this method.

Big Bang Day: 5 Particles - 5. The Next Particle

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2009-10-08

Simon Singh looks at the stories behind the discovery of 5 of the universe's most significant subatomic particles: the Electron, the Quark, the Anti-particle, the Neutrino and the "next particle". 5. The Next Particle The "sparticle" - a super symmetric partner to all the known particles could be the answer to uniting all the known particles and their interactions under one grand theoretical pattern of activity. But how do researchers know where to look for such phenomena and how do they know if they find them? Simon Singh reviews the next particle that physicists would like to find if themore » current particle theories are to ring true.« less

Microstructure and rheology of particle stabilized emulsions: Effects of particle shape and inter-particle interactions.

PubMed

Katepalli, Hari; John, Vijay T; Tripathi, Anubhav; Bose, Arijit

2017-01-01

Using fumed and spherical silica particles of similar hydrodynamic size, we investigated the effects of particle shape and inter-particle interactions on the formation, stability and rheology of bromohexadecane-in-water Pickering emulsions. The interparticle interactions were varied from repulsive to attractive by modifying the salt concentration in the aqueous phase. Optical microscope images revealed smaller droplet sizes for the fumed silica stabilized emulsions. All the emulsions remained stable for several weeks. Cryo-SEM images of the emulsion droplets showed a hexagonally packed single layer of particles at oil-water interfaces in emulsions stabilized with silica spheres, irrespective of the nature of the inter-particle interactions. Thus, entropic, excluded volume interactions dominate the fate of spherical particles at oil-water interfaces. On the other hand, closely packed layers of particles were observed at oil-water interfaces for the fumed silica stabilized emulsions for both attractive and repulsive interparticle interactions. At the high salt concentrations, attractive inter-particles interactions led to aggregation of fumed silica particles, and multiple layers of these particles were then observed on the droplet surfaces. A network of fumed silica particles was also observed between the emulsion droplets, suggesting that enthalpic interactions are responsible for the determining particle configurations at oil-water interfaces as well as in the aqueous phase. Steady shear viscosity measurements over a range of shear stresses, as well as oscillatory shear measurements at 1Hz confirm the presence of a network in fumed silica suspensions and emulsions, and the lack of such a network when spherical particles are used. The fractal structure of fumed silica leads to several contact points and particle interlocking in the water as well as on the bromohexadecane-water interfaces, with corresponding effects on the structure and rheology of the emulsions

Degradation of yttria-stabilized zirconia thermal barrier coatings by vanadium pentoxide, phosphorous pentoxide, and sodium sulfate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohan, P.; Yuan, B.; Patterson, T.

2007-11-15

The presence of vanadium, phosphorus, and sodium impurities in petcoke and coal/petcoke blends used in integrated gasification combined cycle (IGCC) plants warrants a clear understanding of high-temperature material degradation for the development of fuel-flexible gas turbines. In this study, degradation reactions of free-standing air plasma-sprayed (APS) yttria-stabilized zirconia (YSZ) in contact with V{sub 2}O{sub 5}, P{sub 2}O{sub 5}, and Na{sub 2}SO{sub 4} were investigated at temperatures up to 1200{sup o}C. Phase transformations and microstructural development were examined using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Molten V{sub 2}O{sub 5} reacted with solid YSZ to form ZrV{sub 2}O{sub 7}more » at temperatures below 747{sup o}C. However, at temperatures above 747{sup o}C, molten V{sub 2}O{sub 5} reacted with YSZ to form yttrium vanadate (YVO{sub 4}). The formation of YVO{sub 4} led to the depletion of the Y2O{sub 3} stabilizer and deleterious transformation to the monoclinic ZrO{sub 2} phase. In addition, studies on YSZ degradation by Na{sub 2}SO{sub 4} and a Na{sub 2}SO{sub 4}+V{sub 2}O{sub 5} mixture (50-50 mol%) showed that Na{sub 2}SO{sub 4} itself had no effect on the degradation of YSZ. However, in the presence of V{sub 2}O{sub 5} at high temperatures, Na{sub 2}SO{sub 4} forms vanadate compounds having a lower melting point such as sodium metavanadate (610{sup o}C), which was found to degrade YSZ by the formation of YVO{sub 4} at a relatively lower temperature of 700{sup o}C. P{sub 2}O{sub 5} was found to react with APS YSZ by the formation of ZrP{sub 2}O{sub 7} at all the temperatures studied. At temperatures as low as 200{sup o}C and as high as 1200{sup o}C, molten P{sub 2}O{sub 5} was observed to react with solid YSZ to yield ZrP{sub 2}O{sub 7}, which led to the depletion of ZrO{sub 2} in YSZ that promoted the formation of the fluorite-cubic ZrO{sub 2} phase.« less

Interaction of Multiple Particles with a Solidification Front: From Compacted Particle Layer to Particle Trapping.

PubMed

Saint-Michel, Brice; Georgelin, Marc; Deville, Sylvain; Pocheau, Alain

2017-06-13

The interaction of solidification fronts with objects such as particles, droplets, cells, or bubbles is a phenomenon with many natural and technological occurrences. For an object facing the front, it may yield various fates, from trapping to rejection, with large implications regarding the solidification pattern. However, whereas most situations involve multiple particles interacting with each other and the front, attention has focused almost exclusively on the interaction of a single, isolated object with the front. Here we address experimentally the interaction of multiple particles with a solidification front by performing solidification experiments of a monodisperse particle suspension in a Hele-Shaw cell with precise control of growth conditions and real-time visualization. We evidence the growth of a particle layer ahead of the front at a close-packing volume fraction, and we document its steady-state value at various solidification velocities. We then extend single-particle models to the situation of multiple particles by taking into account the additional force induced on an entering particle by viscous friction in the compacted particle layer. By a force balance model this provides an indirect measure of the repelling mean thermomolecular pressure over a particle entering the front. The presence of multiple particles is found to increase it following a reduction of the thickness of the thin liquid film that separates particles and front. We anticipate the findings reported here to provide a relevant basis to understand many complex solidification situations in geophysics, engineering, biology, or food engineering, where multiple objects interact with the front and control the resulting solidification patterns.

Laminar convective heat transfer of non-Newtonian nanofluids with constant wall temperature

NASA Astrophysics Data System (ADS)

Hojjat, M.; Etemad, S. Gh.; Bagheri, R.; Thibault, J.

2011-02-01

Nanofluids are obtained by dispersing homogeneously nanoparticles into a base fluid. Nanofluids often exhibit higher heat transfer rate in comparison with the base fluid. In the present study, forced convection heat transfer under laminar flow conditions was investigated experimentally for three types of non-Newtonian nanofluids in a circular tube with constant wall temperature. CMC solution was used as the base fluid and γ-Al2O3, TiO2 and CuO nanoparticles were homogeneously dispersed to create nanodispersions of different concentrations. Nanofluids as well as the base fluid show shear thinning (pseudoplastic) rheological behavior. Results show that the presence of nanoparticles increases the convective heat transfer of the nanodispersions in comparison with the base fluid. The convective heat transfer enhancement is more significant when both the Peclet number and the nanoparticle concentration are increased. The increase in convective heat transfer is higher than the increase caused by the augmentation of the effective thermal conductivity.

Microbial adhesion on novel yttria-stabilized tetragonal zirconia (Y-TZP) implant surfaces with nitrogen-doped hydrogenated amorphous carbon (a-C:H:N) coatings.

PubMed

Schienle, Stefanie; Al-Ahmad, Ali; Kohal, Ralf Joachim; Bernsmann, Falk; Adolfsson, Erik; Montanaro, Laura; Palmero, Paola; Fürderer, Tobias; Chevalier, Jérôme; Hellwig, Elmar; Karygianni, Lamprini

2016-09-01

Biomaterial surfaces are at high risk for initial microbial colonization, persistence, and concomitant infection. The rationale of this study was to assess the initial adhesion on novel implant surfaces of Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans upon incubation. The tested samples were 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) samples with nitrogen-doped hydrogenated amorphous carbon (a-C:H:N) coating (A) and 3Y-TZP samples coated with ceria-stabilized zirconia-based (Ce-TZP) composite and a-C:H:N (B). Uncoated 3Y-TZP samples (C) and bovine enamel slabs (BES) served as controls. Once the surface was characterized, the adherent microorganisms were quantified by estimating the colony-forming units (CFUs). Microbial vitality was assessed by live/dead staining, and microbial-biomaterial surface topography was visualized by scanning electron microscopy (SEM). Overall, A and B presented the lowest CFU values for all microorganisms, while C sheltered significantly less E. faecalis, P. aeruginosa, and C. albicans than BES. Compared to the controls, B demonstrated the lowest vitality values for E. coli (54.12 %) and C. albicans (67.99 %). Interestingly, A (29.24 %) exhibited higher eradication rates for S. aureus than B (13.95 %). Within the limitations of this study, a-C:H:N-coated 3Y-TZP surfaces tended to harbor less initially adherent microorganisms and selectively interfered with their vitality. This could enable further investigation of the new multi-functional zirconia surfaces to confirm their favorable antimicrobial properties in vivo.

Movement of particles using sequentially activated dielectrophoretic particle trapping

DOEpatents

Miles, Robin R.

2004-02-03

Manipulation of DNA and cells/spores using dielectrophoretic (DEP) forces to perform sample preparation protocols for polymerized chain reaction (PCR) based assays for various applications. This is accomplished by movement of particles using sequentially activated dielectrophoretic particle trapping. DEP forces induce a dipole in particles, and these particles can be trapped in non-uniform fields. The particles can be trapped in the high field strength region of one set of electrodes. By switching off this field and switching on an adjacent electrodes, particles can be moved down a channel with little or no flow.

Single-particle characterization of ice-nucleating particles and ice particle residuals sampled by three different techniques

NASA Astrophysics Data System (ADS)

Worringen, A.; Kandler, K.; Benker, N.; Dirsch, T.; Weinbruch, S.; Mertes, S.; Schenk, L.; Kästner, U.; Frank, F.; Nillius, B.; Bundke, U.; Rose, D.; Curtius, J.; Kupiszewski, P.; Weingartner, E.; Schneider, J.; Schmidt, S.; Ebert, M.

2014-09-01

In the present work, three different techniques are used to separate ice-nucleating particles (INP) and ice particle residuals (IPR) from non-ice-active particles: the Ice Selective Inlet (ISI) and the Ice Counterflow Virtual Impactor (Ice-CVI), which sample ice particles from mixed phase clouds and allow for the analysis of the residuals, as well as the combination of the Fast Ice Nucleus Chamber (FINCH) and the Ice Nuclei Pumped Virtual Impactor (IN-PCVI), which provides ice-activating conditions to aerosol particles and extracts the activated ones for analysis. The collected particles were analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis to determine their size, chemical composition and mixing state. Samples were taken during January/February 2013 at the High Alpine Research Station Jungfraujoch. All INP/IPR-separating techniques had considerable abundances (median 20-70%) of contamination artifacts (ISI: Si-O spheres, probably calibration aerosol; Ice-CVI: Al-O particles; FINCH + IN-PCVI: steel particles). Also, potential measurement artifacts (soluble material) occurred (median abundance < 20%). After removal of the contamination particles, silicates and Ca-rich particles, carbonaceous material and metal oxides were the major INP/IPR particle types separated by all three techniques. Minor types include soot and Pb-bearing particles. Sea-salt and sulfates were identified by all three methods as INP/IPR. Lead was identified in less than 10% of the INP/IPR. It was mainly present as an internal mixture with other particle types, but also external lead-rich particles were found. Most samples showed a maximum of the INP/IPR size distribution at 400 nm geometric diameter. In a few cases, a second super-micron maximum was identified. Soot/carbonaceous material and metal oxides were present mainly in the submicron range. ISI and FINCH yielded silicates and Ca-rich particles mainly with diameters above 1 μm, while the Ice-CVI also

Formulation and stabilization of nano-/microdispersion systems using naturally occurring edible polyelectrolytes by electrostatic deposition and complexation.

PubMed

Kuroiwa, Takashi; Kobayashi, Isao; Chuah, Ai Mey; Nakajima, Mitsutoshi; Ichikawa, Sosaku

2015-12-01

This review paper presents an overview of the formulation and functionalization of nano-/microdispersion systems composed of edible materials. We first summarized general aspects on the stability of colloidal systems and the roles of natural polyelectrolytes such as proteins and ionic polysaccharides for the formation and stabilization of colloidal systems. Then we introduced our research topics on (1) stabilization of emulsions by the electrostatic deposition using natural polyelectrolytes and (2) formulation of stable nanodispersion systems by complexation of natural polyelectrolytes. In both cases, the preparation procedures were relatively simple, without high energy input or harmful chemical addition. The properties of the nano-/microdispersion systems, such as particle size, surface charge and dispersion stability were significantly affected by the concerned materials and preparation conditions, including the type and concentration of used natural polyelectrolytes. These dispersion systems would be useful for developing novel foods having high functionality and good stability. Copyright © 2015 Elsevier B.V. All rights reserved.

Thymol nanoencapsulated by sodium caseinate: physical and antilisterial properties.

PubMed

Pan, Kang; Chen, Huaiqiong; Davidson, P Michael; Zhong, Qixin

2014-02-19

In this work, thymol was encapsulated in sodium caseinate using high shear homogenization. The transparent dispersion at neutral pH was stable for 30 days at room temperature as determined by dynamic light scattering and atomic force microscopy, which agreed with high ζ potential of nanoparticles. The slightly decreased particle dimension during storage indicates the absence of Ostwald ripening. When molecular binding was studied by fluorescence spectroscopy, thymol was observed to bind with tyrosine and possibly other amino acid residues away from tryptophan of caseins. At pH 4.6 (isoelectric point of caseins), the stabilization of thymol nanoparticles against aggregation was enabled by soluble soybean polysaccharide, resulting from the combined electrostatic and steric repulsions. The encapsulated thymol showed the significantly improved antilisterial activity in milk with different fat levels when compared to thymol crystals, resulting from the quicker mixing and increased solubility in the milk serum. The transparent thymol nanodispersions have promising applications to improve microbiological safety and quality of foods.

Particle dynamics and particle-cell interaction in microfluidic systems

NASA Astrophysics Data System (ADS)

Stamm, Matthew T.

Particle-laden flow in a microchannel resulting in aggregation of microparticles was investigated to determine the dependence of the cluster growth rate on the following parameters: suspension void fraction, shear strain rate, and channel-height to particle-diameter ratio. The growth rate of an average cluster was found to increase linearly with suspension void fraction, and to obey a power-law relationships with shear strain rate as S 0.9 and channel-height to particle-diameter ratio as (h/d )--3.5. Ceramic liposomal nanoparticles and silica microparticles were functionalized with antibodies that act as targeting ligands. The bio-functionality and physical integrity of the cerasomes were characterized. Surface functionalization allows cerasomes to deliver drugs with selectivity and specificity that is not possible using standard liposomes. The functionalized particle-target cell binding process was characterized using BT-20 breast cancer cells. Two microfluidic systems were used; one with both species in suspension, the other with cells immobilized inside a microchannel and particle suspension as the mobile phase. Effects of incubation time, particle concentration, and shear strain rate on particle-cell binding were investigated. With both species in suspension, the particle-cell binding process was found to be reasonably well-described by a first-order model. Particle desorption and cellular loss of binding affinity in time were found to be negligible; cell-particle-cell interaction was identified as the limiting mechanism in particle-cell binding. Findings suggest that separation of a bound particle from a cell may be detrimental to cellular binding affinity. Cell-particle-cell interactions were prevented by immobilizing cells inside a microchannel. The initial stage of particle-cell binding was investigated and was again found to be reasonably well-described by a first-order model. For both systems, the time constant was found to be inversely proportional to

Particle preconcentrator

DOEpatents

Linker, Kevin L.; Conrad, Frank J.; Custer, Chad A.; Rhykerd, Jr., Charles L.

1998-01-01

An apparatus and method for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents.

Particle preconcentrator

DOEpatents

Linker, Kevin L.; Conrad, Frank J.; Custer, Chad A.; Rhykerd, Jr., Charles L.

2005-09-20

An apparatus and method for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents.

Particle preconcentrator

DOEpatents

Linker, Kevin L.; Conrad, Frank J.; Custer, Chad A.; Rhykerd, Jr., Charles L.

2000-01-01

An apparatus and method for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents.

Particle preconcentrator

DOEpatents

Linker, K.L.; Conrad, F.J.; Custer, C.A.; Rhykerd, C.L. Jr.

1998-12-29

An apparatus and method are disclosed for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents. 3 figs.

Bulk and Interface Thermodynamics of Calcia-, and Yttria-doped Zirconia Ceramics: Nanograined Phase Stability

NASA Astrophysics Data System (ADS)

Drazin, John Walter

Calcia-, and yttria- doped zirconia powders and samples are essential systems in academia and industry due to their observed bulk polymorphism. Pure zirconia manifests as Baddeleyite, a monoclinic structured mineral with 7-fold coordination. This bulk form of zirconia has little application due to its asymmetry. Therefore dopants are added to the grain in-order to induce phase transitions to either a tetragonal or cubic polymorph with the incorporation of oxygen vacancies due to the dopant charge mis-match with the zirconia matrix. The cubic polymorph has cubic symmetry such that these samples see applications in solid oxide fuel cells (SOFCs) due to the high oxygen vacancy concentrations and high ionic mobility at elevated temperatures. The tetragonal polymorph has slight asymmetry in the c-axis compared to the a-axis such that the tetragonal samples have increased fracture toughness due to an impact induced phase transformation to a cubic structure. These ceramic systems have been extensively studied in academia and used in various industries, but with the advent of nanotechnology one can wonder whether smaller grain samples will see improved characteristics similar to their bulk grain counterparts. However, there is a lack of data and knowledge of these systems in the nano grained region which provides us with an opportunity to advance the theory in these systems. The polymorphism seen in the bulk grains samples is also seen in the nano-grained samples, but at slightly distinct dopant concentrations. The current theory hypothesizes that a surface excess, gamma (J/m 2), can be added to the Gibbs Free energy equation to account for the additional free energy of the nano-grain atoms. However, these surface energies have been difficult to measure and therefore thermodynamic data on these nano-grained samples have been sparse. Therefore, in this work, I will use a well established water adsorption microcalorimetry apparatus to measure the water coverage isotherms

Tumbling in Turbulence: How much does particle shape effect particle motion?

NASA Astrophysics Data System (ADS)

Variano, E. A.; Andersson, H. I.; Zhao, L.; Byron, M.

2014-12-01

Natural particles suspended in surface water are often non-spherical. We explore the ways in which particle shape effects particle motion, focusing specifically on how particle rotation is divided into spinning and tumbling components. This, in turn, will effect particle collision, clustering, and settling rates. We focus on idealized axisymmetric particles shaped as rods, discs, and spheroids. They are chosen so as to explain the physics of aspherical-particle motion that will be relevant for natural particles such as plankton, sediment, or aggregates (e.g. oil-mineral aggregates, clay flocs, or bio-sediment aggregates held together by TEP). Our work begins with laboratory measurements of particle motion in a turbulence tank built to mimic the flow found in rivers, estuaries, and the ocean surface mixed layer. We then proceed to direct numerical simulation of particle-flow interactions in sheared turbulence similar to that which is found in the surface water of creeks and rivers. We find that shape has only a very weak effect on particle angular velocity, which is a quantity calculated with respect the global reference frame (i.e. east/north/up). If we analyze rotation in a particle's local frame (i.e. the particle's principle axes of rotation), then particle shape has a strong effect on rotation. In the local frame, rotation is described by two components: tumbling and spinning. We find that rod-shaped particles spin more than they tumble, and we find that disc-shaped particles tumble more than they spin. Such behavior is indicative of how particles respond the the directional influence of vortex tubes in turbulence, and such response has implications for particle motion other than rotation. Understanding particle alignment is relevant for predicting particle-particle collision rates, particle-wall collision rates, and the shear-driven breakup of aggregates. We discuss these briefly in the context of what can be concluded from the rotation data discussed above.

Effect of Particle Morphology on the Reactivity of Explosively Dispersed Titanium Particles

NASA Astrophysics Data System (ADS)

Frost, David; Cairns, Malcolm; Goroshin, Samuel; Zhang, Fan

2009-06-01

The effect of particle morphology on the reaction of titanium (Ti) particles explosively dispersed during the detonation of either cylindrical or spherical charges has been investigated experimentally. The explosive charges consisted of packed beds of Ti particles saturated with nitromethane. The reaction behavior of irregularly-shaped Ti particles in three size ranges is compared with tests with spherical Ti particles. The particle reaction is strongly dependent on particle morphology, e.g., 95 μm spherical Ti particles failed to ignite (in cylinders up to 49 mm in dia), whereas similarly sized irregular Ti particles readily ignited. For irregular particles, the uniformity of ignition on the particle cloud surface was almost independent of particle size, but depended on charge diameter. As the charge diameter was reduced, ignition in the conically expanding particle cloud occurred only at isolated spots or bands. For spherical charges, although large irregular Ti particles ignited promptly and uniformly throughout the particle cloud, the smallest particles dispersed nonuniformly and ignition occurred at isolated locations. In general, particle ignition is a competition between particle heating (which is influenced by particle morphology, size, number density and the local thermodynamic history) and expansion cooling of the products.

Parallel particle impactor - novel size-selective particle sampler for accurate fractioning of inhalable particles

NASA Astrophysics Data System (ADS)

Trakumas, S.; Salter, E.

2009-02-01

Adverse health effects due to exposure to airborne particles are associated with particle deposition within the human respiratory tract. Particle size, shape, chemical composition, and the individual physiological characteristics of each person determine to what depth inhaled particles may penetrate and deposit within the respiratory tract. Various particle inertial classification devices are available to fractionate airborne particles according to their aerodynamic size to approximate particle penetration through the human respiratory tract. Cyclones are most often used to sample thoracic or respirable fractions of inhaled particles. Extensive studies of different cyclonic samplers have shown, however, that the sampling characteristics of cyclones do not follow the entire selected convention accurately. In the search for a more accurate way to assess worker exposure to different fractions of inhaled dust, a novel sampler comprising several inertial impactors arranged in parallel was designed and tested. The new design includes a number of separated impactors arranged in parallel. Prototypes of respirable and thoracic samplers each comprising four impactors arranged in parallel were manufactured and tested. Results indicated that the prototype samplers followed closely the penetration characteristics for which they were designed. The new samplers were found to perform similarly for liquid and solid test particles; penetration characteristics remained unchanged even after prolonged exposure to coal mine dust at high concentration. The new parallel impactor design can be applied to approximate any monotonically decreasing penetration curve at a selected flow rate. Personal-size samplers that operate at a few L/min as well as area samplers that operate at higher flow rates can be made based on the suggested design. Performance of such samplers can be predicted with high accuracy employing well-established impaction theory.

Particle astrophysics

NASA Technical Reports Server (NTRS)

Sadoulet, Bernard; Cronin, James; Aprile, Elena; Barish, Barry C.; Beier, Eugene W.; Brandenberger, Robert; Cabrera, Blas; Caldwell, David; Cassiday, George; Cline, David B.

1991-01-01

The following scientific areas are reviewed: (1) cosmology and particle physics (particle physics and the early universe, dark matter, and other relics); (2) stellar physics and particles (solar neutrinos, supernovae, and unconventional particle physics); (3) high energy gamma ray and neutrino astronomy; (4) cosmic rays (space and ground observations). Highest scientific priorities for the next decade include implementation of the current program, new initiatives, and longer-term programs. Essential technological developments, such as cryogenic detectors of particles, new solar neutrino techniques, and new extensive air shower detectors, are discussed. Also a certain number of institutional issues (the funding of particle astrophysics, recommended funding mechanisms, recommended facilities, international collaborations, and education and technology) which will become critical in the coming decade are presented.

Continuous time random walk with local particle-particle interaction

NASA Astrophysics Data System (ADS)

Xu, Jianping; Jiang, Guancheng

2018-05-01

The continuous time random walk (CTRW) is often applied to the study of particle motion in disordered media. Yet most such applications do not allow for particle-particle (walker-walker) interaction. In this paper, we consider a CTRW with particle-particle interaction; however, for simplicity, we restrain the interaction to be local. The generalized Chapman-Kolmogorov equation is modified by introducing a perturbation function that fluctuates around 1, which models the effect of interaction. Subsequently, a time-fractional nonlinear advection-diffusion equation is derived from this walking system. Under the initial condition of condensed particles at the origin and the free-boundary condition, we numerically solve this equation with both attractive and repulsive particle-particle interactions. Moreover, a Monte Carlo simulation is devised to verify the results of the above numerical work. The equation and the simulation unanimously predict that this walking system converges to the conventional one in the long-time limit. However, for systems where the free-boundary condition and long-time limit are not simultaneously satisfied, this convergence does not hold.

Particle capture device

DOEpatents

Jayne, John T.; Worsnop, Douglas R.

2016-02-23

In example embodiments, particle collection efficiency in aerosol analyzers and other particle measuring instruments is improved by a particle capture device that employs multiple collisions to decrease momentum of particles until the particles are collected (e.g., vaporized or come to rest). The particle collection device includes an aperture through which a focused particle beam enters. A collection enclosure is coupled to the aperture and has one or more internal surfaces against which particles of the focused beam collide. One or more features are employed in the collection enclosure to promote particles to collide multiple times within the enclosure, and thereby be vaporized or come to rest, rather than escape through the aperture.

Zircon-Based Ceramics Composite Coating for Environmental Barrier Coating

NASA Astrophysics Data System (ADS)

Suzuki, M.; Sodeoka, S.; Inoue, T.

2008-09-01

Studies on plasma spraying of zircon (ZrSiO4) have been carried out by the authors as one of the candidates for an environmental barrier coating (EBC) application, and had reported that substrate temperature is one of the most important factors to obtain crack-free and highly adhesive coating. In this study, several amounts of yttria were added to zircon powder, and the effect of the yttria addition on the structure and properties of the coatings were evaluated to improve the stability of the zircon coating structure at elevated temperature. The coatings obtained were composed of yttria-stabilized zirconia (YSZ), glassy silica, whereas the one prepared from monolithic zircon powder was composed of the metastable high temperature tetragonal phase of zirconia and glassy silica. After the heat treatment over 1200 °C, silica and zirconia formed zircon in all coatings. However, coatings with higher amounts of yttria exhibited lower amounts of zircon. This resulted in the less open porosity of the coating at elevated temperature. These yttria-added coatings also showed good adhesion even after the heat treatment, while monolithic zircon coating pealed off.

Composite Gypsum Binders with Silica-containing Additives

NASA Astrophysics Data System (ADS)

Chernysheva, N. V.; Lesovik, V. S.; Drebezgova, M. Yu; Shatalova, S. V.; Alaskhanov, A. H.

2018-03-01

New types of fine mineral additives are proposed for designing water-resistant Composite Gypsum Binders (CGB); these additives significantly differ from traditional quartz feed: wastes from wet magnetic separation of Banded Iron Formation (BIF WMS waste), nanodispersed silica powder (NSP), chalk. Possibility of their combined use has been studied as well.

Method for coating ultrafine particles, system for coating ultrafine particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jie; Liu, Yung

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 particlesmore » with a coating moiety.« less

Effect of Particle Morphology on the Reactivity of Explosively Dispersed Titanium Particles

NASA Astrophysics Data System (ADS)

Frost, David L.; Cairns, Malcolm; Goroshin, Samuel; Zhang, Fan

2009-12-01

The effect of particle morphology on the reaction of titanium (Ti) particles explosively dispersed during the detonation of either cylindrical or spherical charges has been investigated experimentally. The explosive charges consisted of packed beds of Ti particles saturated with nitromethane. The reaction behaviour of irregularly-shaped Ti particles in three size ranges is compared with tests with spherical Ti particles. The particle reaction is strongly dependent on particle morphology, e.g., 95 μm spherical Ti particles failed to ignite (in cylinders up to 49 mm in dia), whereas similarly sized irregular Ti particles readily ignited. For irregular particles, the uniformity of ignition on the particle cloud surface was almost independent of particle size, but depended on charge diameter. As the charge diameter was reduced, ignition in the conically expanding particle cloud occurred only at isolated spots or bands. For spherical charges, whereas large irregular Ti particles ignited promptly and uniformly throughout the particle cloud, the smallest particles dispersed nonuniformly and ignition occurred at isolated locations after a delay. Hence the charge geometry, as well as particle morphology, influences the reaction behaviour of the particles.

Evaluation of laser bacterial anti-fouling of transparent nanocrystalline yttria-stabilized-zirconia cranial implant.

PubMed

Damestani, Yasaman; De Howitt, Natalie; Halaney, David L; Garay, Javier E; Aguilar, Guillermo

2016-10-01

The development and feasibility of a novel nanocrystalline yttria-stabilized-zirconia (nc-YSZ) cranial implant has been recently established. The purpose of what we now call "window to the brain (WttB)" implant (or platform), is to improve patient care by providing a technique for delivery and/or collection of light into/from the brain, on demand, over large areas, and on a chronically recurring basis without the need for repeated craniotomies. WttB holds the transformative potential for enhancing light-based diagnosis and treatment of a wide variety of brain pathologies including cerebral edema, traumatic brain injury, stroke, glioma, and neurodegenerative diseases. However, bacterial adhesion to the cranial implant is the leading factor for biofilm formation (fouling), infection, and treatment failure. Escherichia coli (E. coli), in particular, is the most common isolate in gram-negative bacillary meningitis after cranial surgery or trauma. The transparency of our WttB implant may provide a unique opportunity for non-invasive treatment of bacterial infection under the implant using medical lasers. A drop of a diluted overnight culture of BL21-293 E. coli expressing luciferase was seeded between the nc-YSZ implant and the agar plate. This was followed by immediate irradiation with selected laser. After each laser treatment the nc-YSZ was removed, and cultures were incubated for 24 hours at 37 °C. The study examined continuous wave (CW) and pulsed wave (PW) modes of near-infrared (NIR) 810 nm laser wavelength with a power output ranging from 1 to 3 W. During irradiation, the temperature distribution of nc-YSZ surface was monitored using an infrared thermal camera. Relative luminescence unit (RLU) was used to evaluate the viability of bacteria after the NIR laser treatment. Analysis of RLU suggests that the viability of E. coli biofilm formation was reduced with NIR laser treatment when compared to the control group (P < 0.01) and loss of viability

Particle Detectors

NASA Astrophysics Data System (ADS)

Grupen, Claus; Shwartz, Boris

2011-09-01

Preface to the first edition; Preface to the second edition; Introduction; 1. Interactions of particles and radiation with matter; 2. Characteristic properties of detectors; 3. Units of radiation measurements and radiation sources; 4. Accelerators; 5. Main physical phenomena used for particle detection and basic counter types; 6. Historical track detectors; 7. Track detectors; 8. Calorimetry; 9. Particle identification; 10. Neutrino detectors; 11. Momentum measurement and muon detection; 12. Ageing and radiation effects; 13. Example of a general-purpose detector: Belle; 14. Electronics; 15. Data analysis; 16. Applications of particle detectors outside particle physics; 17. Glossary; 18. Solutions; 19. Resumé; Appendixes; Index.

Single-particle characterization of ice-nucleating particles and ice particle residuals sampled by three different techniques

NASA Astrophysics Data System (ADS)

Worringen, A.; Kandler, K.; Benker, N.; Dirsch, T.; Mertes, S.; Schenk, L.; Kästner, U.; Frank, F.; Nillius, B.; Bundke, U.; Rose, D.; Curtius, J.; Kupiszewski, P.; Weingartner, E.; Vochezer, P.; Schneider, J.; Schmidt, S.; Weinbruch, S.; Ebert, M.

2015-04-01

In the present work, three different techniques to separate ice-nucleating particles (INPs) as well as ice particle residuals (IPRs) from non-ice-active particles are compared. The Ice Selective Inlet (ISI) and the Ice Counterflow Virtual Impactor (Ice-CVI) sample ice particles from mixed-phase clouds and allow after evaporation in the instrument for the analysis of the residuals. The Fast Ice Nucleus Chamber (FINCH) coupled with the Ice Nuclei Pumped Counterflow Virtual Impactor (IN-PCVI) provides ice-activating conditions to aerosol particles and extracts the activated particles for analysis. The instruments were run during a joint field campaign which took place in January and February 2013 at the High Alpine Research Station Jungfraujoch (Switzerland). INPs and IPRs were analyzed offline by scanning electron microscopy and energy-dispersive X-ray microanalysis to determine their size, chemical composition and mixing state. Online analysis of the size and chemical composition of INP activated in FINCH was performed by laser ablation mass spectrometry. With all three INP/IPR separation techniques high abundances (median 20-70%) of instrumental contamination artifacts were observed (ISI: Si-O spheres, probably calibration aerosol; Ice-CVI: Al-O particles; FINCH + IN-PCVI: steel particles). After removal of the instrumental contamination particles, silicates, Ca-rich particles, carbonaceous material and metal oxides were the major INP/IPR particle types obtained by all three techniques. In addition, considerable amounts (median abundance mostly a few percent) of soluble material (e.g., sea salt, sulfates) were observed. As these soluble particles are often not expected to act as INP/IPR, we consider them as potential measurement artifacts. Minor types of INP/IPR include soot and Pb-bearing particles. The Pb-bearing particles are mainly present as an internal mixture with other particle types. Most samples showed a maximum of the INP/IPR size distribution at 200

Apparatus for separating particles utilizing engineered acoustic contrast capture particles

DOEpatents

Kaduchak, Gregory; Ward, Michael D

2014-10-21

An apparatus for separating particles from a medium includes a capillary defining a flow path therein that is in fluid communication with a medium source. The medium source includes engineered acoustic contrast capture particle having a predetermined acoustic contrast. The apparatus includes a vibration generator that is operable to produce at least one acoustic field within the flow path. The acoustic field produces a force potential minima for positive acoustic contrast particles and a force potential minima for negative acoustic contrast particles in the flow path and drives the engineered acoustic contrast capture particles to either the force potential minima for positive acoustic contrast particles or the force potential minima for negative acoustic contrast particles.

Apparatus for separating particles utilizing engineered acoustic contrast capture particles

DOEpatents

Kaduchak, Gregory [Los Alamos, NM; Ward, Michael D [Los Alamos, NM

2011-12-27

An apparatus for separating particles from a medium includes a capillary defining a flow path therein that is in fluid communication with a medium source. The medium source includes engineered acoustic contrast capture particle having a predetermined acoustic contrast. The apparatus includes a vibration generator that is operable to produce at least one acoustic field within the flow path. The acoustic field produces a force potential minima for positive acoustic contrast particles and a force potential minima for negative acoustic contrast particles in the flow path and drives the engineered acoustic contrast capture particles to either the force potential minima for positive acoustic contrast particles or the force potential minima for negative acoustic contrast particles.

Particle nonuniformity effects on particle cloud flames in low gravity

NASA Technical Reports Server (NTRS)

Berlad, A. L.; Tangirala, V.; Seshadri, K.; Facca, L. T.; Ogrin, J.; Ross, H.

1991-01-01

Experimental and analytical studies of particle cloud combustion at reduced gravity reveal the substantial roles that particle cloud nonuniformities may play in particle cloud combustion. Macroscopically uniform, quiescent particle cloud systems (at very low gravitational levels and above) sustain processes which can render them nonuniform on both macroscopic and microscopic scales. It is found that a given macroscopically uniform, quiescent particle cloud flame system can display a range of microscopically nonuniform features which lead to a range of combustion features. Microscopically nonuniform particle cloud distributions are difficult experimentally to detect and characterize. A uniformly distributed lycopodium cloud of particle-enriched microscopic nonuniformities in reduced gravity displays a range of burning velocities for any given overall stoichiometry. The range of observed and calculated burning velocities corresponds to the range of particle enriched concentrations within a characteristic microscopic nonuniformity. Sedimentation effects (even in reduced gravity) are also examined.

Structurally coloured secondary particles composed of black and white colloidal particles.

PubMed

Takeoka, Yukikazu; Yoshioka, Shinya; Teshima, Midori; Takano, Atsushi; Harun-Ur-Rashid, Mohammad; Seki, Takahiro

2013-01-01

This study investigated the colourful secondary particles formed by controlling the aggregation states of colloidal silica particles and the enhancement of the structural colouration of the secondary particles caused by adding black particles. We obtained glossy, partially structurally coloured secondary particles in the absence of NaCl, but matte, whitish secondary particles were obtained in the presence of NaCl. When a small amount of carbon black was incorporated into both types of secondary particles, the incoherent multiple scattering of light from the amorphous region was considerably reduced. However, the peak intensities in the reflection spectra, caused by Bragg reflection and by coherent single wavelength scattering, were only slightly decreased. Consequently, a brighter structural colour of these secondary particles was observed with the naked eye. Furthermore, when magnetite was added as a black particle, the coloured secondary particles could be moved and collected by applying an external magnetic field.

Structurally Coloured Secondary Particles Composed of Black and White Colloidal Particles

PubMed Central

Takeoka, Yukikazu; Yoshioka, Shinya; Teshima, Midori; Takano, Atsushi; Harun-Ur-Rashid, Mohammad; Seki, Takahiro

2013-01-01

This study investigated the colourful secondary particles formed by controlling the aggregation states of colloidal silica particles and the enhancement of the structural colouration of the secondary particles caused by adding black particles. We obtained glossy, partially structurally coloured secondary particles in the absence of NaCl, but matte, whitish secondary particles were obtained in the presence of NaCl. When a small amount of carbon black was incorporated into both types of secondary particles, the incoherent multiple scattering of light from the amorphous region was considerably reduced. However, the peak intensities in the reflection spectra, caused by Bragg reflection and by coherent single wavelength scattering, were only slightly decreased. Consequently, a brighter structural colour of these secondary particles was observed with the naked eye. Furthermore, when magnetite was added as a black particle, the coloured secondary particles could be moved and collected by applying an external magnetic field. PMID:23917891

Apparatus for separating particles utilizing engineered acoustic contrast capture particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaduchak, Gregory; Ward, Michael D

An apparatus for separating particles from a medium includes a capillary defining a flow path therein that is in fluid communication with a medium source. The medium source includes engineered acoustic contrast capture particle having a predetermined acoustic contrast. The apparatus includes a vibration generator that is operable to produce at least one acoustic field within the flow path. The acoustic field produces a force potential minima for positive acoustic contrast particles and a force potential minima for negative acoustic contrast particles in the flow path and drives the engineered acoustic contrast capture particles to either the force potential minimamore » for positive acoustic contrast particles or the force potential minima for negative acoustic contrast particles.« less

Effect of synthesis process on the microstructure and electrical conductivity of nickel/yttria-stabilized zirconia powders prepared by urea hydrolysis

NASA Astrophysics Data System (ADS)

Lin, Jyung-Dong; Wu, Zhao-Lun

In this study, NiO/YSZ composite powders were synthesized using hydrolysis on two solutions, one contains YSZ particles and Ni 2+ ion, and the other contains NiO particles, Zr 4+, and Y 3+ ions, with the aid of urea. The microstructure of the powders and sintered bulks was further characterized using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicated that various synthesis processes yielded NiO/YSZ powders with different morphologies. The NiO precursors would deposit onto the surface of YSZ particles, and NiO-deposited YSZ composite powders were obtained. Alternatively, it was not observed that YSZ precursors deposited onto the surface of NiO particles, thus, a uniform powder mixture of fine NiO and fine YSZ particles was produced. After sintering and subsequent reduction, these powders would lead to the variations of Ni distribution in the YSZ matrix and conductivity of cermets. Owing to the core-shell structure of the powders and the higher size ratio of YSZ and NiO particles, the conductivity of cermet with NiO-deposited YSZ powders containing 23 wt% NiO is comparable to those with a NiO/YSZ powder mixture containing 50 wt% NiO.

Effects of Dopant Metal Variation and Material Synthesis Method on the Material Properties of Mixed Metal Ferrites in Yttria Stabilized Zirconia for Solar Thermochemical Fuel Production

DOE PAGES

Leonard, Jeffrey; Reyes, Nichole; Allen, Kyle M.; ...

2015-01-01

Mixed metal ferrites have shown much promise in two-step solar-thermochemical fuel production. Previous work has typically focused on evaluating a particular metal ferrite produced by a particular synthesis process, which makes comparisons between studies performed by independent researchers difficult. A comparative study was undertaken to explore the effects different synthesis methods have on the performance of a particular material during redox cycling using thermogravimetry. This study revealed that materials made via wet chemistry methods and extended periods of high temperature calcination yield better redox performance. Differences in redox performance between materials made via wet chemistry methods were minimal and thesemore » demonstrated much better performance than those synthesized via the solid state method. Subsequently, various metal ferrite samples (NiFe 2 O 4 , MgFe 2 O 4 , CoFe 2 O 4 , and MnFe 2 O 4 ) in yttria stabilized zirconia (8YSZ) were synthesized via coprecipitation and tested to determine the most promising metal ferrite combination. It was determined that 10 wt.% CoFe 2 O 4 in 8YSZ produced the highest and most consistent yields of O 2 and CO. By testing the effects of synthesis methods and dopants in a consistent fashion, those aspects of ferrite preparation which are most significant can be revealed. More importantly, these insights can guide future efforts in developing the next generation of thermochemical fuel production materials.« less

In Situ FT-IR Spectroscopic Study of CO2 and CO Adsorption on Y2O3, ZrO2, and Yttria-Stabilized ZrO2

PubMed Central

2013-01-01

In situ FT-IR spectroscopy was exploited to study the adsorption of CO2 and CO on commercially available yttria-stabilized ZrO2 (8 mol % Y, YSZ-8), Y2O3, and ZrO2. All three oxides were pretreated at high temperatures (1173 K) in air, which leads to effective dehydroxylation of pure ZrO2. Both Y2O3 and YSZ-8 show a much higher reactivity toward CO and CO2 adsorption than ZrO2 because of more facile rehydroxylation of Y-containing phases. Several different carbonate species have been observed following CO2 adsorption on Y2O3 and YSZ-8, which are much more strongly bound on the former, due to formation of higher-coordinated polydentate carbonate species upon annealing. As the crucial factor governing the formation of carbonates, the presence of reactive (basic) surface hydroxyl groups on Y-centers was identified. Therefore, chemisorption of CO2 most likely includes insertion of the CO2 molecule into a reactive surface hydroxyl group and the subsequent formation of a bicarbonate species. Formate formation following CO adsorption has been observed on all three oxides but is less pronounced on ZrO2 due to effective dehydroxylation of the surface during high-temperature treatment. The latter generally causes suppression of the surface reactivity of ZrO2 samples regarding reactions involving CO or CO2 as reaction intermediates. PMID:24009780

Single-particle characterization of ice-nucleating particles and ice particles residuals sampled by three different techniques

NASA Astrophysics Data System (ADS)

Kandler, Konrad; Worringen, Annette; Benker, Nathalie; Dirsch, Thomas; Mertes, Stephan; Schenk, Ludwig; Kästner, Udo; Frank, Fabian; Nillius, Björn; Bundke, Ulrich; Rose, Diana; Curtius, Joachim; Kupiszewski, Piotr; Weingartner, Ernest; Vochezer, Paul; Schneider, Johannes; Schmidt, Susan; Weinbruch, Stephan; Ebert, Martin

2015-04-01

During January/February 2013, at the High Alpine Research Station Jungfraujoch a measurement campaign was carried out, which was centered on atmospheric ice-nucleating particles (INP) and ice particle residuals (IPR). Three different techniques for separation of INP and IPR from the non-ice-active particles are compared. The Ice Selective Inlet (ISI) and the Ice Counterflow Virtual Impactor (Ice-CVI) sample ice particles from mixed phase clouds and allow for the analysis of the residuals. The combination of the Fast Ice Nucleus Chamber (FINCH) and the Ice Nuclei Pumped Counterflow Virtual Impactor (IN-PCVI) provides ice-activating conditions to aerosol particles and extracts the activated INP for analysis. Collected particles were analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis to determine size, chemical composition and mixing state. All INP/IPR-separating techniques had considerable abundances (median 20 - 70 %) of instrumental contamination artifacts (ISI: Si-O spheres, probably calibration aerosol; Ice-CVI: Al-O particles; FINCH+IN-PCVI: steel particles). Also, potential sampling artifacts (e.g., pure soluble material) occurred with a median abundance of < 20 %. While these could be explained as IPR by ice break-up, for INP their IN-ability pathway is less clear. After removal of the contamination artifacts, silicates and Ca-rich particles, carbonaceous material and metal oxides were the major INP/IPR particle types separated by all three techniques. Soot was a minor contributor. Lead was detected in less than 10 % of the particles, of which the majority were internal mixtures with other particle types. Sea-salt and sulfates were identified by all three methods as INP/IPR. Most samples showed a maximum of the INP/IPR size distribution at 400 nm geometric diameter. In a few cases, a second super-micron maximum was identified. Soot/carbonaceous material and metal oxides were present mainly in the submicron range. ISI and FINCH

Particle separator

DOEpatents

Hendricks, Charles D.

1990-01-01

Method and apparatus (10) are provided for separating and classifying particles (48,50,56) by dispersing the particles within a fluid (52) that is upwardly flowing within a cone-shaped pipe (12) that has its large end (20) above its small end (18). Particles of similar size and shape (48,50) migrate to individual levels (A,B) within the flowing fluid. As the fluid is deflected by a plate (42) at the top end of the pipe (12), the smallest particles are collected on a shelf-like flange (40). Ever larger particles are collected as the flow rate of the fluid is increased. To prevent particle sticking on the walls (14) of the pipe (12), additional fluid is caused to flow into the pipe (12) through holes (68) that are specifically provided for that purpose. Sticking is further prevented by high frequency vibrators (70) that are positioned on the apparatus (10).

Laser particle sorter

DOEpatents

Martin, John C.; Buican, Tudor N.

1989-01-01

Method and apparatus for sorting particles, such as biological particles. A first laser defines an optical path having an intensity gradient which is effective to propel the particles along the path but which is sufficiently weak that the particles are not trapped in an axial direction. A probe laser beam interrogates the particles to identify predetermined phenotypical characteristics of the particles. A second laser beam intersects the driving first laser beam, wherein the second laser beam is activated by an output signal indicative of a predetermined characteristic. The second laser beam is switchable between a first intensity and a second intensity, where the first intensity is effective to displace selected particles from the driving laser beam and the second intensity is effective to propel selected particles along the deflection laser beam. The selected particles may then be propelled by the deflection beam to a location effective for further analysis.

Particle transport and deposition: basic physics of particle kinetics.

PubMed

Tsuda, Akira; Henry, Frank S; Butler, James P

2013-10-01

The human body interacts with the environment in many different ways. The lungs interact with the external environment through breathing. The enormously large surface area of the lung with its extremely thin air-blood barrier is exposed to particles suspended in the inhaled air. The particle-lung interaction may cause deleterious effects on health if the inhaled pollutant aerosols are toxic. Conversely, this interaction can be beneficial for disease treatment if the inhaled particles are therapeutic aerosolized drugs. In either case, an accurate estimation of dose and sites of deposition in the respiratory tract is fundamental to understanding subsequent biological response, and the basic physics of particle motion and engineering knowledge needed to understand these subjects is the topic of this article. A large portion of this article deals with three fundamental areas necessary to the understanding of particle transport and deposition in the respiratory tract. These are: (i) the physical characteristics of particles, (ii) particle behavior in gas flow, and (iii) gas-flow patterns in the respiratory tract. Other areas, such as particle transport in the developing lung and in the diseased lung are also considered. The article concludes with a summary and a brief discussion of areas of future research. © 2013 American Physiological Society. Compr Physiol 3:1437-1471, 2013.

Particle transport and deposition: basic physics of particle kinetics

PubMed Central

Tsuda, Akira; Henry, Frank S.; Butler, James P.

2015-01-01

The human body interacts with the environment in many different ways. The lungs interact with the external environment through breathing. The enormously large surface area of the lung with its extremely thin air-blood barrier is exposed to particles suspended in the inhaled air. Whereas the particle-lung interaction may cause deleterious effects on health if the inhaled pollutant aerosols are toxic, this interaction can be beneficial for disease treatment if the inhaled particles are therapeutic aerosolized drug. In either case, an accurate estimation of dose and sites of deposition in the respiratory tract is fundamental to understanding subsequent biological response, and the basic physics of particle motion and engineering knowledge needed to understand these subjects is the topic of this chapter. A large portion of this chapter deals with three fundamental areas necessary to the understanding of particle transport and deposition in the respiratory tract. These are: 1) the physical characteristics of particles, 2) particle behavior in gas flow, and 3) gas flow patterns in the respiratory tract. Other areas, such as particle transport in the developing lung and in the diseased lung are also considered. The chapter concludes with a summary and a brief discussion of areas of future research. PMID:24265235

The Effect of Particle Properties on Hot Particle Spot Fire Ignition

NASA Astrophysics Data System (ADS)

Zak, Casey David

The ignition of natural combustible material by hot metal particles is an important fire ignition pathway by which wildland and wildland-urban-interface spot fires are started. There are numerous cases reported of wild fires started by clashing power-lines or from sparks generated by machines or engines. Similarly there are many cases reported of fires caused by grinding, welding and cutting sparks. Up to this point, research on hot particle spot fire ignition has largely focused on particle generation and transport. A small number of studies have examined what occurs after a hot particle contacts a natural fuel bed, but until recently the process remained poorly understood. This work describes an investigation of the effect of particle size, temperature and thermal properties on the ability of hot particles to cause flaming ignition of cellulosic fuel beds. Both experimental and theoretical approaches are used, with a focus on understanding the physics underlying the ignition process. For the experimental study, spheres of stainless steel, aluminum, brass and copper are heated in a tube furnace and dropped onto a powdered cellulose fuel bed; the occurrence of flaming ignition or lack thereof is visually observed and recorded. This procedure is repeated a large number of times for each metal type, varying particle diameter from 2 to 11 mm and particle temperature between 575 and 1100°C. The results of these experiments are statistically analyzed to find approximate ignition boundaries and identify boundary trends with respect to the particle parameters of interest. Schlieren images recorded during the ignition experiments are also used to more accurately describe the ignition process. Based on these images, a simple theoretical model of hot particle spot fire ignition is developed and used to explore the experimental trends further. The model under-predicts the minimum ignition temperatures required for small spheres, but agrees qualitatively with the experimental

Laser particle sorter

DOEpatents

Martin, J.C.; Buican, T.N.

1987-11-30

Method and apparatus are provided for sorting particles, such as biological particles. A first laser is used to define an optical path having an intensity gradient which is effective to propel the particles along the path but which is sufficiently weak that the particles are not trapped in an axial direction. A probe laser beam is provided for interrogating the particles to identify predetermined phenotypical characteristics of the particles. A second laser beam is provided to intersect the driving first laser beam, wherein the second laser beam is activated by an output signal indicative of a predetermined characteristic. The second laser beam is switchable between a first intensity and a second intensity, where the first intensity is effective to displace selected particles from the driving laser beam and the second intensity is effective to propel selected particles along the deflection laser beam. The selected particles may then be propelled by the deflection beam to a location effective for further analysis. 2 figs.

Decoupling the Role of Particle Inertia and Gravity on Particle Dispersion

NASA Technical Reports Server (NTRS)

Squires, Kyle D.

2002-01-01

Particle dispersion and the influence that particle momentum exchange has on the properties of a turbulent carrier flow in micro-gravity environments challenge present understanding and predictive schemes. The objective of this effort has been to develop and assess high-fidelity simulation tools for predicting particle transport within micro-gravity environments suspended in turbulent flows. The computational technique is based on Direct Numerical Simulation (DNS) of the incompressible Navier-Stokes equations. The particular focus of the present work is on the class of dilute flows in which particle volume fractions and inter-particle collisions are negligible. Particle motion is assumed to be governed by drag with particle relaxation times ranging from the Kolmogorov scale to the Eulerian timescale of the turbulence and particle mass loadings up to one. The velocity field was made statistically stationary by forcing the low wavenumbers of the flow. The calculations were performed using 96(exp 3) collocation points and the Taylor-scale Reynolds number for the stationary flow was 62. The effect of particles on the turbulence was included in the Navier-Stokes equations using the point-force approximation in which 96(exp 3) particles were used in the calculations. DNS results show that particles increasingly dissipate fluid kinetic energy with increased loading, with the reduction in kinetic energy being relatively independent of the particle relaxation time. Viscous dissipation in the fluid decreases with increased loading and is larger for particles with smaller relaxation times. Fluid energy spectra show that there is a non-uniform distortion of the turbulence with a relative increase in small-scale energy. The non-uniform distortion significantly affects the transport of the dissipation rate, with the production and destruction of dissipation exhibiting completely different behaviors. The spectrum of the fluid-particle energy exchange rate shows that the fluid

Auroral particles

NASA Technical Reports Server (NTRS)

Evans, David S.

1987-01-01

The problems concerning the aurora posed prior to the war are now either solved in principle or were restated in a more fundamental form. The pre-war hypothesis concerning the nature of the auroral particles and their energies was fully confirmed, with the exception that helium and oxygen ions were identified as participating in the auroral particle precipitation in addition to the protons. The nature of the near-Earth energization processes affecting auroral particles was clarified. Charged particle trajectories in various electric field geometries were modeled. The physical problems have now moved from determining the nature and geometry of the electric fields, which accelerate charged particles near the Earth, to accounting for the existence of these electric fields as a natural consequence of the solar wind's interaction with Earth. Ultimately the reward in continuing the work in auroral and magnetospheric particle dynamics will be a deeper understanding of the subtleties of classical electricity and magnetism as applied to situations not blessed with well-defined and invariant geometries.

Real-time explosive particle detection using a cyclone particle concentrator.

PubMed

Hashimoto, Yuichiro; Nagano, Hisashi; Takada, Yasuaki; Kashima, Hideo; Sugaya, Masakazu; Terada, Koichi; Sakairi, Minoru

2014-06-30

There is a need for more rapid methods for the detection of explosive particles. We have developed a novel real-time analysis technique for explosive particles that uses a cyclone particle concentrator. This technique can analyze sample surfaces for the presence of particles from explosives such as TNT and RDX within 3 s, which is much faster than is possible by conventional methods. Particles are detached from the sample surface with air jet pulses, and then introduced into a cyclone particle concentrator with a high pumping speed of about 80 L/min. A vaporizer placed at the bottom of the cyclone particle concentrator immediately converts the particles into a vapor. The vapor is then ionized in the atmospheric pressure chemical ionization (APCI) source of a linear ion trap mass spectrometer. An online connection between the vaporizer and a mass spectrometer enables high-speed detection within a few seconds, compared with the conventional off-line heating method that takes more than 10 s to raise the temperature of a sample filter unit. Since the configuration enriched the number density of explosive particles by about 80 times compared with that without the concentrator, a sub-ng amount of TNT particles on a surface was detectable. The detection limit of our technique is comparable with that of an explosives trace detector using ion mobility spectrometry. The technique will be beneficial for trace detection in security applications, because it detects explosive particles on the surface more speedily than conventional methods. Copyright © 2014 John Wiley & Sons, Ltd.

Thermodynamics of phase-separating nanoalloys: Single particles and particle assemblies

NASA Astrophysics Data System (ADS)

Fèvre, Mathieu; Le Bouar, Yann; Finel, Alphonse

2018-05-01

The aim of this paper is to investigate the consequences of finite-size effects on the thermodynamics of nanoparticle assemblies and isolated particles. We consider a binary phase-separating alloy with a negligible atomic size mismatch, and equilibrium states are computed using off-lattice Monte Carlo simulations in several thermodynamic ensembles. First, a semi-grand-canonical ensemble is used to describe infinite assemblies of particles with the same size. When decreasing the particle size, we obtain a significant decrease of the solid/liquid transition temperatures as well as a growing asymmetry of the solid-state miscibility gap related to surface segregation effects. Second, a canonical ensemble is used to analyze the thermodynamic equilibrium of finite monodisperse particle assemblies. Using a general thermodynamic formulation, we show that a particle assembly may split into two subassemblies of identical particles. Moreover, if the overall average canonical concentration belongs to a discrete spectrum, the subassembly concentrations are equal to the semi-grand-canonical equilibrium ones. We also show that the equilibrium of a particle assembly with a prescribed size distribution combines a size effect and the fact that a given particle size assembly can adopt two configurations. Finally, we have considered the thermodynamics of an isolated particle to analyze whether a phase separation can be defined within a particle. When studying rather large nanoparticles, we found that the region in which a two-phase domain can be identified inside a particle is well below the bulk phase diagram, but the concentration of the homogeneous core remains very close to the bulk solubility limit.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blümel, C., E-mail: karl-ernst.wirth@fau.de; Schmidt, J., E-mail: karl-ernst.wirth@fau.de; Dielesen, A., E-mail: karl-ernst.wirth@fau.de

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 ratiomore » 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.« less

Magnetic particle tracking for nonspherical particles in a cylindrical fluidized bed.

PubMed

Buist, Kay A; Jayaprakash, Pavithra; Kuipers, J A M; Deen, Niels G; Padding, Johan T

2017-12-01

In granular flow operations, often particles are nonspherical. This has inspired a vast amount of research in understanding the behavior of these particles. Various models are being developed to study the hydrodynamics involving nonspherical particles. Experiments however are often limited to obtain data on the translational motion only. This paper focusses on the unique capability of Magnetic Particle Tracking to track the orientation of a marker in a full 3-D cylindrical fluidized bed. Stainless steel particles with the same volume and different aspect ratios are fluidized at a range of superficial gas velocities. Spherical and rod-like particles show distinctly different fluidization behavior. Also, the distribution of angles for rod-like particles changes with position in the fluidized bed as well as with the superficial velocity. Magnetic Particle Tracking shows its unique capability to study both spatial distribution and orientation of the particles allowing more in-depth validation of Discrete Particle Models. © 2017 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers , 63: 5335-5342, 2017.

Parameters influencing the course of passive drug loading into lipid nanoemulsions.

PubMed

Göke, Katrin; Bunjes, Heike

2018-05-01

Passive drug loading can be used to effectively identify suitable colloidal lipid carrier systems for poorly water-soluble drugs. This method comprises incubation of preformed carrier systems with drug powder and subsequent determination of the resulting drug load of the carrier particles. Until now, the passive loading mechanism is unknown, which complicates reliable routine use. In this work, the influence of drug characteristics on the course of passive loading was investigated systematically varying drug surface area and drug solubility. Fenofibrate and flufenamic acid were used as model drugs; the carrier system was a trimyristin nanodispersion. Loading progress was analyzed by UV spectroscopy or by a novel method based on differential scanning calorimetry. While increasing drug solubility by micelle incorporation did not speed up passive loading, a large drug surface area and high water solubility were key parameters for fast loading. Since both factors are crucial in drug dissolution as described by the Noyes-Whitney equation, these findings point to a dissolution-diffusion-based passive loading mechanism. Accordingly, passive loading also occurred when drug and carrier particles were separated by a dialysis membrane. Knowledge of the loading mechanism allows optimizing the conditions for future passive loading studies and assessing the limitations of the method. Copyright © 2017 Elsevier B.V. All rights reserved.

Mechanical properties of Mo-Si-B alloys fabricated by using core-shell powder with dispersion of yttria nanoparticles

NASA Astrophysics Data System (ADS)

Byun, Jong Min; Bang, Su-Ryong; Choi, Won June; Kim, Min Sang; Noh, Goo Won; Kim, Young Do

2017-01-01

In recent years, refractory materials with excellent high-temperature properties have been in the spotlight as a next generation's high-temperature materials. Among these, Mo-Si-B alloys composed of two intermetallic compound phases (Mo5SiB2 and Mo3Si) and a ductile α-Mo phase have shown an outstanding thermal properties. However, due to the brittleness of the intermetallic compound phases, Mo-Si-B alloys were restricted to apply for the structural materials. So, to enhance the mechanical properties of Mo-Si-B alloys, many efforts to add rare-earth oxide particles in the Mo-Si-B alloy were performed to induce the improvement of strength and fracture toughness. In this study, to investigate the effect of adding nano-sized Y2O3 particles in Mo-Si-B alloy, a core-shell powder consisting of intermetallic compound phases as the core and nano-sized α-Mo and Y2O3 particles surrounding the core was fabricated. Then pressureless sintering was carried out at 1400 °C for 3 h, and the mechanical properties of sintered bodies with different amounts of Y2O3 particles were evaluated by Vickers hardness and 3-point bending test. Vickers hardness was improved by dispersed Y2O3 particles in the Mo-Si-B alloy. Especially, Mo-3Si-1B-1.5Y2O3 alloy had the highest value, 589 Hv. The fracture toughness was measured using Mo-3Si-1B-1.5Y2O3 alloy and the value indicated as 13.5 MPa·√m.

Nanocapsular Dispersion of Thymol for Enhanced Dispersibility and Increased Antimicrobial Effectiveness against Escherichia coli O157:H7 and Listeria monocytogenes in Model Food Systems

PubMed Central

Shah, Bhavini; Davidson, P. Michael

2012-01-01

Essential oils are marginally soluble in water, making it challenging to evenly disperse them in foods and resulting in an increased tendency to bind with food lipids and proteins, resulting in lowered antimicrobial efficacy. In the current study, free and nano-dispersed (ND) thymol were compared in terms of their antimicrobial efficacies against Escherichia coli O157:H7 ATCC 43889 and 43894 and Listeria monocytogenes strains Scott A and 101 in apple cider and 2% reduced-fat milk. Apple cider was adjusted to pHs 5.5 and 3.5, and antimicrobial tests were performed at 0.3-, 0.5-, 0.75-, and 1.0-g/liter thymol concentrations at 35, 32, 25, and 4°C. Overall, 0.5 and 1.0 g/liter thymol in nano-dispersion and along with free thymol were inhibitory and bactericidal, respectively, against bacterial strains under all treatment conditions. At pH 5.5, 0.5 g/liter ND thymol was bacteriostatic against L. monocytogenes and E. coli for up to 48 h. At pH 3.5, L. monocytogenes controls did not survive beyond 12 h but E. coli survived and was inhibited by 0.5 g/liter ND thymol after 12 and 48 h in apple cider. E. coli strains were significantly sensitive to 4°C and pH 3.5 (P < 0.05). When bacteria were tested in 2% reduced-fat milk at 35 or 32°C, ND and free thymol demonstrated inhibition at 4.5 g/liter. Thus, the current technology seems to be promising and novel, enabling thymol-containing nano-dispersions that are not only transparent but also effective against pathogens in food applications, especially in clear beverages. PMID:23023745

Online single particle analysis of ice particle residuals from mountain-top mixed-phase clouds using laboratory derived particle type assignment

NASA Astrophysics Data System (ADS)

Schmidt, Susan; Schneider, Johannes; Klimach, Thomas; Mertes, Stephan; Schenk, Ludwig Paul; Kupiszewski, Piotr; Curtius, Joachim; Borrmann, Stephan

2017-01-01

In situ single particle analysis of ice particle residuals (IPRs) and out-of-cloud aerosol particles was conducted by means of laser ablation mass spectrometry during the intensive INUIT-JFJ/CLACE campaign at the high alpine research station Jungfraujoch (3580 m a.s.l.) in January-February 2013. During the 4-week campaign more than 70 000 out-of-cloud aerosol particles and 595 IPRs were analyzed covering a particle size diameter range from 100 nm to 3 µm. The IPRs were sampled during 273 h while the station was covered by mixed-phase clouds at ambient temperatures between -27 and -6 °C. The identification of particle types is based on laboratory studies of different types of biological, mineral and anthropogenic aerosol particles. The outcome of these laboratory studies was characteristic marker peaks for each investigated particle type. These marker peaks were applied to the field data. In the sampled IPRs we identified a larger number fraction of primary aerosol particles, like soil dust (13 ± 5 %) and minerals (11 ± 5 %), in comparison to out-of-cloud aerosol particles (2.4 ± 0.4 and 0.4 ± 0.1 %, respectively). Additionally, anthropogenic aerosol particles, such as particles from industrial emissions and lead-containing particles, were found to be more abundant in the IPRs than in the out-of-cloud aerosol. In the out-of-cloud aerosol we identified a large fraction of aged particles (31 ± 5 %), including organic material and secondary inorganics, whereas this particle type was much less abundant (2.7 ± 1.3 %) in the IPRs. In a selected subset of the data where a direct comparison between out-of-cloud aerosol particles and IPRs in air masses with similar origin was possible, a pronounced enhancement of biological particles was found in the IPRs.

The Effect of Sulphate Anions on the Ultrafine Titania Nucleation

NASA Astrophysics Data System (ADS)

Kotsyubynsky, Volodymyr O.; Myronyuk, Ivan F.; Chelyadyn, Volodymyr L.; Hrubiak, Andriy B.; Moklyak, Volodymyr V.; Fedorchenko, Sofia V.

2017-05-01

The phenomenological model of sulphate anions effect on the nanodispersed titania synthesis during hydrolysis of titanium tetrachloride was studied. It was proposed that both chelating and bridging bidentate complexes formation between sulphate anions and octahedrally coordinated [Ti(OH)h(OH2)6-h](4-h)+ mononers is the determinative factor for anatase phase nucleation.

Magnetic particles

NASA Technical Reports Server (NTRS)

Chang, Manchium (Inventor); Colvin, Michael S. (Inventor)

1989-01-01

Magnetic polymer particles are formed by swelling porous, polymer particles and impregnating the particles with an aqueous solution of precursor magnetic metal salt such as an equimolar mixture of ferrous chloride and ferric chloride. On addition of a basic reagent such as dilute sodium hydroxide, the metal salts are converted to crystals of magnetite which are uniformly contained througout the pores of the polymer particle. The magnetite content can be increased and neutral buoyancy achieved by repetition of the impregnaton and neutralization steps to adjust the magnetite content to a desired level.

Acoustic particle separation

NASA Technical Reports Server (NTRS)

Barmatz, M. B.; Stoneburner, J. D.; Jacobi, N.; Wang, T. (Inventor)

1985-01-01

A method is described which uses acoustic energy to separate particles of different sizes, densities, or the like. The method includes applying acoustic energy resonant to a chamber containing a liquid of gaseous medium to set up a standing wave pattern that includes a force potential well wherein particles within the well are urged towards the center, or position of minimum force potential. A group of particles to be separated is placed in the chamber, while a non-acoustic force such as gravity is applied, so that the particles separate with the larger or denser particles moving away from the center of the well to a position near its edge and progressively smaller lighter particles moving progressively closer to the center of the well. Particles are removed from different positions within the well, so that particles are separated according to the positions they occupy in the well.

Adhesive particle shielding

DOEpatents

Klebanoff, Leonard Elliott [Dublin, CA; Rader, Daniel John [Albuquerque, NM; Walton, Christopher [Berkeley, CA; Folta, James [Livermore, CA

2009-01-06

An efficient device for capturing fast moving particles has an adhesive particle shield that includes (i) a mounting panel and (ii) a film that is attached to the mounting panel wherein the outer surface of the film has an adhesive coating disposed thereon to capture particles contacting the outer surface. The shield can be employed to maintain a substantially particle free environment such as in photolithographic systems having critical surfaces, such as wafers, masks, and optics and in the tools used to make these components, that are sensitive to particle contamination. The shield can be portable to be positioned in hard-to-reach areas of a photolithography machine. The adhesive particle shield can incorporate cooling means to attract particles via the thermophoresis effect.

Particle astronomy and particle physics from the moon - The particle observatory

NASA Technical Reports Server (NTRS)

Wilson, Thomas L.

1990-01-01

Promising experiments from the moon using particle detectors are discussed, noting the advantage of the large flux collecting power Pc offered by the remote, stable environment of a lunar base. An observatory class of particle experiments is presented, based upon proposals at NASA's recent Stanford workshop. They vary from neutrino astronomy, particle astrophysics, and cosmic ray experiments to space physics and fundamental physics experiments such as proton decay and 'table-top' arrays. This research is background-limited on earth, and it is awkward and unrealistic in earth orbit, but is particularly suited for the moon where Pc can be quite large and the instrumentation is not subject to atmospheric erosion as it is (for large t) in low earth orbit.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stengl, Vaclav, E-mail: stengl@iic.cas.cz; Bludska, Jana; Oplustil, Frantisek

Highlights: {yields} New nano-dispersive materials for warfare agents decontamination. {yields} 95% decontamination activities for sulphur mustard. {yields} New materials base on titanium and manganese oxides. -- Abstract: Titanium(IV)-manganese(IV) nano-dispersed oxides were prepared by a homogeneous hydrolysis of potassium permanganate and titanium(IV) oxo-sulphate with 2-chloroacetamide. Synthesised samples were characterised using Brunauer-Emmett-Teller (BET) surface area and Barrett-Joiner-Halenda porosity (BJH), X-ray diffraction (XRD), infrared spectroscopy (IR), and scanning electron microscopy (SEM). These oxides were taken for an experimental evaluation of their reactivity with sulphur mustard (HD or bis(2-chloroethyl)sulphide) and soman (GD or (3,3'-dimethylbutan-2-yl)-methylphosphonofluoridate). Mn{sup 4+} content affects the decontamination activity; with increasing Mn{supmore » 4+} content the activity increases for sulphur mustard and decreases for soman. The best decontamination activities for sulphur mustard and soman were observed for samples TiMn{sub 3}7 with 18.6 wt.% Mn and TiMn{sub 5} with 2.1 wt.% Mn, respectively.« less

Ultrafine particle concentration and new particle formation in a coastal arid environment

NASA Astrophysics Data System (ADS)

Alfoldy, Balint; Kotob, Mohamed; Obbard, Jeffrey P.

2017-04-01

Arid environments can be generally characterised by high coarse aerosol load due to the wind-driven erosion of the upper earth crust (i.e. Aeolian dust). On the other hand, anthropogenic activities and/or natural processes also generate significant numbers of particles in the ultrafine size range. Ultrafine particles (also referred as nano-particles) is considered as aerosol particles with the diameter less than 100 nm irrespectively their chemical composition. Due to their small size, these particles represent negligible mass portion in the total atmospheric particulate mass budget. On the other hand, these particles represent the majority of the total particle number budget and have the major contribution in the total aerosol surface distribution. Ultrafine particles are characterised by high mobility (diffusion) and low gravitational settling velocity. Consequently, these particles can be transported long distances and their atmospheric lifetime is relatively high (i.e. in the Accumulation Mode). Ultrafine particles play important role in the atmosphere as they take part in the atmospheric chemistry (high surface), impact the climate (sulphate vs. black carbon), and implies significant health effects due to their deep lung penetration and high mobility in the body. The Atmospheric Laboratory of Qatar University is conducting real-time monitoring of ultrafine particles and regularly taking aerosol samples for chemical analysis at the university campus. In this paper, recent results are presented regarding the size distribution and chemical composition of the ultrafine aerosol particles. Based on the concentration variation in time, sources of ultrafine particles can be clearly separated from the sources of fine or coarse particles. Several cases of new particle formation events have been observed and demonstrated in the paper, however, the precursors of the secondary aerosol particles are still unknown. Literature references suggest that among the sulphuric acid

Particle generator

DOEpatents

Hess, Wayne P.; Joly, Alan G.; Gerrity, Daniel P.; Beck, Kenneth M.; Sushko, Peter V.; Shlyuger, Alexander L.

2005-06-28

Energy tunable solid state sources of neutral particles are described. In a disclosed embodiment, a halogen particle source includes a solid halide sample, a photon source positioned to deliver photons to a surface of the halide, and a collimating means positioned to accept a spatially defined plume of hyperthermal halogen particles emitted from the sample surface.

Impact of yttria stabilized zirconia nanoinclusions on the thermal conductivity of n-type Si80Ge20 alloys prepared by spark plasma sintering

NASA Astrophysics Data System (ADS)

Lahwal, Ali; Bhattacharya, S.; He, Jian; Wu, Di; Peterson, A.; Poon, S. J.; Williams, L.; Dehkordi, A. Mehdizadeh; Tritt, T. M.

2015-04-01

Nanocomposites have become a new paradigm for thermoelectric research in recent years and have resulted in the reduction of thermal conductivity via the nano-inclusion and grain boundary scattering. In this work, we report the preparation and thermoelectric study of SiGe-yttria stabilized zirconia (YSZ) nanocomposites prepared by Spark Plasma Sintering (SPS). We experimentally investigated the reduction of lattice thermal conductivity (κL) in the temperature range (30-800 K) of n-type Si80Ge20P2 alloys with the incorporation of YSZ nanoparticles (20-40 nm diameter) into the Si-Ge matrix. These samples synthesized by using the SPS technique were found to have densities > 95% of the theoretical density. The thermal conductivity, at both low and high temperatures, was measured by steady state and laser flash techniques, respectively. At room temperature, we observed approximately a 50% reduction in the lattice thermal conductivity as result of adding 10% YSZ by volume to the Si80Ge20P2 host matrix. A phenomenological model developed by Callaway was used to corroborate both the temperature dependence and reduction of κ L over the measured temperature range (30-800 K) of both Si80Ge20P2 and Si80Ge20P2 + YSZ samples. The observed κL is discussed and interpreted in terms of various phonon scattering mechanisms such as alloy disorder, the Umklapp phonon scattering, and boundary scattering. In addition, a contribution from the phonon scattering by YSZ nanoparticles was further included to account for the κL of Si80Ge20P2 + YSZ sample. The theoretical calculations are in reasonably good agreement with the experimental results for both the Si80Ge20P2 and Si80Ge20P2 + YSZ alloys.

Colloids exposed to random potential energy landscapes: From particle number density to particle-potential and particle-particle interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bewerunge, Jörg; Capellmann, Ronja F.; Platten, Florian

2016-07-28

Colloidal particles were exposed to a random potential energy landscape that has been created optically via a speckle pattern. The mean particle density as well as the potential roughness, i.e., the disorder strength, were varied. The local probability density of the particles as well as its main characteristics were determined. For the first time, the disorder-averaged pair density correlation function g{sup (1)}(r) and an analogue of the Edwards-Anderson order parameter g{sup (2)}(r), which quantifies the correlation of the mean local density among disorder realisations, were measured experimentally and shown to be consistent with replica liquid state theory results.

Effects of Initial Particle Distribution on an Energetic Dispersal of Particles

NASA Astrophysics Data System (ADS)

Rollin, Bertrand; Ouellet, Frederick; Koneru, Rahul; Garno, Joshua; Durant, Bradford

2017-11-01

Accurate predictions of the late time solid particle cloud distribution ensuing an explosive dispersal of particles is an extremely challenging problem for compressible multiphase flow simulations. The source of this difficulty is twofold: (i) The complex sequence of events taking place. Indeed, as the blast wave crosses the surrounding layer of particles, compaction occurs shortly before particles disperse radially at high speed. Then, during the dispersion phase, complex multiphase interactions occurs between particles and detonation products. (ii) Precise characterization of the explosive and particle distribution is virtually impossible. In this numerical experiment, we focus on the sensitivity of late time particle cloud distributions relative to carefully designed initial distributions, assuming the explosive is well described. Using point particle simulations, we study the case of a bed of glass particles surrounding an explosive. Constraining our simulations to relatively low initial volume fractions to prevent reaching of the close packing limit, we seek to describe qualitatively and quantitatively the late time dependency of a solid particle cloud on its distribution before the energy release of an explosive. This work was supported by the U.S. DoE, NNSA, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

Particle-Surface Interaction Model and Method of Determining Particle-Surface Interactions

NASA Technical Reports Server (NTRS)

Hughes, David W. (Inventor)

2012-01-01

A method and model of predicting particle-surface interactions with a surface, such as the surface of a spacecraft. The method includes the steps of: determining a trajectory path of a plurality of moving particles; predicting whether any of the moving particles will intersect a surface; predicting whether any of the particles will be captured by the surface and/or; predicting a reflected trajectory and velocity of particles reflected from the surface.

Effect of particle hardness on the penetration behavior of fabrics intercalated with dry particles and concentrated particle-fluid suspensions.

PubMed

Kalman, Dennis P; Merrill, Richard L; Wagner, Norman J; Wetzel, Eric D

2009-11-01

The penetration behavior of Kevlar fabric intercalated with dry particles and shear thickening fluids (STF), highly concentrated fluid-particle suspensions, is presented. In particular, the role of particle hardness is explored by comparing fabric treatments containing SiO(2) particles, which are significantly harder than Kevlar, to treatments containing softer poly(methyl methacrylate) (PMMA) particles. The fabric testing includes yarn pull-out, quasi-static spike puncture, and ballistic penetration resistance, performed on single fabric layers. It was found that both dry particle and STF treatments resulted in improvements in fabric properties relative to neat or poly(ethylene glycol) (PEG) treated fabrics. On comparison of treatments with different particle hardness, the SiO(2) materials performed better in all tests than comparable PMMA materials, although the SiO(2) treatments caused yarn failure in pull-out testing, reducing the total pull-out energy. In addition, resistance to yarn pull-out was found to be substantially higher for STF-treated fabrics than for dry particle treated fabrics. However, both dry particle addition and STF treatments exhibited comparable enhancements in puncture and ballistic resistance. These observations suggest that viscous stress transfer, friction, and physical entrainment of hard particles into filaments contribute to the demonstrated improvements in the properties of protective fabrics treated with shear thickening fluids.

Development of Oxide Dispersion Strengthened (ODS) Ferritic Steel Through Powder Forging

NASA Astrophysics Data System (ADS)

Kumar, Deepak; Prakash, Ujjwal; Dabhade, Vikram V.; Laha, K.; Sakthivel, T.

2017-04-01

Oxide dispersion strengthened (ODS) ferritic steels are candidates for cladding tubes in fast breeder nuclear reactors. In this study, an 18%Cr ODS ferritic steel was prepared through powder forging route. Elemental powders with a nominal composition of Fe-18Cr-2 W-0.2Ti (composition in wt.%) with 0 and 0.35% yttria were prepared by mechanical alloying in a Simoloyer attritor under argon atmosphere. The alloyed powders were heated in a mild steel can to 1473 K under flowing hydrogen atmosphere. The can was then hot forged. Steps of sealing, degassing and evacuation are eliminated by using powder forging. Heating ODS powder in hydrogen atmosphere ensures good bonding between alloy powders. A dense ODS alloy with an attractive combination of strength and ductility was obtained after re-forging. On testing at 973 K, a loss in ductility was observed in yttria-containing alloy. The strength and ductility increased with increase in strain rate at 973 K. Reasons for this are discussed. The ODS alloy exhibited a recrystallized microstructure which is difficult to achieve by extrusion. No prior particle boundaries were observed after forging. The forged compacts exhibited isotropic mechanical properties. It is suggested that powder forging may offer several advantages over the traditional extrusion/HIP routes for fabrication of ODS alloys.

Glass/Ceramic Composites for Sealing Solid Oxide Fuel Cells

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Choi, Sung R.

2007-01-01

A family of glass/ceramic composite materials has been investigated for use as sealants in planar solid oxide fuel cells. These materials are modified versions of a barium calcium aluminosilicate glass developed previously for the same purpose. The composition of the glass in mole percentages is 35BaO + 15CaO + 5Al2O3 + 10B2O3 + 35SiO2. The glass seal was found to be susceptible to cracking during thermal cycling of the fuel cells. The goal in formulating the glass/ ceramic composite materials was to (1) retain the physical and chemical advantages that led to the prior selection of the barium calcium aluminosilicate glass as the sealant while (2) increasing strength and fracture toughness so as to reduce the tendency toward cracking. Each of the composite formulations consists of the glass plus either of two ceramic reinforcements in a proportion between 0 and 30 mole percent. One of the ceramic reinforcements consists of alumina platelets; the other one consists of particles of yttria-stabilized zirconia wherein the yttria content is 3 mole percent (3YSZ). In preparation for experiments, panels of the glass/ceramic composites were hot-pressed and machined into test bars.

Magnetic particles

NASA Technical Reports Server (NTRS)

Chang, Manchium (Inventor); Colvin, Michael S. (Inventor); Rembaum, Alan (Inventor); Richards, Gil F. (Inventor)

1987-01-01

Metal oxide containing polymers and particularly styrene, acrylic or protein polymers containing fine, magnetic iron oxide particles are formed by combining a NO.sub.2 -substituted polymer with an acid such as hydrochloric acid in the presence of metal, particularly iron particles. The iron is oxidized to fine, black Fe.sub.3 O.sub.4 particles which deposit selectively on the polymer particles. Nitrated polymers are formed by reacting functionally substituted, nitrated organic compounds such as trinitrobenzene sulfonate or dinitrofluoro benzene with a functionally coreactive polymer such as an amine modified acrylic polymer or a protein. Other transition metals such as cobalt can also be incorporated into polymers using this method.

Study of Nanodispersed Iron Oxides Produced in Steel Drilling by Contracted Electric-Arc Air Plasma Torch

NASA Astrophysics Data System (ADS)

Stefanov, P.; Galanov, D.; Vissokov, G.; Paneva, D.; Kunev, B.; Mitov, I.

2008-06-01

The optimal conditions on the plasma-forming gas flowrate, discharge current and voltage, distance between the plasma-torch nozzle and the metal plate surface for the process of penetration in and vaporization of steel plates by the contracted electric-arc air plasma torch accompanied by water quenching, were determined. The X-ray structural and phase studies as well as Mössbauer and electron microscope studies on the samples treated were performed. It was demonstrated that the vaporized elemental iron was oxidized by the oxygen present in the air plasma jet to form iron oxides (wüstite, magnetite, hematite), which, depending on their mass ratios, determined the color of the iron oxide pigments, namely, beginning from light yellow, through deep yellow, light brown, deep brown, violet, red-violet, to black. A high degree of dispersity of the iron oxides is thus produced, with an averaged diameter of the particles below 500 nm, and their defective crystal structure form the basis of their potential application as components of iron-containing catalysts and pigments.

Ice particle collisions

NASA Astrophysics Data System (ADS)

Sampara, Naresh; Turnbull, Barbara; Hill, Richard; Swift, Michael

2017-04-01

Granular interactions of ice occur in a range of geophysical, astrophysical and industrial applications. For example, Saturn's Rings are composed of icy particles from micrometers to kilometres in size - inertial and yet too small to interact gravitationally. In clouds, ice crystals are smashed to pieces before they re-aggregate to for snow floccules in a process that is very much open to interpretation. In a granular flow of ice particles, the energy spent in collisions can lead to localized surface changes and wetting, which in turn can promote aggregation. To understand the induced wetting and its effects, we present two novel experimental methods which provide snippets of insight into the collisional behaviour of macroscopic ice particles. Experiment 1: Microgravity experiments provide minute details of the contact between the ice particles during the collision. A diamagnetic levitation technique, as alternative to the parabolic flight or falling tower experiments, was used to understand the collisional behaviour of individual macroscopic icy bodies. A refrigerated cylinder, that can control ambient conditions, was inserted into the bore of an 18 Tesla superconducting magnet and cooled to -10°C. Initial binary collisions were created, where one 4 mm ice particle was levitated in the magnet bore whilst another particle was dropped vertically from the top of the bore. The trajectories of both particles were captured by high speed video to provide the three-dimensional particle velocities and track the collision outcome. Introducing complexity, multiple particles were levitated in the bore and an azimuthal turbulent air flow introduced, allowing the particles to collide with other particles within a coherent fluid structure (mimicking Saturn's rings, or an eddy in a cloud). In these experiments, a sequence of collisions occur, each one different to the previous one due to the changes in surface characteristics created by the collisions themselves. Aggregation

Microfabricated particle focusing device

DOEpatents

Ravula, Surendra K.; Arrington, Christian L.; Sigman, Jennifer K.; Branch, Darren W.; Brener, Igal; Clem, Paul G.; James, Conrad D.; Hill, Martyn; Boltryk, Rosemary June

2013-04-23

A microfabricated particle focusing device comprises an acoustic portion to preconcentrate particles over large spatial dimensions into particle streams and a dielectrophoretic portion for finer particle focusing into single-file columns. The device can be used for high throughput assays for which it is necessary to isolate and investigate small bundles of particles and single particles.

Effect of particle size distribution on 3D packings of spherical particles

NASA Astrophysics Data System (ADS)

Taiebat, Mahdi; Mutabaruka, Patrick; Pellenq, Roland; Radjai, Farhang

2017-06-01

We use molecular dynamics simulations of frictionless spherical particles to investigate a class of polydisperse granular materials in which the particle size distribution is uniform in particle volumes. The particles are assembled in a box by uniaxial compaction under the action of a constant stress. Due to the absence of friction and the nature of size distribution, the generated packings have the highest packing fraction at a given size span, defined as the ratio α of the largest size to the smallest size. We find that, up to α = 5, the packing fraction is a nearly linear function of α. While the coordination number is nearly constant due to the isostatic nature of the packings, we show that the connectivity of the particles evolves with α. In particular, the proportion of particles with 4 contacts represents the largest proportion of particles mostly of small size. We argue that this particular class of particles occurs as a result of the high stability of local configurations in which a small particle is stuck by four larger particles.

Coarse-grained discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers [Discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers

DOE PAGES

Verma, Vikrant; Li, Tingwen; De Wilde, Juray

2017-05-26

Vortex chambers allow the generation of rotating fluidized beds, offering high-G intensified gas-solid contact, gas-solids separation and solids-solids segregation. Focusing on binary particle mixtures and fixing the density and diameter of the heavy/large particles, transient batch CFD-coarse-grained DPM simulations were carried out with varying densities or sizes of the light/small particles to evaluate to what extent combining these three functionalities is possible within a vortex chamber of given design. Both the rate and quality of segregation were analyzed. Within a relatively wide density and size range, fast and efficient segregation takes place, with an inner and slower rotating bed ofmore » the lighter/small particles forming within the outer and faster rotating bed of the heavier/large particles. Simulations show that the contamination of the outer bed with lighter particles occurs more easily than contamination of the inner bed with heavier particles and increases with decreasing difference in size or density of the particles. Bubbling in the inner bed is observed with an inner bed of very low density or small particles. Porosity plots show that vortex chambers with a sufficient number of gas inlet slots have to be used to guarantee a uniform gas distribution and particle bed. Lastly, the flexibility of particle segregation in vortex chambers with respect to the gas flow rate is demonstrated.« less

Coarse-grained discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers [Discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verma, Vikrant; Li, Tingwen; De Wilde, Juray

Vortex chambers allow the generation of rotating fluidized beds, offering high-G intensified gas-solid contact, gas-solids separation and solids-solids segregation. Focusing on binary particle mixtures and fixing the density and diameter of the heavy/large particles, transient batch CFD-coarse-grained DPM simulations were carried out with varying densities or sizes of the light/small particles to evaluate to what extent combining these three functionalities is possible within a vortex chamber of given design. Both the rate and quality of segregation were analyzed. Within a relatively wide density and size range, fast and efficient segregation takes place, with an inner and slower rotating bed ofmore » the lighter/small particles forming within the outer and faster rotating bed of the heavier/large particles. Simulations show that the contamination of the outer bed with lighter particles occurs more easily than contamination of the inner bed with heavier particles and increases with decreasing difference in size or density of the particles. Bubbling in the inner bed is observed with an inner bed of very low density or small particles. Porosity plots show that vortex chambers with a sufficient number of gas inlet slots have to be used to guarantee a uniform gas distribution and particle bed. Lastly, the flexibility of particle segregation in vortex chambers with respect to the gas flow rate is demonstrated.« less

Numerical investigation of compaction of deformable particles with bonded-particle model

NASA Astrophysics Data System (ADS)

Dosta, Maksym; Costa, Clara; Al-Qureshi, Hazim

2017-06-01

In this contribution, a novel approach developed for the microscale modelling of particles which undergo large deformations is presented. The proposed method is based on the bonded-particle model (BPM) and multi-stage strategy to adjust material and model parameters. By the BPM, modelled objects are represented as agglomerates which consist of smaller ideally spherical particles and are connected with cylindrical solid bonds. Each bond is considered as a separate object and in each time step the forces and moments acting in them are calculated. The developed approach has been applied to simulate the compaction of elastomeric rubber particles as single particles or in a random packing. To describe the complex mechanical behaviour of the particles, the solid bonds were modelled as ideally elastic beams. The functional parameters of solid bonds as well as material parameters of bonds and primary particles were estimated based on the experimental data for rubber spheres. Obtained results for acting force and for particle deformations during uniaxial compression are in good agreement with experimental data at higher strains.

Effect of particle-particle shearing on the bioleaching of sulfide minerals.

PubMed

Chong, N; Karamanev, D G; Margaritis, A

2002-11-05

The biological leaching of sulfide minerals, used for the production of gold, copper, zinc, cobalt, and other metals, is very often carried out in slurry bioreactors, where the shearing between sulfide particles is intensive. In order to be able to improve the efficiency of the bioleaching, it is of significant importance to know the effect of particle shearing on the rate of leaching. The recently proposed concept of ore immobilization allowed us to study the effect of particle shearing on the rate of sulfide (pyrite) leaching by Thiobacillus ferrooxidans. Using this concept, we designed two very similar bioreactors, the main difference between which was the presence and absence of particle-particle shearing. It was shown that when the oxygen mass transfer was not the rate-limiting step, the rate of bioleaching in the frictionless bioreactor was 2.5 times higher than that in a bioreactor with particle friction (shearing). The concentration of free suspended cells in the frictionless bioreactor was by orders of magnitude lower than that in the frictional bioreactor, which showed that particle friction strongly reduces the microbial attachment to sulfide surface, which, in turn, reduces the rate of bioleaching. Surprisingly, it was found that formation of a layer of insoluble iron salts on the surface of sulfide particles is much slower under shearless conditions than in the presence of particle-particle shearing. This was explained by the effect of particle friction on liquid-solid mass transfer rate. The results of this study show that reduction of the particle friction during bioleaching of sulfide minerals can bring important advantages not only by increasing significantly the bioleaching rate, but also by increasing the rate of gas-liquid oxygen mass transfer, reducing the formation of iron precipitates and reducing the energy consumption. One of the efficient methods for reduction of particle friction is ore immobilization in a porous matrix. Copyright 2002

Metal release from stainless steel particles in vitro-influence of particle size.

PubMed

Midander, K; Pan, J; Wallinder, I Odnevall; Leygraf, C

2007-01-01

Human inhalation of airborne metallic particles is important for health risk assessment. To study interactions between metallic particles and the human body, metal release measurements of stainless steel powder particles were performed in two synthetic biological media simulating lung-like environments. Particle size and media strongly influence the metal release process. The release rate of Fe is enhanced compared with Cr and Ni. In artificial lysosomal fluid (ALF, pH 4.5), the accumulated amounts of released metal per particle loading increase drastically with decreasing particle size. The release rate of Fe per unit surface area increases with decreasing particle size. Compared with massive sheet metal, fine powder particles (<4 microm) show similar release rates of Cr and Ni, but a higher release rate of Fe. Release rates in Gamble's solution (pH 7.4), for all powders investigated, are significantly lower compared to ALF. No clear trend is seen related to particle size in Gamble's solution.

Particles Growing in Solutions: Depletion Forces and Instability of Homogeneous Particle Distribution

NASA Technical Reports Server (NTRS)

Chernov, A. A.

2004-01-01

Crystallites, droplets and amorphous precipitates growing from supersaturated solution are surrounded by zones, which are depleted with respect to the molecules they are built of. If two such particles of colloidal size are separated by a distance comparable to their diameters, then the depletion within the gap between particles is deeper than that at the outer portion of the particles. This will cause depletion attraction between the particles should appear. It may cause particle coagulation and decay of the originally homogeneous particle distribution into a system of clouds within which the particle number density is higher, separated by the region of the lower number density. Stability criterion, Q = 4 pi R(exp 3)c/3 >> 1, was analytically found along with typical particle density distribution wavevector q = (Q/I)(exp 1/2)(a/R)(exp 1/4). Here, R and a are the particle and molecular radii, respectively, c is the average molecular number density in solution and I is the squared diffusion length covered by a molecule during a typical time characterizing decay of molecular concentration in solution due to consumption of the molecules by the growing particles.

Development and application of a particle-particle particle-mesh Ewald method for dispersion interactions.

PubMed

Isele-Holder, Rolf E; Mitchell, Wayne; Ismail, Ahmed E

2012-11-07

For inhomogeneous systems with interfaces, the inclusion of long-range dispersion interactions is necessary to achieve consistency between molecular simulation calculations and experimental results. For accurate and efficient incorporation of these contributions, we have implemented a particle-particle particle-mesh Ewald solver for dispersion (r(-6)) interactions into the LAMMPS molecular dynamics package. We demonstrate that the solver's O(N log N) scaling behavior allows its application to large-scale simulations. We carefully determine a set of parameters for the solver that provides accurate results and efficient computation. We perform a series of simulations with Lennard-Jones particles, SPC/E water, and hexane to show that with our choice of parameters the dependence of physical results on the chosen cutoff radius is removed. Physical results and computation time of these simulations are compared to results obtained using either a plain cutoff or a traditional Ewald sum for dispersion.

Role of temperature in the radiation stability of yttria stabilized zirconia under swift heavy ion irradiation: A study from the perspective of nuclear reactor applications

NASA Astrophysics Data System (ADS)

Kalita, Parswajit; Ghosh, Santanu; Sattonnay, Gaël; Singh, Udai B.; Grover, Vinita; Shukla, Rakesh; Amirthapandian, S.; Meena, Ramcharan; Tyagi, A. K.; Avasthi, Devesh K.

2017-07-01

The search for materials that can withstand the harsh radiation environments of the nuclear industry has become an urgent challenge in the face of ever-increasing demands for nuclear energy. To this end, polycrystalline yttria stabilized zirconia (YSZ) pellets were irradiated with 80 MeV Ag6+ ions to investigate their radiation tolerance against fission fragments. To better simulate a nuclear reactor environment, the irradiations were carried out at the typical nuclear reactor temperature (850 °C). For comparison, irradiations were also performed at room temperature. Grazing incidence X-ray diffraction and Raman spectroscopy measurements reveal degradation in crystallinity for the room temperature irradiated samples. No bulk structural amorphization was however observed, whereas defect clusters were formed as indicated by transmission electron microscopy and supported by thermal spike simulation results. A significant reduction of the irradiation induced defects/damage, i.e., improvement in the radiation tolerance, was seen under irradiation at 850 °C. This is attributed to the fact that the rapid thermal quenching of the localized hot molten zones (arising from spike in the lattice temperature upon irradiation) is confined to 850 °C (i.e., attributed to the resistance inflicted on the rapid thermal quenching of the localized hot molten zones by the high temperature of the environment) thereby resulting in the reduction of the defects/damage produced. Our results present strong evidence for the applicability of YSZ as an inert matrix fuel in nuclear reactors, where competitive effects of radiation damage and dynamic thermal healing mechanisms may lead to a strong reduction in the damage production and thus sustain its physical integrity.

Sol-gel dip coating of yttria-stabilized tetragonal zirconia dental ceramic by aluminosilicate nanocomposite as a novel technique to improve the bonding of veneering porcelain.

PubMed

Madani, Azamsadat; Nakhaei, Mohammadreza; Karami, Parisa; Rajabzadeh, Ghadir; Salehi, Sahar; Bagheri, Hossein

2016-01-01

The aim of this in vitro study was to evaluate the effect of silica and aluminosilicate nanocomposite coating of zirconia-based dental ceramic by a sol-gel dip-coating technique on the bond strength of veneering porcelain to the yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in vitro. Thirty Y-TZP blocks (10 mm ×10 mm ×3 mm) were prepared and were assigned to four experimental groups (n=10/group): C, without any further surface treatment as the control group; S, sandblasted using 110 μm alumina powder; Si, silica sol dip coating + calcination; and Si/Al, aluminosilicate sol dip coating + calcination. After preparing Y-TZP samples, a 3 mm thick layer of the recommended porcelain was fired on the coated Y-TZP surface. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis were used to characterize the coating and the nature of the bonding between the coating and zirconia. To examine the zirconia-porcelain bond strength, a microtensile bond strength (μTBS) approach was chosen. FT-IR study showed the formation of silica and aluminosilicate materials. XRD pattern showed the formation of new phases consisting of Si, Al, and Zr in coated samples. SEM showed the formation of a uniform coating on Y-TZP samples. Maximum μTBS values were obtained in aluminosilicate samples, which were significantly increased compared to control and sandblasted groups (P=0.013 and P<0.001, respectively). This study showed that aluminosilicate sol-gel dip coating can be considered as a convenient, less expensive reliable method for improving the bond strength between dental Y-TZP ceramics and veneering porcelain.

On improving the algorithm efficiency in the particle-particle force calculations

NASA Astrophysics Data System (ADS)

Kozynchenko, Alexander I.; Kozynchenko, Sergey A.

2016-09-01

The problem of calculating inter-particle forces in the particle-particle (PP) simulation models takes an important place in scientific computing. Such simulation models are used in diverse scientific applications arising in astrophysics, plasma physics, particle accelerators, etc., where the long-range forces are considered. The inverse-square laws such as Coulomb's law of electrostatic forces and Newton's law of universal gravitation are the examples of laws pertaining to the long-range forces. The standard naïve PP method outlined, for example, by Hockney and Eastwood [1] is straightforward, processing all pairs of particles in a double nested loop. The PP algorithm provides the best accuracy of all possible methods, but its computational complexity is O (Np2), where Np is a total number of particles involved. Too low efficiency of the PP algorithm seems to be the challenging issue in some cases where the high accuracy is required. An example can be taken from the charged particle beam dynamics where, under computing the own space charge of the beam, so-called macro-particles are used (see e.g., Humphries Jr. [2], Kozynchenko and Svistunov [3]).

To Evaluate Effect of Airborne Particle Abrasion using Different Abrasives Particles and Compare Two Commercial Available Zirconia on Flexural Strength on Heat Treatment.

PubMed

Prasad, Hari A; Pasha, Naveed; Hilal, Mohammed; Amarnath, G S; Kundapur, Vinaya; Anand, M; Singh, Sumeet

2017-06-01

The popularity of ceramic restorations can be attributed to its life-like appearance, durability and biocompatibility and therefore ceramic restorations have been widely used for anterior and posterior teeth. Ceramic restorations have esthetic and biocompatible advantages but low fracture resistance. Since it has high flexural strength and fracture resistance, yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) is the dental material most commonly used for the core of ceramic crowns and fixed dental prosthesis. In spite of improved mechanical properties, acceptable marginal adaptation and biocompatibility the whitish opacity of zirconia is an obvious esthetic disadvantage. The zirconia framework is often veneered with conventional feldspathic porcelain to achieve a natural appearance. However it is difficult to achieve sufficient bond strength between zirconia and the veneering material. Achieving sufficient bond strength between the veneering ceramic and the zirconia core is a major challenge in the long term clinical success of veneered zirconia restorations. The main objective of this study is to evaluate the effect of different surface treatments on the fracture strength of the two commercially available Zirconia namely Ceramill and ZR-White (AMANNGIRRBACH and UPCERA) respectively. Two commercially available pre-sinteredyttrium stabilized Zirconia blanks (ZR-White and Ceramill) from AMANNGIRRBACH and UPCERA respectively are used to produce the disc shaped specimens of size (15.2 ± 0.03 mm in diameter and 1.2 ± 0.03 mm thick) from each Zirconia blank. All disc shaped specimens are heated at 1200°C in a furnace for 2 hours to form homogenous tetragonal ZrO 2 . The dimensions of the specimens are measured with a digital caliper (aerospace). The thickness and diameter of each specimen are calculated as the means of 3 measurements made at random sites. 80 discs from each Zirconia blank are divided into ten groups of 8 specimens each. Heat treatment after

To Evaluate Effect of Airborne Particle Abrasion using Different Abrasives Particles and Compare Two Commercial Available Zirconia on Flexural Strength on Heat Treatment

PubMed Central

Prasad, Hari A.; Pasha, Naveed; Hilal, Mohammed; Amarnath, G. S.; Kundapur, Vinaya; Anand, M; Singh, Sumeet

2017-01-01

Background and objective: The popularity of ceramic restorations can be attributed to its life-like appearance, durability and biocompatibility and therefore ceramic restorations have been widely used for anterior and posterior teeth. Ceramic restorations have esthetic and biocompatible advantages but low fracture resistance. Since it has high flexural strength and fracture resistance, yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) is the dental material most commonly used for the core of ceramic crowns and fixed dental prosthesis. In spite of improved mechanical properties, acceptable marginal adaptation and biocompatibility the whitish opacity of zirconia is an obvious esthetic disadvantage. The zirconia framework is often veneered with conventional feldspathic porcelain to achieve a natural appearance. However it is difficult to achieve sufficient bond strength between zirconia and the veneering material. Achieving sufficient bond strength between the veneering ceramic and the zirconia core is a major challenge in the long term clinical success of veneered zirconia restorations. The main objective of this study is to evaluate the effect of different surface treatments on the fracture strength of the two commercially available Zirconia namely Ceramill and ZR-White (AMANNGIRRBACH and UPCERA) respectively. Method: Two commercially available pre-sinteredyttrium stabilized Zirconia blanks (ZR-White and Ceramill) from AMANNGIRRBACH and UPCERA respectively are used to produce the disc shaped specimens of size (15.2 ± 0.03 mm in diameter and 1.2 ± 0.03 mm thick) from each Zirconia blank. All disc shaped specimens are heated at 1200°C in a furnace for 2 hours to form homogenous tetragonal ZrO2. The dimensions of the specimens are measured with a digital caliper (aerospace). The thickness and diameter of each specimen are calculated as the means of 3 measurements made at random sites. 80 discs from each Zirconia blank are divided into ten groups of 8

Dusty-Plasma Particle Accelerator

NASA Technical Reports Server (NTRS)

Foster, John E.

2005-01-01

A dusty-plasma apparatus is being investigated as means of accelerating nanometer- and micrometer-sized particles. Applications for the dusty-plasma particle accelerators fall into two classes: Simulation of a variety of rapidly moving dust particles and micrometeoroids in outer-space environments that include micrometeoroid streams, comet tails, planetary rings, and nebulae and Deposition or implantation of nanoparticles on substrates for diverse industrial purposes that could include hardening, increasing thermal insulation, altering optical properties, and/or increasing permittivities of substrate materials. Relative to prior apparatuses used for similar applications, dusty-plasma particle accelerators offer such potential advantages as smaller size, lower cost, less complexity, and increased particle flux densities. A dusty-plasma particle accelerator exploits the fact that an isolated particle immersed in plasma acquires a net electric charge that depends on the relative mobilities of electrons and ions. Typically, a particle that is immersed in a low-temperature, partially ionized gas, wherein the average kinetic energy of electrons exceeds that of ions, causes the particle to become negatively charged. The particle can then be accelerated by applying an appropriate electric field. A dusty-plasma particle accelerator (see figure) includes a plasma source such as a radio-frequency induction discharge apparatus containing (1) a shallow cup with a biasable electrode to hold the particles to be accelerated and (2) a holder for the substrate on which the particles are to impinge. Depending on the specific design, a pair of electrostatic-acceleration grids between the substrate and discharge plasma can be used to both collimate and further accelerate particles exiting the particle holder. Once exposed to the discharge plasma, the particles in the cup quickly acquire a negative charge. Application of a negative voltage pulse to the biasable electrode results in the

Animating Wall-Bounded Turbulent Smoke via Filament-Mesh Particle-Particle Method.

PubMed

Liao, Xiangyun; Si, Weixin; Yuan, Zhiyong; Sun, Hanqiu; Qin, Jing; Wang, Qiong; Heng, Pheng-Ann; Xiangyun Liao; Weixin Si; Zhiyong Yuan; Hanqiu Sun; Jing Qin; Qiong Wang; Pheng-Ann Heng

2018-03-01

Turbulent vortices in smoke flows are crucial for a visually interesting appearance. Unfortunately, it is challenging to efficiently simulate these appealing effects in the framework of vortex filament methods. The vortex filaments in grids scheme allows to efficiently generate turbulent smoke with macroscopic vortical structures, but suffers from the projection-related dissipation, and thus the small-scale vortical structures under grid resolution are hard to capture. In addition, this scheme cannot be applied in wall-bounded turbulent smoke simulation, which requires efficiently handling smoke-obstacle interaction and creating vorticity at the obstacle boundary. To tackle above issues, we propose an effective filament-mesh particle-particle (FMPP) method for fast wall-bounded turbulent smoke simulation with ample details. The Filament-Mesh component approximates the smooth long-range interactions by splatting vortex filaments on grid, solving the Poisson problem with a fast solver, and then interpolating back to smoke particles. The Particle-Particle component introduces smoothed particle hydrodynamics (SPH) turbulence model for particles in the same grid, where interactions between particles cannot be properly captured under grid resolution. Then, we sample the surface of obstacles with boundary particles, allowing the interaction between smoke and obstacle being treated as pressure forces in SPH. Besides, the vortex formation region is defined at the back of obstacles, providing smoke particles flowing by the separation particles with a vorticity force to simulate the subsequent vortex shedding phenomenon. The proposed approach can synthesize the lost small-scale vortical structures and also achieve the smoke-obstacle interaction with vortex shedding at obstacle boundaries in a lightweight manner. The experimental results demonstrate that our FMPP method can achieve more appealing visual effects than vortex filaments in grids scheme by efficiently simulating

Systems and methods for separating particles utilizing engineered acoustic contrast capture particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaduchak, Gregory; Ward, Michael D.

An apparatus for separating particles from a medium includes a capillary defining a flow path therein that is in fluid communication with a medium source. The medium source includes engineered acoustic contrast capture particle having a predetermined acoustic contrast. The apparatus includes a vibration generator that is operable to produce at least one acoustic field within the flow path. The acoustic field produces a force potential minima for positive acoustic contrast particles and a force potential minima for negative acoustic contrast particles in the flow path and drives the engineered acoustic contrast capture particles to either the force potential minimamore » for positive acoustic contrast particles or the force potential minima for negative acoustic contrast particles.« less

Investigating the settling dynamics of cohesive silt particles with particle-resolving simulations

NASA Astrophysics Data System (ADS)

Sun, Rui; Xiao, Heng; Sun, Honglei

2018-01-01

The settling of cohesive sediment is ubiquitous in aquatic environments, and the study of the settling process is important for both engineering and environmental reasons. In the settling process, the silt particles show behaviors that are different from non-cohesive particles due to the influence of inter-particle cohesive force. For instance, the flocs formed in the settling process of cohesive silt can loosen the packing, and thus the structural densities of cohesive silt beds are much smaller than that of non-cohesive sand beds. While there is a consensus that cohesive behaviors depend on the characteristics of sediment particles (e.g., Bond number, particle size distribution), little is known about the exact influence of these characteristics on the cohesive behaviors. In addition, since the cohesive behaviors of the silt are caused by the inter-particle cohesive forces, the motions of and the contacts among silt particles should be resolved to study these cohesive behaviors in the settling process. However, studies of the cohesive behaviors of silt particles in the settling process based on particle-resolving approach are still lacking. In the present work, three-dimensional settling process is investigated numerically by using CFD-DEM (Computational Fluid Dynamics-Discrete Element Method). The inter-particle collision force, the van der Waals force, and the fluid-particle interaction forces are considered. The numerical model is used to simulate the hindered settling process of silt based on the experimental setup in the literature. The results obtained in the simulations, including the structural densities of the beds, the characteristic lines, and the particle terminal velocity, are in good agreement with the experimental observations in the literature. To the authors' knowledge, this is the first time that the influences of non-dimensional Bond number and particle polydispersity on the structural densities of silt beds have been investigated separately

Pairwise Interaction Extended Point-Particle (PIEP) model for multiphase jets and sedimenting particles

NASA Astrophysics Data System (ADS)

Liu, Kai; Balachandar, S.

2017-11-01

We perform a series of Euler-Lagrange direct numerical simulations (DNS) for multiphase jets and sedimenting particles. The forces the flow exerts on the particles in these two-way coupled simulations are computed using the Basset-Bousinesq-Oseen (BBO) equations. These forces do not explicitly account for particle-particle interactions, even though such pairwise interactions induced by the perturbations from neighboring particles may be important especially when the particle volume fraction is high. Such effects have been largely unaddressed in the literature. Here, we implement the Pairwise Interaction Extended Point-Particle (PIEP) model to simulate the effect of neighboring particle pairs. A simple collision model is also applied to avoid unphysical overlapping of solid spherical particles. The simulation results indicate that the PIEP model provides a more elaborative and complicated movement of the dispersed phase (droplets and particles). Office of Naval Research (ONR) Multidisciplinary University Research Initiative (MURI) project N00014-16-1-2617.

Particle-wall tribology of slippery hydrogel particle suspensions.

PubMed

Shewan, Heather M; Stokes, Jason R; Cloitre, Michel

2017-03-08

Slip is an important phenomenon that occurs during the flow of yield stress fluids like soft materials and pastes. Densely packed suspensions of hydrogel microparticles are used to show that slip is governed by the tribological interactions occurring between the samples and shearing surfaces. Both attractive/repulsive interactions between the dispersed particles and surface, as well as the viscoelasticity of the suspension, are found to play key roles in slip occurring within rheometric flows. We specifically discover that for two completely different sets of microgels, the sliding stress at which slip occurs scales with both the modulus of the particles and the bulk suspension modulus. This suggests that hysteresis losses within the viscoelastic particles contribute to friction forces and thus slip at the particle-surface tribo-contact. It is also found that slip during large amplitude oscillatory shear and steady shear flows share the same generic features.

Analysis of radiation risk from alpha particle component of solar particle events

NASA Technical Reports Server (NTRS)

Cucinotta, F. A.; Townsend, L. W.; Wilson, J. W.; Golightly, M. J.; Weyland, M.

1994-01-01

The solar particle events (SPE) will contain a primary alpha particle component, representing a possible increase in the potential risk to astronauts during an SPE over the often studied proton component. We discuss the physical interactions of alpha particles important in describing the transport of these particles through spacecraft and body shielding. Models of light ion reactions are presented and their effects on energy and linear energy transfer (LET) spectra in shielding discussed. We present predictions of particle spectra, dose, and dose equivalent in organs of interest for SPE spectra typical of those occurring in recent solar cycles. The large events of solar cycle 19 are found to have substantial increase in biological risk from alpha particles, including a large increase in secondary neutron production from alpha particle breakup.

Numerical Study of Particle Damping Mechanism in Piston Vibration System via Particle Dynamics Simulation

NASA Astrophysics Data System (ADS)

Bai, Xian-Ming; Shah, Binoy; Keer, Leon; Wang, Jane; Snurr, Randall

2008-03-01

Mechanical damping systems with granular particles as the damping media have promising applications in extreme temperature conditions. In particle-based damping systems, the mechanical energy is dissipated through the inelastic collision and friction of particles. In the past, many experiments have been performed to investigate the particle damping problems. However, the detailed energy dissipation mechanism is still unclear due to the complex collision and flow behavior of dense particles. In this work, we use 3-D particle dynamics simulation to investigate the damping mechanism of an oscillating cylinder piston immerged in millimeter-size steel particles. The time evolution of the energy dissipation through the friction and inelastic collision is accurately monitored during the damping process. The contribution from the particle-particle interaction and particle-wall interaction is also separated for investigation. The effects of moisture, surface roughness, and density of particles are carefully investigated in the simulation. The comparison between the numerical simulation and experiment is also performed. The simulation results can help us understand the particle damping mechanism and design the new generation of particle damping devices.

Focusing particle concentrator with application to ultrafine particles

DOEpatents

Hering, Susanne; Lewis, Gregory; Spielman, Steven R.

2013-06-11

Technology is presented for the high efficiency concentration of fine and ultrafine airborne particles into a small fraction of the sampled airflow by condensational enlargement, aerodynamic focusing and flow separation. A nozzle concentrator structure including an acceleration nozzle with a flow extraction structure may be coupled to a containment vessel. The containment vessel may include a water condensation growth tube to facilitate the concentration of ultrafine particles. The containment vessel may further include a separate carrier flow introduced at the center of the sampled flow, upstream of the acceleration nozzle of the nozzle concentrator to facilitate the separation of particle and vapor constituents.

Fluidization of spherocylindrical particles

NASA Astrophysics Data System (ADS)

Mahajan, Vinay V.; Nijssen, Tim M. J.; Fitzgerald, Barry W.; Hofman, Jeroen; Kuipers, Hans; Padding, Johan T.

2017-06-01

Multiphase (gas-solid) flows are encountered in numerous industrial applications such as pharmaceutical, food, agricultural processing and energy generation. A coupled computational fluid dynamics (CFD) and discrete element method (DEM) approach is a popular way to study such flows at a particle scale. However, most of these studies deal with spherical particles while in reality, the particles are rarely spherical. The particle shape can have significant effect on hydrodynamics in a fluidized bed. Moreover, most studies in literature use inaccurate drag laws because accurate laws are not readily available. The drag force acting on a non-spherical particle can vary considerably with particle shape, orientation with the flow, Reynolds number and packing fraction. In this work, the CFD-DEM approach is extended to model a laboratory scale fluidized bed of spherocylinder (rod-like) particles. These rod-like particles can be classified as Geldart D particles and have an aspect ratio of 4. Experiments are performed to study the particle flow behavior in a quasi-2D fluidized bed. Numerically obtained results for pressure drop and bed height are compared with experiments. The capability of CFD-DEM approach to efficiently describe the global bed dynamics for fluidized bed of rod-like particles is demonstrated.

Modeling shear-induced particle ordering and deformation in a dense soft particle suspension

NASA Astrophysics Data System (ADS)

Liao, Chih-Tang; Wu, Yi-Fan; Chien, Wei; Huang, Jung-Ren; Chen, Yeng-Long

2017-11-01

We apply the lattice Boltzmann method and the bead-spring network model of deformable particles (DPs) to study shear-induced particle ordering and deformation and the corresponding rheological behavior for dense DP suspensions confined in a narrow gap under steady external shear. The particle configuration is characterized with small-angle scattering intensity, the real-space 2D local order parameter, and the particle shape factors including deformation, stretching and tilt angles. We investigate how particle ordering and deformation vary with the particle volume fraction ϕ (=0.45-0.65) and the external shear rate characterized with the capillary number Ca (=0.003-0.191). The degree of particle deformation increases mildly with ϕ but significantly with Ca. Under moderate shear rate (Ca  =  0.105), the inter-particle structure evolves from string-like ordering to layered hexagonal close packing (HCP) as ϕ increases. A long wavelength particle slithering motion emerges for sufficiently large ϕ. For ϕ  =  0.61, the structure maintains layered HCP for Ca  =  0.031-0.143 but gradually becomes disordered for larger and smaller Ca. The correlation in particle zigzag movements depends sensitively on ϕ and particle ordering. Layer-by-layer analysis reveals how the non-slippery hard walls affect particle ordering and deformation. The shear-induced reconfiguration of DPs observed in the simulation agrees qualitatively with experimental results of sheared uniform emulsions. The apparent suspension viscosity increases with ϕ but exhibits much weaker dependence compared to hard-sphere suspensions, indicating that particle deformation and unjamming under shear can significantly reduce the viscous stress. Furthermore, the suspension shear-thins, corresponding to increased inter-DP ordering and particle deformation with Ca. This work provides useful insights into the microstructure-rheology relationship of concentrated deformable particle suspensions.

Modeling shear-induced particle ordering and deformation in a dense soft particle suspension.

PubMed

Liao, Chih-Tang; Wu, Yi-Fan; Chien, Wei; Huang, Jung-Ren; Chen, Yeng-Long

2017-11-01

We apply the lattice Boltzmann method and the bead-spring network model of deformable particles (DPs) to study shear-induced particle ordering and deformation and the corresponding rheological behavior for dense DP suspensions confined in a narrow gap under steady external shear. The particle configuration is characterized with small-angle scattering intensity, the real-space 2D local order parameter, and the particle shape factors including deformation, stretching and tilt angles. We investigate how particle ordering and deformation vary with the particle volume fraction ϕ (=0.45-0.65) and the external shear rate characterized with the capillary number Ca (=0.003-0.191). The degree of particle deformation increases mildly with ϕ but significantly with Ca. Under moderate shear rate (Ca  =  0.105), the inter-particle structure evolves from string-like ordering to layered hexagonal close packing (HCP) as ϕ increases. A long wavelength particle slithering motion emerges for sufficiently large ϕ. For ϕ  =  0.61, the structure maintains layered HCP for Ca  =  0.031-0.143 but gradually becomes disordered for larger and smaller Ca. The correlation in particle zigzag movements depends sensitively on ϕ and particle ordering. Layer-by-layer analysis reveals how the non-slippery hard walls affect particle ordering and deformation. The shear-induced reconfiguration of DPs observed in the simulation agrees qualitatively with experimental results of sheared uniform emulsions. The apparent suspension viscosity increases with ϕ but exhibits much weaker dependence compared to hard-sphere suspensions, indicating that particle deformation and unjamming under shear can significantly reduce the viscous stress. Furthermore, the suspension shear-thins, corresponding to increased inter-DP ordering and particle deformation with Ca. This work provides useful insights into the microstructure-rheology relationship of concentrated deformable particle suspensions.

Accelerated simulation of stochastic particle removal processes in particle-resolved aerosol models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Curtis, J.H.; Michelotti, M.D.; Riemer, N.

2016-10-01

Stochastic particle-resolved methods have proven useful for simulating multi-dimensional systems such as composition-resolved aerosol size distributions. While particle-resolved methods have substantial benefits for highly detailed simulations, these techniques suffer from high computational cost, motivating efforts to improve their algorithmic efficiency. Here we formulate an algorithm for accelerating particle removal processes by aggregating particles of similar size into bins. We present the Binned Algorithm for particle removal processes and analyze its performance with application to the atmospherically relevant process of aerosol dry deposition. We show that the Binned Algorithm can dramatically improve the efficiency of particle removals, particularly for low removalmore » rates, and that computational cost is reduced without introducing additional error. In simulations of aerosol particle removal by dry deposition in atmospherically relevant conditions, we demonstrate about 50-times increase in algorithm efficiency.« less

Charged-particle emission tomography

PubMed Central

Ding, Yijun; Caucci, Luca; Barrett, Harrison H.

2018-01-01

Purpose Conventional charged-particle imaging techniques —such as autoradiography —provide only two-dimensional (2D) black ex vivo images of thin tissue slices. In order to get volumetric information, images of multiple thin slices are stacked. This process is time consuming and prone to distortions, as registration of 2D images is required. We propose a direct three-dimensional (3D) autoradiography technique, which we call charged-particle emission tomography (CPET). This 3D imaging technique enables imaging of thick tissue sections, thus increasing laboratory throughput and eliminating distortions due to registration. CPET also has the potential to enable in vivo charged-particle imaging with a window chamber or an endoscope. Methods Our approach to charged-particle emission tomography uses particle-processing detectors (PPDs) to estimate attributes of each detected particle. The attributes we estimate include location, direction of propagation, and/or the energy deposited in the detector. Estimated attributes are then fed into a reconstruction algorithm to reconstruct the 3D distribution of charged-particle-emitting radionuclides. Several setups to realize PPDs are designed. Reconstruction algorithms for CPET are developed. Results Reconstruction results from simulated data showed that a PPD enables CPET if the PPD measures more attributes than just the position from each detected particle. Experiments showed that a two-foil charged-particle detector is able to measure the position and direction of incident alpha particles. Conclusions We proposed a new volumetric imaging technique for charged-particle-emitting radionuclides, which we have called charged-particle emission tomography (CPET). We also proposed a new class of charged-particle detectors, which we have called particle-processing detectors (PPDs). When a PPD is used to measure the direction and/or energy attributes along with the position attributes, CPET is feasible. PMID:28370094

Charged-particle emission tomography.

PubMed

Ding, Yijun; Caucci, Luca; Barrett, Harrison H

2017-06-01

Conventional charged-particle imaging techniques - such as autoradiography - provide only two-dimensional (2D) black ex vivo images of thin tissue slices. In order to get volumetric information, images of multiple thin slices are stacked. This process is time consuming and prone to distortions, as registration of 2D images is required. We propose a direct three-dimensional (3D) autoradiography technique, which we call charged-particle emission tomography (CPET). This 3D imaging technique enables imaging of thick tissue sections, thus increasing laboratory throughput and eliminating distortions due to registration. CPET also has the potential to enable in vivo charged-particle imaging with a window chamber or an endoscope. Our approach to charged-particle emission tomography uses particle-processing detectors (PPDs) to estimate attributes of each detected particle. The attributes we estimate include location, direction of propagation, and/or the energy deposited in the detector. Estimated attributes are then fed into a reconstruction algorithm to reconstruct the 3D distribution of charged-particle-emitting radionuclides. Several setups to realize PPDs are designed. Reconstruction algorithms for CPET are developed. Reconstruction results from simulated data showed that a PPD enables CPET if the PPD measures more attributes than just the position from each detected particle. Experiments showed that a two-foil charged-particle detector is able to measure the position and direction of incident alpha particles. We proposed a new volumetric imaging technique for charged-particle-emitting radionuclides, which we have called charged-particle emission tomography (CPET). We also proposed a new class of charged-particle detectors, which we have called particle-processing detectors (PPDs). When a PPD is used to measure the direction and/or energy attributes along with the position attributes, CPET is feasible. © 2017 The Authors. Medical Physics published by Wiley Periodicals

Particle Swarm Optimization

NASA Technical Reports Server (NTRS)

Venter, Gerhard; Sobieszczanski-Sobieski Jaroslaw

2002-01-01

The purpose of this paper is to show how the search algorithm known as particle swarm optimization performs. Here, particle swarm optimization is applied to structural design problems, but the method has a much wider range of possible applications. The paper's new contributions are improvements to the particle swarm optimization algorithm and conclusions and recommendations as to the utility of the algorithm, Results of numerical experiments for both continuous and discrete applications are presented in the paper. The results indicate that the particle swarm optimization algorithm does locate the constrained minimum design in continuous applications with very good precision, albeit at a much higher computational cost than that of a typical gradient based optimizer. However, the true potential of particle swarm optimization is primarily in applications with discrete and/or discontinuous functions and variables. Additionally, particle swarm optimization has the potential of efficient computation with very large numbers of concurrently operating processors.

Particle Data Group - Downloads

Science.gov Websites

1977 1976 1975 1974 1973 1972 1971 Older Publications Review of Particle Properties 1970 Aug. Review of Particle Properties 1970 Jan. Review of Particle Properties 1969 Review of Particle Properties 1968 Aug

Removal of organic dyes using Cr-containing activated carbon prepared from leather waste.

PubMed

Oliveira, Luiz C A; Coura, Camila Van Zanten; Guimarães, Iara R; Gonçalves, Maraisa

2011-09-15

In this work, hydrogen peroxide decomposition and oxidation of organics in aqueous medium were studied in the presence of activated carbon prepared from wet blue leather waste. The wet blue leather waste, after controlled pyrolysis under CO(2) flow, was transformed into chromium-containing activated carbons. The carbon with Cr showed high microporous surface area (up to 889 m(2)g(-1)). Moreover, the obtained carbon was impregnated with nanoparticles of chromium oxide from the wet blue leather. The chromium oxide was nanodispersed on the activated carbon, and the particle size increased with the activation time. It is proposed that these chromium species on the carbon can activate H(2)O(2) to generate HO radicals, which can lead to two competitive reactions, i.e. the hydrogen peroxide decomposition or the oxidation of organics in water. In fact, in this work we observed that activated carbon obtained from leather waste presented high removal of methylene blue dye combining the adsorption and oxidation processes. Copyright © 2011 Elsevier B.V. All rights reserved.

Nanosystems in Edible Coatings: A Novel Strategy for Food Preservation.

PubMed

Zambrano-Zaragoza, María L; González-Reza, Ricardo; Mendoza-Muñoz, Néstor; Miranda-Linares, Verónica; Bernal-Couoh, Tania F; Mendoza-Elvira, Susana; Quintanar-Guerrero, David

2018-03-01

Currently, nanotechnology represents an important tool and an efficient option for extending the shelf life of foods. Reducing particle size to nanometric scale gives materials distinct and improved properties compared to larger systems. For food applications, this technology allows the incorporation of hydrophilic and lipophilic substances with antimicrobial and antioxidant properties that can be released during storage periods to increase the shelf life of diverse products, including whole and fresh-cut fruits and vegetables, nuts, seeds, and cheese, among others. Edible coatings are usually prepared with natural polymers that are non-toxic, economical, and readily available. Nanosystems, in contrast, may also be prepared with biodegradable synthetic polymers, and liquid and solid lipids at room temperature. In this review, recent developments in the use of such nanosystems as nanoparticles, nanotubes, nanocomposites, and nanoemulsions, are discussed critically. The use of polymers as the support matrix for nanodispersions to form edible coatings for food preservation is also analyzed, but the central purpose of the article is to describe available information on nanosystems and their use in different food substrates to help formulators in their work.

Improving the anticancer activity of curcumin using nanocurcumin dispersion in water.

PubMed

Basniwal, Rupesh Kumar; Khosla, Ritu; Jain, Nidhi

2014-01-01

Curcumin is a highly potent, nontoxic bioactive agent found in turmeric and is known to have significant anticancer properties against different types of cancer cells. The major disadvantage associated with the use of curcumin, however, is its low systemic bioavailability due to its poor aqueous solubility. The focus of the present study was to generate nanoparticles of curcumin with improved aqueous phase solubility, and to investigate their efficacy in treating cancer cells. Curcumin nanoparticles having particle size in the range 2-40 nm and aqueous solubility of up to a maximum of 3 mg/mL were prepared. Evaluation of anticancer properties of curcumin nanodispersion was carried out in 3 different cancer cell lines: lung (A549), liver (HepG2), and skin (A431). The results demonstrated that under aqueous conditions curcumin nanoparticles exhibited similar or a much stronger antiproliferative effect on the cancer cells compared to normal curcumin in DMSO. Our results lead way toward unharnessed potential of curcumin in the form of its nanoparticles as an adjuvant therapy for clinical application in treating various cancers.

Multiscale modeling of particle in suspension with smoothed dissipative particle dynamics

NASA Astrophysics Data System (ADS)

Bian, Xin; Litvinov, Sergey; Qian, Rui; Ellero, Marco; Adams, Nikolaus A.

2012-01-01

We apply smoothed dissipative particle dynamics (SDPD) [Español and Revenga, Phys. Rev. E 67, 026705 (2003)] to model solid particles in suspension. SDPD is a thermodynamically consistent version of smoothed particle hydrodynamics (SPH) and can be interpreted as a multiscale particle framework linking the macroscopic SPH to the mesoscopic dissipative particle dynamics (DPD) method. Rigid structures of arbitrary shape embedded in the fluid are modeled by frozen particles on which artificial velocities are assigned in order to satisfy exactly the no-slip boundary condition on the solid-liquid interface. The dynamics of the rigid structures is decoupled from the solvent by solving extra equations for the rigid body translational/angular velocities derived from the total drag/torque exerted by the surrounding liquid. The correct scaling of the SDPD thermal fluctuations with the fluid-particle size allows us to describe the behavior of the particle suspension on spatial scales ranging continuously from the diffusion-dominated regime typical of sub-micron-sized objects towards the non-Brownian regime characterizing macro-continuum flow conditions. Extensive tests of the method are performed for the case of two/three dimensional bulk particle-system both in Brownian/ non-Brownian environment showing numerical convergence and excellent agreement with analytical theories. Finally, to illustrate the ability of the model to couple with external boundary geometries, the effect of confinement on the diffusional properties of a single sphere within a micro-channel is considered, and the dependence of the diffusion coefficient on the wall-separation distance is evaluated and compared with available analytical results.

Compact particle accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elizondo-Decanini, Juan M.

2017-08-29

A compact particle accelerator having an input portion configured to receive power to produce particles for acceleration, where the input portion includes a switch, is provided. In a general embodiment, a vacuum tube receives particles produced from the input portion at a first end, and a plurality of wafer stacks are positioned serially along the vacuum tube. Each of the plurality of wafer stacks include a dielectric and metal-oxide pair, wherein each of the plurality of wafer stacks further accelerate the particles in the vacuum tube. A beam shaper coupled to a second end of the vacuum tube shapes themore » particles accelerated by the plurality of wafer stacks into a beam and an output portion outputs the beam.« less

Particle Analysis Pitfalls

NASA Technical Reports Server (NTRS)

Hughes, David; Dazzo, Tony

2007-01-01

This viewgraph presentation reviews the use of particle analysis to assist in preparing for the 4th Hubble Space Telescope (HST) Servicing mission. During this mission the Space Telescope Imaging Spectrograph (STIS) will be repaired. The particle analysis consisted of Finite element mesh creation, Black-body viewfactors generated using I-DEAS TMG Thermal Analysis, Grey-body viewfactors calculated using Markov method, Particle distribution modeled using an iterative Monte Carlo process, (time-consuming); in house software called MASTRAM, Differential analysis performed in Excel, and Visualization provided by Tecplot and I-DEAS. Several tests were performed and are reviewed: Conformal Coat Particle Study, Card Extraction Study, Cover Fastener Removal Particle Generation Study, and E-Graf Vibration Particulate Study. The lessons learned during this analysis are also reviewed.

Apparatus for measuring particle properties

DOEpatents

Rader, D.J.; Castaneda, J.N.; Grasser, T.W.; Brockmann, J.E.

1998-08-11

An apparatus is described for determining particle properties from detected light scattered by the particles. The apparatus uses a light beam with novel intensity characteristics to discriminate between particles that pass through the beam and those that pass through an edge of the beam. The apparatus can also discriminate between light scattered by one particle and light scattered by multiple particles. The particle`s size can be determined from the intensity of the light scattered. The particle`s velocity can be determined from the elapsed time between various intensities of the light scattered. 11 figs.

Particle-induced viscous fingering

NASA Astrophysics Data System (ADS)

Lee, Sungyon

2017-11-01

An inclusion of non-colloidal particles in a Newtonian liquid can fundamentally change the interfacial dynamics and even cause interfacial instabilities. In this talk, we report a particle-induced fingering instability when a mixture of particles and viscous oil is injected radially into a Hele-Shaw cell. Our experimental results show that the onset and characteristics of fingering are most directly affected by the particle volume fraction but also depend on the ratio of the particle diameter to gap size. In particular, the formation of a particle band is observed on the interface only when the particle diameter is comparable to the channel gap thickness. This work demonstrates the complex coupling between suspensions and fluid-fluid interfaces and has broad relevance in suspension processing, particle self-assembly, and oil recovery processes. The physical mechanism behind the instability and a quantitative model are also discussed.

Preparation of silica-coated poly(styrene-co-4-vinylpyridine) particles and hollow particles.

PubMed

Zou, Hua; Wu, Shishan; Shen, Jian

2008-09-16

This paper presents a novel method for preparation of polymer-silica colloidal nanocomposites based on emulsion polymerization and subsequent sol-gel nanocoating process. The polystyrene latex particles bearing basic groups on their surfaces were successfully synthesized through emulsion polymerization using 4-vinylpyridine (4VP) as a functional comonomer and polyvinylpyrrolidone (PVP) as a surfactant. A series of poly(styrene-co-4-vinylpyridine)/SiO2 nanocomposite particles with smooth or rough core-shell morphology were obtained through the coating process. The poly(styrene-co-4-vinylpyridine) particles could be dissolved subsequently or simultaneously during the sol-gel coating process to form hollow particles. The effects of the amount of 4VP, PVP, NH(4)OH, and tetraethoxysilane (TEOS) on both the nanocomposite particles and hollow particles were investigated. Transmission electron microscopy showed that the morphology of the nanocomposite particles and hollow particles was strongly influenced by the initial feed of the comonomer 4VP and the coupling agent PVP. The conditions to obtain all hollow particles were also studied. Thermogravimetric analysis and energy dispersive X-ray spectroscopy analyses indicated that the interiors of hollow particles were not really "hollow".

Fuzzy Logic Particle Tracking

NASA Technical Reports Server (NTRS)

2005-01-01

A new all-electronic Particle Image Velocimetry technique that can efficiently map high speed gas flows has been developed in-house at the NASA Lewis Research Center. Particle Image Velocimetry is an optical technique for measuring the instantaneous two component velocity field across a planar region of a seeded flow field. A pulsed laser light sheet is used to illuminate the seed particles entrained in the flow field at two instances in time. One or more charged coupled device (CCD) cameras can be used to record the instantaneous positions of particles. Using the time between light sheet pulses and determining either the individual particle displacements or the average displacement of particles over a small subregion of the recorded image enables the calculation of the fluid velocity. Fuzzy logic minimizes the required operator intervention in identifying particles and computing velocity. Using two cameras that have the same view of the illumination plane yields two single exposure image frames. Two competing techniques that yield unambiguous velocity vector direction information have been widely used for reducing the single-exposure, multiple image frame data: (1) cross-correlation and (2) particle tracking. Correlation techniques yield averaged velocity estimates over subregions of the flow, whereas particle tracking techniques give individual particle velocity estimates. For the correlation technique, the correlation peak corresponding to the average displacement of particles across the subregion must be identified. Noise on the images and particle dropout result in misidentification of the true correlation peak. The subsequent velocity vector maps contain spurious vectors where the displacement peaks have been improperly identified. Typically these spurious vectors are replaced by a weighted average of the neighboring vectors, thereby decreasing the independence of the measurements. In this work, fuzzy logic techniques are used to determine the true

Method of particle trajectory recognition in particle flows of high particle concentration using a candidate trajectory tree process with variable search areas

DOEpatents

Shaffer, Franklin D.

2013-03-12

The application relates to particle trajectory recognition from a Centroid Population comprised of Centroids having an (x, y, t) or (x, y, f) coordinate. The method is applicable to visualization and measurement of particle flow fields of high particle. In one embodiment, the centroids are generated from particle images recorded on camera frames. The application encompasses digital computer systems and distribution mediums implementing the method disclosed and is particularly applicable to recognizing trajectories of particles in particle flows of high particle concentration. The method accomplishes trajectory recognition by forming Candidate Trajectory Trees and repeated searches at varying Search Velocities, such that initial search areas are set to a minimum size in order to recognize only the slowest, least accelerating particles which produce higher local concentrations. When a trajectory is recognized, the centroids in that trajectory are removed from consideration in future searches.

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

DOEpatents

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.

Interactive Terascale Particle Visualization

NASA Technical Reports Server (NTRS)

Ellsworth, David; Green, Bryan; Moran, Patrick

2004-01-01

This paper describes the methods used to produce an interactive visualization of a 2 TB computational fluid dynamics (CFD) data set using particle tracing (streaklines). We use the method introduced by Bruckschen et al. [2001] that pre-computes a large number of particles, stores them on disk using a space-filling curve ordering that minimizes seeks, and then retrieves and displays the particles according to the user's command. We describe how the particle computation can be performed using a PC cluster, how the algorithm can be adapted to work with a multi-block curvilinear mesh, and how the out-of-core visualization can be scaled to 296 billion particles while still achieving interactive performance on PG hardware. Compared to the earlier work, our data set size and total number of particles are an order of magnitude larger. We also describe a new compression technique that allows the lossless compression of the particles by 41% and speeds the particle retrieval by about 30%.

Small particles big effect? - Investigating ice nucleation abilities of soot particles

NASA Astrophysics Data System (ADS)

Mahrt, Fabian; David, Robert O.; Lohmann, Ulrike; Stopford, Chris; Wu, Zhijun; Kanji, Zamin A.

2017-04-01

Atmospheric soot particles are primary particles produced by incomplete combustion of biomass and/or fossil fuels. Thus soot mainly originates from anthropogenic emissions, stemming from combustion related processes in transport vehicles, industrial and residential uses. Such soot particles are generally complex mixtures of black carbon (BC) and organic matter (OM) (Bond et al., 2013; Petzold et al., 2013), depending on the sources and the interaction of the primary particles with other atmospheric matter and/or gases BC absorbs solar radiation having a warming effect on global climate. It can also act as a heterogeneous ice nucleating particle (INP) and thus impact cloud-radiation interactions, potentially cooling the climate (Lohmann, 2002). Previous studies, however, have shown conflicting results concerning the ice nucleation ability of soot, limiting the ability to predict its effects on Earth's radiation budget. Here we present a laboratory study where we systematically investigate the ice nucleation behavior of different soot particles. Commercial soot samples are used, including an amorphous, industrial carbon frequently used in coatings and coloring (FW 200, Orion Engineered Carbons) and a fullerene soot (572497 ALDRICH), e.g. used as catalyst. In addition, we use soot generated from a propane flame Combustion Aerosol Standard Generator (miniCAST, JING AG), as a proxy for atmospheric soot particles. The ice nucleation ability of these soot types is tested on size-selected particles for a wide temperature range from 253 K to 218 K, using the Horizontal Ice Nucleation Chamber (HINC), a Continuous Flow Diffusion Chamber (CFDC) (Kanji and Abbatt, 2009). Ice nucleation results from these soot surrogates will be compared to chemically more complex real world samples, collected on filters. Filters will be collected during the 2016/2017 winter haze periods in Beijing, China and represent atmospheric soot particles with sources from both industrial and residential

Small and large particle limits of single scattering albedo for homogeneous, spherical particles

NASA Astrophysics Data System (ADS)

Moosmüller, H.; Sorensen, C. M.

2018-01-01

The aerosol single scattering albedo (SSA) is the dominant intensive particle parameter determining aerosols direct radiative forcing. For homogeneous spherical particles and a complex refractive index independent of wavelength, the SSA is solely dependent on size parameter (ratio of particle circumference and wavelength) and complex refractive index of the particle. Here, we explore this dependency for the small and large particle limits with size parameters much smaller and much larger than one. We show that in the small particle limit of Rayleigh scattering, a novel, generalized size parameter can be introduced that unifies the SSA dependence on particle size parameter independent of complex refractive index. In the large particle limit, SSA decreases with increasing product of imaginary part of the refractive index and size parameter, another generalized parameter, until this product becomes about one, then stays fairly constant until the imaginary part of the refractive index becomes comparable with the real part minus one. Beyond this point, particles start to acquire metallic character and SSA quickly increases with the imaginary part of the refractive index and approaches one.

Source apportionment of lead-containing aerosol particles in Shanghai using single particle mass spectrometry.

PubMed

Zhang, Yaping; Wang, Xiaofei; Chen, Hong; Yang, Xin; Chen, Jianmin; Allen, Jonathan O

2009-01-01

Lead (Pb) in individual aerosol particles was measured using single particle aerosol mass spectrometer (ATOFMS) in the summer of 2007 in Shanghai, China. Pb was found in 3% of particles with diameters in the range 0.1-2.0 microm. Single particle data were analyzed focusing on the particles with high Pb content which were mostly submicron. Using the ART-2a neural network algorithm, these fine Pb-rich particles were classified into eight main classes by their mass spectral patterns. Based on the size distribution, temporal variation of number density, chemical composition and the correlation between different chemical species for each class, three major emission sources were identified. About 45% of the Pb-rich particles contained organic or elemental carbon and were attributed to the emission from coal combustion; particles with good correlation between Cl and Pb content were mostly attributed to waste incineration. One unique class of particles was identified by strong phosphate and Pb signals, which were assigned to emissions from phosphate industry. Other Pb-rich particles included aged sea salt and particles from metallurgical processes.

Effect of particle-particle interactions on the acoustic radiation force in an ultrasonic standing wave

NASA Astrophysics Data System (ADS)

Lipkens, Bart; Ilinskii, Yurii A.; Zabolotskaya, Evgenia A.

2015-10-01

Ultrasonic standing waves are widely used for separation applications. In MEMS applications, a half wavelength standing wave field is generated perpendicular to a laminar flow. The acoustic radiation force exerted on the particle drives the particle to the center of the MEMS channel, where concentrated particles are harvested. In macro-scale applications, the ultrasonic standing wave spans multiple wavelengths. Examples of such applications are oil/water emulsion splitting [1], and blood/lipid separation [2]. In macro-scale applications, particles are typically trapped in the standing wave, resulting in clumping or coalescence of particles/droplets. Subsequent gravitational settling results in separation of the secondary phase. An often used expression for the radiation force on a particle is that derived by Gorkov [3]. The assumptions are that the particle size is small relative to the wavelength, and therefore, only monopole and dipole scattering contributions are used to calculate the radiation force. This framework seems satisfactory for MEMS scale applications where each particle is treated separately by the standing wave, and concentrations are typically low. In macro-scale applications, particle concentration is high, and particle clumping or droplet coalescence results in particle sizes not necessarily small relative to the wavelength. Ilinskii et al. developed a framework for calculation of the acoustic radiation force valid for any size particle [4]. However, this model does not take into account particle to particle effects, which can become important as particle concentration increases. It is known that an acoustic radiation force on a particle or a droplet is determined by the local field. An acoustic radiation force expression is developed that includes the effect of particle to particle interaction. The case of two neighboring particles is considered. The approach is based on sound scattering by the particles. The acoustic field at the location of

Effect of particle-particle interactions on the acoustic radiation force in an ultrasonic standing wave

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lipkens, Bart, E-mail: blipkens@wne.edu; Ilinskii, Yurii A., E-mail: ilinskii@gmail.com; Zabolotskaya, Evgenia A., E-mail: zheniazabolotskaya@gmail.com

Ultrasonic standing waves are widely used for separation applications. In MEMS applications, a half wavelength standing wave field is generated perpendicular to a laminar flow. The acoustic radiation force exerted on the particle drives the particle to the center of the MEMS channel, where concentrated particles are harvested. In macro-scale applications, the ultrasonic standing wave spans multiple wavelengths. Examples of such applications are oil/water emulsion splitting [1], and blood/lipid separation [2]. In macro-scale applications, particles are typically trapped in the standing wave, resulting in clumping or coalescence of particles/droplets. Subsequent gravitational settling results in separation of the secondary phase. Anmore » often used expression for the radiation force on a particle is that derived by Gorkov [3]. The assumptions are that the particle size is small relative to the wavelength, and therefore, only monopole and dipole scattering contributions are used to calculate the radiation force. This framework seems satisfactory for MEMS scale applications where each particle is treated separately by the standing wave, and concentrations are typically low. In macro-scale applications, particle concentration is high, and particle clumping or droplet coalescence results in particle sizes not necessarily small relative to the wavelength. Ilinskii et al. developed a framework for calculation of the acoustic radiation force valid for any size particle [4]. However, this model does not take into account particle to particle effects, which can become important as particle concentration increases. It is known that an acoustic radiation force on a particle or a droplet is determined by the local field. An acoustic radiation force expression is developed that includes the effect of particle to particle interaction. The case of two neighboring particles is considered. The approach is based on sound scattering by the particles. The acoustic field at the

Ion beam synthesis of Fe nanoparticles in MgO and yttria-stabilized zirconia

NASA Astrophysics Data System (ADS)

Potzger, K.; Reuther, H.; Zhou, Shengqiang; Mücklich, A.; Grötzschel, R.; Eichhorn, F.; Liedke, M. O.; Fassbender, J.; Lichte, H.; Lenk, A.

2006-04-01

To form embedded Fe nanoparticles, MgO(001) and YSZ(001) single crystals have been implanted at elevated temperatures with Fe ions at energies of 100 keV and 110 keV, respectively. The ion fluence was fixed at 6×1016 cm-2. As a result, γ- and α-phase Fe nanoparticles were synthesized inside MgO and YSZ, respectively. A synthesis efficiency of 100% has been achieved for implantation at 1273 K into YSZ. The ferromagnetic behavior of the α-Fe nanoparticles is reflected by a magnetic hyperfine field of 330 kOe and a hysteretic magnetization reversal. Electron holography showed a fringing magnetic field around some, but not all of the particles.

System for forming janus particles

DOEpatents

Hong, Liang [Midland, MI; Jiang, Shan [Champaign, IL; Granick, Steve [Champaign, IL

2011-01-25

The invention is a method of forming Janus particles, that includes forming an emulsion that contains initial particles, a first liquid, and a second liquid; solidifying the first liquid to form a solid that contains at least a portion of the initial particles on a surface of the solid; and treating the exposed particle sides with a first surface modifying agent, to form the Janus particles. Each of the initial particles on the surface has an exposed particle side and a blocked particle side.

Single particle mass spectral signatures from vehicle exhaust particles and the source apportionment of on-line PM2.5 by single particle aerosol mass spectrometry.

PubMed

Yang, Jian; Ma, Shexia; Gao, Bo; Li, Xiaoying; Zhang, Yanjun; Cai, Jing; Li, Mei; Yao, Ling'ai; Huang, Bo; Zheng, Mei

2017-09-01

In order to accurately apportion the many distinct types of individual particles observed, it is necessary to characterize fingerprints of individual particles emitted directly from known sources. In this study, single particle mass spectral signatures from vehicle exhaust particles in a tunnel were performed. These data were used to evaluate particle signatures in a real-world PM 2.5 apportionment study. The dominant chemical type originating from average positive and negative mass spectra for vehicle exhaust particles are EC species. Four distinct particle types describe the majority of particles emitted by vehicle exhaust particles in this tunnel. Each particle class is labeled according to the most significant chemical features in both average positive and negative mass spectral signatures, including ECOC, NaK, Metal and PAHs species. A single particle aerosol mass spectrometry (SPAMS) was also employed during the winter of 2013 in Guangzhou to determine both the size and chemical composition of individual atmospheric particles, with vacuum aerodynamic diameter (d va ) in the size range of 0.2-2μm. A total of 487,570 particles were chemically analyzed with positive and negative ion mass spectra and a large set of single particle mass spectra was collected and analyzed in order to identify the speciation. According to the typical tracer ions from different source types and classification by the ART-2a algorithm which uses source fingerprints for apportioning ambient particles, the major sources of single particles were simulated. Coal combustion, vehicle exhaust, and secondary ion were the most abundant particle sources, contributing 28.5%, 17.8%, and 18.2%, respectively. The fraction with vehicle exhaust species particles decreased slightly with particle size in the condensation mode particles. Copyright © 2017 Elsevier B.V. All rights reserved.

Forces on a segregating particle

NASA Astrophysics Data System (ADS)

Lueptow, Richard M.; Shankar, Adithya; Fry, Alexander M.; Ottino, Julio M.; Umbanhowar, Paul B.

2017-11-01

Size segregation in flowing granular materials is not well understood at the particle level. In this study, we perform a series of 3D Discrete Element Method (DEM) simulations to measure the segregation force on a single spherical test particle tethered to a spring in the vertical direction in a shearing bed of particles with gravity acting perpendicular to the shear. The test particle is the same size or larger than the bed particles. At equilibrium, the downward spring force and test particle weight are offset by the upward buoyancy-like force and a size ratio dependent force. We find that the buoyancy-like force depends on the bed particle density and the Voronoi volume occupied by the test particle. By changing the density of the test particle with the particle size ratio such that the buoyancy force matches the test particle weight, we show that the upward size segregation force is a quadratic function of the particle size ratio. Based on this, we report an expression for the net force on a single particle as the sum of a size ratio dependent force, a buoyancy-like force, and the weight of the particle. Supported by NSF Grant CBET-1511450 and the Procter and Gamble Company.

Merging for Particle-Mesh Complex Particle Kinetic Modeling of the Multiple Plasma Beams

NASA Technical Reports Server (NTRS)

Lipatov, Alexander S.

2011-01-01

We suggest a merging procedure for the Particle-Mesh Complex Particle Kinetic (PMCPK) method in case of inter-penetrating flow (multiple plasma beams). We examine the standard particle-in-cell (PIC) and the PMCPK methods in the case of particle acceleration by shock surfing for a wide range of the control numerical parameters. The plasma dynamics is described by a hybrid (particle-ion-fluid-electron) model. Note that one may need a mesh if modeling with the computation of an electromagnetic field. Our calculations use specified, time-independent electromagnetic fields for the shock, rather than self-consistently generated fields. While a particle-mesh method is a well-verified approach, the CPK method seems to be a good approach for multiscale modeling that includes multiple regions with various particle/fluid plasma behavior. However, the CPK method is still in need of a verification for studying the basic plasma phenomena: particle heating and acceleration by collisionless shocks, magnetic field reconnection, beam dynamics, etc.

Vaporizing particle velocimeter

NASA Technical Reports Server (NTRS)

Weinstein, Leonard M. (Inventor)

1992-01-01

A velocimeter measures flow characteristics of a flow traveling through a chamber in a given direction. Tracer particles are entrained in the flow and a source of radiant energy produces an output stream directed transversely to the chamber, having a sufficient intensity to vaporize the particles as they pass through the output stream. Each of the vaporized particles explodes to produce a shock wave and a hot core, and a flow visualization system tracks the motion of the hot cores and shock waves to measure the velocity of each tracer particle and the temperature of the flow around the tracer.

Bioactivation of particles

DOEpatents

Pinaud, Fabien [Berkeley, CA; King, David [San Francisco, CA; Weiss, Shimon [Los Angeles, CA

2011-08-16

Particles are bioactivated by attaching bioactivation peptides to the particle surface. The bioactivation peptides are peptide-based compounds that impart one or more biologically important functions to the particles. Each bioactivation peptide includes a molecular or surface recognition part that binds with the surface of the particle and one or more functional parts. The surface recognition part includes an amino-end and a carboxy-end and is composed of one or more hydrophobic spacers and one or more binding clusters. The functional part(s) is attached to the surface recognition part at the amino-end and/or said carboxy-end.

Sol–gel dip coating of yttria-stabilized tetragonal zirconia dental ceramic by aluminosilicate nanocomposite as a novel technique to improve the bonding of veneering porcelain

PubMed Central

Madani, Azamsadat; Nakhaei, Mohammadreza; Karami, Parisa; Rajabzadeh, Ghadir; Salehi, Sahar; Bagheri, Hossein

2016-01-01

The aim of this in vitro study was to evaluate the effect of silica and aluminosilicate nanocomposite coating of zirconia-based dental ceramic by a sol–gel dip-coating technique on the bond strength of veneering porcelain to the yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in vitro. Thirty Y-TZP blocks (10 mm ×10 mm ×3 mm) were prepared and were assigned to four experimental groups (n=10/group): C, without any further surface treatment as the control group; S, sandblasted using 110 μm alumina powder; Si, silica sol dip coating + calcination; and Si/Al, aluminosilicate sol dip coating + calcination. After preparing Y-TZP samples, a 3 mm thick layer of the recommended porcelain was fired on the coated Y-TZP surface. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis were used to characterize the coating and the nature of the bonding between the coating and zirconia. To examine the zirconia–porcelain bond strength, a microtensile bond strength (μTBS) approach was chosen. FT-IR study showed the formation of silica and aluminosilicate materials. XRD pattern showed the formation of new phases consisting of Si, Al, and Zr in coated samples. SEM showed the formation of a uniform coating on Y-TZP samples. Maximum μTBS values were obtained in aluminosilicate samples, which were significantly increased compared to control and sandblasted groups (P=0.013 and P<0.001, respectively). This study showed that aluminosilicate sol–gel dip coating can be considered as a convenient, less expensive reliable method for improving the bond strength between dental Y-TZP ceramics and veneering porcelain. PMID:27478376

Planar particle/droplet size measurement technique using digital particle image velocimetry image data

NASA Technical Reports Server (NTRS)

Kadambi, Jaikrishnan R. (Inventor); Wernet, Mark P. (Inventor); Mielke, Amy F. (Inventor)

2005-01-01

A method for determining a mass flux of an entrained phase in a planar two-phase flow records images of particles in the two-phase flow. Respective sizes of the particles (the entrained phase) are determined as a function of a separation between spots identified on the particle images. Respective velocities of the particles are determined. The mass flux of the entrained phase is determined as a function of the size and velocity of the particles.

Pileup per particle identification

DOE PAGES

Bertolini, Daniele; Harris, Philip; Low, Matthew; ...

2014-10-09

We propose a new method for pileup mitigation by implementing “pileup per particle identification” (PUPPI). For each particle we first define a local shape α which probes the collinear versus soft diffuse structure in the neighborhood of the particle. The former is indicative of particles originating from the hard scatter and the latter of particles originating from pileup interactions. The distribution of α for charged pileup, assumed as a proxy for all pileup, is used on an event-by-event basis to calculate a weight for each particle. The weights describe the degree to which particles are pileup-like and are used tomore » rescale their four-momenta, superseding the need for jet-based corrections. Furthermore, the algorithm flexibly allows combination with other, possibly experimental, probabilistic information associated with particles such as vertexing and timing performance. We demonstrate the algorithm improves over existing methods by looking at jet p T and jet mass. As a result, we also find an improvement on non-jet quantities like missing transverse energy.« less

CLASHING BEAM PARTICLE ACCELERATOR

DOEpatents

Burleigh, R.J.

1961-04-11

A charged-particle accelerator of the proton synchrotron class having means for simultaneously accelerating two separate contra-rotating particle beams within a single annular magnet structure is reported. The magnet provides two concentric circular field regions of opposite magnetic polarity with one field region being of slightly less diameter than the other. The accelerator includes a deflector means straddling the two particle orbits and acting to collide the two particle beams after each has been accelerated to a desired energy. The deflector has the further property of returning particles which do not undergo collision to the regular orbits whereby the particles recirculate with the possibility of colliding upon subsequent passages through the deflector.

Charged-particle emission tomography

NASA Astrophysics Data System (ADS)

Ding, Yijun

Conventional charged-particle imaging techniques--such as autoradiography-- provide only two-dimensional (2D) images of thin tissue slices. To get volumetric information, images of multiple thin slices are stacked. This process is time consuming and prone to distortions, as registration of 2D images is required. We propose a direct three-dimensional (3D) autoradiography technique, which we call charged-particle emission tomography (CPET). This 3D imaging technique enables imaging of thick sections, thus increasing laboratory throughput and eliminating distortions due to registration. In CPET, molecules or cells of interest are labeled so that they emit charged particles without significant alteration of their biological function. Therefore, by imaging the source of the charged particles, one can gain information about the distribution of the molecules or cells of interest. Two special case of CPET include beta emission tomography (BET) and alpha emission tomography (alphaET), where the charged particles employed are fast electrons and alpha particles, respectively. A crucial component of CPET is the charged-particle detector. Conventional charged-particle detectors are sensitive only to the 2-D positions of the detected particles. We propose a new detector concept, which we call particle-processing detector (PPD). A PPD measures attributes of each detected particle, including location, direction of propagation, and/or the energy deposited in the detector. Reconstruction algorithms for CPET are developed, and reconstruction results from simulated data are presented for both BET and alphaET. The results show that, in addition to position, direction and energy provide valuable information for 3D reconstruction of CPET. Several designs of particle-processing detectors are described. Experimental results for one detector are discussed. With appropriate detector design and careful data analysis, it is possible to measure direction and energy, as well as position of each

Microscale simulations of shock interaction with large assembly of particles for developing point-particle models

NASA Astrophysics Data System (ADS)

Thakur, Siddharth; Neal, Chris; Mehta, Yash; Sridharan, Prasanth; Jackson, Thomas; Balachandar, S.

2017-01-01

Micrsoscale simulations are being conducted for developing point-particle and other related models that are needed for the mesoscale and macroscale simulations of explosive dispersal of particles. These particle models are required to compute (a) instantaneous aerodynamic force on the particle and (b) instantaneous net heat transfer between the particle and the surrounding. A strategy for a sequence of microscale simulations has been devised that allows systematic development of the hybrid surrogate models that are applicable at conditions representative of the explosive dispersal application. The ongoing microscale simulations seek to examine particle force dependence on: (a) Mach number, (b) Reynolds number, and (c) volume fraction (different particle arrangements such as cubic, face-centered cubic (FCC), body-centered cubic (BCC) and random). Future plans include investigation of sequences of fully-resolved microscale simulations consisting of an array of particles subjected to more realistic time-dependent flows that progressively better approximate the actual problem of explosive dispersal. Additionally, effects of particle shape, size, and number in simulation as well as the transient particle deformation dependence on various parameters including: (a) particle material, (b) medium material, (c) multiple particles, (d) incoming shock pressure and speed, (e) medium to particle impedance ratio, (f) particle shape and orientation to shock, etc. are being investigated.

Particle Image Velocimetry Applications Using Fluorescent Dye-Doped Particles

NASA Technical Reports Server (NTRS)

Petrosky, Brian J.; Maisto, Pietro; Lowe, K. Todd; Andre, Matthieu A.; Bardet, Philippe M.; Tiemsin, Patsy I.; Wohl, Christopher J.; Danehy, Paul M.

2015-01-01

Polystyrene latex sphere particles are widely used to seed flows for velocimetry techniques such as Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV). These particles may be doped with fluorescent dyes such that signals spectrally shifted from the incident laser wavelength may be detected via Laser Induced Fluorescence (LIF). An attractive application of the LIF signal is achieving velocimetry in the presence of strong interference from laser scatter, opening up new research possibilities very near solid surfaces or at liquid/gas interfaces. Additionally, LIF signals can be used to tag different fluid streams to study mixing. While fluorescence-based PIV has been performed by many researchers for particles dispersed in water flows, the current work is among the first in applying the technique to micron-scale particles dispersed in a gas. A key requirement for such an application is addressing potential health hazards from fluorescent dyes; successful doping of Kiton Red 620 (KR620) has enabled the use of this relatively safe dye for fluorescence PIV for the first time. In this paper, basic applications proving the concept of PIV using the LIF signal from KR620-doped particles are exhibited for a free jet and a twophase flow apparatus. Results indicate that while the fluorescence PIV techniques are roughly 2 orders of magnitude weaker than Mie scattering, they provide a viable method for obtaining data in flow regions previously inaccessible via standard PIV. These techniques have the potential to also complement Mie scattering signals, for example in multi-stream and/or multi-phase experiments.

Wave-Particle Interactions and Particle Acceleration in Turbulent Plasmas: Hybrid Simulations

NASA Astrophysics Data System (ADS)

Kucharek, Harald; Pogorelov, Nikolai; Mueller, Hans; Gamayunov, Konstantin; Farrugia, Charles

2015-04-01

Wave-particle interactions and acceleration processes are present in all key regions inside and outside of the heliosphere. Spacecraft observations measure ion distributions and accelerated ion populations, which are the result of one or several processes. For instance STEREO measures energetic particles associated with interplanetary discontinuities and in the solar wind. Voyager and IBEX provide unique data of energetic particles from the termination shock and the inner and outer heliopause. The range of plasma conditions covered by observations is enormous. However, the physical processes causing particle acceleration and wave-particle interaction and determining the particle distributions are still unknown. Currently two mechanisms, the so-called pumping mechanism (Fisk and Gloeckler, 2010) and merging/contracting island (Fermo, Drake & Swisdak, 2010) are discussed as promising models. In order to determine these individual processes, numerical models or theoretical considerations are needed. Hybrid simulations, which include all kinetic processes self-consistently on the ion level, are a very proven, powerful tool to investigate wave-particle interaction, turbulence, and phase-space evolution of pickup and solar wind ions. In the framework of this study we performed 3D multi-species hybrid simulations for an ion/ion beam instability to study the temporal evolution of ion distributions, their stability, and the influence of self-generated waves. We investigated the energization of ions downstream of interplanetary discontinuities and shocks and downstream of the termination shock, the turbulence, and growth rate of instabilities and compared the results with theoretical predictions. The simulations show that ions can be accelerated downstream of collisionless shocks by trapping of charged particles in coherent wave fronts.

Durability of zirconia thermal-barrier ceramic coatings on air-cooled turbine blades in cyclic jet engine operation

NASA Technical Reports Server (NTRS)

Liebert, C. H.; Jacobs, R. E.; Stecura, S.; Morse, C. R.

1976-01-01

Thermal barrier ceramic coatings of stabilized zirconia over a bond coat of Ni Cr Al Y were tested for durability on air cooled turbine rotor blades in a research turbojet engine. Zirconia stabilized with either yttria, magnesia, or calcia was investigated. On the basis of durability and processing cost, the yttria stabilized zirconia was considered the best of the three coatings investigated.

The Effect of Particle Size on the Biodistribution of Low-modulus Hydrogel PRINT Particles

PubMed Central

Merkel, Timothy J.; Chen, Kai; Jones, Stephen W.; Pandya, Ashish A.; Tian, Shaomin; Napier, Mary E.; Zamboni, William E.; DeSimone, Joseph M.

2012-01-01

There is a growing recognition that the deformability of particles used for drug delivery plays a significant role on their biodistribution and circulation profile. Understanding these effects would provide a crucial tool for the rational design of drug delivery systems. While particles resembling red blood cells (RBCs) in size, shape and deformability have extended circulation times and altered biodistribution profiles compared to rigid, but otherwise similar particles, the in vivo behavior of such highly deformable particles of varied size has not been explored. We report the fabrication of a series of discoid, monodisperse, low-modulus hydrogel particles with diameters ranging from 0.8 to 8.9 μm, spanning sizes smaller than and larger than RBCs. We injected these particles into healthy mice, and tracked their concentration in the blood and their distribution into major organs. These deformable particles all demonstrated some hold up in filtration tissues like the lungs and spleen, followed by release back into the circulation, characterized by decreases in particles in these tissues with concomitant increases in particle concentration in blood. Particles similar to red blood cells in size demonstrated longer circulation times, suggesting that this size and shape of deformable particle is uniquely suited to avoid clearance. PMID:22705460

How do dairy cows chew?--particle size analysis of selected feeds with different particle length distributions and of respective ingested bolus particles.

PubMed

Schadt, I; Ferguson, J D; Azzaro, G; Petriglieri, R; Caccamo, M; Van Soest, P; Licitra, G

2012-08-01

Not only feed but also respective bolus particle size could alter diet efficiency and cow performance. The objective of this project was to characterize particle size of selected feeds and respective swallowed boli. Feed samples included 6 different particle length rye grass hay samples, 1 grass silage, 1 corn silage, and 1 total mixed ration (TMR). Rye grass hay samples consisted of long hay and chopped hay particles retained on the 19- (19_PSPS hay), 8- (8_PSPS hay), and 1.18-mm (1.18_PSPS hay) Penn State Particle Separator (PSPS) screens and those collected on the pan (PSPS_pan hay). A sixth hay treatment was rye grass forage cut at 50-mm lengths and dried to hay (50-mm hay). Treatments were offered to 4 nonlactating and 4 lactating cows following rumen evacuation. Swallowed boli were collected and the number of chews per gram of ingested feed dry matter was determined. Feed and bolus particles of lengths ≥5mm were collected on a 1.6-mm screen using a horizontal wet sieving technique. This cut point was chosen, as the literature suggests that most fecal particles are shorter than 5mm. Dry matter proportions on this screen (PROP_1.6) were determined and particle lengths of retained particles were measured by image analysis. Mean particle lengths (ML) were calculated considering particles ≥5mm in length. Boli of long hay, of 19_PSPS hay, of 8_PSPS hay, and of 50-mm hay had similar ML of 10 to 11mm. Bolus PROP_1.6 were also similar between these treatments, ranging from 0.54 to 0.69. Bolus particle lengths and distributions of these treatments were not related to respective hay particles. Bolus of 1.18_PSPS hay had PROP_1.6 of 0.51 and a smaller ML of 8mm. The PSPS_pan hay had PROP_1.6 of only 0.33, but was still chewed intensely. Apparently, little particle size reduction occurred when cows ate the TMR or the silages. Feed and respective bolus PROP_1.6 were as follows: 0.66 and 0.59 in grass silage, 0.52 and 0.55 in corn silage, and 0.44 and 0.38 in the TMR

An incompressible two-dimensional multiphase particle-in-cell model for dense particle flows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snider, D.M.; O`Rourke, P.J.; Andrews, M.J.

1997-06-01

A two-dimensional, incompressible, multiphase particle-in-cell (MP-PIC) method is presented for dense particle flows. The numerical technique solves the governing equations of the fluid phase using a continuum model and those of the particle phase using a Lagrangian model. Difficulties associated with calculating interparticle interactions for dense particle flows with volume fractions above 5% have been eliminated by mapping particle properties to a Eulerian grid and then mapping back computed stress tensors to particle positions. This approach utilizes the best of Eulerian/Eulerian continuum models and Eulerian/Lagrangian discrete models. The solution scheme allows for distributions of types, sizes, and density of particles,more » with no numerical diffusion from the Lagrangian particle calculations. The computational method is implicit with respect to pressure, velocity, and volume fraction in the continuum solution thus avoiding courant limits on computational time advancement. MP-PIC simulations are compared with one-dimensional problems that have analytical solutions and with two-dimensional problems for which there are experimental data.« less

Visualization of Air Particle Dynamics in an Engine Inertial Particle Separator

NASA Astrophysics Data System (ADS)

Wolf, Jason; Zhang, Wei

2015-11-01

Unmanned Aerial Vehicles (UAVs) are regularly deployed around the world in support of military, civilian and humanitarian efforts. Due to their unique mission profiles, these advanced UAVs utilize various internal combustion engines, which consume large quantities of air. Operating these UAVs in areas with high concentrations of sand and dust can be hazardous to the engines, especially during takeoff and landing. In such events, engine intake filters quickly become saturated and clogged with dust particles, causing a substantial decrease in the UAVs' engine performance and service life. Development of an Engine Air Particle Separator (EAPS) with high particle separation efficiency is necessary for maintaining satisfactory performance of the UAVs. Inertial Particle Separators (IPS) have been one common effective method but they experience complex internal particle-laden flows that are challenging to understand and model. This research employs an IPS test rig to simulate dust particle separation under different flow conditions. Soda lime glass spheres with a mean diameter of 35-45 microns are used in experiments as a surrogate for airborne particulates encountered during flight. We will present measurements of turbulent flow and particle dynamics using flow visualization techniques to understand the multiphase fluid dynamics in the IPS device. This knowledge can contribute to design better performing IPS systems for UAVs. Cleveland State University, Cleveland, Ohio, 44115.

Precision gap particle separator

DOEpatents

Benett, William J.; Miles, Robin; Jones, II., Leslie M.; Stockton, Cheryl

2004-06-08

A system for separating particles entrained in a fluid includes a base with a first channel and a second channel. A precision gap connects the first channel and the second channel. The precision gap is of a size that allows small particles to pass from the first channel into the second channel and prevents large particles from the first channel into the second channel. A cover is positioned over the base unit, the first channel, the precision gap, and the second channel. An port directs the fluid containing the entrained particles into the first channel. An output port directs the large particles out of the first channel. A port connected to the second channel directs the small particles out of the second channel.

Three-dimensional particle-particle simulations: Dependence of relaxation time on plasma parameter

NASA Astrophysics Data System (ADS)

Zhao, Yinjian

2018-05-01

A particle-particle simulation model is applied to investigate the dependence of the relaxation time on the plasma parameter in a three-dimensional unmagnetized plasma. It is found that the relaxation time increases linearly as the plasma parameter increases within the range of the plasma parameter from 2 to 10; when the plasma parameter equals 2, the relaxation time is independent of the total number of particles, but when the plasma parameter equals 10, the relaxation time slightly increases as the total number of particles increases, which indicates the transition of a plasma from collisional to collisionless. In addition, ions with initial Maxwell-Boltzmann (MB) distribution are found to stay in the MB distribution during the whole simulation time, and the mass of ions does not significantly affect the relaxation time of electrons. This work also shows the feasibility of the particle-particle model when using GPU parallel computing techniques.

Apparatus for measuring particle properties

DOEpatents

Rader, Daniel J.; Castaneda, Jaime N.; Grasser, Thomas W.; Brockmann, John E.

1998-01-01

An apparatus for determining particle properties from detected light scattered by the particles. The apparatus uses a light beam with novel intensity characteristics to discriminate between particles that pass through the beam and those that pass through an edge of the beam. The apparatus can also discriminate between light scattered by one particle and light scattered by multiple particles. The particle's size can be determined from the intensity of the light scattered. The particle's velocity can be determined from the elapsed time between various intensities of the light scattered.

Optimizing parameter of particle damping based on Leidenfrost effect of particle flows

NASA Astrophysics Data System (ADS)

Lei, Xiaofei; Wu, Chengjun; Chen, Peng

2018-05-01

Particle damping (PD) has strongly nonlinearity. With sufficiently vigorous vibration conditions, it always plays excellent damping performance and the particles which are filled into cavity are on Leidenfrost state considered in particle flow theory. For investigating the interesting phenomenon, the damping effect of PD on this state is discussed by the developed numerical model which is established based on principle of gas and solid. Furtherly, the numerical model is reformed and applied to study the relationship of Leidenfrost velocity with characteristic parameters of PD such as particle density, diameter, mass packing ratio and diameter-length ratio. The results indicate that particle density and mass packing ratio can drastically improve the damping performance as opposed as particle diameter and diameter-length ratio, mass packing ratio and diameter-length ratio can low the excited intensity for Leidenfrost state. For discussing the application of the phenomenon in engineering, bound optimization by quadratic approximation (BOBYQA) method is employed to optimize mass packing ratio of PD for minimize maximum amplitude (MMA) and minimize total vibration level (MTVL). It is noted that the particle damping can drastically reduce the vibrating amplitude for MMA as Leidenfrost velocity equal to the vibrating velocity relative to maximum vibration amplitude. For MTVL, larger mass packing ratio is best option because particles at relatively wide frequency range is adjacent to Leidenfrost state.

Individual Aerosol Particles from Biomass Burning in Southern Africa Compositions and Aging of Inorganic Particles. 2; Compositions and Aging of Inorganic Particles

NASA Technical Reports Server (NTRS)

Li, Jia; Posfai, Mihaly; Hobbs, Peter V.; Buseck, Peter R.

2003-01-01

Individual aerosol particles collected over southern Africa during the SAFARI 2000 field study were studied using transmission electron microscopy and field-emission scanning electron microscopy. The sizes, shapes, compositions, mixing states, surface coatings, and relative abundances of aerosol particles from biomass burning, in boundary layer hazes, and in the free troposphere were compared, with emphasis on aging and reactions of inorganic smoke particles. Potassium salts and organic particles were the predominant species in the smoke, and most were internally mixed. More KCl particles occur in young smoke, whereas more K2SO4 and KNO3 particles were present in aged smoke. This change indicates that with the aging of the smoke, KCl particles from the fires were converted to K2SO4 and KNO3 through reactions with sulfur- and nitrogen- bearing species from biomass burning as well as other sources. More soot was present in smoke from flaming grass fires than bush and wood fires, probably due to the predominance of flaming combustion in grass fires. The high abundance of organic particles and soluble salts can affect the hygroscopic properties of biomass-burning aerosols and therefore influence their role as cloud condensation nuclei. Particles from biomass burning were important constituents of the regional hazes.

Review of Particle Physics

NASA Astrophysics Data System (ADS)

Beringer, J.; Arguin, J.-F.; Barnett, R. M.; Copic, K.; Dahl, O.; Groom, D. E.; Lin, C.-J.; Lys, J.; Murayama, H.; Wohl, C. G.; Yao, W.-M.; Zyla, P. A.; Amsler, C.; Antonelli, M.; Asner, D. M.; Baer, H.; Band, H. R.; Basaglia, T.; Bauer, C. W.; Beatty, J. J.; Belousov, V. I.; Bergren, E.; Bernardi, G.; Bertl, W.; Bethke, S.; Bichsel, H.; Biebel, O.; Blucher, E.; Blusk, S.; Brooijmans, G.; Buchmueller, O.; Cahn, R. N.; Carena, M.; Ceccucci, A.; Chakraborty, D.; Chen, M.-C.; Chivukula, R. S.; Cowan, G.; D'Ambrosio, G.; Damour, T.; de Florian, D.; de Gouvêa, A.; DeGrand, T.; de Jong, P.; Dissertori, G.; Dobrescu, B.; Doser, M.; Drees, M.; Edwards, D. A.; Eidelman, S.; Erler, J.; Ezhela, V. V.; Fetscher, W.; Fields, B. D.; Foster, B.; Gaisser, T. K.; Garren, L.; Gerber, H.-J.; Gerbier, G.; Gherghetta, T.; Golwala, S.; Goodman, M.; Grab, C.; Gritsan, A. V.; Grivaz, J.-F.; Grünewald, M.; Gurtu, A.; Gutsche, T.; Haber, H. E.; Hagiwara, K.; Hagmann, C.; Hanhart, C.; Hashimoto, S.; Hayes, K. G.; Heffner, M.; Heltsley, B.; Hernández-Rey, J. J.; Hikasa, K.; Höcker, A.; Holder, J.; Holtkamp, A.; Huston, J.; Jackson, J. D.; Johnson, K. F.; Junk, T.; Karlen, D.; Kirkby, D.; Klein, S. R.; Klempt, E.; Kowalewski, R. V.; Krauss, F.; Kreps, M.; Krusche, B.; Kuyanov, Yu. V.; Kwon, Y.; Lahav, O.; Laiho, J.; Langacker, P.; Liddle, A.; Ligeti, Z.; Liss, T. M.; Littenberg, L.; Lugovsky, K. S.; Lugovsky, S. B.; Mannel, T.; Manohar, A. V.; Marciano, W. J.; Martin, A. D.; Masoni, A.; Matthews, J.; Milstead, D.; Miquel, R.; Mönig, K.; Moortgat, F.; Nakamura, K.; Narain, M.; Nason, P.; Navas, S.; Neubert, M.; Nevski, P.; Nir, Y.; Olive, K. A.; Pape, L.; Parsons, J.; Patrignani, C.; Peacock, J. A.; Petcov, S. T.; Piepke, A.; Pomarol, A.; Punzi, G.; Quadt, A.; Raby, S.; Raffelt, G.; Ratcliff, B. N.; Richardson, P.; Roesler, S.; Rolli, S.; Romaniouk, A.; Rosenberg, L. J.; Rosner, J. L.; Sachrajda, C. T.; Sakai, Y.; Salam, G. P.; Sarkar, S.; Sauli, F.; Schneider, O.; Scholberg, K.; Scott, D.; Seligman, W. G.; Shaevitz, M. H.; Sharpe, S. R.; Silari, M.; Sjöstrand, T.; Skands, P.; Smith, J. G.; Smoot, G. F.; Spanier, S.; Spieler, H.; Stahl, A.; Stanev, T.; Stone, S. L.; Sumiyoshi, T.; Syphers, M. J.; Takahashi, F.; Tanabashi, M.; Terning, J.; Titov, M.; Tkachenko, N. P.; Törnqvist, N. A.; Tovey, D.; Valencia, G.; van Bibber, K.; Venanzoni, G.; Vincter, M. G.; Vogel, P.; Vogt, A.; Walkowiak, W.; Walter, C. W.; Ward, D. R.; Watari, T.; Weiglein, G.; Weinberg, E. J.; Wiencke, L. R.; Wolfenstein, L.; Womersley, J.; Woody, C. L.; Workman, R. L.; Yamamoto, A.; Zeller, G. P.; Zenin, O. V.; Zhang, J.; Zhu, R.-Y.; Harper, G.; Lugovsky, V. S.; Schaffner, P.

2012-07-01

This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2658 new measurements from 644 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 112 reviews are many that are new or heavily revised including those on Heavy-Quark and Soft-Collinear Effective Theory, Neutrino Cross Section Measurements, Monte Carlo Event Generators, Lattice QCD, Heavy Quarkonium Spectroscopy, Top Quark, Dark Matter, Vcb & Vub, Quantum Chromodynamics, High-Energy Collider Parameters, Astrophysical Constants, Cosmological Parameters, and Dark Matter.A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov/.The 2012 edition of Review of Particle Physics is published for the Particle Data Group as article 010001 in volume 86 of Physical Review D.This edition should be cited as: J. Beringer et al. (Particle Data Group), Phys. Rev. D 86, 010001 (2012).

Particle-free microchip processing

DOEpatents

Geller, Anthony S.; Rader, Daniel J.

1996-01-01

Method and apparatus for reducing particulate contamination in microchip processing are disclosed. The method and apparatus comprise means to reduce particle velocity toward the wafer before the particles can be deposited on the wafer surface. A reactor using electric fields to reduce particle velocity and prevent particulate contamination is disclosed. A reactor using a porous showerhead to reduce particle velocities and prevent particulate contamination is disclosed.

Suspension chemistry and electrophoretic deposition of zirconia electrolyte on conducting and non-conducting substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, Debasish; Basu, Rajendra N., E-mail: rnbasu@cgcri.res.in

2013-09-01

Graphical abstract: - Highlights: • Stable suspension of yttria stabilized zirconia (YSZ) obtained in isopropanol medium. • Suspension chemistry and process parameters for electrophoretic deposition optimized. • Deposited film quality changed with iodine and water (dispersants) concentration. • Dense YSZ film (∼5 μm) fabricated onto non-conducting porous NiO-YSZ anode substrate. - Abstract: Suspensions of 8 mol% yttria stabilized zirconia (YSZ) particulates in isopropanol medium are prepared using acetylacetone, iodine and water as dispersants. The effect of dispersants concentration on suspension stability, particle size distribution, electrical conductivity and pH of the suspensions are studied in detail to optimize the suspension chemistry.more » Electrophoretic deposition (EPD) has been conducted to produce thin and dense YSZ electrolyte films. Deposition kinetics have been studied in depth and good quality films on conducting substrate are obtained at an applied voltage of 15 V for 3 min. YSZ films are also fabricated on non-conducting NiO-YSZ anode substrate using a steel plate on the reverse side of the substrate. Upon co-firing at 1400 °C for 6 h a dense YSZ film of thickness ∼5 μm is obtained. Such a half cell (anode + electrolyte) can be used to fabricate a solid oxide fuel cell on applying a suitable cathode layer.« less

[Ultrafine particle number concentration and size distribution of vehicle exhaust ultrafine particles].

PubMed

Lu, Ye-qiang; Chen, Qiu-fang; Sun, Zai; Cai, Zhi-liang; Yang, Wen-jun

2014-09-01

Ultrafine particle (UFP) number concentrations obtained from three different vehicles were measured using fast mobility particle sizer (FMPS) and automobile exhaust gas analyzer. UFP number concentration and size distribution were studied at different idle driving speeds. The results showed that at a low idle speed of 800 rmin-1 , the emission particle number concentration was the lowest and showed a increasing trend with the increase of idle speed. The majority of exhaust particles were in Nuclear mode and Aitken mode. The peak sizes were dominated by 10 nm and 50 nm. Particle number concentration showed a significantly sharp increase during the vehicle acceleration process, and was then kept stable when the speed was stable. In the range of 0. 4 m axial distance from the end of the exhaust pipe, the particle number concentration decayed rapidly after dilution, but it was not obvious in the range of 0. 4-1 m. The number concentration was larger than the background concentration. Concentration of exhaust emissions such as CO, HC and NO showed a reducing trend with the increase of idle speed,which was in contrast to the emission trend of particle number concentration.

RESONATOR PARTICLE SEPARATOR

DOEpatents

Blewett, J.P.

1962-01-01

A wave guide resonator structure is described for use in separating particles of equal momentum but differing in mass and having energies exceeding one billion electron volts. The particles are those of sub-atomic size and are generally produced as a result of the bombardment of a target by a beam such as protons produced in a high-energy accelerator. In this wave guide construction, the particles undergo preferential deflection as a result of the presence of an electric field. The boundary conditions established in the resonator are such as to eliminate an interfering magnetic component, and to otherwise phase the electric field to obtain a traveling wave such as one which moves at the same speed as the unwanted particle. The latter undergoes continuous deflection over the whole length of the device and is, therefore, eliminated while the wanted particle is deflected in opposite directions over the length of the resonator and is thus able to enter an exit aperture. (AEC)

Lipid nanoparticles for the delivery of poorly water-soluble drugs.

PubMed

Bunjes, Heike

2010-11-01

This review discusses important aspects of lipid nanoparticles such as colloidal lipid emulsions and, in particular, solid lipid nanoparticles as carrier systems for poorly water-soluble drugs, with a main focus on the parenteral and peroral use of these carriers. A short historical background of the development of colloidal lipid emulsions and solid lipid nanoparticles is provided and their similarities and differences are highlighted. With regard to drug incorporation, parameters such as the chemical nature of the particle matrix and the physicochemical nature of the drug, effects of drug partition and the role of the particle interface are discussed. Since, because of the crystalline nature of their lipid core, solid lipid nanoparticles display some additional important features compared to emulsions, their specificities are introduced in more detail. This mainly includes their solid state behaviour (crystallinity, polymorphism and thermal behaviour) and the consequences of their usually non-spherical particle shape. Since lipid nanoemulsions and -suspensions are also considered as potential means to alter the pharmacokinetics of incorporated drug substances, some underlying basic considerations, in particular concerning the drug-release behaviour of such lipid nanodispersions on dilution, are addressed as well. Colloidal lipid emulsions and solid lipid nanoparticles are interesting options for the delivery of poorly water-soluble drug substances. Their specific physicochemical properties need, however, to be carefully considered to provide a rational basis for their development into effective carrier systems for a given delivery task. © 2010 The Author. Journal compilation © 2010 Royal Pharmaceutical Society of Great Britain.

Multilayer ceramic oxide solid electrolyte for fuel cells and electrolysis cells and method for fabrication thereof

NASA Technical Reports Server (NTRS)

Schroeder, James E. (Inventor); Anderson, Harlan U. (Inventor)

1990-01-01

An unitary layered ceramic structure is disclosed which comprises co-sintered layers. The co-sintered structure comprises a sintered central layer of yttria stabilized zirconia (YSZ) which is about 8 mole percent yttria and having a density of at least about 95% of theoretical, and sintered outer layers of strontium lanthanum manganite (LSM) having the approximate molecular composition La.sub.0.8 Sr.sub.0.2 MnO.sub.3, having a density from about 50 to about 60% of theoretical, and having interconnected porosity from about 40 to 50% with an interconnected pore diameter from about one micron to about five microns. The sintered central layer is sandwiched by and bonded and sintered to the outer layers and is essentially free of significant amounts of manganese. A process for making the unitary composition-of-matter is also disclosed which involves tape casting a LSM tape and then on top thereof casting a YSZ tape. The process comprises presintering LSM powder at 1250.degree. F., crushing the presintered commercially available LSM powder, forming a slurry with the crushed LSM, a binder and solvent, tape casting the slurry and allowing the slurry to air dry. A mixture of commercially available submicron size particle YSZ powder is milled with a dispersant and solvent to disperse the YSZ particles thereby forming a dispersed YSZ slurry. The YSZ slurry is then tape cast on the dried LSM tape. If desired, a third layer of LSM can be cast on top of the dried YSZ layer. After drying the composite LSM/YSZ and LSM/YSZ/LSM tapes are fired at 1300.degree. C. No migration of manganese into the YSZ layer was observed with scanning electron microscope/edax in the sintered multilayer tape.

Multilayer ceramic oxide solid electrolyte for fuel cells and electrolysis cells

NASA Technical Reports Server (NTRS)

Schroeder, James E. (Inventor); Anderson, Harlan U. (Inventor)

1991-01-01

A unitary layered ceramic structure is disclosed which comprises co-sintered layers. The co-sintered structure comprises a sintered central layer of yttria stabilized zirconia (YSZ) which is about 8 mole percent yttria and having a density of at least about 95% of theoretical, and sintered outer layers of strontium lanthanum manganite (LSM) having the approximate molecular composition La.sub.0.8 Sr.sub.0.2 MnO.sub.3, having a density from about 50 to about 60% of theoretical, and having interconnected porosity from about 40 to 50% with an interconnected pore diameter from about one micron to about five microns. The sintered central layer is sandwiched by and bonded and sintered to the outer layers and is essentially free of significant amounts of manganese. A process for making the unitary composition-of-matter is also disclosed which involves tape casting a LSM tape and then on top thereof casting a YSZ tape. The process comprises presintering LSM powder at 1250.degree. F., crushing the presintered commercially available LSM powder, forming a slurry with the crushed LSM, a binder and solvent, tape casting the slurry and allowing the slurry to air dry. A mixture of commercially available submicron size particle YSZ powder is milled with a dispersant and solvent to disperse the YSZ particles thereby forming a dispersed YSZ slurry. The YSZ slurry is then tape cast on the dried LSM tape. If desired, a third layer of LSM can be cast on top of the dried YSZ layer. After drying the composite LSM/YSZ and LSM/YSZ/LSM tapes are fired at 1300.degree. C. No migration of manganese into the YSZ layer was observed with scanning electron microscope/edax in the sintered multilayer tape.

Particle acceleration in solar flares

NASA Technical Reports Server (NTRS)

Ramaty, R.; Forman, M. A.

1987-01-01

The most direct signatures of particle acceleration in flares are energetic particles detected in interplanetary space and in the Earth atmosphere, and gamma rays, neutrons, hard X-rays, and radio emissions produced by the energetic particles in the solar atmosphere. The stochastic and shock acceleration theories in flares are reviewed and the implications of observations on particle energy spectra, particle confinement and escape, multiple acceleration phases, particle anistropies, and solar atmospheric abundances are discussed.

Digital micromirror device as programmable rough particle in interferometric particle imaging.

PubMed

Fromager, M; Aït Ameur, K; Brunel, M

2017-04-20

The 2D autocorrelation of the projection of an irregular rough particle can be estimated using the analysis of its interferometric out-of-focus image. We report the development of an experimental setup that creates speckle-like patterns generated by "programmable" rough particles of desired-shape. It should become an important tool for the development of new setups, configurations, and algorithms in interferometric particle imaging.

Particle-free microchip processing

DOEpatents

Geller, A.S.; Rader, D.J.

1996-06-04

Method and apparatus for reducing particulate contamination in microchip processing are disclosed. The method and apparatus comprise means to reduce particle velocity toward the wafer before the particles can be deposited on the wafer surface. A reactor using electric fields to reduce particle velocity and prevent particulate contamination is disclosed. A reactor using a porous showerhead to reduce particle velocities and prevent particulate contamination is disclosed. 5 figs.

Modelling and simulation of particle-particle interaction in a magnetophoretic bio-separation chip

NASA Astrophysics Data System (ADS)

Alam, Manjurul; Golozar, Matin; Darabi, Jeff

2018-04-01

A Lagrangian particle trajectory model is developed to predict the interaction between cell-bead particle complexes and to track their trajectories in a magnetophoretic bio-separation chip. Magnetic flux gradients are simulated in the OpenFOAM CFD software and imported into MATLAB to obtain the trapping lengths and trajectories of the particles. A connector vector is introduced to calculate the interaction force between cell-bead complexes as they flow through a microfluidic device. The interaction force calculations are performed for cases where the connector vector is parallel, perpendicular, and at an angle of 45° with the applied magnetic field. The trajectories of the particles are simulated by solving a system of eight ordinary differential equations using a fourth order Runge-Kutta method. The model is then used to study the effects of geometric positions and angles of the connector vector between the particles as well as the cell size, number of beads per cell, and flow rate on the interaction force and trajectories of the particles. The results show that the interaction forces may be attractive or repulsive, depending on the orientation of the connector vector distance between the particle complexes and the applied magnetic field. When the interaction force is attractive, the particles are observed to merge and trap sooner than a single particle, whereas a repulsive interaction force has little or no effect on the trapping length.

Particle blender

DOEpatents

Willey, Melvin G.

1981-01-01

An infinite blender that achieves a homogeneous mixture of fuel microspheres is provided. Blending is accomplished by directing respective groups of desired particles onto the apex of a stationary coaxial cone. The particles progress downward over the cone surface and deposit in a space at the base of the cone that is described by a flexible band provided with a wide portion traversing and in continuous contact with the circumference of the cone base and extending upwardly therefrom. The band, being attached to the cone at a narrow inner end thereof, causes the cone to rotate on its arbor when the band is subsequently pulled onto a take-up spool. As a point at the end of the wide portion of the band passes the point where it is tangent to the cone, the blended particles are released into a delivery tube leading directly into a mold, and a plate mounted on the lower portion of the cone and positioned between the end of the wide portion of the band and the cone assures release of the particles only at the tangent point.

Decomposition of Atmospheric Aerosol Phase Function by Particle Size and Morphology via Single Particle Scattering Measurements

NASA Astrophysics Data System (ADS)

Aptowicz, K. B.; Pan, Y.; Martin, S.; Fernandez, E.; Chang, R.; Pinnick, R. G.

2013-12-01

We report upon an experimental approach that provides insight into how particle size and shape affect the scattering phase function of atmospheric aerosol particles. Central to our approach is the design of an apparatus that measures the forward and backward scattering hemispheres (scattering patterns) of individual atmospheric aerosol particles in the coarse mode range. The size and shape of each particle is discerned from the corresponding scattering pattern. In particular, autocorrelation analysis is used to differentiate between spherical and non-spherical particles, the calculated asphericity factor is used to characterize the morphology of non-spherical particles, and the integrated irradiance is used for particle sizing. We found the fraction of spherical particles decays exponentially with particle size, decreasing from 11% for particles on the order of 1 micrometer to less than 1% for particles over 5 micrometer. The average phase functions of subpopulations of particles, grouped by size and morphology, are determined by averaging their corresponding scattering patterns. The phase functions of spherical and non-spherical atmospheric particles are shown to diverge with increasing size. In addition, the phase function of non-spherical particles is found to vary little as a function of the asphericity factor.

Epithelial stem cells are formed by small-particles released from particle-producing cells

PubMed Central

Kong, Wuyi; Zhu, Xiao Ping; Han, Xiu Juan; Nuo, Mu; Wang, Hong

2017-01-01

Recent spatiotemporal report demonstrated that epidermal stem cells have equal potential to divide or differentiate, with no asymmetric cell division observed. Therefore, how epithelial stem cells maintain lifelong stem-cell support still needs to be elucidated. In mouse blood and bone marrow, we found a group of large cells stained strongly for eosin and containing coiled-tubing-like structures. Many were tightly attached to each other to form large cellular clumps. After sectioning, these large cell-clumps were composed of not cells but numerous small particles, however with few small “naked” nuclei. The small particles were about 2 to 3 μm in diameter and stained dense red for eosin, so they may be rich in proteins. Besides the clumps composed of small particles, we identified clumps formed by fusion of the small particles and clumps of newly formed nucleated cells. These observations suggest that these small particles further fused and underwent cellularization. E-cadherin was expressed in particle-fusion areas, some “naked” nuclei and the newly formed nucleated cells, which suggests that these particles can form epithelial cells via fusion and nuclear remodeling. In addition, we observed similar-particle fusion before epithelial cellularization in mouse kidney ducts after kidney ischemia, which suggests that these particles can be released in the blood and carried to the target tissues for epithelial-cell regeneration. Oct4 and E-cadherin expressed in the cytoplasmic areas in cells that were rich in protein and mainly located in the center of the cellular clumps, suggesting that these newly formed cells have become tissue-specific epithelial stem cells. Our data provide evidence that these large particle-producing cells are the origin of epithelial stem cells. The epithelial stem cells are newly formed by particle fusion. PMID:28253358

Self Assembled Particles

NASA Technical Reports Server (NTRS)

Palacci, Jeremie (Inventor); Pine, David J. (Inventor); Chaikin, Paul Michael (Inventor); Sacanna, Stefano (Inventor)

2017-01-01

A self-assembling structure using non-equilibrium driving forces leading to 'living crystals' and other maniputable particles with a complex dynamics. The dynamic self-assembly assembly results from a competition between self-propulsion of particles and an attractive interaction between the particles. As a result of non-equilibrium driving forces, the crystals form, grow, collide, anneal, repair themselves and spontaneously self-destruct, thereby enabling reconfiguration and assembly to achieve a desired property.

Methods for forming particles

DOEpatents

Fox, Robert V.; Zhang, Fengyan; Rodriguez, Rene G.; Pak, Joshua J.; Sun, Chivin

2016-06-21

Single source precursors or pre-copolymers of single source precursors are subjected to microwave radiation to form particles of a I-III-VI.sub.2 material. Such particles may be formed in a wurtzite phase and may be converted to a chalcopyrite phase by, for example, exposure to heat. The particles in the wurtzite phase may have a substantially hexagonal shape that enables stacking into ordered layers. The particles in the wurtzite phase may be mixed with particles in the chalcopyrite phase (i.e., chalcopyrite nanoparticles) that may fill voids within the ordered layers of the particles in the wurtzite phase thus produce films with good coverage. In some embodiments, the methods are used to form layers of semiconductor materials comprising a I-III-VI.sub.2 material. Devices such as, for example, thin-film solar cells may be fabricated using such methods.

A novel approach to a fine particle coating using porous spherical silica as core particles.

PubMed

Ishida, Makoto; Uchiyama, Jumpei; Isaji, Keiko; Suzuki, Yuta; Ikematsu, Yasuyuki; Aoki, Shigeru

2014-08-01

Abstract The applicability of porous spherical silica (PSS) was evaluated as core particles for pharmaceutical products by comparing it with commercial core particles such as mannitol (NP-108), sucrose and microcrystalline cellulose spheres. We investigated the physical properties of core particles, such as particle size distribution, flow properties, crushing strength, plastic limit, drying rate, hygroscopic property and aggregation degree. It was found that PSS was a core particle of small particle size, low friability, high water adsorption capacity, rapid drying rate and lower occurrence of particle aggregation, although wettability is a factor to be carefully considered. The aggregation and taste-masking ability using PSS and NP-108 as core particles were evaluated at a fluidized-bed coating process. The functional coating under the excess spray rate shows different aggregation trends and dissolution profiles between PSS and NP-108; thereby, exhibiting the formation of uniform coating under the excess spray rate in the case of PSS. This expands the range of the acceptable spray feed rates to coat fine particles, and indicates the possibility of decreasing the coating time. The results obtained in this study suggested that the core particle, which has a property like that of PSS, was useful in overcoming such disadvantages as large particle size, which feels gritty in oral cavity; particle aggregation; and the long coating time of the particle coating process. These results will enable the practical fine particle coating method by increasing the range of optimum coating conditions and decreasing the coating time in fluidized bed technology.

Particle sizing of pharmaceutical aerosols via direct imaging of particle settling velocities.

PubMed

Fishler, Rami; Verhoeven, Frank; de Kruijf, Wilbur; Sznitman, Josué

2018-02-15

We present a novel method for characterizing in near real-time the aerodynamic particle size distributions from pharmaceutical inhalers. The proposed method is based on direct imaging of airborne particles followed by a particle-by-particle measurement of settling velocities using image analysis and particle tracking algorithms. Due to the simplicity of the principle of operation, this method has the potential of circumventing potential biases of current real-time particle analyzers (e.g. Time of Flight analysis), while offering a cost effective solution. The simple device can also be constructed in laboratory settings from off-the-shelf materials for research purposes. To demonstrate the feasibility and robustness of the measurement technique, we have conducted benchmark experiments whereby aerodynamic particle size distributions are obtained from several commercially-available dry powder inhalers (DPIs). Our measurements yield size distributions (i.e. MMAD and GSD) that are closely in line with those obtained from Time of Flight analysis and cascade impactors suggesting that our imaging-based method may embody an attractive methodology for rapid inhaler testing and characterization. In a final step, we discuss some of the ongoing limitations of the current prototype and conceivable routes for improving the technique. Copyright © 2017 Elsevier B.V. All rights reserved.

Motion of dust particles in nonuniform magnetic field and applicability of smoothed particle hydrodynamics simulation

NASA Astrophysics Data System (ADS)

Saitou, Y.

2018-01-01

An SPH (Smoothed Particle Hydrodynamics) simulation code is developed to reproduce our findings on behavior of dust particles, which were obtained in our previous experiments (Phys. Plasmas, 23, 013709 (2016) and Abst. 18th Intern. Cong. Plasma Phys. (Kaohsiung, 2016)). Usually, in an SPH simulation, a smoothed particle is interpreted as a discretized fluid element. Here we regard the particles as dust particles because it is known that behavior of dust particles in complex plasmas can be described using fluid dynamics equations in many cases. Various rotation velocities that are difficult to achieve in the experiment are given to particles at boundaries in the newly developed simulation and motion of particles is investigated. Preliminary results obtained by the simulation are shown.

Chemical compositions of subway particles in Seoul, Korea determined by a quantitative single particle analysis.

PubMed

Kang, Sunni; Hwang, HeeJin; Park, YooMyung; Kim, HyeKyoung; Ro, Chul-Un

2008-12-15

A novel single particle analytical technique, low-Z particle electron probe X-ray microanalysis, was applied to characterize seasonal subway samples collected at a subway station in Seoul, Korea. For all 8 samples collected twice in each season, 4 major types of subway particles, based on their chemical compositions, are significantly encountered: Fe-containing; soil-derived; carbonaceous; and secondary nitrate and/or sulfate particles. Fe-containing particles are generated indoors from wear processes at rail-wheel-brake interfaces while the others may be introduced mostly from the outdoor urban atmosphere. Fe-containing particles are the most frequently encountered with relative abundances in the range of 61-79%. In this study, it is shown that Fe-containing subway particles almost always exist either as partially or fully oxidized forms in underground subway microenvironments. Their relative abundances of Fe-containing particles increase as particle sizes decrease. Relative abundances of Fe-containing particles are higher in morning samples than in afternoon samples because of heavier train traffic in the morning. In the summertime samples, Fe-containing particles are the most abundantly encountered, whereas soil-derived and nitrate/sulfate particles are the least encountered, indicating the air-exchange between indoor and outdoor environments is limited in the summer, owing to the air-conditioning in the subway system. In our work, it was observed that the relative abundances of the particles of outdoor origin vary somewhat among seasonal samples to a lesser degree, reflecting that indoor emission sources predominate.

Influence of neighboring particles on the drag of a particle suspended in laminar flows

NASA Astrophysics Data System (ADS)

Roig, Adam Vincent

Understanding particle-fluid flows is very important for the areas of sedimentation in river beds, fluidized bed reactors, and other fields of multiphase flow. The effect of one particle on another in a fluid flow is not very well understood nor does a correlation exist to describe the behavior of the drag coefficient between particles. The use of Proteus was validated by comparison to previous studies to the result obtained through simulations in Proteus, including analysis of the wake structure of a single sphere. Two particles were then analyzed for various Reynolds numbers less than 250 but greater than 5 and for the dimensionless gap of L/D ≥ 2, where L is the distance between the two particle centers and D is the diameter of the particles. Two arrangements were used for simulation, with the particles spaced horizontally or vertically within the fluid flow. Both orientations were evaluated for the effects of the dimensionless gap on the drag coefficient. The wake structure at higher Reynolds numbers were also evaluated for effects due to neighboring particles. A correlation was developed for the case of the horizontal particles at a dimensionless gap, L/D ≥ 2 for the range of Reynolds numbers described. The orientation effect is then studied at a fixed distance for offsets of thirty, forty-five and sixty degrees from the horizontal. Results are also presented to evaluate the effect of the diameter of a neighboring particle. The current results are restricted to the case described in the work. Future studies may build on the current work to extend the work to other effects of neighboring particles and multiple particle influence.

Fabrication of composite films containing zirconia and cationic polyelectrolytes.

PubMed

Pang, Xin; Zhitomirsky, Igor

2004-03-30

Composite films were prepared by electrophoretic deposition of poly(ethylenimine) or poly(allylamine hydrochloride) combined with cathodic precipitation of zirconia. Films of up to several micrometers thick were obtained on Ni, Pt, stainless-steel, graphite, and carbon-felt substrates. When the concentration of polyelectrolytes in solutions and the deposition time were varied, the amount of the deposited material and its composition can be varied. The electrochemical intercalation of yttria-stabilized zirconia particles into the composite films has been demonstrated. Obtained results pave the way for the electrodeposition of other polymer-ceramic composites. The deposits were studied by thermogravimetric analysis, X-ray diffraction analysis, scanning electron microscopy, and atomic force microscopy. The mechanisms of deposition are discussed.

Magnetic characteristics of ultrafine Fe particles reduced from uniform iron oxide particles

NASA Astrophysics Data System (ADS)

Bridger, K.; Watts, J.; Tadros, M.; Xiao, Gang; Liou, S. H.; Chien, C. L.

1987-04-01

Uniform, cubic 0.05-μm iron oxide particles were formed by forced hydrolysis of ferric perchlorate. These particles were reduced to α-Fe by heating in hydrogen at temperatures between 300 and 500 °C. The effect of reduction temperature and various prereduction treatments on the microstructure of the iron particles will be discussed. Complete reduction to α-Fe was established by 57Fe Mössbauer spectroscopy and x-ray diffraction. Magnetic measurements on epoxy and polyurethane films containing these particles with various mass fractions gave coercivities as high as 1000 Oe. The relationship between the magnetic measurements and the microstructure will be discussed. Na2SiO3 is found to be the best coating material for the process of reducing iron oxide particles to iron.

Mixed-phase aerosol particles

NASA Astrophysics Data System (ADS)

Corti, T.; Krieger, U. K.; Koop, T.; Peter, T.

2003-04-01

Within a liquid aerosol particle a solid phase may coexist with the liquid over a wide range of ambient conditions. The optical properties of such particles are of interest for a number of reasons. They will affect the scattering albedo of atmospheric aerosols, may cause depolarisation in lidar measurements, and potentially open a window for studying the internal morphology and physical properties (e.g. wetting properties, diffusion constants) of composite particles in laboratory experiments. In this contribution, we will present results of experimental and theoretical work on mixed-phase aerosol particles. The optical properties of mixed-phase particles depend on the location of the inclusion in the liquid phase, which is determined by the surface tensions of the involved interfaces. In the case of complete wetting, the energetically favoured position of the inclusion is in the volume of the liquid phase. For partial wetting, a position at the surface of the liquid phase is favoured, with the contact angle between the solid, liquid and air being described by Young's equation. For systems with small contact angles, the difference in energy between an inclusion situated at the droplets surface and in its volume may be so small that the thermal energy kT is sufficient to displace the inclusion from the droplet surface into its volume. The critical contact angle depends on the size of the inclusion and the droplet and ranges from 0.1 to 10 degrees. Examples of mixed-phase aerosol particles are aged soot particles and sea salt particles at low relative humidity. For aged soot, contact angles on sulphuric acid clearly above 10 degrees have been reported, so that soot inclusions are expected to be located at the surface of aerosol particles. For mixed-phase sea salt particles, consisting of a solid NaCl inclusion and an aqueous solution of mainly NaCl and MgCl2, our measurements on macroscopic NaCl crystals show a contact angle clearly below 10 degrees and possibly as

Three Dimensional Characterization of Typical Urban and Desert Particles: Implications to Particle Optics

NASA Astrophysics Data System (ADS)

Goel, V.; Mishra, S.; Ahlawat, A. S.; Sharma, C.; Kotnala, R. K.

2017-12-01

Aerosol particles are generally considered as chemically homogeneous spheres in the retrieval techniques of ground and space borne observations which is not accurate approach and can lead to erroneous observations. For better simulation of optical and radiative properties of aerosols, a good knowledge of aerosol's morphology, chemical composition and internal structure is essential. Till date, many studies have reported the morphology and chemical composition of particles but very few of them provide internal structure and spatial distribution of different chemical species within the particle. The research on the effect of particle internal structure and its contribution to particle optics is extremely limited. In present work, we characterize the PM10 particles collected form typical arid (the Thar Desert, Rajasthan, India) and typical urban (New Delhi, India) environment using microscopic techniques. The particles were milled several times to investigate their internal structure. The EDS (Energy Dispersive X-ray Spectroscopy) spectra were recorded after each milling to check the variation in the chemical composition. In arid environment, Fe, Ca, C, Al, and Mg rich shell was observed over a Si rich particle whereas in urban environment, shell of Hg, Ag, C and N was observed over a Cu rich particle. Based on the observations, different model shapes [homogenous sphere and spheroid; heterogeneous sphere and spheroid; core shell] have been considered for assessing the associated uncertainties with the routine modeling of optical properties where volume equivalent homogeneous sphere approximation is considered. The details will be discussed during presentation.

Chemical vapor deposition of yttria-stabilized zirconia as a thermal barrier coating for gas turbine engines

NASA Astrophysics Data System (ADS)

Varanasi, Venu Gopal

The gas turbine engine uses an yttria-stabilized zirconia (YSZ) coating to provide thermal insulation for its turbine blades. This YSZ coating must be tetragonal in crystal structure, columnar in microstructure, and be 100--250 mum thick to provide for adequate protection for the turbine blades in the severe engine environment. Currently, YSZ coatings are fabricated by electron-beam physical vapor deposition (EB-PVD), but this fabrication method is cost intensive. Chemical vapor deposition (CVD) is a more commercially viable processing method and a possible alternative to EB-PVD. The deposition of tetragonal YSZ from gaseous metal and oxidation sources were studied. A chemical equilibrium analysis modeled the feasibility of depositing tetragonal YSZ for both chloride CVD (Zr-Y-C-O-Cl-H-Inert system) and metal-organic CVD (MOCVD) (Zr-Y-C-O-H system). Pure thermochemical properties and the assessed YSZ phase diagram were used in this analysis. Using the molar input of metals ((nY + nZr) and ( nY/(nY + nZr ) = 0.08)) as bases, equilibrium calculations showed that tetragonal YSZ formation was feasible. Tetragonal YSZ formation was feasible with high oxygen content (nO/(nY + nZr) > 8) and high temperature (T > 100°C) in the case of chloride CVD (Zr-Y-C-O-Cl-H-Inert). Tetragonal YSZ formation was feasible with high oxygen content (nO/( nY + nZr) > 5) and high temperature (T > 950°C) in the case of MOCVD (Zr-Y-C-O-H). Although solid carbon formation did not appear in chloride CVD, additional oxygen (nO/( nY + nZr) > 32) and low hydrogen content relative to carbon (nH/nC < 2) were required to avoid solid carbon formation in MOCVD. Coatings were deposited using a set of base conditions derived from the chemical equilibrium analysis. In chloride CVD, YCl3 was not included because of its low vapor pressure, thus, ZrCl4 was oxidized with the H2-CO2 gas mixture. Monoclinic ZrO2 coatings were deposited at the thermochemically optimized conditions (n O/(nY + nZr) > 8, T > 1004�

Steering particles by breaking symmetries

NASA Astrophysics Data System (ADS)

Bet, Bram; Samin, Sela; Georgiev, Rumen; Burak Eral, Huseyin; van Roij, René

2018-06-01

We derive general equations of motions for highly-confined particles that perform quasi-two-dimensional motion in Hele-Shaw channels, which we solve analytically, aiming to derive design principles for self-steering particles. Based on symmetry properties of a particle, its equations of motion can be simplified, where we retrieve an earlier-known equation of motion for the orientation of dimer particles consisting of disks (Uspal et al 2013 Nat. Commun. 4), but now in full generality. Subsequently, these solutions are compared with particle trajectories that are obtained numerically. For mirror-symmetric particles, excellent agreement between the analytical and numerical solutions is found. For particles lacking mirror symmetry, the analytic solutions provide means to classify the motion based on particle geometry, while we find that taking the side-wall interactions into account is important to accurately describe the trajectories.

The measurement of ultrafine particles: A pilot study using a portable particle counting technique to measure generated particles during a micromachining process

NASA Astrophysics Data System (ADS)

Handy, Rodney G.; Jackson, Mark J.; Robinson, Grant M.; Lafreniere, Michael D.

2006-04-01

The accurate measurement of airborne particles in the nanometer range is a challenging task. Because several studies have linked exposures to airborne ultrafine particles to elevated human health risks, the need to assess the concentrations of particles in the workplace that are below 100 nm in diameter is imperative. Several different techniques for monitoring nanoparticles are now available, and others are currently being tested for their merit. Laboratory condensation particle counters (CPC), field-portable CPC, nanometer differential mobility analyzers, electron microscopy, and other novel and experimental approaches to measuring nanoparticles have been recently used in investigations. The first part of this article gives an overview of these techniques, and provides the advantages and disadvantages for each. The second part of this article introduces a portable technique, coupling two particle measurement devices that are capable of characterizing microscale and nanoscale particles in the field environment. Specifically, this pilot study involved the use of a direct-reading CPC and a laser particle counter to measure airborne concentrations of ultrafine particles during a laboratory machining process. The measurements were evaluated in real time, and subsequently, decisions regarding human exposure could be made in an efficient and effective manner. Along with the results from this study, further research efforts in related areas are discussed.

Particle measurement systems and methods

DOEpatents

Steele, Paul T [Livermore, CA

2011-10-04

A system according to one embodiment includes a light source for generating light fringes; a sampling mechanism for directing a particle through the light fringes; and at least one light detector for detecting light scattered by the particle as the particle passes through the light fringes. A method according to one embodiment includes generating light fringes using a light source; directing a particle through the light fringes; and detecting light scattered by the particle as the particle passes through the light fringes using at least one light detector.

Thermal degradation events as health hazards - Particle vs gas phase effects, mechanistic studies with particles

NASA Technical Reports Server (NTRS)

Oberdoerster, G.; Ferin, J.; Finkelstein, J.; Soderholm, S.

1992-01-01

Experiments on animal subjects are performed to demonstrate that significant lung injury can result from the inhalation of ultrafine TiO2 or Al2O3 particles. The methods include intratracheal instillation of particles, long-term inhalation of particles, and in vitro studies of alveolar macrophages (AMs) to study the production of fibroplast growth factors. The ultrafine TiO2 particles are shown to induce more acute inflammatory reactions than larger particles and lead to persistent chronic effects in the AM-mediated clearance function of particles. The ultrafine particles also induce cytokines more readily, and the data generally suggests that the occurrence of such particles in thermal degradation events makes the fumes highly toxic. The exposure to thermal degradation products is therefore a critical concern for manned space missions with potentially degradable plastic products.

PARTICLE GROWTH IN HIGH-SPEED PARTICLE BEAM INLETS. (R823980)

EPA Science Inventory

Physical and chemical characterization of airborne particles is essential for determining their role in air pollution. Characterization instruments typically employ the use of sonic nozzles that transmit a wide range of particle sizes to a low-pressure region. The carrier gas ...

Carbon particles

DOEpatents

Hunt, Arlon J.

1984-01-01

A method and apparatus whereby small carbon particles are made by pyrolysis of a mixture of acetylene carried in argon. The mixture is injected through a nozzle into a heated tube. A small amount of air is added to the mixture. In order to prevent carbon build-up at the nozzle, the nozzle tip is externally cooled. The tube is also elongated sufficiently to assure efficient pyrolysis at the desired flow rates. A key feature of the method is that the acetylene and argon, for example, are premixed in a dilute ratio, and such mixture is injected while cool to minimize the agglomeration of the particles, which produces carbon particles with desired optical properties for use as a solar radiant heat absorber.

Investigation of refractory black carbon-containing particle morphologies using the single-particle soot photometer (SP2)

DOE PAGES

Sedlacek, III, Arthur J.; Lewis, Ernie R.; Onasch, Timothy B.; ...

2015-07-24

An important source of uncertainty in radiative forcing by absorbing aerosol particles is the uncertainty in their morphologies (i.e., the location of the absorbing substance on/in the particles). To examine the effects of particle morphology on the response of an individual black carbon-containing particle in a Single-Particle Soot Photometer (SP2), a series of experiments was conducted to investigate black carbon-containing particles of known morphology using Regal black (RB), a proxy for collapsed soot, as the light-absorbing substance. Particles were formed by coagulation of RB with either a solid substance (sodium chloride or ammonium sulfate) or a liquid substance (dioctyl sebacate),more » and by condensation with dioctyl sebacate, the latter experiment forming particles in a core-shell configuration. Each particle type experienced fragmentation (observed as negative lagtimes), and each yielded similar lagtime responses in some instances, confounding attempts to differentiate particle morphology using current SP2 lagtime analysis. SP2 operating conditions, specifically laser power and sample flow rate, which in turn affect the particle heating and dissipation rates, play an important role in the behavior of particles in the SP2, including probability of fragmentation. This behavior also depended on the morphology of the particles and on the thermo-chemical properties of the non-RB substance. Although these influences cannot currently be unambiguously separated, the SP2 analysis may still provide useful information on particle mixing states and black carbon particle sources.« less

A multi-parametric particle-pairing algorithm for particle tracking in single and multiphase flows

NASA Astrophysics Data System (ADS)

Cardwell, Nicholas D.; Vlachos, Pavlos P.; Thole, Karen A.

2011-10-01

Multiphase flows (MPFs) offer a rich area of fundamental study with many practical applications. Examples of such flows range from the ingestion of foreign particulates in gas turbines to transport of particles within the human body. Experimental investigation of MPFs, however, is challenging, and requires techniques that simultaneously resolve both the carrier and discrete phases present in the flowfield. This paper presents a new multi-parametric particle-pairing algorithm for particle tracking velocimetry (MP3-PTV) in MPFs. MP3-PTV improves upon previous particle tracking algorithms by employing a novel variable pair-matching algorithm which utilizes displacement preconditioning in combination with estimated particle size and intensity to more effectively and accurately match particle pairs between successive images. To improve the method's efficiency, a new particle identification and segmentation routine was also developed. Validation of the new method was initially performed on two artificial data sets: a traditional single-phase flow published by the Visualization Society of Japan (VSJ) and an in-house generated MPF data set having a bi-modal distribution of particles diameters. Metrics of the measurement yield, reliability and overall tracking efficiency were used for method comparison. On the VSJ data set, the newly presented segmentation routine delivered a twofold improvement in identifying particles when compared to other published methods. For the simulated MPF data set, measurement efficiency of the carrier phases improved from 9% to 41% for MP3-PTV as compared to a traditional hybrid PTV. When employed on experimental data of a gas-solid flow, the MP3-PTV effectively identified the two particle populations and reported a vector efficiency and velocity measurement error comparable to measurements for the single-phase flow images. Simultaneous measurement of the dispersed particle and the carrier flowfield velocities allowed for the calculation of

The influences of ambient particle composition and size on particle infiltration in Los Angeles, CA, residences.

PubMed

Sarnat, Stefanie Ebelt; Coull, Brent A; Ruiz, Pablo A; Koutrakis, Petros; Suh, Helen H

2006-02-01

Particle infiltration is a key determinant of the indoor concentrations of ambient particles. Few studies have examined the influence of particle composition on infiltration, particularly in areas with high concentrations of volatile particles, such as ammonium nitrate (NH4NO3). A comprehensive indoor monitoring study was conducted in 17 Los Angeles-area homes. As part of this study, indoor/outdoor concentration ratios during overnight (nonindoor source) periods were used to estimate the fraction of ambient particles remaining airborne indoors, or the particle infiltration factor (FINF), for fine particles (PM2.5), its nonvolatile (i.e., black carbon [BC]) and volatile (i.e., nitrate [NO3-]) components, and particle sizes ranging between 0.02 and 10 microm. FINF was highest for BC (median = 0.84) and lowest for NO3- (median = 0.18). The low FINF for NO3- was likely because of volatilization of NO3- particles once indoors, in addition to depositional losses upon building entry. The FINF for PM2.5 (median = 0.48) fell between those for BC and NO3-, reflecting the contributions of both particle components to PM25. FINF varied with particle size, air-exchange rate, and outdoor NO3- concentrations. The FINF for particles between 0.7 and 2 microm in size was considerably lower during periods of high as compared with low outdoor NO3- concentrations, suggesting that outdoor NO3- particles were of this size. This study demonstrates that infiltration of PM2.5 varies by particle component and is lowest for volatile species, such as NH4NO3. Our results suggest that volatile particle components may influence the ability for outdoor PM concentrations to represent indoor and, thus, personal exposures to particles of ambient origin, because volatilization of these particles causes the composition of PM2.5 to differ indoors and outdoors. Consequently, particle composition likely influences observed epidemiologic relationships based on outdoor PM concentrations, especially in areas

How subvisible particles become invisible-relevance of the refractive index for protein particle analysis.

PubMed

Zölls, Sarah; Gregoritza, Manuel; Tantipolphan, Ruedeeporn; Wiggenhorn, Michael; Winter, Gerhard; Friess, Wolfgang; Hawe, Andrea

2013-05-01

The aim of the present study was to quantitatively assess the relevance of transparency and refractive index (RI) on protein particle analysis by the light-based techniques light obscuration (LO) and Micro-Flow Imaging (MFI). A novel method for determining the RI of protein particles was developed and provided an RI of 1.41 for protein particles from two different proteins. An increased RI of the formulation by high protein concentration and/or sugars at pharmaceutically relevant levels was shown to lead to a significant underestimation of the subvisible particle concentration determined by LO and MFI. An RI match even caused particles to become "invisible" for the system, that is, not detectable anymore by LO and MFI. To determine the influence of formulation RI on particle measurements, we suggest the use of polytetrafluoroethylene (PTFE) particles to test a specific formulation for RI effects. In case of RI influences, we recommend also using a light-independent technique such as resonant mass measurement (RMM) (Archimedes) for subvisible particle analysis in protein formulations. Copyright © 2013 Wiley Periodicals, Inc.

Interaction of Burning Metal Particles

NASA Technical Reports Server (NTRS)

Dreizin, Edward L.; Berman, Charles H.; Hoffmann, Vern K.

1999-01-01

Physical characteristics of the combustion of metal particle groups have been addressed in this research. The combustion behavior and interaction effects of multiple metal particles has been studied using a microgravity environment, which presents a unique opportunity to create an "aerosol" consisting of relatively large particles, i.e., 50-300 micrometer diameter. Combustion behavior of such an aerosol could be examined using methods adopted from well-developed single particle combustion research. The experiment included fluidizing relatively large (order of 100 micrometer diameter) uniform metal particles under microgravity and igniting such an "aerosol" using a hot wire igniter. The flame propagation and details of individual particle combustion and particle interaction have been studied using a high speed movie and video-imaging with cameras coupled with microscope lenses to resolve individual particles. Interference filters were used to separate characteristic metal and metal oxide radiation bands form the thermal black body radiation. Recorded flame images were digitized and employed to understand the processes occurring in the burning aerosol. The development of individual particle flames, merging or separation, and extinguishing as well as induced particle motion have been analyzed to identify the mechanisms governing these processes. Size distribution, morphology, and elemental compositions of combustion products were characterized and used to link the observed in this project aerosol combustion phenomena with the recently expanded mechanism of single metal particle combustion.

The Particle Distribution in Liquid Metal with Ceramic Particles Mould Filling Process

NASA Astrophysics Data System (ADS)

Dong, Qi; Xing, Shu-ming

2017-09-01

Adding ceramic particles in the plate hammer is an effective method to increase the wear resistance of the hammer. The liquid phase method is based on the “with the flow of mixed liquid forging composite preparation of ZTA ceramic particle reinforced high chromium cast iron hammer. Preparation method for this system is using CFD simulation analysis the particles distribution of flow mixing and filling process. Taking the 30% volume fraction of ZTA ceramic composite of high chromium cast iron hammer as example, by changing the speed of liquid metal viscosity to control and make reasonable predictions of particles distribution before solidification.

Measuring momentum for charged particle tomography

DOEpatents

Morris, Christopher; Fraser, Andrew Mcleod; Schultz, Larry Joe; Borozdin, Konstantin N.; Klimenko, Alexei Vasilievich; Sossong, Michael James; Blanpied, Gary

2010-11-23

Methods, apparatus and systems for detecting charged particles and obtaining tomography of a volume by measuring charged particles including measuring the momentum of a charged particle passing through a charged particle detector. Sets of position sensitive detectors measure scattering of the charged particle. The position sensitive detectors having sufficient mass to cause the charged particle passing through the position sensitive detectors to scatter in the position sensitive detectors. A controller can be adapted and arranged to receive scattering measurements of the charged particle from the charged particle detector, determine at least one trajectory of the charged particle from the measured scattering; and determine at least one momentum measurement of the charged particle from the at least one trajectory. The charged particle can be a cosmic ray-produced charged particle, such as a cosmic ray-produced muon. The position sensitive detectors can be drift cells, such as gas-filled drift tubes.

Single-particle Analyses of Compositions, Morphology, and Viscosity of Aerosol Particles Collected During GoAmazon2014

NASA Astrophysics Data System (ADS)

Adachi, K.; Gong, Z.; Bateman, A. P.; Martin, S. T.; Cirino, G. G.; Artaxo, P.; Sedlacek, A. J., III; Buseck, P. R.

2014-12-01

Single-particle analysis using transmission electron microscopy (TEM) shows composition and morphology of individual aerosol particles collected during the GoAmazon2014 campaign. These TEM results indicate aerosol types and mixing states, both of which are important for evaluating particle optical properties and cloud condensation nuclei activity. The samples were collected at the T3 site, which is located in the Amazon forest with influences from the urban pollution plume from Manaus. Samples were also collected from the T0 site, which is in the middle of the jungle with minimal to no influences of anthropogenic sources. The aerosol particles mainly originated from 1) anthropogenic pollution (e.g., nanosphere soot, sulfate), 2) biogenic emissions (e.g., primary biogenic particles, organic aerosols), and 3) long-range transport (e.g., sea salts). We found that the biogenic organic aerosol particles contain homogeneously distributed potassium. Particle viscosity is important for evaluating gas-particle interactions and atmospheric chemistry for the particles. Viscosity can be estimated from the rebounding behavior at controlled relative humidities, i.e., highly viscous particles display less rebound on a plate than low-viscosity particles. We collected 1) aerosol particles from a plate (non-rebounded), 2) those that had rebounded from the plate and were then captured onto an adjacent sampling plate, and 3) particles from ambient air using a separate impactor sampler. Preliminary results show that more than 90% of non-rebounded particles consisted of nanosphere soot with or without coatings. The coatings mostly consisted of organic matter. Although rebounded particles also contain nanosphere soot (number fraction 64-69%), they were mostly internally mixed with sulfate, organic matter, or their mixtures. TEM tilted images suggested that the rebounded particles were less deformed on the substrate, whereas the non-rebounded particles were more deformed, which could

Sub-micron particle sampler apparatus and method for sampling sub-micron particles

DOEpatents

Gay, D.D.; McMillan, W.G.

1984-04-12

Apparatus and method steps for collecting sub-micron sized particles include a collection chamber and cryogenic cooling. The cooling is accomplished by coil tubing carrying nitrogen in liquid form, with the liquid nitrogen changing to the gas phase before exiting from the collection chamber in the tubing. Standard filters are used to filter out particles of diameter greater than or equal to 0.3 microns; however, the present invention is used to trap particles of less than 0.3 micron in diameter. A blower draws air to said collection chamber through a filter which filters particles with diameters greater than or equal to 0.3 micron. The air is then cryogenically cooled so that moisture and sub-micron sized particles in the air condense into ice on the coil. The coil is then heated so that the ice melts, and the liquid is then drawn off and passed through a Buchner funnel where the liquid is passed through a Nuclepore membrane. A vacuum draws the liquid through the Nuclepore membrane, with the Nuclepore membrane trapping sub-micron sized particles therein. The Nuclepore membrane is then covered on its top and bottom surfaces with sheets of Mylar and the assembly is then crushed into a pellet. This effectively traps the sub-micron sized particles for later analysis. 6 figures.

Consolidation of Partially Stabilized ZrO2 in the Presence of a Noncontacting Electric Field

NASA Astrophysics Data System (ADS)

Majidi, Hasti; van Benthem, Klaus

2015-05-01

Electric field-assisted sintering techniques demonstrate accelerated densification at lower temperatures than the conventional sintering methods. However, it is still debated whether the applied field and/or resulting currents are responsible for the densification enhancement. To distinguish the effects of an applied field from current flow, in situ scanning transmission electron microscopy experiments with soft agglomerates of partially stabilized yttria-doped zirconia particles are carried out. A new microelectromechanical system-based sample support is used to heat particle agglomerates while simultaneously exposing them to an externally applied noncontacting electric field. Under isothermal condition at 900 °C , an electric field strength of 500 V /cm shows a sudden threefold enhancement in the shrinkage of the agglomerates. The applied electrostatic potential lowers the activation energy for point defect formation within the space charge zone and therefore promotes consolidation. Obtaining similar magnitudes of shrinkage in the absence of any electric field requires a higher temperature and longer time.

Effective Parameters in Axial Injection Suspension Plasma Spray Process of Alumina-Zirconia Ceramics

NASA Astrophysics Data System (ADS)

Tarasi, F.; Medraj, M.; Dolatabadi, A.; Oberste-Berghaus, J.; Moreau, C.

2008-12-01

Suspension plasma spray (SPS) is a novel process for producing nano-structured coatings with metastable phases using significantly smaller particles as compared to conventional thermal spraying. Considering the complexity of the system there is an extensive need to better understand the relationship between plasma spray conditions and resulting coating microstructure and defects. In this study, an alumina/8 wt.% yttria-stabilized zirconia was deposited by axial injection SPS process. The effects of principal deposition parameters on the microstructural features are evaluated using the Taguchi design of experiment. The microstructural features include microcracks, porosities, and deposition rate. To better understand the role of the spray parameters, in-flight particle characteristics, i.e., temperature and velocity were also measured. The role of the porosity in this multicomponent structure is studied as well. The results indicate that thermal diffusivity of the coatings, an important property for potential thermal barrier applications, is barely affected by the changes in porosity content.

DEM Particle Fracture Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Boning; Herbold, Eric B.; Homel, Michael A.

2015-12-01

An adaptive particle fracture model in poly-ellipsoidal Discrete Element Method is developed. The poly-ellipsoidal particle will break into several sub-poly-ellipsoids by Hoek-Brown fracture criterion based on continuum stress and the maximum tensile stress in contacts. Also Weibull theory is introduced to consider the statistics and size effects on particle strength. Finally, high strain-rate split Hopkinson pressure bar experiment of silica sand is simulated using this newly developed model. Comparisons with experiments show that our particle fracture model can capture the mechanical behavior of this experiment very well, both in stress-strain response and particle size redistribution. The effects of density andmore » packings o the samples are also studied in numerical examples.« less

Thermal degradation events as health hazards: Particle vs gas phase effects, mechanistic studies with particles

NASA Astrophysics Data System (ADS)

Oberdörster, G.; Ferin, J.; Finkelstein, J.; Soderholm, S.

Exposure to thermal degradation products arising from fire or smoke could be a major concern for manned space missions. Severe acute lung damage has been reported in people after accidental exposure to fumes from plastic materials, and animal studies revealed the extremely high toxicity of freshly generated fumes whereas a decrease in toxicity of aged fumes has been found. This and the fact that toxicity of the freshly generated fumes can be prevented with filters raises the question whether the toxicity may be due to the particulate rather than the gas phase components of the thermodegradation products. Indeed, results from recent studies implicate ultrafine particles (particle diameter in the nm range) as potential severe pulmonary toxicants. We have conducted a number of in vivo (inhalation and instillation studies in rats) and in vitro studies to test the hypothesis that ultrafine particles possess an increased potential to injure the lung compared to larger-sized particles. We used as surrogate particles ultrafine TiO 2 particles (12 and 20 nm diameter). Results in exposed rats showed that the ultrafine TiO 2 particles not only induce a greater acute inflammatory reaction in the lung than larger-sized TiO 2 particles, but can also lead to persistent chronic effects, as indicated by an adverse effect on alveolar macrophage mediated clearance function of particles. Release of mediators from alveolar macrophages during phagocytosis of the ultrafine particles and an increased access of the ultrafine particles to the pulmonary interstitium are likely factors contributing to their pulmonary toxicity. In vitro studies with lung cells (alveolar macrophages) showed, in addition, that ultrafine TiO 2 particles have a greater potential to induce cytokines than larger-sized particles. We conclude from our present studies that ultrafine particles have a significant potential to injure the lung and that their occurrence in thermal degradation events can play a major role in

Filling carbon nanotubes with particles.

PubMed

Kim, Byong M; Qian, Shizhi; Bau, Haim H

2005-05-01

The filling of carbon nanotubes (CNTs) with fluorescent particles was studied experimentally and theoretically. The fluorescent signals emitted by the particles were visible through the walls of the nanotubes, and the particles inside the tubes were observable with an electron microscope. Taking advantage of the template-grown carbon nanotubes' transparency to fluorescent light, we measured the filling rate of the tubes with particles at room conditions. Liquids such as ethylene glycol, water, and ethylene glycol/water mixtures, laden with 50 nm diameter fluorescent particles, were brought into contact with 500 nm diameter CNTs. The liquid and the particles' transport were observed, respectively, with optical and fluorescence microscopy. The CNTs were filled controllably with particles by the complementary action of capillary forces and the evaporation of the liquid. The experimental results were compared and favorably agreed with theoretical predictions. This is the first report on fluorescence studies of particle transport in carbon nanotubes.

Interaction of Burning Metal Particles

NASA Technical Reports Server (NTRS)

Dreizin, Edward L.; Berman, Charles H.; Hoffmann, Vern K.

1999-01-01

Physical characteristics of the combustion of metal particle groups have been addressed in this research. The combustion behavior and interaction effects of multiple metal particles has been studied using a microgravity environment, which presents a unique opportunity to create an "aerosol" consisting of relatively large particles, i.e., 50-300 m diameter. Combustion behavior of such an aerosol could be examined using methods adopted from well-developed single particle combustion research. The experiment included fluidizing relatively large (order of 100 m diameter) uniform metal particles under microgravity and igniting such an "aerosol" using a hot wire igniter. The flame propagation and details of individual particle combustion and particle interaction have been studied using a high speed movie and video-imaging with cameras coupled with microscope lenses to resolve individual particles. Interference filters were used to separate characteristic metal and metal oxide radiation bands from the thermal black body radiation. Recorded flame images were digitized and various image processing techniques including flame position tracking, color separation, and pixel by pixel image comparison were employed to understand the processes occurring in the burning aerosol. The development of individual particle flames, merging or separation, and extinguishment as well as induced particle motion have been analyzed to identify the mechanisms governing these processes. Size distribution, morphology, and elemental compositions of combustion products were characterized and used to link the observed in this project aerosol combustion phenomena with the recently expanded mechanism of single metal particle combustion.

Pairwise-interaction extended point-particle model for particle-laden flows

NASA Astrophysics Data System (ADS)

Akiki, G.; Moore, W. C.; Balachandar, S.

2017-12-01

In this work we consider the pairwise interaction extended point-particle (PIEP) model for Euler-Lagrange simulations of particle-laden flows. By accounting for the precise location of neighbors the PIEP model goes beyond local particle volume fraction, and distinguishes the influence of upstream, downstream and laterally located neighbors. The two main ingredients of the PIEP model are (i) the undisturbed flow at any particle is evaluated as a superposition of the macroscale flow and a microscale flow that is approximated as a pairwise superposition of perturbation fields induced by each of the neighboring particles, and (ii) the forces and torque on the particle are then calculated from the undisturbed flow using the Faxén form of the force relation. The computational efficiency of the standard Euler-Lagrange approach is retained, since the microscale perturbation fields induced by a neighbor are pre-computed and stored as PIEP maps. Here we extend the PIEP force model of Akiki et al. [3] with a corresponding torque model to systematically include the effect of perturbation fields induced by the neighbors in evaluating the net torque. Also, we use DNS results from a uniform flow over two stationary spheres to further improve the PIEP force and torque models. We then test the PIEP model in three different sedimentation problems and compare the results against corresponding DNS to assess the accuracy of the PIEP model and improvement over the standard point-particle approach. In the case of two sedimenting spheres in a quiescent ambient the PIEP model is shown to capture the drafting-kissing-tumbling process. In cases of 5 and 80 sedimenting spheres a good agreement is obtained between the PIEP simulation and the DNS. For all three simulations, the DEM-PIEP was able to recreate, to a good extent, the results from the DNS, while requiring only a negligible fraction of the numerical resources required by the fully-resolved DNS.

Particle Sizer

NASA Technical Reports Server (NTRS)

1987-01-01

Microspheres are tiny plastic beads that represent the first commercial products manufactured in orbit. An example of how they are used is a new aerodynamic particle sizer designated APS 33B produced by TSI Incorporated. TSI purchased the microspheres from the National Bureau of Standards which certified their exact size and the company uses them in calibration of the APS 33B* instrument, latest in a line of TSI systems for generating counting and weighing minute particles of submicron size. Instruments are used for evaluating air pollution control devices, quantifying environments, meteorological research, testing filters, inhalation, toxicology and other areas where generation or analysis of small airborne particles is required. * The APS 33B is no longer being manufactured. An improved version, APS 3320, is now being manufactured. 2/28/97

Applicability of regular particle shapes in light scattering calculations for atmospheric ice particles.

PubMed

Macke, A; Mishchenko, M I

1996-07-20

We ascertain the usefulness of simple ice particle geometries for modeling the intensity distribution of light scattering by atmospheric ice particles. To this end, similarities and differences in light scattering by axis-equivalent, regular and distorted hexagonal cylindric, ellipsoidal, and circular cylindric ice particles are reported. All the results pertain to particles with sizes much larger than a wavelength and are based on a geometrical optics approximation. At a nonabsorbing wavelength of 0.55 µm, ellipsoids (circular cylinders) have a much (slightly) larger asymmetry parameter g than regular hexagonal cylinders. However, our computations show that only random distortion of the crystal shape leads to a closer agreement with g values as small as 0.7 as derived from some remote-sensing data analysis. This may suggest that scattering by regular particle shapes is not necessarily representative of real atmospheric ice crystals at nonabsorbing wavelengths. On the other hand, if real ice particles happen to be hexagonal, they may be approximated by circular cylinders at absorbing wavelengths.

Effect of diffusional creep on particle morphology of polycrystalline alloys strengthened by second phase particles

NASA Technical Reports Server (NTRS)

Wittenberger, J. D.; Behrendt, D. R.

1973-01-01

Diffusional creep in a polycrystalline alloy containing second-phase particles can disrupt the particle morphology. For alloys which depend on the particle distribution for strength, changes in the particle morphology can affect the mechanical properties. Recent observations of diffusional creep in alloys containing soluble particles (gamma-prime strengthened Ni base alloys) and inert particles have been reexamined in light of the basic mechanisms of diffusional creep, and a generalized model of this effect is proposed. The model indicates that diffusional creep will generally result in particle-free regions in the vicinity of grain boundaries serving as net vacancy sources. The factors which control the changes in second-phase morphology have been identified, and methods of reducing the effects of diffusional creep are suggested.

Effect of particle-size dynamics on properties of dense spongy-particle systems: Approach towards equilibrium.

PubMed

Zakhari, Monica E A; Anderson, Patrick D; Hütter, Markus

2017-07-01

Open-porous deformable particles, often envisaged as sponges, are ubiquitous in biological and industrial systems (e.g., casein micelles in dairy products and microgels in cosmetics). The rich behavior of these suspensions is owing to the elasticity of the supporting network of the particle, and the viscosity of permeating solvent. Therefore, the rate-dependent size change of these particles depends on their structure, i.e., the permeability. This work aims at investigating the effect of the particle-size dynamics and the underlying particle structure, i.e., the particle permeability, on the transient and long-time behavior of suspensions of spongy particles in the absence of applied deformation, using the dynamic two-scale model developed by Hütter et al. [Farad. Discuss. 158, 407 (2012)1359-664010.1039/c2fd20025b]. In the high-density limit, the transient behavior is found to be accelerated by the particle-size dynamics, even at average size changes as small as 1%. The accelerated dynamics is evidenced by (i) the higher short-time diffusion coefficient as compared to elastic-particle systems and (ii) the accelerated formation of the stable fcc crystal structure. Furthermore, after long times, the particle-size dynamics of spongy particles is shown to result in lower stationary values of the energy and normal stresses as compared to elastic-particle systems. This dependence of the long-time behavior of these systems on the permeability, that essentially is a transport coefficient and hence must not affect the equilibrium properties, confirms that full equilibration has not been reached.

Effect of particle-size dynamics on properties of dense spongy-particle systems: Approach towards equilibrium

NASA Astrophysics Data System (ADS)

Zakhari, Monica E. A.; Anderson, Patrick D.; Hütter, Markus

2017-07-01

Open-porous deformable particles, often envisaged as sponges, are ubiquitous in biological and industrial systems (e.g., casein micelles in dairy products and microgels in cosmetics). The rich behavior of these suspensions is owing to the elasticity of the supporting network of the particle, and the viscosity of permeating solvent. Therefore, the rate-dependent size change of these particles depends on their structure, i.e., the permeability. This work aims at investigating the effect of the particle-size dynamics and the underlying particle structure, i.e., the particle permeability, on the transient and long-time behavior of suspensions of spongy particles in the absence of applied deformation, using the dynamic two-scale model developed by Hütter et al. [Farad. Discuss. 158, 407 (2012), 10.1039/c2fd20025b]. In the high-density limit, the transient behavior is found to be accelerated by the particle-size dynamics, even at average size changes as small as 1 % . The accelerated dynamics is evidenced by (i) the higher short-time diffusion coefficient as compared to elastic-particle systems and (ii) the accelerated formation of the stable fcc crystal structure. Furthermore, after long times, the particle-size dynamics of spongy particles is shown to result in lower stationary values of the energy and normal stresses as compared to elastic-particle systems. This dependence of the long-time behavior of these systems on the permeability, that essentially is a transport coefficient and hence must not affect the equilibrium properties, confirms that full equilibration has not been reached.

Amorphous silicon ionizing particle detectors

DOEpatents

Street, Robert A.; Mendez, Victor P.; Kaplan, Selig N.

1988-01-01

Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation.

Particle-Charge Spectrometer

NASA Technical Reports Server (NTRS)

Fuerstenau, Stephen; Wilson, Gregory R.

2008-01-01

An instrument for rapidly measuring the electric charges and sizes (from approximately 1 to approximately 100 micrometers) of airborne particles is undergoing development. Conceived for monitoring atmospheric dust particles on Mars, instruments like this one could also be used on Earth to monitor natural and artificial aerosols in diverse indoor and outdoor settings for example, volcanic regions, clean rooms, powder-processing machinery, and spray-coating facilities. The instrument incorporates a commercially available, low-noise, ultrasensitive charge-sensing preamplifier circuit. The input terminal of this circuit--the gate of a field-effect transistor--is connected to a Faraday-cage cylindrical electrode. The charged particles of interest are suspended in air or other suitable gas that is made to flow along the axis of the cylindrical electrode without touching the electrode. The flow can be channeled and generated by any of several alternative means; in the prototype of this instrument, the gas is drawn along a glass capillary tube (see upper part of figure) coaxial with the electrode. The size of a particle affects its rate of acceleration in the flow and thus affects the timing and shape of the corresponding signal peak generated by the charge-sensing amplifier. The charge affects the magnitude (and thus also the shape) of the signal peak. Thus, the signal peak (see figure) conveys information on both the size and electric charge of a sensed particle. In experiments thus far, the instrument has been found to be capable of measuring individual aerosol particle charges of magnitude greater than 350 e (where e is the fundamental unit of electric charge) with a precision of +/- 150 e. The instrument can sample particles at a rate as high as several thousand per second.

In Situ Solid Particle Generator

NASA Technical Reports Server (NTRS)

Agui, Juan H.; Vijayakumar, R.

2013-01-01

Particle seeding is a key diagnostic component of filter testing and flow imaging techniques. Typical particle generators rely on pressurized air or gas sources to propel the particles into the flow field. Other techniques involve liquid droplet atomizers. These conventional techniques have drawbacks that include challenging access to the flow field, flow and pressure disturbances to the investigated flow, and they are prohibitive in high-temperature, non-standard, extreme, and closed-system flow conditions and environments. In this concept, the particles are supplied directly within a flow environment. A particle sample cartridge containing the particles is positioned somewhere inside the flow field. The particles are ejected into the flow by mechanical brush/wiper feeding and sieving that takes place within the cartridge chamber. Some aspects of this concept are based on established material handling techniques, but they have not been used previously in the current configuration, in combination with flow seeding concepts, and in the current operational mode. Unlike other particle generation methods, this concept has control over the particle size range ejected, breaks up agglomerates, and is gravity-independent. This makes this device useful for testing in microgravity environments.

Mechanical properties of hot isostatically pressed zirconia (2 mol% yttria)-reinforced molybdenum disilicide composite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamada, Toshihiro; Hirota, Ken; Yamaguchi, Osamu

1995-07-01

Dense sintered composites of ZrO{sub 2} (2 mol% Y{sub 2}O{sub 3}) and MoSi{sub 2} have been fabricated by hot isostatic pressing for 2 h at 1400 C under 196 MPa. The ZrO{sub 2} particles in the composites consist of only t-ZrO{sub 2}. There is no reaction between ZrO{sub 2} and MoSi{sub 2}. Microstructures and mechanical properties are examined, in connection with increased ZrO{sub 2} content. The fracture toughness and bending strength of the composite with 40 mol% ZrO{sub 2} addition are 6.18 MPa{center_dot}m{sup 1/2} and 1034 MPa, respectively.

Sound absorption by suspensions of nonspherical particles: Measurements compared with predictions using various particle sizing techniques

NASA Astrophysics Data System (ADS)

Richards, Simon D.; Leighton, Timothy G.; Brown, Niven R.

2003-10-01

Knowledge of the particle size distribution is required in order to predict ultrasonic absorption in polydisperse particulate suspensions. This paper shows that the method used to measure the particle size distribution can lead to important differences in the predicted absorption. A reverberation technique developed for measuring ultrasonic absorption by suspended particles is used to measure the absorption in suspensions of nonspherical particles. Two types of particulates are studied: (i) kaolin (china clay) particles which are platelike in form; and (ii) calcium carbonate particles which are more granular. Results are compared to theoretical predictions of visco-inertial absorption by suspensions of spherical particles. The particle size distributions, which are required for these predictions, are measured by laser diffraction, gravitational sedimentation and centrifugal sedimentation, all of which assume spherical particles. For a given sample, each sizing technique yields a different size distribution, leading to differences in the predicted absorption. The particle size distributions obtained by gravitational and centrifugal sedimentation are reinterpreted to yield a representative size distribution of oblate spheroids, and predictions for absorption by these spheroids are compared with the measurements. Good agreement between theory and measurement for the flat kaolin particles is obtained, demonstrating that these particles can be adequately represented by oblate spheroids.

Numerical investigation of the effect of particle concentration on particle measurement by digital holography

NASA Astrophysics Data System (ADS)

Zhao, Huafeng; Zhou, Binwu; Wu, Xuecheng; Wu, Yingchun; Gao, Xiang; Gréhan, Gérard; Cen, Kefa

2014-04-01

Digital holography plays a key role in particle field measurement, and appears to be a strong contender as the next-generation technology for diagnostics of 3D particle field. However, various recording parameters, such as the recording distance, the particle size, the wavelength, the size of the CCD chip, the pixel size and the particle concentration, will affect the results of the reconstruction, and may even determine the success or failure of a measurement. This paper presents a numerical investigation on the effect of particle concentration, the volume depth to evaluate the capability of digital holographic microscopy. Standard particles holograms with all known recording parameters are numerically generated by using a common procedure based on Lorenz-Mie scattering theory. Reconstruction of those holograms are then performed by a wavelet-transform based method. Results show that the reconstruction efficiency decreases quickly until particle concentration reaches 50×104 (mm-3), and decreases linearly with the increase of particle concentration from 50 × 104 (mm-3) to 860 × 104 (mm-3) in the same volume. The first half of the line waves larger than the second half. It also indicates that the increase of concentration leads the rise in average diameter error and z position error of particles. Besides, the volume depth also plays a key role in reconstruction.

Anatomy of Particle Diffusion

ERIC Educational Resources Information Center

Bringuier, E.

2009-01-01

The paper analyses particle diffusion from a thermodynamic standpoint. The main goal of the paper is to highlight the conceptual connection between particle diffusion, which belongs to non-equilibrium statistical physics, and mechanics, which deals with particle motion, at the level of third-year university courses. We start out from the fact…

Amorphous silicon ionizing particle detectors

DOEpatents

Street, R.A.; Mendez, V.P.; Kaplan, S.N.

1988-11-15

Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation. 15 figs.

Electrospray-assisted ultraviolet aerodynamic particle sizer spectrometer for real-time characterization of bacterial particles.

PubMed

Jung, Jae Hee; Lee, Jung Eun; Hwang, Gi Byoung; Lee, Byung Uk; Lee, Seung Bok; Jurng, Jong Soo; Bae, Gwi Nam

2010-01-15

The ultraviolet aerodynamic particle sizer (UVAPS) spectrometer is a novel, commercially available aerosol counter for real-time, continuous monitoring of viable bioaerosols based on the fluorescence induced from living microorganisms. For aerosolization of liquid-based microorganisms, general aerosolization methods such as atomization or nebulization may not be adequate for an accurate and quantitative characterization of the microorganisms because of the formation of agglomerated particles. In such cases, biological electrospray techniques have an advantage because they generate nonagglomerated particles, attributable to the repulsive electrical forces among particles with unipolar charges. Biological electrosprays are quickly gaining potential for the detection and control of living organisms in applications ranging from mass spectrometry to developmental microbiology. In this study, we investigated the size distribution, total concentration, and fluorescence percentage of bacterial particles in a real-time manner by electrospray-assisted UVAPS. A suspension containing Escherichia coli as a test microorganism was sprayed in a steady cone-jet mode using a specially designed electrospray system with a point-to-orifice-plate configuration based on charge-reduced electrospray size spectrometry. With the electrospray process, 98% of the total E. coli particle number concentration had a size of <1 mum and the geometric mean diameter was 0.779 mum, as compared with the respective values of 78% and 0.907 mum after nebulization. The fractions of fluorescence responsive particles and of particles that contained viable organisms in culture were 12% and 7%, respectively, from the electrospray process and 34% and 24% from nebulization. These results demonstrate that (1) the presence of agglomerated particles can lead to markedly overestimated fluorescence and culturability percentages compared with the values obtained from nonagglomerated particles, and (2) electrospray

Particle aggregation during receptor-mediated endocytosis

NASA Astrophysics Data System (ADS)

Mao, Sheng; Kosmrlj, Andrej

Receptor-mediated endocytosis of particles is driven by large binding energy between ligands on particles and receptors on a membrane, which compensates for the membrane bending energy and for the cost due to the mixing entropy of receptors. While the receptor-mediated endocytosis of individual particle is well understood, much less is known about the joint entry of multiple particles. Here, we demonstrate that the endocytosis of multiple particles leads to a kinetically driven entropic attraction, which may cause the aggregation of particles observed in experiments. During the endocytosis particles absorb nearby receptors and thus produce regions, which are depleted of receptors. When such depleted regions start overlapping, the corresponding particles experience osmotic-like attractive entropic force. If the attractive force between particles is large enough to overcome the repulsive interaction due to membrane bending, then particles tend to aggregate provided that they are sufficiently close, such that they are not completely engulfed before they come in contact. We discuss the necessary conditions for the aggregation of cylindrical particles during receptor-mediated endocytosis and comment on the generalization to spherical particles.

Review of particle physics

DOE PAGES

Olive, K. A.

2016-10-01

The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 3,062 new measurements from 721 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders,more » Probability and Statistics. As a result, among the 117 reviews are many that are new or heavily revised, including those on Pentaquarks and Inflation.« less

Energetic solar particle events

NASA Technical Reports Server (NTRS)

Fenton, K. B.; Fenton, A. G.; Humble, J. E.

1985-01-01

Studies of the arrival directions of energetic solar particles during ground level enhancements (CLE's) observed by neutron monitors have shown that, in general, in the first hour of the event most of the particles arrive with a distribution of pitch angles peaked about the garden hose field direction in the vicinity of Earth. During the first hour some of the particles arrive from the antisolar direction, while in later stages of the event the intensity becomes more nearly isotropic as a result of scattering of particles in interplanetary space. An attempt is made to determine the arrival directions of the particles during the early stages of the GLE of 16 February 1984 using the data currently available from high latitude neutron monitors near sea level where the cut off is essentially atmospheric (approx. LGV).

Review of particle physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olive, K. A.

The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 3,062 new measurements from 721 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders,more » Probability and Statistics. As a result, among the 117 reviews are many that are new or heavily revised, including those on Pentaquarks and Inflation.« less

Simultaneous velocity measurements of particle and gas phase in particle-laden co-flowing pipe jets

NASA Astrophysics Data System (ADS)

Saridakis, Isaac; Lau, Timothy; Djenidi, Lyazid; Nathan, Graham

2016-11-01

Simultaneous planar velocity measurements of both the carrier gas and particles are reported of well-characterized particle-laden co-flowing pipe jets. It is proposed to present measurements that were obtained through application of a median-filter discrimination technique to separate the Particle Image Velocimetry (PIV) signals of the 0.5 μm diameter fluid tracers from those of the larger particles of diameter 20 μm and 40 μm. Instantaneous particle and fluid planar velocity distributions were measured for three Reynold's numbers ranging from 10,000 to 40,000 and five Stokes numbers from 1 to 22, at a jet bulk fluid velocity to co-flow velocity ratio of 12. Selected results will be presented which show that the slip velocity is dependent on the local Stokes number. These are the first simultaneous carrier gas and particle velocity measurements in particle-laden jets and provide new understanding of fluid-particle interactions. Financial support from Australian Research Council and Australian Renewable Energy Agency.

Icy Particle Spray

NASA Image and Video Library

2010-11-18

Images obtained by NASA EPOXI mission spacecraft show an active end of the nucleus of comet Hartley 2. Icy particles spew from the surface. Most of these particles are traveling with the nucleus; fluffy nowballs about 3 centimeters to 30 centimeters.

Nanodisperse transition metal electrodes (NTME) for electrochemical cells

DOEpatents

Striebel, Kathryn A.; Wen, Shi-Jie

2000-01-01

Disclosed are transition metal electrodes for electrochemical cells using gel-state and solid-state polymers. The electrodes are suitable for use in primary and secondary cells. The electrodes (either negative electrode or positive electrode) are characterized by uniform dispersion of the transition metal at the nanoscale in the polymer. The transition metal moiety is structurally amorphous, so no capacity fade should occur due to lattice expansion/contraction mechanisms. The small grain size, amorphous structure and homogeneous distribution provide improved charge/discharge cycling performance, and a higher initial discharge rate capability. The cells can be cycled at high current densities, limited only by the electrolyte conductivity. A method of making the electrodes (positive and negative), and their usage in electrochemical cells are disclosed.

Effect of Finite Particle Size on Convergence of Point Particle Models in Euler-Lagrange Multiphase Dispersed Flow

NASA Astrophysics Data System (ADS)

Nili, Samaun; Park, Chanyoung; Haftka, Raphael T.; Kim, Nam H.; Balachandar, S.

2017-11-01

Point particle methods are extensively used in simulating Euler-Lagrange multiphase dispersed flow. When particles are much smaller than the Eulerian grid the point particle model is on firm theoretical ground. However, this standard approach of evaluating the gas-particle coupling at the particle center fails to converge as the Eulerian grid is reduced below particle size. We present an approach to model the interaction between particles and fluid for finite size particles that permits convergence. We use the generalized Faxen form to compute the force on a particle and compare the results against traditional point particle method. We apportion the different force components on the particle to fluid cells based on the fraction of particle volume or surface in the cell. The application is to a one-dimensional model of shock propagation through a particle-laden field at moderate volume fraction, where the convergence is achieved for a well-formulated force model and back coupling for finite size particles. Comparison with 3D direct fully resolved numerical simulations will be used to check if the approach also improves accuracy compared to the point particle model. Work supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

Rice Starch Particle Interactions at Air/Aqueous Interfaces—Effect of Particle Hydrophobicity and Solution Ionic Strength

PubMed Central

McNamee, Cathy E.; Sato, Yu; Wiege, Berthold; Furikado, Ippei; Marefati, Ali; Nylander, Tommy; Kappl, Michael; Rayner, Marilyn

2018-01-01

Starch particles modified by esterification with dicarboxylic acids to give octenyl succinic anhydride (OSA) starch is an approved food additive that can be used to stabilize oil in water emulsions used in foods and drinks. However, the effects of the OSA modification of the starch particle on the interfacial interactions are not fully understood. Here, we directly measured the packing of films of rice starch granules, i.e., the natural particle found inside the plant, at air/aqueous interfaces, and the interaction forces in that system as a function of the particle hydrophobicity and ionic strength, in order to gain insight on how starch particles can stabilize emulsions. This was achieved by using a combined Langmuir trough and optical microscope system, and the Monolayer Interaction Particle Apparatus. Native rice starch particles were seen to form large aggregates at air/water interfaces, causing films with large voids to be formed at the interface. The OSA modification of the rice starches particles decreased this aggregation. Increasing the degree of modification improved the particle packing within the film of particles at the air/water interface, due to the introduction of inter-particle electrostatic interactions within the film. The introduction of salt to the water phase caused the particles to aggregate and form holes within the film, due to the screening of the charged groups on the starch particles by the salt. The presence of these holes in the film decreased the stiffness of the films. The effect of the OSA modification was concluded to decrease the aggregation of the particles at an air/water interface. The presence of salts, however, caused the particles to aggregate, thereby reducing the strength of the interfacial film. PMID:29868551

Single-particle characterization of indoor aerosol particles collected at an underground shopping area in Seoul, Korea.

PubMed

Maskey, Shila; Kang, TaeHee; Jung, Hae-Jin; Ro, Chul-Un

2011-02-01

In this study, single-particle characterization of aerosol particles collected at an underground shopping area was performed for the first time. A quantitative single-particle analytical technique, low-Z particle electron probe X-ray microanalysis, was used to characterize a total of 7900 individual particles for eight sets of aerosol samples collected at an underground shopping area in Seoul, Korea. Based on secondary electron images and X-ray spectral data of individual particles, fourteen particle types were identified, in which primary soil-derived particles were the most abundant, followed by carbonaceous, Fe-containing, secondary soil-derived, and secondary sea-salt particles. Carbonaceous particles exist in three types: organic carbon, carbon-rich, and CNO-rich. A significant number of textile particles with chemical composition C, N, and O were encountered in some of the aerosol samples, which were from the textile shops and/or from clothes of passersby. Primary soil-derived particles showed seasonal variation, with peak values in spring samples, reflecting higher air exchange between indoor and outdoor environments in the spring. Secondary soil-derived, secondary sea-salt, and ammonium sulfate particles were frequently encountered in winter samples. Fe-containing particles, contributed from a nearby subway station, were in the range of about 19% relative abundances for all samples. In underground shopping areas, particulate matters can be a considerable health hazard to the workers, shoppers, passersby, and shop-keepers as they spend their considerable time in this closed microenvironment. However, no study on the characteristics of indoor aerosols in an underground shopping area has been reported to our knowledge. This work provides detailed information on characteristics of underground shopping area aerosols on a single particle level. © 2010 John Wiley & Sons A/S.

Rice Starch Particle Interactions at Air/Aqueous Interfaces-Effect of Particle Hydrophobicity and Solution Ionic Strength.

PubMed

McNamee, Cathy E; Sato, Yu; Wiege, Berthold; Furikado, Ippei; Marefati, Ali; Nylander, Tommy; Kappl, Michael; Rayner, Marilyn

2018-01-01

Starch particles modified by esterification with dicarboxylic acids to give octenyl succinic anhydride (OSA) starch is an approved food additive that can be used to stabilize oil in water emulsions used in foods and drinks. However, the effects of the OSA modification of the starch particle on the interfacial interactions are not fully understood. Here, we directly measured the packing of films of rice starch granules, i.e., the natural particle found inside the plant, at air/aqueous interfaces, and the interaction forces in that system as a function of the particle hydrophobicity and ionic strength, in order to gain insight on how starch particles can stabilize emulsions. This was achieved by using a combined Langmuir trough and optical microscope system, and the Monolayer Interaction Particle Apparatus. Native rice starch particles were seen to form large aggregates at air/water interfaces, causing films with large voids to be formed at the interface. The OSA modification of the rice starches particles decreased this aggregation. Increasing the degree of modification improved the particle packing within the film of particles at the air/water interface, due to the introduction of inter-particle electrostatic interactions within the film. The introduction of salt to the water phase caused the particles to aggregate and form holes within the film, due to the screening of the charged groups on the starch particles by the salt. The presence of these holes in the film decreased the stiffness of the films. The effect of the OSA modification was concluded to decrease the aggregation of the particles at an air/water interface. The presence of salts, however, caused the particles to aggregate, thereby reducing the strength of the interfacial film.

Rice starch particle interactions at air/aqueous interfaces– effect of particle hydrophobicity and solution ionic strength

NASA Astrophysics Data System (ADS)

McNamee, Cathy E.; Sato, Yu; Wiege, Berthold; Furikado, Ippei; Marefati, Ali; Nylander, Tommy; Kappl, Michael; Rayner, Marilyn

2018-05-01

Starch particles modified by esterification with dicarboxylic acids to give octenyl succinic anhydride (OSA) starch is an approved food additive that can be used to stabilize oil in water emulsions used in foods and drinks. However, the effects of the OSA modification of the starch particle on the interfacial interactions are not fully understood. Here, we directly measured the packing of films of rice starch granules, i.e. the natural particle found inside the plant, at air/aqueous interfaces and the interaction forces in that system as a function of the particle hydrophobicity and ionic strength, in order to gain insight on how starch particles can stabilize emulsions. This was achieved by using a combined Langmuir trough and optical microscope system, and the Monolayer Interaction Particle Apparatus. Native rice starch particles were seen to form large aggregates at air/water interfaces, causing films with large voids to be formed at the interface. The OSA modification of the rice starches particles decreased this aggregation. Increasing the degree of modification improved the particle packing within the film of particles at the air/water interface, due to the introduction of inter-particle electrostatic interactions within the film. The introduction of salt to the water phase caused the particles to aggregate and form holes within the film, due to the screening of the charged groups on the starch particles by the salt. The presence of these holes in the film decreased the stiffness of the films. The effect of the OSA modification was concluded to decrease the aggregation of the particles at an air/water interface. The presence of salts, however, caused the particles to aggregate, thereby reducing the strength of the interfacial film.

When is a Particle?

ERIC Educational Resources Information Center

Drell, Sidney D.

1978-01-01

Gives a new definition for the concept of the elementary particle in nuclear physics. Explains why the existance of the quark as an elementary particle could be an accepted fact even though it lacks what traditionally identifies a particle. Compares this with the development which took place during the discovery of the neutrino in the early…