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Sample records for advanced porous materials

  1. Methane storage in advanced porous materials.

    PubMed

    Makal, Trevor A; Li, Jian-Rong; Lu, Weigang; Zhou, Hong-Cai

    2012-12-01

    The need for alternative fuels is greater now than ever before. With considerable sources available and low pollution factor, methane is a natural choice as petroleum replacement in cars and other mobile applications. However, efficient storage methods are still lacking to implement the application of methane in the automotive industry. Advanced porous materials, metal-organic frameworks and porous organic polymers, have received considerable attention in sorptive storage applications owing to their exceptionally high surface areas and chemically-tunable structures. In this critical review we provide an overview of the current status of the application of these two types of advanced porous materials in the storage of methane. Examples of materials exhibiting high methane storage capacities are analyzed and methods for increasing the applicability of these advanced porous materials in methane storage technologies described.

  2. Combustion Synthesis of Advanced Porous Materials in Microgravity Environment

    NASA Technical Reports Server (NTRS)

    Zhang, X.; Moore, J. J.; Schowengerdt, F. D.; Johnson, D. P.

    1999-01-01

    Combustion synthesis, otherwise known as self-propagating high temperature synthesis (SHS), can be used to produce engineered advanced porous material implants which offer the possibility for bone ingrowth as well as a permanent structure framework for the long-term replacement of bone defects. The primary advantage of SHS is based on its rapid kinetics and favorable energetics. The structure and properties of materials produced by SHS are strongly dependent on the combustion reaction conditions. Combustion reaction conditions such as reaction stoichiometry, particle size, green density, the presence and use of diluents or inert reactants, and pre-heating of the reactants, will affect the exothermicity of the reaction. A number of conditions must be satisfied in order to obtain high porosity materials: an optimal amount of liquid, gas and solid phases must be present in the combustion front. Therefore, a balance among these phases at the combustion front must be created by the SHS reaction to successfully engineer a bone replacement material system. Microgravity testing has extended the ability to form porous products. The convective heat transfer mechanisms which operate in normal gravity, 1 g, constrain the combustion synthesis reactions. Gravity also acts to limit the porosity which may be formed as the force of gravity serves to restrict the gas expansion and the liquid movement during reaction. Infiltration of the porous product with other phases can modify both the extent of porosity and the mechanical properties.

  3. Porous graphene materials for advanced electrochemical energy storage and conversion devices.

    PubMed

    Han, Sheng; Wu, Dongqing; Li, Shuang; Zhang, Fan; Feng, Xinliang

    2014-02-12

    Combining the advantages from both porous materials and graphene, porous graphene materials have attracted vast interests due to their large surface areas, unique porous structures, diversified compositions and excellent electronic conductivity. These unordinary features enable porous graphene materials to serve as key components in high-performance electrochemical energy storage and conversion devices such as lithium ion batteries, supercapacitors, and fuel cells. This progress report summarizes the typical fabrication methods for porous graphene materials with micro-, meso-, and macro-porous structures. The structure-property relationships of these materials and their application in advanced electrochemical devices are also discussed.

  4. Advances in design and modeling of porous materials

    NASA Astrophysics Data System (ADS)

    Ayral, André; Calas-Etienne, Sylvie; Coasne, Benoit; Deratani, André; Evstratov, Alexis; Galarneau, Anne; Grande, Daniel; Hureau, Matthieu; Jobic, Hervé; Morlay, Catherine; Parmentier, Julien; Prelot, Bénédicte; Rossignol, Sylvie; Simon-Masseron, Angélique; Thibault-Starzyk, Frédéric

    2015-07-01

    This special issue of the European Physical Journal Special Topics is dedicated to selected papers from the symposium "High surface area porous and granular materials" organized in the frame of the conference "Matériaux 2014", held on November 24-28, 2014 in Montpellier, France. Porous materials and granular materials gather a wide variety of heterogeneous, isotropic or anisotropic media made of inorganic, organic or hybrid solid skeletons, with open or closed porosity, and pore sizes ranging from the centimeter scale to the sub-nanometer scale. Their technological and industrial applications cover numerous areas from building and civil engineering to microelectronics, including also metallurgy, chemistry, health, waste water and gas effluent treatment. Many emerging processes related to environmental protection and sustainable development also rely on this class of materials. Their functional properties are related to specific transfer mechanisms (matter, heat, radiation, electrical charge), to pore surface chemistry (exchange, adsorption, heterogeneous catalysis) and to retention inside confined volumes (storage, separation, exchange, controlled release). The development of innovative synthesis, shaping, characterization and modeling approaches enables the design of advanced materials with enhanced functional performance. The papers collected in this special issue offer a good overview of the state-of-the-art and science of these complex media. We would like to thank all the speakers and participants for their contribution to the success of the symposium. We also express our gratitude to the organization committee of "Matériaux 2014". We finally thank the reviewers and the staff of the European Physical Journal Special Topics who made the publication of this special issue possible.

  5. Advances in monoliths and related porous materials for microfluidics.

    PubMed

    Knob, Radim; Sahore, Vishal; Sonker, Mukul; Woolley, Adam T

    2016-05-01

    In recent years, the use of monolithic porous polymers has seen significant growth. These materials present a highly useful support for various analytical and biochemical applications. Since their introduction, various approaches have been introduced to produce monoliths in a broad range of materials. Simple preparation has enabled their easy implementation in microchannels, extending the range of applications where microfluidics can be successfully utilized. This review summarizes progress regarding monoliths and related porous materials in the field of microfluidics between 2010 and 2015. Recent developments in monolith preparation, solid-phase extraction, separations, and catalysis are critically discussed. Finally, a brief overview of the use of these porous materials for analysis of subcellular and larger structures is given. PMID:27190564

  6. Gravitational Effects on Combustion Synthesis of Advanced Porous Materials

    NASA Technical Reports Server (NTRS)

    Zhang, X.; Moore, J. J.; Schowengerdt, F. D.; Thorne, K.

    2000-01-01

    Combustion Synthesis (self-Propagating high-temperature synthesis-(SHS)) of porous Ti-TiB(x), composite materials has been studied with respect to the sensitivity to the SHS reaction parameters of stoichiometry, green density, gasifying agents, ambient pressure, diluents and gravity. The main objective of this research program is to engineer the required porosity and mechanical properties into the composite materials to meet the requirements of a consumer, such as for the application of bone replacement materials. Gravity serves to restrict the gas expansion and the liquid movement during SHS reaction. As a result, gravitational forces affect the microstructure and properties of the SHS products. Reacting these SHS systems in low gravity in the KC-135 aircraft has extended the ability to form porous products. This paper will emphasize the effects of gravity (low g, 1g and 2g) on the SHS reaction process, and the microstructure and properties of the porous composite. Some of biomedical results are also discussed.

  7. Advanced Porous Coating for Low-Density Ceramic Insulation Materials

    NASA Technical Reports Server (NTRS)

    Leiser, Daniel B.; Churchward, Rex; Katvala, Victor; Stewart, David; Balter, Aliza

    1988-01-01

    The need for improved coatings on low-density reusable surface insulation (RSI) materials used on the space shuttle has stimulated research into developing tougher coatings. The processing of a new porous composite "coating" for RST called toughened unipiece fibrous insulation Is discussed. Characteristics including performance in a simulated high-speed atmospheric entry, morphological structure before and after this exposure, resistance to Impact, and thermal response to a typical heat pulse are described. It is shown that this coating has improved impact resistance while maintaining optical and thermal properties comparable to the previously available reaction-cured glass coating.

  8. Design of advanced porous graphene materials: from graphene nanomesh to 3D architectures.

    PubMed

    Jiang, Lili; Fan, Zhuangjun

    2014-02-21

    In order to make full utilization of the high intrinsic surface area of graphene, recently, porous graphene materials including graphene nanomesh, crumpled graphene and graphene foam, have attracted tremendous attention and research interest, owing to their exceptional porous structure (high surface area, and high pore volume) in combination with the inherent properties of graphene, such as high electronic conductivity, good thermal stability, and excellent mechanical strength. Interestingly, porous graphene materials and their derivatives have been explored in a wide range of applications in the fields of electronic and photonic devices, energy storage, gas separation/storage, oil absorption and sensors. This article reviews recent progress in the synthesis, characterization, properties, and applications of porous graphene materials. We aim to highlight the importance of designing different porous structures of graphene to meet future challenges, and the trend on future design of porous graphene materials is analyzed.

  9. Design of advanced porous graphene materials: from graphene nanomesh to 3D architectures

    NASA Astrophysics Data System (ADS)

    Jiang, Lili; Fan, Zhuangjun

    2014-01-01

    In order to make full utilization of the high intrinsic surface area of graphene, recently, porous graphene materials including graphene nanomesh, crumpled graphene and graphene foam, have attracted tremendous attention and research interest, owing to their exceptional porous structure (high surface area, and high pore volume) in combination with the inherent properties of graphene, such as high electronic conductivity, good thermal stability, and excellent mechanical strength. Interestingly, porous graphene materials and their derivatives have been explored in a wide range of applications in the fields of electronic and photonic devices, energy storage, gas separation/storage, oil absorption and sensors. This article reviews recent progress in the synthesis, characterization, properties, and applications of porous graphene materials. We aim to highlight the importance of designing different porous structures of graphene to meet future challenges, and the trend on future design of porous graphene materials is analyzed.

  10. Tailored Porous Materials

    SciTech Connect

    BARTON,THOMAS J.; BULL,LUCY M.; KLEMPERER,WALTER G.; LOY,DOUGLAS A.; MCENANEY,BRIAN; MISONO,MAKOTO; MONSON,PETER A.; PEZ,GUIDO; SCHERER,GEORGE W.; VARTULI,JAMES C.; YAGHI,OMAR M.

    1999-11-09

    Tailoring of porous materials involves not only chemical synthetic techniques for tailoring microscopic properties such as pore size, pore shape, pore connectivity, and pore surface reactivity, but also materials processing techniques for tailoring the meso- and the macroscopic properties of bulk materials in the form of fibers, thin films and monoliths. These issues are addressed in the context of five specific classes of porous materials: oxide molecular sieves, porous coordination solids, porous carbons, sol-gel derived oxides, and porous heteropolyanion salts. Reviews of these specific areas are preceded by a presentation of background material and review of current theoretical approaches to adsorption phenomena. A concluding section outlines current research needs and opportunities.

  11. Nitrogen-doped porous graphitic carbon as an excellent electrode material for advanced supercapacitors.

    PubMed

    Sun, Li; Tian, Chungui; Fu, Yu; Yang, Ying; Yin, Jie; Wang, Lei; Fu, Honggang

    2014-01-01

    An advanced supercapacitor material based on nitrogen-doped porous graphitic carbon (NPGC) with high a surface area was synthesized by means of a simple coordination-pyrolysis combination process, in which tetraethyl orthosilicate (TEOS), nickel nitrate, and glucose were adopted as porogent, graphitic catalyst precursor, and carbon source, respectively. In addition, melamine was selected as a nitrogen source owing to its nitrogen-enriched structure and the strong interaction between the amine groups and the glucose unit. A low-temperature treatment resulted in the formation of a NPGC precursor by combination of the catalytic precursor, hydrolyzed TEOS, and the melamine-glucose unit. Following pyrolysis and removal of the catalyst and porogent, the NPGC material showed excellent electrical conductivity owing to its high crystallinity, a large Brunauer-Emmett-Teller surface area (SBET =1027 m(2)  g(-1) ), and a high nitrogen level (7.72 wt %). The unusual microstructure of NPGC materials could provide electrochemical energy storage. The NPGC material, without the need for any conductive additives, showed excellent capacitive behavior (293 F g(-1) at 1 A g(-1) ), long-term cycling stability, and high coulombic efficiency (>99.9 % over 5000 cycles) in KOH when used as an electrode. Notably, in a two-electrode symmetric supercapacitor, NPGC energy densities as high as 8.1 and 47.5 Wh kg(-1) , at a high power density (10.5 kW kg(-1) ), were achieved in 6 M KOH and 1 M Et4 NBF4 -PC electrolytes, respectively. Thus, the synthesized NPGC material could be a highly promising electrode material for advanced supercapacitors and other conversion devices.

  12. Recent advances in porous polyoxometalate-based metal-organic framework materials.

    PubMed

    Du, Dong-Ying; Qin, Jun-Sheng; Li, Shun-Li; Su, Zhong-Min; Lan, Ya-Qian

    2014-07-01

    Polyoxometalate (POM)-based metal-organic framework (MOF) materials contain POM units and generally generate MOF materials with open networks. POM-based MOF materials, which utilize the advantages of both POMs and MOFs, have received increasing attention, and much effort has been devoted to their preparation and relevant applications over the past few decades. They have good prospects in catalysis owing to the electronic and physical properties of POMs that are tunable by varying constituent elements. In this review, we present recent developments in porous POM-based MOF materials, including their classification, synthesis strategies, and applications, especially in the field of catalysis. PMID:24676127

  13. Preparation of asymmetric porous materials

    DOEpatents

    Coker, Eric N.

    2012-08-07

    A method for preparing an asymmetric porous material by depositing a porous material film on a flexible substrate, and applying an anisotropic stress to the porous media on the flexible substrate, where the anisotropic stress results from a stress such as an applied mechanical force, a thermal gradient, and an applied voltage, to form an asymmetric porous material.

  14. Porous material neutron detector

    DOEpatents

    Diawara, Yacouba; Kocsis, Menyhert

    2012-04-10

    A neutron detector employs a porous material layer including pores between nanoparticles. The composition of the nanoparticles is selected to cause emission of electrons upon detection of a neutron. The nanoparticles have a maximum dimension that is in the range from 0.1 micron to 1 millimeter, and can be sintered with pores thereamongst. A passing radiation generates electrons at one or more nanoparticles, some of which are scattered into a pore and directed toward a direction opposite to the applied electrical field. These electrons travel through the pore and collide with additional nanoparticles, which generate more electrons. The electrons are amplified in a cascade reaction that occurs along the pores behind the initial detection point. An electron amplification device may be placed behind the porous material layer to further amplify the electrons exiting the porous material layer.

  15. Strong, Lightweight, Porous Materials

    NASA Technical Reports Server (NTRS)

    Leventis, Nicholas; Meador, Mary Ann B.; Johnston, James C.; Fabrizio, Eve F.; Ilhan, Ulvi

    2007-01-01

    A new class of strong, lightweight, porous materials has been invented as an outgrowth of an effort to develop reinforced silica aerogels. The new material, called X-Aerogel is less hygroscopic, but no less porous and of similar density to the corresponding unmodified aerogels. However, the property that sets X-Aerogels apart is their mechanical strength, which can be as much as two and a half orders of magnitude stronger that the unmodified aerogels. X-Aerogels are envisioned to be useful for making extremely lightweight, thermally insulating, structural components, but they may also have applications as electrical insulators, components of laminates, catalyst supports, templates for electrode materials, fuel-cell components, and filter membranes.

  16. Porous bioactive materials

    NASA Astrophysics Data System (ADS)

    Zhang, Kai

    Bioactive materials chemically bond to tissues through the development of biologically active apatite. Porous structures in biomaterials are designed to enhance bioactivity, grow artificial tissues and achieve better integration with host tissues in the body. The goal of this research is to design, fabricate and characterize novel porous bioactive materials. 3D ordered macroporous bioactive glasses (3DOM-BGs, pore size: 200--1000 nm) were prepared using a sol-gel process and colloidal crystal templates. 3DOM-BGs are more bioactive and degradable than mesoporous (pore size <50 nm) sol-gel BGs in simulated body fluid (SBF). Apatite formation and 3DOM-BG degradation rates increased with the decrease of soaking ratio. Apatite induction time in SBF increased with 3DOM-BG calcination temperature (600--800°C). Apatite formation and 3DOMBG degradation were slightly enhanced for a phosphate containing composition. Large 3DOM-BG particles formed less apatite and degraded less completely as compared with small particles. An increase in macropore size slowed down 3DOM-BG degradation and apatite formation processes. After heating the converted apatite at a temperature higher than 700°C, highly crystalline hydroxyapatite and a minor tri-calcium phosphate phase formed. 3DOM-BGs have potential applications as bone/periodontal fillers, and drugs and biological factors delivery agents. Anchoring artificial soft tissues (e.g., cartilage) to native bone presents a challenge. Porous polymer/bioactive glass composites are candidate materials for engineering artificial soft tissue/bone interfaces. Porous composites consisting of polymer matrices (e.g., polysulfone, polylactide, and polyurethane) and bioactive glass particles were prepared by polymer phase separation techniques adapted to include ceramic particles. Composites (thickness: 200--500 mum) have asymmetric structures with dense top layers and porous structures beneath. Porous structures consist of large pores (>100 mum) in a

  17. Porous materials. Function-led design of new porous materials.

    PubMed

    Slater, Anna G; Cooper, Andrew I

    2015-05-29

    Porous solids are important as membranes, adsorbents, catalysts, and in other chemical applications. But for these materials to find greater use at an industrial scale, it is necessary to optimize multiple functions in addition to pore structure and surface area, such as stability, sorption kinetics, processability, mechanical properties, and thermal properties. Several different classes of porous solids exist, and there is no one-size-fits-all solution; it can therefore be challenging to choose the right type of porous material for a given job. Computational prediction of structure and properties has growing potential to complement experiment to identify the best porous materials for specific applications.

  18. Ordered porous materials for emerging applications.

    PubMed

    Davis, Mark E

    2002-06-20

    "Space--the final frontier." This preamble to a well-known television series captures the challenge encountered not only in space travel adventures, but also in the field of porous materials, which aims to control the size, shape and uniformity of the porous space and the atoms and molecules that define it. The past decade has seen significant advances in the ability to fabricate new porous solids with ordered structures from a wide range of different materials. This has resulted in materials with unusual properties and broadened their application range beyond the traditional use as catalysts and adsorbents. In fact, porous materials now seem set to contribute to developments in areas ranging from microelectronics to medical diagnosis.

  19. Advances in modeling sorption and diffusion of moisture in porous reactive materials.

    PubMed

    Harley, Stephen J; Glascoe, Elizabeth A; Lewicki, James P; Maxwell, Robert S

    2014-06-23

    Water-vapor-uptake experiments were performed on a silica-filled poly(dimethylsiloxane) (PDMS) network and modeled by using two different approaches. The data was modeled by using established methods and the model parameters were used to predict moisture uptake in a sample. The predictions are reasonably good, but not outstanding; many of the shortcomings of the modeling are discussed. A high-fidelity modeling approach is derived and used to improve the modeling of moisture uptake and diffusion. Our modeling approach captures the physics and kinetics of diffusion and adsorption/desorption, simultaneously. It predicts uptake better than the established method; more importantly, it is also able to predict outgassing. The material used for these studies is a filled-PDMS network; physical interpretations concerning the sorption and diffusion of moisture in this network are discussed.

  20. Acoustic Absorption in Porous Materials

    NASA Technical Reports Server (NTRS)

    Kuczmarski, Maria A.; Johnston, James C.

    2011-01-01

    An understanding of both the areas of materials science and acoustics is necessary to successfully develop materials for acoustic absorption applications. This paper presents the basic knowledge and approaches for determining the acoustic performance of porous materials in a manner that will help materials researchers new to this area gain the understanding and skills necessary to make meaningful contributions to this field of study. Beginning with the basics and making as few assumptions as possible, this paper reviews relevant topics in the acoustic performance of porous materials, which are often used to make acoustic bulk absorbers, moving from the physics of sound wave interactions with porous materials to measurement techniques for flow resistivity, characteristic impedance, and wavenumber.

  1. Single electrospun porous NiO-ZnO hybrid nanofibers as anode materials for advanced lithium-ion batteries.

    PubMed

    Qiao, Li; Wang, Xinghui; Qiao, Li; Sun, Xiaolei; Li, Xiuwan; Zheng, Yunxian; He, Deyan

    2013-04-01

    Porous NiO-ZnO hybrid nanofibers were prepared by a single-nozzle electrospinning technique combined with subsequent heating treatment. The resultant nanofibers are composed of interconnected primary nanocrystals and numerous nanopores with heterostructures between NiO and ZnO. Such characteristics of the structure can lead to excellent electrochemical performances when the nanofiber was evaluated as an anode material for lithium-ion batteries. The porous NiO-ZnO nanofiber electrode delivers a high discharge capacity of 949 mA h g(-1) after 120 cycles at 0.2 A g(-1), and maintains around 707 mA h g(-1) at a current density as high as 3.2 A g(-1). Even after cycling at high rates, the electrode still retains a high discharge capacity of up to 1185 mA h g(-1) at 0.2 A g(-1).

  2. Metal recovery from porous materials

    DOEpatents

    Sturcken, Edward F.

    1992-01-01

    A method for recovering plutonium and other metals from materials by leaching comprising the steps of incinerating the materials to form a porous matrix as the residue of incineration, immersing the matrix into acid in a microwave-transparent pressure vessel, sealing the pressure vessel, and applying microwaves so that the temperature and the pressure in the pressure vessel increase. The acid for recovering plutonium can be a mixture of HBF.sub.4 and HNO.sub.3 and preferably the pressure is increased to at least 100 PSI and the temperature to at least 200.degree. C. The porous material can be pulverized before immersion to further increase the leach rate.

  3. Metal recovery from porous materials

    DOEpatents

    Sturcken, E.F.

    1991-01-01

    The present invention relates to recovery of metals. More specifically, the present invention relates to the recovery of plutonium and other metals from porous materials using microwaves. The United States Government has rights in this invention pursuant to Contract No. DE-AC09-89SR18035 between the US Department of Energy and Westinghouse Savannah River Company.

  4. Metal recovery from porous materials

    DOEpatents

    Sturcken, E.F.

    1992-10-13

    A method is described for recovering plutonium and other metals from materials by leaching comprising the steps of incinerating the materials to form a porous matrix as the residue of incineration, immersing the matrix into acid in a microwave-transparent pressure vessel, sealing the pressure vessel, and applying microwaves so that the temperature and the pressure in the pressure vessel increase. The acid for recovering plutonium can be a mixture of HBF[sub 4] and HNO[sub 3] and preferably the pressure is increased to at least 100 PSI and the temperature to at least 200 C. The porous material can be pulverized before immersion to further increase the leach rate.

  5. Microwave impregnation of porous materials with thermal energy storage materials

    DOEpatents

    Benson, David K.; Burrows, Richard W.

    1993-01-01

    A method for impregnating a porous, non-metallic construction material with a solid phase-change material is described. The phase-change material in finely divided form is spread onto the surface of the porous material, after which the porous material is exposed to microwave energy for a time sufficient to melt the phase-change material. The melted material is spontaneously absorbed into the pores of the porous material. A sealing chemical may also be included with the phase-change material (or applied subsequent to the phase-change material) to seal the surface of the porous material. Fire retardant chemicals may also be included with the phase-change materials. The treated construction materials are better able to absorb thermal energy and exhibit increased heat storage capacity.

  6. Microwave impregnation of porous materials with thermal energy storage materials

    DOEpatents

    Benson, D.K.; Burrows, R.W.

    1993-04-13

    A method for impregnating a porous, non-metallic construction material with a solid phase-change material is described. The phase-change material in finely divided form is spread onto the surface of the porous material, after which the porous material is exposed to microwave energy for a time sufficient to melt the phase-change material. The melted material is spontaneously absorbed into the pores of the porous material. A sealing chemical may also be included with the phase-change material (or applied subsequent to the phase-change material) to seal the surface of the porous material. Fire retardant chemicals may also be included with the phase-change materials. The treated construction materials are better able to absorb thermal energy and exhibit increased heat storage capacity.

  7. Microwave impregnation of porous materials with thermal energy storage materials

    SciTech Connect

    Benson, D.K.; Burrows, R.W.

    1991-03-13

    A method for impregnating a porous, non-metallic construction material with a solid phase-change material is described. The phase-change material in finely divided form is spread onto the surface of the porous material, after which the porous material is exposed to microwave energy for a time sufficient to melt the phase-change material. The melted material is spontaneously absorbed into the pores of the porous material. A sealing chemical may also be included with the phase-change material (or applied subsequent tc the phase-change material) to seal the surface of the porous material. Fire retardant chemicals may also be included with the phase-change materials. The treated construction materials are better able to absorb thermal energy and exhibit increased heat storage capacity.

  8. Microwave impregnation of porous materials with thermal energy storage materials

    SciTech Connect

    Benson, D.K.; Burrows, R.W.

    1992-12-31

    A method for impregnating a porous, non-metallic construction material with a solid phase-change material is described. The phase-change material in finely divided form is spread onto the surface of the porous material, after which the porous material is exposed to microwave energy for a time sufficient to melt the phase-change material. The melted material is spontaneously absorbed into the pores of the porous material. A sealing chemical may also be included with the phase-change material (or applied subsequent to the phase-change material) to seal the surface of the porous material. Fire retardant chemicals may also be included with the phase-change materials. The treated construction materials are better able to absorb thermal energy and exhibit increased heat storage capacity.

  9. Anatase TiO2@C composites with porous structure as an advanced anode material for Na ion batteries

    NASA Astrophysics Data System (ADS)

    Shi, Xiaodong; Zhang, Zhian; Du, Ke; Lai, Yanqing; Fang, Jing; Li, Jie

    2016-10-01

    In this paper, we propose a facile strategy to synthesize the porous structure TiO2@C composites through a two-step method, in which the precursor of MIL-125(Ti) was firstly prepared by solvent thermal method and then calcined under inert atmosphere. When employed as anodes for Na ion batteries, TiO2@C composites can exhibit a superior cyclability with a reversible sodium storage capacity of 148 mAh g-1 at the current density 0.5 A g-1 after 500 cycles and an excellent rate performance with a capacity of 88.9 mAh g-1 even the current reached to 2.5 A g-1 due to the dispersion of anatase TiO2 throughout amorphous carbon matrix and the synergistic effect between the anatase TiO2 nanocrystals and carbon matrix, which can availably enhance the electric conductivity and alleviate the volumetric variation of TiO2 during the insertion/extraction process of Na+.

  10. Porous nano-structured Co3O4 anode materials generated from coordination-driven self-assembled aggregates for advanced lithium ion batteries.

    PubMed

    Ge, Danhua; Geng, Hongbo; Wang, Jiaqing; Zheng, Junwei; Pan, Yue; Cao, Xueqin; Gu, Hongwei

    2014-08-21

    A simple and scalable coordination-derived method for the synthesis of porous Co3O4 hollow nanospheres is described here. The initially formed coordination-driven self-assembled aggregates (CDSAAs) could act as the precursor followed by calcination treatment. Then the porous hollow Co3O4 nanospheres are obtained, in which the primary Co3O4 nanoparticles are inter-dispersed. When the nanospheres are used as anode materials for lithium storage, they show excellent coulombic efficiency, high lithium storage capacity and superior cycling performance. In view of the facile synthesis and excellent electrochemical performance obtained, this protocol to fabricate special porous hollow frameworks could be further extended to other metal oxides and is expected to improve the practicality of superior cycle life anode materials with large volume excursions for the development of the next generation of LIBs.

  11. Magnetic and porous molecule-based materials.

    PubMed

    Roques, Nans; Mugnaini, Veronica; Veciana, Jaume

    2010-01-01

    In this chapter, we give an overview of the recent state-of-the-art research of porous and magnetic molecule-based materials. The subject is introduced by a section devoted to the fundamentals of magnetism in molecular magnets, with special attention to the design strategies to prepare molecular magnetic materials. We will then focus on the two main families of materials combining porosity and magnetism: the purely organic and the metal-organic porous magnetic materials. For both families, a selection of the most representative examples has been made. A complete section is devoted to magnetic and porous materials with flexible frameworks, an area of emerging importance in this field, because of their wide range of applications. Finally, we conclude with a brief overview on the most recent approaches for the future development of these materials.

  12. Porous polymeric materials for hydrogen storage

    DOEpatents

    Yu, Luping; Liu, Di-Jia; Yuan, Shengwen; Yang, Junbing

    2013-04-02

    A porous polymer, poly-9,9'-spirobifluorene and its derivatives for storage of H.sub.2 are prepared through a chemical synthesis method. The porous polymers have high specific surface area and narrow pore size distribution. Hydrogen uptake measurements conducted for these polymers determined a higher hydrogen storage capacity at the ambient temperature over that of the benchmark materials. The method of preparing such polymers, includes oxidatively activating solids by CO.sub.2/steam oxidation and supercritical water treatment.

  13. Macroscopic strain potentials in nonlinear porous materials

    NASA Astrophysics Data System (ADS)

    Yi, Liu; Zhuping, Huang

    2003-02-01

    By taking a hollow sphere as a representative volume element (RVE), the macroscopic strain potentials of porous materials with power-law incompressible matrix are studied in this paper. According to the principles of the minimum potential energy in nonlinear elasticity and the variational procedure, static admissible stress fields and kinematic admissible displacement fields are constructed, and hence the upper and the lower bounds of the macroscopic strain potential are obtained. The bounds given in the present paper differ so slightly that they both provide perfect approximations of the exact strain potential of the studied porous materials. It is also found that the upper bound proposed by previous authors is much higher than the present one, and the lower bounds given by Cocks is much lower. Moreover, the present calculation is also compared with the variational lower bound of Ponte Castañeda for statistically isotropic porous materials. Finally, the validity of the hollow spherical RVE for the studied nonlinear porous material is discussed by the difference between the present numerical results and the Cocks bound.

  14. Porous polymeric materials for hydrogen storage

    DOEpatents

    Yu, Luping; Liu, Di-Jia; Yuan, Shengwen; Yang, Junbing

    2011-12-13

    Porous polymers, tribenzohexazatriphenylene, poly-9,9'-spirobifluorene, poly-tetraphenyl methane and their derivatives for storage of H.sub.2 prepared through a chemical synthesis method. The porous polymers have high specific surface area and narrow pore size distribution. Hydrogen uptake measurements conducted for these polymers determined a higher hydrogen storage capacity at the ambient temperature over that of the benchmark materials. The method of preparing such polymers, includes oxidatively activating solids by CO.sub.2/steam oxidation and supercritical water treatment.

  15. An adaptable peptide-based porous material.

    PubMed

    Rabone, J; Yue, Y-F; Chong, S Y; Stylianou, K C; Bacsa, J; Bradshaw, D; Darling, G R; Berry, N G; Khimyak, Y Z; Ganin, A Y; Wiper, P; Claridge, J B; Rosseinsky, M J

    2010-08-27

    Porous materials find widespread application in storage, separation, and catalytic technologies. We report a crystalline porous solid with adaptable porosity, in which a simple dipeptide linker is arranged in a regular array by coordination to metal centers. Experiments reinforced by molecular dynamics simulations showed that low-energy torsions and displacements of the peptides enabled the available pore volume to evolve smoothly from zero as the guest loading increased. The observed cooperative feedback in sorption isotherms resembled the response of proteins undergoing conformational selection, suggesting an energy landscape similar to that required for protein folding. The flexible peptide linker was shown to play the pivotal role in changing the pore conformation.

  16. Porous graphene materials for water remediation.

    PubMed

    Niu, Zhiqiang; Liu, Lili; Zhang, Li; Chen, Xiaodong

    2014-09-10

    Water remediation has been a critical issue over the past decades due to the expansion of wastewater discharge to the environment. Currently, a variety of functional materials have been successfully prepared for water remediation applications. Among them, graphene is an attractive candidate due to its high specific surface area, tunable surface behavior, and high strength. This Concept paper summarizes the design strategy of porous graphene materials and their applications in water remediation, such as the cleanup of oil, removal of heavy metal ions, and elimination of water soluble organic contaminants. The progress made so far will guide further development in structure design strategy of porous materials based on graphene and exploration of such materials in environmental remediation.

  17. Open-cell glass crystalline porous material

    DOEpatents

    Anshits, Alexander G.; Sharonova, Olga M.; Vereshchagina, Tatiana A.; Zykova, Irina D.; Revenko, Yurii A.; Tretyakov, Alexander A.; Aloy, Albert S.; Lubtsev, Rem I.; Knecht, Dieter A.; Tranter, Troy J.; Macheret, Yevgeny

    2003-12-23

    An open-cell glass crystalline porous material made from hollow microspheres which are cenospheres obtained from fly ash, having an open-cell porosity of up to 90 vol. % is produced. The cenospheres are separated into fractions based on one or more of grain size, density, magnetic or non-magnetic, and perforated or non-perforated. Selected fractions are molded and agglomerated by sintering with a binder at a temperature below the softening temperature, or without a binder at a temperature about, or above, the softening temperature but below the temperature of liquidity. The porous material produced has an apparent density of 0.3-0.6 g/cm.sup.3, a compressive strength in the range of 1.2-3.5 MPa, and two types of openings: through-flow wall pores in the cenospheres of 0.1-30 micrometers, and interglobular voids between the cenospheres of 20-100 micrometers. The porous material of the invention has properties useful as porous matrices for immobilization of liquid radioactive waste, heat-resistant traps and filters, supports for catalysts, adsorbents and ion-exchangers.

  18. Open-cell glass crystalline porous material

    DOEpatents

    Anshits, Alexander G.; Sharonova, Olga M.; Vereshchagina, Tatiana A.; Zykova, Irina D.; Revenko, Yurii A.; Tretyakov, Alexander A.; Aloy, Albert S.; Lubtsev, Rem I.; Knecht, Dieter A.; Tranter, Troy J.; Macheret, Yevgeny

    2002-01-01

    An open-cell glass crystalline porous material made from hollow microspheres which are cenospheres obtained from fly ash, having an open-cell porosity of up to 90 vol. % is produced. The cenospheres are separated into fractions based on one or more of grain size, density, magnetic or non-magnetic, and perforated or non-perforated. Selected fractions are molded and agglomerated by sintering with a binder at a temperature below the softening temperature, or without a binder at a temperature about, or above, the softening temperature but below the temperature of liquidity. The porous material produced has an apparent density of 0.3-0.6 g/cm.sup.3, a compressive strength in the range of 1.2-3.5 MPa, and two types of openings: through-flow wall pores in the cenospheres of 0.1-30 micrometers, and interglobular voids between the cenospheres of 20-100 micrometers. The porous material of the invention has properties useful as porous matrices for immobilization of liquid radioactive waste, heat-resistant traps and filters, supports for catalysts, adsorbents and ion-exchangers.

  19. Filter casting nanoscale porous materials

    DOEpatents

    Hayes, Joel Ryan; Nyce, Gregory Walker; Kuntz, Joshua David

    2012-07-24

    A method of producing nanoporous material includes the steps of providing a liquid, providing nanoparticles, producing a slurry of the liquid and the nanoparticles, removing the liquid from the slurry, and producing a monolith.

  20. Filter casting nanoscale porous materials

    DOEpatents

    Hayes, Joel Ryan; Nyce, Gregory Walker; Kuntz, Jushua David

    2013-12-10

    A method of producing nanoporous material includes the steps of providing a liquid, providing nanoparticles, producing a slurry of the liquid and the nanoparticles, removing the liquid from the slurry, and producing monolith.

  1. Activation of porous MOF materials

    SciTech Connect

    Hupp, Joseph T; Farha, Omar K

    2013-04-23

    A method for the treatment of solvent-containing MOF material to increase its internal surface area involves introducing a liquid into the MOF in which liquid the solvent is miscible, subjecting the MOF to supercritical conditions for a time to form supercritical fluid, and releasing the supercritical conditions to remove the supercritical fluid from the MOF. Prior to introducing the liquid into the MOF, occluded reaction solvent, such as DEF or DMF, in the MOF can be exchanged for the miscible solvent.

  2. Activation of porous MOF materials

    SciTech Connect

    Hupp, Joseph T; Farha, Omar K

    2014-04-01

    A method for the treatment of solvent-containing MOF material to increase its internal surface area involves introducing a liquid into the MOF in which liquid the solvent is miscible, subjecting the MOF to supercritical conditions for a time to form supercritical fluid, and releasing the supercritical conditions to remove the supercritcal fluid from the MOF. Prior to introducing the liquid into the MOF, occluded reaction solvent, such as DEF or DMF, in the MOF can be exchanged for the miscible solvent.

  3. Porous material for protection from electromagnetic radiation

    SciTech Connect

    Kazmina, Olga E-mail: bdushkina89@mail.ru; Dushkina, Maria E-mail: bdushkina89@mail.ru; Suslyaev, Valentin; Semukhin, Boris

    2014-11-14

    It is shown that the porous glass crystalline material obtained by a low temperature technology can be used not only for thermal insulation, but also for lining of rooms as protective screens decreasing harmful effect of electromagnetic radiation as well as to establish acoustic chambers and rooms with a low level of electromagnetic background. The material interacts with electromagnetic radiation by the most effective way in a high frequency field (above 100 GHz). At the frequency of 260 GHz the value of the transmission coefficient decreases approximately in a factor times in comparison with foam glass.

  4. Porous Materials Reinforced by Statistically Oriented Fibres

    NASA Astrophysics Data System (ADS)

    Federico, Salvatore; Grillo, Alfio

    2010-09-01

    Hydrated soft biological tissues, such as articular cartilage, are well represented by a porous matrix saturated by a fluid and reinforced by a network of statistically oriented, impermeable collagen fibres. A previously developed homogenisation method for porous fibre-reinforced materials with an isotropic matrix, under small deformations, was capable of correctly predicting some specific aspects of the anisotropy and inhomogeneity of the permeability in the tissue. The aim of this work is to generalise this model to the case of large deformations. This is achieved by means of a rescaled pull-back of the structure tensor describing fibre orientation, and directional averaging methods allowing to account for the statistical distribution of the orientation. The resulting permeability tensor contains an integral term that must be implemented numerically, because of the explicit presence of the deformation in the integrand function.

  5. Mechanical properties of a porous mullite material

    NASA Technical Reports Server (NTRS)

    Viens, Michael J.

    1991-01-01

    Modulus of rupture specimens were used to determine crack growth parameters of a porous mullite material. Strength testing was performed in ambient and moist environments. The power law crack growth rate parameters n and 1n B in 50 percent relative humidity were found to be 44.98 and 0.94, respectively. The inert strength, fracture toughness, and elastic modulus were also determined and found to be 19 MPa, 055 MPa(m) exp 1/2, and 11.6 GPa, respectively.

  6. Designing and modeling doubly porous polymeric materials

    NASA Astrophysics Data System (ADS)

    Ly, H.-B.; Le Droumaguet, B.; Monchiet, V.; Grande, D.

    2015-07-01

    Doubly porous organic materials based on poly(2-hydroxyethyl methacrylate) are synthetized through the use of two distinct types of porogen templates, namely a macroporogen and a nanoporogen. Two complementary strategies are implemented by using either sodium chloride particles or fused poly(methyl methacrylate) beads as macroporogens, in conjunction with ethanol as a porogenic solvent. The porogen removal respectively allows for the generation of either non-interconnected or interconnected macropores with an average diameter of about 100-200 μm and nanopores with sizes lying within the 100 nm order of magnitude, as evidenced by mercury intrusion porosimetry and scanning electron microscopy. Nitrogen sorption measurements evidence the formation of materials with rather high specific surface areas, i.e. higher than 140 m2.g-1. This paper also addresses the development of numerical tools for computing the permeability of such doubly porous materials. Due to the coexistence of well separated scales between nanopores and macropores, a consecutive double homogenization approach is proposed. A nanoscopic scale and a mesoscopic scale are introduced, and the flow is evaluated by means of the Finite Element Method to determine the macroscopic permeability. At the nanoscopic scale, the flow is described by the Stokes equations with an adherence condition at the solid surface. At the mesoscopic scale, the flow obeys the Stokes equations in the macropores and the Darcy equation in the permeable polymer in order to account for the presence of the nanopores.

  7. Acoustical properties of highly porous fibrous materials

    NASA Technical Reports Server (NTRS)

    Lambert, R. F.

    1979-01-01

    Highly porous, fibrous bulk sound absorbing materials are studied with a view toward understanding their acoustical properties and performance in a wide variety of applications including liners of flow ducts. The basis and criteria for decoupling of acoustic waves in the pores of the frame and compressional waves in the frame structure are established. The equations of motion are recast in a form that elucidates the coupling mechanisms. The normal incidence surface impedance and absorption coefficient of two types of Kevlar 29 and an open celled foam material are studied. Experimental values and theoretical results are brought into agreement when the structure factor is selected to provide a fit to the experimental data. A parametric procedure for achieving that fit is established. Both a bulk material quality factor and a high frequency impedance level are required to characterize the real and imaginary part of the surface impedance and absorption coefficient. A derivation of the concepts of equivalent density and dynamic resistance is presented.

  8. Wire Cloth as Porous Material for Transpiration-cooled Walls

    NASA Technical Reports Server (NTRS)

    Eckert, E R G; Kinsler, Martin R; Cochran, Reeves B

    1951-01-01

    The permeability characteristics and tensile strength of a porous material developed from stainless-steel corduroy wire cloth for use in transpiration-cooled walls where the primary stresses are in one direction were investigated. The results of this investigation are presented and compared with similar results obtained with porous sintered metal compacts. A much wider range of permeabilities is obtainable with the wire cloth than with the porous metal compacts considered and the ultimate tensile strength in the direction of the primary stresses for porous materials produced from three mesh sizes of wire cloth are from two to three times the ultimate tensile strengths of the porous metal compacts.

  9. Porous silicon advances in drug delivery and immunotherapy

    PubMed Central

    Savage, D; Liu, X; Curley, S; Ferrari, M; Serda, RE

    2013-01-01

    Biomedical applications of porous silicon include drug delivery, imaging, diagnostics and immunotherapy. This review summarizes new silicon particle fabrication techniques, dynamics of cellular transport, advances in the multistage vector approach to drug delivery, and the use of porous silicon as immune adjuvants. Recent findings support superior therapeutic efficacy of the multistage vector approach over single particle drug delivery systems in mouse models of ovarian and breast cancer. With respect to vaccine development, multivalent presentation of pathogen-associated molecular patterns on the particle surface creates powerful platforms for immunotherapy, with the porous matrix able to carry both antigens and immune modulators. PMID:23845260

  10. Molecular Rotors Built in Porous Materials.

    PubMed

    Comotti, Angiolina; Bracco, Silvia; Sozzani, Piero

    2016-09-20

    Molecules and materials can show dynamic structures in which the dominant mechanism is rotary motion. The single mobile elements are defined as "molecular rotors" and exhibit special properties (compared with their static counterparts), being able in perspective to greatly modulate the dielectric response and form the basis for molecular motors that are designed with the idea of making molecules perform a useful mechanical function. The construction of ordered rotary elements into a solid is a necessary feature for such design, because it enables the alignment of rotors and the fine-tuning of their steric and dipolar interactions. Crystal surfaces or bulk crystals are the most suitable to adapt rotors in 2D or 3D arrangements and engineer juxtaposition of the rotors in an ordered way. Nevertheless, it is only in recent times that materials showing porosity and remarkably low density have undergone tremendous development. The characteristics of large free volume combine well with the virtually unhindered motion of the molecular rotors built into their structure. Indeed, the molecular rotors are used as struts in porous covalent and supramolecular architectures, spanning both hybrid and fully organic materials. The modularity of the approach renders possible a variety of rotor geometrical arrangements in both robust frameworks stable up to 850 K and self-assembled molecular materials. A nanosecond (fast dynamics) motional regime can be achieved at temperatures lower than 240 K, enabling rotor arrays operating in the solid state even at low temperatures. Furthermore, in nanoporous materials, molecular rotors can interact with the diffusing chemical species, be they liquids, vapors, or gases. Through this chemical intervention, rotor speed can be modulated at will, enabling a new generation of rotor-containing materials sensitive to guests. In principle, an applied electric field can be the stimulus for chemical release from porous materials. The effort needed to

  11. Molecular Rotors Built in Porous Materials.

    PubMed

    Comotti, Angiolina; Bracco, Silvia; Sozzani, Piero

    2016-09-20

    Molecules and materials can show dynamic structures in which the dominant mechanism is rotary motion. The single mobile elements are defined as "molecular rotors" and exhibit special properties (compared with their static counterparts), being able in perspective to greatly modulate the dielectric response and form the basis for molecular motors that are designed with the idea of making molecules perform a useful mechanical function. The construction of ordered rotary elements into a solid is a necessary feature for such design, because it enables the alignment of rotors and the fine-tuning of their steric and dipolar interactions. Crystal surfaces or bulk crystals are the most suitable to adapt rotors in 2D or 3D arrangements and engineer juxtaposition of the rotors in an ordered way. Nevertheless, it is only in recent times that materials showing porosity and remarkably low density have undergone tremendous development. The characteristics of large free volume combine well with the virtually unhindered motion of the molecular rotors built into their structure. Indeed, the molecular rotors are used as struts in porous covalent and supramolecular architectures, spanning both hybrid and fully organic materials. The modularity of the approach renders possible a variety of rotor geometrical arrangements in both robust frameworks stable up to 850 K and self-assembled molecular materials. A nanosecond (fast dynamics) motional regime can be achieved at temperatures lower than 240 K, enabling rotor arrays operating in the solid state even at low temperatures. Furthermore, in nanoporous materials, molecular rotors can interact with the diffusing chemical species, be they liquids, vapors, or gases. Through this chemical intervention, rotor speed can be modulated at will, enabling a new generation of rotor-containing materials sensitive to guests. In principle, an applied electric field can be the stimulus for chemical release from porous materials. The effort needed to

  12. Advanced desiccant materials research

    SciTech Connect

    Czanderna, A.W.; Thomas, T.M.

    1986-05-01

    The long-range goal of this task is to understand the role of surface phenomena in desiccant cooling materials. The background information includes a brief introduction to desiccant cooling systems (DCS) and the role of the desiccant as a system component. The purpose, background, rationale, and long-term technical approach for studying advanced desiccant materials are then treated. Experimental methods for measuring water vapor sorption by desiccants are described, and the rationale is then given for choosing a quartz crystal microbalance (QCM) for measuring sorption isotherms, rates, and cyclic stability. Background information is given about the QCM, including the quartz crystal resonator itself, the support structure for the quartz crystal, and the advantages and limitations of a QCM. The apparatus assembled and placed into operation during CY 1985 is described. The functions of the principal components of the equipment, i.e., the QCM, vacuum system, pressure gauges, residual gas analyzer, constant temperature bath, and data acquisition system, are described as they relate to the water vapor sorption measurements now under way. The criteria for narrowing the potential candidates as advanced desiccant materials for the initial studies are given. Also given is a list of 20 principal candidate materials identified based on the criteria and data available in the literature.

  13. Determination of connectivity in porous materials.

    PubMed

    Caccianotti, L; Lucchelli, E; Ramello, S; Spanò, G

    2012-12-01

    A method of practical use was set up to determine the connectivity in a porous material, modelling the physical system as a lattice, whose coordination number is assumed to be an index of connectivity itself. This task was approached through the theory of percolation and input data were provided by two different experimental techniques, that is, adsorption/desorption of nitrogen and mercury porosimetry. The overall procedure is based on the calculation of probability f(P) of occupation of the porous channels and of probability F(P) of percolation. In the framework of the above--mentioned lattice model, the average coordination number Z is calculated through the best fitting of a universal curve to the values found for F(P) and f(P), adopting as fitting parameter the ratio L between the characteristic linear dimension of the whole lattice and the characteristic linear dimension of each of its cells. The procedure described was implemented through a numerical code and applied to three commercial alumina. A simple empirical relationship was found between Z and the percolation threshold, showing an excellent coefficient of statistical correlation. The three products proved different in connectivity, allowing subtle distinctions from each other, despite their hysteresis cycles in the adsorption/desorption process appeared quite similar from a qualitative standpoint. PMID:23447967

  14. Large Deformations of a Soft Porous Material

    NASA Astrophysics Data System (ADS)

    MacMinn, Christopher W.; Dufresne, Eric R.; Wettlaufer, John S.

    2016-04-01

    Compressing a porous material will decrease the volume of the pore space, driving fluid out. Similarly, injecting fluid into a porous material can expand the pore space, distorting the solid skeleton. This poromechanical coupling has applications ranging from cell and tissue mechanics to geomechanics and hydrogeology. The classical theory of linear poroelasticity captures this coupling by combining Darcy's law with Terzaghi's effective stress and linear elasticity in a linearized kinematic framework. Linear poroelasticity is a good model for very small deformations, but it becomes increasingly inappropriate for moderate to large deformations, which are common in the context of phenomena such as swelling and damage, and for soft materials such as gels and tissues. The well-known theory of large-deformation poroelasticity combines Darcy's law with Terzaghi's effective stress and nonlinear elasticity in a rigorous kinematic framework. This theory has been used extensively in biomechanics to model large elastic deformations in soft tissues and in geomechanics to model large elastoplastic deformations in soils. Here, we first provide an overview and discussion of this theory with an emphasis on the physics of poromechanical coupling. We present the large-deformation theory in an Eulerian framework to minimize the mathematical complexity, and we show how this nonlinear theory simplifies to linear poroelasticity under the assumption of small strain. We then compare the predictions of linear poroelasticity with those of large-deformation poroelasticity in the context of two uniaxial model problems: fluid outflow driven by an applied mechanical load (the consolidation problem) and compression driven by a steady fluid throughflow. We explore the steady and dynamical errors associated with the linear model in both situations, as well as the impact of introducing a deformation-dependent permeability. We show that the error in linear poroelasticity is due primarily to kinematic

  15. Siloxane treatment by adsorption into porous materials.

    PubMed

    Ricaurte Ortega, D; Subrenat, A

    2009-09-01

    Siloxanes are widely used in different applications: health care, dry cleaning, household products, paints and coatings, paper, personal care, for example. This explains their prevalence in the environment. Because of their volatile nature, most of the time they are dispersed in the atmosphere, but they can also be present in the slurry from landfills. During anaerobic digestion, when the temperature goes up to 60 degrees C, siloxanes are volatilized, forming part of the biogas. Operational problems using biogas to produce energy, heat and hydrogen have been identified. At high temperatures the siloxanes are transformed into silicate dioxide (commonly called sand transmission). These white deposits may adhere to metal or catalytic substrate surfaces, seriously reducing equipment efficiency, and this can be a reason for changing equipment warranties. Consequently, elimination of siloxanes has become very important. Unfortunately, relatively little information can be found on this subject. Nevertheless some authors have described different analytical methods for siloxane quantification, and recent studies have looked at the presence of siloxanes in landfills and the restriction on the energy recovery equipment using the biogas produced. The growing consumption of siloxanes and silicones in industrial processes consequently increase their prevalence in the environment, hampering the use of biogas as a source of 'green energy'. Therefore, the principal focus of this study is the treatment of siloxanes. Their elimination was carried out using an adsorption process with four different porous materials: activated carbon cloths (ACC), granular activated carbon (GAC), zeolite and silica gel. Two representative siloxane compounds were used in this study, hexamethyldisiloxane (L2) and octamethylcyclotetrasiloxane (D4). Adsorption kinetics and isotherms in batch reactors were performed. It was observed that the mass transfer into the porous material was more rapid for the

  16. SPUTTERING FROM A POROUS MATERIAL BY PENETRATING IONS

    SciTech Connect

    Rodriguez-Nieva, J. F.; Bringa, E. M.; Cassidy, T. A.; Caro, A.; Loeffler, M. J.; Farkas, D.

    2011-12-10

    Porous materials are ubiquitous in the universe and weathering of porous surfaces plays an important role in the evolution of planetary and interstellar materials. Sputtering of porous solids in particular can influence atmosphere formation, surface reflectivity, and the production of the ambient gas around materials in space. Several previous studies and models have shown a large reduction in the sputtering of a porous solid compared to the sputtering of the non-porous solid. Using molecular dynamics simulations we study the sputtering of a nanoporous solid with 55% of the solid density. We calculate the electronic sputtering induced by a fast, penetrating ion, using a thermal spike representation of the deposited energy. We find that sputtering for this porous solid is, surprisingly, the same as that for a full-density solid, even though the sticking coefficient is high.

  17. Sputtering from a Porous Material by Penetrating Ions

    NASA Astrophysics Data System (ADS)

    Rodriguez-Nieva, J. F.; Bringa, E. M.; Cassidy, T. A.; Johnson, R. E.; Caro, A.; Fama, M.; Loeffler, M. J.; Baragiola, R. A.; Farkas, D.

    2011-12-01

    Porous materials are ubiquitous in the universe and weathering of porous surfaces plays an important role in the evolution of planetary and interstellar materials. Sputtering of porous solids in particular can influence atmosphere formation, surface reflectivity, and the production of the ambient gas around materials in space. Several previous studies and models have shown a large reduction in the sputtering of a porous solid compared to the sputtering of the non-porous solid. Using molecular dynamics simulations we study the sputtering of a nanoporous solid with 55% of the solid density. We calculate the electronic sputtering induced by a fast, penetrating ion, using a thermal spike representation of the deposited energy. We find that sputtering for this porous solid is, surprisingly, the same as that for a full-density solid, even though the sticking coefficient is high.

  18. Sputtering from a Porous Material by Penetrating Ions

    NASA Technical Reports Server (NTRS)

    Rodriguez-Nieva, J. F.; Bringa, E. M.; Cassidy, T. A.; Johnson, R. E.; Caro, A.; Fama, M.; Loeffler, M.; Baragiola, R. A.; Farkas, D.

    2012-01-01

    Porous materials are ubiquitous in the universe and weathering of porous surfaces plays an important role in the evolution of planetary and interstellar materials. Sputtering of porous solids in particular can influence atmosphere formation, surface reflectivity, and the production of the ambient gas around materials in space, Several previous studies and models have shown a large reduction in the sputtering of a porous solid compared to the sputtering of the non-porous solid. Using molecular dynamics simulations we study the sputtering of a nanoporous solid with 55% of the solid density. We calculate the electronic sputtering induced by a fast, penetrating ion, using a thermal spike representation of the deposited energy. We find that sputtering for this porous solid is, surprisingly, the same as that for a full-density solid, even though the sticking coefficient is high.

  19. Accelerating advanced-materials commercialization

    NASA Astrophysics Data System (ADS)

    Maine, Elicia; Seegopaul, Purnesh

    2016-05-01

    Long commercialization times, high capital costs and sustained uncertainty deter investment in innovation for advanced materials. With appropriate strategies, technology and market uncertainties can be reduced, and the commercialization of advanced materials accelerated.

  20. Fabricating porous materials using interpenetrating inorganic-organic composite gels

    DOEpatents

    Seo, Dong-Kyun; Volosin, Alex

    2016-06-14

    Porous materials are fabricated using interpenetrating inorganic-organic composite gels. A mixture or precursor solution including an inorganic gel precursor, an organic polymer gel precursor, and a solvent is treated to form an inorganic wet gel including the organic polymer gel precursor and the solvent. The inorganic wet gel is then treated to form a composite wet gel including an organic polymer network in the body of the inorganic wet gel, producing an interpenetrating inorganic-organic composite gel. The composite wet gel is dried to form a composite material including the organic polymer network and an inorganic network component. The composite material can be treated further to form a porous composite material, a porous polymer or polymer composite, a porous metal oxide, and other porous materials.

  1. Dissolution of a surfactant-containing active porous material.

    PubMed

    Brielles, Nelly; Chantraine, Florence; Viana, Marylène; Chulia, Dominique; Branlard, Paul; Rubinstenn, Gilles; Lequeux, François; Mondain-Monval, Olivier

    2008-12-15

    We have studied the imbibition and dissolution of a porous material in two separate scenarios: (1) when the porous material contains a surfactant powder and (2) when the porous material is dissolved in a surfactant solution. We show that the dissolution kinetics in both scenarios is significantly affected by the presence of the surfactant and results in an increase in the characteristic imbibition time of the porous material, which can be well understood in the framework of the classical law of capillarity. Slowing of the imbibition kinetics was found to be affected by a modification of the liquid wetting properties, but is also affected by a variation in the solubility of the porous material in the presence of the surfactant. Furthermore, there is a depletion effect of the surfactant inside the rising liquid, which is in good agreement with previous work and theoretical predictions.

  2. Thermal conductivity and electrical resistivity of porous materials

    NASA Technical Reports Server (NTRS)

    Koh, J. C. Y.; Fortini, A.

    1972-01-01

    Process for determining thermal conductivity and electrical resistivity of porous materials is described. Characteristics of materials are identified and used in development of mathematical models. Limitations of method are examined.

  3. Porous silicon as a substrate material for potentiometric biosensors

    NASA Astrophysics Data System (ADS)

    Thust, Marion; Schöning, M. J.; Frohnhoff, S.; Arens-Fischer, R.; Kordos, P.; Lüth, H.

    1996-01-01

    For the first time porous silicon has been investigated for the purpose of application as a substrate material for potentiometric biosensors operating in aqueous solutions. Porous silicon was prepared from differently doped silicon substrates by a standard anodic etching process. After oxidation, penicillinase, an enzyme sensitive to penicillin, was bound to the porous structure by physical adsorption. To characterize the electrochemical properties of the so build up penicillin biosensor, capacitance - voltage (C - V) measurements were performed on these field-effect structures.

  4. Studies of acoustical properties of bulk porous flexible materials

    NASA Technical Reports Server (NTRS)

    Lambert, R. F.

    1984-01-01

    Acoustic prediction and measurement of bulk porous materials with flexible frames is investigated. The acoustic properties of Kevlar 29 are examined. Various acoustic tests are employed to determine impedance, sound wave propagation, and wave pressure equations for the highly porous fiber composites. The derivation of design equations and future research goals are included.

  5. Dynamic magnetic compaction of porous materials

    SciTech Connect

    1998-10-29

    IAP Research began development of the Dynamic Magnetic Compaction (DMC) process three years before the CRADA was established. IAP Research had experimentally demonstrated the feasibility of the process, and conducted a basic market survey. IAP identified and opened discussions with industrial partners and established the basic commercial cost structure. The purpose of this CRADA project was to predict and verify optimum pressure vs. time history for the compaction of porous copper and tungsten. LLNL modeled the rapid compaction of powdered material from an initial density of about 30% theoretical maximum to more than 90% theoretical maximum. The compaction simulations were benchmarked against existing data and new data was acquired by IAP Research. The modeling was used to perform parameter studies on the pressure loading time history, initial porosity and temperature. LLNL ran simulations using codes CALE or NITO and compared the simulations with published compaction data and equation of state (EOS) data. This project did not involve the development or modification of software code. CALE and NITO were existing software programs at LLNL. No modification of these programs occurred within the scope of the CRADA effort.

  6. METHOD OF IMPREGNATING A POROUS MATERIAL

    DOEpatents

    Steele, G.N.

    1960-06-01

    A method of impregnating a porous body with an inorganic uranium- containing salt is outlined and comprises dissolving a water-soluble uranium- containing salt in water; saturating the intercommunicating pores of the porous body with the salt solution; infusing ammonia gas into the intercommunicating pores of the body, the ammonia gas in water chemically reacting with the water- soluble uranium-containing salt in the water solvent to form a nonwater-soluble uranium-containing precipitant; and evaporating the volatile unprecipitated products from the intercommunicating pores whereby the uranium-containing precipitate is uniformly distributed in the intercommunicating peres of the porous body.

  7. Characterization of porous media and refractory materials

    NASA Astrophysics Data System (ADS)

    Chen, Xin

    Because of its unique advantages on energy savings and casting complex shapes, Lost Foam Casting (LFC) has been widely used as a replacement to the conventional techniques (sand and investment castings). In order to continuously improve the quality of the Lost Foam Casting process for reducing scrap rate and increasing energy savings, the US Department of Energy sponsored the present study to develop new characterization techniques for enhancing the understanding of the fundamental properties of the refractory materials used in the Lost Foam Casting process. In this study, new techniques are proposed to characterize the refractory materials' properties such as particle size, particle shape, rheological behavior, transport properties, microstructure, thickness, as well as packing properties. The microstructure information obtained from the proposed technique is found to be well correlated with the transport properties of the porous coating materials. A procedure using a three-dimensional computational fluid dynamics code is developed to simulate experimental gas flow data for solving complex boundary value problems. In this study, the effects of dilution and dispersion on the coating properties such as transport properties and microstructures are also investigated. Results show that the dilution and dispersion have opposing influences on the pore size and transport properties. In addition, this study also includes another part of the permeability system, the un-bonded granular materials used in the Lost Foam Casting process. A three-dimensional (3-D) computer program is developed to simulate the packing behavior of granular materials at a loose state using a "drop and roll" method. This study provides a systematic characterization of the LFC refractory coating slurries, dried refractory coating, and the granular media. This study also demonstrates the application of proposed characterization techniques for coating quality control using statistical process control

  8. Advanced composite materials and processes

    NASA Technical Reports Server (NTRS)

    Baucom, Robert M.

    1991-01-01

    Composites are generally defined as two or more individual materials, which, when combined into a single material system, results in improved physical and/or mechanical properties. The freedom of choice of the starting components for composites allows the generation of materials that can be specifically tailored to meet a variety of applications. Advanced composites are described as a combination of high strength fibers and high performance polymer matrix materials. These advanced materials are required to permit future aircraft and spacecraft to perform in extended environments. Advanced composite precursor materials, processes for conversion of these materials to structures, and selected applications for composites are reviewed.

  9. Synthesis and gas adsorption study of porous metal-organic framework materials

    NASA Astrophysics Data System (ADS)

    Mu, Bin

    Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) have become the focus of intense study over the past decade due to their potential for advancing a variety of applications including air purification, gas storage, adsorption separations, catalysis, gas sensing, drug delivery, and so on. These materials have some distinct advantages over traditional porous materials such as the well-defined structures, uniform pore sizes, chemically functionalized sorption sites, and potential for postsynthetic modification, etc. Thus, synthesis and adsorption studies of porous MOFs have increased substantially in recent years. Among various prospective applications, air purification is one of the most immediate concerns, which has urgent requirements to improve current nuclear, biological, and chemical (NBC) filters involving commercial and military purposes. Thus, the major goal of this funded project is to search, synthesize, and test these novel hybrid porous materials for adsorptive removal of toxic industrial chemicals (TICs) and chemical warfare agents (CWAs), and to install the benchmark for new-generation NBC filters. The objective of this study is three-fold: (i) Advance our understanding of coordination chemistry by synthesizing novel MOFs and characterizing these porous coordination polymers; (ii) Evaluate porous MOF materials for gasadsorption applications including CO2 capture, CH4 storage, other light gas adsorption and separations, and examine the chemical and physical properties of these solid adsorbents including thermal stability and heat capacity of MOFs; (iii) Evaluate porous MOF materials for next-generation NBC filter media by adsorption breakthrough measurements of TICs on MOFs, and advance our understanding about structureproperty relationships of these novel adsorbents.

  10. Applications of hierarchically structured porous materials from energy storage and conversion, catalysis, photocatalysis, adsorption, separation, and sensing to biomedicine.

    PubMed

    Sun, Ming-Hui; Huang, Shao-Zhuan; Chen, Li-Hua; Li, Yu; Yang, Xiao-Yu; Yuan, Zhong-Yong; Su, Bao-Lian

    2016-06-13

    Over the last decade, significant effort has been devoted to the applications of hierarchically structured porous materials owing to their outstanding properties such as high surface area, excellent accessibility to active sites, and enhanced mass transport and diffusion. The hierarchy of porosity, structural, morphological and component levels in these materials is key for their high performance in all kinds of applications. The introduction of hierarchical porosity into materials has led to a significant improvement in the performance of materials. Herein, recent progress in the applications of hierarchically structured porous materials from energy conversion and storage, catalysis, photocatalysis, adsorption, separation, and sensing to biomedicine is reviewed. Their potential future applications are also highlighted. We particularly dwell on the relationship between hierarchically porous structures and properties, with examples of each type of hierarchically structured porous material according to its chemical composition and physical characteristics. The present review aims to open up a new avenue to guide the readers to quickly obtain in-depth knowledge of applications of hierarchically porous materials and to have a good idea about selecting and designing suitable hierarchically porous materials for a specific application. In addition to focusing on the applications of hierarchically porous materials, this comprehensive review could stimulate researchers to synthesize new advanced hierarchically porous solids.

  11. Predicting Pressure Drop In Porous Materials

    NASA Technical Reports Server (NTRS)

    Lawing, Pierce L.

    1990-01-01

    Theory developed to predict drop in pressure based on drag of individual fibers. Simple correlation method for data also developed. Helps in predicting flow characteristics of many strain-isolation pad (SIP) glow geometries in Shuttle Orbiter tile system. Also helps in predicting venting characteristics of tile assemblies during ascent and leakage of hot gas under tiles during descent. Useful in study of mechanics of flows through fibrous and porous media, and procedures applicable to purged fiberglass insulation, dialysis filters, and other fibrous and porous media.

  12. TESTING ANTIMICROBIAL EFFICACY ON POROUS MATERIALS

    EPA Science Inventory

    The efficacy of antimicrobial treatments to eliminate or control biological growth in the indoor environment can easily be tested on nonporous surfaces. However, the testing of antimicrobial efficacy on porous surfaces, such as those found in the indoor environment [i.e., gypsum ...

  13. Hierarchically porous nitrogen-doped graphene-NiCo(2)O(4) hybrid paper as an advanced electrocatalytic water-splitting material.

    PubMed

    Chen, Sheng; Qiao, Shi-Zhang

    2013-11-26

    In this work, we report a three-dimensional (3D) oxygen evolution reaction (OER) catalyst with hierarchical pores for water splitting. The remarkable features of well-developed in- and out-of-plane pores, 3D conductive networks, and N-doping have greatly promoted the transport in electrodes and assured high catalytic efficiency. The 3D hybrid paper of N-doped graphene-NiCo2O4 has shown a remarkable OER catalytic activity that was comparable to that of previously reported noble metal catalysts (IrO2). The catalytic process occurred with favorable kinetics and strong durability. The dual-active-site mechanism is responsible for the excellent performance of the hybrid catalyst; that is, the edges of NiCo2O4 and the N (O)-metal (Ni or Co) bonds are both active sites. This study affords a new strategy to achieve optimal performance in 3D catalysts, which may be extended to the preparation of other 3D hybrid materials for a broad range of technological applications.

  14. Advanced Materials Technology

    NASA Technical Reports Server (NTRS)

    Blankenship, C. P. (Compiler); Teichman, L. A. (Compiler)

    1982-01-01

    Composites, polymer science, metallic materials (aluminum, titanium, and superalloys), materials processing technology, materials durability in the aerospace environment, ceramics, fatigue and fracture mechanics, tribology, and nondestructive evaluation (NDE) are discussed. Research and development activities are introduced to the nonaerospace industry. In order to provide a convenient means to help transfer aerospace technology to the commercial mainstream in a systematic manner.

  15. Advanced neutron absorber materials

    DOEpatents

    Branagan, Daniel J.; Smolik, Galen R.

    2000-01-01

    A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with enhanced resistance to corrosion, oxidation and leaching.

  16. Porous materials produced from incineration ash using thermal plasma technology.

    PubMed

    Yang, Sheng-Fu; Chiu, Wen-Tung; Wang, To-Mai; Chen, Ching-Ting; Tzeng, Chin-Ching

    2014-06-01

    This study presents a novel thermal plasma melting technique for neutralizing and recycling municipal solid waste incinerator (MSWI) ash residues. MSWI ash residues were converted into water-quenched vitrified slag using plasma vitrification, which is environmentally benign. Slag is adopted as a raw material in producing porous materials for architectural and decorative applications, eliminating the problem of its disposal. Porous materials are produced using water-quenched vitrified slag with Portland cement and foaming agent. The true density, bulk density, porosity and water absorption ratio of the foamed specimens are studied here by varying the size of the slag particles, the water-to-solid ratio, and the ratio of the weights of the core materials, including the water-quenched vitrified slag and cement. The thermal conductivity and flexural strength of porous panels are also determined. The experimental results show the bulk density and the porosity of the porous materials are 0.9-1.2 g cm(-3) and 50-60%, respectively, and the pore structure has a closed form. The thermal conductivity of the porous material is 0.1946 W m(-1) K(-1). Therefore, the slag composite materials are lightweight and thermal insulators having considerable potential for building applications.

  17. Excellent cycling stability and superior rate capability of a graphene-amorphous FePO4 porous nanowire hybrid as a cathode material for sodium ion batteries.

    PubMed

    Yang, Gaoliang; Ding, Bing; Wang, Jie; Nie, Ping; Dou, Hui; Zhang, Xiaogang

    2016-04-28

    A porous nanowire material consisting of graphene-amorphous FePO4 was investigated as an advanced cathode material for sodium ion batteries for large-scale applications. This hybrid cathode material showed excellent cycling performance and superior rate capability, which were attributed to the porous nanowire structure and the existence of graphene. PMID:27064740

  18. Excellent cycling stability and superior rate capability of a graphene-amorphous FePO4 porous nanowire hybrid as a cathode material for sodium ion batteries.

    PubMed

    Yang, Gaoliang; Ding, Bing; Wang, Jie; Nie, Ping; Dou, Hui; Zhang, Xiaogang

    2016-04-28

    A porous nanowire material consisting of graphene-amorphous FePO4 was investigated as an advanced cathode material for sodium ion batteries for large-scale applications. This hybrid cathode material showed excellent cycling performance and superior rate capability, which were attributed to the porous nanowire structure and the existence of graphene.

  19. Migration Mechanism for Atomic Hydrogen in Porous Carbon Materials

    SciTech Connect

    Narayanan, B.; Zhao, Y. F.; Ciobanu, C. V.

    2012-05-14

    To explain the fast kinetics of H in porous carbon, we propose that the migration relies on H hopping from a carbon nanotube (CNT) to another. Using density functional theory, we have found that the barrier for H hopping becomes smaller than that for diffusion along a tube for certain CNT separations, decreasting to less than 0.5 eV for separations of -3.1 {angstrom}. Such significant reduction occurs irrespective of radius, chirality, registry, and orientation of the two CNTs: the diffusion is thus facilitated by the porous nature of the material itself. The mechanism proposed is applicable for any porous carbon-based nanomaterials.

  20. Thermal conductivity and electrical resistivity of porous material

    NASA Technical Reports Server (NTRS)

    Koh, J. C. Y.; Fortini, A.

    1971-01-01

    Thermal conductivity and electrical resistivity of porous materials, including 304L stainless steel Rigimesh, 304L stainless steel sintered spherical powders, and OFHC sintered spherical powders at different porosities and temperatures are reported and correlated. It was found that the thermal conductivity and electrical resistivity can be related to the solid material properties and the porosity of the porous matrix regardless of the matrix structure. It was also found that the Wiedermann-Franz-Lorenz relationship is valid for the porous materials under consideration. For high conductivity materials, the Lorenz constant and the lattice component of conductivity depend on the material and are independent of the porosity. For low conductivity, the lattice component depends on the porosity as well.

  1. Filling Porous Microspheres With Magnetic Material

    NASA Technical Reports Server (NTRS)

    Chang, Manchium; Colvin, Michael S.

    1990-01-01

    New process produces magnetic microspheres with controllable sizes, compositions, and properties for use in medical diagnostic tests, biological research, and chemical processes. Paramagnetic microspheres also made with process. Porous plastic microspheres prepared by polymerization of monomer in diluent by cross-linking agent. When diluent removed, it leaves tiny pores throughout polymerized spheres. Size and distribution of pores determined by amount and type of diluent and cross-linking agent.

  2. Porous Carbon Supports: Recent Advances with Various Morphologies and Compositions

    DOE PAGES

    Zhang, Pengfei; Zhu, Huiyuan; Dai, Sheng

    2015-08-31

    The importance of porous carbon as the support material is well recognized in the catalysis community, and it would be even more attractive if several characteristics are considered, such as the stability in acidic and basic media or the ease of noble metal recovery through complete burn off. Because it is still difficult to obtain constant properties even from batch to batch, activated carbons are not popular in industrial catalysis now.

  3. Tissue engineering scaffold material of porous nanohydroxyapatite/polyamide 66.

    PubMed

    Xu, Qian; Lu, Hongyan; Zhang, Jingchao; Lu, Guoyu; Deng, Zhennan; Mo, Anchun

    2010-05-13

    The aim of the study was to investigate a porous nanohydroxyapatite/polyamide 66 (n-HA/PA66) scaffold material that was implanted into muscle and tibiae of 16 New Zealand white rabbits to evaluate the biocompatibility and osteogenesis and osteoinductivity of the materials in vivo. The samples were harvested at 2, 4, 12 and 26 weeks respectively, and subjected to histological analysis. At 2 weeks, the experiment showed that osteogenesis was detected in porous n-HA/PA66 composite and the density of new bone formation was similar to the surrounding host bone at 12 weeks. The study indicated that three-dimensional pore structures could facilitate cell adhesion, differentiation and proliferation, and help with fibrovascular and nerve colonization. In conclusion, porous n-HA/PA66 scaffold material could be a good candidate as a bone substitute material used in clinics due to its excellent histocompatibility, osteoconductivity and osteoinductivity.

  4. Advanced materials and the economy

    SciTech Connect

    Clark, J.P.; Flemings, M.C.

    1986-10-01

    Advances in materials science and engineering have impact quickly throughout the economy. On the average, every person in the US requires the securing and processing of some 20,000 pounds of nonrenewable, nonfuel mineral resources each year. Industries engaged in the direct production of primary materials employ approximately 1.5 million wage and salaried personnel, or about 1.5% of the labor force. On each person employed in the primary materials industries depend the jobs of from two to three workers in other sectors. The value of shipments of advanced materials is about $70 billion, or approximately 14% of total materials shipments. The production of such materials occupies about 10% of the total labor force of the materials industries. As in the case of employment, the indirect effect of the presence of these materials on the rest of the economy is highly significant. The reason is that advanced materials are not an end product; they are assembled into components critical to the successful performance and operation of such large, complex systems as aircraft and aerospace vehicles, electronic devices and automobiles. Advanced materials are essential to the future growth of these and other industries. In fact, progress in materials science sets ultimate limits on the rate at which key sectors of the economy can grown.

  5. Application of porous materials for laminar flow control

    NASA Technical Reports Server (NTRS)

    Pearce, W. E.

    1978-01-01

    Fairly smooth porous materials were elected for study Doweave; Fibermetal; Dynapore; and perforated titanium sheet. Factors examined include: surface smoothness; suction characteristics; porosity; surface impact resistance; and strain compatibility. A laminar flow control suction glove arrangement was identified with material combinations compatible with thermal expansion and structural strain.

  6. Advanced electron microscopy for advanced materials.

    PubMed

    Van Tendeloo, Gustaaf; Bals, Sara; Van Aert, Sandra; Verbeeck, Jo; Van Dyck, Dirk

    2012-11-01

    The idea of this Review is to introduce newly developed possibilities of advanced electron microscopy to the materials science community. Over the last decade, electron microscopy has evolved into a full analytical tool, able to provide atomic scale information on the position, nature, and even the valency atoms. This information is classically obtained in two dimensions (2D), but can now also be obtained in 3D. We show examples of applications in the field of nanoparticles and interfaces.

  7. Development of advanced thermoelectric materials

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The development of an advanced thermoelectric material for radioisotope thermoelectric generator (RTG) applications is reported. A number of materials were explored. The bulk of the effort, however, was devoted to improving silicon germanium alloys by the addition of gallium phosphide, the synthesis and evaluation of lanthanum chrome sulfide and the formulation of various mixtures of lanthanum sulfide and chrome sulfide. It is found that each of these materials exhibits promise as a thermoelectric material.

  8. Computer simulation of chemical reactions in porous materials

    NASA Astrophysics Data System (ADS)

    Turner, Christoffer Heath

    Understanding reactions in nanoporous materials from a purely experimental perspective is a difficult task. Measuring the chemical composition of a reacting system within a catalytic material is usually only accomplished through indirect methods, and it is usually impossible to distinguish between true chemical equilibrium and metastable states. In addition, measuring molecular orientation or distribution profiles within porous systems is not easily accomplished. However, molecular simulation techniques are well-suited to these challenges. With appropriate simulation techniques and realistic molecular models, it is possible to validate the dominant physical and chemical forces controlling nanoscale reactivity. Novel nanostructured catalysts and supports can be designed, optimized, and tested using high-performance computing and advanced modeling techniques in order to guide the search for next-generation catalysts---setting new targets for the materials synthesis community. We have simulated the conversion of several different equilibrium-limited reactions within microporous carbons and we find that the pore size, pore geometry, and surface chemistry are important factors for determining the reaction yield. The equilibrium-limited reactions that we have modeled include nitric oxide dimerization, ammonia synthesis, and the esterification of acetic acid, all of which show yield enhancements within microporous carbons. In conjunction with a yield enhancement of the esterification reaction, selective adsorption of ethyl acetate within carbon micropores demonstrates an efficient method for product recovery. Additionally, a new method has been developed for simulating reaction kinetics within porous materials and other heterogeneous environments. The validity of this technique is first demonstrated by reproducing the kinetics of hydrogen iodide decomposition in the gas phase, and then predictions are made within slit-shaped carbon pores and carbon nanotubes. The rate

  9. Methods for removing contaminant matter from a porous material

    DOEpatents

    Fox, Robert V [Idaho Falls, ID; Avci, Recep [Bozeman, MT; Groenewold, Gary S [Idaho Falls, ID

    2010-11-16

    Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

  10. Transient Infrared Measurement of Laser Absorption Properties of Porous Materials

    NASA Astrophysics Data System (ADS)

    Marynowicz, Andrzej

    2016-06-01

    The infrared thermography measurements of porous building materials have become more frequent in recent years. Many accompanying techniques for the thermal field generation have been developed, including one based on laser radiation. This work presents a simple optimization technique for estimation of the laser beam absorption for selected porous building materials, namely clinker brick and cement mortar. The transient temperature measurements were performed with the use of infrared camera during laser-induced heating-up of the samples' surfaces. As the results, the absorbed fractions of the incident laser beam together with its shape parameter are reported.

  11. Fatigue of advanced materials

    SciTech Connect

    Dauskardt, R.H.; Ritchie, R.O. . Center for Advanced Materials); Cox, B.N. )

    1993-08-01

    The development of toughened ceramics over the past 10 to 15 years is arguably one of the most important materials breakthroughs of this century. Monolithic and composite ceramic materials having fracture toughnesses up to an order of magnitude higher than those available 20 years ago have been produced using technologies based on scientific understanding and micromechanical models for in situ phase transformation, fiber bridging, ductile-particle toughening, and other toughening mechanisms. The irony of this, however, is that although ceramics can now be seriously considered for many structural applications, they can also, contrary to popular belief, be susceptible to degradation under cyclic fatigue loading. This is true even when the loading is fully compressive. As a result, a great deal of attention is now being paid to ceramic fatigue, largely because of the importance of cyclic loading in many of the potential applications for ceramics, such as gas-turbine and reciprocating engines. However, because the field is in its infancy, only limited fatigue property data have been documented, understanding of salient fatigue mechanisms has not been achieved, and the design of ceramic microstructures for optimum fatigue resistance has yet to be attempted.

  12. Advanced Aerospace Materials by Design

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Djomehri, Jahed; Wei, Chen-Yu

    2004-01-01

    The advances in the emerging field of nanophase thermal and structural composite materials; materials with embedded sensors and actuators for morphing structures; light-weight composite materials for energy and power storage; and large surface area materials for in-situ resource generation and waste recycling, are expected to :revolutionize the capabilities of virtually every system comprising of future robotic and :human moon and mars exploration missions. A high-performance multiscale simulation platform, including the computational capabilities and resources of Columbia - the new supercomputer, is being developed to discover, validate, and prototype next generation (of such advanced materials. This exhibit will describe the porting and scaling of multiscale 'physics based core computer simulation codes for discovering and designing carbon nanotube-polymer composite materials for light-weight load bearing structural and 'thermal protection applications.

  13. Gas sensing using porous materials for automotive applications.

    PubMed

    Wales, Dominic J; Grand, Julien; Ting, Valeska P; Burke, Richard D; Edler, Karen J; Bowen, Chris R; Mintova, Svetlana; Burrows, Andrew D

    2015-07-01

    Improvements in the efficiency of combustion within a vehicle can lead to reductions in the emission of harmful pollutants and increased fuel efficiency. Gas sensors have a role to play in this process, since they can provide real time feedback to vehicular fuel and emissions management systems as well as reducing the discrepancy between emissions observed in factory tests and 'real world' scenarios. In this review we survey the current state-of-the-art in using porous materials for sensing the gases relevant to automotive emissions. Two broad classes of porous material - zeolites and metal-organic frameworks (MOFs) - are introduced, and their potential for gas sensing is discussed. The adsorptive, spectroscopic and electronic techniques for sensing gases using porous materials are summarised. Examples of the use of zeolites and MOFs in the sensing of water vapour, oxygen, NOx, carbon monoxide and carbon dioxide, hydrocarbons and volatile organic compounds, ammonia, hydrogen sulfide, sulfur dioxide and hydrogen are then detailed. Both types of porous material (zeolites and MOFs) reveal great promise for the fabrication of sensors for exhaust gases and vapours due to high selectivity and sensitivity. The size and shape selectivity of the zeolite and MOF materials are controlled by variation of pore dimensions, chemical composition (hydrophilicity/hydrophobicity), crystal size and orientation, thus enabling detection and differentiation between different gases and vapours. PMID:25982991

  14. Gas sensing using porous materials for automotive applications.

    PubMed

    Wales, Dominic J; Grand, Julien; Ting, Valeska P; Burke, Richard D; Edler, Karen J; Bowen, Chris R; Mintova, Svetlana; Burrows, Andrew D

    2015-07-01

    Improvements in the efficiency of combustion within a vehicle can lead to reductions in the emission of harmful pollutants and increased fuel efficiency. Gas sensors have a role to play in this process, since they can provide real time feedback to vehicular fuel and emissions management systems as well as reducing the discrepancy between emissions observed in factory tests and 'real world' scenarios. In this review we survey the current state-of-the-art in using porous materials for sensing the gases relevant to automotive emissions. Two broad classes of porous material - zeolites and metal-organic frameworks (MOFs) - are introduced, and their potential for gas sensing is discussed. The adsorptive, spectroscopic and electronic techniques for sensing gases using porous materials are summarised. Examples of the use of zeolites and MOFs in the sensing of water vapour, oxygen, NOx, carbon monoxide and carbon dioxide, hydrocarbons and volatile organic compounds, ammonia, hydrogen sulfide, sulfur dioxide and hydrogen are then detailed. Both types of porous material (zeolites and MOFs) reveal great promise for the fabrication of sensors for exhaust gases and vapours due to high selectivity and sensitivity. The size and shape selectivity of the zeolite and MOF materials are controlled by variation of pore dimensions, chemical composition (hydrophilicity/hydrophobicity), crystal size and orientation, thus enabling detection and differentiation between different gases and vapours.

  15. Future requirements for advanced materials

    NASA Technical Reports Server (NTRS)

    Olstad, W. B.

    1980-01-01

    Recent advances and future trends in aerospace materials technology are reviewed with reference to metal alloys, high-temperature composites and adhesives, tungsten fiber-reinforced superalloys, hybrid materials, ceramics, new ablative materials, such as carbon-carbon composite and silica tiles used in the Shuttle Orbiter. The technologies of powder metallurgy coupled with hot isostatic pressing, near net forging, complex large shape casting, chopped fiber molding, superplastic forming, and computer-aided design and manufacture are emphasized.

  16. The Uniaxial Tensile Response of Porous and Microcracked Ceramic Materials

    SciTech Connect

    Pandey, Amit; Shyam, Amit; Watkins, Thomas R; Lara-Curzio, Edgar; Lara-Curzio, Edgar; Stafford, Randall; Hemker, Kevin J

    2014-01-01

    The uniaxial tensile stress-strain behavior of three porous ceramic materials was determined at ambient conditions. Test specimens in the form of thin beams were obtained from the walls of diesel particulate filter honeycombs and tested using a microtesting system. A digital image correlation technique was used to obtain full-field 2D in-plane surface displacement maps during tensile loading, and in turn, the 2D strains obtained from displacement fields were used to determine the Secant modulus, Young s modulus and initial Poisson s ratio of the three porous ceramic materials. Successive unloading-reloading experiments were performed at different levels of stress to decouple the linear elastic, anelastic and inelastic response in these materials. It was found that the stress-strain response of these materials was non-linear and that the degree of nonlinearity is related to the initial microcrack density and evolution of damage in the material.

  17. Methyl alcohol used as penetrant inspection medium for porous materials

    NASA Technical Reports Server (NTRS)

    Hendron, J. A.

    1971-01-01

    Porous material thoroughly wetted with alcohol shows persistent wet line or area at locations of cracks or porosity. Inspection is qualitative and repeatable, but is used quantitatively with select samples to grade density variations in graphite blocks. Photography is employed to achieve permanent record of results.

  18. Advanced materials for energy storage.

    PubMed

    Liu, Chang; Li, Feng; Ma, Lai-Peng; Cheng, Hui-Ming

    2010-02-23

    Popularization of portable electronics and electric vehicles worldwide stimulates the development of energy storage devices, such as batteries and supercapacitors, toward higher power density and energy density, which significantly depends upon the advancement of new materials used in these devices. Moreover, energy storage materials play a key role in efficient, clean, and versatile use of energy, and are crucial for the exploitation of renewable energy. Therefore, energy storage materials cover a wide range of materials and have been receiving intensive attention from research and development to industrialization. In this Review, firstly a general introduction is given to several typical energy storage systems, including thermal, mechanical, electromagnetic, hydrogen, and electrochemical energy storage. Then the current status of high-performance hydrogen storage materials for on-board applications and electrochemical energy storage materials for lithium-ion batteries and supercapacitors is introduced in detail. The strategies for developing these advanced energy storage materials, including nanostructuring, nano-/microcombination, hybridization, pore-structure control, configuration design, surface modification, and composition optimization, are discussed. Finally, the future trends and prospects in the development of advanced energy storage materials are highlighted.

  19. Characterizing He II flow through porous materials using counterflow data

    NASA Technical Reports Server (NTRS)

    Maddocks, J. R.; Van Sciver, S. W.

    1991-01-01

    An empirical extension of the two-fluid model is used to characterize He II flow through porous materials. It is shown that four empirical parameters are necessary to describe the pressure and temperature differences induced by He II flow through a porous sample. The three parameters required to determine pressure differences are measured in counterflow and found to compare favorably with those for isothermal flow. The fourth parameter, the Gorter-Mellink constant, differs substantially from smooth tube values. It is concluded that parameter values determined from counterflow can be used to predict pressure and temperature differences in a variety of flows to an accuracy of about +/- 20 percent.

  20. Wormhole growth in soluble porous materials

    SciTech Connect

    Nilson, R.H.; Griffiths, S.K. )

    1990-09-24

    Analytical solutions are derived for the quasisteady shape and speed of a single wormhole resulting from the coupled processes of Darcian fluid motion and chemical dissolution in a soluble permeable material. For an initially unsaturated medium, two-dimensional solutions are obtained by addressing an inverted free-boundary problem in which the spatial coordinates are treated as dependent variables on the plane of a complex potential. For initially saturated materials, solutions are obtained by analogy to Ivantsov's problem of dendrite growth.

  1. Hydrophobic Porous Material Adsorbs Small Organic Molecules

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K.; Hickey, Gregory S.

    1994-01-01

    Composite molecular-sieve material has pore structure designed specifically for preferential adsorption of organic molecules for sizes ranging from 3 to 6 angstrom. Design based on principle that contaminant molecules become strongly bound to surface of adsorbent when size of contaminant molecules is nearly same as that of pores in adsorbent. Material used to remove small organic contaminant molecules from vacuum systems or from enclosed gaseous environments like closed-loop life-support systems.

  2. Novel polymeric nanocomposites and porous materials prepared using organogels

    NASA Astrophysics Data System (ADS)

    Lai, Wei-Chi; Tseng, Shen-Chen

    2009-11-01

    We propose a new method for preparing polymeric nanocomposites and porous materials using self-assembled templates formed by 1,3:2,4-dibenzylidene sorbitol (DBS) organogels. DBS is capable of self-assembling into a 3D nanofibrillar network at relatively low concentrations in some organic solvents to produce organogels. In this study, we induced the formation of such physical cross-linked networks in styrene. Subsequently, we polymerized the styrene in the presence of chemical cross-linkers, divinyl benzene (DVB), with different amounts of DBS using thermal-initiated polymerization. The resulting materials were transparent, homogeneous polystyrene (PS) nanocomposites with both physical and chemical cross-links. The porous polymeric materials were obtained by solvent extraction of the DBS nanofibrils from the PS. Brunauer-Emmett-Teller (BET) measurements show that the amounts of DBS and DVB influenced the specific surface area after the removal of the DBS fibrils.

  3. Urothermal Synthesis of Crystalline Porous Materials

    PubMed Central

    Zhang, Jian; Bu, Julia T.; Chen, Shumei; Wu, Tao; Zheng, Shoutian; Chen, Yigang; Nieto, Ruben A.; Feng, Pingyun

    2015-01-01

    Pores from Urea Urea derivatives are shown here to be a highly verstaile solvent system for the synthesis of crystalline solids. In particular, reversible binding of urea derivatives to framework metal sites has been utilized to create a variety of materials integrating both porosity and open-metal sites. PMID:20954225

  4. Porous silicon based anode material formed using metal reduction

    SciTech Connect

    Anguchamy, Yogesh Kumar; Masarapu, Charan; Deng, Haixia; Han, Yongbong; Venkatachalam, Subramanian; Kumar, Sujeet; Lopez, Herman A.

    2015-09-22

    A porous silicon based material comprising porous crystalline elemental silicon formed by reducing silicon dioxide with a reducing metal in a heating process followed by acid etching is used to construct negative electrode used in lithium ion batteries. Gradual temperature heating ramp(s) with optional temperature steps can be used to perform the heating process. The porous silicon formed has a high surface area from about 10 m.sup.2/g to about 200 m.sup.2/g and is substantially free of carbon. The negative electrode formed can have a discharge specific capacity of at least 1800 mAh/g at rate of C/3 discharged from 1.5V to 0.005V against lithium with in some embodiments loading levels ranging from about 1.4 mg/cm.sup.2 to about 3.5 mg/cm.sup.2. In some embodiments, the porous silicon can be coated with a carbon coating or blended with carbon nanofibers or other conductive carbon material.

  5. Roughening of porous SiCOH materials in fluorocarbon plasmas

    NASA Astrophysics Data System (ADS)

    Bailly, F.; David, T.; Chevolleau, T.; Darnon, M.; Posseme, N.; Bouyssou, R.; Ducote, J.; Joubert, O.; Cardinaud, C.

    2010-07-01

    Porous SiCOH materials integration for integrated circuits faces serious challenges such as roughening during the etch process. In this study, atomic force microscopy is used to investigate the kinetics of SiCOH materials roughening when they are etched in fluorocarbon plasmas. We show that the root mean square roughness and the correlation length linearly increase with the etched depth, after an initiation period. We propose that: (1) during the first few seconds of the etch process, the surface of porous SiCOH materials gets denser. (2) Cracks are formed, leading to the formation of deep and narrow pits. (3) Plasma radicals diffuse through those pits and the pore network and modify the porous material at the bottom of the pits. (4) The difference in material density and composition between the surface and the bottom of the pits leads to a difference in etch rate and an amplification of the roughness. In addition to this intrinsic roughening mechanism, the presence of a metallic mask (titanium nitride) can lead to an extrinsic roughening mechanism, such as micromasking caused by metallic particles originating form the titanium nitride mask.

  6. Characterisation of porous materials for bioseparation.

    PubMed

    Barrande, M; Beurroies, I; Denoyel, R; Tatárová, I; Gramblicka, M; Polakovic, M; Joehnck, M; Schulte, M

    2009-10-01

    A set of chromatographic materials for bioseparation were characterised by various methods. Both commercial materials and new supports presenting various levels of rigidity were analysed. The methods included size-exclusion and capillary phenomena based techniques. Both batch exclusion and inverse size-exclusion chromatography were used. Gas adsorption, mercury porosimetry and thermoporometry were applied as well as a new method based on water desorption starting from the saturated state. When the rigidity of adsorbents is high enough, the agreement is reasonable between the values of the structural parameters that were determined (surface area, porosity, and pore size) by various methods. Nevertheless, a part of macroporosity may not be evidenced by inverse size-exclusion chromatography whereas it is visible by batch exclusion and the other methods. When the rigidity decreases, for example with soft swelling gels, where standard nitrogen adsorption or mercury porosimetry are no more reliable, two main situations are encountered: either the methods based on capillary phenomena (thermoporometry or water desorption) overestimate the pore size with an amplitude that depends on the method, or in some cases it is possible to distinguish water involved in the swelling of pore walls from that involved in pore filling by capillary condensation. PMID:19740472

  7. Characterisation of porous materials for bioseparation.

    PubMed

    Barrande, M; Beurroies, I; Denoyel, R; Tatárová, I; Gramblicka, M; Polakovic, M; Joehnck, M; Schulte, M

    2009-10-01

    A set of chromatographic materials for bioseparation were characterised by various methods. Both commercial materials and new supports presenting various levels of rigidity were analysed. The methods included size-exclusion and capillary phenomena based techniques. Both batch exclusion and inverse size-exclusion chromatography were used. Gas adsorption, mercury porosimetry and thermoporometry were applied as well as a new method based on water desorption starting from the saturated state. When the rigidity of adsorbents is high enough, the agreement is reasonable between the values of the structural parameters that were determined (surface area, porosity, and pore size) by various methods. Nevertheless, a part of macroporosity may not be evidenced by inverse size-exclusion chromatography whereas it is visible by batch exclusion and the other methods. When the rigidity decreases, for example with soft swelling gels, where standard nitrogen adsorption or mercury porosimetry are no more reliable, two main situations are encountered: either the methods based on capillary phenomena (thermoporometry or water desorption) overestimate the pore size with an amplitude that depends on the method, or in some cases it is possible to distinguish water involved in the swelling of pore walls from that involved in pore filling by capillary condensation.

  8. A hexangular ring-core NiCo2O4 porous nanosheet/NiO nanoparticle composite as an advanced anode material for LIBs and catalyst for CO oxidation applications.

    PubMed

    He, Yanyan; Xu, Liqiang; Zhai, Yanjun; Li, Aihua; Chen, Xiaoxia

    2015-10-11

    A porous hexangular ring-core NiCo2O4 nanosheet/NiO nanoparticle composite has been synthesized using a hydrothermal method followed by an annealing process in air. The as-obtained composite as an anode material exhibits a high initial discharge capacity of 1920.6 mA h g(-1) at a current density of 100 mA g(-1) and the capacity is retained at 1567.3 mA h g(-1) after 50 cycles. When it is utilized as a catalyst for CO oxidation, complete CO conversion is achieved at 115 °C and a catalytic life test demonstrates the good stability of the composite.

  9. Drying of porous materials in a medium with variable potentials

    SciTech Connect

    Liu, J.Y. )

    1991-08-01

    This paper presents an application of the Luikov system of heat and mass transfer equations in dimensionless form to predict the temperature and moisture distributions in a slab of capillary-porous material during drying. The heat and mass potentials of the external medium in the boundary conditions are assumed to vary linearly with time. The method of solution is illustrated by considering the drying of a slab of lumber. Numerical results based on the estimated thermophysical properties of spruce are presented.

  10. Excellent cycling stability and superior rate capability of a graphene-amorphous FePO4 porous nanowire hybrid as a cathode material for sodium ion batteries

    NASA Astrophysics Data System (ADS)

    Yang, Gaoliang; Ding, Bing; Wang, Jie; Nie, Ping; Dou, Hui; Zhang, Xiaogang

    2016-04-01

    A porous nanowire material consisting of graphene-amorphous FePO4 was investigated as an advanced cathode material for sodium ion batteries for large-scale applications. This hybrid cathode material showed excellent cycling performance and superior rate capability, which were attributed to the porous nanowire structure and the existence of graphene.A porous nanowire material consisting of graphene-amorphous FePO4 was investigated as an advanced cathode material for sodium ion batteries for large-scale applications. This hybrid cathode material showed excellent cycling performance and superior rate capability, which were attributed to the porous nanowire structure and the existence of graphene. Electronic supplementary information (ESI) available: Experimental section; SEM images, BET, XPS spectrum, TG curve and EIS spectra of the samples; the comparison of electrochemical performance with the reported results. See DOI: 10.1039/c6nr00409a

  11. Plasma Processing of Advanced Materials

    SciTech Connect

    Heberlein, Joachim, V.R.; Pfender, Emil; Kortshagen, Uwe

    2005-02-28

    Plasma Processing of Advanced Materials The project had the overall objective of improving our understanding of the influences of process parameters on the properties of advanced superhard materials. The focus was on high rate deposition processes using thermal plasmas and atmospheric pressure glow discharges, and the emphasis on superhard materials was chosen because of the potential impact of such materials on industrial energy use and on the environment. In addition, the development of suitable diagnostic techniques was pursued. The project was divided into four tasks: (1) Deposition of superhard boron containing films using a supersonic plasma jet reactor (SPJR), and the characterization of the deposition process. (2) Deposition of superhard nanocomposite films in the silicon-nitrogen-carbon system using the triple torch plasma reactor (TTPR), and the characterization of the deposition process. (3) Deposition of films consisting of carbon nanotubes using an atmospheric pressure glow discharge reactor. (4) Adapting the Thomson scattering method for characterization of atmospheric pressure non-uniform plasmas with steep spatial gradients and temporal fluctuations. This report summarizes the results.

  12. Simplified modeling of transition to detonation in porous energetic materials

    NASA Astrophysics Data System (ADS)

    Stewart, D. Scott; Asay, Blaine W.; Prasad, Kuldeep

    1994-07-01

    A simplified model that can predict the transitions from compaction to detonation and shock to detonation is given with the aim of describing experiments in beds of porous HMX. In the case of compaction to detonation, the energy of early impact generates a slowly moving, convective-reactive deflagration that expands near the piston face and evolves in a manner that is characteristic of confined deflagration to detonation transition. A single-phase state variable theory is adopted in contrast to a two-phase axiomatic mixture theory. The ability of the porous material to compact is treated as an endothermic process. Reaction is treated as an exothermic process. The algebraic (Rankine-Hugoniot) steady wave analysis is given for inert compaction waves and steady detonation waves in a piston supported configuration, typical of the experiments carried out in porous HMX. A structure analysis of the steady compaction wave is given. Numerical simulations of deflagration to detonation are carried out for parameters that describe an HMX-like material and compared with the experiments. The simple model predicts the high density plug that is observed in the experiments and suggests that the leading front of the plug is a secondary compaction wave. A shock to detonation transition is also numerically simulated.

  13. Simplified modeling of transition to detonation in porous energetic materials

    SciTech Connect

    Stewart, D.S. ); Asay, B.W. ); Prasad, K. )

    1994-07-01

    A simplified model that can predict the transitions from compaction to detonation and shock to detonation is given with the aim of describing experiments in beds of porous HMX. In the case of compaction to detonation, the energy of early impact generates a slowly moving, convective-reactive deflagration that expands near the piston face and evolves in a manner that is characteristic of confined deflagration to detonation transition. A single-phase state variable theory is adopted in contrast to a two-phase axiomatic mixture theory. The ability of the porous material to compact is treated as an endothermic process. Reaction is treated as an exothermic process. The algebraic (Rankine--Hugoniot) steady wave analysis is given for inert compaction waves and steady detonation waves in a piston supported configuration, typical of the experiments carried out in porous HMX. A structure analysis of the steady compaction wave is given. Numerical simulations of deflagration to detonation are carried out for parameters that describe an HMX-like material and compared with the experiments. The simple model predicts the high density plug that is observed in the experiments and suggests that the leading front of the plug is a secondary compaction wave. A shock to detonation transition is also numerically simulated.

  14. Acoustics of porous materials with partially opened porosity.

    PubMed

    Leclaire, P; Dupont, T; Panneton, R

    2013-12-01

    A theoretical and experimental study of the acoustic properties of porous materials containing dead-end (or partially opened) porosity was recently proposed by Dupont, Leclaire, Sicot, Gong, and Panneton [J. Appl. Phys. 110, 094903 (2011)]. The present article provides a description of partially opened porosity systems and their numerous potential applications in the general context of the study of porous materials, the classical models describing them, and the characterization techniques. It is shown that the dead-end pore effect can be treated independently and that the description of this effect can be associated with any acoustic model of porous media. Different theoretical developments describing the dead-end porosity effect are proposed. In particular, a model involving the average effective length of the dead-end pores is presented. It is also shown that if the dead-end effect can be treated separately, the transfer matrix method is particularly well suited for the description of single or multilayer systems with dead-end porosity.

  15. Fundamental problems in porous materials: Experiments & computer simulation

    NASA Astrophysics Data System (ADS)

    Xu, Zhanping

    Porous materials have attracted massive scientific and technological interest because of their extremely high surface-to-volume ratio, molecular tunability in construction, and surface-based applications. Through my PhD work, porous materials were engineered to meet the design in selective binding, self-healing, and energy damping. For example, crystalline MOFs with pore size spanning from a few angstroms to a couple of nanometers were chemically engineered to show 120 times more efficiency in binding of large molecules. In addition, we found building blocks released from those crystals can be further patched back through a healing process at ambient and low temperatures down to -56 °C. When building blocks are replaced with graphenes, ultra-flyweight aerogels with pore size larger than 100 nm were made to delay shock waves. More stable rigid porous metal with larger pores (~um) was also fabricated, and its performance and survivability are under investigation. Aside from experimental studies, we also successfully applied numerical simulations to study the mutual interaction between the nonplanar liquid-solid interface and colloidal particles during the freezing of the colloidal suspensions. Colloidal particles can be either rejected or engulfed by the evolving interface depending on the freezing speed and strength of interface-particle interaction. Our interactive simulation was achieved by programming both simulation module and visualization module on high performance GPU devices.

  16. Propagation of Terahertz Radiation in Porous Polymer and Ceramic Materials

    NASA Astrophysics Data System (ADS)

    Dodson, Caroline; Spicer, James; Fitch, Michael; Schuster, Paul; Osiander, Robert

    2005-04-01

    In this work we investigate the propagation of terahertz radiation through polyurethane foam and porous alumina ceramics to understand the effects of structure on the optical properties of these materials at terahertz frequencies. A terahertz time domain system with a GaAs photoconductive emitter and a ZnTe electro-optic crystal was used to generate and detect the transmitted terahertz signal. Using the amplitude and phase characteristics of these signals, the thickness, index of refraction, and other physical and optical properties of the materials were determined.

  17. Method of preparing thin porous sheets of ceramic material

    DOEpatents

    Swarr, Thomas E.; Nickols, Richard C.; Krasij, Myron

    1987-03-24

    A method of forming thin porous sheets of ceramic material for use as electrodes or other components in a molten carbonate fuel cell is disclosed. The method involves spray drying a slurry of fine ceramic particles in liquid carrier to produce generally spherical agglomerates of high porosity and a rough surface texture. The ceramic particles may include the electrode catalyst and the agglomerates can be calcined to improve mechanical strength. After slurrying with suitable volatile material and binder tape casting is used to form sheets that are sufficiently strong for further processing and handling in the assembly of a high temperature fuel cell.

  18. Method of preparing thin porous sheets of ceramic material

    DOEpatents

    Swarr, T.E.; Nickols, R.C.; Krasij, M.

    1984-05-23

    A method of forming thin porous sheets of ceramic material for use as electrodes or other components in a molten carbonate fuel cell is disclosed. The method involves spray drying a slurry of fine ceramic particles in liquid carrier to produce generally spherical agglomerates of high porosity and a rough surface texture. The ceramic particles may include the electrode catalyst and the agglomerates can be calcined to improve mechanical strength. After slurrying with suitable volatile material and binder tape casting is used to form sheets that are sufficiently strong for further processing and handling in the assembly of a high temperature fuel cell.

  19. Ceramic porous material and method of making same

    SciTech Connect

    Liu, Jun; Kim, Anthony Y.; Virden, Jud W.

    1997-01-01

    The invention is a mesoporous ceramic membrane having substantially uniform pore size. Additionally, the invention includes aqueous and non-aqueous processing routes to making the mesoporous ceramic membranes. According to one aspect of the present invention, inserting a substrate into a reaction chamber at pressure results in reaction products collecting on the substrate and forming a membrane thereon. According to another aspect of the present invention, a second aqueous solution that is sufficiently immiscible in the aqueous solution provides an interface between the two solutions whereon the mesoporous membrane is formed. According to a further aspect of the present invention, a porous substrate is placed at the interface between the two solutions permitting formation of a membrane on the surface or within the pores of the porous substrate. According to yet another aspect of the present invention, mesoporous ceramic materials are formed using a non-aqueous solvent and water-sensitive precursors.

  20. Ceramic porous material and method of making same

    DOEpatents

    Liu, J.; Kim, A.Y.; Virden, J.W.

    1997-07-08

    The invention is a mesoporous ceramic membrane having substantially uniform pore size. Additionally, the invention includes aqueous and non-aqueous processing routes to making the mesoporous ceramic membranes. According to one aspect of the present invention, inserting a substrate into a reaction chamber at pressure results in reaction products collecting on the substrate and forming a membrane thereon. According to another aspect of the present invention, a second aqueous solution that is sufficiently immiscible in the aqueous solution provides an interface between the two solutions whereon the mesoporous membrane is formed. According to a further aspect of the present invention, a porous substrate is placed at the interface between the two solutions permitting formation of a membrane on the surface or within the pores of the porous substrate. According to yet another aspect of the present invention, mesoporous ceramic materials are formed using a non-aqueous solvent and water-sensitive precursors. 21 figs.

  1. Supported metal nanoparticles on porous materials. Methods and applications.

    PubMed

    White, Robin J; Luque, Rafael; Budarin, Vitaliy L; Clark, James H; Macquarrie, Duncan J

    2009-02-01

    Nanoparticles are regarded as a major step forward to achieving the miniaturisation and nanoscaling effects and properties that have been utilised by nature for millions of years. The chemist is no longer observing and describing the behaviour of matter but is now able to manipulate and produce new types of materials with specific desired physicochemical characteristics. Such materials are receiving extensive attention across a broad range of research disciplines. The fusion between nanoparticle and nanoporous materials technology represents one of the most interesting of these rapidly expanding areas. The harnessing of nanoscale activity and selectivity, potentially provides extremely efficient catalytic materials for the production of commodity chemicals, and energy needed for a future sustainable society. In this tutorial review, we present an introduction to the field of supported metal nanoparticles (SMNPs) on porous materials, focusing on their preparation and applications in different areas. PMID:19169462

  2. Porous materials for thermal management under extreme conditions.

    PubMed

    Clyne, T W; Golosnoy, I O; Tan, J C; Markaki, A E

    2006-01-15

    A brief analysis is presented of how heat transfer takes place in porous materials of various types. The emphasis is on materials able to withstand extremes of temperature, gas pressure, irradiation, etc. i.e. metals and ceramics, rather than polymers. A primary aim is commonly to maximize either the thermal resistance (i.e. provide insulation) or the rate of thermal equilibration between the material and a fluid passing through it (i.e. to facilitate heat exchange). The main structural characteristics concern porosity (void content), anisotropy, pore connectivity and scale. The effect of scale is complex, since the permeability decreases as the structure is refined, but the interfacial area for fluid-solid heat exchange is, thereby, raised. The durability of the pore structure may also be an issue, with a possible disadvantage of finer scale structures being poor microstructural stability under service conditions. Finally, good mechanical properties may be required, since the development of thermal gradients, high fluid fluxes, etc. can generate substantial levels of stress. There are, thus, some complex interplays between service conditions, pore architecture/scale, fluid permeation characteristics, convective heat flow, thermal conduction and radiative heat transfer. Such interplays are illustrated with reference to three examples: (i) a thermal barrier coating in a gas turbine engine; (ii) a Space Shuttle tile; and (iii) a Stirling engine heat exchanger. Highly porous, permeable materials are often made by bonding fibres together into a network structure and much of the analysis presented here is oriented towards such materials. PMID:18272456

  3. Porous materials for thermal management under extreme conditions.

    PubMed

    Clyne, T W; Golosnoy, I O; Tan, J C; Markaki, A E

    2006-01-15

    A brief analysis is presented of how heat transfer takes place in porous materials of various types. The emphasis is on materials able to withstand extremes of temperature, gas pressure, irradiation, etc. i.e. metals and ceramics, rather than polymers. A primary aim is commonly to maximize either the thermal resistance (i.e. provide insulation) or the rate of thermal equilibration between the material and a fluid passing through it (i.e. to facilitate heat exchange). The main structural characteristics concern porosity (void content), anisotropy, pore connectivity and scale. The effect of scale is complex, since the permeability decreases as the structure is refined, but the interfacial area for fluid-solid heat exchange is, thereby, raised. The durability of the pore structure may also be an issue, with a possible disadvantage of finer scale structures being poor microstructural stability under service conditions. Finally, good mechanical properties may be required, since the development of thermal gradients, high fluid fluxes, etc. can generate substantial levels of stress. There are, thus, some complex interplays between service conditions, pore architecture/scale, fluid permeation characteristics, convective heat flow, thermal conduction and radiative heat transfer. Such interplays are illustrated with reference to three examples: (i) a thermal barrier coating in a gas turbine engine; (ii) a Space Shuttle tile; and (iii) a Stirling engine heat exchanger. Highly porous, permeable materials are often made by bonding fibres together into a network structure and much of the analysis presented here is oriented towards such materials.

  4. Novel-porous-Ag0 nanocomposite hydrogels via green process for advanced antibacterial applications.

    PubMed

    Vimala, Kanikireddy; Kanny, K; Varaprasad, Kokkarachedu; Kumar, N Mithil; Reddy, G S M

    2014-12-01

    Silver nanoparticles (NPs) antibacterial characteristics were depends on its particle stabilization, particles size and nucleation agent. In this study, we report on green process of porous silver nanocomposite hydrogels for advanced antibacterial applications. The porous poly(acrylamide) (PAM) hydrogels were developed employing sucrose as porogenator. Silver NPs were nucleated with natural biomass Neem (Azadirachta indica) leaf extracts within the porous hydrogel networks. The formation of silver NPs in the porous hydrogels was confirmed by ultraviolet-visible spectroscopy, fourier transform infrared spectroscopy, X-ray diffraction, and thermo gravimetric analysis. Morphological studies done by scanning electron microscopy and transmission electron microscopy showed that the hydrogels were porous in nature and stabilization of NPs, size, and particles shape. The porous PAM silver nanoparticle hydrogels demonstrated excellent antimicrobial activity with significant effect against Escherichia coli, Micrococcus, and Candida albicus. Hence, it was clear that the developed hydrogels can be used effectively for preventing and treating infections.

  5. Atomic layer deposition HfO2 capping layer effect on porous low dielectric constant materials

    NASA Astrophysics Data System (ADS)

    Cheng, Yi-Lung; Kao, Kai-Chieh; Huang, Chi-Jia; Chen, Giin-Shan; Fang, Jau-Shiung

    2015-11-01

    Low dielectric constant (low-k) materials are used as inter-level insulators between copper (Cu) conductors to improve the characteristics of integrated circuits. This work proposes a new method for improving the characteristics of porous low-k dielectric film by capping it with an HfO2 film by atomic layer deposition (ALD). Experimental results revealed that capping a porous low-k dielectric film with a ∼1.0 nm-thick HfO2 film increases its dielectric constant from 2.56 to 2.65 because the pores in the surface of the film are sealed by Hf precursors. The leakage current density and reliability of the porous low-k dielectrics are greatly improved. The HfO2 capping film also increased resistances against Cu diffusion and damage by oxygen plasma. Therefore, this ALD-deposited HfO2 capping film can be used as a pore-sealing layer and a Cu barrier layer for the porous low-k dielectric film in the future advanced technologies.

  6. Session: CSP Advanced Systems: Optical Materials (Presentation)

    SciTech Connect

    Kennedy, C.

    2008-04-01

    The Optical Materials project description is to characterize advanced reflector, perform accelerated and outdoor testing of commercial and experimental reflector materials, and provide industry support.

  7. Avalanches in compressed porous SiO(2)-based materials.

    PubMed

    Nataf, Guillaume F; Castillo-Villa, Pedro O; Baró, Jordi; Illa, Xavier; Vives, Eduard; Planes, Antoni; Salje, Ekhard K H

    2014-08-01

    The failure dynamics in SiO(2)-based porous materials under compression, namely the synthetic glass Gelsil and three natural sandstones, has been studied for slowly increasing compressive uniaxial stress with rates between 0.2 and 2.8 kPa/s. The measured collapsed dynamics is similar to Vycor, which is another synthetic porous SiO(2) glass similar to Gelsil but with a different porous mesostructure. Compression occurs by jerks of strain release and a major collapse at the failure point. The acoustic emission and shrinking of the samples during jerks are measured and analyzed. The energy of acoustic emission events, its duration, and waiting times between events show that the failure process follows avalanche criticality with power law statistics over ca. 4 decades with a power law exponent ɛ≃ 1.4 for the energy distribution. This exponent is consistent with the mean-field value for the collapse of granular media. Besides the absence of length, energy, and time scales, we demonstrate the existence of aftershock correlations during the failure process.

  8. Characterizing He 2 flow through porous materials using counterflow data

    NASA Technical Reports Server (NTRS)

    Vansciver, Steven W.; Maddocks, J. R.

    1991-01-01

    Proposed space applications, such as the cooling of infrared and x ray telescopes, have generated substantial interest in the behavior of He(2) flowing in porous materials. For design purposes, classical porous media correlations and room temperature data are often used to obtain order of magnitude estimates of expected pressure drops, while the attendant temperature differences are either ignored or estimated using smooth tube correlations. A more accurate alternative to this procedure is suggested by an empirical extension of the two fluid models. It is shown that four empirical parameters are necessary to describe the pressure and temperature differences induced by He(2) flow through a porous sample. The three parameters required to determine pressure differences are measured in counterflow and found to compare favorably with those for isothermal flow. The fourth parameter, the Gorter-Mellink constant, differs substantially from smooth tube values. It is concluded that parameter values determined from counterflow can be used to predict pressure and temperature differences in a variety of flows to an accuracy of about + or - 20 percent.

  9. Characterizing He II flow through porous materials using counterflow data

    NASA Technical Reports Server (NTRS)

    Maddocks, J. R., Jr.; Vansciver, Steven W.

    1990-01-01

    Proposed space applications, such as the cooling of infrared and x ray telescopes, have generated substantial interest in the behavior of He II flowing in porous materials. For design purposes, classical porous media correlations and room temperature data are often used to obtain order of magnitude estimates of expected pressure drops, while the attendant temperature differences are either ignored or estimated using smooth tube correlations. A more accurate alternative to this procedure is suggested by an empirical extension of the two fluid model. It is shown that four empirical parameters are necessary to describe the pressure and temperature differences induced by He II flow through a porous sample. The three parameters required to determine pressure differences are measured in counterflow and found to compare favorably with those for isothermal flow. The fourth parameter, the Gorter-Mellink constant, differs substantially from smooth tube values. It is concluded that parameter values determined from counterflow can be used to predict pressure and temperature differences in a variety of flows to an accuracy of about + or - 20 pct.

  10. Water-based technique to produce porous PZT materials

    NASA Astrophysics Data System (ADS)

    Galassi, C.; Capiani, C.; Craciun, F.; Roncari, E.

    2005-09-01

    Water based colloidal processing of PZT materials was investigated in order to reduce costs and employ more environmental friendly manufacturing. The technique addressed was the production of porous thick samples by the so called “starch consolidation”. PZT “soft” compositions were used. The “starch consolidation” process allows to obtain the green body by raising the temperature of a suspension of PZT powder, soluble starch and water, cast into a metal mould. The influence of the processing parameters and composition on the morphology, pore volumes, pore size distributions and piezoelectric properties are investigated. Zeta potential determination and titration with different deflocculants were essential tools to adjust the slurry formulation.

  11. Synergistic Carbon Dioxide Capture and Conversion in Porous Materials.

    PubMed

    Zhang, Yugen; Lim, Diane S W

    2015-08-24

    Global climate change and excessive CO2 emissions have caused widespread public concern in recent years. Tremendous efforts have been made towards CO2 capture and conversion. This has led to the development of numerous porous materials as CO2 capture sorbents. Concurrently, the conversion of CO2 into value-added products by chemical methods has also been well-documented recently. However, realizing the attractive prospect of direct, in situ chemical conversion of captured CO2 into other chemicals remains a challenge.

  12. Acoustic structure and propagation in highly porous, layered, fibrous materials

    NASA Technical Reports Server (NTRS)

    Lambert, R. F.; Tesar, J. S.

    1984-01-01

    The acoustic structure and propagation of sound in highly porous, layered, fine fiber materials is examined. Of particular interest is the utilization of the Kozeny number for determining the static flow resistance and the static structure factor based on flow permeability measurements. In this formulation the Kozeny number is a numerical constant independent of volume porosity at high porosities. The other essential parameters are then evaluated employing techniques developed earlier for open cell foams. The attenuation and progressive phase characteristics in bulk samples are measured and compared with predicted values. The agreements on the whole are very satisfactory.

  13. The usable capacity of porous materials for hydrogen storage

    NASA Astrophysics Data System (ADS)

    Schlichtenmayer, Maurice; Hirscher, Michael

    2016-04-01

    A large number of different porous materials has been investigated for their hydrogen uptake over a wide pressure range and at different temperature. From the absolute adsorption isotherms, the enthalpy of adsorption is evaluated for a wide range of surface coverage. The usable capacity, defined as the amount of hydrogen released between a maximum tank pressure and a minimum back pressure for a fuel cell, is analyzed for isothermal operation. The usable capacity as a function of temperature shows a maximum which defines the optimum operating temperature. This optimum operating temperature is higher for materials possessing a higher enthalpy of adsorption. However, the fraction of the hydrogen stored overall that can be released at the optimum operating temperature is higher for materials with a lower enthalpy of adsorption than for the ones with higher enthalpy.

  14. Basalt fiber reinforced porous aggregates-geopolymer based cellular material

    NASA Astrophysics Data System (ADS)

    Luo, Xin; Xu, Jin-Yu; Li, Weimin

    2015-09-01

    Basalt fiber reinforced porous aggregates-geopolymer based cellular material (BFRPGCM) was prepared. The stress-strain curve has been worked out. The ideal energy-absorbing efficiency has been analyzed and the application prospect has been explored. The results show the following: fiber reinforced cellular material has successively sized pore structures; the stress-strain curve has two stages: elastic stage and yielding plateau stage; the greatest value of the ideal energy-absorbing efficiency of BFRPGCM is 89.11%, which suggests BFRPGCM has excellent energy-absorbing property. Thus, it can be seen that BFRPGCM is easy and simple to make, has high plasticity, low density and excellent energy-absorbing features. So, BFRPGCM is a promising energy-absorbing material used especially in civil defense engineering.

  15. Advanced Materials for Space Applications

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H.; Curto, Paul A.

    2005-01-01

    Since NASA was created in 1958, over 6400 patents have been issued to the agency--nearly one in a thousand of all patents ever issued in the United States. A large number of these inventions have focused on new materials that have made space travel and exploration of the moon, Mars, and the outer planets possible. In the last few years, the materials developed by NASA Langley Research Center embody breakthroughs in performance and properties that will enable great achievements in space. The examples discussed below offer significant advantages for use in small satellites, i.e., those with payloads under a metric ton. These include patented products such as LaRC SI, LaRC RP 46, LaRC RP 50, PETI-5, TEEK, PETI-330, LaRC CP, TOR-LM and LaRC LCR (patent pending). These and other new advances in nanotechnology engineering, self-assembling nanostructures and multifunctional aerospace materials are presented and discussed below, and applications with significant technological and commercial advantages are proposed.

  16. Advanced materials for space applications

    NASA Astrophysics Data System (ADS)

    Pater, Ruth H.; Curto, Paul A.

    2007-12-01

    Since NASA was created in 1958, over 6400 patents have been issued to the agency—nearly one in a thousand of all patents ever issued in the United States. A large number of these inventions have focused on new materials that have made space travel and exploration of the moon, Mars, and the outer planets possible. In the last few years, the materials developed by NASA Langley Research Center embody breakthroughs in performance and properties that will enable great achievements in space. The examples discussed below offer significant advantages for use in small satellites, i.e., those with payloads under a metric ton. These include patented products such as LaRC SI, LaRC RP 46, LaRC RP 50, PETI-5, TEEK, PETI-330, LaRC CP, TOR-LM and LaRC LCR (patent pending). These and other new advances in nanotechnology engineering, self-assembling nanostructures and multifunctional aerospace materials are presented and discussed below, and applications with significant technological and commercial advantages are proposed.

  17. Materials Advance Chemical Propulsion Technology

    NASA Technical Reports Server (NTRS)

    2012-01-01

    In the future, the Planetary Science Division of NASA's Science Mission Directorate hopes to use better-performing and lower-cost propulsion systems to send rovers, probes, and observers to places like Mars, Jupiter, and Saturn. For such purposes, a new propulsion technology called the Advanced Materials Bipropellant Rocket (AMBR) was developed under NASA's In-Space Propulsion Technology (ISPT) project, located at Glenn Research Center. As an advanced chemical propulsion system, AMBR uses nitrogen tetroxide oxidizer and hydrazine fuel to propel a spacecraft. Based on current research and development efforts, the technology shows great promise for increasing engine operation and engine lifespan, as well as lowering manufacturing costs. In developing AMBR, ISPT has several goals: to decrease the time it takes for a spacecraft to travel to its destination, reduce the cost of making the propulsion system, and lessen the weight of the propulsion system. If goals like these are met, it could result in greater capabilities for in-space science investigations. For example, if the amount (and weight) of propellant required on a spacecraft is reduced, more scientific instruments (and weight) could be added to the spacecraft. To achieve AMBR s maximum potential performance, the engine needed to be capable of operating at extremely high temperatures and pressure. To this end, ISPT required engine chambers made of iridium-coated rhenium (strong, high-temperature metallic elements) that allowed operation at temperatures close to 4,000 F. In addition, ISPT needed an advanced manufacturing technique for better coating methods to increase the strength of the engine chamber without increasing the costs of fabricating the chamber.

  18. Modelling dynamic compaction of porous materials with the overstress approach

    NASA Astrophysics Data System (ADS)

    Partom, Y.

    2014-05-01

    To model compaction of a porous material we need 1) an equation of state of the porous material in terms of the equation of state of its matrix, and 2) a compaction law. For an equation of state it is common to use Herrmann's suggestion, as in his Pα model. For a compaction law it is common to use a quasi-static compaction relation obtained from 1) a meso-scale model (as in Carroll and Holt's spherical shell model), or from 2) quasi-static tests. Here we are interested in dynamic compaction, like in a planar impact test. In dynamic compaction the state may change too fast for the state point to follow the quasi-static compaction curve. We therefore get an overstress situation. The state point moves out of the quasi-static compaction boundary, and only with time collapses back towards it at a certain rate. In this way the dynamic compaction event becomes rate dependent. In the paper we first write down the rate equations for dynamic compaction according to the overstress approach. We then implement these equations in a hydro-code and run some examples. We show how the overstress rate parameter can be calibrated from tests.

  19. Fabrication and application of advanced functional materials from lignincellulosic biomass

    NASA Astrophysics Data System (ADS)

    Hu, Sixiao

    This dissertation explored the conversion of lignocellulosic biomass into advanced functional materials and their potential applications. Lignocellulosic biomass represents an as-of-yet underutilized renewable source for not only biofuel production but also functional materials fabrication. This renewable source is a great alternative for fossil fuel based chemicals, which could be one of the solutions to energy crisis. In this work, it was demonstrated a variety of advanced materials including functional carbons, metal and silica nanoparticles could be derived from lignocellulosic biomass. Chapter 1 provided overall reviewed of the lignin structures, productions and its utilizations as plastics, absorbents and carbons, as well as the preparation of nano-structured silver, silica and silicon carbide/nitride from biomass. Chapter 2, 3 and 4 discussed the fabrication of highly porous carbons from isolated lignin, and their applications as electric supercapacitors for energy storage. In chapter 2, ultrafine porous carbon fibers were prepared via electrospinning followed by simultaneous carbonization and activation. Chapter 3 covered the fabrication of supercapacitor based on the porous carbon fibers and the investigation of their electrochemical performances. In chapter 4, porous carbon particulates with layered carbon nano plates structures were produced by simple oven-drying followed by simultaneous carbonization and activation. The effects of heat processing parameters on the resulting carbon structures and their electrochemical properties were discussed in details. Chapter 5 and 6 addressed the preparation of silver nanoparticles using lignin. Chapter 5 reported the synthesis, underlying kinetics and mechanism of monodispersed silver nanospheres with diameter less than 25 nm in aqueous solutions using lignin as dual reducing and capping agents. Chapter 6 covered the preparation of silver nanoparticles on electrospun celluloses ultrafine fibers using lignin as both

  20. Characterization of porous carbon fibers and related materials

    SciTech Connect

    Fuller, E.L. Jr.

    1996-07-15

    This program was geared to support the Fossil Energy Material Sciences Program with respect to several areas of interest in efficient production and utilization of energy. Carbon molecular sieves have great potential for economically purifying gases; i.e. removal of carbon dioxide from natural gas without having to resort to cryogenic techniques. Microporous carbons can be tailored to serve as adsorbents for natural gas in on-board storage in automotive applications, avoiding high pressures and heavy storage tanks. This program is a laboratory study to evaluate production methodologies and activation processes to produce porous carbons for specific applications. The Carbon Materials Technology Group of Oak Ridge National Laboratory (ORNL) is engaged in developmental programs to produce activated carbon fibers (ACF) for applications in fixed beds and/or flowing reactors engineering applications.

  1. System level permeability modeling of porous hydrogen storage materials.

    SciTech Connect

    Kanouff, Michael P.; Dedrick, Daniel E.; Voskuilen, Tyler

    2010-01-01

    A permeability model for hydrogen transport in a porous material is successfully applied to both laboratory-scale and vehicle-scale sodium alanate hydrogen storage systems. The use of a Knudsen number dependent relationship for permeability of the material in conjunction with a constant area fraction channeling model is shown to accurately predict hydrogen flow through the reactors. Generally applicable model parameters were obtained by numerically fitting experimental measurements from reactors of different sizes and aspect ratios. The degree of channeling was experimentally determined from the measurements and found to be 2.08% of total cross-sectional area. Use of this constant area channeling model and the Knudsen dependent Young & Todd permeability model allows for accurate prediction of the hydrogen uptake performance of full-scale sodium alanate and similar metal hydride systems.

  2. Sol-gel Technology and Advanced Electrochemical Energy Storage Materials

    NASA Technical Reports Server (NTRS)

    Chu, Chung-tse; Zheng, Haixing

    1996-01-01

    Advanced materials play an important role in the development of electrochemical energy devices such as batteries, fuel cells, and electrochemical capacitors. The sol-gel process is a versatile solution for use in the fabrication of ceramic materials with tailored stoichiometry, microstructure, and properties. This processing technique is particularly useful in producing porous materials with high surface area and low density, two of the most desirable characteristics for electrode materials. In addition,the porous surface of gels can be modified chemically to create tailored surface properties, and inorganic/organic micro-composites can be prepared for improved material performance device fabrication. Applications of several sol-gel derived electrode materials in different energy storage devices are illustrated in this paper. V2O5 gels are shown to be a promising cathode material for solid state lithium batteries. Carbon aerogels, amorphous RuO2 gels and sol-gel derived hafnium compounds have been studied as electrode materials for high energy density and high power density electrochemical capacitors.

  3. In silico design of porous polymer networks: high-throughput screening for methane storage materials.

    PubMed

    Martin, Richard L; Simon, Cory M; Smit, Berend; Haranczyk, Maciej

    2014-04-01

    Porous polymer networks (PPNs) are a class of advanced porous materials that combine the advantages of cheap and stable polymers with the high surface areas and tunable chemistry of metal-organic frameworks. They are of particular interest for gas separation or storage applications, for instance, as methane adsorbents for a vehicular natural gas tank or other portable applications. PPNs are self-assembled from distinct building units; here, we utilize commercially available chemical fragments and two experimentally known synthetic routes to design in silico a large database of synthetically realistic PPN materials. All structures from our database of 18,000 materials have been relaxed with semiempirical electronic structure methods and characterized with Grand-canonical Monte Carlo simulations for methane uptake and deliverable (working) capacity. A number of novel structure-property relationships that govern methane storage performance were identified. The relationships are translated into experimental guidelines to realize the ideal PPN structure. We found that cooperative methane-methane attractions were present in all of the best-performing materials, highlighting the importance of guest interaction in the design of optimal materials for methane storage.

  4. Advanced materials: Information and analysis needs

    SciTech Connect

    Curlee, T.R.; Das, S.; Lee, R.; Trumble, D.

    1990-09-01

    This report presents the findings of a study to identify the types of information and analysis that are needed for advanced materials. The project was sponsored by the US Bureau of Mines (BOM). It includes a conceptual description of information needs for advanced materials and the development and implementation of a questionnaire on the same subject. This report identifies twelve fundamental differences between advanced and traditional materials and discusses the implications of these differences for data and analysis needs. Advanced and traditional materials differ significantly in terms of physical and chemical properties. Advanced material properties can be customized more easily. The production of advanced materials may differ from traditional materials in terms of inputs, the importance of by-products, the importance of different processing steps (especially fabrication), and scale economies. The potential for change in advanced materials characteristics and markets is greater and is derived from the marriage of radically different materials and processes. In addition to the conceptual study, a questionnaire was developed and implemented to assess the opinions of people who are likely users of BOM information on advanced materials. The results of the questionnaire, which was sent to about 1000 people, generally confirm the propositions set forth in the conceptual part of the study. The results also provide data on the categories of advanced materials and the types of information that are of greatest interest to potential users. 32 refs., 1 fig., 12 tabs.

  5. Approach to failure in porous granular materials under compression

    NASA Astrophysics Data System (ADS)

    Kun, Ferenc; Varga, Imre; Lennartz-Sassinek, Sabine; Main, Ian G.

    2013-12-01

    We investigate the approach to catastrophic failure in a model porous granular material undergoing uniaxial compression. A discrete element computational model is used to simulate both the microstructure of the material and the complex dynamics and feedbacks involved in local fracturing and the production of crackling noise. Under strain-controlled loading, microcracks initially nucleate in an uncorrelated way all over the sample. As loading proceeds the damage localizes into a narrow damage band inclined at 30∘-45∘ to the load direction. Inside the damage band the material is crushed into a poorly sorted mixture of mainly fine powder hosting some larger fragments. The mass probability density distribution of particles in the damage zone is a power law of exponent 2.1, similar to a value of 1.87 inferred from observations of the length distribution of wear products (gouge) in natural and laboratory faults. Dynamic bursts of radiated energy, analogous to acoustic emissions observed in laboratory experiments on porous sedimentary rocks, are identified as correlated trails or cascades of local ruptures that emerge from the stress redistribution process. As the system approaches macroscopic failure consecutive bursts become progressively more correlated. Their size distribution is also a power law, with an equivalent Gutenberg-Richter b value of 1.22 averaged over the whole test, ranging from 3 to 0.5 at the time of failure, all similar to those observed in laboratory tests on granular sandstone samples. The formation of the damage band itself is marked by a decrease in the average distance between consecutive bursts and an emergent power-law correlation integral of event locations with a correlation dimension of 2.55, also similar to those observed in the laboratory (between 2.75 and 2.25).

  6. Approach to failure in porous granular materials under compression.

    PubMed

    Kun, Ferenc; Varga, Imre; Lennartz-Sassinek, Sabine; Main, Ian G

    2013-12-01

    We investigate the approach to catastrophic failure in a model porous granular material undergoing uniaxial compression. A discrete element computational model is used to simulate both the microstructure of the material and the complex dynamics and feedbacks involved in local fracturing and the production of crackling noise. Under strain-controlled loading, microcracks initially nucleate in an uncorrelated way all over the sample. As loading proceeds the damage localizes into a narrow damage band inclined at 30°-45° to the load direction. Inside the damage band the material is crushed into a poorly sorted mixture of mainly fine powder hosting some larger fragments. The mass probability density distribution of particles in the damage zone is a power law of exponent 2.1, similar to a value of 1.87 inferred from observations of the length distribution of wear products (gouge) in natural and laboratory faults. Dynamic bursts of radiated energy, analogous to acoustic emissions observed in laboratory experiments on porous sedimentary rocks, are identified as correlated trails or cascades of local ruptures that emerge from the stress redistribution process. As the system approaches macroscopic failure consecutive bursts become progressively more correlated. Their size distribution is also a power law, with an equivalent Gutenberg-Richter b value of 1.22 averaged over the whole test, ranging from 3 to 0.5 at the time of failure, all similar to those observed in laboratory tests on granular sandstone samples. The formation of the damage band itself is marked by a decrease in the average distance between consecutive bursts and an emergent power-law correlation integral of event locations with a correlation dimension of 2.55, also similar to those observed in the laboratory (between 2.75 and 2.25). PMID:24483436

  7. Conductive porous scaffolds as potential neural interface materials.

    SciTech Connect

    Hedberg-Dirk, Elizabeth L.; Cicotte, Kirsten N.; Buerger, Stephen P.; Reece, Gregory; Dirk, Shawn M.; Lin, Patrick P.

    2011-11-01

    Our overall intent is to develop improved prosthetic devices with the use of nerve interfaces through which transected nerves may grow, such that small groups of nerve fibers come into close contact with electrode sites, each of which is connected to electronics external to the interface. These interfaces must be physically structured to allow nerve fibers to grow through them, either by being porous or by including specific channels for the axons. They must be mechanically compatible with nerves such that they promote growth and do not harm the nervous system, and biocompatible to promote nerve fiber growth and to allow close integration with biological tissue. They must exhibit selective and structured conductivity to allow the connection of electrode sites with external circuitry, and electrical properties must be tuned to enable the transmission of neural signals. Finally, the interfaces must be capable of being physically connected to external circuitry, e.g. through attached wires. We have utilized electrospinning as a tool to create conductive, porous networks of non-woven biocompatible fibers in order to meet the materials requirements for the neural interface. The biocompatible fibers were based on the known biocompatible material poly(dimethyl siloxane) (PDMS) as well as a newer biomaterial developed in our laboratories, poly(butylene fumarate) (PBF). Both of the polymers cannot be electrospun using conventional electrospinning techniques due to their low glass transition temperatures, so in situ crosslinking methodologies were developed to facilitate micro- and nano-fiber formation during electrospinning. The conductivity of the electrospun fiber mats was controlled by controlling the loading with multi-walled carbon nanotubes (MWNTs). Fabrication, electrical and materials characterization will be discussed along with initial in vivo experimental results.

  8. Approach to failure in porous granular materials under compression.

    PubMed

    Kun, Ferenc; Varga, Imre; Lennartz-Sassinek, Sabine; Main, Ian G

    2013-12-01

    We investigate the approach to catastrophic failure in a model porous granular material undergoing uniaxial compression. A discrete element computational model is used to simulate both the microstructure of the material and the complex dynamics and feedbacks involved in local fracturing and the production of crackling noise. Under strain-controlled loading, microcracks initially nucleate in an uncorrelated way all over the sample. As loading proceeds the damage localizes into a narrow damage band inclined at 30°-45° to the load direction. Inside the damage band the material is crushed into a poorly sorted mixture of mainly fine powder hosting some larger fragments. The mass probability density distribution of particles in the damage zone is a power law of exponent 2.1, similar to a value of 1.87 inferred from observations of the length distribution of wear products (gouge) in natural and laboratory faults. Dynamic bursts of radiated energy, analogous to acoustic emissions observed in laboratory experiments on porous sedimentary rocks, are identified as correlated trails or cascades of local ruptures that emerge from the stress redistribution process. As the system approaches macroscopic failure consecutive bursts become progressively more correlated. Their size distribution is also a power law, with an equivalent Gutenberg-Richter b value of 1.22 averaged over the whole test, ranging from 3 to 0.5 at the time of failure, all similar to those observed in laboratory tests on granular sandstone samples. The formation of the damage band itself is marked by a decrease in the average distance between consecutive bursts and an emergent power-law correlation integral of event locations with a correlation dimension of 2.55, also similar to those observed in the laboratory (between 2.75 and 2.25).

  9. Advancing Porous Silicon Biosensor Technology for Use in Clinical Diagnostics

    NASA Astrophysics Data System (ADS)

    Bonanno, Lisa Marie

    Inexpensive and robust analytical techniques for detecting molecular recognition events are in great demand in healthcare, food safety, and environmental monitoring. Despite vast research in this area, challanges remain to develop practical biomolecular platforms that, meet the rigorous demands of real-world applications. This includes maintaining low-cost devices that are sensitive and specific in complex test specimens, are stable after storage, have short assay time, and possess minimal complexity of instrumentation for readout. Nanostructured porous silicon (PSi) material has been identified as an ideal candidate towards achieving these goals and the past decade has seen diverse proof-of-principle studies developing optical-based sensing techniques. In Part 1 of this thesis, the impact of surface chemistry and PSi morphology on detection sensitivity of target molecules is investigated. Initial proof-of-concept that PSi devices facilitate detection of protein in whole blood is demonstrated. This work highlights the importance of material stability and blocking chemistry for sensor use in real world biological samples. In addition, the intrinisic filtering capability of the 3-D PSi morphology is shown as an advantage in complex solutions, such as whole blood. Ultimately, this initial work identified a need to improve detection sensitivity of the PSI biosensor technique to facilitate clinical diagnostic use over relevant target concentration ranges. The second part of this thesis, builds upon sensitivity challenges that are highlighted in the first part of the thesis and development of a surface-bound competitive inhibition immunoassay facilitated improved detection sensitivity of small molecular weight targets (opiates) over a relevant clinical concentration range. In addition, optimization of assay protocol addressed issues of maintaining stability of sensors after storage. Performance of the developed assay (specificity and sensitivity) was then validated in a

  10. Bioinspired large-scale aligned porous materials assembled with dual temperature gradients

    PubMed Central

    Bai, Hao; Chen, Yuan; Delattre, Benjamin; Tomsia, Antoni P.; Ritchie, Robert O.

    2015-01-01

    Natural materials, such as bone, teeth, shells, and wood, exhibit outstanding properties despite being porous and made of weak constituents. Frequently, they represent a source of inspiration to design strong, tough, and lightweight materials. Although many techniques have been introduced to create such structures, a long-range order of the porosity as well as a precise control of the final architecture remain difficult to achieve. These limitations severely hinder the scale-up fabrication of layered structures aimed for larger applications. We report on a bidirectional freezing technique to successfully assemble ceramic particles into scaffolds with large-scale aligned, lamellar, porous, nacre-like structure and long-range order at the centimeter scale. This is achieved by modifying the cold finger with a polydimethylsiloxane (PDMS) wedge to control the nucleation and growth of ice crystals under dual temperature gradients. Our approach could provide an effective way of manufacturing novel bioinspired structural materials, in particular advanced materials such as composites, where a higher level of control over the structure is required. PMID:26824062

  11. Bioinspired large-scale aligned porous materials assembled with dual temperature gradients.

    PubMed

    Bai, Hao; Chen, Yuan; Delattre, Benjamin; Tomsia, Antoni P; Ritchie, Robert O

    2015-12-01

    Natural materials, such as bone, teeth, shells, and wood, exhibit outstanding properties despite being porous and made of weak constituents. Frequently, they represent a source of inspiration to design strong, tough, and lightweight materials. Although many techniques have been introduced to create such structures, a long-range order of the porosity as well as a precise control of the final architecture remain difficult to achieve. These limitations severely hinder the scale-up fabrication of layered structures aimed for larger applications. We report on a bidirectional freezing technique to successfully assemble ceramic particles into scaffolds with large-scale aligned, lamellar, porous, nacre-like structure and long-range order at the centimeter scale. This is achieved by modifying the cold finger with a polydimethylsiloxane (PDMS) wedge to control the nucleation and growth of ice crystals under dual temperature gradients. Our approach could provide an effective way of manufacturing novel bioinspired structural materials, in particular advanced materials such as composites, where a higher level of control over the structure is required. PMID:26824062

  12. Advanced morphological analysis of patterns of thin anodic porous alumina

    SciTech Connect

    Toccafondi, C.; Stępniowski, W.J.; Leoncini, M.; Salerno, M.

    2014-08-15

    Different conditions of fabrication of thin anodic porous alumina on glass substrates have been explored, obtaining two sets of samples with varying pore density and porosity, respectively. The patterns of pores have been imaged by high resolution scanning electron microscopy and analyzed by innovative methods. The regularity ratio has been extracted from radial profiles of the fast Fourier transforms of the images. Additionally, the Minkowski measures have been calculated. It was first observed that the regularity ratio averaged across all directions is properly corrected by the coefficient previously determined in the literature. Furthermore, the angularly averaged regularity ratio for the thin porous alumina made during short single-step anodizations is lower than that of hexagonal patterns of pores as for thick porous alumina from aluminum electropolishing and two-step anodization. Therefore, the regularity ratio represents a reliable measure of pattern order. At the same time, the lower angular spread of the regularity ratio shows that disordered porous alumina is more isotropic. Within each set, when changing either pore density or porosity, both regularity and isotropy remain rather constant, showing consistent fabrication quality of the experimental patterns. Minor deviations are tentatively discussed with the aid of the Minkowski measures, and the slight decrease in both regularity and isotropy for the final data-points of the porosity set is ascribed to excess pore opening and consequent pore merging. - Highlights: • Thin porous alumina is partly self-ordered and pattern analysis is required. • Regularity ratio is often misused: we fix the averaging and consider its spread. • We also apply the mathematical tool of Minkowski measures, new in this field. • Regularity ratio shows pattern isotropy and Minkowski helps in assessment. • General agreement with perfect artificial patterns confirms the good manufacturing.

  13. The pressure drop in a porous material layer during combustion

    SciTech Connect

    Kondrikov, B.N.

    1995-07-01

    During the combustion of a porous material layer, a manometer, which is attached to the cold end of the charge, records at the bottom of the layer a pressure reduction, which was discovered more than 20 years ago but which remains essentially unexplained up to the present. It is experimentally shown that this effect is similar to the pressure change in the cavities when a light gas (helium, hydrogen) diffuses from (or to) them under isothermal conditions and that it increases during the combustion mainly due to the accompanying Stefan type flow, and probably also as a result of the thermal diffusion. A pressure drop in the cavities is evidently made possible also by the pressure reduction in the flame which follows from the Hugoniot adiabatic theory.

  14. Salt transport and crystallization in porous building materials.

    PubMed

    Pel, L; Huinink, H; Kopinga, K

    2003-01-01

    Salt weathering is a major cause of deterioration of porous building materials. To obtain information about the mechanisms underlying these damage processes we have studied the moisture and ion transport. We measured the time evolution of NaCl saturated samples of fired-clay brick during one-sided drying using Nuclear Magnetic Resonance. The moisture content and amount of dissolved Na ions could be measured quantitatively as a function of position. The NaCl concentration profiles obtained from these data reflect the competition between advection to the surface and redistribution by diffusion. By representing the measured moisture and NaCl profiles in an efflorescence pathway diagram (EPD) also the crystallization can be taken into account.

  15. Advanced Reflector and Absorber Materials (Fact Sheet)

    SciTech Connect

    Not Available

    2010-08-01

    Fact sheet describing NREL CSP Program capabilities in the area of advanced reflector and absorber materials: evaluating performance, determining degradation rates and lifetime, and developing new coatings.

  16. Porous multi-component material for the capture and separation of species of interest

    DOEpatents

    Addleman, Raymond S.; Chouyyok, Wilaiwan; Li, Xiaohong S.; Cinson, Anthony D.; Gerasimenko, Aleksandr A

    2016-06-21

    A method and porous multi-component material for the capture, separation or chemical reaction of a species of interest is disclosed. The porous multi-component material includes a substrate and a composite thin film. The composite thin film is formed by combining a porous polymer with a nanostructured material. The nanostructured material may include a surface chemistry for the capture of chemicals or particles. The composite thin film is coupled to the support or device surface. The method and material provides a simple, fast, and chemically and physically benign way to integrate nanostructured materials into devices while preserving their chemical activity.

  17. Metal-organic frameworks as functional, porous materials

    NASA Astrophysics Data System (ADS)

    Rood, Jeffrey A.

    The research presented in this thesis investigates the use of metal carboxylates as permanently porous materials called metal-organic frameworks (MOFs). The project has focused on three broad areas of study, each which strives to develop a further understanding of this class of materials. The first topic is concerned with the synthesis and structural characterization of MOFs. Our group and others have found that the reaction of metal salts with carboxylic acids in polar solvents at elevated temperatures often leads the formation of crystalline MOF materials that can be examined by single crystal X-ray diffraction. Specifically, Chapter 2 reports on some of the first examples of magnesium MOFs, constructed from formate or aryldicarboxylate ligands. The magnesium formate MOF, [Mg3(O2CH) 6] was found to be a permanently porous 3-D material capable of selective uptake and exchange of small molecules. Once the synthesis and structures of some of these materials was known, their physical properties were studied. The magnesium formate MOF, [Mg 3(O2CH)6], was found to be permanently porous and able to reversibly adsorb both N2 and H2 gas. Furthermore, the material was also capable of taking up a variety of organic molecules to form new inclusion compounds that were characterized by XRD studies. Size exclusion was shown for cyclohexane and larger molecules. Chapters 3, 5, and 6 attempt to build off of the synthetic findings reported in Chapter 2. Specifically, the ability of these materials to take up guest molecules is expanded by the attempted synthesis of porous, homochiral MOFs using enantiopure carboxylic acids in the synthesis. It was found that under the appropriate synthetic conditions, both L-tartaric acid and (+)-camphoric acid were robust linkers for the formation of homochiral MOFs. Of the compounds synthesized, the most interesting were the set of compounds, [Zn2(Cam) 2(bipy)⊃3DMF] and [Zn2(Cam)2(apyr)⊃2DMF]. These compounds formed isoreticular cubic

  18. Molecular simulation of adsorption and transport in hierarchical porous materials.

    PubMed

    Coasne, Benoit; Galarneau, Anne; Gerardin, Corine; Fajula, François; Villemot, François

    2013-06-25

    Adsorption and transport in hierarchical porous solids with micro- (~1 nm) and mesoporosities (>2 nm) are investigated by molecular simulation. Two models of hierarchical solids are considered: microporous materials in which mesopores are carved out (model A) and mesoporous materials in which microporous nanoparticles are inserted (model B). Adsorption isotherms for model A can be described as a linear combination of the adsorption isotherms for pure mesoporous and microporous solids. In contrast, adsorption in model B departs from adsorption in pure microporous and mesoporous solids; the inserted microporous particles act as defects, which help nucleate the liquid phase within the mesopore and shift capillary condensation toward lower pressures. As far as transport under a pressure gradient is concerned, the flux in hierarchical materials consisting of microporous solids in which mesopores are carved out obeys the Navier-Stokes equation so that Darcy's law is verified within the mesopore. Moreover, the flow in such materials is larger than in a single mesopore, due to the transfer between micropores and mesopores. This nonzero velocity at the mesopore surface implies that transport in such hierarchical materials involves slippage at the mesopore surface, although the adsorbate has a strong affinity for the surface. In contrast to model A, flux in model B is smaller than in a single mesopore, as the nanoparticles act as constrictions that hinder transport. By a subtle effect arising from fast transport in the mesopores, the presence of mesopores increases the number of molecules in the microporosity in hierarchical materials and, hence, decreases the flow in the micropores (due to mass conservation). As a result, we do not observe faster diffusion in the micropores of hierarchical materials upon flow but slower diffusion, which increases the contact time between the adsorbate and the surface of the microporosity.

  19. Electronically and ionically conductive porous material and method for manufacture of resin wafers therefrom

    DOEpatents

    Lin, YuPo J.; Henry, Michael P.; Snyder, Seth W.

    2011-07-12

    An electrically and ionically conductive porous material including a thermoplastic binder and one or more of anion exchange moieties or cation exchange moieties or mixtures thereof and/or one or more of a protein capture resin and an electrically conductive material. The thermoplastic binder immobilizes the moieties with respect to each other but does not substantially coat the moieties and forms the electrically conductive porous material. A wafer of the material and a method of making the material and wafer are disclosed.

  20. Electronically and ionically conductive porous material and method for manufacture of resin wafers therefrom

    DOEpatents

    Lin, YuPo J.; Henry, Michael P.; Snyder, Seth W.

    2008-11-18

    An electrically and ionically conductive porous material including a thermoplastic binder and one or more of anion exchange moieties or cation exchange moieties or mixtures thereof and/or one or more of a protein capture resin and an electrically conductive material. The thermoplastic binder immobilizes the moieties with respect to each other but does not substantially coat the moieties and forms the electrically conductive porous material. A wafer of the material and a method of making the material and wafer are disclosed.

  1. Advanced Photon Source Upgrade Project - Materials

    ScienceCinema

    Gibbson, Murray

    2016-07-12

    An upgrade to Advanced Photon Source announced by DOE - http://go.usa.gov/ivZ -- will help scientists break through bottlenecks in materials design in order to develop materials with desirable functions.

  2. Dynamic behavior of particulate/porous energetic materials

    NASA Astrophysics Data System (ADS)

    Nesterenko, Vitali

    2011-06-01

    Dynamic behavior of particulate/porous energetic materials in a broad range of impact conditions and types of deformation (shock, shear) will be discussed. Samples of these materials were fabricated using Cold Isostatic Pressing, sintering and Hot Isostatic Pressing with and without vacuum encapsulation. The current interest in these materials is due to the combination of their high strength with energy efficiency under critical conditions of mechanical deformation. They may exhibit high compressive and tensile strength with the ability to bulk distributed fracture resulting in a small size reactive fragments and possible reaction on later stages. The results of dynamic deformation and fragmentation of these materials in conditions of low velocity (10 m/s), high energy impact, under localized deformation in single and multiple shear bands generated using explosively driven Thick Walled Cylinder method will be discussed. The mechanical properties of these materials are highly sensitive to mesostructure. For example, a dynamic strength of Al-W composites with fine W particles is significantly larger than the strength of composite with the coarse W particles at the same porosity. Morphology of W inclusions had a strong effect on dynamic strength. Samples with W wires arranged in axial direction with the same volume content of components had a highest dynamic strength. Porosity in these materials can provide a strain hardening mechanism effect due to in situ densification which was observed experimentally for cold isostatically pressed Al and Al-coarse W powders. Experimental results will be compared with available numerical data. The support for this project provided by ONR MURI N00014-07-1-0740 (Program Officer Dr. Clifford Bedford).

  3. Asymmetric Wicking and Reduced Evaporation Time of Droplets Penetrating a Thin Double-Layered Porous Material

    NASA Astrophysics Data System (ADS)

    Vahdani, Aria; Gat, Amir; Nowakowski, Albert; Navaz, Homayun; Gharib, Morteza

    2013-11-01

    We study numerically and experimentally the penetration and evaporation dynamics of droplets wicking into a thin double-layered porous material with order-of-magnitude difference in the physical properties (such as capillary pressure drop, porosity or permeability) between the layers. We show that such double-layered porous materials can be used to create highly asymmetrical wicking properties, preventing liquid droplets wicking from one surface to the other, while allowing for wicking in the reverse direction. In addition, these double-layered porous materials are shown to reduce the evaporation time of droplets penetrating into the porous surface, compared with a single-layered material of equal thickness and physical properties similar to either of the layers. The asymmetric wicking and reduced evaporation time demonstrated in such double-layered porous materials may be of interest to applications such as medical bandages and wearable fabrics.

  4. Facile synthesis of reduced graphene oxide-porous silicon composite as superior anode material for lithium-ion battery anodes

    NASA Astrophysics Data System (ADS)

    Jiao, Lian-Sheng; Liu, Jin-Yu; Li, Hong-Yan; Wu, Tong-Shun; Li, Fenghua; Wang, Hao-Yu; Niu, Li

    2016-05-01

    We report a new method for synthesizing reduced graphene oxide (rGO)-porous silicon composite for lithium-ion battery anodes. Rice husks were used as a as a raw material source for the synthesis of porous Si through magnesiothermic reduction process. The as-obtained composite exhibits good rate and cycling performance taking advantage of the porous structure of silicon inheriting from rice husks and the outstanding characteristic of graphene. A considerably high delithiation capacity of 907 mA h g-1 can be retained even at a rate of 16 A g-1. A discharge capacity of 830 mA h g-1 at a current density of 1 A g-1 was delivered after 200 cycles. This may contribute to the further advancement of Si-based composite anode design.

  5. Porous carbon spheres and monoliths: morphology control, pore size tuning and their applications as Li-ion battery anode materials.

    PubMed

    Roberts, Aled D; Li, Xu; Zhang, Haifei

    2014-07-01

    The development of the next generation of advanced lithium-ion batteries (LIBs) requires new & advanced materials and novel fabrication techniques in order to push the boundaries of performance and open up new and exciting markets. Structured carbon materials, with controlled pore features on the micron and nanometer scales, are explored as advanced alternatives to conventional graphite as the active material of the LIB anode. Mesoporous carbon materials, carbon nanotube-based materials, and graphene-based materials have been extensively investigated and reviewed. Morphology control (e.g., colloids, thin films, nanofibrous mats, monoliths) and hierarchical pores (particularly the presence of large pores) exhibit an increasing influence on LIB performance. This tutorial review focuses on the synthetic techniques for preparation of porous carbon spheres and carbon monoliths, including hydrothermal carbonization, emulsion templating, ice templating and new developments in making porous carbons from sustainable biomass and metal-organic framework templating. We begin with a brief introduction to LIBs, defining key parameters and terminology used to assess the performance of anode materials, and then address synthetic techniques for the fabrication of carbon spheres & monoliths and the relevant composites, followed, respectively, by a review of their performance as LIB anode materials. The review is completed with a prospective view on the possible direction of future research in this field.

  6. Video Fact Sheets: Everyday Advanced Materials

    SciTech Connect

    2015-10-06

    What are Advanced Materials? Ames Laboratory is behind some of the best advanced materials out there. Some of those include: Lead-Free Solder, Photonic Band-Gap Crystals, Terfenol-D, Aluminum-Calcium Power Cable and Nano Particles. Some of these are in products we use every day.

  7. Video Fact Sheets: Everyday Advanced Materials

    ScienceCinema

    None

    2016-07-12

    What are Advanced Materials? Ames Laboratory is behind some of the best advanced materials out there. Some of those include: Lead-Free Solder, Photonic Band-Gap Crystals, Terfenol-D, Aluminum-Calcium Power Cable and Nano Particles. Some of these are in products we use every day.

  8. Development of Specialized Advanced Materials Curriculum.

    ERIC Educational Resources Information Center

    Malmgren, Thomas; And Others

    This course is intended to give students a comprehensive experience in current and future manufacturing materials and processes. It familiarizes students with: (1) base of composite materials; (2) composites--a very light, strong material used in spacecraft and stealth aircraft; (3) laminates; (4) advanced materials--especially aluminum alloys;…

  9. Detection of water deposits and movement in porous materials by infrared imaging

    NASA Astrophysics Data System (ADS)

    Avdelidis, N. P.; Moropoulou, A.; Theoulakis, P.

    2003-06-01

    Since a large amount of damage in porous materials arises as a direct or indirect consequence of moisture (static and dynamic phenomena), detection and monitoring of moisture in porous materials is important, in an attempt to determine the actual damage, as well as the deterioration rate. The most common methodology to assess the moisture content in porous materials is to collect representative samples from the sites investigated and then weigh them before and after drying. In this research, infrared thermography, an indirect moisture assessment technique, was used in the investigation of various porous stones in the laboratory during capillary rise tests. Supplementary investigation of the stones in terms of their microstructure (mercury intrusion porosimetry) and isothermic behaviour (water sorption) was also performed. Finally, an in field diagnostic survey on historic structures was carried out. The results of this study indicate that infrared imaging provides significant information in the study of moisture in porous materials.

  10. Structure and Stability of Deflagrations in Porous Energetic Materials

    SciTech Connect

    stephen B. Margolis; Forman A. Williams

    1999-03-01

    Theoretical two-phase-flow analyses have recently been developed to describe the structure and stability of multi-phase deflagrations in porous energetic materials, in both confined and unconfined geometries. The results of these studies are reviewed, with an emphasis on the fundamental differences that emerge with respect to the two types of geometries. In particular, pressure gradients are usually negligible in unconfined systems, whereas the confined problem is generally characterized by a significant gas-phase pressure difference, or overpressure, between the burned and unburned regions. The latter leads to a strong convective influence on the burning rate arising from the pressure-driven permeation of hot gases into the solid/gas region and the consequent preheating of the unburned material. It is also shown how asymptotic models that are suitable for analyzing stability may be derived based on the largeness of an overall activation-energy parameter. From an analysis of such models, it is shown that the effects of porosity and two-phase flow are generally destabilizing, suggesting that degraded propellants, which exhibit greater porosity than their pristine counterparts, may be more readily subject to combustion instability and nonsteady deflagration.

  11. Recent advances in nanoscale bioinspired materials.

    PubMed

    Demirel, Melik C; Cetinkaya, Murat; Pena-Francesch, Abdon; Jung, Huihun

    2015-03-01

    Natural materials have been a fundamental part of human life since the dawn of civilization. However, due to exploitation of natural resources and cost issues, synthetic materials replaced bio-derived materials in the last century. Recent advances in bio- and nano-technologies pave the way for developing eco-friendly materials that could be produced easily from renewable resources at reduced cost and in a broad array of useful applications. This feature article highlights structural and functional characteristics of bio-derived materials, which will expedite the design fabrication and synthesis of eco-friendly and recyclable advanced nano-materials and devices.

  12. Attenuation of intense sinusoidal waves in air-saturated, bulk porous materials

    NASA Technical Reports Server (NTRS)

    Kuntz, Herbert L.; Blackstock, David T.

    1987-01-01

    As intense, initially sinusoidal waves propagate in fluids, shocks form and excess attenuation of the wave occurs. Data are presented indicating that shock formation is not necessary for the occurrence of excess attenuation in nonlinear, lossy media, i.e., air-saturated, porous materials. An empirical equation is used to describe the excess attenuation of intense sinusoids in porous materials. The acoustic nonlinearity of and the excess attenuation in porous materials may be predicted directly from dc flow resistivity data. An empirical relationship is used to relate an acoustic nonlinearity parameter to the fundamental frequency and relative dc nonlinearity of two structurally different materials.

  13. Recent Advances in Superhard Materials

    NASA Astrophysics Data System (ADS)

    Zhao, Zhisheng; Xu, Bo; Tian, Yongjun

    2016-07-01

    In superhard materials research, two topics are of central focus. One is to understand hardness microscopically and to establish hardness models with atomic parameters, which can be used to guide the design or prediction of novel superhard crystals. The other is to synthesize superhard materials with enhanced comprehensive performance (i.e., hardness, fracture toughness, and thermal stability), with the ambition of achieving materials harder than natural diamond. In this review, we present recent developments in both areas. The microscopic hardness models of covalent single crystals are introduced and further generalized to polycrystalline materials. Current research progress in novel superhard materials and nanostructuring approaches for high-performance superhard materials are discussed. We also clarify a long-standing controversy about the criterion for performing a reliable indentation hardness measurement.

  14. Natural sisal fibers derived hierarchical porous activated carbon as capacitive material in lithium ion capacitor

    NASA Astrophysics Data System (ADS)

    Yang, Zhewei; Guo, Huajun; Li, Xinhai; Wang, Zhixing; Yan, Zhiliang; Wang, Yansen

    2016-10-01

    Lithium-ion capacitor (LIC) is a novel advanced electrochemical energy storage (EES) system bridging gap between lithium ion battery (LIB) and electrochemical capacitor (ECC). In this work, we report that sisal fiber activated carbon (SFAC) was synthesized by hydrothermal treatment followed by KOH activation and served as capacitive material in LIC for the first time. Different particle structure, morphology, specific surface area and heteroatoms affected the electrochemical performance of as-prepared materials and corresponding LICs. When the mass ratio of KOH to char precursor was 2, hierarchical porous structured SFAC-2 was prepared and exhibited moderate specific capacitance (103 F g-1 at 0.1 A g-1), superior rate capability and cyclic stability (88% capacity retention after 5000 cycles at 1 A g-1). The corresponding assembled LIC (LIC-SC2) with optimal comprehensive electrochemical performance, displayed the energy density of 83 Wh kg-1, the power density of 5718 W kg-1 and superior cyclic stability (92% energy density retention after 1000 cycles at 0.5 A g-1). It is worthwhile that the source for activated carbon is a natural and renewable one and the synthesis method is eco-friendly, which facilitate that hierarchical porous activated carbon has potential applications in the field of LIC and other energy storage systems.

  15. Micromechanical modeling of advanced materials

    SciTech Connect

    Silling, S.A.; Taylor, P.A.; Wise, J.L.; Furnish, M.D.

    1994-04-01

    Funded as a laboratory-directed research and development (LDRD) project, the work reported here focuses on the development of a computational methodology to determine the dynamic response of heterogeneous solids on the basis of their composition and microstructural morphology. Using the solid dynamics wavecode CTH, material response is simulated on a scale sufficiently fine to explicitly represent the material`s microstructure. Conducting {open_quotes}numerical experiments{close_quotes} on this scale, the authors explore the influence that the microstructure exerts on the material`s overall response. These results are used in the development of constitutive models that take into account the effects of microstructure without explicit representation of its features. Applying this methodology to a glass-reinforced plastic (GRP) composite, the authors examined the influence of various aspects of the composite`s microstructure on its response in a loading regime typical of impact and penetration. As a prerequisite to the microscale modeling effort, they conducted extensive materials testing on the constituents, S-2 glass and epoxy resin (UF-3283), obtaining the first Hugoniot and spall data for these materials. The results of this work are used in the development of constitutive models for GRP materials in transient-dynamics computer wavecodes.

  16. Shock-loading response of advanced materials

    SciTech Connect

    Gray, G.T. III

    1993-08-01

    Advanced materials, such as composites (metal, ceramic, or polymer-matrix), intermetallics, foams (metallic or polymeric-based), laminated materials, and nanostructured materials are receiving increasing attention because their properties can be custom tailored specific applications. The high-rate/impact response of advanced materials is relevant to a broad range of service environments such as the crashworthiness of civilian/military vehicles, foreign-object-damage in aerospace, and light-weight armor. Increased utilization of these material classes under dynamic loading conditions requires an understanding of the relationship between high-rate/shock-wave response as a function of microstructure if we are to develop models to predict material behavior. In this paper the issues relevant to defect generation, storage, and the underlying physical basis needed in predictive models for several advanced materials will be reviewed.

  17. Modeling Dynamic Compaction of Porous Materials with the Overstress Approach

    NASA Astrophysics Data System (ADS)

    Partom, Yehuda

    2013-06-01

    To model compaction of a porous material (PM) we need 1) an equation of state (EOS) of the PM in terms of the EOS of its matrix, and 2) a compaction law. For the EOS it is common to use Herrmann's suggestion, as in his P α model. For a compaction law it is common to use a quasi-static compaction relation obtained from 1) a mezzo-scale model (as in Carroll and Holt's spherical shell model), or from 2) quasi-static tests. Here we are interested in dynamic compaction, like in a planar impact test. In dynamic compaction, the state may change too fast for the state point to follow the quasi-static compaction curve. We therefore get an overstress situation. The state point moves out of the quasi-static compaction boundary, and only with time collapses back towards it at a certain rate. In this way the dynamic compaction event becomes rate dependent. In the paper we first write down the rate equations for dynamic compaction according to this overstress approach. We then implement these equations in a hydro-code, and run some examples. We show how the overstress rate parameter can be calibrated from tests.

  18. Calibration of thermocouple psychrometers and moisture measurements in porous materials

    NASA Astrophysics Data System (ADS)

    Guz, Łukasz; Sobczuk, Henryk; Połednik, Bernard; Guz, Ewa

    2016-07-01

    The paper presents in situ method of peltier psychrometric sensors calibration which allow to determine water potential. Water potential can be easily recalculated into moisture content of the porous material. In order to obtain correct results of water potential, each probe should be calibrated. NaCl salt solutions with molar concentration of 0.4M, 0.7M, 1.0M and 1.4M, were used for calibration which enabled to obtain osmotic potential in range: -1791 kPa to -6487 kPa. Traditionally, the value of voltage generated on thermocouples during wet-bulb temperature depression is calculated in order to determine the calibration function for psychrometric in situ sensors. In the new method of calibration, the field under psychrometric curve along with peltier cooling current and duration was taken into consideration. During calibration, different cooling currents were applied for each salt solution, i.e. 3, 5, 8 mA respectively, as well as different cooling duration for each current (from 2 to 100 sec with 2 sec step). Afterwards, the shape of each psychrometric curve was thoroughly examined and a value of field under psychrometric curve was computed. Results of experiment indicate that there is a robust correlation between field under psychrometric curve and water potential. Calibrations formulas were designated on the basis of these features.

  19. Advanced Laser Based Measurements in Porous Media Combustion

    NASA Technical Reports Server (NTRS)

    Tedder, Sarah A.

    2009-01-01

    We present measurements using dual-pump dual-broadband coherent anti-Stokes Raman scattering spectroscopy (DP-DBB-CARS) inside a porous media burner. This work continues our previous measurements in such combustion systems. The existing setup was significantly modified with the aim of providing improved data quality and data rate, reduction of interferences and additional species information. These changes are presented and discussed in detail. The CARS technique was expanded to a dual-pump dual-broadband CARS system which in principle enables acquisition of temperatures together with relative H2/N2- and O2/N2- species concentrations. Experimental complexity was reduced by the use of a modified spectrometer enabling the detection of both signals, vibrational and rotational CARS, with only one detection system.

  20. Small-angle and surface scattering from porous and fractal materials.

    SciTech Connect

    Sinha, S. K.

    1998-09-18

    We review the basic theoretical methods used to treat small-angle scattering from porous materials, treated as general two-phase systems, and also the basic experimental techniques for carrying out such experiments. We discuss the special forms of the scattering when the materials exhibit mass or surface fractal behavior, and review the results of recent experiments on several types of porous media and also SANS experiments probing the phase behavior of binary fluid mixtures or polymer solutions confined in porous materials. Finally, we discuss the analogous technique of off-specular scattering from surfaces and interfaces which is used to study surface roughness of various kinds.

  1. Analysis of ignition of a porous energetic material

    SciTech Connect

    Telengator, A.M.; Williams, F.A.; Margolis, S.B.

    1998-04-01

    A theory of ignition is presented to analyze the effect of porosity on the time to ignition of a semi-infinite porous energetic solid subjected to a constant energy flux. An asymptotic perturbation analysis, based on the smallness of the gas-to-solid density ratio and the largeness of the activation energy, is utilized to describe the inert and transition stages leading to thermal runaway. As in the classical study of a nonporous solid, the transition stage consists of three spatial regions in the limit of large activation energy: a thin reactive-diffusive layer adjacent to the exposed surface of the material where chemical effects are first felt, a somewhat thicker transient-diffusive zone, and finally an inert region where the temperature field is still governed solely by conductive heat transfer. Solutions in each region are constructed at each order with respect to the density-ratio parameter and matched to one another using asymptotic matching principles. It is found that the effects of porosity provide a leading-order reduction in the time to ignition relative to that for the nonporous problem, arising from the reduced amount of solid material that must be heated and the difference in thermal conductivities of the solid and gaseous phases. A positive correction to the leading-order ignition-delay time, however, is provided by the convective flow of gas out of the solid, which stems from the effects of thermal expansion and removes energy from the system. The latter phenomenon is absent from the corresponding calculation for the nonporous problem and produces a number of modifications at the next order in the analysis arising from the relative transport effects associated with the gas flow.

  2. Comparison of porous and nonporous materials for methane storage

    SciTech Connect

    Thallapally, Praveen K.; Kirby, Karen A.; Atwood, Jerry L.

    2007-05-10

    Sublimed, low-density p-tert-buytlcalix(4)arene absorbs methane more readily at room temperature and 1 atm pressure than do either single wall carbon nanotubes (SWNT) or a comparaitive porous metal-organic framework (MOF-1).

  3. Advanced Electrical Materials and Component Development

    NASA Technical Reports Server (NTRS)

    Schwarze, Gene E.

    2003-01-01

    The primary means to develop advanced electrical components is to develop new and improved materials for magnetic components (transformers, inductors, etc.), capacitors, and semiconductor switches and diodes. This paper will give a description and status of the internal and external research sponsored by NASA Glenn Research Center on soft magnetic materials, dielectric materials and capacitors, and high quality silicon carbide (SiC) atomically smooth substrates. The rationale for and the benefits of developing advanced electrical materials and components for the PMAD subsystem and also for the total power system will be briefly discussed.

  4. Ion beam processing of advanced electronic materials

    SciTech Connect

    Cheung, N.W.; Marwick, A.D.; Roberto, J.B.; International Business Machines Corp., Yorktown Heights, NY . Thomas J. Watson Research Center; Oak Ridge National Lab., TN )

    1989-01-01

    This report contains research programs discussed at the materials research society symposia on ion beam processing of advanced electronic materials. Major topics include: shallow implantation and solid-phase epitaxy; damage effects; focused ion beams; MeV implantation; high-dose implantation; implantation in III-V materials and multilayers; and implantation in electronic materials. Individual projects are processed separately for the data bases. (CBS)

  5. Examining porous bio-active glass as a potential osteo-odonto-keratoprosthetic skirt material.

    PubMed

    Huhtinen, Reeta; Sandeman, Susan; Rose, Susanna; Fok, Elsie; Howell, Carol; Fröberg, Linda; Moritz, Niko; Hupa, Leena; Lloyd, Andrew

    2013-05-01

    Bio-active glass has been developed for use as a bone substitute with strong osteo-inductive capacity and the ability to form strong bonds with soft and hard tissue. The ability of this material to enhance tissue in-growth suggests its potential use as a substitute for the dental laminate of an osteo-odonto-keratoprosthesis. A preliminary in vitro investigation of porous bio-active glass as an OOKP skirt material was carried out. Porous glass structures were manufactured from bio-active glasses 1-98 and 28-04 containing varying oxide formulation (1-98, 28-04) and particle size range (250-315 μm for 1-98 and 28-04a, 315-500 μm for 28-04b). Dissolution of the porous glass structure and its effect on pH was measured. Structural 2D and 3D analysis of porous structures were performed. Cell culture experiments were carried out to study keratocyte adhesion and the inflammatory response induced by the porous glass materials. The dissolution results suggested that the porous structure made out of 1-98 dissolves faster than the structures made from glass 28-04. pH experiments showed that the dissolution of the porous glass increased the pH of the surrounding solution. The cell culture results showed that keratocytes adhered onto the surface of each of the porous glass structures, but cell adhesion and spreading was greatest for the 98a bio-glass. Cytokine production by all porous glass samples was similar to that of the negative control indicating that the glasses do not induce a cytokine driven inflammatory response. Cell culture results support the potential use of synthetic porous bio-glass as an OOKP skirt material in terms of limited inflammatory potential and capacity to induce and support tissue ingrowth.

  6. Recent Advances on Luminescent Enhancement-Based Porous Silicon Biosensors.

    PubMed

    Jenie, S N Aisyiyah; Plush, Sally E; Voelcker, Nicolas H

    2016-10-01

    Luminescence-based detection paradigms have key advantages over other optical platforms such as absorbance, reflectance or interferometric based detection. However, autofluorescence, low quantum yield and lack of photostability of the fluorophore or emitting molecule are still performance-limiting factors. Recent research has shown the need for enhanced luminescence-based detection to overcome these drawbacks while at the same time improving the sensitivity, selectivity and reducing the detection limits of optical sensors and biosensors. Nanostructures have been reported to significantly improve the spectral properties of the emitting molecules. These structures offer unique electrical, optic and magnetic properties which may be used to tailor the surrounding electrical field of the emitter. Here, the main principles behind luminescence and luminescence enhancement-based detections are reviewed, with an emphasis on europium complexes as the emitting molecule. An overview of the optical porous silicon microcavity (pSiMC) as a biosensing platform and recent proof-of-concept examples on enhanced luminescence-based detection using pSiMCs are provided and discussed.

  7. Advanced Materials for Exploration Task Research Results

    NASA Technical Reports Server (NTRS)

    Cook, M. B. (Compiler); Murphy, K. L.; Schneider, T.

    2008-01-01

    The Advanced Materials for Exploration (AME) Activity in Marshall Space Flight Center s (MSFC s) Exploration Science and Technology Directorate coordinated activities from 2001 to 2006 to support in-space propulsion technologies for future missions. Working together, materials scientists and mission planners identified materials shortfalls that are limiting the performance of long-term missions. The goal of the AME project was to deliver improved materials in targeted areas to meet technology development milestones of NASA s exploration-dedicated activities. Materials research tasks were targeted in five areas: (1) Thermal management materials, (2) propulsion materials, (3) materials characterization, (4) vehicle health monitoring materials, and (5) structural materials. Selected tasks were scheduled for completion such that these new materials could be incorporated into customer development plans.

  8. Supercritical adsorption testing of porous silicon, activated carbon, and zeolite materials

    NASA Astrophysics Data System (ADS)

    Harvey, Brendan

    The supercritical adsorption of methane gas on porous silicon, activated carbon, and zeolite materials was studied. An apparatus that utilizes the volumetric adsorption measurement technique was designed and constructed to conduct the experiments. Activated carbon materials consisted of Norit RX3 Extra, Zorflex FM30K woven activated carbon cloth, and Zorflex FM10 knitted activated carbon cloth. Zeolite materials consisted of 3A, 4A, 5A, and 13X zeolites. Porous silicon materials consisted of stain etched and electrochemically etched porous films, and stain etched porous powder. All adsorption tests were conducted at room temperature (approximately 298 K) and pressures up to approximately 5 MPa. Overall, the Norit RX3 Extra granulated activated carbon produced the highest excess adsorption and effective storage capacities. Effective storage and delivery capacities of 109 and 90 stpmlml were obtained at a pressure of 3.5 MPa and a temperature of approximately 298 K.

  9. DDT modeling and shock compression experiments of porous or damaged energetic materials

    SciTech Connect

    Baer, M.R.; Anderson, M.U.; Graham, R.A.

    1994-05-01

    In this presentation, we present modeling of DDT in porous energetic materials and experimental studies of a time-resolved, shock compression of highly porous inert and reactive materials. This combined theoretical and experimental studies explore the nature of the microscale processes of consolidation, deformation and reaction which are key features of the shock response of porous or damaged energetic materials. The theoretical modeling is based on the theory of mixtures in which multiphase mixtures are treated in complete nonequilibrium allowing for internal boundary effects associated mass/momentum and energy exchange between phases, relative flow, rate-dependent compaction behavior, multistage chemistry and interphase boundary effects. Numerous studies of low-velocity impacts using a high resolution adaptive finite element method are presented which replicate experimental observations. The incorporation of this model into multi-material hydrocode analysis will be discussed to address the effects of confinement and its influence on accelerated combustion behavior. The experimental studies will focus on the use of PVDF piezoelectric polymer stress-rate gauge to precisely measure the input and propagating shock stress response of porous materials. In addition to single constituent porous materials, such as granular HMX, we have resolved shock waves in porous composite intermetallic powders that confirm a dispersive wave nature which is highly morphologically and material dependent. This document consists of viewgraphs from the poster session.

  10. Coupled hydromechanical and electromagnetic disturbances in unsaturated porous materials.

    PubMed

    Revil, A; Mahardika, H

    2013-02-01

    A theory of cross-coupled flow equations in unsaturated soils is necessary to predict (1) electroosmotic flow with application to electroremediation and agriculture, (2) the electroseismic and the seismoelectric effects to develop new geophysical methods to characterize the vadose zone, and (3) the streaming current, which can be used to investigate remotely ground water flow in unsaturated conditions in the capillary water regime. To develop such a theory, the cross-coupled generalized Darcy and Ohm constitutive equations of transport are extended to unsaturated conditions. This model accounts for inertial effects and for the polarization of porous materials. Rather than using the zeta potential, like in conventional theories for the saturated case, the key parameter used here is the quasi-static volumetric charge density of the pore space, which can be directly computed from the quasi-static permeability. The apparent permeability entering Darcy's law is also frequency dependent with a critical relaxation time that is, in turn, dependent on saturation. A decrease of saturation increases the associated relaxation frequency. The final form of the equations couples the Maxwell equations and a simplified form of two-fluid phases Biot theory accounting for water saturation. A generalized expression of the Richard equation is derived, accounting for the effect of the vibration of the skeleton during the passage of seismic waves and the electrical field. A new expression is obtained for the effective stress tensor. The model is tested against experimental data regarding the saturation and frequency dependence of the streaming potential coupling coefficient. The model is also adapted for two-phase flow conditions and a numerical application is shown for water flooding of a nonaqueous phase liquid (NAPL, oil) contaminated aquifer. Seismoelectric conversions are mostly taking place at the NAPL (oil)/water encroachment front and can be therefore used to remotely track the

  11. Coupled hydromechanical and electromagnetic disturbances in unsaturated porous materials

    PubMed Central

    Revil, A; Mahardika, H

    2013-01-01

    A theory of cross-coupled flow equations in unsaturated soils is necessary to predict (1) electroosmotic flow with application to electroremediation and agriculture, (2) the electroseismic and the seismoelectric effects to develop new geophysical methods to characterize the vadose zone, and (3) the streaming current, which can be used to investigate remotely ground water flow in unsaturated conditions in the capillary water regime. To develop such a theory, the cross-coupled generalized Darcy and Ohm constitutive equations of transport are extended to unsaturated conditions. This model accounts for inertial effects and for the polarization of porous materials. Rather than using the zeta potential, like in conventional theories for the saturated case, the key parameter used here is the quasi-static volumetric charge density of the pore space, which can be directly computed from the quasi-static permeability. The apparent permeability entering Darcy's law is also frequency dependent with a critical relaxation time that is, in turn, dependent on saturation. A decrease of saturation increases the associated relaxation frequency. The final form of the equations couples the Maxwell equations and a simplified form of two-fluid phases Biot theory accounting for water saturation. A generalized expression of the Richard equation is derived, accounting for the effect of the vibration of the skeleton during the passage of seismic waves and the electrical field. A new expression is obtained for the effective stress tensor. The model is tested against experimental data regarding the saturation and frequency dependence of the streaming potential coupling coefficient. The model is also adapted for two-phase flow conditions and a numerical application is shown for water flooding of a nonaqueous phase liquid (NAPL, oil) contaminated aquifer. Seismoelectric conversions are mostly taking place at the NAPL (oil)/water encroachment front and can be therefore used to remotely track the

  12. Attenuation of shock waves propagating through nano-structured porous materials

    NASA Astrophysics Data System (ADS)

    Al-Qananwah, Ahmad K.; Koplik, Joel; Andreopoulos, Yiannis

    2013-07-01

    Porous materials have long been known to be effective in energy absorption and shock wave attenuation. These properties make them attractive in blast mitigation strategies. Nano-structured materials have an even greater potential for blast mitigation because of their high surface-to-volume ratio, a geometric parameter which substantially attenuates shock wave propagation. A molecular dynamics approach was used to explore the effects of this remarkable property on the behavior of traveling shocks impacting on solid materials. The computational setup included a moving piston, a gas region and a target solid wall with and without a porous structure. The gas and porous solid were modeled by Lennard-Jones-like and effective atom potentials, respectively. The shock wave is resolved in space and time and its reflection from a solid wall is gradual, due to the wave's finite thickness, and entails a self-interaction as the reflected wave travels through the incoming incident wave. Cases investigated include a free standing porous structure, a porous structure attached to a wall and porous structures with graded porosity. The effects of pore shape and orientation have been also documented. The results indicate that placing a nano-porous material layer in front of the target wall reduced the stress magnitude and the energy deposited inside the solid by about 30 percent, while at the same time substantially decreasing the loading rate.

  13. Joining of advanced materials by superplastic deformation

    DOEpatents

    Goretta, Kenneth C.; Routbort, Jules L.; Gutierrez-Mora, Felipe

    2008-08-19

    A method for utilizing superplastic deformation with or without a novel joint compound that leads to the joining of advanced ceramic materials, intermetallics, and cermets. A joint formed by this approach is as strong as or stronger than the materials joined. The method does not require elaborate surface preparation or application techniques.

  14. Joining of advanced materials by superplastic deformation

    DOEpatents

    Goretta, Kenneth C.; Routbort, Jules L.; Gutierrez-Mora, Felipe

    2005-12-13

    A method for utilizing superplastic deformation with or without a novel joint compound that leads to the joining of advanced ceramic materials, intermetallics, and cermets. A joint formed by this approach is as strong as or stronger than the materials joined. The method does not require elaborate surface preparation or application techniques.

  15. Bacteria transport through porous material: Final technical report

    SciTech Connect

    Yen, T.F.

    1989-02-13

    The injection and penetration of bacteria into a reservoir is the most problematic and crucial of the steps in microbial enhanced recovery (MEOR). In the last phase of our work valuable information on bacterial transport in porous media was obtained. A great deal of progress was made to determine chemical bonding characteristics between adsorbed bacteria and the rock surfaces. In order to further enhance our knowledge of the effects of surface tensions on bacteria transport through porous media, a new approach was taken to illustrate the effect of liquid surface tension on bacterial transport through a sandpack column. Work in surface charge characterization of reservoir rock as a composite oxide system was also accomplished. In the last section of this report a mathematical model to simulate the simultaneous diffusion and growth of bacteria cells in a nutrient-enriched porous media is proposed.

  16. New Advanced Dielectric Materials for Accelerator Applications

    SciTech Connect

    Kanareykin, A.

    2010-11-04

    We present our recent results on the development and experimental testing of advanced dielectric materials that are capable of supporting the high RF electric fields generated by electron beams or pulsed high power microwaves. These materials have been optimized or specially designed for accelerator applications. The materials discussed here include low loss microwave ceramics, quartz, Chemical Vapor Deposition diamonds and nonlinear Barium Strontium Titanate based ferroelectrics.

  17. New Advanced Dielectric Materials for Accelerator Applications

    NASA Astrophysics Data System (ADS)

    Kanareykin, A.

    2010-11-01

    We present our recent results on the development and experimental testing of advanced dielectric materials that are capable of supporting the high RF electric fields generated by electron beams or pulsed high power microwaves. These materials have been optimized or specially designed for accelerator applications. The materials discussed here include low loss microwave ceramics, quartz, Chemical Vapor Deposition diamonds and nonlinear Barium Strontium Titanate based ferroelectrics.

  18. Advanced materials for aircraft engine applications.

    PubMed

    Backman, D G; Williams, J C

    1992-02-28

    A review of advances for aircraft engine structural materials and processes is presented. Improved materials, such as superalloys, and the processes for making turbine disks and blades have had a major impact on the capability of modern gas turbine engines. New structural materials, notably composites and intermetallic materials, are emerging that will eventually further enhance engine performance, reduce engine weight, and thereby enable new aircraft systems. In the future, successful aerospace manufacturers will combine product design and materials excellence with improved manufacturing methods to increase production efficiency, enhance product quality, and decrease the engine development cycle time.

  19. Advanced materials for aircraft engine applications.

    PubMed

    Backman, D G; Williams, J C

    1992-02-28

    A review of advances for aircraft engine structural materials and processes is presented. Improved materials, such as superalloys, and the processes for making turbine disks and blades have had a major impact on the capability of modern gas turbine engines. New structural materials, notably composites and intermetallic materials, are emerging that will eventually further enhance engine performance, reduce engine weight, and thereby enable new aircraft systems. In the future, successful aerospace manufacturers will combine product design and materials excellence with improved manufacturing methods to increase production efficiency, enhance product quality, and decrease the engine development cycle time. PMID:17817782

  20. Materials Requirements for Advanced Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Whitaker, Ann F.; Cook, Mary Beth; Clinton, R. G., Jr.

    2005-01-01

    NASA's mission to "reach the Moon and Mars" will be obtained only if research begins now to develop materials with expanded capabilities to reduce mass, cost and risk to the program. Current materials cannot function satisfactorily in the deep space environments and do not meet the requirements of long term space propulsion concepts for manned missions. Directed research is needed to better understand materials behavior for optimizing their processing. This research, generating a deeper understanding of material behavior, can lead to enhanced implementation of materials for future exploration vehicles. materials providing new approaches for manufacture and new options for In response to this need for more robust materials, NASA's Exploration Systems Mission Directorate (ESMD) has established a strategic research initiative dedicated to materials development supporting NASA's space propulsion needs. The Advanced Materials for Exploration (AME) element directs basic and applied research to understand material behavior and develop improved materials allowing propulsion systems to operate beyond their current limitations. This paper will discuss the approach used to direct the path of strategic research for advanced materials to ensure that the research is indeed supportive of NASA's future missions to the moon, Mars, and beyond.

  1. Advanced Materials and Processing 2010

    NASA Astrophysics Data System (ADS)

    Zhang, Yunfeng; Su, Chun Wei; Xia, Hui; Xiao, Pengfei

    2011-06-01

    Strain sensors made from MWNT/polymer nanocomposites / Gang Yin, Ning Hu and Yuan Li -- Shear band evolution and nanostructure formation in titanium by cold rolling / Dengke Yang, Peter D. Hodgson and Cuie Wen -- Biodegradable Mg-Zr-Ca alloys for bone implant materials / Yuncang Li ... [et al.] -- Hydroxyapatite synthesized from nanosized calcium carbonate via hydrothermal method / Yu-Shiang Wu, Wen-Ku Chang and Min Jou -- Modeling of the magnetization process and orthogonal fluxgate sensitivity of ferromagnetic micro-wire arrays / Fan Jie ... [et al.] -- Fabrication of silicon oxide nanowires on Ni coated silicon substrate by simple heating process / Bo Peng and Kwon-Koo Cho -- Deposition of TiOxNy thin films with various nitrogen flow rate: growth behavior and structural properties / S.-J. Cho ... [et al.] -- Observation on photoluminescence evolution in 300 KeV self-ion implanted and annealed silicon / Yu Yang ... [et al.] -- Facile synthesis of lithium niobate from a novel precursor H[symbol] / Meinan Liu ... [et al.] -- Effects of the buffer layers on the adhesion and antimicrobial properties of the amorphous ZrAlNiCuSi films / Pai-Tsung Chiang ... [et al.] -- Fabrication of ZnO nanorods by electrochemical deposition process and its photovoltaic properties / Jin-Hwa Kim ... [et al.] -- Cryogenic resistivities of NbTiAlVTaLax, CoCrFeNiCu and CoCrFeNiAl high entropy alloys / Xiao Yang and Yong Zhang -- Modeling of centrifugal force field and the effect on filling and solidification in centrifugal casting / Wenbin Sheng, Chunxue Ma and Wanli Gu -- Electrochemical properties of TiO[symbol] nanotube arrays film prepared by anodic oxidation / Young-Jin Choi ... [et al.] -- Effect of Ce additions on high temperature properties of Mg-5Sn-3Al-1Zn alloy / Byoung Soo Kang ... [et al.] -- Sono-electroless plating of Ni-Mo-P film / Atsushi Chiba, Masato Kanou and Wen-Chang Wu -- Diameter dependence of giant magneto-impedance effect in co-based melt extracted amorphous

  2. Institute for Advanced Materials at University of Louisville

    SciTech Connect

    Sunkara, Mahendra; Sumaneskara, Gamini; Starr, Thomas L; Willing, G A; Robert W, Cohn

    2009-10-29

    In this project, a university-wide, academic center has been established entitled Institute for Advanced Materials and Renewable Energy. In this institute, a comprehensive materials characterization facility has been established by co-locating several existing characterization equipment and acquiring several state of the art instrumentation such as field emission transmission electron microscope, scanning electron microscope, high resolution X-ray diffractometer, Particle Size Distribution/Zeta Potential measurement system, and Ultra-microtome for TEM specimen. In addition, a renewable energy conversion and storage research facility was also established by acquiring instrumentation such as UV-Vis absorption spectroscopy, Atomic Layer Deposition reactor, Solar light simulator, oxygen-free glove box, potentiostat/galvanostats and other miscellaneous items. The institute is staffed with three full-time staff members (one senior research technologist, a senior PhD level research scientist and a junior research scientist) to enable proper use of the techniques. About thirty faculty, fifty graduate students and several researchers access the facilities on a routine basis. Several industry R&D organizations (SudChemie, Optical Dynamics and Hexion) utilize the facility. The established Institute for Advanced Materials at UofL has three main objectives: (a) enable a focused research effort leading to the rapid discovery of new materials and processes for advancing alternate energy conversion and storage technologies; (b) enable offering of several laboratory courses on advanced materials science and engineering; and (c) develop university-industry partnerships based on the advanced materials research. The Institute's efforts were guided by an advisory board comprising eminent researchers from outside KY. Initial research efforts were focused on the discovery of new materials and processes for solar cells and Li ion battery electrodes. Initial sets of results helped PIs to

  3. Advanced Materials and Processing 2010

    NASA Astrophysics Data System (ADS)

    Zhang, Yunfeng; Su, Chun Wei; Xia, Hui; Xiao, Pengfei

    2011-06-01

    Strain sensors made from MWNT/polymer nanocomposites / Gang Yin, Ning Hu and Yuan Li -- Shear band evolution and nanostructure formation in titanium by cold rolling / Dengke Yang, Peter D. Hodgson and Cuie Wen -- Biodegradable Mg-Zr-Ca alloys for bone implant materials / Yuncang Li ... [et al.] -- Hydroxyapatite synthesized from nanosized calcium carbonate via hydrothermal method / Yu-Shiang Wu, Wen-Ku Chang and Min Jou -- Modeling of the magnetization process and orthogonal fluxgate sensitivity of ferromagnetic micro-wire arrays / Fan Jie ... [et al.] -- Fabrication of silicon oxide nanowires on Ni coated silicon substrate by simple heating process / Bo Peng and Kwon-Koo Cho -- Deposition of TiOxNy thin films with various nitrogen flow rate: growth behavior and structural properties / S.-J. Cho ... [et al.] -- Observation on photoluminescence evolution in 300 KeV self-ion implanted and annealed silicon / Yu Yang ... [et al.] -- Facile synthesis of lithium niobate from a novel precursor H[symbol] / Meinan Liu ... [et al.] -- Effects of the buffer layers on the adhesion and antimicrobial properties of the amorphous ZrAlNiCuSi films / Pai-Tsung Chiang ... [et al.] -- Fabrication of ZnO nanorods by electrochemical deposition process and its photovoltaic properties / Jin-Hwa Kim ... [et al.] -- Cryogenic resistivities of NbTiAlVTaLax, CoCrFeNiCu and CoCrFeNiAl high entropy alloys / Xiao Yang and Yong Zhang -- Modeling of centrifugal force field and the effect on filling and solidification in centrifugal casting / Wenbin Sheng, Chunxue Ma and Wanli Gu -- Electrochemical properties of TiO[symbol] nanotube arrays film prepared by anodic oxidation / Young-Jin Choi ... [et al.] -- Effect of Ce additions on high temperature properties of Mg-5Sn-3Al-1Zn alloy / Byoung Soo Kang ... [et al.] -- Sono-electroless plating of Ni-Mo-P film / Atsushi Chiba, Masato Kanou and Wen-Chang Wu -- Diameter dependence of giant magneto-impedance effect in co-based melt extracted amorphous

  4. Method for the preparation of ferrous low carbon porous material

    DOEpatents

    Miller, Curtis Jack

    2014-05-27

    A method for preparing a porous metal article using a powder metallurgy forming process is provided which eliminates the conventional steps associated with removing residual carbon. The method uses a feedstock that includes a ferrous metal powder and a polycarbonate binder. The polycarbonate binder can be removed by thermal decomposition after the metal article is formed without leaving a carbon residue.

  5. Materials performance in advanced combustion systems

    SciTech Connect

    Natesan, K.

    1992-12-01

    A number of advanced technologies are being developed to convert coal into clean fuels for use as feedstock in chemical plants and for power generation. From the standpoint of component materials, the environments created by coal conversion and combustion in these technologies and their interactions with materials are of interest. The trend in the new or advanced systems is to improve thermal efficiency and reduce the environmental impact of the process effluents. This paper discusses several systems that are under development and identifies requirements for materials application in those systems. Available data on the performance of materials in several of the environments are used to examine the performance envelopes for materials for several of the systems and to identify needs for additional work in different areas.

  6. Is Macroporosity Absolutely Required for Preliminary in Vitro Bone Biomaterial Study? A Comparison between Porous Materials and Flat Materials

    PubMed Central

    Lee, Juliana T.Y.; Chow, King L.; Wang, Kefeng; Tsang, Wai Hung

    2011-01-01

    Porous materials are highly preferred for bone tissue engineering due to space for blood vessel ingrowth, but this may introduce extra experimental variations because of the difficulty in precise control of porosity. In order to decide whether it is absolutely necessary to use porous materials in in vitro comparative osteogenesis study of materials with different chemistries, we carried out osteoinductivity study using C3H/10T1/2 cells, pluripotent mesenchymal stem cells (MSCs), on seven material types: hydroxyapatite (HA), α-tricalcium phosphate (α-TCP) and β-tricalcium phosphate (β-TCP) in both porous and dense forms and tissue culture plastic. For all materials under test, dense materials give higher alkaline phosphatase gene (Alp) expression compared with porous materials. In addition, the cell density effects on the 10T1/2 cells were assessed through alkaline phosphatase protein (ALP) enzymatic assay. The ALP expression was higher for higher initial cell plating density and this explains the greater osteoinductivity of dense materials compared with porous materials for in vitro study as porous materials would have higher surface area. On the other hand, the same trend of Alp mRNA level (HA > β-TCP > α-TCP) was observed for both porous and dense materials, validating the use of dense flat materials for comparative study of materials with different chemistries for more reliable comparison when well-defined porous materials are not available. The avoidance of porosity variation would probably facilitate more reproducible results. This study does not suggest porosity is not required for experiments related to bone regeneration application, but emphasizes that there is often a tradeoff between higher clinical relevance, and less variation in a less complex set up, which facilitates a statistically significant conclusion. Technically, we also show that the base of normalization for ALP activity may influence the conclusion and there may be ALP activity from

  7. Advanced materials for geothermal energy processes

    SciTech Connect

    Kukacka, L.E.

    1985-08-01

    The primary goal of the geothermal materials program is to ensure that the private sector development of geothermal energy resources is not constrained by the availability of technologically and economically viable materials of construction. This requires the performance of long-term high risk GHTD-sponsored materials R and D. Ongoing programs described include high temperature elastomers for dynamic sealing applications, advanced materials for lost circulation control, waste utilization and disposal, corrosion resistant elastomeric liners for well casing, and non-metallic heat exchangers. 9 refs.

  8. Study on Solidification of Phase Change Material in Fractal Porous Metal Foam

    NASA Astrophysics Data System (ADS)

    Zhang, Chengbin; Wu, Liangyu; Chen, Yongping

    2015-02-01

    The Sierpinski fractal is introduced to construct the porous metal foam. Based on this fractal description, an unsteady heat transfer model accompanied with solidification phase change in fractal porous metal foam embedded with phase change material (PCM) is developed and numerically analyzed. The heat transfer processes associated with solidification of PCM embedded in fractal structure is investigated and compared with that in single-pore structure. The results indicate that, for the solidification of phase change material in fractal porous metal foam, the PCM is dispersedly distributed in metal foam and the existence of porous metal matrix provides a fast heat flow channel both horizontally and vertically, which induces the enhancement of interstitial heat transfer between the solid matrix and PCM. The solidification performance of the PCM, which is represented by liquid fraction and solidification time, in fractal structure is superior to that in single-pore structure.

  9. Hydrogen-Bonded Organic Frameworks (HOFs): A New Class of Porous Crystalline Proton-Conducting Materials.

    PubMed

    Karmakar, Avishek; Illathvalappil, Rajith; Anothumakkool, Bihag; Sen, Arunabha; Samanta, Partha; Desai, Aamod V; Kurungot, Sreekumar; Ghosh, Sujit K

    2016-08-26

    Two porous hydrogen-bonded organic frameworks (HOFs) based on arene sulfonates and guanidinium ions are reported. As a result of the presence of ionic backbones appended with protonic source, the compounds exhibit ultra-high proton conduction values (σ) 0.75× 10(-2)  S cm(-1) and 1.8×10(-2)  S cm(-1) under humidified conditions. Also, they have very low activation energy values and the highest proton conductivity at ambient conditions (low humidity and at moderate temperature) among porous crystalline materials, such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs). These values are not only comparable to the conventionally used proton exchange membranes, such as Nafion used in fuel cell technologies, but is also the highest value reported in organic-based porous architectures. Notably, this report inaugurates the usage of crystalline hydrogen-bonded porous organic frameworks as solid-state proton conducting materials. PMID:27464784

  10. An Overview of Recent Development in Composite Catalysts from Porous Materials for Various Reactions and Processes

    PubMed Central

    Xie, Zaiku; Liu, Zhicheng; Wang, Yangdong; Yang, Qihua; Xu, Longya; Ding, Weiping

    2010-01-01

    Catalysts are important to the chemical industry and environmental remediation due to their effective conversion of one chemical into another. Among them, composite catalysts have attracted continuous attention during the past decades. Nowadays, composite catalysts are being used more and more to meet the practical catalytic performance requirements in the chemical industry of high activity, high selectivity and good stability. In this paper, we reviewed our recent work on development of composite catalysts, mainly focusing on the composite catalysts obtained from porous materials such as zeolites, mesoporous materials, carbon nanotubes (CNT), etc. Six types of porous composite catalysts are discussed, including amorphous oxide modified zeolite composite catalysts, zeolite composites prepared by co-crystallization or overgrowth, hierarchical porous catalysts, host-guest porous composites, inorganic and organic mesoporous composite catalysts, and polymer/CNT composite catalysts. PMID:20559508

  11. An overview of recent development in composite catalysts from porous materials for various reactions and processes.

    PubMed

    Xie, Zaiku; Liu, Zhicheng; Wang, Yangdong; Yang, Qihua; Xu, Longya; Ding, Weiping

    2010-01-01

    Catalysts are important to the chemical industry and environmental remediation due to their effective conversion of one chemical into another. Among them, composite catalysts have attracted continuous attention during the past decades. Nowadays, composite catalysts are being used more and more to meet the practical catalytic performance requirements in the chemical industry of high activity, high selectivity and good stability. In this paper, we reviewed our recent work on development of composite catalysts, mainly focusing on the composite catalysts obtained from porous materials such as zeolites, mesoporous materials, carbon nanotubes (CNT), etc. Six types of porous composite catalysts are discussed, including amorphous oxide modified zeolite composite catalysts, zeolite composites prepared by co-crystallization or overgrowth, hierarchical porous catalysts, host-guest porous composites, inorganic and organic mesoporous composite catalysts, and polymer/CNT composite catalysts. PMID:20559508

  12. Advanced composite materials: a strong growth industry

    SciTech Connect

    Lees, J.K.

    1987-01-01

    Advanced composites represent a material form that will see significant growth in structural applications. The authors notes that Du Pont sees a broad opportunity for these materials and proceeds to review reasons for the company's optimism as well as their approach to this technology. Substitution of composites for metals is shown graphically since 1960 and projected to 2025. Price reductions vs. steel of five materials also shown graphically since 1970 and projected to 1990. Today, use of advanced composites is primarily when high performance, is required, e.g., aerospace and sporting goods. The author sees a shift into higher-volume applications in the next 15 years, primarily the automotive industry. Finally, as the next century approaches, the author sees a possible capture of 50% of the structure-materials market, mostly in lightweight bridging structures and the top portion of large high-rise structures.

  13. Advanced materials from natural materials: synthesis of aligned carbon nanotubes on wollastonites.

    PubMed

    Zhao, Meng-Qiang; Zhang, Qiang; Huang, Jia-Qi; Nie, Jing-Qi; Wei, Fei

    2010-04-26

    The growth of carbon nanotubes (CNTs) on natural materials is a low-cost, environmentally benign, and materials-saving method for the large-scale production of CNTs. Directly building 3D CNT architectures on natural materials is a key issue for obtaining advanced materials with high added value. We report the fabrication of aligned CNT arrays on fibrous natural wollastonite. Strongly dispersed iron particles with small sizes were produced on a planar surface of soaked fibrous wollastonite by a reduction process. These particles then catalyzed the decomposition of ethylene, leading to the synchronous growth of CNTs to form leaf- and brush-like wollastonite/CNT hybrids. The as-obtained hybrids could be further transformed into porous SiO(2)/CNT hybrids by reaction with hydrochloric acid. Further treatment with hydrofluoric acid resulted in aligned CNT arrays, with purities as high as 98.7 %. The presented work is very promising for the fabrication of advanced materials with unique structures and properties that can be used as fillers, catalyst supports, or energy-absorbing materials. PMID:20183856

  14. Advanced materials from natural materials: synthesis of aligned carbon nanotubes on wollastonites.

    PubMed

    Zhao, Meng-Qiang; Zhang, Qiang; Huang, Jia-Qi; Nie, Jing-Qi; Wei, Fei

    2010-04-26

    The growth of carbon nanotubes (CNTs) on natural materials is a low-cost, environmentally benign, and materials-saving method for the large-scale production of CNTs. Directly building 3D CNT architectures on natural materials is a key issue for obtaining advanced materials with high added value. We report the fabrication of aligned CNT arrays on fibrous natural wollastonite. Strongly dispersed iron particles with small sizes were produced on a planar surface of soaked fibrous wollastonite by a reduction process. These particles then catalyzed the decomposition of ethylene, leading to the synchronous growth of CNTs to form leaf- and brush-like wollastonite/CNT hybrids. The as-obtained hybrids could be further transformed into porous SiO(2)/CNT hybrids by reaction with hydrochloric acid. Further treatment with hydrofluoric acid resulted in aligned CNT arrays, with purities as high as 98.7 %. The presented work is very promising for the fabrication of advanced materials with unique structures and properties that can be used as fillers, catalyst supports, or energy-absorbing materials.

  15. Sound propagation in and low frequency noise absorption by helium-filled porous material.

    PubMed

    Choy, Y S; Huang, Lixi; Wang, Chunqi

    2009-12-01

    Low-frequency noise is difficult to deal with by traditional porous material due to its inherent high acoustic impedance. This study seeks to extend the effective range of sound absorption to lower frequencies by filling a low density gas, such as helium, in the porous material. Compared with conventional air-filled absorption material, the helium-filled porous material has a much reduced characteristic impedance; hence, a good impedance matching with pure air becomes more feasible at low frequencies. The acoustic properties of a series of helium-filled porous materials are investigated with a specially designed test rig. The characteristic of the sound propagation in a helium-filled porous material is established and validated experimentally. Based on the measured acoustic properties, the sound absorption performance of a helium-filled absorber (HA) of finite thickness is studied numerically as well as experimentally. For a random incidence field, the HA is found to perform much better than the air-filled absorber at low frequencies. The main advantage of HA lies in the middle range of oblique incidence angles where wave refraction in the absorber enhances sound absorption. The advantage of HA as duct lining is demonstrated both numerically and experimentally.

  16. Fabrication of porous materials (metal, metal oxide and semiconductor) through an aerosol-assisted route

    NASA Astrophysics Data System (ADS)

    Sohn, Hiesang

    Porous materials have gained attraction owing to their vast applications in catalysts, sensors, energy storage devices, bio-devices and other areas. To date, various porous materials were synthesized through soft and hard templating approaches. However, a general synthesis method for porous non-oxide materials, metal alloys and semiconductors with tunable structure, composition and morphology has not been developed yet. To address this challenge, this thesis presents an aerosol method towards the synthesis of such materials and their applications for catalysis, hydrogen storage, Li-batteries and photo-catalysis. The first part of this thesis presents the synthesis of porous metals, metal oxides, and semiconductors with controlled pore structure, crystalline structure and morphology. In these synthesis processes, metal salts and organic ligands were employed as precursors to create porous metal-carbon frameworks. During the aerosol process, primary metal clusters and nanoparticles were formed, which were coagulated/ aggregated forming the porous particles. Various porous particles, such as those of metals (e.g., Ni, Pt, Co, Fe, and Ni xPt(1-x)), metal oxides (e.g., Fe3O4 and SnO2) and semiconductors (e.g., CdS, CuInS2, CuInS 2x-ZnS(1-x), and CuInS2x-TiO2(1-x)) were synthesized. The morphology, porous structure and crystalline structure of the particles were regulated through both templating and non-templating methods. The second part of this thesis explores the applications of these materials, including propylene hydrogenation and H2 uptake capacity of porous Ni, NiPt alloys and Ni-Pt composites, Li-storage of Fe3O4 and SnO2, photodegradation of CuInS2-based semiconductors. The effects of morphology, compositions, and porous structure on the device performance were systematically investigated. Overall, this dissertation work unveiled a simple synthesis approach for porous particles of metals, metal alloys, metal oxides, and semiconductors with controlled

  17. Materials as additives for advanced lubrication

    DOEpatents

    Pol, Vilas G.; Thackeray, Michael M.; Mistry, Kuldeep; Erdemir, Ali

    2016-09-13

    This invention relates to carbon-based materials as anti-friction and anti-wear additives for advanced lubrication purposes. The materials comprise carbon nanotubes suspended in a liquid hydrocarbon carrier. Optionally, the compositions further comprise a surfactant (e.g., to aid in dispersion of the carbon particles). Specifically, the novel lubricants have the ability to significantly lower friction and wear, which translates into improved fuel economies and longer durability of mechanical devices and engines.

  18. Highly Porous Wood Based Carbon Materials for Supercapacitors

    NASA Astrophysics Data System (ADS)

    Volperts, A.; Dobele, G.; Zhurinsh, A.; Vervikishko, D.; Shkolnikov, E.; Ozolinsh, J.; Mironova-Ulmane, N.; Sildos, I.

    2015-03-01

    Wood based activated carbons synthesized by two-stage thermocatalytical synthesis with NaOH activator were studied and used as supercapacitor electrodes (sulphuric acid electrolyte). Porous structure and electrochemical properties of carbons vs synthesis conditions were assessed. It was found that there are correlations between carbons synthesis variables, their porosity and supercapacitors functional characteristics. At the temperature 600°C and activator/precursor ratio 1.25 porosity decreased, however energy capacitance of supercapacitor increased calculating on elementary cell mass.

  19. Advancing Material Models for Automotive Forming Simulations

    NASA Astrophysics Data System (ADS)

    Vegter, H.; An, Y.; ten Horn, C. H. L. J.; Atzema, E. H.; Roelofsen, M. E.

    2005-08-01

    Simulations in automotive industry need more advanced material models to achieve highly reliable forming and springback predictions. Conventional material models implemented in the FEM-simulation models are not capable to describe the plastic material behaviour during monotonic strain paths with sufficient accuracy. Recently, ESI and Corus co-operate on the implementation of an advanced material model in the FEM-code PAMSTAMP 2G. This applies to the strain hardening model, the influence of strain rate, and the description of the yield locus in these models. A subsequent challenge is the description of the material after a change of strain path. The use of advanced high strength steels in the automotive industry requires a description of plastic material behaviour of multiphase steels. The simplest variant is dual phase steel consisting of a ferritic and a martensitic phase. Multiphase materials also contain a bainitic phase in addition to the ferritic and martensitic phase. More physical descriptions of strain hardening than simple fitted Ludwik/Nadai curves are necessary. Methods to predict plastic behaviour of single-phase materials use a simple dislocation interaction model based on the formed cells structures only. At Corus, a new method is proposed to predict plastic behaviour of multiphase materials have to take hard phases into account, which deform less easily. The resulting deformation gradients create geometrically necessary dislocations. Additional micro-structural information such as morphology and size of hard phase particles or grains is necessary to derive the strain hardening models for this type of materials. Measurements available from the Numisheet benchmarks allow these models to be validated. At Corus, additional measured values are available from cross-die tests. This laboratory test can attain critical deformations by large variations in blank size and processing conditions. The tests are a powerful tool in optimising forming simulations

  20. Property Data Summaries for Advanced Materials

    National Institute of Standards and Technology Data Gateway

    SRD 150 NIST Property Data Summaries for Advanced Materials (Web, free access)   Property Data Summaries are topical collections of property values derived from surveys of published data. Thermal, mechanical, structural, and chemical properties are included in the collections.

  1. Advanced experimental upscaling of flow and transport in porous media

    NASA Astrophysics Data System (ADS)

    Englert, A.; Musch, T.; Gevers, M.; Gebhardt, P.; Groth, S.; Kersting, R.; Goekpinar, T.

    2013-12-01

    sediment cubes and sediment bodies consisting of assembled sediment cubes. Our ongoing experiments focus on advancing the characterization of transport in both single sediment cubes and the sandbox model. Thereto, we developed a new electrical conductivity sensor system. The latter includes 13 electrodes which allow for high resolution salt concentration measurements during salt tracer tests: ensemble breakthrough measurements in the well mixed inflow and outflow chambers of the cubic Darcy cell and the sandbox model and local measurements in the center of each sediment cube. To prevent immediate contact between the sediment and the electrodes, the latter are embedded in cubic wire-mesh cages, of which the length of the edges are 1 cm. Combined analysis of local and ensemble breakthrough curves will allow not only upscaling of transport, but also understanding of the relation between a specific feature in the spatial distribution of the hydraulic conductivity and the transport process.

  2. Advanced Electrical Materials and Components Being Developed

    NASA Technical Reports Server (NTRS)

    Schwarze, Gene E.

    2004-01-01

    All aerospace systems require power management and distribution (PMAD) between the energy and power source and the loads. The PMAD subsystem can be broadly described as the conditioning and control of unregulated power from the energy source and its transmission to a power bus for distribution to the intended loads. All power and control circuits for PMAD require electrical components for switching, energy storage, voltage-to-current transformation, filtering, regulation, protection, and isolation. Advanced electrical materials and component development technology is a key technology to increasing the power density, efficiency, reliability, and operating temperature of the PMAD. The primary means to develop advanced electrical components is to develop new and/or significantly improved electronic materials for capacitors, magnetic components, and semiconductor switches and diodes. The next important step is to develop the processing techniques to fabricate electrical and electronic components that exceed the specifications of presently available state-of-the-art components. The NASA Glenn Research Center's advanced electrical materials and component development technology task is focused on the following three areas: 1) New and/or improved dielectric materials for the development of power capacitors with increased capacitance volumetric efficiency, energy density, and operating temperature; 2) New and/or improved high-frequency, high-temperature soft magnetic materials for the development of transformers and inductors with increased power density, energy density, electrical efficiency, and operating temperature; 3) Packaged high-temperature, high-power density, high-voltage, and low-loss SiC diodes and switches.

  3. Advanced Industrial Materials (AIM) fellowship program

    SciTech Connect

    McCleary, D.D.

    1997-04-01

    The Advanced Industrial Materials (AIM) Program administers a Graduate Fellowship Program focused toward helping students who are currently under represented in the nation`s pool of scientists and engineers, enter and complete advanced degree programs. The objectives of the program are to: (1) establish and maintain cooperative linkages between DOE and professors at universities with graduate programs leading toward degrees or with degree options in Materials Science, Materials Engineering, Metallurgical Engineering, and Ceramic Engineering, the disciplines most closely related to the AIM Program at Oak Ridge National Laboratory (ORNL); (2) strengthen the capabilities and increase the level of participation of currently under represented groups in master`s degree programs, and (3) offer graduate students an opportunity for practical research experience related to their thesis topic through the three-month research assignment or practicum at ORNL. The program is administered by the Oak Ridge Institute for Science and Education (ORISE).

  4. Characterisation of pore structures in nanoporous materials for advanced bionanotechnology.

    PubMed

    Heo, K; Yoon, J; Jin, K S; Jin, S; Ree, M

    2006-08-01

    Porous materials are potential candidates for applications in various fields, such as bionanotechnology, gas separation, catalysts and micro-electronics. In particular, their applications in bionanotechnology include biosensors, biomedical implants and microdevices, biosupporters, bio-encapsules, biomolecule separations and biomedical therapy. All these bionanotechnology applications utilise the shape, size and size distribution of pores in porous materials. Therefore the controlled creation of pores with desired shape, size and size distribution is most important in the development of nanoporous materials. Accordingly, the accurate evaluation of pore structure is necessary in the development of nanoporous materials and their applications. This article reviews recent developments in analytical techniques to characterise the pore structures of nanoporous materials.

  5. Strengthening of porous matrix materials with evaporation/condensation sintering for composite materials applications

    NASA Astrophysics Data System (ADS)

    Haslam, Jeffery John

    1998-12-01

    The need for improved fuel economy and reduced environmental emissions from power turbines has prompted the development of high temperature fiber composite materials. One use of these materials is for liners of the hot combustion regions of jet engines and land based power turbines. Stability of the composite materials against oxidative damage during long term use at high temperatures has motivated recent research into fiber composite materials composed entirely of oxide ceramics. All-oxide fiber reinforced composites containing porous, strongly bonded matrices have become of interest. The porosity provides for crack deflection along the fibers to prevent catastrophic failure of the fiber reinforcements. A new application of a processing method that produces evaporation/condensation sintering was employed to prevent shrinkage of the matrix. This processing method and the properties of the matrix, fibers, and composite were evaluated in this work. Producing a matrix without shrinkage is important to prevent undesirable crack-like voids from forming in the matrix. These voids are caused by constraint against shrinkage by the fiber reinforcements. Dry hydrogen chloride gas produced a reactive gas atmosphere that was used to sinter the zirconia particles with minimal shrinkage because the gas promotes evaporation/condensation sintering with zirconia. Sintering of samples that did not contain fiber reinforcements was studied to evaluate the properties of the matrix material. The sintering of monoclinic, tetragonal, and cubic zirconias in the reactive gas atmosphere was compared. Additions of mullite (which did not sinter significantly at processing temperatures) further reduced the shrinkage. The effects of the processing conditions on the sintering shrinkage, microstructure development, and mechanical properties were studied. Cubic and monoclinic zirconia coarsened significantly in the HCl gas sintering atmosphere. The coarsening of the particles during the sintering

  6. Porous hollow carbon spheres for electrode material of supercapacitors and support material of dendritic Pt electrocatalyst

    NASA Astrophysics Data System (ADS)

    Fan, Yang; Liu, Pei-Fang; Huang, Zhong-Yuan; Jiang, Tong-Wu; Yao, Kai-Li; Han, Ran

    2015-04-01

    Porous hollow carbon spheres (PHCSs) are prepared through hydrothermal carbonization of alginic acid and subsequent chemical activation by KOH. The porosity of the alginic acid derived PHCSs can be finely modulated by varying activation temperature in the range of 600-900 °C. The PHCSs activated at 900 °C possess the largest specific surface area (2421 m2 g-1), well-balanced micro- and mesoporosity, as well as high content of oxygen-containing functional groups. As the electrode material for supercapacitors, the PHCSs exhibit superior capacitive performance with specific capacitance of 314 F g-1 at current density of 1 A g-1. Pt nanodendrites supported on the PHCSs are synthesized by polyol reduction method which exhibit high electrocatalytic activity towards methanol oxidation reaction (MOR). Moreover, CO-poisoning tolerance of the Pt nanodendrites is greatly enhanced owing to the surface chemical property of the PHCSs support.

  7. Template-assisted formation of porous vanadium oxide as high performance cathode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Su, Yanhui; Pan, Anqiang; Wang, Yaping; Huang, Jiwu; Nie, Zhiwei; An, Xinxin; Liang, Shuquan

    2015-11-01

    Similar to carbonaceous materials, porous metal oxides have attracted wide attention in energy storage and conversion systems because of their structural advantages, including high activity and electrolyte accessibility. In this work, we report the novel preparation of porous vanadium pentoxide (V2O5) as high performance cathode material for lithium ion batteries. Ketjen black (KB), a porous carbon material, has been employed as hard templates to host precursor species in their porous structures. The porous V2O5 electrode material is prepared after removing the KB carbon framework by calcinating the composites in air. As cathode materials for lithium ion batteries, the porous V2O5 electrodes exhibit high capacity, good cycling stability and rate capability. An initial discharge capacity of 141.1 mA h g-1 is delivered at a current density of 100 mAg-1, very close to the theoretical capacity of 147 mA h g-1.

  8. Structural materials challenges for advanced reactor systems

    NASA Astrophysics Data System (ADS)

    Yvon, P.; Carré, F.

    2009-03-01

    Key technologies for advanced nuclear systems encompass high temperature structural materials, fast neutron resistant core materials, and specific reactor and power conversion technologies (intermediate heat exchanger, turbo-machinery, high temperature electrolytic or thermo-chemical water splitting processes, etc.). The main requirements for the materials to be used in these reactor systems are dimensional stability under irradiation, whether under stress (irradiation creep or relaxation) or without stress (swelling, growth), an acceptable evolution under ageing of the mechanical properties (tensile strength, ductility, creep resistance, fracture toughness, resilience) and a good behavior in corrosive environments (reactor coolant or process fluid). Other criteria for the materials are their cost to fabricate and to assemble, and their composition could be optimized in order for instance to present low-activation (or rapid desactivation) features which facilitate maintenance and disposal. These requirements have to be met under normal operating conditions, as well as in incidental and accidental conditions. These challenging requirements imply that in most cases, the use of conventional nuclear materials is excluded, even after optimization and a new range of materials has to be developed and qualified for nuclear use. This paper gives a brief overview of various materials that are essential to establish advanced systems feasibility and performance for in pile and out of pile applications, such as ferritic/martensitic steels (9-12% Cr), nickel based alloys (Haynes 230, Inconel 617, etc.), oxide dispersion strengthened ferritic/martensitic steels, and ceramics (SiC, TiC, etc.). This article gives also an insight into the various natures of R&D needed on advanced materials, including fundamental research to investigate basic physical and chemical phenomena occurring in normal and accidental operating conditions, lab-scale tests to characterize candidate materials

  9. Tailoring of the porous structure of soft emulsion-templated polymer materials.

    PubMed

    Kovalenko, Artem; Zimny, Kévin; Mascaro, Benoit; Brunet, Thomas; Mondain-Monval, Olivier

    2016-06-21

    This paper discusses the formation of soft porous materials obtained by the polymerization of inverse water-in-silicone (polydimethylsiloxane, PDMS) emulsions. We show that the initial state of the emulsion has a strong impact on the porous structure and properties of the final material. We show that using a surfactant with different solubilities in the emulsion continuous phase (PDMS), it is possible to tune the interaction between emulsion droplets, which leads to materials with either interconnected or isolated pores. These two systems present completely different behavior upon drying, which results in macroporous air-filled materials in the interconnected case and in a collapsed material with low porosity in the second case. Finally, we compare the mechanical and acoustical properties of these two types of bulk polymer monoliths. We also describe the formation of micrometric polymer particles (beads) in these two cases. We show that materials with an interconnected macroporous structure have low mechanical moduli and low sound speed, and are suitable for acoustic applications. The mechanical and acoustical properties of the materials with a collapsed porous structure are similar to those of non-porous silicone, which makes them acoustically inactive. PMID:27195990

  10. Systems and strippable coatings for decontaminating structures that include porous material

    DOEpatents

    Fox, Robert V.; Avci, Recep; Groenewold, Gary S.

    2011-12-06

    Methods of removing contaminant matter from porous materials include applying a polymer material to a contaminated surface, irradiating the contaminated surface to cause redistribution of contaminant matter, and removing at least a portion of the polymer material from the surface. Systems for decontaminating a contaminated structure comprising porous material include a radiation device configured to emit electromagnetic radiation toward a surface of a structure, and at least one spray device configured to apply a capture material onto the surface of the structure. Polymer materials that can be used in such methods and systems include polyphosphazine-based polymer materials having polyphosphazine backbone segments and side chain groups that include selected functional groups. The selected functional groups may include iminos, oximes, carboxylates, sulfonates, .beta.-diketones, phosphine sulfides, phosphates, phosphites, phosphonates, phosphinates, phosphine oxides, monothio phosphinic acids, and dithio phosphinic acids.

  11. Sound Transmission Through Multi-Panel Structures Lined with Elastic Porous Materials

    NASA Astrophysics Data System (ADS)

    Bolton, J. S.; Shiau, N.-M.; Kang, Y. J.

    1996-04-01

    Theory and measurements related to sound transmission through double panels lined with elastic porous media are presented. The information has application to the design of noise control barriers and to the optimization of aircraft fuselage transmission loss, for example. The major difference between the work described here and earlier research in this field relates to the treatment of the porous material that is used to line the cavity between the two panels of the double panel structure. Here we have used the porous material theory proposed by Biot since it takes explicit account of all the wave types known to propagate in elastic porous materials. As a result, it is possible to use the theory presented here to calculate the transmission loss of lined double panels at arbitrary angles of incidence; results calculated over a range of incidence angles may then be combined to yield the random incidence transmission loss. In this paper, the equations governing wave propagation in an elastic porous material are first considered briefly and then the general forms for the stresses and displacements within the porous material are given. Those solutions are expressed in terms of a number of constants that can be determined by application of appropriate boundary conditions. The boundary conditions required to model double panels having linings that are either directly attached to the facing panels or separated?!from them by air gaps are presented and discussed. Measurements of the random incidence transmission loss of aluminium double-panel structures lined with polyurethane foam are presented and have been found to be in good agreement with theoretical predictions. Both the theoretical predictions and the measured results have shown that the method by which an elastic porous lining material is attached to the facing panels can have a profound influence on the transmission loss of the panel system. It has been found, for example, that treatments in which the lining material

  12. Advanced fiber/matrix material systems

    NASA Technical Reports Server (NTRS)

    Hartness, J. Timothy

    1991-01-01

    Work completed in Phase 1 of the NASA Advanced Composite Technology program is discussed. Two towpreg forms (commingled yarns and fused powder towpregs) are being characterized under the program. These towpregs will be used to evaluate textile fabrication technologies for advanced aircraft composite structures. The unique characteristic of both of these material forms is that both fiber and matrix resin are handled in a single operation such as weaving, braiding, or fiber placement. The evaluation of both commingled and fused powder towpreg is described. Various polymer materials are considered for both subsonic and supersonic applications. Polymers initially being evaluated include thermoplastic polyimides such as Larc-TPI and New-TPI, thermoplastics such as PEEK and PEKEKK as well as some toughened crosslinked polyimides. Preliminary mechanical properties as well as tow handling are evaluated.

  13. Task 8.9 - Advanced ceramic materials

    SciTech Connect

    1997-06-30

    Advanced ceramic materials such as Continuous Fiber Reinforced Ceramic Matrix Composites (CFCCs) have had promising results on the companion program entitled ``Ceramic Stationary Gas Turbine`` (CSGT). In particular, CFCCs have outperformed monolithic tiles in structural integrity as a combustor liner. Also, CFCCs have provided the higher temperature operation and improved emissions performance that is required for the ATS combustor. The demonstrated advantages on CSGT justified work to explore the use of advanced ceramic composite materials in other gas turbine components. Sub-tasks include development of a practical, cost effective component fabrication process, development of finite element stress analysis to assure 30,000 hours of component life, and fabrication of a demonstration article.

  14. Potential of Lattice Boltzmann Method to Determine the Ohmic Resistance in Porous Materials

    NASA Astrophysics Data System (ADS)

    Espinoza-Andaluz, Mayken; Andersson, Martin; Sundén, Bengt

    2016-08-01

    The lattice Boltzmann method (LBM) is a suitable tool for solving transport phenomena that occur in gas- and liquid phases at different length scales, especially when complex geometries such as porous media are involved. However, investigations about applications of LBM in the solid electrical conducting material have not been carried out yet. Since in fuel cells (FCs) the multifunctional layers play an important role during the energy conversion process, and such layers consist of porous material, the ohmic resistance of porous materials represents a crucial characteristic to be studied to predict the internal ohmic losses. The purpose of this paper is to show the feasibility of LBM to determine the ohmic resistance of electrical conducting materials whose dimensions are modified considering the crosssectional area and length. Characteristics, limitations and recommendations of LBM applied to solid electrical conducting materials calculating the ohmic resistance are presented considering the coupling of the methodology with the Ohm's Law. Additionally, the behavior of the ohmic resistance for a given porous material is presented.

  15. Advanced laser processing of glass materials

    NASA Astrophysics Data System (ADS)

    Sugioka, Koji; Obata, Kotaro; Cheng, Ya; Midorikawa, Katsumi

    2003-09-01

    Three kinds of advanced technologies using lasers for glass microprocessing are reviewed. Simultaneous irradiation of vacuum ultraviolet (VUV) laser beam, which possesses extremely small laser fluence, with ultraviolet (UV) laser achieves enhanced high surface and edge quality ablation in fused silica and other hard materials with little debris deposition as well as high-speed and high-efficiency refractive index modification of fused silica (VUV-UV multiwavelength excitation processing). Metal plasma generated by the laser beam effectively assists high-quality ablation of transparent materials, resulting in surface microstructuring, high-speed holes drilling, crack-free marking, color marking, painting and metal interconnection for the various kinds of glass materials (laser-induced plasma-assisted ablation (LIPAA)). In the meanwhile, a nature of multiphoton absorption of femtosecond laser by transparent materials realizes fabrication of true three-dimensional microstructures embedded in photosensitive glass.

  16. Advanced materials for space nuclear power systems

    SciTech Connect

    Titran, R.H.; Grobstein, T.L. . Lewis Research Center); Ellis, D.L. )

    1991-01-01

    Research on monolithic refractory metal alloys and on metal matrix composites is being conducted at the NASA Lewis Research Center, Cleveland, Ohio, in support of advanced space power systems. The overall philosophy of the research is to develop and characterize new high-temperature power conversion and radiator materials and to provide spacecraft designers with material selection options and design information. Research on three candidate materials (carbide strengthened niobium alloy PWC-11 for fuel cladding, graphite fiber reinforced copper matrix composites (Gr/Cu) for heat rejection fins, and tungsten fiber reinforced niobium matrix composites (W/NB) for fuel containment and structural supports) considered for space power system applications is discussed. Each of these types of materials offers unique advantages for space power applications.

  17. Advanced Thermoelectric Materials for Radioisotope Thermoelectric Generators

    NASA Technical Reports Server (NTRS)

    Caillat, Thierry; Hunag, C.-K.; Cheng, S.; Chi, S. C.; Gogna, P.; Paik, J.; Ravi, V.; Firdosy, S.; Ewell, R.

    2008-01-01

    This slide presentation reviews the progress and processes involved in creating new and advanced thermoelectric materials to be used in the design of new radioiootope thermoelectric generators (RTGs). In a program with Department of Energy, NASA is working to develop the next generation of RTGs, that will provide significant benefits for deep space missions that NASA will perform. These RTG's are planned to be capable of delivering up to 17% system efficiency and over 12 W/kg specific power. The thermoelectric materials being developed are an important step in this process.

  18. Library of Advanced Materials for Engineering : LAME.

    SciTech Connect

    Hammerand, Daniel Carl; Scherzinger, William Mark

    2007-08-01

    Constitutive modeling is an important aspect of computational solid mechanics. Sandia National Laboratories has always had a considerable effort in the development of constitutive models for complex material behavior. However, for this development to be of use the models need to be implemented in our solid mechanics application codes. In support of this important role, the Library of Advanced Materials for Engineering (LAME) has been developed in Engineering Sciences. The library allows for simple implementation of constitutive models by model developers and access to these models by application codes. The library is written in C++ and has a very simple object oriented programming structure. This report summarizes the current status of LAME.

  19. Advanced Ceramic Materials for Future Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Misra, Ajay

    2015-01-01

    With growing trend toward higher temperature capabilities, lightweight, and multifunctionality, significant advances in ceramic matrix composites (CMCs) will be required for future aerospace applications. The presentation will provide an overview of material requirements for future aerospace missions, and the role of ceramics and CMCs in meeting those requirements. Aerospace applications will include gas turbine engines, aircraft structure, hypersonic and access to space vehicles, space power and propulsion, and space communication.

  20. Porous and Microporous Honeycomb Composites as Potential Boundary-Layer Bleed Materials

    NASA Technical Reports Server (NTRS)

    Davis, D. O.; Willis, B. P.; Schoenenberger, M.

    1997-01-01

    Results of an experimental investigation are presented in which the use of porous and microporous honeycomb composite materials is evaluated as an alternate to perforated solid plates for boundary-layer bleed in supersonic aircraft inlets. The terms "porous" and "microporous," respectively, refer to bleed orifice diameters roughly equal to and much less than the displacement thickness of the approach boundary-layer. A Baseline porous solid plate, two porous honeycomb, and three microporous honeycomb configurations are evaluated. The performance of the plates is characterized by the flow coefficient and relative change in boundary-layer profile parameters across the bleed region. The tests were conducted at Mach numbers of 1.27 and 1.98. The results show the porous honeycomb is not as efficient at removing mass compared to the baseline. The microporous plates were about equal to the baseline with one plate demonstrating a significantly higher efficiency. The microporous plates produced significantly fuller boundary-layer profiles downstream of the bleed region for a given mass flow removal rate than either the baseline or the porous honeycomb plates.

  1. Laser-induced growth of nanocrystals embedded in porous materials

    PubMed Central

    2013-01-01

    Space localization of the linear and nonlinear optical properties in a transparent medium at the submicron scale is still a challenge to yield the future generation of photonic devices. Laser irradiation techniques have always been thought to structure the matter at the nanometer scale, but combining them with doping methods made it possible to generate local growth of several types of nanocrystals in different kinds of silicate matrices. This paper summarizes the most recent works developed in our group, where the investigated nanoparticles are either made of metal (gold) or chalcogenide semiconductors (CdS, PbS), grown in precursor-impregnated porous xerogels under different laser irradiations. This review is associated to new results on silver nanocrystals in the same kind of matrices. It is shown that, depending on the employed laser, the particles can be formed near the sample surface or deep inside the silica matrix. Photothermal and/or photochemical mechanisms may be invoked to explain the nanoparticle growth, depending on the laser, precursor, and matrix. One striking result is that metal salt reduction, necessary to the production of the corresponding nanoparticles, can efficiently occur due to the thermal wrenching of electrons from the matrix itself or due to multiphoton absorption of the laser light by a reducer additive in femtosecond regime. Very localized semiconductor quantum dots could also be generated using ultrashort pulses, but while PbS nanoparticles grow faster than CdS particles due to one-photon absorption, this better efficiency is counterbalanced by a sensitivity to oxidation. In most cases where the reaction efficiency is high, particles larger than the pores have been obtained, showing that a fast diffusion of the species through the interconnected porosity can modify the matrix itself. Based on our experience in these techniques, we compare several examples of laser-induced nanocrystal growth in porous silica xerogels, which allows

  2. Laser-induced growth of nanocrystals embedded in porous materials

    NASA Astrophysics Data System (ADS)

    Capoen, Bruno; Chahadih, Abdallah; El Hamzaoui, Hicham; Cristini, Odile; Bouazaoui, Mohamed

    2013-06-01

    Space localization of the linear and nonlinear optical properties in a transparent medium at the submicron scale is still a challenge to yield the future generation of photonic devices. Laser irradiation techniques have always been thought to structure the matter at the nanometer scale, but combining them with doping methods made it possible to generate local growth of several types of nanocrystals in different kinds of silicate matrices. This paper summarizes the most recent works developed in our group, where the investigated nanoparticles are either made of metal (gold) or chalcogenide semiconductors (CdS, PbS), grown in precursor-impregnated porous xerogels under different laser irradiations. This review is associated to new results on silver nanocrystals in the same kind of matrices. It is shown that, depending on the employed laser, the particles can be formed near the sample surface or deep inside the silica matrix. Photothermal and/or photochemical mechanisms may be invoked to explain the nanoparticle growth, depending on the laser, precursor, and matrix. One striking result is that metal salt reduction, necessary to the production of the corresponding nanoparticles, can efficiently occur due to the thermal wrenching of electrons from the matrix itself or due to multiphoton absorption of the laser light by a reducer additive in femtosecond regime. Very localized semiconductor quantum dots could also be generated using ultrashort pulses, but while PbS nanoparticles grow faster than CdS particles due to one-photon absorption, this better efficiency is counterbalanced by a sensitivity to oxidation. In most cases where the reaction efficiency is high, particles larger than the pores have been obtained, showing that a fast diffusion of the species through the interconnected porosity can modify the matrix itself. Based on our experience in these techniques, we compare several examples of laser-induced nanocrystal growth in porous silica xerogels, which allows

  3. Advanced Electron Microscopy in Materials Physics

    SciTech Connect

    Zhu, Y.; Jarausch, K.

    2009-06-01

    Aberration correction has opened a new frontier in electron microscopy by overcoming the limitations of conventional round lenses, providing sub-angstrom-sized probes and extending information limits. The imaging and analytical performance of these corrector-equipped microscopes affords an unprecedented opportunity to study structure-property relationships of matter at the atomic scale. This new generation of microscopes is able to retrieve high-quality structural information comparable to neutron and synchrotron x-ray experiments, but with local atomic resolution. These advances in instrumentation are accelerating the research and development of various functional materials ranging from those for energy generation, conversion, transportation and storage to those for catalysis and nano-device applications. The dramatic improvements in electron-beam illumination and detection also present a host of new challenges for the interpretation and optimization of experiments. During 7-9 November 2007, a workshop, entitled 'Aberration Corrected Electron Microscopy in Material Physics', was convened at the Center for Functional Nanomaterials, Brookhaven National Laboratories (BNL) to address these opportunities and challenges. The workshop was co-sponsored by Hitachi High Technologies, a leader in electron microscopy instrumentation, and BNL's Institute of Advanced Electron Microscopy, a leader in materials physics research using electron microscopy. The workshop featured presentations by internationally prominent scientists working at the frontiers of electron microscopy, both on developing instrumentation and applying it in materials physics. The meeting, structured to stimulate scientific exchanges and explore new capabilities, brought together {approx}100 people from over 10 countries. This special issue complies many of the advances in instrument performance and materials physics reported by the invited speakers and attendees at the workshop.

  4. Advanced research workshop: nuclear materials safety

    SciTech Connect

    Jardine, L J; Moshkov, M M

    1999-01-28

    The Advanced Research Workshop (ARW) on Nuclear Materials Safety held June 8-10, 1998, in St. Petersburg, Russia, was attended by 27 Russian experts from 14 different Russian organizations, seven European experts from six different organizations, and 14 U.S. experts from seven different organizations. The ARW was conducted at the State Education Center (SEC), a former Minatom nuclear training center in St. Petersburg. Thirty-three technical presentations were made using simultaneous translations. These presentations are reprinted in this volume as a formal ARW Proceedings in the NATO Science Series. The representative technical papers contained here cover nuclear material safety topics on the storage and disposition of excess plutonium and high enriched uranium (HEU) fissile materials, including vitrification, mixed oxide (MOX) fuel fabrication, plutonium ceramics, reprocessing, geologic disposal, transportation, and Russian regulatory processes. This ARW completed discussions by experts of the nuclear materials safety topics that were not covered in the previous, companion ARW on Nuclear Materials Safety held in Amarillo, Texas, in March 1997. These two workshops, when viewed together as a set, have addressed most nuclear material aspects of the storage and disposition operations required for excess HEU and plutonium. As a result, specific experts in nuclear materials safety have been identified, know each other from their participation in t he two ARW interactions, and have developed a partial consensus and dialogue on the most urgent nuclear materials safety topics to be addressed in a formal bilateral program on t he subject. A strong basis now exists for maintaining and developing a continuing dialogue between Russian, European, and U.S. experts in nuclear materials safety that will improve the safety of future nuclear materials operations in all the countries involved because of t he positive synergistic effects of focusing these diverse backgrounds of

  5. Graded porous inorganic materials derived from self-assembled block copolymer templates

    NASA Astrophysics Data System (ADS)

    Gu, Yibei; Werner, Jörg G.; Dorin, Rachel M.; Robbins, Spencer W.; Wiesner, Ulrich

    2015-03-01

    Graded porous inorganic materials directed by macromolecular self-assembly are expected to offer unique structural platforms relative to conventional porous inorganic materials. Their preparation to date remains a challenge, however, based on the sparsity of viable synthetic self-assembly pathways to control structural asymmetry. Here we demonstrate the fabrication of graded porous carbon, metal, and metal oxide film structures from self-assembled block copolymer templates by using various backfilling techniques in combination with thermal treatments for template removal and chemical transformations. The asymmetric inorganic structures display mesopores in the film top layers and a gradual pore size increase along the film normal in the macroporous sponge-like support structure. Substructure walls between macropores are themselves mesoporous, constituting a structural hierarchy in addition to the pore gradation. Final graded structures can be tailored by tuning casting conditions of self-assembled templates as well as the backfilling processes. We expect that these graded porous inorganic materials may find use in applications including separation, catalysis, biomedical implants, and energy conversion and storage.Graded porous inorganic materials directed by macromolecular self-assembly are expected to offer unique structural platforms relative to conventional porous inorganic materials. Their preparation to date remains a challenge, however, based on the sparsity of viable synthetic self-assembly pathways to control structural asymmetry. Here we demonstrate the fabrication of graded porous carbon, metal, and metal oxide film structures from self-assembled block copolymer templates by using various backfilling techniques in combination with thermal treatments for template removal and chemical transformations. The asymmetric inorganic structures display mesopores in the film top layers and a gradual pore size increase along the film normal in the macroporous sponge

  6. Freeze-drying of “pearl milk tea”: A general strategy for controllable synthesis of porous materials

    PubMed Central

    Zhou, Yingke; Tian, Xiaohui; Wang, Pengcheng; Hu, Min; Du, Guodong

    2016-01-01

    Porous materials have been widely used in many fields, but the large-scale synthesis of materials with controlled pore sizes, pore volumes, and wall thicknesses remains a considerable challenge. Thus, the controllable synthesis of porous materials is of key general importance. Herein, we demonstrate the “pearl milk tea” freeze-drying method to form porous materials with controllable pore characteristics, which is realized by rapidly freezing the uniformly distributed template-containing precursor solution, followed by freeze-drying and suitable calcination. This general and convenient method has been successfully applied to synthesize various porous phosphate and oxide materials using different templates. The method is promising for the development of tunable porous materials for numerous applications of energy, environment, and catalysis, etc. PMID:27193866

  7. Freeze-drying of “pearl milk tea”: A general strategy for controllable synthesis of porous materials

    NASA Astrophysics Data System (ADS)

    Zhou, Yingke; Tian, Xiaohui; Wang, Pengcheng; Hu, Min; Du, Guodong

    2016-05-01

    Porous materials have been widely used in many fields, but the large-scale synthesis of materials with controlled pore sizes, pore volumes, and wall thicknesses remains a considerable challenge. Thus, the controllable synthesis of porous materials is of key general importance. Herein, we demonstrate the “pearl milk tea” freeze-drying method to form porous materials with controllable pore characteristics, which is realized by rapidly freezing the uniformly distributed template-containing precursor solution, followed by freeze-drying and suitable calcination. This general and convenient method has been successfully applied to synthesize various porous phosphate and oxide materials using different templates. The method is promising for the development of tunable porous materials for numerous applications of energy, environment, and catalysis, etc.

  8. GO-induced assembly of gelatin toward stacked layer-like porous carbon for advanced supercapacitors.

    PubMed

    Zhang, Xiaomeng; Jiao, Yanqing; Sun, Li; Wang, Lei; Wu, Aiping; Yan, Haijing; Meng, Meichen; Tian, Chungui; Jiang, Baojiang; Fu, Honggang

    2016-01-28

    Layer-like nanocarbons with high surface area and good conductivity are promising materials for supercapacitors due to their good ability for effective charge-transfer and mass-transfer. In this paper, stacked layer-like porous carbon containing RGO (reduced graphene oxides) (LPCG) was constructed via the GO-induced assembly of gelatin followed by carbonization and activation processes. Under suitable conditions, LPCG-based materials with a thickness of about 100 nm and a high specific surface area (up to 1476 m(2) g(-1)) could be obtained. In the materials, the closed combination of RGO and porous carbon can be observed, which is favourable for the development of the synergistic effects of both components. The presence of GO can not only enhance the conductivity of LPCG-based materials, but also is essential for the formation of a thin carbon sheet with a stacked structure. Otherwise, the plate-like, non-stacked carbon with a thickness of about 500 nm could be formed in the absence of RGO. The porous structure along with the presence of RGO allows rapid charge-transfer and easy access and diffusion of electrolyte ions. As a result, the materials exhibited a high discharge specific capacitance (455 F g(-1) at 0.5 A g(-1), 366 F g(-1) at 1 A g(-1)), good rate capability (221 F g(-1) at density 30 A g(-1)) and good cycling stability. In aqueous electrolytes, the energy density could be up to 9.32 W h kg(-1) at a relatively low power density of 500 W kg(-1) with a good cycling stability (>96% over 5000 cycles). It was found that (1) the rational combination of RGO and porous carbon is essential for enhancing the capacitance performance and improving the cycling stability and (2) the high conductivity is favorable for improving the rate performance of the materials. The LPCG-based materials have extensive potential for practical applications in energy storage and conversion devices.

  9. Variably porous structures

    SciTech Connect

    Braun, Paul V.; Yu, Xindi

    2011-01-18

    A method of making a monolithic porous structure, comprises electrodepositing a material on a template; removing the template from the material to form a monolithic porous structure comprising the material; and electropolishing the monolithic porous structure.

  10. Process of making porous ceramic materials with controlled porosity

    DOEpatents

    Anderson, Marc A.; Ku, Qunyin

    1993-01-01

    A method of making metal oxide ceramic material is disclosed by which the porosity of the resulting material can be selectively controlled by manipulating the sol used to make the material. The method can be used to make a variety of metal oxide ceramic bodies, including membranes, but also pellets, plugs or other bodies. It has also been found that viscous sol materials can readily be shaped by extrusion into shapes typical of catalytic or adsorbent bodies used in industry, to facilitate the application of such materials for catalytic and adsorbent applications.

  11. Recent advances in organic semiconducting materials

    NASA Astrophysics Data System (ADS)

    Ostroverkhova, Oksana

    2011-10-01

    Organic semiconductors have attracted attention due to their low cost, easy fabrication, and tunable properties. Applications of organic materials in thin-film transistors, solar cells, light-emitting diodes, sensors, and many other devices have been actively explored. Recent advances in organic synthesis, material processing, and device fabrication led to significant improvements in (opto)electronic device performance. However, a number of challenges remain. These range from lack of understanding of basic physics of intermolecular interactions that determine optical and electronic properties of organic materials to difficulties in controlling film morphology and stability. In this presentation, current state of the field will be reviewed and recent results related to charge carrier and exciton dynamics in organic thin films will be presented.[4pt] In collaboration with Whitney Shepherd, Mark Kendrick, Andrew Platt, Oregon State University; Marsha Loth and John Anthony, University of Kentucky.

  12. Automotive applications for advanced composite materials

    NASA Technical Reports Server (NTRS)

    Deutsch, G. C.

    1978-01-01

    A description is presented of nonaerospace applications for advanced composite materials with special emphasis on the automotive applications. The automotive industry has to satisfy exacting requirements to reduce the average fuel consumption of cars. A feasible approach to accomplish this involves the development of composites cars with a total weight of 2400 pounds and a fuel consumption of 33 miles per gallon. In connection with this possibility, the automotive companies have started to look seriously at composite materials. The aerospace industry has over the past decade accumulated a considerable data base on composite materials and this is being made available to the nonaerospace sector. However, the automotive companies will place prime emphasis on low cost resins which lend themselves to rapid fabrication techniques.

  13. Advanced reflector materials for solar concentrators

    SciTech Connect

    Jorgensen, G; Williams, T; Wendelin, T

    1994-10-01

    This paper describes the research and development program at the U.S. National Renewable Energy Laboratory (NREL) in advanced reflector materials for solar concentrators. NREL's research thrust is to develop solar reflector materials that maintain high specular reflectance for extended lifetimes under outdoor service conditions and whose cost is significantly lower than existing products. Much of this work has been in collaboration with private-sector companies that have extensive expertise in vacuum-coating and polymer-film technologies. Significant progress and other promising developments will be discussed. These are expected to lead to additional improvements needed to commercialize solar thermal concentration systems and make them economically attractive to the solar manufacturing industry. To explicitly demonstrate the optical durability of candidate reflector materials in real-world service conditions, a network of instrumented outdoor exposure sites has been activated.

  14. International Symposium on Advanced Materials (ISAM 2013)

    NASA Astrophysics Data System (ADS)

    2014-06-01

    This proceeding is a compilation of peer reviewed papers presented at the 13th International Symposium on Advanced Materials (ISAM 2013) held from September 23-27, 2013, at Islamabad, Pakistan. In my capacity as ISAM-2013 Secretary, I feel honoured that the symposium has ended on a positive note. The ever increasing changes and intricacies that characterize modern industry necessitate a growing demand for technical information on advanced materials. ISAM and other similar forums serve to fulfill this need. The five day deliberations of ISAM 2013, consisted of 19 technical sessions and 2 poster sessions. In all, 277 papers were presented, inclusive of 80 contributory, invited and oral presentations. The symposium also hosted panel discussions led by renowned scientists and eminent researchers from foreign as well as local institutes. The ultimate aim of this proceeding is to record in writing the new findings in the field of advanced materials. I hope that the technical data available in this publication proves valuable to young scientists and researchers working in this area of science. At the same time, I wish to acknowledge Institute of Physics (IOP) Publishing UK, for accepting the research papers from ISAM-2013 for publication in the IOP Conference Series: Materials Science and Engineering. The proceeding will be available on the IOP website as an online open access document. I am profoundly thankful to the Symposium Chairman for his steadfast support and valuable guidance without which ISAM 2013 could not have been the mega event that it turned out to be. My gratitude to all our distinguished participants, session chairs/co-chairs, and reviewers for their active role in the symposium. I appreciate the entire organizing committee for the zest and ardor with which each committee fulfilled its obligations to ISAM. Last yet not the least, my thankfulness goes to all our sponsors for wilfully financing the event. Dr. Sara Qaisar Symposium Secretary Further

  15. Measurements of Acoustic Properties of Porous and Granular Materials and Application to Vibration Control

    NASA Technical Reports Server (NTRS)

    Park, Junhong; Palumbo, Daniel L.

    2004-01-01

    For application of porous and granular materials to vibro-acoustic controls, a finite dynamic strength of the solid component (frame) is an important design factor. The primary goal of this study was to investigate structural vibration damping through this frame wave propagation for various poroelastic materials. A measurement method to investigate the vibration characteristics of the frame was proposed. The measured properties were found to follow closely the characteristics of the viscoelastic materials - the dynamic modulus increased with frequency and the degree of the frequency dependence was determined by its loss factor. The dynamic stiffness of hollow cylindrical beams containing porous and granular materials as damping treatment was measured also. The data were used to extract the damping materials characteristics using the Rayleigh-Ritz method. The results suggested that the acoustic structure interaction between the frame and the structure enhances the dissipation of the vibration energy significantly.

  16. Dimpled elastic sheets: a new class of non-porous negative Poisson’s ratio materials

    PubMed Central

    Javid, Farhad; Smith-Roberge, Evelyne; Innes, Matthew C.; Shanian, Ali; Weaver, James C.; Bertoldi, Katia

    2015-01-01

    In this study, we report a novel periodic material with negative Poisson’s ratio (also called auxetic materials) fabricated by denting spherical dimples in an elastic flat sheet. While previously reported auxetic materials are either porous or comprise at least two phases, the material proposed here is non-porous and made of a homogeneous elastic sheet. Importantly, the auxetic behavior is induced by a novel mechanism which exploits the out-of-plane deformation of the spherical dimples. Through a combination of experiments and numerical analyses, we demonstrate the robustness of the proposed concept, paving the way for developing a new class of auxetic materials that significantly expand their design space and possible applications. PMID:26671169

  17. Dimpled elastic sheets: a new class of non-porous negative Poisson’s ratio materials

    NASA Astrophysics Data System (ADS)

    Javid, Farhad; Smith-Roberge, Evelyne; Innes, Matthew C.; Shanian, Ali; Weaver, James C.; Bertoldi, Katia

    2015-12-01

    In this study, we report a novel periodic material with negative Poisson’s ratio (also called auxetic materials) fabricated by denting spherical dimples in an elastic flat sheet. While previously reported auxetic materials are either porous or comprise at least two phases, the material proposed here is non-porous and made of a homogeneous elastic sheet. Importantly, the auxetic behavior is induced by a novel mechanism which exploits the out-of-plane deformation of the spherical dimples. Through a combination of experiments and numerical analyses, we demonstrate the robustness of the proposed concept, paving the way for developing a new class of auxetic materials that significantly expand their design space and possible applications.

  18. Advanced Functional Materials for Energy Related Applications

    NASA Astrophysics Data System (ADS)

    Sasan, Koroush

    The current global heavy dependency on fossil fuels gives rise to two critical problems: I) fossil fuels will be depleted in the near future; II) the release of green house gas CO2 generated by the combustion of fossil fuels contributes to global warming. To potentially address both problems, this dissertation documents three primary areas of investigation related to the development of alternative energy sources: electrocatalysts for fuel cells, photocatalysts for hydrogen generation, and photoreduction catalysts for converting CO2 to CH4. Fuel cells could be a promising source of alternative energy. Decreasing the cost and improving the durability and power density of Pt/C as a catalyst for reducing oxygen are major challenges for developing fuel cells. To address these concerns, we have synthesized a Nitrogen-Sulfur-Iron-doped porous carbon material. Our results indicate that the synthesized catalyst exhibits not only higher current density and stability but also higher tolerance to crossover chemicals than the commercial Pt/C catalyst. More importantly, the synthetic method is simple and inexpensive. Using photocatalysts and solar energy is another potential alternative solution for energy demand. We have synthesized a new biomimetic heterogeneous photocatalyst through the incorporation of homogeneous complex 1 [(i-SCH 2)2NC(O)C5H4N]-Fe2(CO) 6] into the highly robust zirconium-porphyrin based metal-organic framework (ZrPF). As photosensitizer ZrPF absorbs the visible light and produces photoexcited electrons that can be transferred through axial covalent bond to di-nuclear complex 1 for hydrogen generation. Additionally, we have studied the photoreduction of CO2 to CH4 using self-doped TiO2 (Ti+3@TiO 2) as photocatalytic materials. The incorporation of Ti3+ into TiO2 structures narrows the band gap, leading to significantly increased photocatalytic activity for the reduction of CO2 into renewable hydrocarbon fuel in the presence of water vapor under visible

  19. Nondestructive evaluation of advanced ceramic composite materials

    SciTech Connect

    Lott, L.A.; Kunerth, D.C.; Walter, J.B.

    1991-09-01

    Nondestructive evaluation techniques were developed to characterize performance degrading conditions in continuous fiber-reinforced silicon carbide/silicon carbide composites. Porosity, fiber-matrix interface bond strength, and physical damage were among the conditions studied. The material studied is formed by chemical vapor infiltration (CVI) of the matrix material into a preform of woven reinforcing fibers. Acoustic, ultrasonic, and vibration response techniques were studied. Porosity was investigated because of its inherent presence in the CVI process and of the resultant degradation of material strength. Correlations between porosity and ultrasonic attenuation and velocity were clearly demonstrated. The ability of ultrasonic transmission scanning techniques to map variations in porosity in a single sample was also demonstrated. The fiber-matrix interface bond was studied because of its importance in determining the fracture toughness of the material. Correlations between interface bonding and acoustic and ultrasonic properties were observed. These results are presented along with those obtained form acoustic and vibration response measurements on material samples subjected to mechanical impact damage. This is the final report on research sponsored by the US Department of Energy, Fossil Energy Advanced Research and Technology Development Materials Program. 10 refs., 24 figs., 2 tabs.

  20. Highly Porous Materials with Unique Mechanical Properties from Smart Capillary Suspensions.

    PubMed

    Dittmann, Jens; Maurath, Johannes; Bitsch, Boris; Willenbacher, Norbert

    2016-02-24

    Smart capillary suspensions are used to fabricate macroporous solids with unique features regarding porosity and mechanical strength from a wide range of materials, including carbon layers and polyethylene membranes, even if sintering or high-temperature treatment is not feasible. High-strength porous ceramics are obtained, tailoring neck and pore shape via controlled deposition of fine particles at the sintering necks. PMID:26677099

  1. Elastic constants of Transversely Isotropically Porous (TIP) materials

    SciTech Connect

    Tuchinskii, L.I.; Kalimova, N.L.

    1994-11-01

    The authors derive formulas describing the dependence of the elastic characteristics of multicapillary materials on the capillary porosity. The investigated materials are classified as transversely isotropic, and the anisotropy in their properties is the result of the directionality of the capillary pores. Analysis of the dependences obtained has shown that the elasticity moduli of these materials may be calculated using formulas suggested for reinforced materials, in which the elastic constants of the fibers are assumed to be equal to zero. The authors derive a relation between the Poisson`s ratios and the capillary porosity.

  2. The recycling dilemma for advanced materials use: Automobile materials substitution

    SciTech Connect

    Field, F.R. III; Clark, J.P. )

    1991-01-01

    This paper discusses the difficulties associated with imposing recycling imperatives upon advanced materials development by examining the case of automotive materials substitution and its impacts upon the recyclability of the automobile. Parallels are drawn between today's issues, which focus upon the recyclability of the increasing polymeric fraction in automobile shredder fluff, and the junked automobile problem of the 1960's, when the problem of abandoned automobiles became a part of the environmental and legislative agenda in the US and overseas. In the 1960's, both the source and the resolution of the junk automobile problem arose through a confluence of technological and economic factors, rather than through any set of regulatory influences. The rise of electric arc furnace steelmaking and the development of the automobile shredder were sufficient to virtually eliminate the problem - so much so that today's problems are incorrectly viewed as novelties. Today's automobile recycling problem again derives from technological and economic factors, but regulatory influences have spurred some of them. While there are no lack of technological solutions to the problem of automobile shredder fluff, none of these solutions yet provides scrap processors with the kind of profit opportunity necessary to implement them. In some ways, it is implicit in advanced materials markets that there is little to no demand for recycled forms of these materials, and, in the absence of these markets, there are few reasons to expect that the solution to today's problems will be quite so neat.

  3. ASME Material Challenges for Advanced Reactor Concepts

    SciTech Connect

    Piyush Sabharwall; Ali Siahpush

    2013-07-01

    This study presents the material Challenges associated with Advanced Reactor Concept (ARC) such as the Advanced High Temperature Reactor (AHTR). ACR are the next generation concepts focusing on power production and providing thermal energy for industrial applications. The efficient transfer of energy for industrial applications depends on the ability to incorporate cost-effective heat exchangers between the nuclear heat transport system and industrial process heat transport system. The heat exchanger required for AHTR is subjected to a unique set of conditions that bring with them several design challenges not encountered in standard heat exchangers. The corrosive molten salts, especially at higher temperatures, require materials throughout the system to avoid corrosion, and adverse high-temperature effects such as creep. Given the very high steam generator pressure of the supercritical steam cycle, it is anticipated that water tube and molten salt shell steam generators heat exchanger will be used. In this paper, the ASME Section III and the American Society of Mechanical Engineers (ASME) Section VIII requirements (acceptance criteria) are discussed. Also, the ASME material acceptance criteria (ASME Section II, Part D) for high temperature environment are presented. Finally, lack of ASME acceptance criteria for thermal design and analysis are discussed.

  4. Porous organic material from discotic tricarboxyamide: side chain-core interactions.

    PubMed

    Jana, Poulami; Paikar, Arpita; Bera, Santu; Maity, Suman Kumar; Haldar, Debasish

    2014-01-01

    The benzene-1,3,5-tricarboxyamide containing three l-methionine (1) self-assemble through 3-fold amide-amide hydrogen bonds and π-π stacking to fabricate one-dimensional nanorod like structure. However, the tyrosine analogue (2) carrying multiple H-bonding side chains lost the C3 symmetry and 3-fold amide-amide hydrogen bonds and developed a porous structure. The porous material exhibits ten times more N2 sorption (155 cc/g) than the columnar one, indicating that side chain-core interactions have a drastic effect on structure and function.

  5. Controlled High-Rate-Strain Shear Bands in Inert and Reactant Porous Materials

    NASA Astrophysics Data System (ADS)

    Nesterenko, Vitali

    1997-07-01

    Shear localization was considered as one of the main reasons for initiation of chemical reaction in energetic materials under dynamic loading (Dremin and Breusov 1968, Winter and Field 1975, Frey 1981, Kipp 1985, Iyer, Bennet et al., 1994) and for particles bonding during shock compaction (Nesterenko 1985). However despite of wide spread recognition of the importance of rapid shear flow the shear bands in porous heterogeneous materials did not become an object of research. The primary reason for this was a lack of appropriate experimental method. The "Thick-Walled Cylinder" method, which allows to reproduce shear bands in controlled conditions, was initially proposed by Nesterenko et al., 1989 for solid inert materials and then modified by Nesterenko, Meyers et al., 1994 to fit porous inert and energetic materials. The method allows to reproduce the array of shear bands with shear strains 10 - 100 and strain rate 107 s-1. Experimental results will be presented for inert materials (granular, fractured ceramics) and for reactant porous mixtures (Nb-Si, Ti-Si, Ti-C). Mechanisms of material deformation and shear induced chemical reactions inside shear localization zone as well as conditions for the initiation of the chemical reaction in the bulk of energetic material by array of shear bands will be considered.

  6. Advanced Technology Composite Fuselage - Materials and Processes

    NASA Technical Reports Server (NTRS)

    Scholz, D. B.; Dost, E. F.; Flynn, B. W.; Ilcewicz, L. B.; Nelson, K. M.; Sawicki, A. J.; Walker, T. H.; Lakes, R. S.

    1997-01-01

    The goal of Boeing's Advanced Technology Composite Aircraft Structures (ATCAS) program was to develop the technology required for cost and weight efficient use of composite materials in transport fuselage structure. This contractor report describes results of material and process selection, development, and characterization activities. Carbon fiber reinforced epoxy was chosen for fuselage skins and stiffening elements and for passenger and cargo floor structures. The automated fiber placement (AFP) process was selected for fabrication of monolithic and sandwich skin panels. Circumferential frames and window frames were braided and resin transfer molded (RTM'd). Pultrusion was selected for fabrication of floor beams and constant section stiffening elements. Drape forming was chosen for stringers and other stiffening elements. Significant development efforts were expended on the AFP, braiding, and RTM processes. Sandwich core materials and core edge close-out design concepts were evaluated. Autoclave cure processes were developed for stiffened skin and sandwich structures. The stiffness, strength, notch sensitivity, and bearing/bypass properties of fiber-placed skin materials and braided/RTM'd circumferential frame materials were characterized. The strength and durability of cocured and cobonded joints were evaluated. Impact damage resistance of stiffened skin and sandwich structures typical of fuselage panels was investigated. Fluid penetration and migration mechanisms for sandwich panels were studied.

  7. GO-induced assembly of gelatin toward stacked layer-like porous carbon for advanced supercapacitors

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaomeng; Jiao, Yanqing; Sun, Li; Wang, Lei; Wu, Aiping; Yan, Haijing; Meng, Meichen; Tian, Chungui; Jiang, Baojiang; Fu, Honggang

    2016-01-01

    Layer-like nanocarbons with high surface area and good conductivity are promising materials for supercapacitors due to their good ability for effective charge-transfer and mass-transfer. In this paper, stacked layer-like porous carbon containing RGO (reduced graphene oxides) (LPCG) was constructed via the GO-induced assembly of gelatin followed by carbonization and activation processes. Under suitable conditions, LPCG-based materials with a thickness of about 100 nm and a high specific surface area (up to 1476 m2 g-1) could be obtained. In the materials, the closed combination of RGO and porous carbon can be observed, which is favourable for the development of the synergistic effects of both components. The presence of GO can not only enhance the conductivity of LPCG-based materials, but also is essential for the formation of a thin carbon sheet with a stacked structure. Otherwise, the plate-like, non-stacked carbon with a thickness of about 500 nm could be formed in the absence of RGO. The porous structure along with the presence of RGO allows rapid charge-transfer and easy access and diffusion of electrolyte ions. As a result, the materials exhibited a high discharge specific capacitance (455 F g-1 at 0.5 A g-1, 366 F g-1 at 1 A g-1), good rate capability (221 F g-1 at density 30 A g-1) and good cycling stability. In aqueous electrolytes, the energy density could be up to 9.32 W h kg-1 at a relatively low power density of 500 W kg-1 with a good cycling stability (>96% over 5000 cycles). It was found that (1) the rational combination of RGO and porous carbon is essential for enhancing the capacitance performance and improving the cycling stability and (2) the high conductivity is favorable for improving the rate performance of the materials. The LPCG-based materials have extensive potential for practical applications in energy storage and conversion devices.Layer-like nanocarbons with high surface area and good conductivity are promising materials for

  8. High-speed neutron radiography for monitoring the water absorption by capillarity in porous materials

    NASA Astrophysics Data System (ADS)

    Cnudde, Veerle; Dierick, Manuel; Vlassenbroeck, Jelle; Masschaele, Bert; Lehmann, Eberhard; Jacobs, Patric; Van Hoorebeke, Luc

    2008-01-01

    Fluid flow through porous natural building stones is of great importance when studying their weathering processes. Many traditional experiments based on mass changes are available for studying liquid transport in porous stones, such as the determination of the water absorption coefficient by capillarity. Because thermal neutrons experience a strong attenuation by hydrogen, neutron radiography is a suitable technique for the study of water absorption by capillarity in porous stones. However, image contrast can be impaired because hydrogen mainly scatters neutrons rather than absorbing them, resulting in a blurred image. Capillarity results obtained by neutron radiography and by the European Standard 1925 for the determination of the water absorption coefficient by capillarity for natural building stones with a variable porosity were compared. It is illustrated that high-speed neutron radiography can be a useful research tool for the visualization of internal fluid flow inside inorganic building materials such as limestones and sandstones.

  9. Characterization of Porous Materials by Fluorescence Correlation Spectroscopy Super-resolution Optical Fluctuation Imaging.

    PubMed

    Kisley, Lydia; Brunetti, Rachel; Tauzin, Lawrence J; Shuang, Bo; Yi, Xiyu; Kirkeminde, Alec W; Higgins, Daniel A; Weiss, Shimon; Landes, Christy F

    2015-09-22

    Porous materials such as cellular cytosol, hydrogels, and block copolymers have nanoscale features that determine macroscale properties. Characterizing the structure of nanopores is difficult with current techniques due to imaging, sample preparation, and computational challenges. We produce a super-resolution optical image that simultaneously characterizes the nanometer dimensions of and diffusion dynamics within porous structures by correlating stochastic fluctuations from diffusing fluorescent probes in the pores of the sample, dubbed here as "fluorescence correlation spectroscopy super-resolution optical fluctuation imaging" or "fcsSOFI". Simulations demonstrate that structural features and diffusion properties can be accurately obtained at sub-diffraction-limited resolution. We apply our technique to image agarose hydrogels and aqueous lyotropic liquid crystal gels. The heterogeneous pore resolution is improved by up to a factor of 2, and diffusion coefficients are accurately obtained through our method compared to diffraction-limited fluorescence imaging and single-particle tracking. Moreover, fcsSOFI allows for rapid and high-throughput characterization of porous materials. fcsSOFI could be applied to soft porous environments such hydrogels, polymers, and membranes in addition to hard materials such as zeolites and mesoporous silica.

  10. Advanced Materials Laboratory User Test Planning Guide

    NASA Technical Reports Server (NTRS)

    Orndoff, Evelyne

    2012-01-01

    Test process, milestones and inputs are unknowns to first-time users of the Advanced Materials Laboratory. The User Test Planning Guide aids in establishing expectations for both NASA and non-NASA facility customers. The potential audience for this guide includes both internal and commercial spaceflight hardware/software developers. It is intended to assist their test engineering personnel in test planning and execution. Material covered includes a roadmap of the test process, roles and responsibilities of facility and user, major milestones, facility capabilities, and inputs required by the facility. Samples of deliverables, test article interfaces, and inputs necessary to define test scope, cost, and schedule are included as an appendix to the guide.

  11. On the fracture toughness of advanced materials

    SciTech Connect

    Launey, Maximilien E.; Ritchie, Robert O.

    2008-11-24

    Few engineering materials are limited by their strength; rather they are limited by their resistance to fracture or fracture toughness. It is not by accident that most critical structures, such as bridges, ships, nuclear pressure vessels and so forth, are manufactured from materials that are comparatively low in strength but high in toughness. Indeed, in many classes of materials, strength and toughness are almost mutually exclusive. In the first instance, such resistance to fracture is a function of bonding and crystal structure (or lack thereof), but can be developed through the design of appropriate nano/microstructures. However, the creation of tough microstructures in structural materials, i.e., metals, polymers, ceramics and their composites, is invariably a compromise between resistance to intrinsic damage mechanisms ahead of the tip of a crack (intrinsic toughening) and the formation of crack-tip shielding mechanisms which principally act behind the tip to reduce the effective 'crack-driving force' (extrinsic toughening). Intrinsic toughening is essentially an inherent property of a specific microstructure; it is the dominant form of toughening in ductile (e.g., metallic) materials. However, for most brittle (e.g., ceramic) solids, and this includes many biological materials, it is largely ineffective and toughening conversely must be developed extrinsically, by such shielding mechanisms as crack bridging. From a fracture mechanics perspective, this results in toughening in the form of rising resistance-curve behavior where the fracture resistance actually increases with crack extension. The implication of this is that in many biological and high-strength advanced materials, toughness is developed primarily during crack growth and not for crack initiation. This is an important realization yet is still rarely reflected in the way that toughness is measured, which is invariably involves the use of single-value (crack-initiation) parameters such as the

  12. Mechanically Strong, Lightweight Porous Materials Developed (X-Aerogels)

    NASA Technical Reports Server (NTRS)

    Leventis, Nicholas

    2005-01-01

    Aerogels are attractive materials for a variety of NASA missions because they are ultralightweight, have low thermal conductivity and low-dielectric constants, and can be readily doped with other materials. Potential NASA applications for these materials include lightweight insulation for spacecraft, habitats, and extravehicular activity (EVA) suits; catalyst supports for fuel cell and in situ resource utilization; and sensors for air- and water-quality monitoring for vehicles, habitats, and EVA suits. Conventional aerogels are extremely fragile and require processing via supercritical fluid extraction, which adds cost to the production of an aerogel and limits the sizes and geometries of samples that can be produced from these materials. These issues have severely hampered the application of aerogels in NASA missions.

  13. NREL Advances Spillover Materials for Hydrogen Storage (Fact Sheet)

    SciTech Connect

    Not Available

    2010-12-01

    This fact sheet describes NREL's accomplishments in advancing spillover materials for hydrogen storage and improving the reproducible synthesis, long-term durability, and material costs of hydrogen storage materials. Work was performed by NREL's Chemical and Materials Science Center.

  14. The Interaction of Sound and Shock Waves with Flexible Porous Materials

    NASA Astrophysics Data System (ADS)

    Abbott, James Fuller

    Several topics are studied which illustrate the role of flexibility in determining the acoustical properties of flexible porous materials. A power balance relation is obtained for the flexible porous material which explicitly identifies two loss mechanisms for sound absorption: the losses due to the irreversible deformation of the structure, and those attributed to the viscous drag between the fluid and the structure. The finite flexible porous layer backed by a rigid wall is then considered. Irreversible deformation of the structure is shown to be the dominant loss mechanism for closed layers. Three departures from the basic model-- a porous layer with anisotropic flow resistance and structure factor, periodic structures consisting of porous layers separated by air gaps, and the porous medium in bulk with mean fluid flow--are considered. The reflection of shock waves is also studied, and a quasi-linear theory is developed which reproduces the principal features of experimental results obtained previously by Ingard. The theory assumes that the propagating pulses in the air and structure are linear and the gross, zeroth order motion of the porous layer is modeled by including its energy and momentum in the conservation equations; these equations compare the system just before and just after the reflection of the incident shock from the front surface of the layer. The substantial motion of the layer and its dragging against a constraining boundary (in this case the walls of the shock tube) are found to introduce a dependence of the front reflection coefficient and maximal layer deformation on the peak pressure of the incident shock. Lastly, we address the question of measurement of the complex compressibility K, a key parameter used to describe the dynamics of a given flexible porous material. The standard long-wavelength assumption used to determine K from experimental measurements of the frequency dependent velocity transfer function across a sample is shown to

  15. Ultrathin coatings of nanoporous materials as property enhancements for advanced functional materials.

    SciTech Connect

    Coker, Eric Nicholas

    2010-11-01

    This report summarizes the findings of a five-month LDRD project funded through Sandia's NTM Investment Area. The project was aimed at providing the foundation for the development of advanced functional materials through the application of ultrathin coatings of microporous or mesoporous materials onto the surface of substrates such as silicon wafers. Prior art teaches that layers of microporous materials such as zeolites may be applied as, e.g., sensor platforms or gas separation membranes. These layers, however, are typically several microns to several hundred microns thick. For many potential applications, vast improvements in the response of a device could be realized if the thickness of the porous layer were reduced to tens of nanometers. However, a basic understanding of how to synthesize or fabricate such ultra-thin layers is lacking. This report describes traditional and novel approaches to the growth of layers of microporous materials on silicon wafers. The novel approaches include reduction of the quantity of nutrients available to grow the zeolite layer through minimization of solution volume, and reaction of organic base (template) with thermally-oxidized silicon wafers under a steam atmosphere to generate ultra-thin layers of zeolite MFI.

  16. Potential of hybrid functionalized meso-porous materials for the separation and immobilization of radionuclides

    SciTech Connect

    Luca, V.

    2013-07-01

    Functionalized meso-porous materials are a class of hybrid organic-inorganic material in which a meso-porous metal oxide framework is functionalized with multifunctional organic molecules. These molecules may contain one or more anchor groups that form strong bonds to the pore surfaces of the metal oxide framework and free functional groups that can impart and or modify the functionality of the material such as for binding metal ions in solution. Such materials have been extensively studied over the past decade and are of particular interest in absorption applications because of the tremendous versatility in choosing the composition and architecture of the metal oxide framework and the nature of the functional organic molecule as well as the efficient mass transfer that can occur through a well-designed hierarchically porous network. A sorbent for nuclear applications would have to be highly selective for particular radio nuclides, it would need to be hydrolytically and radiolytically stable, and it would have to possess reasonable capacity and fast kinetics. The sorbent would also have to be available in a form suitable for use in a column. Finally, it would also be desirable if once saturated with radio nuclides, the sorbent could be recycled or converted directly into a ceramic or glass waste form suitable for direct repository disposal or even converted directly into a material that could be used as a transmutation target. Such a cradle-to- grave strategy could have many benefits in so far as process efficiency and the generation of secondary wastes are concerned.This paper will provide an overview of work done on all of the above mentioned aspects of the development of functionalized meso-porous adsorbent materials for the selective separation of lanthanides and actinides and discuss the prospects for future implementation of a cradle-to-grave strategy with such materials. (author)

  17. Supersonic flow around a cylinder with front gas-permeable insert which modeled by skeleton of porous material

    NASA Astrophysics Data System (ADS)

    Poplavskaya, T. V.; Kirilovskiy, S. V.; Mironov, S. G.

    2016-10-01

    Experimental data and results of numerical simulation of a supersonic flow around a streamwise aligned cylinder with a frontal gas-permeable insert made of a high-porosity cellular material are presented. The porous material structure is modeled by a system of staggered rings of different diameters (discrete model of a porous medium). The model skeleton of the material corresponds to the pore size (diameter 1mm) and porosity (0.95) of a real cellular porous material. The computed results are compared with the data of wind tunnel experiments performed in a T-327B supersonic continuous-flow wind tunnel at the flow Mach number M∞ = 4.85.

  18. Getting Out Of A Tight Spot: Physics Of Flow Through Porous Materials

    NASA Astrophysics Data System (ADS)

    Datta, Sujit Sankar

    We study the physics of flow through porous materials in two different ways: by directly visualizing flow through a model three-dimensional (3D) porous medium, and by investigating the deformability of fluid-filled microcapsules having porous shells. In the first part of this thesis, we develop an experimental approach to directly visualize fluid flow through a 3D porous medium. We use this to investigate drainage, the displacement of a wetting fluid from a porous medium by a non-wetting fluid, as well as secondary imbibition, the subsequent displacement of the non-wetting fluid by the wetting fluid. We characterize the intricate morphologies of the non-wetting fluid ganglia left trapped within the pore space, and show how the ganglia configurations vary with the wetting fluid flow rate. We then visualize the spatial fluctuations in the fluid flow, both for single- and multi-phase flow. We use our measurements to quantify the strong variability in the flow velocities, as well as the pore-scale correlations in the flow. Finally, we use our experimental approach to study the simultaneous flow of both a wetting and a non-wetting fluid through a porous medium, and elucidate the flow instabilities that arise for sufficiently large flow rates. In the second part of this thesis, we study the mechanical properties of porous spherical microcapsules. We first introduce emulsions, and describe how their rheology depends on the microscopic interactions between the drops comprising them. We then study the formation and buckling of one class of microcapsule -- nanoparticle-coated emulsion drops. We also use double emulsions, drops within drops, as templates to form another class of microcapsule -- drops coated with thin, porous, polymer shells. We investigate how, under sufficient osmotic pressure, these microcapsules buckle, and show how the inhomogeneity in the shell structure can guide the folding pathway taken by a microcapsule as it buckles. Finally, we study the expansion

  19. Computing the Seismic Attenuation in Complex Porous Materials

    NASA Astrophysics Data System (ADS)

    Masson, Yder Jean

    The present work analyzes seismic attenuation due to wave-induced flow in complex poroelastic materials containing an arbitrary amount of heterogeneity and fully or partially saturated with a mixture of fluids. In the first part, two distinct finite-difference (FDTD) numerical schemes for solving Biot's poroelastic set of equations are introduced. The first algorithm is designed to be used in the seismic band of frequencies; i.e., when the permeability of the medium doesn't depend on frequency. The second algorithm accounts for viscous boundary layers that appear in the pores at high frequencies (in this case, the permeability depends on frequency) and can be used across the entire band of frequencies. An innovative numerical method is presented in the second part allowing computation of seismic attenuation due to wave-induced flow for any poroelastic material. This method is applied to study the attenuation associated with different classes of materials saturated with a single fluid (water). For a material having a self-affine (fractal) distribution of elastic properties, it is demonstrated that frequency dependence in the attenuation is controlled by a single parameter that is directly related to the fractal dimension of the material. For anisotropic materials, a relation is established between the attenuation levels associated with waves propagating in different directions and the geometrical aspect ratio of the heterogeneities present within the material. The third part concerns the study of attenuation associated with materials having a homogeneous solid skeleton saturated with a mixture of immiscible fluids. The special case where the distribution of fluids is the result of an invasion-percolation process is treated in detail. Finally, the last part presents a novel experimental setup designed to measure fluctuations of the elastic properties in real rock samples. This device performs automated micro-indentation tests at the surface of rock samples and

  20. Electrode including porous particles with embedded active material for use in a secondary electrochemical cell

    DOEpatents

    Vissers, Donald R.; Nelson, Paul A.; Kaun, Thomas D.; Tomczuk, Zygmunt

    1978-04-25

    Particles of carbonaceous matrices containing embedded electrode active material are prepared for vibratory loading within a porous electrically conductive substrate. In preparing the particles, active materials such as metal chalcogenides, solid alloys of alkali or alkaline earth metals along with other metals and their oxides in powdered or particulate form are blended with a thermosetting resin and particles of a volatile to form a paste mixture. The paste is heated to a temperature at which the volatile transforms into vapor to impart porosity at about the same time as the resin begins to cure into a rigid, solid structure. The solid structure is then comminuted into porous, carbonaceous particles with the embedded active material.

  1. Method of preparing porous, active material for use in electrodes of secondary electrochemical cells

    DOEpatents

    Vissers, Donald R.; Nelson, Paul A.; Kaun, Thomas D.; Tomczuk, Zygmunt

    1977-01-01

    Particles of carbonaceous matrices containing embedded electrode active material are prepared for vibratory loading within a porous electrically conductive substrate. In preparing the particles, active materials such as metal chalcogenides, solid alloys of alkali or alkaline earth metals along with other metals and their oxides in powdered or particulate form are blended with a thermosetting resin and particles of a volatile to form a paste mixture. The paste is heated to a temperature at which the volatile transforms into vapor to impart porosity at about the same time as the resin begins to cure into a rigid, solid structure.The solid structure is then comminuted into porous, carbonaceous particles with the embedded active material.

  2. Dark-field X-ray imaging of unsaturated water transport in porous materials

    SciTech Connect

    Yang, F. E-mail: michele.griffa@empa.ch; Di Bella, C.; Lura, P.; Prade, F.; Herzen, J.; Sarapata, A.; Pfeiffer, F.; Griffa, M. E-mail: michele.griffa@empa.ch; Jerjen, I.

    2014-10-13

    We introduce in this Letter an approach to X-ray imaging of unsaturated water transport in porous materials based upon the intrinsic X-ray scattering produced by the material microstructural heterogeneity at a length scale below the imaging system spatial resolution. The basic principle for image contrast creation consists in a reduction of such scattering by permeation of the porosity by water. The implementation of the approach is based upon X-ray dark-field imaging via Talbot-Lau interferometry. The proof-of-concept is provided by performing laboratory-scale dark-field X-ray radiography of mortar samples during a water capillary uptake experiment. The results suggest that the proposed approach to visualizing unsaturated water transport in porous materials is complementary to neutron and magnetic resonance imaging and alternative to standard X-ray imaging, the latter requiring the use of contrast agents because based upon X-ray attenuation only.

  3. Computational study of porous materials for gas separations

    NASA Astrophysics Data System (ADS)

    Lin, Li-Chiang

    Nanoporous materials such as zeolites, zeolitic imidazolate frameworks (ZIFs), and metal-organic frameworks (MOFs) are used as sorbents or membranes for gas separations such as carbon dioxide capture, methane capture, paraffin/olefin separations, etc. The total number of nanoporous materials is large; by changing the chemical composition and/or the structural topologies we can envision an infinite number of possible materials. In practice one can synthesize and fully characterize only a small subset of these materials. Hence, computational study can play an important role by utilizing various techniques in molecular simulations as well as quantum chemical calculations to accelerate the search for optimal materials for various energy-related separations. Accordingly, several large-scale computational screenings of over one hundred thousand materials have been performed to find the best materials for carbon capture, methane capture, and ethane/ethene separation. These large-scale screenings identified a number of promising materials for different applications. Moreover, the analysis of these screening studies yielded insights into those molecular characteristics of a material that contribute to an optimal performance for a given application. These insights provided useful guidelines for future structural design and synthesis. For instance, one of the screening studies indicated that some zeolite structures can potentially reduce the energy penalty imposed on a coal-fired power plant by as much as 35% compared to the near-term MEA technology for carbon capture application. These optimal structures have topologies with a maximized density of pockets and they capture and release CO2 molecules with an optimal energy. These screening studies also pointed to some systems, for which conventional force fields were unable to make sufficiently reliable predictions of the adsorption isotherms of different gasses, e.g., CO2 in MOFs with open-metal sites. For these systems, we

  4. The Limits of Porous Materials in the Topology Optimization of Stokes Flows

    SciTech Connect

    Evgrafov, Anton

    2005-10-15

    We consider a problem concerning the distribution of a solid material in a given bounded control volume with the goal to minimize the potential power of the Stokes flow with given velocities at the boundary through the material-free part of the domain.We also study the relaxed problem of the optimal distribution of the porous material with a spatially varying Darcy permeability tensor, where the governing equations are known as the Darcy-Stokes, or Brinkman, equations. We show that the introduction of the requirement of zero power dissipation due to the flow through the porous material into the relaxed problem results in it becoming a well-posed mathematical problem, which admits optimal solutions that have extreme permeability properties (i.e., assume only zero or infinite permeability); thus, they are also optimal in the original (non-relaxed) problem. Two numerical techniques are presented for the solution of the constrained problem. One is based on a sequence of optimal Brinkman flows with increasing viscosities, from the mathematical point of view nothing but the exterior penalty approach applied to the problem. Another technique is more special, and is based on the 'sizing' approximation of the problem using a mix of two different porous materials with high and low permeabilities, respectively. This paper thus complements the study of Borrvall and Petersson (Internat. J. Numer. Methods Fluids, vol. 41, no. 1, pp. 77-107, 2003), where only sizing optimization problems are treated.

  5. Preparation of steel slag porous sound-absorbing material using coal powder as pore former.

    PubMed

    Sun, Peng; Guo, Zhancheng

    2015-10-01

    The aim of the study was to prepare a porous sound-absorbing material using steel slag and fly ash as the main raw material, with coal powder and sodium silicate used as a pore former and binder respectively. The influence of the experimental conditions such as the ratio of fly ash, sintering temperature, sintering time, and porosity regulation on the performance of the porous sound-absorbing material was investigated. The results showed that the specimens prepared by this method had high sound absorption performance and good mechanical properties, and the noise reduction coefficient and compressive strength could reach 0.50 and 6.5MPa, respectively. The compressive strength increased when the dosage of fly ash and sintering temperature were raised. The noise reduction coefficient decreased with increasing ratio of fly ash and reducing pore former, and first increased and then decreased with the increase of sintering temperature and time. The optimum preparation conditions for the porous sound-absorbing material were a proportion of fly ash of 50% (wt.%), percentage of coal powder of 30% (wt.%), sintering temperature of 1130°C, and sintering time of 6.0hr, which were determined by analyzing the properties of the sound-absorbing material. PMID:26456608

  6. Preparation of steel slag porous sound-absorbing material using coal powder as pore former.

    PubMed

    Sun, Peng; Guo, Zhancheng

    2015-10-01

    The aim of the study was to prepare a porous sound-absorbing material using steel slag and fly ash as the main raw material, with coal powder and sodium silicate used as a pore former and binder respectively. The influence of the experimental conditions such as the ratio of fly ash, sintering temperature, sintering time, and porosity regulation on the performance of the porous sound-absorbing material was investigated. The results showed that the specimens prepared by this method had high sound absorption performance and good mechanical properties, and the noise reduction coefficient and compressive strength could reach 0.50 and 6.5MPa, respectively. The compressive strength increased when the dosage of fly ash and sintering temperature were raised. The noise reduction coefficient decreased with increasing ratio of fly ash and reducing pore former, and first increased and then decreased with the increase of sintering temperature and time. The optimum preparation conditions for the porous sound-absorbing material were a proportion of fly ash of 50% (wt.%), percentage of coal powder of 30% (wt.%), sintering temperature of 1130°C, and sintering time of 6.0hr, which were determined by analyzing the properties of the sound-absorbing material.

  7. Water Adsorption in Porous Metal-Organic Frameworks and Related Materials

    SciTech Connect

    Furukawa, H; Gandara, F; Zhang, YB; Jiang, JC; Queen, WL; Hudson, MR; Yaghi, OM

    2014-03-19

    Water adsorption in porous materials is important for many applications such as dehumidification, thermal batteries, and delivery of drinking water in remote areas. In this study, we have identified three criteria for achieving high performing porous materials for water adsorption. These criteria deal with condensation pressure of water in the pores, uptake capacity, and recyclability and water stability of the material. In search of an excellently performing porous material, we have studied and compared the water adsorption properties of 23 materials, 20 of which are metal organic frameworks (MOFs). Among the MOFs are 10 zirconium(IV) MOFs with a subset of these, MOF-801-SC (single crystal form), -802, -805, -806, -808, -812, and -841 reported for the first time. MOF-801-P (microcrystalline powder form) was reported earlier and studied here for its water adsorption properties. MOF-812 was only made and structurally characterized but not examined for water adsorption because it is a byproduct of MOF-841 synthesis. All the new zirconium MOFs are made from the Zr6O4(OH)(4)(-CO2)(n) secondary building units (n = 6, 8, 10, or 12) and variously shaped carboxyl organic linkers to make extended porous frameworks. The permanent porosity of all 23 materials was confirmed and their water adsorption measured to reveal that MOF-801-P and MOF-841 are the highest performers based on the three criteria stated above; they are water stable, do not lose capacity after five adsorption/desorption cycles, and are easily regenerated at room temperature. An X-ray single-crystal study and a powder neutron diffraction study reveal the position of the water adsorption sites in MOF-801 and highlight the importance of the intermolecular interaction between adsorbed water molecules within the pores.

  8. Numerical determination of the material properties of porous dust cakes

    NASA Astrophysics Data System (ADS)

    Paszun, D.; Dominik, C.

    2008-06-01

    The formation of planetesimals requires the growth of dust particles through collisions. Micron-sized particles must grow by many orders of magnitude in mass. To understand and model the processes during this growth, both the mechanical properties and the interaction cross sections of aggregates with surrounding gas must be well understood. Recent advances in experimental (laboratory) studies now provide the background for pushing numerical aggregate models to a new level. We present the calibration of a previously tested model of aggregate dynamics. We use plastic deformation of surface asperities as the physical model to match the velocities needed for sticking with experimental results. The modified code is then used to compute both the compression strength and the velocity of sound in the aggregate at different densities. We compare these predictions with experimental results and conclude that the new code is capable of studying the properties of small aggregates.

  9. An alternative Biot's displacement formulation for porous materials.

    PubMed

    Dazel, Olivier; Brouard, Bruno; Depollier, Claude; Griffiths, Stéphane

    2007-06-01

    This paper proposes an alternative displacement formulation of Biot's linear model for poroelastic materials. Its advantage is a simplification of the formalism without making any additional assumptions. The main difference between the method proposed in this paper and the original one is the choice of the generalized coordinates. In the present approach, the generalized coordinates are chosen in order to simplify the expression of the strain energy, which is expressed as the sum of two decoupled terms. Hence, new equations of motion are obtained whose elastic forces are decoupled. The simplification of the formalism is extended to Biot and Willis thought experiments, and simpler expressions of the parameters of the three Biot waves are also provided. A rigorous derivation of equivalent and limp models is then proposed. It is finally shown that, for the particular case of sound-absorbing materials, additional simplifications of the formalism can be obtained.

  10. Ductile damage of porous materials with two populations of voids

    NASA Astrophysics Data System (ADS)

    Vincent, Pierre-Guy; Monerie, Yann; Suquet, Pierre

    2008-01-01

    This study is devoted to the modelling of ductile damage in uranium dioxide. This polycrystalline material contains two populations of voids of well separated size. The problem addressed here is the prediction of the effective flow surface of a Gurson material containing randomly oriented oblate voids. The case of spherical voids is considered first and the variational approach of Gurson is generalized by adding a compressible component to his original velocity field. The case of aligned oblate voids is then considered and a suitable generalization of a velocity field due to Gologanu et al. (ASME J. Engrg. Mater. Technol. 116 (1994) 290-297) is proposed. The extension to randomly oriented voids is achieved by averaging over all orientations. In each case, rigorous upper bounds and approximate estimates are derived and compared (in the case of spherical voids) with Finite Element simulations. To cite this article: P.-G. Vincent et al., C. R. Mecanique 336 (2008).

  11. Materials for advanced ultrasupercritical steam turbines

    SciTech Connect

    Purgert, Robert; Shingledecker, John; Saha, Deepak; Thangirala, Mani; Booras, George; Powers, John; Riley, Colin; Hendrix, Howard

    2015-12-01

    The U.S. Department of Energy (DOE) and the Ohio Coal Development Office (OCDO) have sponsored a project aimed at identifying, evaluating, and qualifying the materials needed for the construction of the critical components of coal-fired power plants capable of operating at much higher efficiencies than the current generation of supercritical plants. This increased efficiency is expected to be achieved principally through the use of advanced ultrasupercritical (A-USC) steam conditions. A limiting factor in this can be the materials of construction for boilers and for steam turbines. The overall project goal is to assess/develop materials technology that will enable achieving turbine throttle steam conditions of 760°C (1400°F)/35MPa (5000 psi). This final technical report covers the research completed by the General Electric Company (GE) and Electric Power Research Institute (EPRI), with support from Oak Ridge National Laboratory (ORNL) and the National Energy Technology Laboratory (NETL) – Albany Research Center, to develop the A-USC steam turbine materials technology to meet the overall project goals. Specifically, this report summarizes the industrial scale-up and materials property database development for non-welded rotors (disc forgings), buckets (blades), bolting, castings (needed for casing and valve bodies), casting weld repair, and casting to pipe welding. Additionally, the report provides an engineering and economic assessment of an A-USC power plant without and with partial carbon capture and storage. This research project successfully demonstrated the materials technology at a sufficient scale and with corresponding materials property data to enable the design of an A-USC steam turbine. The key accomplishments included the development of a triple-melt and forged Haynes 282 disc for bolted rotor construction, long-term property development for Nimonic 105 for blading and bolting, successful scale-up of Haynes 282 and Nimonic 263 castings using

  12. Characterization of Porous Carbon Fibers and Related Materials

    SciTech Connect

    Fuller, E.L., Jr.

    1993-01-01

    A one-year subcontract sponsored by the Carbon Materials Technology Group of the Oak Ridge National Laboratory (ORNL) with the Department of Geological Sciences, University Of Tennessee, has been completed. A volumetric sorption system has been upgraded, in cooperation with commercial vendor, to allow the acquisition of data relevant to the program for the production of activated carbon molecular fiber sieves (ACFMS). The equipment and experimental techniques have been developed to determine the pore structure and porosity of reference materials and materials produced at ORNL as part of the development of methods for the activation of carbon fibers by various etching agents. Commercial activated coconut shell charcoal (ACSC) has been studied to verify instrument performance and to develop methodology for deducing cause and effects in the activation processes and to better understand the industrial processes (gas separation, natural gas storage, etc.). Operating personnel have been trained, standard operating procedures have been established, and quality assurance procedures have been developed and put in place. Carbon dioxide and methane sorption have been measured over a temperature range 0 to 200 C for both ACFMS and ACSC and similarities and differences related to the respective structures and mechanisms of interaction with the sorbed components. Nitrogen sorption (at 77 K) has been used to evaluate ''surface area'' and ''porosity'' for comparison with the large data base that exists for other activated carbons and related materials. The preliminary data base reveals that techniques and theories currently used to evaluate activated carbons may be somewhat erroneous and misleading. Alternate thermochemical and structural analyses have been developed that show promise in providing useful information related both to the activation process and to industrial applications of interest in the efficient and economical utilization of fossil fuels in a manner that is

  13. Quantitative properties of complex porous materials calculated from x-ray μCT images

    NASA Astrophysics Data System (ADS)

    Sheppard, Adrian P.; Arns, Christoph H.; Sakellariou, Arthur; Senden, Tim J.; Sok, Rob M.; Averdunk, Holger; Saadatfar, Mohammad; Limaye, Ajay; Knackstedt, Mark A.

    2006-08-01

    numerical laboratory approach to the study of complex porous materials.

  14. Preliminary results on the abradability of porous, sintered seal material

    NASA Technical Reports Server (NTRS)

    Wolak, J.; Emery, A. F.; Etemad, S.; Choi, S. R.

    1982-01-01

    Preliminary results are presented for the case of titanium blade specimens, with bare tips (or covered with wear resistant, plasma sprayed materials) rubbing at 100 m/s against specimens of abradable nickel-chromium seal material moving toward the rotating blades at 0.0125 mm/s or at 0.025 mm/s. Using a two component dynamometer, the normal force of the rub interaction was measured and the shear component estimated. The elastoplastic properties of the seal material have been determined and those parameters as well as the rigidity of the rub tester system are considered in conjunction with those affecting the accuracy of the measurement of the forces arising at the blade-seal interface. The average and the 'local instantaneous' temperatures of the seal specimen and the temperature of the blade tip surface during rubbing are presented as functions of time. A seal densification factor is defined and its functional relationships with contact force components, temperature, wear ratio and blade tip abrading capability are indicated.

  15. Polymers as advanced materials for desiccant applications

    SciTech Connect

    Czanderna, A.W.

    1990-12-01

    This research is concerned with solid materials used as desiccants for desiccant cooling systems (DCSs) that process water vapor in an atmosphere to produce cooling. Background information includes an introduction to DCSs and the role of the desiccant as a system component. The water vapor sorption performance criteria used for screening the modified polymers prepared include the water sorption capacity from 5% to 80% relative humidity (R.H.), isotherm shape, and rate of adsorption and desorption. Measurements are presented for the sorption performance of modified polymeric advanced desiccant materials with the quartz crystal microbalance. Isotherms of polystyrene sulfonic acid (PSSA) taken over a 5-month period show that the material has a dramatic loss in capacity and that the isotherm shape is time dependent. The adsorption and desorption kinetics for PSSA and all the ionic salts of it studied are easily fast enough for commercial DCS applications with a wheel rotation speed of 6 min per revolution. Future activities for the project are addressed, and a 5-year summary of the project is included as Appendix A. 34 refs., 20 figs., 3 tabs.

  16. Thermal fatigue durability for advanced propulsion materials

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.

    1989-01-01

    A review is presented of thermal and thermomechanical fatigue (TMF) crack initiation life prediction and cyclic constitutive modeling efforts sponsored recently by the NASA Lewis Research Center in support of advanced aeronautical propulsion research. A brief description is provided of the more significant material durability models that were created to describe TMF fatigue resistance of both isotropic and anisotropic superalloys, with and without oxidation resistant coatings. The two most significant crack initiation models are the cyclic damage accumulation model and the total strain version of strainrange partitioning. Unified viscoplastic cyclic constitutive models are also described. A troika of industry, university, and government research organizations contributed to the generation of these analytic models. Based upon current capabilities and established requirements, an attempt is made to project which TMF research activities most likely will impact future generation propulsion systems.

  17. A diffusivity model for predicting VOC diffusion in porous building materials based on fractal theory.

    PubMed

    Liu, Yanfeng; Zhou, Xiaojun; Wang, Dengjia; Song, Cong; Liu, Jiaping

    2015-12-15

    Most building materials are porous media, and the internal diffusion coefficients of such materials have an important influences on the emission characteristics of volatile organic compounds (VOCs). The pore structure of porous building materials has a significant impact on the diffusion coefficient. However, the complex structural characteristics bring great difficulties to the model development. The existing prediction models of the diffusion coefficient are flawed and need to be improved. Using scanning electron microscope (SEM) observations and mercury intrusion porosimetry (MIP) tests of typical porous building materials, this study developed a new diffusivity model: the multistage series-connection fractal capillary-bundle (MSFC) model. The model considers the variable-diameter capillaries formed by macropores connected in series as the main mass transfer paths, and the diameter distribution of the capillary bundles obeys a fractal power law in the cross section. In addition, the tortuosity of the macrocapillary segments with different diameters is obtained by the fractal theory. Mesopores serve as the connections between the macrocapillary segments rather than as the main mass transfer paths. The theoretical results obtained using the MSFC model yielded a highly accurate prediction of the diffusion coefficients and were in a good agreement with the VOC concentration measurements in the environmental test chamber. PMID:26291782

  18. Porous carbon material containing CaO for acidic gas capture: preparation and properties.

    PubMed

    Przepiórski, Jacek; Czyżewski, Adam; Pietrzak, Robert; Toyoda, Masahiro; Morawski, Antoni W

    2013-12-15

    A one-step process for the preparation of CaO-containing porous carbons is described. Mixtures of poly(ethylene terephthalate) with natural limestone were pyrolyzed and thus hybrid sorbents could be easily obtained. The polymeric material and the mineral served as a carbon precursor and CaO delivering agent, respectively. We discuss effects of the preparation conditions and the relative amounts of the raw materials used for the preparations on the porosity of the hybrid products. The micropore areas and volumes of the obtained products tended to decrease with increasing CaO contents. Increase in the preparation temperature entailed a decrease in the micropore volume, whereas the mesopore volume increased. The pore creation mechanism is proposed on the basis of thermogravimetric and temperature-programmed desorption measurements. The prepared CaO-containing porous carbons efficiently captured SO2 and CO2 from air. Washing out of CaO from the hybrid materials was confirmed as a suitable method to obtain highly porous carbon materials.

  19. Enhancing activated-peroxide formulations for porous materials :

    SciTech Connect

    Krauter, Paula; Tucker, Mark D.; Tezak, Matthew S.; Boucher, Raymond

    2012-12-01

    During an urban wide-area incident involving the release of a biological warfare agent, the recovery/restoration effort will require extensive resources and will tax the current capabilities of the government and private contractors. In fact, resources may be so limited that decontamination by facility owners/occupants may become necessary and a simple decontamination process and material should be available for this use. One potential process for use by facility owners/occupants would be a liquid sporicidal decontaminant, such as pHamended bleach or activated-peroxide, and simple application devices. While pH-amended bleach is currently the recommended low-tech decontamination solution, a less corrosive and toxic decontaminant is desirable. The objective of this project is to provide an operational assessment of an alternative to chlorine bleach for low-tech decontamination applications activated hydrogen peroxide. This report provides the methods and results for activatedperoxide evaluation experiments. The results suggest that the efficacy of an activated-peroxide decontaminant is similar to pH-amended bleach on many common materials.

  20. A review on solar cells from Si-single crystals to porous materials and quantum dots

    PubMed Central

    Badawy, Waheed A.

    2013-01-01

    Solar energy conversion to electricity through photovoltaics or to useful fuel through photoelectrochemical cells was still a main task for research groups and developments sectors. In this article we are reviewing the development of the different generations of solar cells. The fabrication of solar cells has passed through a large number of improvement steps considering the technological and economic aspects. The first generation solar cells were based on Si wafers, mainly single crystals. Permanent researches on cost reduction and improved solar cell efficiency have led to the marketing of solar modules having 12–16% solar conversion efficiency. Application of polycrystalline Si and other forms of Si have reduced the cost but on the expense of the solar conversion efficiency. The second generation solar cells were based on thin film technology. Thin films of amorphous Si, CIS (copper–indium–selenide) and t-Si were employed. Solar conversion efficiencies of about 12% have been achieved with a remarkable cost reduction. The third generation solar cells are based on nano-crystals and nano-porous materials. An advanced photovoltaic cell, originally developed for satellites with solar conversion efficiency of 37.3%, based on concentration of the solar spectrum up to 400 suns was developed. It is based on extremely thin concentration cells. New sensitizer or semiconductor systems are necessary to broaden the photo-response in solar spectrum. Hybrids of solar and conventional devices may provide an interim benefit in seeking economically valuable devices. New quantum dot solar cells based on CdSe–TiO2 architecture have been developed. PMID:25750746

  1. A review on solar cells from Si-single crystals to porous materials and quantum dots.

    PubMed

    Badawy, Waheed A

    2015-03-01

    Solar energy conversion to electricity through photovoltaics or to useful fuel through photoelectrochemical cells was still a main task for research groups and developments sectors. In this article we are reviewing the development of the different generations of solar cells. The fabrication of solar cells has passed through a large number of improvement steps considering the technological and economic aspects. The first generation solar cells were based on Si wafers, mainly single crystals. Permanent researches on cost reduction and improved solar cell efficiency have led to the marketing of solar modules having 12-16% solar conversion efficiency. Application of polycrystalline Si and other forms of Si have reduced the cost but on the expense of the solar conversion efficiency. The second generation solar cells were based on thin film technology. Thin films of amorphous Si, CIS (copper-indium-selenide) and t-Si were employed. Solar conversion efficiencies of about 12% have been achieved with a remarkable cost reduction. The third generation solar cells are based on nano-crystals and nano-porous materials. An advanced photovoltaic cell, originally developed for satellites with solar conversion efficiency of 37.3%, based on concentration of the solar spectrum up to 400 suns was developed. It is based on extremely thin concentration cells. New sensitizer or semiconductor systems are necessary to broaden the photo-response in solar spectrum. Hybrids of solar and conventional devices may provide an interim benefit in seeking economically valuable devices. New quantum dot solar cells based on CdSe-TiO2 architecture have been developed.

  2. Advanced Pattern Material for Investment Casting Applications

    SciTech Connect

    F. Douglas Neece Neil Chaudhry

    2006-02-08

    Cleveland Tool and Machine (CTM) of Cleveland, Ohio in conjunction with Harrington Product Development Center (HPDC) of Cincinnati, Ohio have developed an advanced, dimensionally accurate, temperature-stable, energy-efficient and cost-effective material and process to manufacture patterns for the investment casting industry. In the proposed technology, FOPAT (aFOam PATtern material) has been developed which is especially compatible with the investment casting process and offers the following advantages: increased dimensional accuracy; increased temperature stability; lower cost per pattern; less energy consumption per pattern; decreased cost of pattern making equipment; decreased tooling cost; increased casting yield. The present method for investment casting is "the lost wax" process, which is exactly that, the use of wax as a pattern material, which is then melted out or "lost" from the ceramic shell. The molten metal is then poured into the ceramic shell to produce a metal casting. This process goes back thousands of years and while there have been improvements in the wax and processing technology, the material is basically the same, wax. The proposed technology is based upon an established industrial process of "Reaction Injection Molding" (RIM) where two components react when mixed and then "molded" to form a part. The proposed technology has been modified and improved with the needs of investment casting in mind. A proprietary mix of components has been formulated which react and expand to form a foam-like product. The result is an investment casting pattern with smooth surface finish and excellent dimensional predictability along with the other key benefits listed above.

  3. Preparation and application of highly porous aerogel-based bioactive materials in dentistry

    NASA Astrophysics Data System (ADS)

    Kuttor, Andrea; Szalóki, Melinda; Rente, Tünde; Kerényi, Farkas; Bakó, József; Fábián, István; Lázár, István; Jenei, Attila; Hegedüs, Csaba

    2014-03-01

    In this study, the possibility of preparation and application of highly porous silica aerogel-based bioactive materials are presented. The aerogel was combined with hydroxyapatite and β-tricalcium phosphate as bioactive and osteoinductive agents. The porosity of aerogels was in the mesoporous region with a maximum pore diameter of 7.4 and 12.7 nm for the composite materials. The newly developed bioactive materials were characterized by scanning electron microscopy. The in vitro biological effect of these modified surfaces was also tested on SAOS-2 osteogenic sarcoma cells by confocal laser scanning microscopy.

  4. Moisture storage parameters of porous building materials as time-dependent properties

    NASA Astrophysics Data System (ADS)

    Záleská, Martina; Pavlíková, Milena; Pavlík, Zbyšek

    2016-06-01

    Three different types of bricks and two different types of sandstones are studied in terms of measurement moisture storage parameters for over-hygroscopic moisture area using pressure plate device. For researched materials, basic physical properties as bulk density, matrix density and total open porosity are determined. From the obtained data of moisture storage measurement, the water retention curves and curves of degree of saturation in dependence on suction pressure are constructed. Water retention curve (also called suction curve, capillary potential curve, capillary-pressure function and capillary-moisture relationship) is the basic material property used in models for simulation of moisture storage in porous building materials.

  5. High Velocity Impact Interaction of Metal Particles with Porous Heterogeneous Materials with an Inorganic Matrix

    NASA Astrophysics Data System (ADS)

    Glazunov, A. A.; Ishchenko, A. N.; Afanasyeva, S. A.; Belov, N. N.; Burkin, V. V.; Rogaev, K. S.; Tabachenko, A. N.; Khabibulin, M. V.; Yugov, N. T.

    2016-03-01

    A computational-experimental investigation of stress-strain state and fracture of a porous heterogeneous material with an inorganic matrix, used as a thermal barrier coating of flying vehicles, under conditions of a high-velocity impact by a spherical steel projectile imitating a meteorite particle is discussed. Ballistic tests are performed at the velocities about 2.5 km/s. Numerical modeling of the high-velocity impact is described within the framework of a porous elastoplastic model including fracture and different phase states of the materials. The calculations are performed using the Euler and Lagrange numerical techniques for the velocities up to 10 km/s in a complete-space problem statement.

  6. Fly ash porous material using geopolymerization process for high temperature exposure.

    PubMed

    Abdullah, Mohd Mustafa Al Bakri; Jamaludin, Liyana; Hussin, Kamarudin; Bnhussain, Mohamed; Ghazali, Che Mohd Ruzaidi; Ahmad, Mohd Izzat

    2012-01-01

    This paper presents the results of a study on the effect of temperature on geopolymers manufactured using pozzolanic materials (fly ash). In this paper, we report on our investigation of the performance of porous geopolymers made with fly ash after exposure to temperatures from 600 °C up to 1000 °C. The research methodology consisted of pozzolanic materials (fly ash) synthesized with a mixture of sodium hydroxide and sodium silicate solution as an alkaline activator. Foaming agent solution was added to geopolymer paste. The geopolymer paste samples were cured at 60 °C for one day and the geopolymers samples were sintered from 600 °C to 1000 °C to evaluate strength loss due to thermal damage. We also studied their phase formation and microstructure. The heated geopolymers samples were tested by compressive strength after three days. The results showed that the porous geopolymers exhibited strength increases after temperature exposure.

  7. Fly Ash Porous Material using Geopolymerization Process for High Temperature Exposure

    PubMed Central

    Abdullah, Mohd Mustafa Al Bakri; Jamaludin, Liyana; Hussin, Kamarudin; Bnhussain, Mohamed; Ghazali, Che Mohd Ruzaidi; Ahmad, Mohd Izzat

    2012-01-01

    This paper presents the results of a study on the effect of temperature on geopolymers manufactured using pozzolanic materials (fly ash). In this paper, we report on our investigation of the performance of porous geopolymers made with fly ash after exposure to temperatures from 600 °C up to 1000 °C. The research methodology consisted of pozzolanic materials (fly ash) synthesized with a mixture of sodium hydroxide and sodium silicate solution as an alkaline activator. Foaming agent solution was added to geopolymer paste. The geopolymer paste samples were cured at 60 °C for one day and the geopolymers samples were sintered from 600 °C to 1000 °C to evaluate strength loss due to thermal damage. We also studied their phase formation and microstructure. The heated geopolymers samples were tested by compressive strength after three days. The results showed that the porous geopolymers exhibited strength increases after temperature exposure. PMID:22605984

  8. An electrochemical-sensor system for real-time flow measurements in porous materials.

    PubMed

    Bathany, Cédric; Han, Ja-Ryoung; Abi-Samra, Kameel; Takayama, Shuichi; Cho, Yoon-Kyoung

    2015-08-15

    Flow monitoring in porous materials is critical for the engineering of paper-based microfluidic bioassays. Here, we present an electrochemical-sensor system that monitors the liquid flow in porous materials without affecting the real flow in paper-strip samples. The developed microfluidic sensor records an amperometric signal created by the solution movement mediated by paper wicking. This approach allows the in situ monitoring of the different hydrodynamic conditions of a specific paper geometry or composition. In addition, the method proposed in this work was employed to characterise the fluid flow of different nitrocellulose paper strips after oxygen-plasma treatment or dextran coating. The dextran fluid-flow modifiers were further used on the paper strip-based assays as means of signal enhancement. The proposed electrochemical-sensing method offers a valuable alternative to existing optical-based monitoring techniques for flow measurement in paper-based microfluidic systems.

  9. Estimation of moisture transport coefficients in porous materials using experimental drying kinetics

    NASA Astrophysics Data System (ADS)

    Zaknoune, A.; Glouannec, P.; Salagnac, P.

    2012-02-01

    From experimental drying kinetics, an inverse technique is used to evaluate the moisture transport coefficients in building hygroscopic porous materials. Based on the macroscopic approach developed by Whitaker, a one-dimensional mathematical model is developed to predict heat and mass transfers in porous material. The parameters identification is made by the minimisation of the square deviation between numerical and experimental values of the surface temperature and the average moisture content. Two parameters of an exponential function describing the liquid phase transfer and one parameter relative to the diffusion of the vapour phase are identified. To ensure the feasibility of the estimation method, it is initially validated with cellular concrete and applied to lime paste.

  10. Ordered porous mesostructured materials from nanoparticle-block copolymer self-assembly

    DOEpatents

    Warren, Scott; Wiesner, Ulrich; DiSalvo, Jr., Francis J

    2013-10-29

    The invention provides mesostructured materials and methods of preparing mesostructured materials including metal-rich mesostructured nanoparticle-block copolymer hybrids, porous metal-nonmetal nanocomposite mesostructures, and ordered metal mesostructures with uniform pores. The nanoparticles can be metal, metal alloy, metal mixture, intermetallic, metal-carbon, metal-ceramic, semiconductor-carbon, semiconductor-ceramic, insulator-carbon or insulator-ceramic nanoparticles, or combinations thereof. A block copolymer/ligand-stabilized nanoparticle solution is cast, resulting in the formation of a metal-rich (or semiconductor-rich or insulator-rich) mesostructured nanoparticle-block copolymer hybrid. The hybrid is heated to an elevated temperature, resulting in the formation of an ordered porous nanocomposite mesostructure. A nonmetal component (e.g., carbon or ceramic) is then removed to produce an ordered mesostructure with ordered and large uniform pores.

  11. Electrochemical differential photoacoustic cell to study in situ the growing process of porous materials.

    PubMed

    Gutiérrez, Adriana; Giraldo, Jairo; Velázquez-Hernández, Rubén; Mendoza-López, Maria Luisa; Espinosa-Arbeláez, Diego G; del Real, Alicia; Rodríguez-García, Mario E

    2010-01-01

    In order to study in situ the growing process of porous materials, a new electrochemical differential photoacoustic cell (DPC) was developed. This system allows to obtain the thermal signals coming from the growing process of the pores without the external noise component. The DPC is a good system to growth porous silicon and study their growing process with reproducibility. The porous silicon samples were obtained by using electrochemical etching of (100) n-type silicon wafers with different nominal resistivity values in the range of 1-25 Omega cm. The samples were formed in a solution of hydrofluoric acid and ethanol having a composition ratio of 1:1 in volume with etching voltage of 10 V and an etching time of 2 min using back illumination provided by a laser beam with a wavelength of 808 nm. The porous samples were characterized by means of Raman microscopy, x-ray diffraction, and scanning electron microscopy. The crystallite sizes of the samples were obtained through the analysis of the micro-Raman spectra using a phonon confinement model, and the analysis of the x-ray diffractograms.

  12. Indentation Methods in Advanced Materials Research Introduction

    SciTech Connect

    Pharr, George Mathews; Cheng, Yang-Tse; Hutchings, Ian; Sakai, Mototsugu; Moody, Neville; Sundararajan, G.; Swain, Michael V.

    2009-01-01

    Since its commercialization early in the 20th century, indentation testing has played a key role in the development of new materials and understanding their mechanical behavior. Progr3ess in the field has relied on a close marriage between research in the mechanical behavior of materials and contact mechanics. The seminal work of Hertz laid the foundations for bringing these two together, with his contributions still widely utilized today in examining elastic behavior and the physics of fracture. Later, the pioneering work of Tabor, as published in his classic text 'The Hardness of Metals', exapdned this understanding to address the complexities of plasticity. Enormous progress in the field has been achieved in the last decade, made possible both by advances in instrumentation, for example, load and depth-sensing indentation and scanning electron microscopy (SEM) and transmission electron microscopy (TEM) based in situ testing, as well as improved modeling capabilities that use computationally intensive techniques such as finite element analysis and molecular dynamics simulation. The purpose of this special focus issue is to present recent state of the art developments in the field.

  13. Preparation of porous nickel-titania cermets and their application to anode materials

    SciTech Connect

    Taimatsu, H.; Kudo, K.; Kaneko, H.; Matsukaze, N.; Iwata, T.

    1995-12-31

    Porous nickel-titania cermets have been prepared as new-type anode materials for solid oxide fuel cells using the solid-state displacement reaction method. The microstructures of the cermets were interwoven aggregate-type, differently from those of conventional nickel-YSZ cermets: nickel and titania phases three-dimensionally entangled each other. These cermets revealed good properties in compatibility of thermal expansion with YSZ, strength, gas permeation and electrical conduction.

  14. A homochiral metal-organic porous material for enantioselective separation and catalysis

    NASA Astrophysics Data System (ADS)

    Seo, Jung Soo; Whang, Dongmok; Lee, Hyoyoung; Jun, Sung Im; Oh, Jinho; Jeon, Young Jin; Kim, Kimoon

    2000-04-01

    Inorganic zeolites are used for many practical applications that exploit the microporosity intrinsic to their crystal structures. Organic analogues, which are assembled from modular organic building blocks linked through non-covalent interactions, are of interest for similar applications. These range from catalysis, separation and sensor technology to optoelectronics, with enantioselective separation and catalysis being especially important for the chemical and pharmaceutical industries. The modular construction of these analogues allows flexible and rational design, as both the architecture and chemical functionality of the micropores can, in principle, be precisely controlled. Porous organic solids with large voids and high framework stability have been produced, and investigations into the range of accessible pore functionalities have been initiated. For example, catalytically active organic zeolite analogues are known, as are chiral metal-organic open-framework materials. However, the latter are only available as racemic mixtures, or lack the degree of framework stability or void space that is required for practical applications. Here we report the synthesis of a homochiral metal-organic porous material that allows the enantioselective inclusion of metal complexes in its pores and catalyses a transesterification reaction in an enantioselective manner. Our synthesis strategy, which uses enantiopure metal-organic clusters as secondary building blocks, should be readily applicable to chemically modified cluster components and thus provide access to a wide range of porous organic materials suitable for enantioselective separation and catalysis.

  15. Fabrication of interpenetrating polymer network chitosan/gelatin porous materials and study on dye adsorption properties.

    PubMed

    Cui, Li; Xiong, Zihao; Guo, Yi; Liu, Yun; Zhao, Jinchao; Zhang, Chuanjie; Zhu, Ping

    2015-11-01

    One kind of adsorbent based on chitosan and gelatin with interpenetrating polymer networks (IPN) and porous dual structures was prepared using genipin as the cross-linker. These dual structures were demonstrated by means of Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Adsorptions of acid orange II dye from aqueous solution were carried out at different genipin contents, adsorption times and pH values. The results showed that this material was put up the largest adsorption capacity when the genipin content is 0.25 mmol/L, meanwhile, the lower the solution pH value the greater the adsorption capacity. The chitosan/gelatin interpenetrating polymer networks porous material displayed pH-sensitive and rapidly response in adsorption and desorption to pH altered. It is indicated that the cross-linked chitosan/gelatin interpenetrating polymer networks porous material could be used as a recyclable adsorbent in removal or separation of anionic dyes as environmental pH condition changed.

  16. Theoretical and experimental investigation of acoustic streaming in a porous material.

    PubMed

    Poesio, Pietro; Ooms, Gijs; Schraven, Arthur; van der Bas, Fred

    2002-07-01

    An experimental and theoretical investigation of the influence of high-frequency acoustic waves on the flow of a liquid through a porous material has been made. Particular attention was paid to the phenomenon of acoustic streaming of the liquid in the porous material due to the damping of the acoustic waves. The experiments were performed on Berea sandstone cores. Two acoustic horns were used with frequencies of 20 and 40 kHz, and with maximum power output of 2 and 0.7 kW, respectively. A high external pressure was applied in order to avoid cavitation. A microphone was used to measure the damping of the waves in the porous material and also temperature and pressure measurements in the flowing liquid inside the cores were carried out. To model the acoustic streaming effect Darcy's law was extended with a source term representing the momentum transfer from the acoustic waves to the liquid. The model predictions for the pressure distribution inside the core under acoustic streaming conditions are in reasonable agreement with the experimental data.

  17. Porous coordination polymers as novel sorption materials for heat transformation processes.

    PubMed

    Janiak, Christoph; Henninger, Stefan K

    2013-01-01

    Porous coordination polymers (PCPs)/metal-organic frameworks (MOFs) are inorganic-organic hybrid materials with a permanent three-dimensional porous metal-ligand network. PCPs or MOFs are inorganic-organic analogs of zeolites in terms of porosity and reversible guest exchange properties. Microporous water-stable PCPs with high water uptake capacity are gaining attention for low temperature heat transformation applications in thermally driven adsorption chillers (TDCs) or adsorption heat pumps (AHPs). TDCs or AHPs are an alternative to traditional air conditioners or heat pumps operating on electricity or fossil fuels. By using solar or waste heat as the operating energy TDCs or AHPs can significantly help to minimize primary energy consumption and greenhouse gas emissions generated by industrial or domestic heating and cooling processes. TDCs and AHPs are based on the evaporation and consecutive adsorption of coolant liquids, preferably water, under specific conditions. The process is driven and controlled by the microporosity and hydrophilicity of the employed sorption material. Here we summarize the current investigations, developments and possibilities of PCPs/MOFs for use in low-temperature heat transformation applications as alternative materials for the traditional inorganic porous substances like silica gel, aluminophosphates or zeolites.

  18. Limit analysis and homogenization of porous materials with Mohr–Coulomb matrix. Part I: Theoretical formulation

    NASA Astrophysics Data System (ADS)

    Anoukou, K.; Pastor, F.; Dufrenoy, P.; Kondo, D.

    2016-06-01

    The present two-part study aims at investigating the specific effects of Mohr-Coulomb matrix on the strength of ductile porous materials by using a kinematic limit analysis approach. While in the Part II, static and kinematic bounds are numerically derived and used for validation purpose, the present Part I focuses on the theoretical formulation of a macroscopic strength criterion for porous Mohr-Coulomb materials. To this end, we consider a hollow sphere model with a rigid perfectly plastic Mohr-Coulomb matrix, subjected to axisymmetric uniform strain rate boundary conditions. Taking advantage of an appropriate family of three-parameter trial velocity fields accounting for the specific plastic deformation mechanisms of the Mohr-Coulomb matrix, we then provide a solution of the constrained minimization problem required for the determination of the macroscopic dissipation function. The macroscopic strength criterion is then obtained by means of the Lagrangian method combined with Karush-Kuhn-Tucker conditions. After a careful analysis and discussion of the plastic admissibility condition associated to the Mohr-Coulomb criterion, the above procedure leads to a parametric closed-form expression of the macroscopic strength criterion. The latter explicitly shows a dependence on the three stress invariants. In the special case of a friction angle equal to zero, the established criterion reduced to recently available results for porous Tresca materials. Finally, both effects of matrix friction angle and porosity are briefly illustrated and, for completeness, the macroscopic plastic flow rule and the voids evolution law are fully furnished.

  19. Porous coordination polymers as novel sorption materials for heat transformation processes.

    PubMed

    Janiak, Christoph; Henninger, Stefan K

    2013-01-01

    Porous coordination polymers (PCPs)/metal-organic frameworks (MOFs) are inorganic-organic hybrid materials with a permanent three-dimensional porous metal-ligand network. PCPs or MOFs are inorganic-organic analogs of zeolites in terms of porosity and reversible guest exchange properties. Microporous water-stable PCPs with high water uptake capacity are gaining attention for low temperature heat transformation applications in thermally driven adsorption chillers (TDCs) or adsorption heat pumps (AHPs). TDCs or AHPs are an alternative to traditional air conditioners or heat pumps operating on electricity or fossil fuels. By using solar or waste heat as the operating energy TDCs or AHPs can significantly help to minimize primary energy consumption and greenhouse gas emissions generated by industrial or domestic heating and cooling processes. TDCs and AHPs are based on the evaporation and consecutive adsorption of coolant liquids, preferably water, under specific conditions. The process is driven and controlled by the microporosity and hydrophilicity of the employed sorption material. Here we summarize the current investigations, developments and possibilities of PCPs/MOFs for use in low-temperature heat transformation applications as alternative materials for the traditional inorganic porous substances like silica gel, aluminophosphates or zeolites. PMID:23945102

  20. Limit analysis and homogenization of porous materials with Mohr-Coulomb matrix. Part I: Theoretical formulation

    NASA Astrophysics Data System (ADS)

    Anoukou, K.; Pastor, F.; Dufrenoy, P.; Kondo, D.

    2016-06-01

    The present two-part study aims at investigating the specific effects of Mohr-Coulomb matrix on the strength of ductile porous materials by using a kinematic limit analysis approach. While in the Part II, static and kinematic bounds are numerically derived and used for validation purpose, the present Part I focuses on the theoretical formulation of a macroscopic strength criterion for porous Mohr-Coulomb materials. To this end, we consider a hollow sphere model with a rigid perfectly plastic Mohr-Coulomb matrix, subjected to axisymmetric uniform strain rate boundary conditions. Taking advantage of an appropriate family of three-parameter trial velocity fields accounting for the specific plastic deformation mechanisms of the Mohr-Coulomb matrix, we then provide a solution of the constrained minimization problem required for the determination of the macroscopic dissipation function. The macroscopic strength criterion is then obtained by means of the Lagrangian method combined with Karush-Kuhn-Tucker conditions. After a careful analysis and discussion of the plastic admissibility condition associated to the Mohr-Coulomb criterion, the above procedure leads to a parametric closed-form expression of the macroscopic strength criterion. The latter explicitly shows a dependence on the three stress invariants. In the special case of a friction angle equal to zero, the established criterion reduced to recently available results for porous Tresca materials. Finally, both effects of matrix friction angle and porosity are briefly illustrated and, for completeness, the macroscopic plastic flow rule and the voids evolution law are fully furnished.

  1. Advanced Materials in Support of EERE Needs to Advance Clean Energy Technologies Program Implementation

    SciTech Connect

    Liby, Alan L; Rogers, Hiram

    2013-10-01

    The goal of this activity was to carry out program implementation and technical projects in support of the ARRA-funded Advanced Materials in Support of EERE Needs to Advance Clean Energy Technologies Program of the DOE Advanced Manufacturing Office (AMO) (formerly the Industrial Technologies Program (ITP)). The work was organized into eight projects in four materials areas: strategic materials, structural materials, energy storage and production materials, and advanced/field/transient processing. Strategic materials included work on titanium, magnesium and carbon fiber. Structural materials included work on alumina forming austentic (AFA) and CF8C-Plus steels. The advanced batteries and production materials projects included work on advanced batteries and photovoltaic devices. Advanced/field/transient processing included work on magnetic field processing. Details of the work in the eight projects are available in the project final reports which have been previously submitted.

  2. Nitrogen-doped porous hollow carbon sphere-decorated separators for advanced lithium-sulfur batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Zhian; Wang, Guanchao; Lai, Yanqing; Li, Jie; Zhang, Zhiyong; Chen, Wei

    2015-12-01

    Lithium-sulfur (Li-S) batteries have a distinct advantage over other rechargeable battery systems since their high specific energy and low cost. However, the diffusion of polysulfides from cathode to anode leads to poor electrochemical stability of Li-S batteries, which is a main factor that restricts their further development. Herein, for the first time we present a separator with nitrogen-doped porous hollow carbon sphere (NHC) coating, with which Li-S cells enormously improve the utilization of active material and enhance excellent electrochemical performance. An initial discharge capacity of 1656 mAh g-1 (0.2 C) and a low fading rate of 0.11% per cycle within 500 cycles (1 C) are achieved, which ascribe to the chemical and physical adsorption properties of porous and nitrogen-doped NHCs. The NHC-decorated separator is of low cost and can effectively improve energy density of Li-S cells, exhibiting potential for further development of Li-S batteries.

  3. Automatic Structure Analysis in High-Throughput Characterization of Porous Materials.

    PubMed

    Haranczyk, Maciej; Sethian, James A

    2010-11-01

    Inspection of the structure and the void space of a porous material is a critical step in most computational studies involving guest molecules. Some sections of the void space, like inaccessible pockets, have to be identified and blocked in molecular simulations. These pockets are typically detected by visual analysis of the geometry, potential or free energy landscapes, or a histogram of an initial molecular simulation. Such visual analysis is time-consuming and inhibits characterization of large sets of materials required in studies focused on identification of the best materials for a given application. We present an automatic approach that bypasses manual visual analysis of this kind, thereby enabling execution of molecular simulations in an unsupervised, high-throughput manner. In our approach, we used a partial differential equations-based front propagation technique to segment out channels and inaccessible pockets of a periodic unit cell of a material. We cast the problem as a path planning problem in 3D space representing a periodic fragment of porous material, and solve the resulting Eikonal equation by using Fast Marching Methods. One attractive feature of this approach is that the to-be-analyzed data can be of varying types, including, for example, a 3D grid representing the distance to the material's surface, the potential or free energy of a molecule inside the material, or even a histogram (a set of snapshots) from a molecular simulation showing areas which were visited by the molecule during the simulation. PMID:26617098

  4. Determination of water retention in stratified porous materials

    USGS Publications Warehouse

    Constantz, J.

    1995-01-01

    Predicted and measured water-retention values, ??(??), were compared for repacked, stratified core samples consisting of either a sand with a stone-bearing layer or a sand with a clay loam layer in various spatial orientations. Stratified core samples were packed in submersible pressure outflow cells, then water-retention measurements were performed between matric potentials, ??, of 0 to -100 kPa. Predictions of ??(??) were based on a simple volume-averaging model using estimates of the relative fraction and ??(??) values of each textural component within a stratified sample. In general, predicted ??(??) curves resembled measured curves well, except at higher saturations in a sample consisting of a clay loam layer over a sand layer. In this case, the model averaged the air-entry of both materials, while the air-entry of the sample was controlled by the clay loam in contact with the cell's air-pressure inlet. In situ, avenues for air-entry generally exist around clay layers, so that the model should adequately predict air-entry for stratified formations regardless of spatial orientation of fine versus coarse layers. Agreement between measured and predicted volumetric water contents, ??, was variable though encouraging, with mean differences between measured and predicted ?? values in the range of 10%. Differences in ?? of this magnitude are expected due to variability in pore structure between samples, and do not indicate inherent problems with the volume averaging model. This suggets that explicit modeling of stratified formations through detailed characterization of the stratigraphy has the potential of yielding accurate ??(??) values. However, hydraulic-equilibration times were distinctly different for each variation in spatial orientation of textural layering, indicating that transient behavior during drainage in stratified formations is highly sensitive to the stratigraphic sequence of textural components, as well as the volume fraction of each textural

  5. Method and apparatus for measuring surface changes, in porous materials, using multiple differently-configured acoustic sensors

    DOEpatents

    Hietala, Susan Leslie; Hietala, Vincent Mark; Tigges, Chris Phillip

    2001-01-01

    A method and apparatus for measuring surface changes, such as mass uptake at various pressures, in a thin-film material, in particular porous membranes, using multiple differently-configured acoustic sensors.

  6. Analytical Fractal Model for Calculating Effective Thermal Conductivity of the Fibrous Porous Materials.

    PubMed

    Kan, An-Kang; Cao, Dan; Zhang, Xue-Lai

    2015-04-01

    Accurately predicting the effective thermal conductivity of the fibrous materials is highly desirable but remains to be a challenging work. In this paper, the microstructure of the porous fiber materials is analyzed, approximated and modeled on basis of the statistical self-similarity of fractal theory. A fractal model is presented to accurately calculate the effective thermal conductivity of fibrous porous materials. Taking the two-phase heat transfer effect into account, the existing statistical microscopic geometrical characteristics are analyzed and the Hertzian Contact solution is introduced to calculate the thermal resistance of contact points. Using the fractal method, the impacts of various factors, including the porosity, fiber orientation, fractal diameter and dimension, rarified air pressure, bulk thermal conductivity coefficient, thickness and environment condition, on the effective thermal conductivity, are analyzed. The calculation results show that the fiber orientation angle caused the material effective thermal conductivity to be anisotropic, and normal distribution is introduced into the mathematic function. The effective thermal conductivity of fibrous material increases with the fiber fractal diameter, fractal dimension and rarefied air pressure within the materials, but decreases with the increase of vacancy porosity.

  7. Advanced Industrial Materials Program. Annual progress report, FY 1993

    SciTech Connect

    Stooksbury, F.

    1994-06-01

    Mission of the AIM program is to commercialize new/improved materials and materials processing methods that will improve energy efficiency, productivity, and competitiveness. Program investigators in the DOE national laboratories are working with about 100 companies, including 15 partners in CRDAs. Work is being done on intermetallic alloys, ceramic composites, metal composites, polymers, engineered porous materials, and surface modification. The program supports other efforts in the Office of Industrial Technologies to assist the energy-consuming process industries. The aim of the AIM program is to bring materials from basic research to industrial application to strengthen the competitive position of US industry and save energy.

  8. Small angle scattering methods to study porous materials under high uniaxial strain

    SciTech Connect

    Le Floch, Sylvie Balima, Félix; Pischedda, Vittoria; Legrand, Franck; San-Miguel, Alfonso

    2015-02-15

    We developed a high pressure cell for the in situ study of the porosity of solids under high uniaxial strain using neutron small angle scattering. The cell comprises a hydraulically actioned piston and a main body equipped with two single-crystal sapphire windows allowing for the neutron scattering of the sample. The sample cavity is designed to allow for a large volume variation as expected when compressing highly porous materials. We also implemented a loading protocol to adapt an existing diamond anvil cell for the study of porous materials by X-ray small angle scattering under high pressure. The two techniques are complementary as the radiation beam and the applied pressure are in one case perpendicular to each other (neutron cell) and in the other case parallel (X-ray cell). We will illustrate the use of these two techniques in the study of lamellar porous systems up to a maximum pressure of 0.1 GPa and 0.3 GPa for the neutron and X-ray cells, respectively. These devices allow obtaining information on the evolution of porosity with pressure in the pore dimension subdomain defined by the wave-numbers explored in the scattering process. The evolution with the applied load of such parameters as the fractal dimension of the pore-matrix interface or the apparent specific surface in expanded graphite and in expanded vermiculite is used to illustrate the use of the high pressure cells.

  9. Use of a porous material description of forests in infrasonic propagation algorithms.

    PubMed

    Swearingen, Michelle E; White, Michael J; Ketcham, Stephen A; McKenna, Mihan H

    2013-10-01

    Infrasound can propagate very long distances and remain at measurable levels. As a result infrasound sensing is used for remote monitoring in many applications. At local ranges, on the order of 10 km, the influence of the presence or absence of forests on the propagation of infrasonic signals is considered. Because the wavelengths of interest are much larger than the scale of individual components, the forest is modeled as a porous material. This approximation is developed starting with the relaxation model of porous materials. This representation is then incorporated into a Crank-Nicholson method parabolic equation solver to determine the relative impacts of the physical parameters of a forest (trunk size and basal area), the presence of gaps/trees in otherwise continuous forest/open terrain, and the effects of meteorology coupled with the porous layer. Finally, the simulations are compared to experimental data from a 10.9 kg blast propagated 14.5 km. Comparison to the experimental data shows that appropriate inclusion of a forest layer along the propagation path provides a closer fit to the data than solely changing the ground type across the frequency range from 1 to 30 Hz. PMID:24116403

  10. Small angle scattering methods to study porous materials under high uniaxial strain.

    PubMed

    Le Floch, Sylvie; Balima, Félix; Pischedda, Vittoria; Legrand, Franck; San-Miguel, Alfonso

    2015-02-01

    We developed a high pressure cell for the in situ study of the porosity of solids under high uniaxial strain using neutron small angle scattering. The cell comprises a hydraulically actioned piston and a main body equipped with two single-crystal sapphire windows allowing for the neutron scattering of the sample. The sample cavity is designed to allow for a large volume variation as expected when compressing highly porous materials. We also implemented a loading protocol to adapt an existing diamond anvil cell for the study of porous materials by X-ray small angle scattering under high pressure. The two techniques are complementary as the radiation beam and the applied pressure are in one case perpendicular to each other (neutron cell) and in the other case parallel (X-ray cell). We will illustrate the use of these two techniques in the study of lamellar porous systems up to a maximum pressure of 0.1 GPa and 0.3 GPa for the neutron and X-ray cells, respectively. These devices allow obtaining information on the evolution of porosity with pressure in the pore dimension subdomain defined by the wave-numbers explored in the scattering process. The evolution with the applied load of such parameters as the fractal dimension of the pore-matrix interface or the apparent specific surface in expanded graphite and in expanded vermiculite is used to illustrate the use of the high pressure cells.

  11. Use of a porous material description of forests in infrasonic propagation algorithms.

    PubMed

    Swearingen, Michelle E; White, Michael J; Ketcham, Stephen A; McKenna, Mihan H

    2013-10-01

    Infrasound can propagate very long distances and remain at measurable levels. As a result infrasound sensing is used for remote monitoring in many applications. At local ranges, on the order of 10 km, the influence of the presence or absence of forests on the propagation of infrasonic signals is considered. Because the wavelengths of interest are much larger than the scale of individual components, the forest is modeled as a porous material. This approximation is developed starting with the relaxation model of porous materials. This representation is then incorporated into a Crank-Nicholson method parabolic equation solver to determine the relative impacts of the physical parameters of a forest (trunk size and basal area), the presence of gaps/trees in otherwise continuous forest/open terrain, and the effects of meteorology coupled with the porous layer. Finally, the simulations are compared to experimental data from a 10.9 kg blast propagated 14.5 km. Comparison to the experimental data shows that appropriate inclusion of a forest layer along the propagation path provides a closer fit to the data than solely changing the ground type across the frequency range from 1 to 30 Hz.

  12. Europium (III) Organic Complexes in Porous Boron Nitride Microfibers: Efficient Hybrid Luminescent Material

    PubMed Central

    Lin, Jing; Feng, Congcong; He, Xin; Wang, Weijia; Fang, Yi; Liu, Zhenya; Li, Jie; Tang, Chengchun; Huang, Yang

    2016-01-01

    We report the design and synthesis of a novel kind of organic-inorganic hybrid material via the incorporation of europium (III) β-diketonate complexes (Eu(TTA)3, TTA = 2-thenoyltrifluoroacetone) into one-dimensional (1D) porous boron nitride (BN) microfibers. The developed Eu(TTA)3@BN hybrid composites with typical 1D fibrous morphology exhibit bright visible red-light emission on UV illumination. The confinement of Eu(TTA)3 within pores of BN microfibers not only decreases the aggregation-caused quenching in solid Eu(TTA)3, but also improves their thermal stabilities. Moreover, The strong interactions between Eu(TTA)3 and porous BN matrix result in an interesting energy transfer process from BN host to TTA ligand and TTA ligand to Eu3+ ions, leading to the remarkable increase of red emission. The synthetic approach should be a very promising strategy which can be easily expanded to other hybrid luminescent materials based on porous BN. PMID:27687246

  13. Reliability Testing of Advanced Interconnect Materials

    NASA Astrophysics Data System (ADS)

    Keller, R. R.; Strus, M. C.; Chiaramonti, A. N.; Kim, Y. L.; Jung, Y. J.; Read, D. T.

    2011-11-01

    We describe the development of electrical test methods to evaluate damage that determines reliability in advanced, small-scale conductors, including damascene copper and aligned carbon nanotube networks. Rapid thermal cycling induced during high-current AC stressing provides a means for measuring lifetimes associated with cyclic plasticity and/or diffusive damage in damascene copper. The specific type of damage that develops depends on the line geometry and the nature of the stress state induced within the lines during cycling. Voids form in both fully passivated and partially passivated lines under high levels of hydrostatic tension. Dislocation activity takes place in partially passivated lines in the presence of high shears. High-current DC stressing provides a means for evaluating the fabrication quality of aligned carbon nanotube (CNT) networks, in what we believe to be the first lifetime degradation tests of such materials. While classic electromigration is unlikely in nanocarbon, we observed through resistance changes two forms of degradation that we believe are tied to the nanotube packing and resulting conduction path density through the network: a gradual build-up of damage, and a more abrupt, unpredictable form of damage accumulation, which may be linked to sudden changes in network morphology due to stressing.

  14. Advanced materials and nanotechnology for drug delivery.

    PubMed

    Yan, Li; Yang, Yang; Zhang, Wenjun; Chen, Xianfeng

    2014-08-20

    Many biological barriers are of great importance. For example, stratum corneum, the outmost layer of skin, effectively protects people from being invaded by external microorganisms such as bacteria and viruses. Cell membranes help organisms maintain homeostasis by controlling substances to enter and leave cells. However, on the other hand, these biological barriers seriously restrict drug delivery. For instance, stratum corneum has a very dense structure and only allows very small molecules with a molecular weight of below 500 Da to permeate whereas most drug molecules are much larger than that. A wide variety of drugs including genes needs to enter cells for proper functioning but cell membranes are not permeable to them. To overcome these biological barriers, many drug-delivery routes are being actively researched and developed. In this research news, we will focus on two advanced materials and nanotechnology approaches for delivering vaccines through the skin for painless and efficient immunization and transporting drug molecules to cross cell membranes for high-throughput intracellular delivery.

  15. Hierarchically porous materials from layer-by-layer photopolymerization of high internal phase emulsions.

    PubMed

    Sušec, Maja; Ligon, Samuel Clark; Stampfl, Jürgen; Liska, Robert; Krajnc, Peter

    2013-06-13

    A combination of high internal phase emulsion (HIPE) templating and additive manufacturing technology (AMT) is applied for creating hierarchical porosity within an acrylate and acrylate/thiol-based polymer network. The photopolymerizable formulation is optimized to produce emulsions with a volume fraction of droplet phase greater than 80 vol%. Kinetic stability of the emulsions is sufficient enough to withstand in-mold curing or computer-controlled layer-by-layer stereolithography without phase separation. By including macroscale cellular cavities within the build file, a level of controlled porosity is created simultaneous to the formation of the porous microstructure of the polyHIPE. The hybrid HIPE-AMT technique thus provides hierarchically porous materials with mechanical properties tailored by the addition of thiol chain transfer agent.

  16. Sponge-Like Behaviour in Isoreticular Cu(Gly-His-X) Peptide-Based Porous Materials.

    PubMed

    Martí-Gastaldo, Carlos; Warren, John E; Briggs, Michael E; Armstrong, Jayne A; Thomas, K Mark; Rosseinsky, Matthew J

    2015-11-01

    We report two isoreticular 3D peptide-based porous frameworks formed by coordination of the tripeptides Gly-L-His-Gly and Gly-L-His-L-Lys to Cu(II) which display sponge-like behaviour. These porous materials undergo structural collapse upon evacuation that can be reversed by exposure to water vapour, which permits recovery of the original open channel structure. This is further confirmed by sorption studies that reveal that both solids exhibit selective sorption of H2 O while CO2 adsorption does not result in recovery of the original structures. We also show how the pendant aliphatic amine chains, present in the framework from the introduction of the lysine amino acid in the peptidic backbone, can be post-synthetically modified to produce urea-functionalised networks by following methodologies typically used for metal-organic frameworks built from more rigid "classical" linkers. PMID:26406996

  17. Sponge-Like Behaviour in Isoreticular Cu(Gly-His-X) Peptide-Based Porous Materials

    PubMed Central

    Martí-Gastaldo, Carlos; Warren, John E; Briggs, Michael E; Armstrong, Jayne A; Thomas, K Mark; Rosseinsky, Matthew J

    2015-01-01

    We report two isoreticular 3D peptide-based porous frameworks formed by coordination of the tripeptides Gly-l-His-Gly and Gly-l-His-l-Lys to CuII which display sponge-like behaviour. These porous materials undergo structural collapse upon evacuation that can be reversed by exposure to water vapour, which permits recovery of the original open channel structure. This is further confirmed by sorption studies that reveal that both solids exhibit selective sorption of H2O while CO2 adsorption does not result in recovery of the original structures. We also show how the pendant aliphatic amine chains, present in the framework from the introduction of the lysine amino acid in the peptidic backbone, can be post-synthetically modified to produce urea-functionalised networks by following methodologies typically used for metal–organic frameworks built from more rigid “classical” linkers. PMID:26406996

  18. Superior supercapacitor electrode material from hydrazine hydrate modified porous polyacrylonitrile fiber

    NASA Astrophysics Data System (ADS)

    Li, Ying; Lu, Chunxiang; Wang, Junzhong; Yan, Hua; Zhang, Shouchun

    2016-03-01

    A hierarchical porous carbon fiber with high nitrogen doping was fabricated for high-performance supercapacitor. For the purpose of high nitrogen retention, the porous polyacrylonitrile fiber was treated by hydrazine hydrate, and then underwent pre-oxidation, carbonization, and activation in sequence. The resulted material exhibited high nitrogen content of 7.82 at.%, large specific surface area of 1963.3m2 g‑1, total pore volume of 1.523cm3 g‑1, and the pores with size range of 1-4nm were account for 49.1%. Due to these features, the high reversible capacitance of 415F g‑1 and the good performance in heavy load discharge were obtained. In addition, the amazing cyclability was observed after 10,000 circles without capacitance fading.

  19. Advanced High-Temperature Engine Materials Technology Progresses

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The objective of the Advanced High Temperature Engine Materials Technology Program (HITEMP) at the NASA Lewis Research Center is to generate technology for advanced materials and structural analysis that will increase fuel economy, improve reliability, extend life, and reduce operating costs for 21st century civil propulsion systems. The primary focus is on fan and compressor materials (polymer-matrix composites - PMC's), compressor and turbine materials (superalloys, and metal-matrix and intermetallic-matrix composites - MMC's and IMC's), and turbine materials (ceramic-matrix composites - CMC's). These advanced materials are being developed in-house by Lewis researchers and on grants and contracts.

  20. Model for the interpretation of nuclear magnetic resonance relaxometry of hydrated porous silicate materials.

    PubMed

    Faux, D A; Cachia, S-H P; McDonald, P J; Bhatt, J S; Howlett, N C; Churakov, S V

    2015-03-01

    Nuclear magnetic resonance (NMR) relaxation experimentation is an effective technique for probing the dynamics of proton spins in porous media, but interpretation requires the application of appropriate spin-diffusion models. Molecular dynamics (MD) simulations of porous silicate-based systems containing a quasi-two-dimensional water-filled pore are presented. The MD simulations suggest that the residency time of the water on the pore surface is in the range 0.03-12 ns, typically 2-5 orders of magnitude less than values determined from fits to experimental NMR measurements using the established surface-layer (SL) diffusion models of Korb and co-workers [Phys. Rev. E 56, 1934 (1997)]. Instead, MD identifies four distinct water layers in a tobermorite-based pore containing surface Ca2+ ions. Three highly structured water layers exist within 1 nm of the surface and the central region of the pore contains a homogeneous region of bulklike water. These regions are referred to as layer 1 and 2 (L1, L2), transition layer (TL), and bulk (B), respectively. Guided by the MD simulations, a two-layer (2L) spin-diffusion NMR relaxation model is proposed comprising two two-dimensional layers of slow- and fast-moving water associated with L2 and layers TL+B, respectively. The 2L model provides an improved fit to NMR relaxation times obtained from cementitious material compared to the SL model, yields diffusion correlation times in the range 18-75 ns and 28-40 ps in good agreement with MD, and resolves the surface residency time discrepancy. The 2L model, coupled with NMR relaxation experimentation, provides a simple yet powerful method of characterizing the dynamical properties of proton-bearing porous silicate-based systems such as porous glasses, cementitious materials, and oil-bearing rocks. PMID:25871114

  1. From spent Mg/Al layered double hydroxide to porous carbon materials.

    PubMed

    Laipan, Minwang; Zhu, Runliang; Chen, Qingze; Zhu, Jianxi; Xi, Yunfei; Ayoko, Godwin A; He, Hongping

    2015-12-30

    Adsorption has been considered as an efficient method for the treatment of dye effluents, but proper disposal of the spent adsorbents is still a challenge. This work attempts to provide a facile method to reutilize the spent Mg/Al layered double hydroxide (Mg/Al-LDH) after the adsorption of orange II (OII). Herein, the spent hybrid was carbonized under the protection of nitrogen, and then washed with acid to obtain porous carbon materials. Thermogravimetric analysis results suggested that the carbonization could be well achieved above 600°C, as mass loss of the spent hybrid gradually stabilized. Therefore, the carbonization process was carried out at 600, 800, and 1000°C, respectively. Scanning electron microscope showed that the obtained carbon materials possessed a crooked flaky morphology. Nitrogen adsorption-desorption results showed that the carbon materials had large BET surface area and pore volume, e.g., 1426 m(2)/g and 1.67 cm(3)/g for the sample carbonized at 800°C. Moreover, the pore structure and surface chemistry compositions were tunable, as they were sensitive to the temperature. Toluene adsorption results demonstrated that the carbon materials had high efficiency in toluene removal. This work provided a facile approach for synthesizing porous carbon materials using spent Mg/Al-LDH.

  2. From spent Mg/Al layered double hydroxide to porous carbon materials.

    PubMed

    Laipan, Minwang; Zhu, Runliang; Chen, Qingze; Zhu, Jianxi; Xi, Yunfei; Ayoko, Godwin A; He, Hongping

    2015-12-30

    Adsorption has been considered as an efficient method for the treatment of dye effluents, but proper disposal of the spent adsorbents is still a challenge. This work attempts to provide a facile method to reutilize the spent Mg/Al layered double hydroxide (Mg/Al-LDH) after the adsorption of orange II (OII). Herein, the spent hybrid was carbonized under the protection of nitrogen, and then washed with acid to obtain porous carbon materials. Thermogravimetric analysis results suggested that the carbonization could be well achieved above 600°C, as mass loss of the spent hybrid gradually stabilized. Therefore, the carbonization process was carried out at 600, 800, and 1000°C, respectively. Scanning electron microscope showed that the obtained carbon materials possessed a crooked flaky morphology. Nitrogen adsorption-desorption results showed that the carbon materials had large BET surface area and pore volume, e.g., 1426 m(2)/g and 1.67 cm(3)/g for the sample carbonized at 800°C. Moreover, the pore structure and surface chemistry compositions were tunable, as they were sensitive to the temperature. Toluene adsorption results demonstrated that the carbon materials had high efficiency in toluene removal. This work provided a facile approach for synthesizing porous carbon materials using spent Mg/Al-LDH. PMID:26257095

  3. Hierarchical ZnO-Ag-C composite porous microspheres with superior electrochemical properties as anode materials for lithium ion batteries.

    PubMed

    Xie, Qingshui; Ma, Yating; Zeng, Deqian; Zhang, Xiaoqiang; Wang, Laisen; Yue, Guanghui; Peng, Dong-Liang

    2014-11-26

    Hierarchical ZnO-Ag-C composite porous microspheres are successfully synthesized by calcination of the preproduced zinc-silver citrate porous microspheres in argon. The carbon derives from the in situ carbonization of carboxylic acid groups in zinc-silver citrate during annealing treatment. The average particle size of ZnO-Ag-C composite porous microspheres is approximate 1.5 μm. When adopted as the electrode materials in lithium ion batteries, the obtained composite porous microspheres display high specific capacity, excellent cyclability, and good rate capability. A discharge capacity as high as 729 mA h g(-1) can be retained after 200 cycles at 100 mA g(-1). The excellent electrochemical properties of ZnO-Ag-C are ascribed to its unique hierarchical porous configuration as well as the modification of silver and carbon.

  4. Stability of quasi-steady deflagrations in confined porous energetic materials

    SciTech Connect

    Alexander M. Telengator; Stephen B. Margolis; Forman A. Williams

    2000-03-01

    Previous analyses have shown that unconfined deflagrations propagating through both porous and nonporous energetic materials can exhibit a thermal/diffusive instability that corresponds to the onset of various oscillatory modes of combustion. For porous materials, two-phase-flow effects, associated with the motion of the gas products relative to the condensed material, play a significant role that can shift stability boundaries with respect to those associated with the nonporous problem. In the present work, additional significant effects are shown to be associated with confinement, which produces an overpressure in the burned-gas region that leads to reversal of the gas flow and hence partial permeation of the hot gases into the unburned porous material. This results in a superadiabatic effect that increases the combustion temperature and, consequently, the burning rate. Under the assumption of gas-phase quasi-steadiness, an asymptotic model is presented that facilitates a perturbation analysis of both the basic solution, corresponding to a steadily propagating planar combustion wave, and its stability. The neutral stability boundaries collapse to the previous results in the absence of confinement, but different trends arising from the presence of the gas-permeation layer are predicted for the confined problem. Whereas two-phase-flow effects are generally destabilizing in the unconfined geometry, the effects of increasing overpressure and hence combustion temperature associated with confinement are shown to be generally stabilizing with respect to thermal/diffusive instability, analogous to the effects of decreasing heat losses on combustion temperature and stability in single-phase deflagrations.

  5. Ignition analysis of a porous energetic material. 2. Ignition at a closed heated end

    SciTech Connect

    Alexander M. Telegentor; Stephen B. Margolis; Forman A. Williams

    1998-11-01

    A continuation of an ignition analysis for porous energetic materials subjected to a constant energy flux is presented. In the first part, the analysis was developed for the case of an open-end, semi-infinite material such that gas flow, generated by thermal expansion, flowed out of the porous solid, thereby removing energy from the system. In the present study, the case of a closed end is considered, and thus the thermally-induced gas flow is now directed into the solid. In these studies, an asymptotic perturbation analysis, based on the smallness of the gas-to-solid density ratio and the largeness of the activation energy, is utilized to describe the inert and transition stages leading to thermal runaway. In both cases it is found that the effects of porosity provide a leading-order reduction in the time to ignition relative to that for the nonporous problem, arising from the reduced amount of solid material that must be heated and the difference in thermal conductivities of the solid and gaseous phases. A correction to the leading-order ignition-delay time, however, is provided by the convective flow of gas through the solid, and the sign of this correction is shown to depend on the direction of the gas flow. Thus, gas flowing out of an open-end solid was previously shown to give a positive correction to the leading-order time to ignition. Here, however, it is demonstrated that when the flow of gas is directed into the porous solid, the relative transport effects associated with the gas flow serve to preheat the material, resulting in a negative correction and hence a decrease in the ignition-delay time.

  6. High-intensity sound in air saturated fibrous bulk porous materials

    NASA Technical Reports Server (NTRS)

    Kuntz, H. L., II

    1982-01-01

    The interaction high-intensity sound with bulk porous materials in porous materials including Kevlar 29 is reported. The nonlinear behavior of the materials was described by dc flow resistivity tests. Then acoustic propagation and reflection were measured and small signal broadband measurements of phase speed and attenuation were carried out. High-intensity tests were made with 1, 2, and 3 kHz tone bursts to measure harmonic generation and extra attenuation of the fundamental. Small signal standing wave tests measured impedence between 0.1 and 3.5 kHz. High level tests with single cycle tone bursts at 1 to 4 kHz show that impedance increases with intensity. A theoretical analysis is presented for high-porosity, rigid-frame, isothermal materials. One dimensional equations of motion are derived and solved by perturbation. The experiments show that there is excess attenuation of the fundamental component and in some cases a close approach to saturation. A separate theoretical model, developed to explain the excess attenuation, yields predictions that are in good agreement with the measurements. Impedance and attenuation at high intensities are modeled.

  7. A thermal porosimetry method to estimate pore size distribution in highly porous insulating materials.

    PubMed

    Félix, V; Jannot, Y; Degiovanni, A

    2012-05-01

    Standard pore size determination methods such as mercury porosimetry, nitrogen sorption, microscopy, or x-ray tomography are not always applicable to highly porous, low density, and thus very fragile materials. For this kind of materials, a method based on thermal characterization is proposed. Indeed, the thermal conductivity of a highly porous and insulating medium is significantly dependent on the thermal conductivity of the interstitial gas that depends on both gas pressure and size of the considered pore (Knudsen effect). It is also possible to link the pore size with the thermal conductivity of the medium. Thermal conductivity measurements are realized on specimens placed in an enclosure where the air pressure is successively set to different values varying from 10(-1) to 10(5) Pa. Knowing the global porosity ratio, an effective thermal conductivity model for a two-phase air-solid material based on a combined serial-parallel model is established. Pore size distribution can be identified by minimizing the sum of the quadratic differences between measured values and modeled ones. The results of the estimation process are the volume fractions of the chosen ranges of pore size. In order to validate the method, measurements done on insulating materials are presented. The results are discussed and show that pore size distribution estimated by the proposed method is coherent. PMID:22667640

  8. A thermal porosimetry method to estimate pore size distribution in highly porous insulating materials

    NASA Astrophysics Data System (ADS)

    Félix, V.; Jannot, Y.; Degiovanni, A.

    2012-05-01

    Standard pore size determination methods such as mercury porosimetry, nitrogen sorption, microscopy, or x-ray tomography are not always applicable to highly porous, low density, and thus very fragile materials. For this kind of materials, a method based on thermal characterization is proposed. Indeed, the thermal conductivity of a highly porous and insulating medium is significantly dependent on the thermal conductivity of the interstitial gas that depends on both gas pressure and size of the considered pore (Knudsen effect). It is also possible to link the pore size with the thermal conductivity of the medium. Thermal conductivity measurements are realized on specimens placed in an enclosure where the air pressure is successively set to different values varying from 10-1 to 105 Pa. Knowing the global porosity ratio, an effective thermal conductivity model for a two-phase air-solid material based on a combined serial-parallel model is established. Pore size distribution can be identified by minimizing the sum of the quadratic differences between measured values and modeled ones. The results of the estimation process are the volume fractions of the chosen ranges of pore size. In order to validate the method, measurements done on insulating materials are presented. The results are discussed and show that pore size distribution estimated by the proposed method is coherent.

  9. A thermal porosimetry method to estimate pore size distribution in highly porous insulating materials

    SciTech Connect

    Felix, V.; Jannot, Y.; Degiovanni, A.

    2012-05-15

    Standard pore size determination methods such as mercury porosimetry, nitrogen sorption, microscopy, or x-ray tomography are not always applicable to highly porous, low density, and thus very fragile materials. For this kind of materials, a method based on thermal characterization is proposed. Indeed, the thermal conductivity of a highly porous and insulating medium is significantly dependent on the thermal conductivity of the interstitial gas that depends on both gas pressure and size of the considered pore (Knudsen effect). It is also possible to link the pore size with the thermal conductivity of the medium. Thermal conductivity measurements are realized on specimens placed in an enclosure where the air pressure is successively set to different values varying from 10{sup -1} to 10{sup 5} Pa. Knowing the global porosity ratio, an effective thermal conductivity model for a two-phase air-solid material based on a combined serial-parallel model is established. Pore size distribution can be identified by minimizing the sum of the quadratic differences between measured values and modeled ones. The results of the estimation process are the volume fractions of the chosen ranges of pore size. In order to validate the method, measurements done on insulating materials are presented. The results are discussed and show that pore size distribution estimated by the proposed method is coherent.

  10. A novel nano-porous alumina biomaterial with potential for loading with bioactive materials.

    PubMed

    Walpole, Andrew R; Xia, Zhidao; Wilson, Crispian W; Triffitt, James T; Wilshaw, Peter R

    2009-07-01

    Nano-porous alumina, with the potential for being loaded with bioactive materials, has been proposed as a novel material for coating implants. In this study, the shear strength of the interface between such nano-porous anodic aluminium oxide (AAO) coatings and titanium substrates, their biocompatibility, and their potential for pore loading have been investigated. An interface shear strength in excess of 29 MPa was obtained which is comparable with that of conventional plasma sprayed hydroxyapatite implant coatings. The viability and differentiation of MG63 osteoblastic cells co-cultured on the coating was found to be broadly comparable to that of similar cells co-cultured on conventional bioinert implant materials such as titanium and fully dense alumina. Extensive pore loading with silica nano-particles of different sizes and in different combinations was demonstrated throughout the thickness of AAO layers 1 microm and 60 microm thick. This work has demonstrated, that with suitable choice of pore filling materials, this novel coating might simultaneously combat infection, encourage bone regeneration, and secure fixation of the implant to bone.

  11. A 3D Porous Architecture of Si/graphene Nanocomposite as High-performance Anode Materials for Li-ion Batteries

    SciTech Connect

    Xin X.; Zhu Y.; Zhou, X.; Wang, F.; Yao, X.; Xu, X.; Liu, Z.

    2012-04-28

    A 3D porous architecture of Si/graphene nanocomposite has been rationally designed and constructed through a series of controlled chemical processes. In contrast to random mixture of Si nanoparticles and graphene nanosheets, the porous nanoarchitectured composite has superior electrochemical stability because the Si nanoparticles are firmly riveted on the graphene nanosheets through a thin SiO{sub x} layer. The 3D graphene network enhances electrical conductivity, and improves rate performance, demonstrating a superior rate capability over the 2D nanostructure. This 3D porous architecture can deliver a reversible capacity of {approx}900 mA h g{sup -1} with very little fading when the charge rates change from 100 mA g{sup -1} to 1 A g{sup -1}. Furthermore, the 3D nanoarchitechture of Si/graphene can be cycled at extremely high Li{sup +} extraction rates, such as 5 A g{sup -1} and 10 A g{sup -1}, for over than 100 times. Both the highly conductive graphene network and porous architecture are considered to contribute to the remarkable rate capability and cycling stability, thereby pointing to a new synthesis route to improving the electrochemical performances of the Si-based anode materials for advanced Li-ion batteries.

  12. Porous Materials with Tunable Structure and Mechanical Properties via Templated Layer-by-Layer Assembly.

    PubMed

    Ziminska, Monika; Dunne, Nicholas; Hamilton, Andrew R

    2016-08-31

    The deposition of stiff and strong coatings onto porous templates offers a novel strategy for fabricating macroscale materials with controlled architectures at the micro- and nanoscale. Here, layer-by-layer assembly is utilized to fabricate nanocomposite-coated foams with highly customizable properties by depositing polymer-nanoclay coatings onto open-cell foam templates. The compressive mechanical behavior of these materials evolves in a predictable manner that is qualitatively captured by scaling laws for the mechanical properties of cellular materials. The observed and predicted properties span a remarkable range of density-stiffness space, extending from regions of very soft elastomer foams to very stiff, lightweight honeycomb and lattice materials. PMID:27513218

  13. Infiltrating sulfur into a highly porous carbon sphere as cathode material for lithium–sulfur batteries

    SciTech Connect

    Zhao, Xiaohui; Kim, Dul-Sun; Ahn, Hyo-Jun; Kim, Ki-Won; Cho, Kwon-Koo; Ahn, Jou-Hyeon

    2014-10-15

    Highlights: • A highly porous carbon (HPC) with regular spherical morphology was synthesized. • Sulfur/HPC composites were prepared by melt–diffusion method. • Sulfur/HPC composites showed improved cyclablity and long-term cycle life. - Abstract: Sulfur composite material with a highly porous carbon sphere as the conducting container was prepared. The highly porous carbon sphere was easily synthesized with resorcinol–formaldehyde precursor as the carbon source. The morphology of the carbon was observed with field emission scanning electron microscope and transmission electron microscope, which showed a well-defined spherical shape. Brunauer–Emmett–Teller analysis indicated that it possesses a high specific surface area of 1563 m{sup 2} g{sup −1} and a total pore volume of 2.66 cm{sup 3} g{sup −1} with a bimodal pore size distribution, which allow high sulfur loading and easy transportation of lithium ions. Sulfur carbon composites with varied sulfur contents were prepared by melt–diffusion method and lithium sulfur cells with the sulfur composites showed improved cyclablity and long-term cycle life.

  14. Porous silicon as a potential electrode material in a nerve repair setting: Tissue reactions.

    PubMed

    Johansson, Fredrik; Wallman, Lars; Danielsen, Nils; Schouenborg, Jens; Kanje, Martin

    2009-07-01

    We compared porous silicon (pSi) with smooth Si as chip-implant surfaces in a nerve regeneration setting. Silicon chips can be used for recording neural activity and are potential nerve interface devices. A silicon chip with one smooth and one porous side inserted into a tube was used to bridge a 5 mm defect in rat sciatic nerve. Six or 12 weeks later, new nerve structures surrounded by a perineurium-like capsule had formed on each side of the chip. The number of regenerated nerve fibers did not differ on either side of the chip as shown by immunostaining for neurofilaments. However, the capsule that had formed in contact with the chip was significantly thinner on the porous side than on the smooth side. Cellular protrusions had formed on the pSi side and the regenerated nerve tissue was found to attach firmly to this surface, while the tissue was hardly attached to the smooth silicon surface. We conclude that a pSi surface, due to its large surface area, diminished inflammatory response and firm adhesion to the tissue, should be a good material for the development of new implantable electronic nerve devices.

  15. Strengthening of polymer ordered porous materials based on a layered nanocomposite internal structure

    NASA Astrophysics Data System (ADS)

    Heng, Liping; Guo, Xieyou; Guo, Tianqi; Wang, Bin; Jiang, Lei

    2016-07-01

    Ordered porous polymeric films attract more and more attention because they have many advantages and broad application prospects in many fields. But because of their large flexibility and poor mechanical properties, some of the scope for application is greatly limited. Inspired by the ordered pore structure of the honeycomb and the layered structure of natural nacre, we prepared an ordered porous polymer film with a layered structure in the pore wall by the solvent-evaporation-restriction assisted hard template method. Compared with other samples, this kind of film with the layered structure showed both excellent mechanical properties and good stability. This kind of film with high mechanical strength, is considered to have wide applications in the areas of separation, biomedicine, precision instruments, aerospace, environmental protection and so on.Ordered porous polymeric films attract more and more attention because they have many advantages and broad application prospects in many fields. But because of their large flexibility and poor mechanical properties, some of the scope for application is greatly limited. Inspired by the ordered pore structure of the honeycomb and the layered structure of natural nacre, we prepared an ordered porous polymer film with a layered structure in the pore wall by the solvent-evaporation-restriction assisted hard template method. Compared with other samples, this kind of film with the layered structure showed both excellent mechanical properties and good stability. This kind of film with high mechanical strength, is considered to have wide applications in the areas of separation, biomedicine, precision instruments, aerospace, environmental protection and so on. Electronic supplementary information (ESI) available: SEM image of hexagonal silicon pillar templates, AFM images of clay platelets on a silicon substrate, photographs of free-standing gels, X-ray diffraction profiles for dried materials, FTIR and TGA of the samples, and

  16. Hierarchical simulator of biofilm growth and dynamics in granular porous materials

    NASA Astrophysics Data System (ADS)

    Kapellos, George E.; Alexiou, Terpsichori S.; Payatakes, Alkiviades C.

    2007-06-01

    A new simulator is developed for the prediction of the rate and pattern of growth of biofilms in granular porous media. The biofilm is considered as a heterogeneous porous material that exhibits a hierarchy of length scales. An effective-medium model is used to calculate the local hydraulic permeability and diffusion coefficient in the biofilm, as functions of the local geometric and physicochemical properties. The Navier-Stokes equations and the Brinkman equation are solved numerically to determine the velocity and pressure fields within the pore space and the biofilm, respectively. Biofilm fragments become detached if they are exposed to shear stress higher than a critical value. The detached fragments re-enter into the fluid stream and move within the pore space until they exit from the system or become reattached to downstream grain or biofilm surfaces. A Lagrangian-type simulation is used to determine the trajectories of detached fragments. The spatiotemporal distributions of a carbon source, an electron acceptor and a cell-to-cell signaling molecule are determined from the numerical solution of the governing convection-diffusion-reaction equations. The simulator incorporates growth and apoptosis kinetics for the bacterial cells and production and lysis kinetics for the EPS. The specific growth rate of active bacterial cells depends on the local concentrations of nutrients, mechanical stresses, and a quorum sensing mechanism. Growth-induced deformation of the biofilms is implemented with a cellular automaton approach. In this work, the spatiotemporal evolution of biofilms in the pore space of a 2D granular medium is simulated under high flow rate and nutrient-rich conditions. Transient changes in the pore geometry caused by biofilm growth lead to the formation of preferential flowpaths within the granular porous medium. The decrease of permeability caused by clogging of the porous medium is calculated and is found to be in qualitative agreement with published

  17. Porous graphitic carbon nanosheets derived from cornstalk biomass for advanced supercapacitors.

    PubMed

    Wang, Lei; Mu, Guang; Tian, Chungui; Sun, Li; Zhou, Wei; Yu, Peng; Yin, Jie; Fu, Honggang

    2013-05-01

    Porous graphitic carbon nanosheets (PGCS) are synthesized by an in situ self-generating template strategy based on the carburized effect of iron with cornstalks. Cornstalks firstly coordinate with [Fe(CN)(6)](4-) ions to form the cornstalk-[Fe(CN)(6)](4-) precursor. After carbonization and removal of the catalyst, PGCS are obtained. Series experiments indicate that PGCS can only be formed when using an iron-based catalyst that can generate a carburized phase during the pyrolytic process. The unique structures of PGCS exhibit excellent capacitive performance. The PGCS-1-1100 sample (synthesized from 0.1 M [Fe(CN)(6)](4-) with a carbonization temperature of 1100 °C), which shows excellent electrochemical capacitance (up to 213 F g(-1) at 1 A g(-1)), cycling stability, and rate performance in 6 M KOH electrolyte. In the two-electrode symmetric supercapacitors, the maximum energy densities that can be achieved are as high as 9.4 and 61.3 Wh kg(-1) in aqueous and organic electrolytes, respectively. Moreover, high energy densities of 8.3 and 40.6 Wh kg(-1) are achieved at the high power density of 10.5 kW kg(-1) in aqueous and organic electrolytes, respectively. This strategy holds great promise for preparing PGCS from natural resources, including cornstalks, as advanced electrodes in supercapacitors. PMID:23606450

  18. Investigation on thermo-mechanical instability of porous low dielectric constant materials

    NASA Astrophysics Data System (ADS)

    Zin, Emil Hyunbae

    This study investigates the structural stability of porous low dielectric constant materials (PLK) under thermal and mechanical load and the influence of contributing factors including porosity as intrinsic factor and plasma damage and moisture absorption as extrinsic factors on thermo-mechanical instability of PLK in advanced Cu/PLK interconnects. For this purpose, a ball indentation creep test technique was developed to examine the thermal and mechanical instability of PLK at relevant load and temperature conditions in the interconnect structure. Our exploration with the ball indentation creep test found that PLK films plastically deforms with time, indicating that viscoplastic deformation does occur under relevant conditions of PLK processing. On the basis of the results that the increase of the indentation depth with time shows more noticeable difference in PLK films with higher porosity, plasma exposure, and moisture absorption, it is our belief that PLK stability is greatly affected by porosity, plasma damage and moisture. Viscous flow was found to be mechanism for the viscoplastic deformation at the temperature and load of real PLK integration processing. This finding was obtained from the facts that the kinetics of the indentation creep fit very well with the viscous flow model and the extracted stress exponent is close to unity. Based on the results of temperature dependence in all PLK films, the activation energy(~1.5eV) of the viscosity back calculated from the experimental value of the kinetics was found to be much small than that of a pure glass (> 4eV). This suggests that the viscous flow of PLK is controlled by chemical reaction happening in PLK matrix. The FT-IR measurement for the examination of chemical bond reconfiguration shows that the intensity of Si-OH bonds increases with the flow while that of Si-O-Si, -CHX and Si-CH 3 bonds decreases, indicating that chemical reactions are involved in the deformation process. From these findings, it is

  19. Advanced materials and concepts for energy storage devices

    NASA Astrophysics Data System (ADS)

    Teng, Shiang Jen

    Over the last decade, technological progress and advances in the miniaturization of electronic devices have increased demands for light-weight, high-efficiency, and carbon-free energy storage devices. These energy storage devices are expected to play important roles in automobiles, the military, power plants, and consumer electronics. Two main types of electrical energy storage systems studied in this research are Li ion batteries and supercapacitors. Several promising solid state electrolytes and supercapacitor electrode materials are investigated in this research. The first section of this dissertation is focused on the novel results on pulsed laser annealing of Li7La3Zr2O12 (LLZO). LLZO powders with a tetragonal structure were prepared by a sol-gel technique, then a pulsed laser annealing process was employed to convert the tetragonal powders to cubic LLZO without any loss of lithium. The second section of the dissertation reports on how Li5La 3Nb2O12 (LLNO) was successfully synthesized via a novel molten salt synthesis (MSS) method at the relatively low temperature of 900°C. The low sintering temperature prevented the loss of lithium that commonly occurs during synthesis using conventional solid state or wet chemical reactions. The second type of energy storage device studied is supercapacitors. Currently, research on supercapacitors is focused on increasing their energy densities and lowering their overall production costs by finding suitable electrode materials. The third section of this dissertation details how carbonized woods electrodes were used as supercapacitor electrode materials. A high energy density of 45.6 Wh/kg and a high power density of 2000 W/kg were obtained from the supercapacitor made from carbonized wood electrodes. The high performance of the supercapacitor was discovered to originate from the hierarchical porous structures of the carbonized wood. Finally, the fourth section of this dissertation is on the electrochemical effects of

  20. Advanced insider threat mitigation workshop instructional materials

    SciTech Connect

    Gibbs, Philip; Larsen, Robert; O Brien, Mike; Edmunds, Tom

    2008-11-01

    Insiders represent a formidable threat to nuclear facilities. This set of workshop materials covers methodologies to analyze and approaches to mitigate the threat of an insider attempting abrupt and protracted theft of nuclear materials. This particular set of materials is a n update of a January 2008 version to add increased emphasis on Material Control and Accounting and its role with respect to protracted insider nuclear material theft scenarios.

  1. The use of acoustic methods to determine the parameters of porous materials

    NASA Astrophysics Data System (ADS)

    Malecki, Ignacy; Ranachowski, Jerzy

    Porous media are a subject of research in a variety of scientific disciplines, including physics, mechanics, electrical engineering, materials science, and acoustics. The subject of this article is a comparison of the methods used in theoretical mechanics with standard acoustic methods. The authors start by examining the method of static averaging of the mechanical properties of porous media. This method makes it possible to determine substitute static moduli of elasticity, which, however, does not meet the needs of acoustics. More suitable methods include the dynamic methods developed in the works of J. Lewandowski, among others. These methods are based on a motion equation in which the tensor of elasticity is assigned a complex value which accounts for the medium's dynamic properties and losses. The transition from a complex tensor of elasticity to the velocity and damping of an acoustic wave poses no particular problems. On the backdrop of the theory of porous materials used in mechanics, the authors present their own theory for the acoustic properties of these materials. They call it the theory of 'compound obstacles', which initially examines the interference offered by a solitary inclusion in a homogeneous medium to the propagation of an acoustic wave. This is followed by the calculation of the interference caused by a group of inclusions using the concept of the density of obstacles. In turn, this leads to general formulas for acoustic wave velocity and damping as functions of obstacle density. The authors consider examples of a spherical inclusion in a liquid and a hollow spheroidal inclusion in a solid. The article also contains the results of experiments conducted to verify the 'compound obstacles' theory. The authors measured the velocity of an ultrasound wave in electrical engineering porcelain with varying degrees of porosity and in glycerine in which glass balls were suspended.

  2. Fabrication of Ruthenium Nanoparticles in Porous Organic Polymers: Towards Advanced Heterogeneous Catalytic Nanoreactors.

    PubMed

    Mondal, John; Kundu, Sudipta K; Hung Ng, Wilson Kwok; Singuru, Ramana; Borah, Parijat; Hirao, Hajime; Zhao, Yanli; Bhaumik, Asim

    2015-12-21

    A novel strategy has been adopted for the construction of a copolymer of benzene-benzylamine-1 (BBA-1), which is a porous organic polymer (POP) with a high BET surface area, through Friedel-Crafts alkylation of benzylamine and benzene by using formaldehyde dimethyl acetal as a cross-linker and anhydrous FeCl3 as a promoter. Ruthenium nanoparticles (Ru NPs) were successfully distributed in the interior cavities of polymers through NaBH4, ethylene glycol, and hydrothermal reduction routes, which delivered Ru-A, Ru-B, and Ru-C materials, respectively, and avoided aggregation of metal NPs. Homogeneous dispersion, the nanoconfinement effect of the polymer, and the oxidation state of Ru NPs were verified by employing TEM, energy-dispersive X-ray spectroscopy mapping, cross polarization magic-angle spinning (13)C NMR spectroscopy, and X-ray photoelectron spectroscopy analytical tools. These three new Ru-based POP materials exhibited excellent catalytic performance in the hydrogenation of nitroarenes at RT (with a reaction time of only ≈ 30 min), with high conversion, selectivity, stability, and recyclability for several catalytic cycles, compared with other traditional materials, such as Ru@C, Ru@SiO2, and Ru@TiO2, but no clear agglomeration or loss of catalytic activity was observed. The high catalytic performance of the ruthenium-based POP materials is due to the synergetic effect of nanoconfinement and electron donation offered by the 3D POP network. DFT calculations showed that hydrogenation of nitrobenzene over the Ru (0001) catalyst surface through a direct reaction pathway is more favorable than that through an indirect reaction pathway.

  3. Fabrication of Ruthenium Nanoparticles in Porous Organic Polymers: Towards Advanced Heterogeneous Catalytic Nanoreactors.

    PubMed

    Mondal, John; Kundu, Sudipta K; Hung Ng, Wilson Kwok; Singuru, Ramana; Borah, Parijat; Hirao, Hajime; Zhao, Yanli; Bhaumik, Asim

    2015-12-21

    A novel strategy has been adopted for the construction of a copolymer of benzene-benzylamine-1 (BBA-1), which is a porous organic polymer (POP) with a high BET surface area, through Friedel-Crafts alkylation of benzylamine and benzene by using formaldehyde dimethyl acetal as a cross-linker and anhydrous FeCl3 as a promoter. Ruthenium nanoparticles (Ru NPs) were successfully distributed in the interior cavities of polymers through NaBH4, ethylene glycol, and hydrothermal reduction routes, which delivered Ru-A, Ru-B, and Ru-C materials, respectively, and avoided aggregation of metal NPs. Homogeneous dispersion, the nanoconfinement effect of the polymer, and the oxidation state of Ru NPs were verified by employing TEM, energy-dispersive X-ray spectroscopy mapping, cross polarization magic-angle spinning (13)C NMR spectroscopy, and X-ray photoelectron spectroscopy analytical tools. These three new Ru-based POP materials exhibited excellent catalytic performance in the hydrogenation of nitroarenes at RT (with a reaction time of only ≈ 30 min), with high conversion, selectivity, stability, and recyclability for several catalytic cycles, compared with other traditional materials, such as Ru@C, Ru@SiO2, and Ru@TiO2, but no clear agglomeration or loss of catalytic activity was observed. The high catalytic performance of the ruthenium-based POP materials is due to the synergetic effect of nanoconfinement and electron donation offered by the 3D POP network. DFT calculations showed that hydrogenation of nitrobenzene over the Ru (0001) catalyst surface through a direct reaction pathway is more favorable than that through an indirect reaction pathway. PMID:26572500

  4. Highly porous thermal protection materials: Modelling and prediction of the methodical experimental errors

    NASA Astrophysics Data System (ADS)

    Cherepanov, Valery V.; Alifanov, Oleg M.; Morzhukhina, Alena V.; Budnik, Sergey A.

    2016-11-01

    The formation mechanisms and the main factors affecting the systematic error of thermocouples were investigated. According to the results of experimental studies and mathematical modelling it was established that in highly porous heat resistant materials for aerospace application the thermocouple errors are determined by two competing mechanisms provided correlation between the errors and the difference between radiation and conduction heat fluxes. The comparative analysis was carried out and some features of the methodical error formation related to the distances from the heated surface were established.

  5. Constitutive model for geological and other porous materials under dynamic loading

    SciTech Connect

    Dey, T.N.

    1991-01-01

    An effective stress model is described for use in numerical calculations on porous materials which are partially or fully saturated with water. The flow rule chosen for the shear failure portion of the model is examined and shown to have significant influence on wave propagation results. A flow rule which produces dilatancy results in less attenuation than a rule producing shear-enhanced void collapse. The dilatancy producing rule is less prone to producing liquefaction and results in significantly higher stress levels behind the wave front. 8 refs., 6 figs.

  6. Cost-effective synthesis of amine-tethered porous materials for carbon capture.

    PubMed

    Lu, Weigang; Bosch, Mathieu; Yuan, Daqiang; Zhou, Hong-Cai

    2015-02-01

    A truly cost-effective strategy for the synthesis of amine-tethered porous polymer networks (PPNs) has been developed. A network containing diethylenetriamine (PPN-125-DETA) exhibits a high working capacity comparable to current state-of-art technology (30 % monoethanolamine solutions), yet it requires only one third as much energy for regeneration. It has also been demonstrated to retain over 90 % capacity after 50 adsorption-desorption cycles of CO2 in a temperature-swing adsorption process. The results suggest that PPN-125-DETA is a very promising new material for carbon capture from flue gas streams.

  7. Transfer matrix modeling and experimental validation of cellular porous material with resonant inclusions.

    PubMed

    Doutres, Olivier; Atalla, Noureddine; Osman, Haisam

    2015-06-01

    Porous materials are widely used for improving sound absorption and sound transmission loss of vibrating structures. However, their efficiency is limited to medium and high frequencies of sound. A solution for improving their low frequency behavior while keeping an acceptable thickness is to embed resonant structures such as Helmholtz resonators (HRs). This work investigates the absorption and transmission acoustic performances of a cellular porous material with a two-dimensional periodic arrangement of HR inclusions. A low frequency model of a resonant periodic unit cell based on the parallel transfer matrix method is presented. The model is validated by comparison with impedance tube measurements and simulations based on both the finite element method and a homogenization based model. At the HR resonance frequency (i) the transmission loss is greatly improved and (ii) the sound absorption of the foam can be either decreased or improved depending on the HR tuning frequency and on the thickness and properties of the host foam. Finally, the diffuse field sound absorption and diffuse field sound transmission loss performance of a 2.6 m(2) resonant cellular material are measured. It is shown that the improvements observed at the Helmholtz resonant frequency on a single cell are confirmed at a larger scale. PMID:26093437

  8. High-throughput Characterization of Porous Materials Using Graphics Processing Units

    SciTech Connect

    Kim, Jihan; Martin, Richard L.; Ruebel, Oliver; Haranczyk, Maciej; Smit, Berend

    2012-03-19

    We have developed a high-throughput graphics processing units (GPU) code that can characterize a large database of crystalline porous materials. In our algorithm, the GPU is utilized to accelerate energy grid calculations where the grid values represent interactions (i.e., Lennard-Jones + Coulomb potentials) between gas molecules (i.e., CH$_{4}$ and CO$_{2}$) and material's framework atoms. Using a parallel flood fill CPU algorithm, inaccessible regions inside the framework structures are identified and blocked based on their energy profiles. Finally, we compute the Henry coefficients and heats of adsorption through statistical Widom insertion Monte Carlo moves in the domain restricted to the accessible space. The code offers significant speedup over a single core CPU code and allows us to characterize a set of porous materials at least an order of magnitude larger than ones considered in earlier studies. For structures selected from such a prescreening algorithm, full adsorption isotherms can be calculated by conducting multiple grand canonical Monte Carlo simulations concurrently within the GPU.

  9. High-Throughput Characterization of Porous Materials Using Graphics Processing Units.

    PubMed

    Kim, Jihan; Martin, Richard L; Rübel, Oliver; Haranczyk, Maciej; Smit, Berend

    2012-05-01

    We have developed a high-throughput graphics processing unit (GPU) code that can characterize a large database of crystalline porous materials. In our algorithm, the GPU is utilized to accelerate energy grid calculations, where the grid values represent interactions (i.e., Lennard-Jones + Coulomb potentials) between gas molecules (i.e., CH4 and CO2) and materials' framework atoms. Using a parallel flood fill central processing unit (CPU) algorithm, inaccessible regions inside the framework structures are identified and blocked, based on their energy profiles. Finally, we compute the Henry coefficients and heats of adsorption through statistical Widom insertion Monte Carlo moves in the domain restricted to the accessible space. The code offers significant speedup over a single core CPU code and allows us to characterize a set of porous materials at least an order of magnitude larger than those considered in earlier studies. For structures selected from such a prescreening algorithm, full adsorption isotherms can be calculated by conducting multiple Grand Canonical Monte Carlo (GCMC) simulations concurrently within the GPU.

  10. On wave propagation characteristics in fluid saturated porous materials by a nonlocal Biot theory

    NASA Astrophysics Data System (ADS)

    Tong, Lihong; Yu, Yang; Hu, Wentao; Shi, Yufeng; Xu, Changjie

    2016-09-01

    A nonlocal Biot theory is developed by combing Biot theory and nonlocal elasticity theory for fluid saturated porous material. The nonlocal parameter is introduced as an independent variable for describing wave propagation characteristics in poroelastic material. A physical insight on nonlocal term demonstrates that the nonlocal term is a superposition of two effects, one is inertia force effect generated by fluctuation of porosity and the other is pore size effect inherited from nonlocal constitutive relation. Models for situations of excluding fluid nonlocal effect and including fluid nonlocal effect are proposed. Comparison with experiment confirms that model without fluid nonlocal effect is more reasonable for predicting wave characteristics in saturated porous materials. The negative dispersion is observed theoretically which agrees well with the published experimental data. Both wave velocities and quality factors as functions of frequency and nonlocal parameter are examined in practical cases. A few new physical phenomena such as backward propagation and disappearance of slow wave when exceeding critical frequency and disappearing shear wave in high frequency range, which were not predicted by Biot theory, are demonstrated.

  11. Transfer matrix modeling and experimental validation of cellular porous material with resonant inclusions.

    PubMed

    Doutres, Olivier; Atalla, Noureddine; Osman, Haisam

    2015-06-01

    Porous materials are widely used for improving sound absorption and sound transmission loss of vibrating structures. However, their efficiency is limited to medium and high frequencies of sound. A solution for improving their low frequency behavior while keeping an acceptable thickness is to embed resonant structures such as Helmholtz resonators (HRs). This work investigates the absorption and transmission acoustic performances of a cellular porous material with a two-dimensional periodic arrangement of HR inclusions. A low frequency model of a resonant periodic unit cell based on the parallel transfer matrix method is presented. The model is validated by comparison with impedance tube measurements and simulations based on both the finite element method and a homogenization based model. At the HR resonance frequency (i) the transmission loss is greatly improved and (ii) the sound absorption of the foam can be either decreased or improved depending on the HR tuning frequency and on the thickness and properties of the host foam. Finally, the diffuse field sound absorption and diffuse field sound transmission loss performance of a 2.6 m(2) resonant cellular material are measured. It is shown that the improvements observed at the Helmholtz resonant frequency on a single cell are confirmed at a larger scale.

  12. Analysis of an advanced technology subsonic turbofan incorporating revolutionary materials

    NASA Technical Reports Server (NTRS)

    Knip, Gerald, Jr.

    1987-01-01

    Successful implementation of revolutionary composite materials in an advanced turbofan offers the possibility of further improvements in engine performance and thrust-to-weight ratio relative to current metallic materials. The present analysis determines the approximate engine cycle and configuration for an early 21st century subsonic turbofan incorporating all composite materials. The advanced engine is evaluated relative to a current technology baseline engine in terms of its potential fuel savings for an intercontinental quadjet having a design range of 5500 nmi and a payload of 500 passengers. The resultant near optimum, uncooled, two-spool, advanced engine has an overall pressure ratio of 87, a bypass ratio of 18, a geared fan, and a turbine rotor inlet temperature of 3085 R. Improvements result in a 33-percent fuel saving for the specified misssion. Various advanced composite materials are used throughout the engine. For example, advanced polymer composite materials are used for the fan and the low pressure compressor (LPC).

  13. Fundamental Characterization Studies of Advanced Photocatalytic Materials

    NASA Astrophysics Data System (ADS)

    Phivilay, Somphonh Peter

    Solar powered photocatalytic water splitting has been proposed as a method for the production of sustainable, non-carbon hydrogen fuel. Although much technological progress has been achieved in recent years in the discovery of advanced photocatalytic materials, the progress in the fundamental scientific understanding of such novel, complex mixed oxide and oxynitride photocatalysts has significantly lagged. One of the major reasons for this slow scientific progress is the limited number of reported surface characterization studies of the complex bulk mixed oxide and oxynitride photocatalyst systems. Although photocatalytic splitting of water by bulk mixed oxide and oxynitride materials involves both bulk (generation of excited electrons and holes) and surface phenomena (reaction of H2O with excited electrons and holes at the surface), the photocatalysis community has almost completely ignored the surface characteristics of such complex bulk photocatalysts and correlates the photocatalytic properties with bulk properties. Some of the most promising photocatalyst systems (NaTaO3, GaN, (Ga1-xZnx)(N1-xOx) and TaON) were investigated to establish fundamental bulk/surface structure photoactivity relationships. The bulk molecular and electronic structures of the photocatalysts were determined with Raman and UV-vis spectroscopy. Photoluminescence (PL) and transient PL spectroscopy were provided insight into how recombination of photogenerated electrons is related to the photocatalysis activity. The chemical states and atomic compositions of the surface region of the photocatalysts were determined with high resolution X-ray photoelectron spectroscopy (˜1-3 nm) and high sensitivity-low energy ion scattering spectroscopy (˜0.3 nm). The new insights obtained from surface characterization clarified the role of La and Ni promoters species for the NaTaO3 photocatalyst system. The La2O3 additive was found to be a structural promoter that stabilizes small NaTaO3 nanoparticles (NPs

  14. Synthesis of nitrogen-doped porous carbon nanofibers as an efficient electrode material for supercapacitors.

    PubMed

    Chen, Li-Feng; Zhang, Xu-Dong; Liang, Hai-Wei; Kong, Mingguang; Guan, Qing-Fang; Chen, Ping; Wu, Zhen-Yu; Yu, Shu-Hong

    2012-08-28

    Supercapacitors (also known as ultracapacitors) are considered to be the most promising approach to meet the pressing requirements of energy storage. Supercapacitive electrode materials, which are closely related to the high-efficiency storage of energy, have provoked more interest. Herein, we present a high-capacity supercapacitor material based on the nitrogen-doped porous carbon nanofibers synthesized by carbonization of macroscopic-scale carbonaceous nanofibers (CNFs) coated with polypyrrole (CNFs@polypyrrole) at an appropriate temperature. The composite nanofibers exhibit a reversible specific capacitance of 202.0 F g(-1) at the current density of 1.0 A g(-1) in 6.0 mol L(-1) aqueous KOH electrolyte, meanwhile maintaining a high-class capacitance retention capability and a maximum power density of 89.57 kW kg(-1). This kind of nitrogen-doped carbon nanofiber represents an alternative promising candidate for an efficient electrode material for supercapacitors.

  15. New Advances in SuperConducting Materials

    ScienceCinema

    None

    2016-07-12

    Superconducting materials will transform the world's electrical infrastructure, saving billions of dollars once the technical details and installation are in place. At Los Alamos National Laboratory, new materials science concepts are bringing this essential technology closer to widespread industrial use.

  16. Development of advanced thermoelectric materials, phase A

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Work performed on the chemical system characterized by chrome sulfide, chrome selenide, lanthanum selenide, and lanthanum sulfide is described. Most materials within the chemical systems possess the requisites for attractive thermoelectric materials. The preparation of the alloys is discussed. Graphs show the Seebeck coefficient, electrical resistivity, and thermal conductivity of various materials within the chemical systems. The results of selected doping are included.

  17. Methods of using structures including catalytic materials disposed within porous zeolite materials to synthesize hydrocarbons

    SciTech Connect

    Rollins, Harry W.; Petkovic, Lucia M.; Ginosar, Daniel M.

    2011-02-01

    Catalytic structures include a catalytic material disposed within a zeolite material. The catalytic material may be capable of catalyzing a formation of methanol from carbon monoxide and/or carbon dioxide, and the zeolite material may be capable of catalyzing a formation of hydrocarbon molecules from methanol. The catalytic material may include copper and zinc oxide. The zeolite material may include a first plurality of pores substantially defined by a crystal structure of the zeolite material and a second plurality of pores dispersed throughout the zeolite material. Systems for synthesizing hydrocarbon molecules also include catalytic structures. Methods for synthesizing hydrocarbon molecules include contacting hydrogen and at least one of carbon monoxide and carbon dioxide with such catalytic structures. Catalytic structures are fabricated by forming a zeolite material at least partially around a template structure, removing the template structure, and introducing a catalytic material into the zeolite material.

  18. Optimization and Use of 3D sintered porous material in medical field for mixing fibrin glue.

    NASA Astrophysics Data System (ADS)

    Delmotte, Y.; Laroumanie, H.; Brossard, G.

    2012-04-01

    In medical field, Mixing of two or more chemical components (liquids and/or gases) is extremely important as improper mixing can affect the physico-chemical properties of the final product. At Baxter Healthcare Corporation, we are using a sintered porous material (PM) as a micro-mixer in medical device for mixing Fibrinogen and Thrombin in order to obtain a homogeneous polymerized Fibrin glue clot used in surgery. First trials were carried out with an interconnected PM from Porvair® (made of PE - porosity: 40% - permeability: 18Darcy). The injection rate is very low, usually about 10mL/min (Re number about 50) which keeps fluids in a laminar flow. Such a low flow rate does not favour mixing of fluids having gradient of viscosity if a mixer is not used. Promising results that were obtained lead the team to understand this ability to mix fluids which will be presented in the poster. Topology of porous media (PM) which associates a solid phase with interconnected (or not) porous structure is known and used in many commodity products. Researches on PM usually focus on flows inside this structure. By opposition to transport and filtration capacity, as well as mechanic and thermic properties, mixing is rarely associated with PM. However over the past few years, we shown that some type of PM have a real capacity to mix certain fluids. Poster will also describe the problematic of mixing complex biological fluids as fibrinogen and Thrombin. They indeed present a large viscosity difference (ratio about 120) limiting the diffusion and the interaction between the two solutions. As those products are expensive, we used Water (1cPo) and Glycerol 87% (120cPo) which are matching the viscosities of Thrombin and Fibrinogen. A parametric investigation of the "porous micro-mixer" as well as a scale up investigation was carried out to examine the influence of both diffusion and advection to successful mix fluids of different viscosity. Experiments were implemented with Planar Laser

  19. Advanced materials for solid oxide fuel cells

    SciTech Connect

    Armstrong, T.R.; Stevenson, J.

    1995-08-01

    The purpose of this research is to improve the properties of the current state-of-the-art materials used for solid oxide fuel cells (SOFCs). The objectives are to: (1) develop materials based on modifications of the state-of-the-art materials; (2) minimize or eliminate stability problems in the cathode, anode, and interconnect; (3) Electrochemically evaluate (in reproducible and controlled laboratory tests) the current state-of-the-art air electrode materials and cathode/electrolyte interfacial properties; (4) Develop accelerated electrochemical test methods to evaluate the performance of SOFCs under controlled and reproducible conditions; and (5) Develop and test materials for use in low-temperature SOFCs. The goal is to modify and improve the current state-of-the-art materials and minimize the total number of cations in each material to avoid negative effects on the materials properties. Materials to reduce potential deleterious interactions, (3) improve thermal, electrical, and electrochemical properties, (4) develop methods to synthesize both state-of-the-art and alternative materials for the simultaneous fabricatoin and consolidation in air of the interconnections and electrodes with the solid electrolyte, and (5) understand electrochemical reactions at materials interfaces and the effects of component composition and processing on those reactions.

  20. Advanced Insider Threat Mitigation Workshop Instructional Materials

    SciTech Connect

    Gibbs, Philip; Larsen, Robert; O'Brien, Mike; Edmunds, Tom

    2009-02-01

    Insiders represent a formidable threat to nuclear facilities. This set of workshop materials covers methodologies to analyze and approaches to mitigate the threat of an insider attempting abrupt and protracted theft of nuclear materials. This particular set of materials is an update of a January 2008 version to add increased emphasis on Material Control and Accounting and its role with respect to protracted insider nuclear material theft scenarios. This report is a compilation of workshop materials consisting of lectures on technical and administrative measures used in Physical Protection (PP) and Material Control and Accounting (MC&A) and methods for analyzing their effectiveness against a postulated insider threat. The postulated threat includes both abrupt and protracted theft scenarios. Presentation is envisioned to be through classroom instruction and discussion. Several practical and group exercises are included for demonstration and application of the analysis approach contained in the lecture/discussion sessions as applied to a hypothetical nuclear facility.

  1. Materials Challenges for Advanced Combustion and Gasification Fossil Energy Systems

    NASA Astrophysics Data System (ADS)

    Sridhar, S.; Rozzelle, P.; Morreale, B.; Alman, D.

    2011-04-01

    This special section of Metallurgical and Materials Transactions is devoted to materials challenges associated with coal based energy conversion systems. The purpose of this introductory article is to provide a brief outline to the challenges associated with advanced combustion and advanced gasification, which has the potential of providing clean, affordable electricity by improving process efficiency and implementing carbon capture and sequestration. Affordable materials that can meet the demanding performance requirements will be a key enabling technology for these systems.

  2. Experimental investigation of the flow, oxidation, cooling, and thermal-fatigue characteristics of a laminated porous sheet material

    NASA Technical Reports Server (NTRS)

    Hickel, R. O.; Warren, E. L.; Kaufman, A.

    1972-01-01

    The basic flow and oxidation characteristics of a laminated porous material (Lamilloy) are presented. The oxidation characteristics of Lamilloy are compared to a wireform-type porous material for the case when both materials are made from Hastelloy-X alloy. The cooling performance of an air cooled vane made from Lamilloy, as determined from cascade tests made at gas temperatures ranging from 1388 to 1741 C (2350 to 3165 F) is also discussed, as well as of a cascade-type thermal fatigue test of the Lamilloy vane.

  3. Synthesis, structure and properties of hierarchical nanostructured porous materials studied by molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Chae, Kisung

    For applications of porous materials in many fields of technological importance, such as catalysis, filtration, separation, energy storage and conversion, the efficiency is often limited by chemical kinetics, and/or diffusion of reactants and products to and from the active sites. Hierarchical nanostructured porous materials (HNPMs) that possess both mesopores (2 nm < pore size < 50 nm) and micropores (pore size < 2 nm) have shown great potential for these applications as their bimodal porous structure can provide highly efficient mass transport through mesopores and high electrochemically accessible surface area from micropores. Despite extensive experimental studies, it remains a great challenge to quantify the synthesis-structure-properties relations in HNPMs due to the limitations of existing characterization tools and the difficulty in separating the sum of many effects in experiments. In this thesis work, we carried out a detailed study on the synthesis-structure-property relations in hierarchical nanostructured porous carbons (HNPCs) by using classical molecular dynamics (MD) simulations. We first developed a unique computational nanocasting approach in MD to mimic the synthesis of HNPCs with both mesopores from the templating and micropores from the direct quench of carbon source in MD. Mesoporous structure such as the pore size and the pore wall roughness as well as the microporous structure such as the density and the graphitic pore walls can be independently controlled by synthesis parameters, such as the size of the template, the interaction strength between the template and carbon source, the initial carbon density and the quench rate, respectively. These atomic models allowed us to quantify the structure-mechanical properties relation in aligned carbon nanotubes/amorphous porous carbon nanocomposites. Our study shows that there is an optimum balance between the crystallinity of CNTs and the number bridging bonds between CNTs and the microporous matrix

  4. Porous materials with pre-designed single-molecule traps for CO2 selective adsorption

    SciTech Connect

    Li, JR; Yu, JM; Lu, WG; Sun, LB; Sculley, J; Balbuena, PB; Zhou, HC

    2013-02-26

    Despite tremendous efforts, precise control in the synthesis of porous materials with pre-designed pore properties for desired applications remains challenging. Newly emerged porous metal-organic materials, such as metal-organic polyhedra and metal-organic frameworks, are amenable to design and property tuning, enabling precise control of functionality by accurate design of structures at the molecular level. Here we propose and validate, both experimentally and computationally, a precisely designed cavity, termed a 'single-molecule trap', with the desired size and properties suitable for trapping target CO2 molecules. Such a single-molecule trap can strengthen CO2-host interactions without evoking chemical bonding, thus showing potential for CO2 capture. Molecular single-molecule traps in the form of metal-organic polyhedra are designed, synthesised and tested for selective adsorption of CO2 over N-2 and CH4, demonstrating the trapping effect. Building these pre-designed single-molecule traps into extended frameworks yields metal-organic frameworks with efficient mass transfer, whereas the CO2 selective adsorption nature of single-molecule traps is preserved.

  5. An investigation of the influence of acoustic waves on the liquid flow through a porous material.

    PubMed

    Poesio, Pietro; Ooms, Gijs; Barake, Sander; van der Bas, Fred

    2002-05-01

    An experimental and theoretical investigation has been made of the influence of high-frequency acoustic waves on the flow of a liquid through a porous material. The experiments have been performed on Berea sandstone cores. Two acoustic horns were used with frequencies of 20 and 40 kHz, and with maximum power output of 2 and 0.7 kW, respectively. Also, a temperature measurement of the flowing liquid inside the core was made. A high external pressure was applied in order to avoid cavitation. The acoustic waves were found to produce a significant effect on the pressure gradient at constant liquid flow rate through the core samples. During the application of acoustic waves the pressure gradient inside the core decreases. This effect turned out to be due to the decrease of the liquid viscosity caused by an increase in liquid temperature as a result of the acoustic energy dissipation inside the porous material. Also, a theoretical model has been developed to calculate the dissipation effect on the viscosity and on the pressure gradient. The model predictions are in reasonable agreement with the experimental data.

  6. Limit analysis and conic programming: `porous Drucker Prager' material and Gurson's model

    NASA Astrophysics Data System (ADS)

    Trillat, Malorie; Pastor, Joseph; Thoré, Philippe

    2006-10-01

    Extending a previous work on the Gurson model for a 'porous von Mises' material, the present study first focuses on the yield criterion of a 'porous Drucker-Prager' material with spherical cavities. On the basis of the Gurson micro-macro model and a second order conic programming ( SOCP) formulation, calculated inner and outer approaches to the criterion are very close, providing a reliable estimate of the yield criterion. Comparison with an analytical criterion recently proposed by Barthélémy and Dormieux—from a nonlinear homogenization method—shows both excellent agreement when considering tensile average boundary conditions and substantial improvement under compressive conditions. Then the results of an analogous study in the case of cylindrical cavities in plane strain are presented. It is worth noting that obtaining these results was made possible by using MOSEK, a recent commercial SOCP code, whose impressive efficiency was already seen in our previous works. To cite this article: M. Trillat et al., C. R. Mecanique 334 (2006).

  7. Multi-contrast 3D X-ray imaging of porous and composite materials

    SciTech Connect

    Sarapata, Adrian; Herzen, Julia; Ruiz-Yaniz, Maite; Zanette, Irene; Rack, Alexander; Pfeiffer, Franz

    2015-04-13

    Grating-based X-ray computed tomography allows for simultaneous and nondestructive determination of the full X-ray complex index of refraction and the scattering coefficient distribution inside an object in three dimensions. Its multi-contrast capabilities combined with a high resolution of a few micrometers make it a suitable tool for assessing multiple phases inside porous and composite materials such as concrete. Here, we present quantitative results of a proof-of-principle experiment performed on a concrete sample. Thanks to the complementarity of the contrast channels, more concrete phases could be distinguished than in conventional attenuation-based imaging. The phase-contrast reconstruction shows high contrast between the hardened cement paste and the aggregates and thus allows easy 3D segmentation. Thanks to the dark-field image, micro-cracks inside the coarse aggregates are visible. We believe that these results are extremely interesting in the field of porous and composite materials studies because of unique information provided by grating interferometry in a non-destructive way.

  8. Porous graphitic carbon nanosheets as a high-rate anode material for lithium-ion batteries.

    PubMed

    Chen, Long; Wang, Zhiyuan; He, Chunnian; Zhao, Naiqin; Shi, Chunsheng; Liu, Enzuo; Li, Jiajun

    2013-10-01

    Two-dimensional (2D) porous graphitic carbon nanosheets (PGC nanosheets) as a high-rate anode material for lithium storage were synthesized by an easy, low-cost, green, and scalable strategy that involves the preparation of the PGC nanosheets with Fe and Fe3O4 nanoparticles embedded (indicated with (Fe&Fe3O4)@PGC nanosheets) using glucose as the carbon precursor, iron nitrate as the metal precursor, and a surface of sodium chloride as the template followed by the subsequent elimination of the Fe and Fe3O4 nanoparticles from the (Fe&Fe3O4)@PGC nanosheets by acid dissolution. The unique 2D integrative features and porous graphitic characteristic of the carbon nanosheets with high porosity, high electronic conductivity, and outstanding mechanical flexibility and stability are very favorable for the fast and steady transfer of electrons and ions. As a consequence, a very high reversible capacity of up to 722 mAh/g at a current density of 100 mA/g after 100 cycles, a high rate capability (535, 380, 200, and 115 mAh/g at 1, 10, 20, and 30 C, respectively, 1 C = 372 mA/g), and a superior cycling performance at an ultrahigh rate (112 mAh/g at 30 C after 570 charge-discharge cycles) are achieved by using these nanosheets as a lithium-ion-battery anode material.

  9. Supported Intrinsically Porous Oligomers as Hybrid Materials for Separations, Storage, and Sensing

    NASA Astrophysics Data System (ADS)

    Thompson, Anthony Boone

    Adsorption-desorption phenomena are often difficult to study at the molecular level because the surfaces on which they occur can be heterogeneous, giving a wide distribution of adsorption sites and associated energies. Considering that these phenomena underlie an incredibly wide variety of industrially important processes, a better understanding could aid in the development of more efficient methods. In this work, we describe an approach to designing materials with well-defined adsorption sites by covalently attaching intrinsically porous molecules to solid surfaces by a rigid multidentate linker. These cup-shaped molecules are intended to act as adsorption sites on the material, whereas the rigid attachment to the solid support serves to prevent movement and conformational changes of the sites, leading to better understanding of adsorption phenomena. As a proof-of-concept application, materials were used for adsorption of n-butanol biofuel and related compounds from dilute aqueous solution. The materials were thermally and hydrolytically stable, and adsorption phenomena were reversible. Adsorption sites containing more hydrophobic molecular area led to stronger adsorption, suggesting that it is driven by weak van der Waals forces. Likewise, adsorption sites that were strongly polarized performed poorly, possibly reflecting a greater energy penalty of removing water molecules from the cavity. Upon placing a Lewis acidic metal at the bottom of the cavity, an enhancement was seen only with the most acidic metal, which may indicate weak guest coordination. Observing that hydrophobic interactions dominate adsorption on these materials, efforts were made to develop hybrid materials with large hydrophobic area for adsorption. Glaser coupling of diethynylbenzene was used to grow oligo(phenylene butadiynylene)s from the surface of silica, resulting in materials that were more than 25% organic by weight. In addition to their potential use as adsorbents, these materials may

  10. Advanced materials for space nuclear power systems

    NASA Technical Reports Server (NTRS)

    Titran, Robert H.; Grobstein, Toni L.; Ellis, David L.

    1991-01-01

    The overall philosophy of the research was to develop and characterize new high temperature power conversion and radiator materials and to provide spacecraft designers with material selection options and design information. Research on three candidate materials (carbide strengthened niobium alloy PWC-11 for fuel cladding, graphite fiber reinforced copper matrix composites for heat rejection fins, and tungsten fiber reinforced niobium matrix composites for fuel containment and structural supports) considered for space power system applications is discussed. Each of these types of materials offers unique advantages for space power applications.

  11. New Advance in SuperConducting Materials

    SciTech Connect

    2009-03-02

    Superconducting materials will transform the world's electrical infrastructure, saving billions of dollars once the technical details and installation are in place. At Los Alamos National Laborator...  

  12. Advanced materials for space nuclear power systems

    NASA Technical Reports Server (NTRS)

    Titran, Robert H.; Grobstein, Toni L.; Ellis, David L.

    1991-01-01

    The overall philosophy of the research was to develop and characterize new high temperature power conversion and radiator materials and to provide spacecraft designers with material selection options and design information. Research on three candidate materials (carbide strengthened niobium alloy PWC-11 for fuel cladding, graphite fiber reinforced copper matrix composites for heat rejection fins, and tungsten fiber reinforced niobium matrix composites for fuel containment and structural supports considered for space power system applications is discussed. Each of these types of materials offers unique advantages for space power applications.

  13. Progress in advanced high temperature materials technology

    NASA Technical Reports Server (NTRS)

    Freche, J. C.; Ault, G. M.

    1976-01-01

    Significant progress has recently been made in many high temperature material categories pertinent to such applications by the industrial community. These include metal matrix composites, superalloys, directionally solidified eutectics, coatings, and ceramics. Each of these material categories is reviewed and the current state-of-the-art identified, including some assessment, when appropriate, of progress, problems, and future directions.

  14. Advanced materials for solid oxide fuel cells

    SciTech Connect

    Armstrong, T.R.; Stevenson, J.; Paulik, S.

    1996-12-31

    Purpose of the research is to improve the properties of current state- of-the-art materials used for SOFCs. The project includes interconnect development, high-performance cathode, electrochemical testing, and accelerated testing. This document reports results of mechanical tests (bend strength, elastic modulus, fracture strength) of acceptor-substituted lanthanum chromite (interconnect material).

  15. Breath Figures of Nanoscale Bricks: A Universal Method for Creating Hierarchic Porous Materials from Inorganic Nanoparticles Stabilized with Mussel-Inspired Copolymers.

    PubMed

    Saito, Yuta; Shimomura, Masatsugu; Yabu, Hiroshi

    2014-09-01

    High-performance catalysts and photovoltaics are required for building an environmentally sustainable society. Because catalytic and photovoltaic reactions occur at the interfaces between reactants and surfaces, the chemical, physical, and structural properties of interfaces have been the focus of much research. To improve the performance of these materials further, inorganic porous materials with hierarchic porous architectures have been fabricated. The breath figure technique allows preparing porous films by using water droplets as templates. In this study, a valuable preparation method for hierarchic porous inorganic materials is shown. Hierarchic porous materials are prepared from surface-coated inorganic nanoparticles with amphiphilic copolymers having catechol moieties followed by sintering. Micron-scale pores are prepared by using water droplets as templates, and nanoscale pores are formed between the nanoparticles. The fabrication method allows the preparation of hierarchic porous films from inorganic nanoparticles of various shapes and materials.

  16. Superstructured Carbon Nanotube/Porous Silicon Hybrid Materials for Lithium-Ion Battery Anodes

    NASA Astrophysics Data System (ADS)

    Lee, Jun-Ki; Kang, Shin-Hyun; Choi, Sung-Min

    2015-03-01

    High energy Li-ion batteries (LIBs) are in great demand for electronics, electric-vehicles, and grid-scale energy storage. To further increase the energy and power densities of LIBs, Si anodes have been intensively explored due to their high capacity, and high abundance compared with traditional carbon anodes. However, the poor cycle-life caused by large volume expansion during charge/discharge process has been an impediment to its applications. Recently, superstructured Si materials were received attentions to solve above mentioned problem in excellent mechanical properties, large surface area, and fast Li and electron transportation aspects, but applying superstructures to anode is in early stage yet. Here, we synthesized superstructured carbon nanotubes (CNTs)/porous Si hybrid materials and its particular electrochemical properties will be presented. Department of Nuclear and Quantum Engineering

  17. Short time proton dynamics in bulk ice and in porous anode solid oxide fuel cell materials

    SciTech Connect

    Basoli, Francesco; Senesi, Roberto; Kolesnikov, Alexander I; Licoccia, Silvia

    2014-01-01

    Oxygen reduction and incorporation into solid electrolytes and the reverse reaction of oxygen evolution play a cru-cial role in Solid Oxide Fuel Cell (SOFC) applications. However a detailed un derstanding of the kinetics of the cor-responding reactions, i.e. on reaction mechanisms, rate limiting steps, reaction paths, electrocatalytic role of materials, is still missing. These include a thorough characterization of the binding potentials experienced by protons in the lattice. We report results of Inelastic Neutron Scattering (INS) measurements of the vibrational state of the protons in Ni- YSZ highly porous composites (75% to 90% ), a ceramic-metal material showing a high electrical conductivity and ther mal stability, which is known to be most effectively used as anodes for solid ox ide fuel cells. The results are compared with INS and Deep Inelastic Neutron Scattering (DINS) experiments on the proton binding states in bulk ice.

  18. Sound transmission through double cylindrical shells lined with porous material under turbulent boundary layer excitation

    NASA Astrophysics Data System (ADS)

    Zhou, Jie; Bhaskar, Atul; Zhang, Xin

    2015-11-01

    This paper investigates sound transmission through double-walled cylindrical shell lined with poroelastic material in the core, excited by pressure fluctuations due to the exterior turbulent boundary layer (TBL). Biot's model is used to describe the sound wave propagating in the porous material. Three types of constructions, bonded-bonded, bonded-unbonded and unbonded-unbonded, are considered in this study. The power spectral density (PSD) of the inner shell kinetic energy is predicted for two turbulent boundary layer models, different air gap depths and three types of polyimide foams, respectively. The peaks of the inner shell kinetic energy due to shell resonance, hydrodynamic coincidence and acoustic coincidence are discussed. The results show that if the frequency band over the ring frequency is of interest, an air gap, even if very thin, should exist between the two elastic shells for better sound insulation. And if small density foam has a high flow resistance, a superior sound insulation can still be maintained.

  19. Pumping through porous hydrophobic/oleophilic materials: an alternative technology for oil spill remediation.

    PubMed

    Ge, Jin; Ye, Yin-Dong; Yao, Hong-Bin; Zhu, Xi; Wang, Xu; Wu, Liang; Wang, Jin-Long; Ding, Hang; Yong, Ni; He, Ling-Hui; Yu, Shu-Hong

    2014-04-01

    Recently, porous hydrophobic/oleophilic materials (PHOMs) have been shown to be the most promising candidates for cleaning up oil spills; however, due to their limited absorption capacity, a large quantity of PHOMs would be consumed in oil spill remediation, causing serious economic problems. In addition, the complicated and time-consuming process of oil recovery from these sorbents is also an obstacle to their practical application. To solve the above problems, we apply external pumping on PHOMs to realize the continuous collection of oil spills in situ from the water surface with high speed and efficiency. Based on this novel design, oil/water separation and oil collection can be simultaneously achieved in the remediation of oil spills, and the oil sorption capacity is no longer limited to the volume and weight of the sorption material. This novel external pumping technique may bring PHOMs a step closer to practical application in oil spill remediation.

  20. Development of a Chitosan-Based Biofoam: Application to the Processing of a Porous Ceramic Material

    PubMed Central

    Mathias, Jean-Denis; Tessier-Doyen, Nicolas; Michaud, Philippe

    2011-01-01

    Developing biofoams constitutes a challenging issue for several applications. The present study focuses on the development of a chitosan-based biofoam. Solutions of chitosan in acetic acid were dried under vacuum to generate foams with high-order structures. Chitosan concentration influenced significantly the morphology of developed porosity and the organization of pores in the material. Physico-chemical characterizations were performed to investigate the effects of chitosan concentration on density and thermal conductivity of foams. Even if chitosan-based biofoams exhibit interesting insulating properties (typically around 0.06 W·m−1·K−1), it has been shown that their durabilities are limited when submitted to a wet media. So, a way of application consists to elaborate a ceramic material with open porosity from a slurry prepared with an organic solvent infiltrating the porous network of the foam. PMID:21541051

  1. Development of a chitosan-based biofoam: application to the processing of a porous ceramic material.

    PubMed

    Mathias, Jean-Denis; Tessier-Doyen, Nicolas; Michaud, Philippe

    2011-02-16

    Developing biofoams constitutes a challenging issue for several applications. The present study focuses on the development of a chitosan-based biofoam. Solutions of chitosan in acetic acid were dried under vacuum to generate foams with high-order structures. Chitosan concentration influenced significantly the morphology of developed porosity and the organization of pores in the material. Physico-chemical characterizations were performed to investigate the effects of chitosan concentration on density and thermal conductivity of foams. Even if chitosan-based biofoams exhibit interesting insulating properties (typically around 0.06 W·m(-1)·K(-1)), it has been shown that their durabilities are limited when submitted to a wet media. So, a way of application consists to elaborate a ceramic material with open porosity from a slurry prepared with an organic solvent infiltrating the porous network of the foam.

  2. Production of nanotubes in delignified porous cellulosic materials after hydrolysis with cellulase.

    PubMed

    Koutinas, Αthanasios Α; Papafotopoulou-Patrinou, Evgenia; Gialleli, Angelika-Ioanna; Petsi, Theano; Bekatorou, Argyro; Kanellaki, Maria

    2016-08-01

    In this study, tubular cellulose (TC), a porous cellulosic material produced by delignification of sawdust, was treated with a Trichoderma reesei cellulase in order to increase the proportion of nano-tubes. The effect of enzyme concentration and treatment duration on surface characteristics was studied and the samples were analyzed with BET, SEM and XRD. Also, a composite material of gelatinized starch and TC underwent enzymatic treatment in combination with amylase (320U) and cellulase (320U) enzymes. For TC, the optimum enzyme concentration (640U) led to significant increase of TC specific surface area and pore volume along with the reduction of pore diameter. It was also shown that the enzymatic treatment did not result to a significant change of cellulose crystallinity index. The produced nano-tubular cellulose shows potential for application to drug and chemical preservative delivery systems.

  3. Challenge to advanced materials processing with lasers in Japan

    NASA Astrophysics Data System (ADS)

    Miyamoto, Isamu

    2003-02-01

    Japan is one of the most advanced countries in manufacturing technology, and lasers have been playing an important role for advancement of manufacturing technology in a variety of industrial fields. Contribution of laser materials processing to Japanese industry is significant for both macroprocessing and microprocessing. The present paper describes recent trend and topics of industrial applications in terms of the hardware and the software to show how Japanese industry challenges to advanced materials processing using lasers, and national products related to laser materials processing are also briefly introduced.

  4. Advanced materials research for long-haul aircraft turbine engines

    NASA Technical Reports Server (NTRS)

    Signorelli, R. A.; Blankenship, C. P.

    1978-01-01

    The status of research efforts to apply low to intermediate temperature composite materials and advanced high temperature materials to engine components is reviewed. Emerging materials technologies and their potential benefits to aircraft gas turbines were emphasized. The problems were identified, and the general state of the technology for near term use was assessed.

  5. Advances in Processing of Bulk Ferroelectric Materials

    NASA Astrophysics Data System (ADS)

    Galassi, Carmen

    The development of ferroelectric bulk materials is still under extensive investigation, as new and challenging issues are growing in relation to their widespread applications. Progress in understanding the fundamental aspects requires adequate technological tools. This would enable controlling and tuning the material properties as well as fully exploiting them into the scale production. Apart from the growing number of new compositions, interest in the first ferroelectrics like BaTiO3 or PZT materials is far from dropping. The need to find new lead-free materials, with as high performance as PZT ceramics, is pushing towards a full exploitation of bariumbased compositions. However, lead-based materials remain the best performing at reasonably low production costs. Therefore, the main trends are towards nano-size effects and miniaturisation, multifunctional materials, integration, and enhancement of the processing ability in powder synthesis. Also, in control of dispersion and packing, to let densification occur in milder conditions. In this chapter, after a general review of the composition and main properties of the principal ferroelectric materials, methods of synthesis are analysed with emphasis on recent results from chemical routes and cold consolidation methods based on the colloidal processing.

  6. Lignin-Derived Advanced Carbon Materials.

    PubMed

    Chatterjee, Sabornie; Saito, Tomonori

    2015-12-01

    Lignin is a highly abundant source of renewable carbon that can be considered as a valuable sustainable source of biobased materials. By applying specific pretreatments and manufacturing methods, lignin can be converted into a variety of value-added carbon materials. However, the physical and chemical heterogeneities of lignin complicate its use as a feedstock. Herein lignin manufacturing process, the effects of pretreatments and manufacturing methods on the properties of product lignin, and structure-property relationships in various applications of lignin-derived carbon materials, such as carbon fibers, carbon mats, activated carbons, carbon films, and templated carbon, are discussed.

  7. Advances in nonlinear optical materials and devices

    NASA Technical Reports Server (NTRS)

    Byer, Robert L.

    1991-01-01

    The recent progress in the application of nonlinear techniques to extend the frequency of laser sources has come from the joint progress in laser sources and in nonlinear materials. A brief summary of the progress in diode pumped solid state lasers is followed by an overview of progress in nonlinear frequency extension by harmonic generation and parametric processes. Improved nonlinear materials including bulk crystals, quasiphasematched interactions, guided wave devices, and quantum well intersubband studies are discussed with the idea of identifying areas of future progress in nonlinear materials and devices.

  8. Lignin-Derived Advanced Carbon Materials

    SciTech Connect

    Chatterjee, Sabornie; Saito, Tomonori

    2015-11-16

    Lignin is a highly abundant source of renewable carbon that can be considered as a valuable sustainable source of biobased materials. By applying specific pretreatments and manufacturing methods, it has been found that lignin can be converted into a variety of value-added carbon materials. However, the physical and chemical heterogeneities of lignin complicate its use as a feedstock. Herein, we discuss the lignin manufacturing process, the effects of pretreatments and manufacturing methods on the properties of product lignin, and structure–property relationships in various applications of lignin-derived carbon materials, such as carbon fibers, carbon mats, activated carbons, carbon films, and templated carbon.

  9. Advanced lubrication systems and materials. Final report

    SciTech Connect

    Hsu, S.

    1998-05-07

    This report described the work conducted at the National Institute of Standards and Technology under an interagency agreement signed in September 1992 between DOE and NIST for 5 years. The interagency agreement envisions continual funding from DOE to support the development of fuel efficient, low emission engine technologies in terms of lubrication, friction, and wear control encountered in the development of advanced transportation technologies. However, in 1994, the DOE office of transportation technologies was reorganized and the tribology program was dissolved. The work at NIST therefore continued at a low level without further funding from DOE. The work continued to support transportation technologies in the development of fuel efficient, low emission engine development. Under this program, significant progress has been made in advancing the state of the art of lubrication technology for advanced engine research and development. Some of the highlights are: (1) developed an advanced high temperature liquid lubricant capable of sustaining high temperatures in a prototype heat engine; (2) developed a novel liquid lubricant which potentially could lower the emission of heavy duty diesel engines; (3) developed lubricant chemistries for ceramics used in the heat engines; (4) developed application maps for ceramic lubricant chemistry combinations for design purpose; and (5) developed novel test methods to screen lubricant chemistries for automotive air-conditioning compressors lubricated by R-134a (Freon substitute). Most of these findings have been reported to the DOE program office through Argonne National Laboratory who manages the overall program. A list of those reports and a copy of the report submitted to the Argonne National Laboratory is attached in Appendix A. Additional reports have also been submitted separately to DOE program managers. These are attached in Appendix B.

  10. Rapid Generation of Superheated Steam Using a Water-containing Porous Material

    NASA Astrophysics Data System (ADS)

    Mori, Shoji; Okuyama, Kunito

    Heat treatment by superheated steam has been utilized in several industrial fields including sterilization, desiccation, and cooking. In particular, cooking by superheated steam is receiving increased attention because it has advantages of reducing the salt and fat contents in foods as well as suppressing the oxidation of vitamin C and fat. In this application, quick startup and cut-off responses are required. Most electrically energized steam generators require a relatively long time to generate superheated steam due to the large heat capacities of the water in container and of the heater. Zhao and Liao (2002) introduced a novel process for rapid vaporization of subcooled liquid, in which a low-thermal-conductivity porous wick containing water is heated by a downward-facing grooved heating block in contact with the upper surface of the wick structure. They showed that saturated steam is generated within approximately 30 seconds from room-temperature water at a heat flux 41.2 kW⁄m2. In order to quickly generate superheated steam of approximately 300°C, which is required for cooking, the heat capacity of the heater should be as small as possible and the imposed heat flux should be so high enough that the porous wick is able to dry out in the vicinity of the contact with the heater and that the resulting heater temperature becomes much higher than the saturation temperature. The present paper proposes a simple structured generator to quickly produce superheated steam. Only a fine wire heater is contacted spirally on the inside wall in a hollow porous material. The start-up, cut-off responses and the rate of energy conversion for input power are investigated experimentally. Superheated steam of 300°C is produced in approximately 19 seconds from room-temperature water for an input power of 300 W. The maximum rate of energy conversion in the steady state is approximately 0.9.

  11. Atmospheric methane removal by methane-oxidizing bacteria immobilized on porous building materials.

    PubMed

    Ganendra, Giovanni; De Muynck, Willem; Ho, Adrian; Hoefman, Sven; De Vos, Paul; Boeckx, Pascal; Boon, Nico

    2014-04-01

    Biological treatment using methane-oxidizing bacteria (MOB) immobilized on six porous carrier materials have been used to mitigate methane emission. Experiments were performed with different MOB inoculated in building materials at high (~20 % (v/v)) and low (~100 ppmv) methane mixing ratios. Methylocystis parvus in autoclaved aerated concrete (AAC) exhibited the highest methane removal rate at high (28.5 ± 3.8 μg CH₄ g⁻¹ building material h⁻¹) and low (1.7 ± 0.4 μg CH₄ g⁻¹ building material h⁻¹) methane mixing ratio. Due to the higher volume of pores with diameter >5 μm compared to other materials tested, AAC was able to adsorb more bacteria which might explain for the higher methane removal observed. The total methane and carbon dioxide-carbon in the headspace was decreased for 65.2 ± 10.9 % when M. parvus in Ytong was incubated for 100 h. This study showed that immobilized MOB on building materials could be used to remove methane from the air and also act as carbon sink.

  12. Governing equations for multiphase heat and mass transfer in hygroscopic porous media with applications to clothing materials

    NASA Astrophysics Data System (ADS)

    Gibson, Phillip

    1994-11-01

    Whitaker's theory of coupled heat and mass transfer through porous media was modified to include hygroscopic porous materials which can absorb liquid into the solid matrix. The system of equations described in this report should make it possible to evaluate the time-dependent transport properties of hygroscopic and non-hygroscopic clothing materials by including many important factors which are usually ignored in the analysis of heat and mass transfer through textile materials. The set of equations allows for the unsteady capillary wicking of sweat through fabric structure, condensation and evaporation of sweat within various layers of the clothing system, forced gas phase convection through the porous structure of a textile layer, and the swelling and shrinkage of fibers and yarns as they absorb/desorb liquid water and water vapor.

  13. Iterated linear comparison bounds for viscoplastic porous materials with “ellipsoidal” microstructures

    NASA Astrophysics Data System (ADS)

    Agoras, M.; Ponte Castañeda, P.

    2013-03-01

    Analytical estimates are obtained for the effective constitutive response of porous viscoplastic materials consisting of aligned ellipsoidal voids that are distributed randomly with "ellipsoidal" symmetry in the matrix material. These estimates are obtained by means of a novel iterative homogenization strategy recently proposed by Ponte Castañeda (2012), and can be shown to be bounds for certain classes of multi-scale microstructures. By design, the resulting constitutive model agrees exactly with the earlier "variational linear comparison" model at the first iteration (N=1), and provides estimates that get progressively more accurate as the number of iterations increases (N→∞), especially for high-triaxiality loading conditions, and low porosity and strain-rate sensitivity. However, in practice, a small number of iterations (N≈10) is sufficient to get very accurate results. It is important to emphasize that, unlike other models that have been proposed in the literature, the new model requires no fitting parameters, solely depending on the properties of the matrix phase and microstructural information, such as the porosity, the average void shape and orientation, as well as the generally different shape and orientation of their distribution. Results are given for the yield and gauge surfaces of ideally plastic and power-law viscoplastic porous materials for the special cases of aligned spheroidal and ellipsoidal voids, and the results are compared with available numerical results and with the results of other models. Compared to available numerical results, the new estimates are found to be quite accurate, while they also provide more flexibility than competing models in terms of the characterization of the microstructure. In particular, it was found that the effect of different shapes for the average pore shape and distribution on the yield surfaces of the porous materials can be significant at high triaxialities, even for very small porosities. In addition

  14. New Advance in SuperConducting Materials

    ScienceCinema

    None

    2016-07-12

    Superconducting materials will transform the world's electrical infrastructure, saving billions of dollars once the technical details and installation are in place. At Los Alamos National Laborator...  

  15. Advanced diffusion studies with isotopically controlled materials

    SciTech Connect

    Bracht, Hartmut A.; Silvestri, Hughes H.; Haller, Eugene E.

    2004-11-14

    The use of enriched stable isotopes combined with modern epitaxial deposition and depth profiling techniques enables the preparation of material heterostructures, highly appropriate for self- and foreign-atom diffusion experiments. Over the past decade we have performed diffusion studies with isotopically enriched elemental and compound semiconductors. In the present paper we highlight our recent results and demonstrate that the use of isotopically enriched materials ushered in a new era in the study of diffusion in solids which yields greater insight into the properties of native defects and their roles in diffusion. Our approach of studying atomic diffusion is not limited to semiconductors and can be applied also to other material systems. Current areas of our research concern the diffusion in the silicon-germanium alloys and glassy materials such as silicon dioxide and ion conducting silicate glasses.

  16. Materials of construction for advanced coal conversion systems

    SciTech Connect

    Nangia, V.K.

    1982-01-01

    This book describes materials of construction, and materials problems for equipment used in advanced coal conversion systems. The need for cost effective industrial operation is always a prime concern, particularly in this age of energy consciousness. Industry is continually seeking improved materials for more efficient systems. The information presented here is intended to be of use in the design and planning of these systems. Coal conversion and utilization impose severe demands on construction materials because of high temperature, high pressure, corrosive/erosive, and other hostile environmental factors. Successful economic development of these processes can be achieved only to the extent that working materials can withstand increasingly more aggressive operating conditions. The book, which reviews present and past work on the behavior of materials in the environments of advanced coal conversion systems, is divided into three parts: atmospheric fluidized bed combustion, coal gasification and liquefaction, and advanced power systems.

  17. Monodisperse porous silicon spheres as anode materials for lithium ion batteries.

    PubMed

    Wang, Wei; Favors, Zachary; Ionescu, Robert; Ye, Rachel; Bay, Hamed Hosseini; Ozkan, Mihrimah; Ozkan, Cengiz S

    2015-03-05

    Highly monodisperse porous silicon nanospheres (MPSSs) are synthesized via a simple and scalable hydrolysis process with subsequent surface-protected magnesiothermic reduction. The spherical nature of the MPSSs allows for a homogenous stress-strain distribution within the structure during lithiation and delithiation, which dramatically improves the electrochemical stability. To fully extract the real performance of the MPSSs, carbon nanotubes (CNTs) were added to enhance the electronic conductivity within the composite electrode structure, which has been verified to be an effective way to improve the rate and cycling performance of anodes based on nano-Si. The Li-ion battery (LIB) anodes based on MPSSs demonstrate a high reversible capacity of 3105 mAh g(-1). In particular, reversible Li storage capacities above 1500 mAh g(-1) were maintained after 500 cycles at a high rate of C/2. We believe this innovative approach for synthesizing porous Si-based LIB anode materials by using surface-protected magnesiothermic reduction can be readily applied to other types of SiOx nano/microstructures.

  18. Test Method To Quantify The Wicking Properties Of Porous Insulation Materials Designed To Prevent Interstitial Condensation

    NASA Astrophysics Data System (ADS)

    Binder, Andrea; Zirkelbach, Daniel; Künzel, Hartwig

    2010-05-01

    Applying an interior insulation often is the only option for a thermal retrofit, especially when heritage buildings are concerned. In doing so, the original construction becomes colder in winter and interstitial condensation may occur. The common way to avoid harmful condensation beneath the interior insulation of the external wall is the installation of a vapor barrier. Since such a barrier works both ways, it may adversely affect the drying potential of the wall during the warmer seasons. One way to avoid the problems described is the installation of an interior insulation system without a vapor barrier to the inside. Here, the effect of capillary transport in porous hydrophilic media is used to conduct condensing moisture away from the wall/insulation interface back to the surface in contact with the indoor air. Following an increasing demand, several water wicking insulation materials (e.g. Calcium-silicate, Autoclave Aerated Concrete based mineral foam, hydrophilic Glass fiber, Cellulose fiber) have appeared on the market. In the past, different methods have been developed to measure and describe the liquid transport properties of hydrophilic porous media. However, the evaluation of the moisture transport mechanisms and their efficiency in this special field of implementation is very complex because of the interacting vapor- and liquid moisture transfer processes. Therefore, there is no consensus yet on its determination and quantification.

  19. Electrohydrodynamic bubbling: an alternative route to fabricate porous structures of silk fibroin based materials.

    PubMed

    Ekemen, Zeynep; Ahmad, Zeeshan; Stride, Eleanor; Kaplan, David; Edirisinghe, Mohan

    2013-05-13

    Conventional fabrication techniques and structures employed in the design of silk fibroin (SF) based porous materials provide only limited control over pore size and require several processing stages. In this study, it is shown that, by utilizing electrohydrodynamic bubbling, not only can new hollow spherical structures of SF be formed in a single step by means of bubbles, but the resulting bubbles can serve as pore generators when dehydrated. The bubble characteristics can be controlled through simple adjustments to the processing parameters. Bubbles with diameters in the range of 240-1000 μm were fabricated in controlled fashion. FT-IR characterization confirmed that the rate of air infused during processing enhanced β-sheet packing in SF at higher flow rates. Dynamic mechanical analysis also demonstrated a correlation between air flow rate and film tensile strength. Results indicate that electrohydrodynamically generated SF and their composite bubbles can be employed as new tools to generate porous structures in a controlled manner with a range of potential applications in biocoatings and tissue engineering scaffolds.

  20. Monodisperse Porous Silicon Spheres as Anode Materials for Lithium Ion Batteries

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Favors, Zachary; Ionescu, Robert; Ye, Rachel; Bay, Hamed Hosseini; Ozkan, Mihrimah; Ozkan, Cengiz S.

    2015-03-01

    Highly monodisperse porous silicon nanospheres (MPSSs) are synthesized via a simple and scalable hydrolysis process with subsequent surface-protected magnesiothermic reduction. The spherical nature of the MPSSs allows for a homogenous stress-strain distribution within the structure during lithiation and delithiation, which dramatically improves the electrochemical stability. To fully extract the real performance of the MPSSs, carbon nanotubes (CNTs) were added to enhance the electronic conductivity within the composite electrode structure, which has been verified to be an effective way to improve the rate and cycling performance of anodes based on nano-Si. The Li-ion battery (LIB) anodes based on MPSSs demonstrate a high reversible capacity of 3105 mAh g-1. In particular, reversible Li storage capacities above 1500 mAh g-1 were maintained after 500 cycles at a high rate of C/2. We believe this innovative approach for synthesizing porous Si-based LIB anode materials by using surface-protected magnesiothermic reduction can be readily applied to other types of SiOx nano/microstructures.

  1. Monodisperse Porous Silicon Spheres as Anode Materials for Lithium Ion Batteries

    PubMed Central

    Wang, Wei; Favors, Zachary; Ionescu, Robert; Ye, Rachel; Bay, Hamed Hosseini; Ozkan, Mihrimah; Ozkan, Cengiz S.

    2015-01-01

    Highly monodisperse porous silicon nanospheres (MPSSs) are synthesized via a simple and scalable hydrolysis process with subsequent surface-protected magnesiothermic reduction. The spherical nature of the MPSSs allows for a homogenous stress-strain distribution within the structure during lithiation and delithiation, which dramatically improves the electrochemical stability. To fully extract the real performance of the MPSSs, carbon nanotubes (CNTs) were added to enhance the electronic conductivity within the composite electrode structure, which has been verified to be an effective way to improve the rate and cycling performance of anodes based on nano-Si. The Li-ion battery (LIB) anodes based on MPSSs demonstrate a high reversible capacity of 3105 mAh g−1. In particular, reversible Li storage capacities above 1500 mAh g−1 were maintained after 500 cycles at a high rate of C/2. We believe this innovative approach for synthesizing porous Si-based LIB anode materials by using surface-protected magnesiothermic reduction can be readily applied to other types of SiOx nano/microstructures. PMID:25740298

  2. Advanced organic composite materials for aircraft structures: Future program

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Revolutionary advances in structural materials have been responsible for revolutionary changes in all fields of engineering. These advances have had and are still having a significant impact on aircraft design and performance. Composites are engineered materials. Their properties are tailored through the use of a mix or blend of different constituents to maximize selected properties of strength and/or stiffness at reduced weights. More than 20 years have passed since the potentials of filamentary composite materials were identified. During the 1970s much lower cost carbon filaments became a reality and gradually designers turned from boron to carbon composites. Despite progress in this field, filamentary composites still have significant unfulfilled potential for increasing aircraft productivity; the rendering of advanced organic composite materials into production aircraft structures was disappointingly slow. Why this is and research and technology development actions that will assist in accelerating the application of advanced organic composites to production aircraft is discussed.

  3. Advanced Materials and Solids Analysis Research Core (AMSARC)

    EPA Science Inventory

    The Advanced Materials and Solids Analysis Research Core (AMSARC), centered at the U.S. Environmental Protection Agency's (EPA) Andrew W. Breidenbach Environmental Research Center in Cincinnati, Ohio, is the foundation for the Agency's solids and surfaces analysis capabilities. ...

  4. Advances in glazing materials for windows

    SciTech Connect

    Not Available

    1994-11-01

    No one type of glazing is suitable for every application. Many materials are available that serve different purposes. Moreover, consumers may discover that they need two types of glazing for a home because of the directions that the windows face and the local climate. To make wise purchases, consumers should first examine their heating and cooling needs and prioritize desired features such as daylighting, solar heating, shading, ventilation, and aesthetic value. Research and development into types of glazing have created a new generation of materials that offer improved window efficiency and performance for consumers. While this new generation of glazing materials quickly gains acceptance in the marketplace, the research and development of even more efficient technology continues.

  5. Lignin-Derived Advanced Carbon Materials

    DOE PAGES

    Chatterjee, Sabornie; Saito, Tomonori

    2015-11-16

    Lignin is a highly abundant source of renewable carbon that can be considered as a valuable sustainable source of biobased materials. By applying specific pretreatments and manufacturing methods, it has been found that lignin can be converted into a variety of value-added carbon materials. However, the physical and chemical heterogeneities of lignin complicate its use as a feedstock. Herein, we discuss the lignin manufacturing process, the effects of pretreatments and manufacturing methods on the properties of product lignin, and structure–property relationships in various applications of lignin-derived carbon materials, such as carbon fibers, carbon mats, activated carbons, carbon films, and templatedmore » carbon.« less

  6. A colloidoscope of colloid-based porous materials and their uses.

    PubMed

    Phillips, Katherine R; England, Grant T; Sunny, Steffi; Shirman, Elijah; Shirman, Tanya; Vogel, Nicolas; Aizenberg, Joanna

    2016-01-21

    Nature evolved a variety of hierarchical structures that produce sophisticated functions. Inspired by these natural materials, colloidal self-assembly provides a convenient way to produce structures from simple building blocks with a variety of complex functions beyond those found in nature. In particular, colloid-based porous materials (CBPM) can be made from a wide variety of materials. The internal structure of CBPM also has several key attributes, namely porosity on a sub-micrometer length scale, interconnectivity of these pores, and a controllable degree of order. The combination of structure and composition allow CBPM to attain properties important for modern applications such as photonic inks, colorimetric sensors, self-cleaning surfaces, water purification systems, or batteries. This review summarizes recent developments in the field of CBPM, including principles for their design, fabrication, and applications, with a particular focus on structural features and materials' properties that enable these applications. We begin with a short introduction to the wide variety of patterns that can be generated by colloidal self-assembly and templating processes. We then discuss different applications of such structures, focusing on optics, wetting, sensing, catalysis, and electrodes. Different fields of applications require different properties, yet the modularity of the assembly process of CBPM provides a high degree of tunability and tailorability in composition and structure. We examine the significance of properties such as structure, composition, and degree of order on the materials' functions and use, as well as trends in and future directions for the development of CBPM.

  7. Accelerated tissue integration into porous materials by immobilizing basic fibroblast growth factor using a biologically safe three-step reaction.

    PubMed

    Kakinoki, Sachiro; Sakai, Yusuke; Fujisato, Toshia; Yamaoka, Tetsuji

    2015-12-01

    Soft tissue integration into a porous structure is important to prevent bacterial infection of percutaneous devices and improve tissue regeneration using porous scaffolds. Here, basic fibroblast growth factor (bFGF) was immobilized on porous polymer materials using a mild and biologically safe three-step reaction: (1) modification with a novel surface-modification peptide (penta-lysine-mussel adhesive sequence, which reacts with various matrices), (2) electrostatic binding of heparin with introduced penta-lysine, and (3) biologically specific binding of bFGF to heparin. Porous polyethylene specimens (PPSs) (D = 6.0 mm, H = 2.0 mm) with a good size for tissue integration were selected as a base material, immobilized with bFGF, and subcutaneously implanted into mice. Half of the unmodified PPSs extruded out of the body on day 112 postimplantation; however, the three-step reaction completely prevented sample rejection. Tissue integration was greatly accelerated by immobilizing bFGF. Direct physical coating of bFGF on PPS resulted in greater immobilization but lesser tissue integration than that after the three-step bFGF immobilization, indicating that heparin binds and enhances bFGF efficacy. This three-step bFGF immobilization reaction will be applicable to various polymeric, metallic, and ceramic materials and is a simple strategy to integrate tissue on porous medical devices or scaffolds for tissue regeneration. PMID:26034014

  8. Porous-structured Cu2O/TiO2 nanojunction material toward efficient CO2 photoreduction

    NASA Astrophysics Data System (ADS)

    Xu, Hua; Ouyang, Shuxin; Liu, Lequan; Wang, Defa; Kako, Tetsuya; Ye, Jinhua

    2014-04-01

    Porous-structured Cu2O/TiO2 nanojunction material is successfully fabricated by a facile method via loading Cu2O nanoparticles on the network of a porous TiO2 substrate. The developed Cu2O/TiO2 nanojunction material has a size of several nanometers, in which the p-type Cu2O and n-type TiO2 nanoparticles are closely contacted with each other. The well designed nanojunction structure is beneficial for the charge separation in the photocatalytic reaction. Meanwhile, the porous structure of the Cu2O/TiO2 nanojunction can facilitate the CO2 adsorption and offer more reaction active sites. Most importantly, the gas-phase CO2 photoreduction tests reveal that our developed porous-structured Cu2O/TiO2 nanojunction material exhibits marked photocatalytic activity in the CH4 evolution, about 12, 9, and 7.5 times higher than the pure TiO2, Pt-TiO2, and commercial Degussa P25 TiO2 powders, respectively. The greatly enhanced activity can be attributed to the well designed nanojunction structure combined with the porous structure, which can simultaneously enhance the charge separation efficiency and facilitate the CO2 adsorption.

  9. Effect of sintering conditions on the microstructural and mechanical characteristics of porous magnesium materials prepared by powder metallurgy.

    PubMed

    Čapek, Jaroslav; Vojtěch, Dalibor

    2014-02-01

    There has recently been an increased demand for porous magnesium materials in many applications, especially in the medical field. Powder metallurgy appears to be a promising approach for the preparation of such materials. Many works have dealt with the preparation of porous magnesium; however, the effect of sintering conditions on material properties has rarely been investigated. In this work, we investigated porous magnesium samples that were prepared by powder metallurgy using ammonium bicarbonate spacer particles. The effects of the purity of the argon atmosphere and sintering time on the microstructure (SEM, EDX and XRD) and mechanical behaviour (universal loading machine and Vickers hardness tester) of porous magnesium were studied. The porosities of the prepared samples ranged from 24 to 29 vol.% depending on the sintering conditions. The purity of atmosphere played a significant role when the sintering time exceeded 6h. Under a gettered argon atmosphere, a prolonged sintering time enhanced diffusion connections between magnesium particles and improved the mechanical properties of the samples, whereas under a technical argon atmosphere, oxidation at the particle surfaces caused deterioration in the mechanical properties of the samples. These results suggest that a refined atmosphere is required to improve the mechanical properties of porous magnesium.

  10. Accelerated tissue integration into porous materials by immobilizing basic fibroblast growth factor using a biologically safe three-step reaction.

    PubMed

    Kakinoki, Sachiro; Sakai, Yusuke; Fujisato, Toshia; Yamaoka, Tetsuji

    2015-12-01

    Soft tissue integration into a porous structure is important to prevent bacterial infection of percutaneous devices and improve tissue regeneration using porous scaffolds. Here, basic fibroblast growth factor (bFGF) was immobilized on porous polymer materials using a mild and biologically safe three-step reaction: (1) modification with a novel surface-modification peptide (penta-lysine-mussel adhesive sequence, which reacts with various matrices), (2) electrostatic binding of heparin with introduced penta-lysine, and (3) biologically specific binding of bFGF to heparin. Porous polyethylene specimens (PPSs) (D = 6.0 mm, H = 2.0 mm) with a good size for tissue integration were selected as a base material, immobilized with bFGF, and subcutaneously implanted into mice. Half of the unmodified PPSs extruded out of the body on day 112 postimplantation; however, the three-step reaction completely prevented sample rejection. Tissue integration was greatly accelerated by immobilizing bFGF. Direct physical coating of bFGF on PPS resulted in greater immobilization but lesser tissue integration than that after the three-step bFGF immobilization, indicating that heparin binds and enhances bFGF efficacy. This three-step bFGF immobilization reaction will be applicable to various polymeric, metallic, and ceramic materials and is a simple strategy to integrate tissue on porous medical devices or scaffolds for tissue regeneration.

  11. A bipotential-based limit analysis and homogenization of ductile porous materials with non-associated Drucker-Prager matrix

    NASA Astrophysics Data System (ADS)

    Cheng, Long; Jia, Yun; Oueslati, Abdelbacet; de Saxcé, Géry; Kondo, Djimedo

    2015-04-01

    In Gurson's footsteps, different authors have proposed macroscopic plastic models for porous solid with pressure-sensitive dilatant matrix obeying the normality law (associated materials). The main objective of the present paper is to extend this class of models to porous materials in the context of non-associated plasticity. This is the case of Drucker-Prager matrix for which the dilatancy angle is different from the friction one, and classical limit analysis theory cannot be applied. For such materials, the second last author has proposed a relevant modeling approach based on the concept of bipotential, a function of both dual variables, the plastic strain rate and stress tensors. On this ground, after recalling the basic elements of the Drucker-Prager model, we present the corresponding variational principles and the extended limit analysis theorems. Then, we formulate a new variational approach for the homogenization of porous materials with a non-associated matrix. This is implemented by considering the hollow sphere model with a non-associated Drucker-Prager matrix. The proposed procedure delivers a closed-form expression of the macroscopic bifunctional from which the criterion and a non-associated flow rule are readily obtained for the porous material. It is shown that these general results recover several available models as particular cases. Finally, the established results are assessed and validated by comparing their predictions to those obtained from finite element computations carried out on a cell representing the considered class of materials.

  12. ADVANCED ABRASION RESISTANT MATERIALS FOR MINING

    SciTech Connect

    Ludtka, G.M.

    2004-04-08

    The high-density infrared (HDI) transient-liquid coating (TLC) process was successfully developed and demonstrated excellent, enhanced (5 times higher than the current material and process) wear performance for the selected functionally graded material (FGM) coatings under laboratory simulated, in-service conditions. The mating steel component exhibited a wear rate improvement of approximately one and a half (1.5) times. After 8000 cycles of wear testing, the full-scale component testing demonstrated that the coating integrity was still excellent. Little or no spalling was observed to occur.

  13. Advance Abrasion Resistant Materials for Mining

    SciTech Connect

    Mackiewicz-Ludtka, G.

    2004-06-01

    The high-density infrared (HDI) transient-liquid coating (TLC) process was successfully developed and demonstrated excellent, enhanced (5 times higher than the current material and process) wear performance for the selected functionally graded material (FGM) coatings under laboratory simulated, in-service conditions. The mating steel component exhibited a wear rate improvement of approximately one and a half (1.5) times. After 8000 cycles of. wear testing, the full-scale component testing demonstrated that the coating integrity was still excellent. Little or no spalling was observed to occur.

  14. Fabrication of Advanced Thermoelectric Materials by Hierarchical Nanovoid Generation

    NASA Technical Reports Server (NTRS)

    Choi, Sang Hyouk (Inventor); Park, Yeonjoon (Inventor); Chu, Sang-Hyon (Inventor); Elliott, James R. (Inventor); King, Glen C. (Inventor); Kim, Jae-Woo (Inventor); Lillehei, Peter T. (Inventor); Stoakley, Diane M. (Inventor)

    2011-01-01

    A novel method to prepare an advanced thermoelectric material has hierarchical structures embedded with nanometer-sized voids which are key to enhancement of the thermoelectric performance. Solution-based thin film deposition technique enables preparation of stable film of thermoelectric material and void generator (voigen). A subsequent thermal process creates hierarchical nanovoid structure inside the thermoelectric material. Potential application areas of this advanced thermoelectric material with nanovoid structure are commercial applications (electronics cooling), medical and scientific applications (biological analysis device, medical imaging systems), telecommunications, and defense and military applications (night vision equipments).

  15. Porous carbon materials synthesized using IRMOF-3 and furfuryl alcohol as precursor

    NASA Astrophysics Data System (ADS)

    Deka, Pemta Tia; Ediati, Ratna

    2016-03-01

    IRMOF-3 crystals have been synthesized using solvothermal method by adding zinc nitrate hexahydrate with 2-amino-1,4-benzenedicarboxylic acid in N'N-dimethylformamide (DMF) at 100°C for 24 (note as IR-24) and 72 h (note as IR-72). The obtained crystals were characterized using X-ray Diffraction (XRD), SEM (Scanning Electron Microscopy) and Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX), FTIR and Isothermal adsorption-desorption N2. The diffractogram solids synthesized show characteristic peak at 2θ 6.8, 9.6 and 13.7°. SEM micrograph show cubic shape of IRMOF-3 crystal. Based on FTIR characterization, IRMOF-3 appear at wavelength (1691,46; 1425,3; 1238,21; 1319,22 dan 3504,42)cm-1. The Isotherm of crystal IRMOF-3 at heating time 24 h and 72 h are type IV. The surface area of IR-24 and IR-72 are respectively 24,758 m2/g and 29,139 m2/g with its dominant mesopores. Carbonaceous materials has been successfully synthesized using IR-24, IR-72 and furfuryl alcohol (FA) as second carbon precursor with variation of carbonation temperature 550, 700 and 850°C. The XRD result from both carbonaceous materials show formation of amorphous carbon and caharacteristic peak of ZnO oxide. Micrograph SEM show that carbonaceous materials have cubic shape as IRMOF-3 and SEM-EDX result indicate Zn and nitrogen content of these materials has decrease until temperature 850°C. Porous carbon using IR-24 and FA (notes as C-24) has increased surface area with higher carbonation temperature. The highest surface area is 1495,023 m2/g. Total pore volume and pore size of C-24 from low to high temperature respectively as (0,338; 0,539 and 1,598) cc/g; (0,107; 0,152 and 0,610) cc/g. Porous carbon using IR-72 and FA (notes as C-72) has smaller surface area than C-24 but its also increased during higher carbonation heating. The highest surface area is 1029,668 m2/g.The total pore volume and pore size of these carbon materials from low to high temperature respectively as (0,390; 0

  16. Evaluation of advanced materials. Final report

    SciTech Connect

    Wright, I.G.; Clauer, A.H.; Shetty, D.K.; Tucker, T.R.; Stropki, J.T.

    1982-11-18

    Cemented tungsten carbides with a binder level in the range of 5 to 6 percent exhibited the best resistance to erosion for this class of materials. Other practical cermet meterials were diamond - Si/SiC, Al/sub 2/O/sub 3/-B/sub 4/C-Cr, and B/sub 4/C-Co. SiAlON exhibited erosion resistance equivalent to the best WC-cermet. The only coating system to show promise of improved erosion resistance was CVD TiB/sub 2/ on cemented TiB/sub 2/-Ni. Cracking and/or spalling of a TiC coating and a proprietary TMT coating occurred in the standard slurry erosion test. Ranking of cemented tungsten carbide materials in the laboratory erosion test was the same as that found in service in the Wilsonville pilot plant. Specimens from the Fort Lewis pilot plant which performed well in service exhibited low erosion in the laboratory test. A substitute slurry, was found to be 2 to 4 times more erosive than the coal-derived slurry 8 wt% solids. Ranking of materials in the substitute slurry was nearly identical to that in the coal-derived slurry. Three modes of erosion were: ductile cutting; elastic-plastic indentation and fracture; and intergranular fracture. Erosion of a given material was closely related to its microstructure. In the substitute slurry, the angle-dependence of erosion of two forms of SiC, hot-pressed and sintered, were similar, but the sintered material eroded slower. Laser fusing of preplaced powder mixtures can produce cermet-like structures with potential for erosive and sliding wear resistance. TiC particles in Stellite 6 matrix proved less prone to cracking than WC particles in the same matrix. 74 figures, 14 tables.

  17. New Carbon-Based Porous Materials with Increased Heats of Adsorption for Hydrogen Storage

    SciTech Connect

    Snurr, Randall Q.; Hupp, Joseph T.; Kanatzidis, Mercouri G.; Nguyen, SonBinh T.

    2014-11-03

    Hydrogen fuel cell vehicles are a promising alternative to internal combustion engines that burn gasoline. A significant challenge in developing fuel cell vehicles is to store enough hydrogen on-board to allow the same driving range as current vehicles. One option for storing hydrogen on vehicles is to use tanks filled with porous materials that act as “sponges” to take up large quantities of hydrogen without the need for extremely high pressures. The materials must meet many requirements to make this possible. This project aimed to develop two related classes of porous materials to meet these requirements. All materials were synthesized from molecular constituents in a building-block approach, which allows for the creation of an incredibly wide variety of materials in a tailorable fashion. The materials have extremely high surface areas, to provide many locations for hydrogen to adsorb. In addition, they were designed to contain cations that create large electric fields to bind hydrogen strongly but not too strongly. Molecular modeling played a key role as a guide to experiment throughout the project. A major accomplishment of the project was the development of a material with record hydrogen uptake at cryogenic temperatures. Although the ultimate goal was materials that adsorb large quantities of hydrogen at room temperature, this achievement at cryogenic temperatures is an important step in the right direction. In addition, there is significant interest in applications at these temperatures. The hydrogen uptake, measured independently at NREL was 8.0 wt %. This is, to the best of our knowledge, the highest validated excess hydrogen uptake reported to date at 77 K. This material was originally sketched on paper based on a hypothesis that extended framework struts would yield materials with excellent hydrogen storage properties. However, before starting the synthesis, we used molecular modeling to assess the performance of the material for hydrogen uptake

  18. Three-dimensional Aerographite-GaN hybrid networks: Single step fabrication of porous and mechanically flexible materials for multifunctional applications

    NASA Astrophysics Data System (ADS)

    Schuchardt, Arnim; Braniste, Tudor; Mishra, Yogendra K.; Deng, Mao; Mecklenburg, Matthias; Stevens-Kalceff, Marion A.; Raevschi, Simion; Schulte, Karl; Kienle, Lorenz; Adelung, Rainer; Tiginyanu, Ion

    2015-03-01

    Three dimensional (3D) elastic hybrid networks built from interconnected nano- and microstructure building units, in the form of semiconducting-carbonaceous materials, are potential candidates for advanced technological applications. However, fabrication of these 3D hybrid networks by simple and versatile methods is a challenging task due to the involvement of complex and multiple synthesis processes. In this paper, we demonstrate the growth of Aerographite-GaN 3D hybrid networks using ultralight and extremely porous carbon based Aerographite material as templates by a single step hydride vapor phase epitaxy process. The GaN nano- and microstructures grow on the surface of Aerographite tubes and follow the network architecture of the Aerographite template without agglomeration. The synthesized 3D networks are integrated with the properties from both, i.e., nanoscale GaN structures and Aerographite in the form of flexible and semiconducting composites which could be exploited as next generation materials for electronic, photonic, and sensors applications.

  19. Three-dimensional Aerographite-GaN hybrid networks: single step fabrication of porous and mechanically flexible materials for multifunctional applications.

    PubMed

    Schuchardt, Arnim; Braniste, Tudor; Mishra, Yogendra K; Deng, Mao; Mecklenburg, Matthias; Stevens-Kalceff, Marion A; Raevschi, Simion; Schulte, Karl; Kienle, Lorenz; Adelung, Rainer; Tiginyanu, Ion

    2015-03-06

    Three dimensional (3D) elastic hybrid networks built from interconnected nano- and microstructure building units, in the form of semiconducting-carbonaceous materials, are potential candidates for advanced technological applications. However, fabrication of these 3D hybrid networks by simple and versatile methods is a challenging task due to the involvement of complex and multiple synthesis processes. In this paper, we demonstrate the growth of Aerographite-GaN 3D hybrid networks using ultralight and extremely porous carbon based Aerographite material as templates by a single step hydride vapor phase epitaxy process. The GaN nano- and microstructures grow on the surface of Aerographite tubes and follow the network architecture of the Aerographite template without agglomeration. The synthesized 3D networks are integrated with the properties from both, i.e., nanoscale GaN structures and Aerographite in the form of flexible and semiconducting composites which could be exploited as next generation materials for electronic, photonic, and sensors applications.

  20. Photocatalytic Properties of Porous Silicon Nanowires.

    PubMed

    Qu, Yongquan; Zhong, Xing; Li, Yujing; Liao, Lei; Huang, Yu; Duan, Xiangfeng

    2010-01-01

    Porous silicon nanowires are synthesized through metal assisted wet-chemical etch of highly-doped silicon wafer. The resulted porous silicon nanowires exhibit a large surface area of 337 m(2)·g(-1) and a wide spectrum absorption across the entire ultraviolet, visible and near infrared regime. We further demonstrate that platinum nanoparticles can be loaded onto the surface of the porous silicon nanowires with controlled density. These combined advancements make the porous silicon nanowires an interesting material for photocatalytic applications. We show that the porous silicon nanowires and platinum nanoparticle loaded porous silicon nanowires can be used as effective photocatalysts for photocatalytic degradation of organic dyes and toxic pollutants under visible irradiation, and thus are of significant interest for organic waste treatment and environmental remediation.

  1. Advances in electrode materials for AMTEC

    NASA Astrophysics Data System (ADS)

    Ryan, M. A.; Williams, R. M.; Lara, L.; Fiebig, B. G.; Cortez, R. H.; Kisor, A. K.; Shields, V. B.; Homer, M. L.

    2001-02-01

    A mixed conducting electrode for the Alkali Metal Thermal to Electric Converter (AMTEC) has been made and tested. The electrode is made from a slurry of metal and TiO2 powders which is applied to the electrolyte and fired to sinter the electrode material. During the first 48-72 hours of operation in a SETC, the electrode takes up Na from low pressure sodium vapor to make a metal-Na-Ti-O compound. This compound is electronically conducting and ionically conducting to sodium; electronic conduction is also provided by the metal in the electrode. With a mixed conducting electrode made from robust, low vapor pressure materials, the promise for improved performance and lifetime is high. .

  2. Polymers Advance Heat Management Materials for Vehicles

    NASA Technical Reports Server (NTRS)

    2013-01-01

    For 6 years prior to the retirement of the Space Shuttle Program, the shuttles carried an onboard repair kit with a tool for emergency use: two tubes of NOAX, or "good goo," as some people called it. NOAX flew on all 22 flights following the Columbia accident, and was designed to repair damage that occurred on the exterior of the shuttle. Bill McMahon, a structural materials engineer at Marshall Space Flight Center says NASA needed a solution for the widest range of possible damage to the shuttle s exterior thermal protection system. "NASA looked at several options in early 2004 and decided on a sealant. Ultimately, NOAX performed the best and was selected," he says. To prove NOAX would work effectively required hundreds of samples manufactured at Marshall and Johnson, and a concerted effort from various NASA field centers. Johnson Space Center provided programmatic leadership, testing, tools, and crew training; Glenn Research Center provided materials analysis; Langley Research Center provided test support and led an effort to perform large patch repairs; Ames Research Center provided additional testing; and Marshall provided further testing and the site of NOAX manufacturing. Although the sealant never had to be used in an emergency situation, it was tested by astronauts on samples of reinforced carbon-carbon (RCC) during two shuttle missions. (RCC is the thermal material on areas of the shuttle that experience the most heat, such as the nose cone and wing leading edges.) The material handled well on orbit, and tests showed the NOAX patch held up well on RCC.

  3. PREFACE: Advanced Materials for Demanding Applications

    NASA Astrophysics Data System (ADS)

    McMillan, Alison; Schofield, Stephen; Kelly, Michael

    2015-02-01

    This was a special conference. It was small enough (60+ delegates) but covering a wide range of topics, under a broad end-use focussed heading. Most conferences today either have hundreds or thousands of delegates or are small and very focussed. The topics ranged over composite materials, the testing of durability aspects of materials, and an eclectic set of papers on radar screening using weak ionized plasmas, composites for microvascular applications, composites in space rockets, and materials for spallation neutron sources etc. There were several papers of new characterisation techniques and, very importantly, several papers that started with the end-user requirements leading back into materials selection. In my own area, there were three talks about the technology for the ultra-precise positioning of individual atoms, donors, and complete monolayers to take modern electronics and optoelectronics ideas closer to the market place. The President of the Institute opened with an experience-based talk on translating innovative technology into business. Everyone gave a generous introduction to bring all-comers up to speed with the burning contemporary issues. Indeed, I wish that a larger cohort of first-year engineering PhD students were present to see the full gamut of what takes a physics idea to a success in the market place. I would urge groups to learn from Prof Alison McMillan (a Vice President of the Institute of Physics) and Steven Schofield, to set up conferences of similar scale and breadth. I took in more than I do from mega-meetings, and in greater depth. Professor Michael Kelly Department of Engineering University of Cambridge

  4. Breakthrough and future: nanoscale controls of compositions, morphologies, and mesochannel orientations toward advanced mesoporous materials.

    PubMed

    Yamauchi, Yusuke; Suzuki, Norihiro; Radhakrishnan, Logudurai; Wang, Liang

    2009-01-01

    Currently, ordered mesoporous materials prepared through the self-assembly of surfactants have attracted growing interests owing to their special properties, including uniform mesopores and a high specific surface area. Here we focus on fine controls of compositions, morphologies, mesochannel orientations which are important factors for design of mesoporous materials with new functionalities. This Review describes our recent progress toward advanced mesoporous materials. Mesoporous materials now include a variety of inorganic-based materials, for example, transition-metal oxides, carbons, inorganic-organic hybrid materials, polymers, and even metals. Mesoporous metals with metallic frameworks can be produced by using surfactant-based synthesis with electrochemical methods. Owing to their metallic frameworks, mesoporous metals with high electroconductivity and high surface areas hold promise for a wide range of potential applications, such as electronic devices, magnetic recording media, and metal catalysts. Fabrication of mesoporous materials with controllable morphologies is also one of the main subjects in this rapidly developing research field. Mesoporous materials in the form of films, spheres, fibers, and tubes have been obtained by various synthetic processes such as evaporation-mediated direct templating (EDIT), spray-dried techniques, and collaboration with hard-templates such as porous anodic alumina and polymer membranes. Furthermore, we have developed several approaches for orientation controls of 1D mesochannels. The macroscopic-scale controls of mesochannels are important for innovative applications such as molecular-scale devices and electrodes with enhanced diffusions of guest species.

  5. Cladding and Duct Materials for Advanced Nuclear Recycle Reactors

    SciTech Connect

    Allen, Todd R.; Busby, Jeremy T; Klueh, Ronald L; Maloy, S; Toloczko, M

    2008-01-01

    The expanded use of nuclear energy without risk of nuclear weapons proliferation and with safe nuclear waste disposal is a primary goal of the Global Nuclear Energy Partnership (GNEP). To achieve that goal the GNEP is exploring advanced technologies for recycling spent nuclear fuel that do not separate pure plutonium, and advanced reactors that consume transuranic elements from recycled spent fuel. The GNEP s objectives will place high demands on reactor clad and structural materials. This article discusses the materials requirements of the GNEP s advanced nuclear recycle reactors program.

  6. Cladding and duct materials for advanced nuclear recycle reactors

    NASA Astrophysics Data System (ADS)

    Allen, T. R.; Busby, J. T.; Klueh, R. L.; Maloy, S. A.; Toloczko, M. B.

    2008-01-01

    The expanded use of nuclear energy without risk of nuclear weapons proliferation and with safe nuclear waste disposal is a primary goal of the Global Nuclear Energy Partnership (GNEP). To achieve that goal the GNEP is exploring advanced technologies for recycling spent nuclear fuel that do not separate pure plutonium, and advanced reactors that consume transuranic elements from recycled spent fuel. The GNEP’s objectives will place high demands on reactor clad and structural materials. This article discusses the materials requirements of the GNEP’s advanced nuclear recycle reactors program.

  7. Advanced Materials and Coatings for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    2004-01-01

    In the application area of aerospace tribology, researchers and developers must guarantee the highest degree of reliability for materials, components, and systems. Even a small tribological failure can lead to catastrophic results. The absence of the required knowledge of tribology, as Professor H.P. Jost has said, can act as a severe brake in aerospace vehicle systems-and indeed has already done so. Materials and coatings must be able to withstand the aerospace environments that they encounter, such as vacuum terrestrial, ascent, and descent environments; be resistant to the degrading effects of air, water vapor, sand, foreign substances, and radiation during a lengthy service; be able to withstand the loads, stresses, and temperatures encountered form acceleration and vibration during operation; and be able to support reliable tribological operations in harsh environments throughout the mission of the vehicle. This presentation id divided into two sections: surface properties and technology practice related to aerospace tribology. The first section is concerned with the fundamental properties of the surfaces of solid-film lubricants and related materials and coatings, including carbon nanotubes. The second is devoted to applications. Case studies are used to review some aspects of real problems related to aerospace systems to help engineers and scientists to understand the tribological issues and failures. The nature of each problem is analyzed, and the tribological properties are examined. All the fundamental studies and case studies were conducted at the NASA Glenn Research Center.

  8. Sound transmission through double panel constructions lined with elastic porous materials

    NASA Astrophysics Data System (ADS)

    Bolton, J. S.; Green, E. R.

    1986-07-01

    Attention is given to a theory governing one-dimensional wave motion in elastic porous materials which is capable of reproducing experimental transmission measurements for unfaced polyurethane foam layers. Calculations of the transmission loss of fuselage-like foam-lined double panels are presented and it is shown that the foam/panel boundary conditions have a large effect on the panel performance; a hybrid arrangement whereby the foam is bonded directly to one panel and separated from the other by a thin air gap appears to be the most advantageous under practical circumstances. With this configuratiom, the mass-air-mass resonance is minimized and increased low-frequency performance is offered.

  9. Combustion of porous energetic materials in the merged-flame regime

    SciTech Connect

    Margolis, S.B.; Williams, F.A.; Telengator, A.M.

    1996-02-01

    The structure and burning rate of an unconfined deflagration propagating through a porous energetic material is analyzed in the limit of merged condensed and gas-phase reaction zones. A global two-step reaction mechanism, applicable to certain types of degraded nitramine propellants and consisting of sequential condensed and gaseous steps, is postulated. Taking into account important effects due to multiphase flow and exploiting the limit of large activation energies, a theoretical analysis based on activation energy asymptotics leads to explicit formulas for the deflagration velocity in a specifically identified regime that is consistent with the merged-flame assumption. The results clearly indicate the influences of two-phase flow and the multiphase, multi-step chemistry on the deflagration structure and the burning rate, and define conditions that support the intrusion of the primary gas flame into the two-phase condensed decomposition region at the propellant surface.

  10. Separation of C2 Hydrocarbons by Porous Materials: Metal Organic Frameworks as Platform

    SciTech Connect

    Banerjee, Debasis; Liu, Jun; Thallapally, Praveen K.

    2014-12-22

    The effective separation of small hydrocarbon molecules (C1 – C4) is an important process for petroleum industry, determining the end price of many essential commodities in our daily lives. Current technologies for separation of these molecules rely on energy intensive fractional distillation processes at cryogenic temperature, which is particularly difficult because of their similar volatility. In retrospect, adsorptive separation using solid state adsorbents might be a cost effective alternative. Several types of solid state adsorbents (e.g. zeolite molecular sieves) were tested for separation of small hydrocarbon molecules as a function of pressure, temperature or vacuum. Among different types of plausible adsorbents, metal organic frameworks (MOFs), a class of porous, crystalline, inorganic-organic hybrid materials, is particularly promising. In this brief comment article, we discuss the separation properties of different types of solid state adsorbents, with a particular emphasis on MOF based adsorbents for separation of C2 hydrocarbon molecules.

  11. Percolating length scales from topological persistence analysis of micro-CT images of porous materials

    NASA Astrophysics Data System (ADS)

    Robins, Vanessa; Saadatfar, Mohammad; Delgado-Friedrichs, Olaf; Sheppard, Adrian P.

    2016-01-01

    Topological persistence is a powerful and general technique for characterizing the geometry and topology of data. Its theoretical foundations are over 15 years old and efficient computational algorithms are now available for the analysis of large digital images. We explain here how quantities derived from topological persistence relate to other measurements on porous materials such as grain and pore-size distributions, connectivity numbers, and the critical radius of a percolating sphere. The connections between percolation and topological persistence are explored in detail using data obtained from micro-CT images of spherical bead packings, unconsolidated sand packing, a variety of sandstones, and a limestone. We demonstrate how persistence information can be used to estimate the percolating sphere radius and to characterize the connectivity of the percolating cluster.

  12. Characterization of porous materials using combined small-angle X-ray and neutron scattering techniques

    SciTech Connect

    Hu, Naiping; Borkar, Neha; Kohls, Doug; Schaefer, Dale W.

    2014-09-24

    A combination of ultra small angle X-ray scattering (USAXS) and ultra small angle neutron scattering (USANS) is used to characterize porous materials. The analysis methods yield quantitative information, including the mean skeletal chord length, mean pore chord length, skeletal density, and composition. A mixed cellulose ester (MCE) membrane with a manufacturer-labeled pore size of 0.1 {mu}m was used as a model to elucidate the specifics of the method. Four approaches describing four specific scenarios (different known parameters and form of the scattering data) are compared. Pore chords determined using all four approaches are in good agreement with the scanning electron microscopy estimates but are larger than the manufacturer's nominal pore size. Our approach also gives the average chord of the skeletal solid (struts) of the membrane, which is also consistent for all four approaches. Combined data from USAXS and USANS gives the skeletal density and the strut composition.

  13. Investigations on deflagration to detonation transition in porous energetic materials. Final report

    SciTech Connect

    Stewart, D.S.

    1999-07-01

    The research carried out by this contract was part of a larger effort funded by LANL in the areas of deflagration to detonation in porous energetic materials (DDT) and detonation shock dynamics in high explosives (DSD). In the first three years of the contract the major focus was on DDT. However, some researchers were carried out on DSD theory and numerical implementation. In the last two years the principal focus of the contract was on DSD theory and numerical implementation. However, during the second period some work was also carried out on DDT. The paper discusses DDT modeling and DSD modeling. Abstracts are included on the following topics: modeling deflagration to detonation; DSD theory; DSD wave front tracking; and DSD program burn implementation.

  14. Measuring sound absorption properties of porous materials using a calibrated volume velocity source

    NASA Astrophysics Data System (ADS)

    Arenas, Jorge P.; Darmendrail, Luis

    2013-10-01

    Measurement of acoustic properties of sound-absorbing materials has been the source of much investigation that has produced practical measuring methods. In particular, the measurement of the normal incidence sound absorption coefficient is commonly done using a well-known configuration of a tube carrying a plane wave. The sound-absorbing coefficient is calculated from the surface impedance measured on a sample of material. Therefore, a direct measurement of the impedance requires knowing the ratio between the sound pressure and the volume velocity. However, the measurement of volume velocity is not straightforward in practice and many methods have been proposed including complex transducers, laser vibrometry, accelerometers and calibrated volume velocity sources. In this paper, a device to directly measure the acoustic impedance of a sample of sound-absorbing material is presented. The device uses an internal microphone in a small cavity sealed by a loudspeaker and a second microphone mounted in front of this source. The calibration process of the device and the limitations of the method are also discussed and measurement examples are presented. The accuracy of the device was assessed by direct comparison with the standardized method. The proposed measurement method was tested successfully with various types of commercial acoustic porous materials.

  15. Diffusion-mediated nuclear spin phase decoherence in cylindrically porous materials

    NASA Astrophysics Data System (ADS)

    Knight, Michael J.; Kauppinen, Risto A.

    2016-08-01

    In NMR or MRI of complex materials, including biological tissues and porous materials, magnetic susceptibility differences within the material result in local magnetic field inhomogeneities, even if the applied magnetic field is homogeneous. Mobile nuclear spins move though the inhomogeneous field, by translational diffusion and other mechanisms, resulting in decoherence of nuclear spin phase more rapidly than transverse relaxation alone. The objective of this paper is to simulate this diffusion-mediated decoherence and demonstrate that it may substantially reduce coherence lifetimes of nuclear spin phase, in an anisotropic fashion. We do so using a model of cylindrical pores within an otherwise homogeneous material, and calculate the resulting magnetic field inhomogeneities. Our simulations show that diffusion-mediated decoherence in a system of parallel cylindrical pores is anisotropic, with coherence lifetime minimised when the array of cylindrical pores is perpendicular to B0. We also show that this anisotropy of coherence lifetime is reduced if the orientations of cylindrical pores are disordered within the system. In addition we characterise the dependence on B0, the magnetic susceptibility of the cylindrical pores relative to the surroundings, the diffusion coefficient and cylinder wall thickness. Our findings may aid in the interpretation of NMR and MRI relaxation data.

  16. Velocity measurements of inert porous materials driven by infrared-laser-ablated thin-film titanium

    NASA Astrophysics Data System (ADS)

    Bedeaux, Brett C.; Trott, Wayne M.; Castañeda, Jaime N.

    2010-02-01

    This article presents and interprets a series of experiments performed to measure the velocity of four inert low-density porous materials that were accelerated by an ablated thin-film titanium metal, created by vaporizing a 250-nm-thick layer of titanium with a high-energy, Q-switched, pulsed, and 1.054 μm neodymium-glass laser. Inert powder materials were chosen to match, among other characteristics, the morphology of energetic materials under consideration for use in detonator applications. The observed behavior occurs near the thin-film titanium ablation layer, through complex physical mechanisms, including laser absorption in the metal layer, ablation and formation of confined plasma that is a blackbody absorber of the remaining photon energy, and vaporization of the remaining titanium metal. One-dimensional hydrodynamic modeling provided a basis of comparison with the measured velocities. We found, as predicted in wave-propagation-code modeling, that an Asay foil can indicate total momentum of the driven material that is mechanically softer (lower in shock impedance) than the foil. The key conclusion is that the specific impulse delivered by the laser transfers a corresponding momentum to soft, organic power columns that are readily compacted. Impulse from the laser is less efficient in transferring momentum to hard inorganic particles that are less readily compacted.

  17. A Porous TiAl6V4 Implant Material for Medical Application.

    PubMed

    Deing, Axel; Luthringer, Bérengère; Laipple, Daniel; Ebel, Thomas; Willumeit, Regine

    2014-01-01

    Increased durability of permanent TiAl6V4 implants still remains a requirement for the patient's well-being. One way to achieve a better bone-material connection is to enable bone "ingrowth" into the implant. Therefore, a new porous TiAl6V4 material was produced via metal injection moulding (MIM). Specimens with four different porosities were produced using gas-atomised spherical TiAl6V4 with different powder particle diameters, namely, "Small" (<45 μm), "Medium" (45-63 μm), "Mix" (90% 125-180 μm + 10% <45 μm), and "Large" (125-180 μm). Tensile tests, compression tests, and resonant ultrasound spectroscopy (RUS) were used to analyse mechanical properties. These tests revealed an increasing Young's modulus with decreasing porosity; that is, "Large" and "Mix" exhibit mechanical properties closer to bone than to bulk material. By applying X-ray tomography (3D volume) and optical metallographic methods (2D volume and dimensions) the pores were dissected. The pore analysis of the "Mix" and "Large" samples showed pore volumes between 29% and 34%, respectively, with pore diameters ranging up to 175 μm and even above 200 μm for "Large." Material cytotoxicity on bone cell lines (SaOs-2 and MG-63) and primary cells (human bone-derived cells, HBDC) was studied by MTT assays and highlighted an increasing viability with higher porosity.

  18. Advanced new materials with various applications

    NASA Astrophysics Data System (ADS)

    Radu-Claudiu, Fierascu; Rodica-Mariana, Ion; Irina, Dumitriu

    2009-01-01

    Nanotechnology is the manufacture and science of materials with at least one dimension in the nanometer scale [1]. Many nanomaterials have novel chemical and biological properties and most of them are not naturally occurring. Carbon nanotubes (CNTs) are an example of a carbon-based nanomaterial which has won enormous popularity in nanotechnology for its unique properties and applications [2]. CNTs have highly desirable physicochemical properties for use in commercial, environmental and medical sectors. The inclusion of CNTs to improve the quality and performance of many widely used products, as well as potentially in medicine, will dramatically affect occupational and public exposure to CNT based nanomaterials in the near future [3].

  19. Advanced AE Techniques in Composite Materials Research

    NASA Technical Reports Server (NTRS)

    Prosser, William H.

    1996-01-01

    Advanced, waveform based acoustic emission (AE) techniques have been successfully used to evaluate damage mechanisms in laboratory testing of composite coupons. An example is presented in which the initiation of transverse matrix cracking was monitored. In these tests, broad band, high fidelity acoustic sensors were used to detect signals which were then digitized and stored for analysis. Analysis techniques were based on plate mode wave propagation characteristics. This approach, more recently referred to as Modal AE, provides an enhanced capability to discriminate and eliminate noise signals from those generated by damage mechanisms. This technique also allows much more precise source location than conventional, threshold crossing arrival time determination techniques. To apply Modal AE concepts to the interpretation of AE on larger composite specimens or structures, the effects of modal wave propagation over larger distances and through structural complexities must be well characterized and understood. To demonstrate these effects, measurements of the far field, peak amplitude attenuation of the extensional and flexural plate mode components of broad band simulated AE signals in large composite panels are discussed. These measurements demonstrated that the flexural mode attenuation is dominated by dispersion effects. Thus, it is significantly affected by the thickness of the composite plate. Furthermore, the flexural mode attenuation can be significantly larger than that of the extensional mode even though its peak amplitude consists of much lower frequency components.

  20. Combustion synthesis of advanced composite materials

    NASA Technical Reports Server (NTRS)

    Moore, John J.

    1993-01-01

    Self-propagating high temperature (combustion) synthesis (SHS), has been investigated as a means of producing both dense and expanded (foamed) ceramic and ceramic-metal composites, ceramic powders and whiskers. Several model exothermic combustion synthesis reactions were used to establish the importance of certain reaction parameters, e.g., stoichiometry, green density, combustion mode, particle size, etc. on the control of the synthesis reaction, product morphology and properties. The use of an in situ liquid infiltration technique and the effect of varying the reactants and their stoichiometry to provide a range of reactant and product species i.e., solids, liquids and gases, with varying physical properties e.g., volatility and thermal conductivity, on the microstructure and morphology of synthesized composite materials is discussed. Conducting the combustion synthesis reaction in a reactive gas environment to take advantage of the synergistic effects of combustion synthesis and vapor phase transport is also examined.

  1. Characterization of advanced preprocessed materials (Hydrothermal)

    SciTech Connect

    Rachel Emerson; Garold Gresham

    2012-09-01

    The initial hydrothermal treatment parameters did not achieve the proposed objective of this effort; the reduction of intrinsic ash in the corn stover. However, liquid fractions from the 170°C treatments was indicative that some of the elements routinely found in the ash that negatively impact the biochemical conversion processes had been removed. After reviewing other options for facilitating ash removal, sodium-citrate (chelating agent) was included in the hydrothermal treatment process, resulting in a 69% reduction in the physiological ash. These results indicated that chelation –hydrothermal treatment is one possible approach that can be utilized to reduce the overall ash content of feedstock materials and having a positive impact on conversion performance.

  2. Advances in computational studies of energy materials.

    PubMed

    Catlow, C R A; Guo, Z X; Miskufova, M; Shevlin, S A; Smith, A G H; Sokol, A A; Walsh, A; Wilson, D J; Woodley, S M

    2010-07-28

    We review recent developments and applications of computational modelling techniques in the field of materials for energy technologies including hydrogen production and storage, energy storage and conversion, and light absorption and emission. In addition, we present new work on an Sn2TiO4 photocatalyst containing an Sn(II) lone pair, new interatomic potential models for SrTiO3 and GaN, an exploration of defects in the kesterite/stannite-structured solar cell absorber Cu2ZnSnS4, and report details of the incorporation of hydrogen into Ag2O and Cu2O. Special attention is paid to the modelling of nanostructured systems, including ceria (CeO2, mixed Ce(x)O(y) and Ce2O3) and group 13 sesquioxides. We consider applications based on both interatomic potential and electronic structure methodologies; and we illustrate the increasingly quantitative and predictive nature of modelling in this field. PMID:20566517

  3. A transfer-matrix approach for estimating the characteristic impedance and wave numbers of limp and rigid porous materials

    PubMed

    Song; Bolton

    2000-03-01

    A method for evaluating the acoustical properties of homogeneous and isotropic porous materials that may be modeled as fluids having complex properties is described here. To implement the procedure, a conventional, two-microphone standing wave tube was modified to include: a new sample holder; a section downstream of the sample holder that accommodated a second pair of microphone holders and an approximately anechoic termination. Sound-pressure measurements at two upstream and two downstream locations were then used to estimate the two-by-two transfer matrix of porous material samples. The experimental transfer matrix method has been most widely used in the past to measure the acoustical properties of silencer system components. That procedure was made more efficient here by taking advantage of the reciprocal nature of sound transmission through homogeneous and isotropic porous layers. The transfer matrix of a homogeneous and isotropic, rigid or limp porous layer can easily be used to identify the material's characteristic impedance and wave number, from which other acoustical quantities of interest can be calculated. The procedure has been used to estimate the acoustical properties of a glass fiber material: good agreement was found between the estimated acoustical properties and those predicted by using the formulas of Delany and Bazley.

  4. Porous graphene-based material as an efficient metal free catalyst for the oxidative dehydrogenation of ethylbenzene to styrene.

    PubMed

    Diao, Jiangyong; Liu, Hongyang; Wang, Jia; Feng, Zhenbao; Chen, Tong; Miao, Changxi; Yang, Weimin; Su, Dang Sheng

    2015-02-25

    Reduced porous graphene oxide as a metal free catalyst was selected for the oxidative dehydrogenation of ethylbenzene to styrene. It showed the best catalytic performance compared with other carbon materials (routinely reduced graphene oxide, graphite powder and oxidized carbon nanotubes) and commercial iron oxide. PMID:25625943

  5. Materials and light thermal structures research for advanced space exploration

    NASA Technical Reports Server (NTRS)

    Thornton, Earl A.; Starke, Edgar A., Jr.; Herakovich, Carl T.

    1991-01-01

    The Light Thermal Structures Center at the University of Virginia sponsors educational and research programs focused on the development of reliable, lightweight structures to function in hostile thermal environments. Technology advances in materials and design methodology for light thermal structures will contribute to improved space vehicle design concepts with attendant weight savings. This paper highlights current research activities in three areas relevant to space exploration: low density, high temperature aluminum alloys, composite materials, and structures with thermal gradients. Advances in the development of new aluminum-lithium alloys and mechanically alloyed aluminum alloys are described. Material properties and design features of advanced composites are highlighted. Research studies in thermal structures with temperature gradients include inelastic panel buckling and thermally induced unstable oscillations. Current and future research is focused on the integration of new materials with applications to structural components with thermal gradients.

  6. A novel multiple batch extraction test to assess contaminant mobilization from porous waste materials

    NASA Astrophysics Data System (ADS)

    Iden, S. C.; Durner, W.; Delay, M.; Frimmel, F. H.

    2009-04-01

    Contaminated porous materials, like soils, dredged sediments or waste materials must be tested before they can be used as filling materials in order to minimize the risk of groundwater pollution. We applied a multiple batch extraction test at varying liquid-to-solid (L/S) ratios to a demolition waste material and a municipal waste incineration product and investigated the release of chloride, sulphate, sodium, copper, chromium and dissolved organic carbon from both waste materials. The liquid phase test concentrations were used to estimate parameters of a relatively simple mass balance model accounting for equilibrium partitioning. The model parameters were estimated within a Bayesian framework by applying an efficient MCMC sampler and the uncertainties of the model parameters and model predictions were quantified. We tested isotherms of the linear, Freundlich and Langmuir type and selected the optimal isotherm model by use of the Deviance Information Criterion (DIC). Both the excellent fit to the experimental data and a comparison between the model-predicted and independently measured concentrations at the L/S ratios of 0.25 and 0.5 L/kg demonstrate the applicability of the model for almost all studied substances and both waste materials. We conclude that batch extraction tests at varying L/S ratios provide, at moderate experimental cost, a powerful complement to established test designs like column leaching or single batch extraction tests. The method constitutes an important tool in risk assessments, because concentrations at soil water contents representative for the field situation can be predicted from easier-to-obtain test concentrations at larger L/S ratios. This helps to circumvent the experimental difficulties of the soil saturation extract and eliminates the need to apply statistical approaches to predict such representative concentrations which have been shown to suffer dramatically from poor correlations.

  7. Unoxidized porous Si as an isolation material for mixed-signal integrated circuit applications

    NASA Astrophysics Data System (ADS)

    Kim, Han-Su; Xie, Ya-Hong; DeVincentis, Marc; Itoh, Tatsuo; Jenkins, Keith A.

    2003-04-01

    An isolation technology for radio frequency (rf) applications based on unoxidized porous Si (PS) is demonstrated. This study examines all the important issues pertinent to incorporating PS with Si very-large-scale integration (VLSI) technology, where PS is used as a semi-insulating material. Specifically, the issues on rf isolation performance of PS as a function of porosity [from coplanar waveguide (CPW) line measurements] and PS thickness (from on-chip inductors) and the stress generated from incorporating PS regions by anodization are discussed in detail. CPW line measurements show that the relative dielectric constant of PS films decreases from 9 to 3 with increasing porosity from 24% to 78%. PS is a very low loss material with loss tangent <0.001 at 20 GHz when its porosity is above 51%. rf crosstalk through a Si substrate can be reduced to that through air by inserting a PS trench between noise generating circuit and noise sensing circuit. On-chip spiral inductors fabricated on top of PS regions of through-the-wafer thickness have Qmax of about 29 at 7 GHz and resonant frequency higher than 20 GHz. With the additional advantage of planar topography and mechanical integrity, we show that unoxidized PS is an outstanding material for rf isolation in Si VLSI.

  8. Giant Negative Area Compressibility Tunable in a Soft Porous Framework Material.

    PubMed

    Cai, Weizhao; Gładysiak, Andrzej; Anioła, Michalina; Smith, Vincent J; Barbour, Leonard J; Katrusiak, Andrzej

    2015-07-29

    A soft porous material [Zn(L)2(OH)2]n·Guest (where L is 4-(1H-naphtho[2,3-d]imidazol-1-yl)benzoate, and Guest is water or methanol) exhibits the strongest ever observed negative area compressibility (NAC), an extremely rare property, as at hydrostatic pressure most materials shrink in all directions and few expand in one direction. This is the first NAC reported in metal-organic frameworks (MOFs), and its magnitude, clearly visible and by far the highest of all known materials, can be reversibly tuned by exchanging guests adsorbed from hydrostatic fluids. This counterintuitive strong NAC of [Zn(L)2(OH)2]n·Guest arises from the interplay of flexible [-Zn-O(H)-]n helices with layers of [-Zn-L-]4 quadrangular puckered rings comprising large channel voids. The compression of helices and flattening of puckered rings combine to give a giant piezo-mechanical response, applicable in ultrasensitive sensors and actuators. The extrinsic NAC response to different hydrostatic fluids is due to varied host-guest interactions affecting the mechanical strain within the range permitted by exceptionally high flexibility of the framework.

  9. Porous ovalbumin scaffolds with tunable properties: a resource-efficient biodegradable material for tissue engineering applications.

    PubMed

    Luo, Baiwen; Choong, Cleo

    2015-01-01

    Natural materials are promising alternatives to synthetic materials used in tissue engineering applications as they have superior biocompatibility and promote better cell attachment and proliferation. Ovalbumin, a natural polymer found in avian egg white, is an example of a nature-derived material. Despite the availability and reported biocompatibility of ovalbumin, limited research has been carried out to investigate the efficacy of ovalbumin-based scaffolds for adipose tissue engineering applications. Hence, the current study was carried out to investigate the effect of different crosslinkers on ovalbumin scaffold properties as first step towards the development of ovalbumin-based scaffolds for adipose tissue engineering applications. In this study, highly porous three-dimensional scaffolds were fabricated by using three different crosslinkers: glutaraldehyde, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and 1,4-butanediol diglycidyl ether. Results showed that the overall scaffold properties such as morphology, pore size and mechanical properties could be modulated based on the type and concentration of crosslinkers used during the fabrication process. Subsequently, the efficacy of the different scaffolds for supporting cell proliferation was investigated. In vitro degradation was also carried on for the best scaffold based on the mechanical and cellular results. Overall, this study is a demonstration of the viability of ovalbumin-based scaffolds as cell carriers for soft tissue engineering applications. PMID:25158688

  10. Porous ovalbumin scaffolds with tunable properties: a resource-efficient biodegradable material for tissue engineering applications.

    PubMed

    Luo, Baiwen; Choong, Cleo

    2015-01-01

    Natural materials are promising alternatives to synthetic materials used in tissue engineering applications as they have superior biocompatibility and promote better cell attachment and proliferation. Ovalbumin, a natural polymer found in avian egg white, is an example of a nature-derived material. Despite the availability and reported biocompatibility of ovalbumin, limited research has been carried out to investigate the efficacy of ovalbumin-based scaffolds for adipose tissue engineering applications. Hence, the current study was carried out to investigate the effect of different crosslinkers on ovalbumin scaffold properties as first step towards the development of ovalbumin-based scaffolds for adipose tissue engineering applications. In this study, highly porous three-dimensional scaffolds were fabricated by using three different crosslinkers: glutaraldehyde, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and 1,4-butanediol diglycidyl ether. Results showed that the overall scaffold properties such as morphology, pore size and mechanical properties could be modulated based on the type and concentration of crosslinkers used during the fabrication process. Subsequently, the efficacy of the different scaffolds for supporting cell proliferation was investigated. In vitro degradation was also carried on for the best scaffold based on the mechanical and cellular results. Overall, this study is a demonstration of the viability of ovalbumin-based scaffolds as cell carriers for soft tissue engineering applications.

  11. Advanced magneto-optical materials and devices

    NASA Astrophysics Data System (ADS)

    Kang, Shaoying

    The magneto-optical materials with both high Faraday rotation and high transmittance capabilities are greatly desired in high speed switches, isolators, and visible imaging systems. In this thesis work, new magneto-optical materials that possess both high Faraday effect and high transmittance in the visible range of the spectrum were studied and synthesized. New Bismuth iron gallium garnet thin-films (Bi3Fe4Ga 1O12, BIGG) have been successfully deposited on gadolinium gallium garnet substrates with a pulsed laser deposition technique in our lab. X-ray diffraction analyses have proven that the BIGG films are of good epitaxial quality with a lattice constant close to 12.61+/-0.01Á. The bandwidth of BIGG's transmittance spectrum has been extended and its left edge has been shifted about 50nm towards the shorter wavelengths relative to those of Bi3Fe5O12 (BIG) films. The BIGG film is more transparent than a BIG film although BIGG's Faraday rotation angle is slightly less than that of a BIG film. The figure of merit of the BIGG garnet film has reached 16.5°, which is about 1.8 times that of a typical BIG film. Currently, the switches using BIGG films were tested and a 2.4 ns response time had been reached with a phi1 mm circular aperture at the wavelength of 532 nm. Iron Borate (FeBO3) is another material that is far superior in terms of the transmittance in the visible spectrum at room temperature to most garnet materials. The FeBO3 is one of the orthoferrites with a large natural birefringence for the light propagated along the magnetization direction. The effect of birefringence on Faraday rotation reduced the maximum obtainable rotation. In order to eliminate the birefringence and further improve the transmittance, a high energy ball-milling technique was used to synthesize FeBO3 nanoparticles. Our numerical simulation shows the nanoparticles could eliminate the birefringence, and concurrently keep the intrinsic Faraday rotation. After milling and centrifuging

  12. Surface chemical deposition of advanced electronic materials

    NASA Astrophysics Data System (ADS)

    Bjelkevig, Cameron

    The focus of this work was to examine the direct plating of Cu on Ru diffusion barriers for use in interconnect technology and the substrate mediated growth of graphene on boron nitride for use in advanced electronic applications. The electrodeposition of Cu on Ru(0001) and polycrystalline substrates (with and without pretreatment in an iodine containing solution) has been studied by cyclic voltammetry (CV), current--time transient measurements (CTT), in situ electrochemical atomic force microscopy (EC-AFM), and X-ray photoelectron spectroscopy (XPS). The EC-AFM data show that at potentials near the OPD/UPD threshold, Cu crystallites exhibit pronounced growth anisotropy, with lateral dimensions greatly exceeding vertical dimensions. XPS measurements confirmed the presence and stability of adsorbed I on the Ru surface following pre-treatment in a KI/H2SO4 solution and following polarization to at least -200 mV vs. Ag/AgCl. CV data of samples pre-reduced in I-containing electrolyte exhibited a narrow Cu deposition peak in the overpotential region and a UPD peak. The kinetics of the electrodeposited Cu films was investigated by CTT measurements and applied to theoretical models of nucleation. The data indicated that a protective I adlayer may be deposited on an airexposed Ru electrode as the oxide surface is electrochemically reduced, and that this layer will inhibit reformation of an oxide during the Cu electroplating process. A novel method for epitaxial graphene growth directly on a dielectric substrate of systematically variable thickness was studied. Mono/multilayers of BN(111) were grown on Ru(0001) by atomic layer deposition (ALD), exhibiting a flat (non-nanomesh) R30(✓3x✓3) structure. BN(111) was used as a template for growth of graphene by chemical vapor deposition (CVD) of C2H4 at 1000 K. Characterization by LEED, Auger, STM/STS and Raman indicate the graphene is in registry with the BN substrate, and exhibits a HOPG-like 0 eV bandgap density

  13. SYNTHESIS AND CHARACTERIZATION OF ADVANCED MAGNETIC MATERIALS

    SciTech Connect

    Monica Sorescu

    2004-09-22

    The work described in this grant report was focused mainly on the properties of novel magnetic intermetallics. In the first project, we synthesized several 2:17 intermetallic compounds, namely Nd{sub 2}Fe{sub 15}Si{sub 2}, Nd{sub 2}Fe{sub 15}Al{sub 2}, Nd{sub 2}Fe{sub 15}SiAl and Nd{sub 2}Fe{sub 15}SiMn, as well as several 1:12 intermetallic compounds, such as NdFe{sub 10}Si{sub 2}, NdFe{sub 10}Al{sub 2}, NdFe{sub 10}SiAl and NdFe{sub 10}MnAl. In the second project, seven compositions of Nd{sub x}Fe{sub 100-x-y}B{sub y} ribbons were prepared by a melt spinning method with Nd and B content increasing from 7.3 and 3.6 to 11 and 6, respectively. The alloys were annealed under optimized conditions to obtain a composite material consisting of the hard magnetic Nd{sub 2}Fe{sub 14}B and soft magnetic {alpha}-Fe phases, typical of a spring magnet structure. In the third project, intermetallic compounds of the type Zr{sub 1}Cr{sub 1}Fe{sub 1}T{sub 0.8} with T = Al, Co and Fe were subjected to hydrogenation. In the fourth project, we performed three crucial experiments. In the first experiment, we subjected a mixture of Fe{sub 3}O{sub 4} and Fe (80-20 wt %) to mechanochemical activation by high-energy ball milling, for time periods ranging from 0.5 to 14 hours. In the second experiment, we ball-milled Fe{sub 3}O{sub 4}:Co{sup 2+} (x = 0.1) for time intervals between 2.5 and 17.5 hours. Finally, we exposed a mixture of Fe{sub 3}O{sub 4} and Co (80-20 wt %) to mechanochemical activation for time periods ranging from 0.5 to 10 hours. In all cases, the structural and magnetic properties of the systems involved were elucidated by X-ray diffraction (XRD), Moessbauer spectroscopy and hysteresis loop measurements. The four projects resulted in four papers, which were published in Intermetallics, IEEE Transactions on Magnetics, Journal of Materials Science Letters and Materials Chemistry and Physics. The contributions reveal for the first time in literature the effect of

  14. Fossil Energy Advanced Research and Technology Development Materials Program

    SciTech Connect

    Cole, N.C.; Judkins, R.R.

    1992-12-01

    Objective of this materials program is to conduct R and D on materials for fossil energy applications with focus on longer-term and generic needs of the various fossil fuel technologies. The projects are organized according to materials research areas: (1) ceramics, (2) new alloys: iron aluminides, advanced austenitics and chromium niobium alloys, and (3) technology development and transfer. Separate abstracts have been prepared.

  15. Simulation Toolkit for Renewable Energy Advanced Materials Modeling

    SciTech Connect

    Sides, Scott; Kemper, Travis; Larsen, Ross; Graf, Peter

    2013-11-13

    STREAMM is a collection of python classes and scripts that enables and eases the setup of input files and configuration files for simulations of advanced energy materials. The core STREAMM python classes provide a general framework for storing, manipulating and analyzing atomic/molecular coordinates to be used in quantum chemistry and classical molecular dynamics simulations of soft materials systems. The design focuses on enabling the interoperability of materials simulation codes such as GROMACS, LAMMPS and Gaussian.

  16. Advanced Industrial Materials (AIM) Program: Annual progress report FY 1995

    SciTech Connect

    1996-04-01

    In many ways, the Advanced Industrial Materials (AIM) Program underwent a major transformation in Fiscal Year 1995 and these changes have continued to the present. When the Program was established in 1990 as the Advanced Industrial Concepts (AIC) Materials Program, the mission was to conduct applied research and development to bring materials and processing technologies from the knowledge derived from basic research to the maturity required for the end use sectors for commercialization. In 1995, the Office of Industrial Technologies (OIT) made radical changes in structure and procedures. All technology development was directed toward the seven ``Vision Industries`` that use about 80% of industrial energy and generated about 90% of industrial wastes. The mission of AIM has, therefore, changed to ``Support development and commercialization of new or improved materials to improve productivity, product quality, and energy efficiency in the major process industries.`` Though AIM remains essentially a National Laboratory Program, it is essential that each project have industrial partners, including suppliers to, and customers of, the seven industries. Now, well into FY 1996, the transition is nearly complete and the AIM Program remains reasonably healthy and productive, thanks to the superb investigators and Laboratory Program Managers. This Annual Report for FY 1995 contains the technical details of some very remarkable work by the best materials scientists and engineers in the world. Areas covered here are: advanced metals and composites; advanced ceramics and composites; polymers and biobased materials; and new materials and processes.

  17. Integration of advanced nuclear materials separation processes

    SciTech Connect

    Jarvinen, G.D.; Worl, L.A.; Padilla, D.D.; Berg, J.M.; Neu, M.P.; Reilly, S.D.; Buelow, S.

    1998-12-31

    This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project has examined the fundamental chemistry of plutonium that affects the integration of hydrothermal technology into nuclear materials processing operations. Chemical reactions in high temperature water allow new avenues for waste treatment and radionuclide separation.Successful implementation of hydrothermal technology offers the potential to effective treat many types of radioactive waste, reduce the storage hazards and disposal costs, and minimize the generation of secondary waste streams. The focus has been on the chemistry of plutonium(VI) in solution with carbonate since these are expected to be important species in the effluent from hydrothermal oxidation of Pu-containing organic wastes. The authors investigated the structure, solubility, and stability of the key plutonium complexes. Installation and testing of flow and batch hydrothermal reactors in the Plutonium Facility was accomplished. Preliminary testing with Pu-contaminated organic solutions gave effluent solutions that readily met discard requirements. A new effort in FY 1998 will build on these promising initial results.

  18. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants.

    PubMed

    Gryshkov, Oleksandr; Klyui, Nickolai I; Temchenko, Volodymyr P; Kyselov, Vitalii S; Chatterjee, Anamika; Belyaev, Alexander E; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO2) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application. PMID:27524006

  19. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants.

    PubMed

    Gryshkov, Oleksandr; Klyui, Nickolai I; Temchenko, Volodymyr P; Kyselov, Vitalii S; Chatterjee, Anamika; Belyaev, Alexander E; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO2) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application.

  20. Advanced structural analysis of nanoporous materials by thermal response measurements.

    PubMed

    Oschatz, Martin; Leistner, Matthias; Nickel, Winfried; Kaskel, Stefan

    2015-04-01

    Thermal response measurements based on optical adsorption calorimetry are presented as a versatile tool for the time-saving and profound characterization of the pore structure of porous carbon-based materials. This technique measures the time-resolved temperature change of an adsorbent during adsorption of a test gas. Six carbide and carbon materials with well-defined nanopore architecture including micro- and/or mesopores are characterized by thermal response measurements based on n-butane and carbon dioxide as the test gases. With this tool, the pore systems of the model materials can be clearly distinguished and accurately analyzed. The obtained calorimetric data are correlated with the adsorption/desorption isotherms of the materials. The pore structures can be estimated from a single experiment due to different adsorption enthalpies/temperature increases in micro- and mesopores. Adsorption/desorption cycling of n-butane at 298 K/1 bar with increasing desorption time allows to determine the pore structure of the materials in more detail due to different equilibration times. Adsorption of the organic test gas at selected relative pressures reveals specific contributions of particular pore systems to the increase of the temperature of the samples and different adsorption mechanisms. The use of carbon dioxide as the test gas at 298 K/1 bar provides detailed insights into the ultramicropore structure of the materials because under these conditions the adsorption of this test gas is very sensitive to the presence of pores smaller than 0.7 nm. PMID:25773383

  1. Advances in photonics thermal management and packaging materials

    NASA Astrophysics Data System (ADS)

    Zweben, Carl

    2008-02-01

    Heat dissipation, thermal stresses, and cost are key packaging design issues for virtually all semiconductors, including photonic applications such as diode lasers, light-emitting diodes (LEDs), solid state lighting, photovoltaics, displays, projectors, detectors, sensors and laser weapons. Heat dissipation and thermal stresses affect performance and reliability. Copper, aluminum and conventional polymeric printed circuit boards (PCBs) have high coefficients of thermal expansion, which can cause high thermal stresses. Most traditional low-coefficient-of-thermal-expansion (CTE) materials like tungsten/copper, which date from the mid 20 th century, have thermal conductivities that are no better than those of aluminum alloys, about 200 W/m-K. There are an increasing number of low-CTE materials with thermal conductivities ranging between that of copper (400 W/m-K) and 1700 W/m-K, and many other new low-CTE materials with lower thermal conductivities. An important benefit of low-CTE materials is that they allow use of hard solders. Some advanced materials are low cost. Others have the potential to be low cost in high-volume production. High-thermal-conductivity materials enable higher power levels, potentially reducing the number of required devices. Advanced thermal materials can constrain PCB CTE and greatly increase thermal conductivity. This paper reviews traditional packaging materials and advanced thermal management materials. The latter provide the packaging engineer with a greater range of options than in the past. Topics include properties, status, applications, cost, using advanced materials to fix manufacturing problems, and future directions, including composites reinforced with carbon nanotubes and other thermally conductive materials.

  2. On the validity of the effective stress concept for assessing the strength of saturated porous materials: A homogenization approach

    NASA Astrophysics Data System (ADS)

    De Buhan, P.; Dormieux, L.

    1996-10-01

    The much debated question of whether the strength criterion of a fluid saturated porous medium, such as most geomaterials, can be expressed in terms of "effective stress," is critically examined in this paper using the yield design homogenization theory as an investigating tool. Adopting a periodic description of the saturated porous material at the microscopic level, where the fluid phase exerts a pressure on the solid matrix making up the skeleton, a general definition of the strength properties of the porous material at the macroscopic scale is given. While some situations are identified where the "effective stress principle," as classically formulated, remains appropriate, it is proved that for a frictional solid matrix, such a principle, even in its generalized form, is not relevant. Nevertheless, the dependence on the pore pressure can still be specified in a simple way, so that the complete knowledge of the criterion for any prescribed value of the pore pressure only requires determining the strength properties of the dry porous material. Moreover, the possibility of adopting sufficiently accurate approximations of the actual criterion by resorting to an effective stress formulation is discussed.

  3. A novel synthetic material for spinal fusion: a prospective clinical trial of porous bioactive titanium metal for lumbar interbody fusion.

    PubMed

    Fujibayashi, Shunsuke; Takemoto, Mitsuru; Neo, Masashi; Matsushita, Tomiharu; Kokubo, Tadashi; Doi, Kenji; Ito, Tatsuya; Shimizu, Akira; Nakamura, Takashi

    2011-09-01

    The objective of this study was to establish the efficacy and safety of porous bioactive titanium metal for use in a spinal fusion device, based on a prospective human clinical trial. A high-strength spinal interbody fusion device was manufactured from porous titanium metal. A bioactive surface was produced by simple chemical and thermal treatment. Five patients with unstable lumbar spine disease were treated surgically using this device in a clinical trial approved by our Ethics Review Committee and the University Hospital Medical Information Network. Clinical and radiological results were reported at the minimum follow-up period of 1 year. The optimal mechanical strength and interconnected structure of the porous titanium metal were adjusted for the device. The whole surface of porous titanium metal was treated uniformly and its bioactive ability was confirmed before clinical use. Successful bony union was achieved in all cases within 6 months without the need for autologous iliac crest bone grafting. Two specific findings including an anchoring effect and gap filling were evident radiologically. All clinical parameters improved significantly after the operation and no adverse effects were encountered during the follow-up period. Although a larger and longer-term follow-up clinical study is mandatory to reach any firm conclusions, the study results show that this porous bioactive titanium metal is promising material for a spinal fusion device.

  4. Deformation and Damage Studies for Advanced Structural Materials

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Advancements made in understanding deformation and damage of advanced structural materials have enabled the development of new technologies including the attainment of a nationally significant NASA Level 1 Milestone and the provision of expertise to the Shuttle Return to Flight effort. During this collaborative agreement multiple theoretical and experimental research programs, facilitating safe durable high temperature structures using advanced materials, have been conceived, planned, executed. Over 26 publications, independent assessments of structures and materials in hostile environments, were published within this agreement. This attainment has been recognized by 2002 Space Flight Awareness Team Award, 2004 NASA Group Achievement Award and 2003 and 2004 OAI Service Awards. Accomplishments in the individual research efforts are described as follows.

  5. Porous material based on spongy titanium granules: structure, mechanical properties, and osseointegration.

    PubMed

    Rubshtein, A P; Trakhtenberg, I Sh; Makarova, E B; Triphonova, E B; Bliznets, D G; Yakovenkova, L I; Vladimirov, A B

    2014-02-01

    A porous material has been produced by pressing spongy titanium granules with subsequent vacuum sintering. The material with porosity of more than 30% has an open system of interconnecting pores. The Young's modulus and 0.2% proof strength have been measured for the samples having 20-55% porosity. If the porosity is between 30 and 45%, the mechanical properties are determined by irregular shape of pores, which is due to spongy titanium granules. The experiment in vivo was performed on adult rabbits. Before surgery the implants were saturated with adherent autologous bone marrow cells. The implants were introduced into the defects formed in the condyles of tibias and femurs. Investigations of osseointegration of implants having 40% porosity showed that the whole system of pores was filled with mature bone tissue in 16 weeks after surgery. Neogenic bone tissue has an uneven surface formed by lacunas and craters indicative of active resorption and subsequent rearrangement (SEM examination). The bone tissue is pierced by neoformed vessels. Irregular-shaped pores with tortuous walls and numerous lateral channels going through the granules provide necessary conditions for the formation of functional bone tissue in the implant volume and the periimplant region. PMID:24411389

  6. A Versatile and Scalable Approach toward Robust Superhydrophobic Porous Materials with Excellent Absorbency and Flame Retardancy.

    PubMed

    Ruan, Changping; Shen, Mengxia; Ren, Xiaoyan; Ai, Kelong; Lu, Lehui

    2016-08-09

    The frequent oil spillages and the industrial discharge of organic contaminants have not only created severe environmental and ecological crises, but also cause a risk of fire and explosion. These environmental and safety issues emphasize the urgent need for materials that possess superior sorption capability and less flammability and thus can effectively and safely clean up the floating oils and water-insoluble organic compounds. Here we present the successful hydrophobic modification of the flame retardant melamine sponge with a commercial fluorosilicone, by using a facile one-step solvent-free approach and demonstrate that the resultant superhydrophobic sponge not only exhibits extraordinary absorption efficiency (including high capacity, superior selectivity, good recyclability, and simple recycling routes), but also retains excellent flame retardancy and robust stability. In comparison to conventional methods, which usually utilize massive organic solvents, the present approach does not involve any complicated process or sophisticated equipment nor generates any waste liquids, and thus is a more labor-saving, environment-friendly, energy-efficient and cost-effective strategy for the hydrophobic modification. Taking into account the critical role of hydrophobic porous materials, especially in the field of environmental remediation, the approach presented herein would be highly valuable for environmental remediation and industrial applications.

  7. Optical second-harmonic generation measurements of porous low-k dielectric materials

    NASA Astrophysics Data System (ADS)

    Atkin, Joanna; Shaw, Thomas; Laibowitz, Robert; Heinz, Tony

    2009-03-01

    Low-k dielectric materials based on porous carbon-doped oxides, with relative dielectric constants as low as 2.1, are widely used as thin insulating films in the microelectronics industry. Knowledge of these materials' basic electronic properties, such as energy gaps, barrier heights, and trap states, is essential for modeling their electrical leakage and stability characteristics. We use femtosecond laser pulses to probe the dynamics of charge-carrier transfer processes across Si/LKD interfacial barriers by optical second harmonic generation (SHG). Larger electric fields from multiphoton injection can be developed in Si/LKD systems compared to Si/SiO2, indicating a significantly higher density of traps in the LKD. This is consistent with previously reported measurements of trap density by photoinjection techniques^*. We will also discuss results on the dynamics of discharging and on the dependence of charging phenomena on layer thickness. ^*J. M. Atkin, D. Song, T. M. Shaw, E. Cartier, R. B. Laibowitz, and T. F. Heinz, J. Appl. Phys. 103, 094104 (2008).

  8. Technique for measurement of characteristic impedance and propagation constant for porous materials

    NASA Astrophysics Data System (ADS)

    Jung, Ki Won; Atchley, Anthony A.

    2005-09-01

    Knowledge of acoustic properties such as characteristic impedance and complex propagation constant is useful to characterize the acoustic behaviors of porous materials. Song and Bolton's four-microphone method [J. Acoust. Soc. Am. 107, 1131-1152 (2000)] is one of the most widely employed techniques. In this method two microphones are used to determine the complex pressure amplitudes for each side of a sample. Muehleisen and Beamer [J. Acoust. Soc. Am. 117, 536-544 (2005)] improved upon a four-microphone method by interchanging microphones to reduce errors due to uncertainties in microphone response. In this paper, a multiple microphone technique is investigated to reconstruct the pressure field inside an impedance tube. Measurements of the acoustic properties of a material having square cross-section pores is used to check the validity of the technique. The values of characteristic impedance and complex propagation constant extracted from the reconstruction agree well with predicted values. Furthermore, this technique is used in investigating the acoustic properties of reticulated vitreous carbon (RVC) in the range of 250-1100 Hz.

  9. A Versatile and Scalable Approach toward Robust Superhydrophobic Porous Materials with Excellent Absorbency and Flame Retardancy.

    PubMed

    Ruan, Changping; Shen, Mengxia; Ren, Xiaoyan; Ai, Kelong; Lu, Lehui

    2016-01-01

    The frequent oil spillages and the industrial discharge of organic contaminants have not only created severe environmental and ecological crises, but also cause a risk of fire and explosion. These environmental and safety issues emphasize the urgent need for materials that possess superior sorption capability and less flammability and thus can effectively and safely clean up the floating oils and water-insoluble organic compounds. Here we present the successful hydrophobic modification of the flame retardant melamine sponge with a commercial fluorosilicone, by using a facile one-step solvent-free approach and demonstrate that the resultant superhydrophobic sponge not only exhibits extraordinary absorption efficiency (including high capacity, superior selectivity, good recyclability, and simple recycling routes), but also retains excellent flame retardancy and robust stability. In comparison to conventional methods, which usually utilize massive organic solvents, the present approach does not involve any complicated process or sophisticated equipment nor generates any waste liquids, and thus is a more labor-saving, environment-friendly, energy-efficient and cost-effective strategy for the hydrophobic modification. Taking into account the critical role of hydrophobic porous materials, especially in the field of environmental remediation, the approach presented herein would be highly valuable for environmental remediation and industrial applications. PMID:27501762

  10. Acoustical properties of air-saturated porous material with periodically distributed dead-end pores.

    PubMed

    Leclaire, P; Umnova, O; Dupont, T; Panneton, R

    2015-04-01

    A theoretical and numerical study of the sound propagation in air-saturated porous media with straight main pores bearing lateral cavities (dead-ends) is presented. The lateral cavities are located at "nodes" periodically spaced along each main pore. The effect of periodicity in the distribution of the lateral cavities is studied, and the low frequency limit valid for the closely spaced dead-ends is considered separately. It is shown that the absorption coefficient and transmission loss are influenced by the viscous and thermal losses in the main pores as well as their perforation rate. The presence of long or short dead-ends significantly alters the acoustical properties of the material and can increase significantly the absorption at low frequencies (a few hundred hertz). These depend strongly on the geometry (diameter and length) of the dead-ends, on their number per node, and on the periodicity along the propagation axis. These effects are primarily due to low sound speed in the main pores and to thermal losses in the dead-end pores. The model predictions are compared with experimental results. Possible designs of materials of a few cm thicknesses displaying enhanced low frequency absorption at a few hundred hertz are proposed. PMID:25920830

  11. Porous Structures in Stacked, Crumpled and Pillared Graphene-Based 3D Materials

    PubMed Central

    Guo, Fei; Creighton, Megan; Chen, Yantao; Hurt, Robert; Külaots, Indrek

    2015-01-01

    Graphene, an atomically thin material with the theoretical surface area of 2600 m2g−1, has great potential in the fields of catalysis, separation, and gas storage if properly assembled into functional 3D materials at large scale. In ideal non-interacting ensembles of non-porous multilayer graphene plates, the surface area can be adequately estimated using the simple geometric law ~ 2600 m2g−1/N, where N is the number of graphene sheets per plate. Some processing operations, however, lead to secondary plate-plate stacking, folding, crumpling or pillaring, which give rise to more complex structures. Here we show that bulk samples of multilayer graphene plates stack in an irregular fashion that preserves the 2600/N surface area and creates regular slot-like pores with sizes that are multiples of the unit plate thickness. In contrast, graphene oxide deposits into films with massive area loss (2600 to 40 m2g−1) due to nearly perfect alignment and stacking during the drying process. Pillaring graphene oxide sheets by co-deposition of colloidal-phase particle-based spacers has the potential to partially restore the large monolayer surface. Surface areas as high as 1000 m2g−1 are demonstrated here through colloidal-phase deposition of graphene oxide with water-dispersible aryl-sulfonated ultrafine carbon black as a pillaring agent. PMID:26478597

  12. A Versatile and Scalable Approach toward Robust Superhydrophobic Porous Materials with Excellent Absorbency and Flame Retardancy

    NASA Astrophysics Data System (ADS)

    Ruan, Changping; Shen, Mengxia; Ren, Xiaoyan; Ai, Kelong; Lu, Lehui

    2016-08-01

    The frequent oil spillages and the industrial discharge of organic contaminants have not only created severe environmental and ecological crises, but also cause a risk of fire and explosion. These environmental and safety issues emphasize the urgent need for materials that possess superior sorption capability and less flammability and thus can effectively and safely clean up the floating oils and water-insoluble organic compounds. Here we present the successful hydrophobic modification of the flame retardant melamine sponge with a commercial fluorosilicone, by using a facile one-step solvent-free approach and demonstrate that the resultant superhydrophobic sponge not only exhibits extraordinary absorption efficiency (including high capacity, superior selectivity, good recyclability, and simple recycling routes), but also retains excellent flame retardancy and robust stability. In comparison to conventional methods, which usually utilize massive organic solvents, the present approach does not involve any complicated process or sophisticated equipment nor generates any waste liquids, and thus is a more labor-saving, environment-friendly, energy-efficient and cost-effective strategy for the hydrophobic modification. Taking into account the critical role of hydrophobic porous materials, especially in the field of environmental remediation, the approach presented herein would be highly valuable for environmental remediation and industrial applications.

  13. Measurement of the resistivity of porous materials with an alternating air-flow method.

    PubMed

    Dragonetti, Raffaele; Ianniello, Carmine; Romano, Rosario A

    2011-02-01

    Air-flow resistivity is a main parameter governing the acoustic behavior of porous materials for sound absorption. The international standard ISO 9053 specifies two different methods to measure the air-flow resistivity, namely a steady-state air-flow method and an alternating air-flow method. The latter is realized by the measurement of the sound pressure at 2 Hz in a small rigid volume closed partially by the test sample. This cavity is excited with a known volume-velocity sound source implemented often with a motor-driven piston oscillating with prescribed area and displacement magnitude. Measurements at 2 Hz require special instrumentation and care. The authors suggest an alternating air-flow method based on the ratio of sound pressures measured at frequencies higher than 2 Hz inside two cavities coupled through a conventional loudspeaker. The basic method showed that the imaginary part of the sound pressure ratio is useful for the evaluation of the air-flow resistance. Criteria are discussed about the choice of a frequency range suitable to perform simplified calculations with respect to the basic method. These criteria depend on the sample thickness, its nonacoustic parameters, and the measurement apparatus as well. The proposed measurement method was tested successfully with various types of acoustic materials.

  14. Lattice Boltzmann modeling of permeability in porous materials with partially percolating voxels.

    PubMed

    Li, Ruru; Yang, Y Sam; Pan, Jinxiao; Pereira, Gerald G; Taylor, John A; Clennell, Ben; Zou, Caineng

    2014-09-01

    A partial-bounce-back lattice Boltzmann model has been used to simulate flow on a lattice consisting of cubic voxels with a locally varying effective percolating fraction. The effective percolating fraction of a voxel is the total response to the partial-bounce-back techniques for porous media flow due to subvoxel fine structures. The model has been verified against known analytic solutions on two- and three-dimensional regular geometries, and has been applied to simulate flow and permeabilities of two real-world rock samples. This enables quantitative determination of permeability for problems where voxels cannot be adequately segmented as discrete compositions. The voxel compositions are represented as volume fractions of various material phases and void. The numerical results have shown that, for the tight-sandstone sample, the bulk permeability is sensitive to the effective percolating fraction of calcite. That is, the subvoxel flow paths in the calcite phase are important for bulk permeability. On the other hand, flow in the calcite phase in the sandstone sample makes an insignificant contribution to the bulk permeability. The calculated permeability value for the sandstone sample is up to two orders of magnitude greater than the tight sandstone. This model is generic and could be applied to other oil and gas reservoir media or to material samples.

  15. A theoretical approach of strain localization within thin planar bands in porous ductile materials

    NASA Astrophysics Data System (ADS)

    Leblond, Jean-Baptiste; Mottet, Gérard

    2008-01-01

    Propagation of cracks in ductile materials is well known to occur through two possible mechanisms: coalescence of cavities and formation of shear bands ('void sheet mechanism'). The classical Gurson-Tvergaard-Needleman (GTN) homogenized model for such materials incorporates some phenomenological modelling of coalescence, but not of formation of shear bands assisted by the presence of microvoids, and this generates a number of shortcomings. In order to solve these difficulties, this paper presents a unified model of both coalescence and formation of shear bands in porous plastic solids, including the possible couplings between the two. Both phenomena are viewed as expressions of the same basic effect, namely strain localization within thin planar bands, the only difference being the mode of deformation. The model is first developed assuming a periodic distribution of cavities, then critically assessed through comparison with some micromechanical numerical simulations based on the same assumption, and finally extended to the case of a random distribution of voids. To cite this article: J.-B. Leblond, G. Mottet, C. R. Mecanique 336 (2008).

  16. A mesomechanical analysis of the deformation and fracture in polycrystalline materials with ceramic porous coatings

    NASA Astrophysics Data System (ADS)

    Balokhonov, R. R.; Zinoviev, A. V.; Romanova, V. A.; Batukhtina, E. E.

    2015-10-01

    The special features inherent in the mesoscale mechanical behavior of a porous ceramic coating-steel substrate composite are investigated. Microstructure of the coated material is accounted for explicitly as initial conditions of a plane strain dynamic boundary-value problem solved by the finite difference method. Using a mechanical analogy method, a procedure for generating a uniform curvilinear finite difference computational mesh is developed to provide a more accurate description of the complex grain boundary geometry. A modified algorithm for generation of polycrystalline microstructure of the substrate is designed on the basis of the cellular automata method. The constitutive equations for a steel matrix incorporate an elastic-plastic model for a material subjected to isotropic hardening. The Hall-Petch relation is used to account for the effect of the grain size on the yield stress and strain hardening history. A brittle fracture model for a ceramic coating relying on the Huber criterion is employed. The model allows for crack nucleation in the regions of triaxial tension. The complex inhomogeneous stress and plastic strain patterns are shown to be due to the presence of interfaces of three types: coating-substrate interface, grain boundaries, and pore surfaces.

  17. Titanium powder sintering for preparation of a porous functionally graded material destined for orthopaedic implants.

    PubMed

    Thieme, M; Wieters, K P; Bergner, F; Scharnweber, D; Worch, H; Ndop, J; Kim, T J; Grill, W

    2001-03-01

    This work focuses on basic research into a P/M processed, porous-surfaced and functionally graded material (FGM) destined for a permanent skeletal replacement implant with improved structural compatibility. Based on a perpendicular gradient in porosity the Young's modulus of the material is adapted to the elastic properties of bone in order to prevent stress shielding effects and to provide better long-term performance of the implant-bone system. Using coarse Ti particle fractions the sintering process was accelerated by silicon-assisted liquid-phase sintering (LPS) resulting in a substantial improvement of the neck geometry. A novel evaluation for the strength of the sinter contacts was proposed. The Young's modulus of uniform non-graded stacks ranged from 5 to 80 GPa as determined by ultrasound velocity measurements. Thus, the typical range for cortical bone (10-29 GPa) was covered. The magnitude of the Poisson's ratio proved to be distinctly dependent on the porosity. Specimens with porosity gradients were successfully fabricated and characterized using quantitative description of the microstructural geometry and acoustic microscopy.

  18. Acoustical properties of air-saturated porous material with periodically distributed dead-end pores.

    PubMed

    Leclaire, P; Umnova, O; Dupont, T; Panneton, R

    2015-04-01

    A theoretical and numerical study of the sound propagation in air-saturated porous media with straight main pores bearing lateral cavities (dead-ends) is presented. The lateral cavities are located at "nodes" periodically spaced along each main pore. The effect of periodicity in the distribution of the lateral cavities is studied, and the low frequency limit valid for the closely spaced dead-ends is considered separately. It is shown that the absorption coefficient and transmission loss are influenced by the viscous and thermal losses in the main pores as well as their perforation rate. The presence of long or short dead-ends significantly alters the acoustical properties of the material and can increase significantly the absorption at low frequencies (a few hundred hertz). These depend strongly on the geometry (diameter and length) of the dead-ends, on their number per node, and on the periodicity along the propagation axis. These effects are primarily due to low sound speed in the main pores and to thermal losses in the dead-end pores. The model predictions are compared with experimental results. Possible designs of materials of a few cm thicknesses displaying enhanced low frequency absorption at a few hundred hertz are proposed.

  19. Porous material based on spongy titanium granules: structure, mechanical properties, and osseointegration.

    PubMed

    Rubshtein, A P; Trakhtenberg, I Sh; Makarova, E B; Triphonova, E B; Bliznets, D G; Yakovenkova, L I; Vladimirov, A B

    2014-02-01

    A porous material has been produced by pressing spongy titanium granules with subsequent vacuum sintering. The material with porosity of more than 30% has an open system of interconnecting pores. The Young's modulus and 0.2% proof strength have been measured for the samples having 20-55% porosity. If the porosity is between 30 and 45%, the mechanical properties are determined by irregular shape of pores, which is due to spongy titanium granules. The experiment in vivo was performed on adult rabbits. Before surgery the implants were saturated with adherent autologous bone marrow cells. The implants were introduced into the defects formed in the condyles of tibias and femurs. Investigations of osseointegration of implants having 40% porosity showed that the whole system of pores was filled with mature bone tissue in 16 weeks after surgery. Neogenic bone tissue has an uneven surface formed by lacunas and craters indicative of active resorption and subsequent rearrangement (SEM examination). The bone tissue is pierced by neoformed vessels. Irregular-shaped pores with tortuous walls and numerous lateral channels going through the granules provide necessary conditions for the formation of functional bone tissue in the implant volume and the periimplant region.

  20. A Versatile and Scalable Approach toward Robust Superhydrophobic Porous Materials with Excellent Absorbency and Flame Retardancy

    PubMed Central

    Ruan, Changping; Shen, Mengxia; Ren, Xiaoyan; Ai, Kelong; Lu, Lehui

    2016-01-01

    The frequent oil spillages and the industrial discharge of organic contaminants have not only created severe environmental and ecological crises, but also cause a risk of fire and explosion. These environmental and safety issues emphasize the urgent need for materials that possess superior sorption capability and less flammability and thus can effectively and safely clean up the floating oils and water-insoluble organic compounds. Here we present the successful hydrophobic modification of the flame retardant melamine sponge with a commercial fluorosilicone, by using a facile one-step solvent-free approach and demonstrate that the resultant superhydrophobic sponge not only exhibits extraordinary absorption efficiency (including high capacity, superior selectivity, good recyclability, and simple recycling routes), but also retains excellent flame retardancy and robust stability. In comparison to conventional methods, which usually utilize massive organic solvents, the present approach does not involve any complicated process or sophisticated equipment nor generates any waste liquids, and thus is a more labor-saving, environment-friendly, energy-efficient and cost-effective strategy for the hydrophobic modification. Taking into account the critical role of hydrophobic porous materials, especially in the field of environmental remediation, the approach presented herein would be highly valuable for environmental remediation and industrial applications. PMID:27501762