Structure and properties of hybrid composite materials

NASA Astrophysics Data System (ADS)

Chernyshova, T. A.; Kobeleva, L. I.; Bolotova, L. K.; Katin, I. V.

2013-03-01

The structure and interfacial interaction are studied in the hybrid aluminum-matrix composite materials fabricated by reactive casting combined with mechanical mixing of fillers with a metallic melt. The following types of hardening are considered: hardening by ceramic particles and by the phases formed as isolated inclusions or coatings on ceramic particles during in situ reactions. The hardness and tribological properties of the composite materials as functions of their compositions are discussed.

The interaction of reaction-bonded silicon carbide and inconel 600 with a nickel-based brazing alloy

NASA Astrophysics Data System (ADS)

McDermid, J. R.; Pugh, M. D.; Drew, R. A. L.

1989-09-01

The objective of the present research was to join reaction-bonded silicon carbide (RBSC) to INCONEL 600 (a nickel-based superalloy) for use in advanced heat engine applications using either direct brazing or composite interlayer joining. Direct brazing experiments employed American Welding Society (AWS) BNi-5, a commercial nickel-based brazing alloy, as a filler material; composite interlayers consisted of intimate mixtures of α-SiC and BNi-5 powders. Both methods resulted in the liquid filler metal forming a Ni-Si liquid with the free Si in the RBSC, which, in turn, reacted vigorously with the SiC component of the RBSC to form low melting point constituents in both starting materials and Cr carbides at the metal-ceramic interface. Using solution thermodynamics, it was shown that a Ni-Si liquid of greater than 60 at. pct Ni will decompose a-SiC at the experimental brazing temperature of 1200 ‡C; these calculations are consistent with the experimentally observed composition profiles and reaction morphology within the ceramic. It was concluded that the joining of RBSC to INCONEL 600 using a nickel-based brazing alloy is not feasible due to the inevitability of the filler metal reacting with the ceramic, degrading the high-temperature properties of the base materials.

Ceramic sealants prepared by polymer pyrolysis

NASA Astrophysics Data System (ADS)

Hong, Sung Jin; Kim, Deug Joong; Yoo, Young Sung

2011-02-01

The formation and properties of ceramic seals for SOFC applications prepared by polymer pyrolysis are investigated. A mixture with polymethylsiloxane and fillers are pyrolyzed in a N2 atmosphere. The coefficient of thermal expansion of the ceramic composites was controlled by fillers with a high coefficient of thermal expansion such as AlCo. The morphology of the ceramic composites derived from the mixture with polymethylsiloxane and fillers is composed of fillers embedded in a Si-O-C glass matrix. The thermal expansion behavior and sealing characteristics are measured and discussed

Thread-Mounted Thermocouple

NASA Technical Reports Server (NTRS)

Ward, Stanley W.

1988-01-01

Thread-mounted thermocouple developed to accurately measure temperature of surrounding material. Comprised of threaded rod or bolt drilled along length, dual-hole ceramic insulator rod, thermocouple wire, optional ceramic filler, and epoxy resin. In contact with and takes average temperature of, surrounding material. Fabricated easily in size and metal to suit particular application. Because of simplicity and ability to measure average temperature, widespread use of design foreseen in varity of applications.

Advanced Ceramics from Preceramic Polymers Modified at the Nano-Scale: A Review.

PubMed

Bernardo, Enrico; Fiocco, Laura; Parcianello, Giulio; Storti, Enrico; Colombo, Paolo

2014-03-06

Preceramic polymers, i.e. , polymers that are converted into ceramics upon heat treatment, have been successfully used for almost 40 years to give advanced ceramics, especially belonging to the ternary SiCO and SiCN systems or to the quaternary SiBCN system. One of their main advantages is the possibility of combining the shaping and synthesis of ceramics: components can be shaped at the precursor stage by conventional plastic-forming techniques, such as spinning, blowing, injection molding, warm pressing and resin transfer molding, and then converted into ceramics by treatments typically above 800 °C. The extension of the approach to a wider range of ceramic compositions and applications, both structural and thermo-structural (refractory components, thermal barrier coatings) or functional (bioactive ceramics, luminescent materials), mainly relies on modifications of the polymers at the nano-scale, i.e. , on the introduction of nano-sized fillers and/or chemical additives, leading to nano-structured ceramic components upon thermal conversion. Fillers and additives may react with the main ceramic residue of the polymer, leading to ceramics of significant engineering interest (such as silicates and SiAlONs), or cause the formation of secondary phases, significantly affecting the functionalities of the polymer-derived matrix.

JPRS Report, Science & Technology, USSR: Materials Science

DTIC Science & Technology

1988-03-17

mentally on heat-resistant ceramic coatings, ZrO £ coatings with Y2O3 stabilizer, for determination of the yttrium content which largely contributes to the...with carbon filler in a ceramic matrix was made for the purpose of determining the effect of a hot oxidizing ambient medium on their load capacity... admixture of refractory oxides such as MgO, Si02, C^Oß, N10, SnÜ2 and La203 or excess AI2O3 and Ti02 on the stability of this ceramic material at

Advanced Ceramics from Preceramic Polymers Modified at the Nano-Scale: A Review

PubMed Central

Bernardo, Enrico; Fiocco, Laura; Parcianello, Giulio; Storti, Enrico; Colombo, Paolo

2014-01-01

Preceramic polymers, i.e., polymers that are converted into ceramics upon heat treatment, have been successfully used for almost 40 years to give advanced ceramics, especially belonging to the ternary SiCO and SiCN systems or to the quaternary SiBCN system. One of their main advantages is the possibility of combining the shaping and synthesis of ceramics: components can be shaped at the precursor stage by conventional plastic-forming techniques, such as spinning, blowing, injection molding, warm pressing and resin transfer molding, and then converted into ceramics by treatments typically above 800 °C. The extension of the approach to a wider range of ceramic compositions and applications, both structural and thermo-structural (refractory components, thermal barrier coatings) or functional (bioactive ceramics, luminescent materials), mainly relies on modifications of the polymers at the nano-scale, i.e., on the introduction of nano-sized fillers and/or chemical additives, leading to nano-structured ceramic components upon thermal conversion. Fillers and additives may react with the main ceramic residue of the polymer, leading to ceramics of significant engineering interest (such as silicates and SiAlONs), or cause the formation of secondary phases, significantly affecting the functionalities of the polymer-derived matrix. PMID:28788548

Ceramic materials of low-temperature synthesis for dielectric coating applied by 3D aerosol printing used in nano- and microelectronics, lighting engineering, and spacecraft control devices

NASA Astrophysics Data System (ADS)

Ivanov, A. A.; Tuev, V. I.; Nisan, A. V.; Potapov, G. N.

2016-11-01

A synthesis technique of low-temperature ceramic material based on aluminosilicates of dendrimer morphology capable to contain up to 80 wt % of nitrides and oxides of high-melting compounds as filler has been developed. The synthesis is based on a sol-gel method followed by mechanochemical treatment and ultrasonic dispersing. Dielectric ceramic layers with the layer thickness in the nanometer range and high thermal conductivity have been obtained for the first time by 3D aerosol printing of the synthesized material. The study of the obtained ceramic coating on the metal surface (Al) has proved its use prospects in microelectronics, light engineering, and devices for special purposes.

Study of piezoelectric filler on the properties of PZT-PVDF composites

NASA Astrophysics Data System (ADS)

Matei, Alina; Å¢ucureanu, Vasilica; Vlǎzan, Paulina; Cernica, Ileana; Popescu, Marian; RomaniÅ£an, Cosmin

2017-12-01

The ability to obtain composites with desired functionalities is based on advanced knowledge of the processes synthesis and of the structure of piezoceramic materials, as well the incorporation of different fillers in selected polymer matrix. Polyvinylidene fluoride (PVDF) is a fluorinated polymer with excellent mechanical and electric properties, which it was chosen as matrix due to their applications in a wide range of industrial fields [1-4]. The present paper focuses on the development of composites based on PZT particles as filler obtained by conventional methods and PVDF as polymer matrix. The synthesis of PVDF-PZT composites was obtained by dispersing the ceramic powders in a solution of PVDF in N-methyl-pyrrolidone (NMP) under mechanical mixing and ultrasonication, until a homogenous mixture is obtained. The properties of the piezoceramic fillers before and after embedding into the polymeric matrix were investigated by Fourier transform infrared spectrometry, field emission scanning electron microscopy and X-ray diffraction. In the FTIR spectra, appear a large number of absorption bands which are exclusive of the phases from PVDF matrix confirming the total embedding of PZT filler into matrix. Also, the XRD pattern of the composites has confirmed the presence of crystalline phases of PVDF and the ceramic phase of PZT. The SEM results showed a good distribution of fillers in the matrix.

Characterization of Solid Polymers, Ceramic Gap Filler, and Closed-Cell Polymer Foam Using Low-Load Test Methods

NASA Technical Reports Server (NTRS)

Herring, Helen M.

2008-01-01

Various solid polymers, polymer-based composites, and closed-cell polymer foam are being characterized to determine their mechanical properties, using low-load test methods. The residual mechanical properties of these materials after environmental exposure or extreme usage conditions determines their value in aerospace structural applications. In this experimental study, four separate polymers were evaluated to measure their individual mechanical responses after thermal aging and moisture exposure by dynamic mechanical analysis. A ceramic gap filler, used in the gaps between the tiles on the Space Shuttle, was also tested, using dynamic mechanical analysis to determine material property limits during flight. Closed-cell polymer foam, used for the Space Shuttle External Tank insulation, was tested under low load levels to evaluate how the foam's mechanical properties are affected by various loading and unloading scenarios.

Enhanced lithium battery with polyethylene oxide-based electrolyte containing silane-Al2 O3 ceramic filler.

PubMed

Zewde, Berhanu W; Admassie, Shimelis; Zimmermann, Jutta; Isfort, Christian Schulze; Scrosati, Bruno; Hassoun, Jusef

2013-08-01

A solid polymer electrolyte prepared by using a solvent-free, scalable technique is reported. The membrane is formed by low-energy ball milling followed by hot-pressing of dry powdered polyethylene oxide polymer, LiCF3 SO3 salt, and silane-treated Al2 O3 (Al2 O3 -ST) ceramic filler. The effects of the ceramic fillers on the properties of the ionically conducting solid electrolyte membrane are characterized by using electrochemical impedance spectroscopy, XRD, differential scanning calorimeter, SEM, and galvanostatic cycling in lithium cells with a LiFePO4 cathode. We demonstrate that the membrane containing Al2 O3 -ST ceramic filler performs well in terms of ionic conductivity, thermal properties, and lithium transference number. Furthermore, we show that the lithium cells, which use the new electrolyte together with the LiFePO4 electrode, operate within 65 and 90 °C with high efficiency and long cycle life. Hence, the Al2 O3 -ST ceramic can be efficiently used as a ceramic filler to enhance the performance of solid polymer electrolytes in lithium batteries. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High temperature insulation for ceramic matrix composites

DOEpatents

Merrill, Gary B.; Morrison, Jay Alan

2001-01-01

A ceramic composition is provided to insulate ceramic matrix composites under high temperature, high heat flux environments. The composition comprises a plurality of hollow oxide-based spheres of various dimensions, a phosphate binder, and at least one oxide filler powder, whereby the phosphate binder partially fills gaps between the spheres and the filler powders. The spheres are situated in the phosphate binder and the filler powders such that each sphere is in contact with at least one other sphere. The spheres may be any combination of Mullite spheres, Alumina spheres, or stabilized Zirconia spheres. The filler powder may be any combination of Alumina, Mullite, Ceria, or Hafnia. Preferably, the phosphate binder is Aluminum Ortho-Phosphate. A method of manufacturing the ceramic insulating composition and its application to CMC substrates are also provided.

High temperature insulation for ceramic matrix composites

DOEpatents

Merrill, Gary B.; Morrison, Jay Alan

2000-01-01

A ceramic composition is provided to insulate ceramic matrix composites under high temperature, high heat flux environments. The composite comprises a plurality of hollow oxide-based spheres of varios dimentions, a phosphate binder, and at least one oxide filler powder, whereby the phosphate binder partially fills gaps between the spheres and the filler powders. The spheres are situated in the phosphate binder and the filler powders such that each sphere is in contact with at least one other sphere. The spheres may be any combination of Mullite spheres, Alumina spheres, or stabilized Zirconia spheres. The filler powder may be any combination of Alumina, Mullite, Ceria, or Hafnia. Preferably, the phosphate binder is Aluminum Ortho-Phosphate. A method of manufacturing the ceramic insulating composition and its application to CMC substates are also provided.

High temperature insulation for ceramic matrix composites

DOEpatents

Merrill, Gary B.; Morrison, Jay Alan

2004-01-13

A ceramic composition is provided to insulate ceramic matrix composites under high temperature, high heat flux environments. The composition comprises a plurality of hollow oxide-based spheres of various dimensions, a phosphate binder, and at least one oxide filler powder, whereby the phosphate binder partially fills gaps between the spheres and the filler powders. The spheres are situated in the phosphate binder and the filler powders such that each sphere is in contact with at least one other sphere. The spheres may be any combination of Mullite spheres, Alumina spheres, or stabilized Zirconia spheres. The filler powder may be any combination of Alumina, Mullite, Ceria, or Hafnia. Preferably, the phosphate binder is Aluminum Ortho-Phosphate. A method of manufacturing the ceramic insulating composition and its application to CMC substrates are also provided.

The diametral tensile strength and hydrostability of polymer-ceramic nano-composite (pcnc) material prototypes

NASA Astrophysics Data System (ADS)

Yepez, Johanna

Statement of the problem: There is a weak connection between the filler and the resin matrix of dental composites caused primarily by hydrolysis of silane coupling agent, therefore, jeopardizing the mechanical properties of the dental restorations. Purpose: The purpose of this study was to compare the diametral tensile strength (DTS) of a nano-mechanically bonded polymer ceramic nano composite (pcnc) versus the chemically bonding prototype polymer ceramic nano composite (pcnc) fabricated by using hydrolytically stable interphase. Materials and Methods: Composites were made with 60wt % filler, 38% triethyleneglycol dimethacrylate (TEDGMA), 1% camphorquinone (CQ) and 1% 2-(dimethylamino) ethyl methacrylate (DMAEMA). Tests for DTS were performed using a universal testing machine. The disk-shaped specimens were loaded in compression between two supporting plates at a crosshead speed of 0.5 mm/min until fracture. The samples, measuring 3 mm in height and 6 mm in diameter, were produced in a round stainless steel (SS) mold. A total of 144 samples were created. Groups of 48 samples were made for each of three different fillers. Specimens were soaked in artificial saliva at 37° for four time periods, dry(t=0), 1 day, 7 days, 28 days). At the end of each soaking time DTS tests were performed. Results: There where statistically significant differences in the DTS between the filler groups and the soaking times (p=<0.001) as well as for the pairwise comparison between the different filler group values and between the different soaking times as an individual treatment. Overall, longer soaking times resulted in lower mean DTS values. The DTS of the PCNC for filler #1 decreased to 82.4% of the original value after 1 day of soaking, 67.2% after 7 days and 27.2 % after 28 days. For filler #2 decreased to 54.8% of the original value after 1 day of soaking, 62.3% after 7 days and 61.2% after 28 days. For filler #3 decreased to 71.2% of the original value, 67.3% after 7 days and 51.4% after 28 days (Fig 8). Conclusions: Within the limitation of this study it can be concluded that the use of coupling agent will significantly influence the degradation of the material under wet environment. Clinical Implication: Changes within matrix composition and bonding interphase of resin base composites promise improvements of mechanical properties, decreasing the incidence of clinical failure of posterior composite restorations, hence resulting in a more ideal restorative material for use in posterior segment. The results of this investigation showed that the deficiency of hydrostability in dental composites is a detrimental factor in the mechanical behavior. The silanation of the filler particles have a positive influence on the mechanical properties of dental composites but the hydrolysis of the silane coupling agent can dramatically reduce the average lifetime of dental composites.

High elastic modulus nanopowder reinforced resin composites for dental applications

NASA Astrophysics Data System (ADS)

Wang, Yijun

2007-12-01

Dental restorations account for more than $3 billion dollars a year on the market. Among them, all-ceramic dental crowns draw more and more attention and their popularity has risen because of their superior aesthetics and biocompatibility. However, their relatively high failure rate and labor-intensive fabrication procedure still limit their application. In this thesis, a new family of high elastic modulus nanopowder reinforced resin composites and their mechanical properties are studied. Materials with higher elastic modulus, such as alumina and diamond, are used to replace the routine filler material, silica, in dental resin composites to achieve the desired properties. This class of composites is developed to serve (1) as a high stiffness support to all-ceramic crowns and (2) as a means of joining independently fabricated crown core and veneer layers. Most of the work focuses on nano-sized Al2O3 (average particle size 47 nm) reinforcement in a polymeric matrix with 50:50 Bisphenol A glycidyl methacrylate (Bis-GMA): triethylene glycol dimethacrylate (TEGDMA) monomers. Surfactants, silanizing agents and primers are examined to obtain higher filler levels and enhance the bonding between filler and matrix. Silane agents work best. The elastic modulus of a 57.5 vol% alumina/resin composite is 31.5 GPa compared to current commercial resin composites with elastic modulus <15 GPa. Chemical additives can also effectively raise the hardness to as much as 1.34 GPa. Besides>alumina, diamond/resin composites are studied. An elastic modulus of about 45 GPa is obtained for a 57 vol% diamond/resin composite. Our results indicate that with a generally monodispersed nano-sized high modulus filler, relatively high elastic modulus resin-based composite cements are possible. Time-dependent behavior of our resin composites is also investigated. This is valuable for understanding the behavior of our material and possible fatigue testing in the future. Our results indicate that with effective coupling agents and higher filler loading, viscous flow can be greatly decreased due to the attenuation of mobility of polymer chains. Complementary studies indicate that our resin composites are promising for the proposed applications as a stiff support to all-ceramic crowns.

Interfacial microstructure and shear strength of reactive air brazed oxygen transport membrane ceramic-metal alloy joints

NASA Astrophysics Data System (ADS)

FR, Wahid Muhamad; Yoon, Dang-Hyok; Raju, Kati; Kim, Seyoung; Song, Kwang-sup; Yu, Ji Haeng

2018-01-01

To fabricate a multi-layered structure for maximizing oxygen production, oxygen transport membrane (OTM) ceramics need to be joined or sealed hermetically metal supports for interfacing with the peripheral components of the system. Therefore, in this study, Ag-10 wt% CuO was evaluated as an effective filler material for the reactive air brazing of dense Ce0.9Gd0.1O2-δ-La0.7Sr0.3MnO3±δ (GDC-LSM) OTM ceramics. Thermal decomposition in air and wetting behavior of the braze filler was performed. Reactive air brazing was performed at 1050 °C for 30 min in air to join GDC-LSM with four different commercially available high temperature-resistant metal alloys, such as Crofer 22 APU, Inconel 600, Fecralloy, and AISI 310S. The microstructure and elemental distribution of the ceramic-ceramic and ceramic-metal interfaces were examined from polished cross-sections. The mechanical shear strength at room temperature for the as-brazed and isothermally aged (800 °C for 24 h) joints of all the samples was compared. The results showed that the strength of the ceramic-ceramic joints was decreased marginally by aging; however, in the case of metal-ceramic joints, different decreases in strengths were observed according to the metal alloy used, which was explained based on the formation of different oxide layers at the interfaces.

Alternate nozzle ablative materials program

NASA Technical Reports Server (NTRS)

Kimmel, N. A.

1984-01-01

Four subscale solid rocket motor tests were conducted successfully to evaluate alternate nozzle liner, insulation, and exit cone structural overwrap components for possible application to the Space Shuttle Solid Rocket Motor (SRM) nozzle asasembly. The 10,000 lb propellant motor tests were simulated, as close as practical, the configuration and operational environment of the full scale SRM. Fifteen PAN based and three pitch based materials had no filler in the phenolic resin, four PAN based materials had carbon microballoons in the resin, and the rest of the materials had carbon powder in the resin. Three nozzle insulation materials were evaluated; an aluminum oxide silicon oxide ceramic fiber mat phenolic material with no resin filler and two E-glass fiber mat phenolic materials with no resin filler. It was concluded by MTI/WD (the fabricator and evaluator of the test nozzles) and NASA-MSFC that it was possible to design an alternate material full scale SRM nozzle assembly, which could provide an estimated 360 lb increased payload capability for Space Shuttle launches over that obtainable with the current qualified SRM design.

Radio-physical properties of radiotransparent thermal protection materials in ablation mode

NASA Astrophysics Data System (ADS)

Petrovskiy, V. P.; Pakhomov, E. P.; Politiko, A. A.; Semenenko, V. N.; Chistyaev, V. A.; Balakirev, B. A.; Pervov, A. Yu; Kamalov, A. D.; Sotskova, L. P.

2018-01-01

Experimental method for assessing the impact of the effects of high-temperature ablation processes on the radio physical characteristics of radiotransparent thermal protection materials (RTPM) is developed. Researches for the following RTPM with various structures of glass fillers are completed: press material (radiotransparent thermal protection press material or RTP-200); glass-fiber laminate (glass-fiber radiotransparent organic ceramic matrix or GFR-CM); reinforced composite material of class SiO2-SiO2 (high-temperature radiotransparent ceramic organic matrix or HTRC-OM). The influence of physicochemical transformations in the surface layer of RTPM on transmission and reflection coefficients of electromagnetic waves of RTPM samples and on the value of their complex permittivity is determined.

Thermal behavior of silicone rubber-based ceramizable composites characterized by Fourier transform infrared (FT-IR) spectroscopy and microcalorimetry.

PubMed

Anyszka, Rafał; Bieliński, Dariusz M; Jędrzejczyk, Marcin

2013-12-01

Ceramizable (ceramifiable) silicone rubber-based composites are commonly used for cable insulation. These materials are able to create a protective ceramic layer during fire due to the ceramization process, which occurs at high temperature. When the temperature is increased, the polymer matrix is degraded and filler particles stick together by the fluxing agent, producing a solid, continuous ceramic phase that protects the copper wire from heat and mechanical stress. Despite increasing interest in these materials that has resulted in growing applications in the cable industry, their thermal behavior and ceramization process are still insufficiently described in the literature. In this paper, the thermal behavior of ceramizable silicone rubber-based composites is studied using microcalorimetry and Fourier transform infrared spectroscopy. The analysis of the experimental data made it possible to develop complete information on the mechanism of composite ceramization.

Studies on crosslinked hydroxyapatite-polyethylene composite as a bone-analogue material

NASA Astrophysics Data System (ADS)

Smolko, E.; Romero, G.

2007-08-01

The paper examines the use of different types of polymeric matrix composites in hard-tissue replacement applications. The composite samples were prepared with hydroxyapatite (HA) powder and polyethylenes of different densities. The raw material was first compounded in the extruder and the resulting composite pre-forms were compression molded into desired plates and irradiated with different doses. Modulus of elasticity in tension, tensile strength, tensile fracture strain, elongation at break and gel content were obtained for all composites. Ceramic filler distribution was investigated under scanning electron microscopy (SEM). With HA incorporated in the samples an increase in the values of Young's Modulus, (stiffness) was observed, while elongation at break decreased with the amount of filler, showing increase of brittleness. Tensile strengths at yield and at break decreased with the filler content for LD and MDPE and stayed constant for HDPE.

Silicone Resin Applications for Ceramic Precursors and Composites

PubMed Central

Narisawa, Masaki

2010-01-01

This article reviews the applications of silicone resins as ceramic precursors. The historical background of silicone synthesis chemistry is introduced to explain the production costs and supply availability of various silicones. Thermal degradation processes of silicones are classified in terms of the main chain structure and cyclic oligomer expulsion process, which determine the resulting ceramic yield and the chemical composition. The high temperature decomposition of Si-O-C beyond 1,400 °C in an inert atmosphere and formation of a protective silica layer on material surfaces beyond 1,200 °C in an oxidative atmosphere are discussed from the viewpoints of the wide chemical composition of the Si-O-C materials. Applications of the resins for binding agents, as starting materials for porous ceramics, matrix sources with impregnation, fiber spinning and ceramic adhesions are introduced. The recent development of the process of filler or cross-linking agent additions to resin compounds is also introduced. Such resin compounds are useful for obtaining thick coatings, MEMS parts and bulk ceramics, which are difficult to obtain by pyrolysis of simple organometallic precursors without additives.

New dielectric elastomers with improved properties for energy harvesting and actuation

NASA Astrophysics Data System (ADS)

Stiubianu, George; Bele, Adrian; Tugui, Codrin; Musteata, Valentina

2015-02-01

New materials with large value for dielectric constant were obtained by using siloxane and chemically modified lignin. The modified lignin does not act as a stiffening filler material for the siloxane but acts as bulk filler, preserving the softness and low value of Young's modulus specific for silicones. The measured values for dielectric constant compare positively with the ones for previously tested dielectric elastomers based on siloxane rubber or acrylic rubber loaded with ceramic nanoparticles. The new materials use the well-known silicone chemistry and lignin which is available worldwide in large amounts as a by-product of pulp and paper industry, making its manufacturing affordable. The prepared dielectric elastomers were tested for possible applications for wave, wind and kinetic body motion energy harvesting. Siloxane, lignin, dielectric

Dissimilar Brazed Joints Between Steel and Tungsten Carbide

NASA Astrophysics Data System (ADS)

Voiculescu, I.; Geanta, V.; Binchiciu, H.; Iovanas, D.; Stefanoiu, R.

2017-06-01

Brazing is a joining process used to obtain heterogeneous assemblies between different materials, such as steels, irons, non-ferrous metals, ceramics etc. Some application, like asphalt cutters, require quick solutions to obtain dissimilar joints at acceptable costs, given the very short period of operation of these parts. This paper presents some results obtained during the brazing of dissimilar joints between steel and tungsten carbide by using different types of Ag-Cu system filler materials alloyed with P and Sn. The brazing techniques used were oxygen-gas flame and induction joining. The brazing behaviour was analysed in cross sections by optical and electron microscopy. The metallographic analysis enhanced the adhesion features and the length of penetration in the joining gap. The melting range of the filler materials was measured using thermal analysis.

Copper-silver-titanium filler metal for direct brazing of structural ceramics

DOEpatents

Moorhead, Arthur J.

1987-01-01

A method of joining ceramics and metals to themselves and to one another is described using a brazing filler metal consisting essentially of 35 to 50 atomic percent copper, 15 to 50 atomic percent silver and 10 to 45 atomic percent titanium. This method produces strong joints that can withstand high service temperatures and oxidizing environments.

Thermal properties and dynamic mechanical properties of ceramic fillers filled epoxy composites

NASA Astrophysics Data System (ADS)

Saidina, D. S.; Mariatti, M.; Juliewatty, J.

2015-07-01

This present study is aimed to enhance the thermal and dynamic mechanical properties of ceramic fillers such as Calcium Copper Titanate, CaCu3Ti4O12 (CCTO) and Barium Titanate (BaTiO3) filled epoxy thin film composites. As can be seen from the results, 20 vol% BaTiO3/epoxy thin film composite showed the lowest coefficient of thermal expansion (CTE) value, the highest decomposition temperature (T5 and Tonset) and weight of residue among the composites as the filler has low CTE value, distributed homogeneously throughout the composite and less voids can be seen between epoxy resin and BaTiO3 filler.

Cermet materials

DOEpatents

Kong, Peter C [Idaho Falls, ID

2008-12-23

A self-cleaning porous cermet material, filter and system utilizing the same may be used in filtering particulate and gaseous pollutants from internal combustion engines having intermetallic and ceramic phases. The porous cermet filter may be made from a transition metal aluminide phase and an alumina phase. Filler materials may be added to increase the porosity or tailor the catalytic properties of the cermet material. Additionally, the cermet material may be reinforced with fibers or screens. The porous filter may also be electrically conductive so that a current may be passed therethrough to heat the filter during use. Further, a heating element may be incorporated into the porous cermet filter during manufacture. This heating element can be coated with a ceramic material to electrically insulate the heating element. An external heating element may also be provided to heat the cermet filter during use.

New three-phase polymer-ceramic composite materials for miniaturized microwave antennas

NASA Astrophysics Data System (ADS)

Zhang, Li; Zhang, Jie; Yue, Zhenxing; Li, Longtu

2016-09-01

Unique polymer-ceramic composites for microwave antenna applications were prepared via melt extrusion using high-density polyethylene (HDPE) as the matrix and low-density polyethylene (LDPE) coated BaO-Nd2O3-TiO2 (BNT) ceramic-powders as the filler. By incorporating LDPE into the composites via a coating route, high ceramic-powder volume content (up to 50 vol%) could be achieved. The composites exhibited good microwave dielectric and thermomechanical behaviors. As BNT ceramic content increased from 10 vol% to 50 vol%, the permittivity of the composites increased from 3.45 (9 GHz) to 11.87 (7 GHz), while the dielectric loss remained lower than 0.0016. Microstrip antennas for applications in global positioning systems (GPS) were designed and fabricated from the composites containing 50 vol% BNT ceramics. The results indicate that the composites that have suitable permittivity and low dielectric loss are promising candidates for applications in miniaturized microwave devices, such as antennas.

Joining of ceramics for high performance energy systems. Mid-term progress report, August 1, 1979-March 31, 1980

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

Smeltzer, C E; Metcalfe, A G

The subject program is primarily an exploratory and demonstration study of the use of silicate glass-based adhesives for bonding silicon-base refractory ceramics (SiC, Si/sub 3/N/sub 4/). The projected application is 1250 to 2050/sup 0/F relaxing joint service in high-performance energy conversion systems. The five program tasks and their current status are as follows. Task 1 - Long-Term Joint Stability. Time-temperature-transformation studies of candidate glass adhesives, out to 2000 hours simulated service exposure, are half complete. Task 2 - Environmental and Service Effects on Joint Reliability. Start up delayed due to late delivery of candidate glass fillers and ceramic specimens. Taskmore » 3 - Viscoelastic Damping of Glass Bonded Ceramics. Promising results obtained over approximately the same range of glass viscosity required for joint relaxation function (10/sup 7.5/ to 10/sup 9.5/ poise). Work is 90% complete. Task 4 - Crack Arrest and Crack Diversion by Joints. No work started due to late arrival of materials. Task 5 - Improved Joining and Fabrication Methods. Significant work has been conducted in the area of refractory pre-glazing and the application and bonding of high-density candidate glass fillers (by both hand-artisan and slip-spray techniques). Work is half complete.« less

Copper-silver-titanium-tin filler metal for direct brazing of structural ceramics

DOEpatents

Moorhead, Arthur J.

1988-04-05

A method of joining ceramics and metals to themselves and to one another at about 800.degree. C. is described using a brazing filler metal consisting essentially of 35 to 50 at. % copper, 40 to 50 at. % silver, 1 to 15 at. % titanium, and 2 to 8 at. % tin. This method produces strong joints that can withstand high service temperatures and oxidizing environments.

Wide gap active brazing of ceramic-to-metal-joints for high temperature applications

NASA Astrophysics Data System (ADS)

Bobzin, K.; Zhao, L.; Kopp, N.; Samadian Anavar, S.

2014-03-01

Applications like solid oxide fuel cells and sensors increasingly demand the possibility to braze ceramics to metals with a good resistance to high temperatures and oxidative atmospheres. Commonly used silver based active filler metals cannot fulfill these requirements, if application temperatures higher than 600°C occur. Au and Pd based active fillers are too expensive for many fields of use. As one possible solution nickel based active fillers were developed. Due to the high brazing temperatures and the low ductility of nickel based filler metals, the modification of standard nickel based filler metals were necessary to meet the requirements of above mentioned applications. To reduce thermally induced stresses wide brazing gaps and the addition of Al2O3 and WC particles to the filler metal were applied. In this study, the microstructure of the brazed joints and the thermo-chemical reactions between filler metal, active elements and WC particles were analyzed to understand the mechanism of the so called wide gap active brazing process. With regard to the behavior in typical application oxidation and thermal cycle tests were conducted as well as tensile tests.

Mechanically Strong Aerogels Formed by Templated Growth of Polymer Cross- Linkers on Inorganic Nanoparticles

NASA Technical Reports Server (NTRS)

Leventis, Nicholas; Fabrizio, Eve F.; Johnston, Chris; Meador, Maryann

2004-01-01

In the search for materials with better mechanical, thermal, and electrical properties, it is becoming evident that oftentimes dispersing ceramic nanoparticles in plastics improves performance. Along these lines, chemical bonding (both covalent and noncovalent) between a filler and a polymer improves their compatibility, and thus enhances certain properties of the polymeric matrix above and beyond what is accomplished by simple doping with the filler. When a similarly sized dopant and matrix are used, elementary building blocks may also have certain distinct advantages (e.g., in catalysis). In this context, researchers at the NASA Glenn Research Center reasoned that in the extreme case, where the dopant and the matrix (e.g., a filler and a polymer) are not only sized similarly, but their relative amounts are comparable, the relative roles of the dopant and matrix can be reversed. Then, if the "filler," or a certain form thereof, possesses desirable properties of its own, such properties could be magnified by cross-linking with a polymer. We at Glenn have identified silica as such a filler in its lowest-density form, namely the silica aerogel.

Cermet materials, self-cleaning cermet filters, apparatus and systems employing same

DOEpatents

Kong, Peter C.

2005-07-19

A self-cleaning porous cermet material, filter and system utilizing the same may be used in filtering particulate and gaseous pollutants from internal combustion engines having intermetallic and ceramic phases. The porous cermet filter may be made from a transition metal aluminide phase and an alumina phase. Filler materials may be added to increase the porosity or tailor the catalytic properties of the cermet material. Additionally, the cermet material may be reinforced with fibers or screens. The porous filter may also be electrically conductive so that a current may be passed therethrough to heat the filter during use. Further, a heating element may be incorporated into the porous cermet filter during manufacture. This heating element can be coated with a ceramic material to electrically insulate the heating element. An external heating element may also be provided to heat the cermet filter during use.

Bioactive Wollastonite-Diopside Foams from Preceramic Polymers and Reactive Oxide Fillers

PubMed Central

Fiocco, Laura; Elsayed, Hamada; Ferroni, Letizia; Gardin, Chiara; Zavan, Barbara; Bernardo, Enrico

2015-01-01

Wollastonite (CaSiO3) and diopside (CaMgSi2O6) silicate ceramics have been widely investigated as highly bioactive materials, suitable for bone tissue engineering applications. In the present paper, highly porous glass-ceramic foams, with both wollastonite and diopside as crystal phases, were developed from the thermal treatment of silicone polymers filled with CaO and MgO precursors, in the form of micro-sized particles. The foaming was due to water release, at low temperature, in the polymeric matrix before ceramic conversion, mainly operated by hydrated sodium phosphate, used as a secondary filler. This additive proved to be “multifunctional”, since it additionally favored the phase development, by the formation of a liquid phase upon firing, in turn promoting the ionic interdiffusion. The liquid phase was promoted also by the incorporation of powders of a glass crystallizing itself in wollastonite and diopside, with significant improvements in both structural integrity and crushing strength. The biological characterization of polymer-derived wollastonite-diopside foams, to assess the bioactivity of the samples, was performed by means of a cell culture test. The MTT assay and LDH activity tests gave positive results in terms of cell viability.

Arcjet Tests of Different Gap-Filler Options for the Orion PICA Heatshield

NASA Technical Reports Server (NTRS)

Skokova, Kristina; Ellerby, Donald; Blosser, Max; Venkatapathy, Ethiraj; Bouslog, Stan; Reuther, James

2009-01-01

PICA (Phenolic Infiltrated Carbon Ablator) is one of the candidate thermal protection materials for the Orion vehicle. Because PICA is fabricated in blocks, gaps exist between the blocks, similar to the individual ceramic tiles of the Shuttle thermal protection system. The results of this work focus on arcjet test results of different gap-filler options for PICA, performed as part of the Orion TPS Advanced Development Project. The arcjet tests were performed at NASA Ames Research Center on stagnation models 4 inches in diameter at conditions representative of Orion flight conditions for both Lunar and Low Earth Orbit return. Performance of gap-filler options was evaluated based on the extent of backface temperature change, as compared to PICA without gaps, and on the extent of flow penetration into the gap, evident from the gap opening and widening.

The influence of TiO2 composition in LiBOB electrolyte polymer composite membrane characteristics for lithium ion batteries applications

NASA Astrophysics Data System (ADS)

Lestariningsih, T.; Sabrina, Q.; Wigayati, E. M.

2018-03-01

Characterization of the composite membrane of LiBOB electrolyte polymers made from poly (vinylidene fluoride co-hexafluororopylene) (PVdF-HFP) as the polymer, LiBOB or LiB(C2O4)2 as electrolyte salt and titanium dioxide (TiO2) as ceramic filler of three different concentrations have been done. Sample of membrane was prepared using solution casting technique. Microstructural study by SEM shows non-uniform distribution of pore over the surface of the sample. X-ray structural analysis, impedance spectroscopy, and cyclic voltammetry (CV) studies were carried out. Membrane composite polymer of LiBOB electrolyte without additional ceramic filler with composition of 70% polymer, 30% LiBOB, and 0% TiO2 has the greatest conductivity for forming amorphous phase and is compatible with material membrane composite. Meanwhile, sample with 70% polymer composition, 28% LiBOB and 2% TiO2 shows oxidation reaction at the most perfect discharge despite very slow current speed.

Method of forming a dense, high temperature electronically conductive composite layer on a porous ceramic substrate

DOEpatents

Isenberg, A.O.

1992-04-21

An electrochemical device, containing a solid oxide electrolyte material and an electrically conductive composite layer, has the composite layer attached by: (A) applying a layer of LaCrO[sub 3], YCrO[sub 3] or LaMnO[sub 3] particles, on a portion of a porous ceramic substrate, (B) heating to sinter bond the particles to the substrate, (C) depositing a dense filler structure between the doped particles, (D) shaving off the top of the particles, and (E) applying an electronically conductive layer over the particles as a contact. 7 figs.

Bioglass: A novel biocompatible innovation.

PubMed

Krishnan, Vidya; Lakshmi, T

2013-04-01

Advancement of materials technology has been immense, especially in the past 30 years. Ceramics has not been new to dentistry. Porcelain crowns, silica fillers in composite resins, and glass ionomer cements have already been proved to be successful. Materials used in the replacement of tissues have come a long way from being inert, to compatible, and now regenerative. When hydroxyapatite was believed to be the best biocompatible replacement material, Larry Hench developed a material using silica (glass) as the host material, incorporated with calcium and phosphorous to fuse broken bones. This material mimics bone material and stimulates the regrowth of new bone material. Thus, due to its biocompatibility and osteogenic capacity it came to be known as "bioactive glass-bioglass." It is now encompassed, along with synthetic hydroxyapatite, in the field of biomaterials science known as "bioactive ceramics." The aim of this article is to give a bird's-eye view, of the various uses in dentistry, of this novel, miracle material which can bond, induce osteogenesis, and also regenerate bone.

A Study on Tribological Behavior of Glass-Epoxy Composite Filled with Granite Dust

NASA Astrophysics Data System (ADS)

Ray, Subhrajit; Rout, Arun Ku; KuSahoo, Ashok

2017-08-01

Granite powder is one of the solid wastes generated from stone processing industry used as organic filler replacing the conventional ceramic fillers in polymer matrix composite to increase the mechanical properties. The present work investigates the addition of granite powder on erosion wear properties of epoxy-glass fiber composite. The solid particle erosion wear rates of these hybrid composites are recorded considering various control parameters as impingement angles, erodent sizes and impact velocities following erosion resistance test in an air erosion test device at room temperatures. The test was conducted as per the Taguchi experimental design to minimize the erosion loss of material. The SEM views show the surface resistivity for the granite added specimens. The microscopic study also indicates various methods of material removal, crater wear and other subjective allocation during erosion experiment of the samples.

Mechanical fatigue degradation of ceramics versus resin composites for dental restorations.

PubMed

Belli, Renan; Geinzer, Eva; Muschweck, Anna; Petschelt, Anselm; Lohbauer, Ulrich

2014-04-01

For posterior partial restorations an overlap of indication exists where either ceramic or resin-based composite materials can be successfully applied. The aim of this study was to compare the fatigue resistance of modern dental ceramic materials versus dental resin composites in order to address such conflicts. Bar specimens of five ceramic materials and resin composites were produced according to ISO 4049 and stored for 14 days in distilled water at 37°C. The following ceramic materials were selected for testing: a high-strength zirconium dioxide (e.max ZirCAD, Ivoclar), a machinable lithium disilicate (e.max CAD, Ivoclar), a pressable lithium disilicate ceramic (e-max Press, Ivoclar), a fluorapatite-based glass-ceramic (e.max Ceram, Ivoclar), and a machinable color-graded feldspathic porcelain (Trilux Forte, Vita). The composite materials selected were: an indirect machinable composite (Lava Ultimate, 3M ESPE) and four direct composites with varying filler nature (Clearfil Majesty Posterior, Kuraray; GrandioSO, Voco; Tetric EvoCeram, Ivoclar-Vivadent; and CeramX Duo, Dentsply). Fifteen specimens were tested in water for initial strength (σin) in 4-point bending. Using the same test set-up, the residual flexural fatigue strength (σff) was determined using the staircase approach after 10(4) cycles at 0.5 Hz (n=25). Weibull parameters σ0 and m were calculated for the σin specimens, whereas the σff and strength loss in percentage were obtained from the fatigue experiment. The zirconium oxide ceramic showed the highest σin and σff (768 and 440 MPa, respectively). Although both lithium disilicate ceramics were similar in the static test, the pressable version showed a significantly higher fatigue resistance after cyclic loading. Both the fluorapatite-based and the feldspathic porcelain showed equivalent initial and cyclic fatigue properties. From the composites, the highest filled direct material Clearfil Majesty Posterior showed superior fatigue performance. From all materials, e.max Press and Clearfil Majesty Posterior showed the lowest strength loss (29.6% and 32%, respectively), whereas the other materials lost between 41% and 62% of their flexural strength after cyclic loading. Dental ceramics and resin composite materials show equivalent fatigue strength degradation at loads around 0.5σin values. Apart from the zirconium oxide and the lithium disilicate ceramics, resin composites generally showed better σff after 10,000 cycles than the fluorapatite glass-ceramic and the feldspathic porcelain. Resin composite restorations may be used as an equivalent alternative to glass-rich-ceramic inlays regarding mechanical performance. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Method of forming a dense, high temperature electronically conductive composite layer on a porous ceramic substrate

DOEpatents

Isenberg, Arnold O.

1992-01-01

An electrochemical device, containing a solid oxide electrolyte material and an electrically conductive composite layer, has the composite layer attached by: (A) applying a layer of LaCrO.sub.3, YCrO.sub.3 or LaMnO.sub.3 particles (32), on a portion of a porous ceramic substrate (30), (B) heating to sinter bond the particles to the substrate, (C) depositing a dense filler structure (34) between the doped particles (32), (D) shaving off the top of the particles, and (E) applying an electronically conductive layer over the particles (32) as a contact.

From Artisanal to CAD-CAM Blocks: State of the Art of Indirect Composites.

PubMed

Mainjot, A K; Dupont, N M; Oudkerk, J C; Dewael, T Y; Sadoun, M J

2016-05-01

Indirect composites have been undergoing an impressive evolution over the last few years. Specifically, recent developments in computer-aided design-computer-aided manufacturing (CAD-CAM) blocks have been associated with new polymerization modes, innovative microstructures, and different compositions. All these recent breakthroughs have introduced important gaps among the properties of the different materials. This critical state-of-the-art review analyzes the strengths and weaknesses of the different varieties of CAD-CAM composite materials, especially as compared with direct and artisanal indirect composites. Indeed, new polymerization modes used for CAD-CAM blocks-especially high temperature (HT) and, most of all, high temperature-high pressure (HT-HP)-are shown to significantly increase the degree of conversion in comparison with light-cured composites. Industrial processes also allow for the augmentation of the filler content and for the realization of more homogeneous structures with fewer flaws. In addition, due to their increased degree of conversion and their different monomer composition, some CAD-CAM blocks are more advantageous in terms of toxicity and monomer release. Finally, materials with a polymer-infiltrated ceramic network (PICN) microstructure exhibit higher flexural strength and a more favorable elasticity modulus than materials with a dispersed filler microstructure. Consequently, some high-performance composite CAD-CAM blocks-particularly experimental PICNs-can now rival glass-ceramics, such as lithium-disilicate glass-ceramics, for use as bonded partial restorations and crowns on natural teeth and implants. Being able to be manufactured in very low thicknesses, they offer the possibility of developing innovative minimally invasive treatment strategies, such as "no prep" treatment of worn dentition. Current issues are related to the study of bonding and wear properties of the different varieties of CAD-CAM composites. There is also a crucial need to conduct clinical studies. Last, manufacturers should provide more complete information regarding their product polymerization process, microstructure, and composition, which significantly influence CAD-CAM material properties. © International & American Associations for Dental Research 2016.

Novel dental composites reinforced with zirconia-silica ceramic nanofibers.

PubMed

Guo, Guangqing; Fan, Yuwei; Zhang, Jian-Feng; Hagan, Joseph L; Xu, Xiaoming

2012-04-01

To fabricate and characterize dental composites reinforced with various amounts of zirconia-silica (ZS) or zirconia-yttria-silica (ZYS) ceramic nanofibers. Control composites (70 wt% glass particle filler, no nanofibers) and experimental composites (2.5, 5.0, and 7.5 wt% ZS or ZYS nanofibers replacing glass particle filler) were prepared by blending 29 wt% dental resin monomers, 70 wt% filler, and 1.0 wt% initiator, and polymerized by either heat or dental curing light. Flexural strength (FS), flexural modulus (FM), energy at break (EAB), and fracture toughness (FT) were tested after the specimens were stored in 37°C deionized water for 24h, 3 months, or 6 months. Degree of conversion (DC) of monomers in composites was measured using Fourier transformed near-infrared (FT-NIR) spectroscopy. Fractured surfaces were observed by field-emission scanning electron microscope (FE-SEM). The data were analyzed using ANOVA with Tukey's Honestly Significant Differences test used for post hoc analysis. Reinforcement of dental composites with ZS or ZYS nanofibers (2.5% or 5.0%) can significantly increase the FS, FM and EAB of dental composites over the control. Further increase the content of ZS nanofiber (7.5%), however, decreases these properties (although they are still higher than those of the control). Addition of nanofibers did not decrease the long-term mechanical properties of these composites. All ZS reinforced composites (containing 2.5%, 5.0% and 7.5% ZS nanofibers) exhibit significantly higher fracture toughness than the control. The DC of the composites decreases with ZS nanofiber content. Incorporation of ceramic nanofibers in dental composites can significantly improve their mechanical properties and fracture toughness and thus may extend their service life. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Development of a New Ferrous Aluminosilicate Refractory Material for Investment Casting of Aluminum Alloys

NASA Astrophysics Data System (ADS)

Yuan, Chen; Jones, Sam; Blackburn, Stuart

2012-12-01

Investment casting is a time-consuming, labour intensive process, which produces complex, high value-added components for a variety of specialised industries. Current environmental and economic pressures have resulted in a need for the industry to improve current casting quality, reduce manufacturing costs and explore new markets for the process. Alumino-silicate based refractories are commonly used as both filler and stucco materials for ceramic shell production. A new ceramic material, norite, is now being produced based on ferrous aluminosilicate chemistry, having many potential advantages when used for the production of shell molds for casting aluminum alloy. This paper details the results of a direct comparison made between the properties of a ceramic shell system produced with norite refractories and a typical standard refractory shell system commonly used in casting industry. A range of mechanical and physical properties of the systems was measured, and a full-scale industrial casting trial was also carried out. The unique properties of the norite shell system make it a promising alternative for casting aluminum based alloys in the investment foundry.

High Ionic Conductivity of Composite Solid Polymer Electrolyte via In Situ Synthesis of Monodispersed SiO2 Nanospheres in Poly(ethylene oxide).

PubMed

Lin, Dingchang; Liu, Wei; Liu, Yayuan; Lee, Hye Ryoung; Hsu, Po-Chun; Liu, Kai; Cui, Yi

2016-01-13

High ionic conductivity solid polymer electrolyte (SPE) has long been desired for the next generation high energy and safe rechargeable lithium batteries. Among all of the SPEs, composite polymer electrolyte (CPE) with ceramic fillers has garnered great interest due to the enhancement of ionic conductivity. However, the high degree of polymer crystallinity, agglomeration of ceramic fillers, and weak polymer-ceramic interaction limit the further improvement of ionic conductivity. Different from the existing methods of blending preformed ceramic particles with polymers, here we introduce an in situ synthesis of ceramic filler particles in polymer electrolyte. Much stronger chemical/mechanical interactions between monodispersed 12 nm diameter SiO2 nanospheres and poly(ethylene oxide) (PEO) chains were produced by in situ hydrolysis, which significantly suppresses the crystallization of PEO and thus facilitates polymer segmental motion for ionic conduction. In addition, an improved degree of LiClO4 dissociation can also be achieved. All of these lead to good ionic conductivity (1.2 × 10(-3) S cm(-1) at 60 °C, 4.4 × 10(-5) S cm(-1) at 30 °C). At the same time, largely extended electrochemical stability window up to 5.5 V can be observed. We further demonstrated all-solid-state lithium batteries showing excellent rate capability as well as good cycling performance.

Development of a high temperature ceramic-to-metal seal for Air Force Weapons Laboratory Laser

NASA Astrophysics Data System (ADS)

Honnell, R. E.; Stoddard, S. D.

1987-03-01

Procedures were developed for fabricating vacuum tight metal-to-ceramic ring seals between Inconel 625 and MgO-3 wt % Y2O3 tubes metallized with a calcia-alumina-silica glass (CaO-29 wt % Al2O3-35 wt % SiO2) containing 50 vol % molybdenum filler. Palniro No. 1 (Au-25 wt % Pd-25 wt % Ni) was found to be the most reliable braze for joining Inconel to metallized MgO-3 wt % Y2O3 bodies. The reliabilities of the processing procedures and the material systems were demonstrated. A prototype electrical feedthrough was fabricated for 1173 K operation in air or vacuum.

Methods of producing cermet materials and methods of utilizing same

DOEpatents

Kong, Peter C [Idaho Falls, ID

2008-12-30

Methods of fabricating cermet materials and methods of utilizing the same such as in filtering particulate and gaseous pollutants from internal combustion engines having intermetallic and ceramic phases. The cermet material may be made from a transition metal aluminide phase and an alumina phase. The mixture may be pressed to form a green compact body and then heated in a nitrogen-containing atmosphere so as to melt aluminum particles and form the cermet. Filler materials may be added to increase the porosity or tailor the catalytic properties of the cermet material. Additionally, the cermet material may be reinforced with fibers or screens. The cermet material may also be formed so as to pass an electrical current therethrough to heat the material during use.

Methods of fabricating cermet materials and methods of utilizing same

DOEpatents

Kong, Peter C.

2006-04-04

Methods of fabricating cermet materials and methods of utilizing the same such as in filtering particulate and gaseous pollutants from internal combustion engines having intermetallic and ceramic phases. The cermet material may be made from a transition metal aluminide phase and an aluminia phase. The mixture may be pressed to form a green compact body and then heated in a nitrogen-containing atmosphere so as to melt aluminum particles and form the cermet. Filler materials may be added to increase the porosity or tailor the catalytic properties of the cermet material. Additionally, the cermet material may be reinforced with fibers or screens. The cermet material may also be formed so as to pass an electrical current therethrough to heat the material during use.

In-flight investigation of shuttle tile pressure orifice installations

NASA Technical Reports Server (NTRS)

Moes, Timothy R.; Meyer, Robert R., Jr.

1990-01-01

To determine shuttle orbiter wing loads during ascent, wing load instrumentation was added to Columbia (OV-102). This instrumentation included strain gages and pressure orifices on the wing. The loads derived from wing pressure measurements taken during STS 61-C did not agree with those derived from strain gage measurements or with the loads predicted from the aerodynamic database. Anomalies in the surface immediately surrounding the pressure orifices in the thermal protection system (TPS) tiles were one possible cause of errors in the loads derived from wing pressure measurements. These surface anomalies were caused by a ceramic filler material which was installed around the pressure tubing. The filler material allowed slight movement of the TPS tile and pressure tube as the airframe flexed and bent under aerodynamic loads during ascent and descent. Postflight inspection revealed that this filler material had protruded from or receeded beneath the surface, causing the orifice to lose its flushness. Flight tests were conducted at NASA Ames Research Center Dryden Flight Research Facility to determine the effects of any anomaly in surface flushness of the orifice installation on the measured pressures at Mach numbers between 0.6 and 1.4. An F-104 aircraft with a flight test fixture mounted beneath the fuselage was used for these flights. Surface flushness anomalies typical of those on the orbiter after flight (STA 61-C) were tested. Also, cases with excessive protrusion and recession of the filler material were tested. This report shows that the anomalies in STS 61-C orifice installations adversely affected the pressure measurements. But the magnitude of the affect was not great enough to account for the discrepancies with the strain gage measurements and the aerodynamic predictions.

Low Temperature Reactivities of Ultra-High Temperature Ceramics (Hf-X System)

DTIC Science & Technology

2006-03-01

as interacting fillers with the preceramic polymer formulations. In situ formation of the SiC phase was also evaluated as a practical approach in...silicon (reaction-bonded SiC ), which was introduced either as a powder mixed in the original composite formulation or as a subsequent infiltrant that...and their aerospace and turbine applications has led to a renewal of activities to fabricate MB 2/ SiC composites as the materials of choice, because

Application for oxytetracycline wastewater pretreatment by Fenton iron mud based cathodic-anodic-electrolysis ceramic granular fillers.

PubMed

Zhang, Feilong; Yue, Qinyan; Gao, Yuan; Gao, Baoyu; Xu, Xing; Ren, Zhongfei; Jin, Yang

2017-09-01

In this study, Fenton iron mud applied as main raw material of cathodic-anodic-electrolysis ceramic granular fillers (ICMF) in a continuous reactor, which were used to pretreat oxytetracycline (OTC) wastewater. The ICMF was characterized by Scanning Electron Microscope and Energy Dispersive Spectrometer analysis. The effects of pH value, hydraulic retention time, OTC concentrations and aeration on removal efficiency of total organic carbon (TOC) and OTC were studied. The degradation byproducts of OTC were analyzed by UV-2450, High Performance Liquid Chromatography and Liquid Chromatography-mass Spectrometry. The SEM images showed that the surface ICMF was porous. This system had a higher stability, and good removal efficiency of TOC of 80.5% and OTC of 98.5% under the optimal conditions, which were influent pH of 3, HRT of 4 h, and anaerobic condition. After running for 60 d, the removal efficiency of TOC was stable and the ICMF did not become hardened. The reactor was back washed by acid solution (pH: 1) in 20 d approximately. This paper provides useful information for approaching in wastewater pretreatment and recycling the Fenton iron mud. Copyright © 2017 Elsevier Ltd. All rights reserved.

Integration Science and Technology of Silicon-Based Ceramics and Composites:Technical Challenges and Opportunities

NASA Technical Reports Server (NTRS)

Singh, M.

2013-01-01

Ceramic integration technologies enable hierarchical design and manufacturing of intricate ceramic and composite parts starting with geometrically simpler units that are subsequently joined to themselves and/or to metals to create components with progressively higher levels of complexity and functionality. However, for the development of robust and reliable integrated systems with optimum performance for high temperature applications, detailed understanding of various thermochemical and thermomechanical factors is critical. Different technical approaches are required for the integration of ceramic to ceramic and ceramic to metal systems. Active metal brazing, in particular, is a simple and cost-effective method to integrate ceramic to metallic components. Active braze alloys usually contain a reactive filler metal (e.g., Ti, Cr, V, Hf etc) that promotes wettability and spreading by inducing chemical reactions with the ceramics and composites. In this presentation, various examples of brazing of silicon nitride to themselves and to metallic systems are presented. Other examples of joining of ceramic composites (C/SiC and SiC/SiC) using ceramic interlayers and the resulting microstructures are also presented. Thermomechanical characterization of joints is presented for both types of systems. In addition, various challenges and opportunities in design, fabrication, and testing of integrated similar (ceramic-ceramic) and dissimilar (ceramic-metal) material systems will be discussed. Potential opportunities and need for the development of innovative design philosophies, approaches, and integrated system testing under simulated application conditions will also be presented.

Experimental investigation of a molten salt thermocline storage tank

NASA Astrophysics Data System (ADS)

Yang, Xiaoping; Yang, Xiaoxi; Qin, Frank G. F.; Jiang, Runhua

2016-07-01

Thermal energy storage is considered as an important subsystem for solar thermal power stations. Investigations into thermocline storage tanks have mainly focused on numerical simulations because conducting high-temperature experiments is difficult. In this paper, an experimental study of the heat transfer characteristics of a molten salt thermocline storage tank was conducted by using high-temperature molten salt as the heat transfer fluid and ceramic particle as the filler material. This experimental study can verify the effectiveness of numerical simulation results and provide reference for engineering design. Temperature distribution and thermal storage capacity during the charging process were obtained. A temperature gradient was observed during the charging process. The temperature change tendency showed that thermocline thickness increased continuously with charging time. The slope of the thermal storage capacity decreased gradually with the increase in time. The low-cost filler material can replace the expensive molten salt to achieve thermal storage purposes and help to maintain the ideal gravity flow or piston flow of molten salt fluid.

Recycling of the product of thermal inertization of cement-asbestos for various industrial applications

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

Gualtieri, Alessandro F., E-mail: alessandro.gualtieri@unimore.it; Giacobbe, Carlotta; Sardisco, Lorenza

Recycling of secondary raw materials is a priority of waste handling in the countries of the European community. A potentially important secondary raw material is the product of the thermal transformation of cement-asbestos, produced by prolonged annealing at 1200-1300 {sup o}C. The product is chemically comparable to a Mg-rich clinker. Previous work has assured the reliability of the transformation process. The current challenge is to find potential applications as secondary raw material. Recycling of thermally treated asbestos-containing material (named KRY.AS) in traditional ceramics has already been studied with successful results. The results presented here are the outcome of a longmore » termed project started in 2005 and devoted to the recycling of this secondary raw materials in various industrial applications. KRY.AS can be added in medium-high percentages (10-40 wt%) to commercial mixtures for the production of clay bricks, rock-wool glasses for insulation as well as Ca-based frits and glass-ceramics for the production of ceramic tiles. The secondary raw material was also used for the synthesis of two ceramic pigments; a green uvarovite-based pigment [Ca{sub 3}Cr{sub 2}(SiO{sub 4}){sub 3}] and a pink malayaite-based pigment [Ca(Sn,Cr)SiO{sub 5}]. The latter is especially interesting as a substitute for cadmium-based pigments. This work also shows that KRY.AS can replace standard fillers in polypropylene plastics without altering the properties of the final product. For each application, a description and relevant results are presented and discussed.« less

Comparison and simulation of salt-ceramic composites for use in high temperature concentrated solar power

NASA Astrophysics Data System (ADS)

Fossile, Lauren Michelle

Due to the inherently intermittent nature of solar energy caused by cloud cover among other sources, thermal storage systems are needed to make solar energy more consistent. This same technology could be used to prolong the daily number of useful hours of solar energy power plants. Salt-ceramic materials are a relatively new prospect for heat storage, but have been researched mostly with magnesium oxide and several different carbonate salts. Salt ceramics are a phase change material where the salt changes phase inside the ceramic structure allowing for the system to use the sensible heat of both materials and the latent heat of the salt to store thermal energy. Capillary forces within the ceramic structure hold in the salt when the salt melts. The focus here is on the possibility of creating a low-cost salt-ceramic storage material for high temperature solar energy applications. A theoretical analysis of the resulting materials is performed. While most of the existing salt ceramics have been made from magnesium oxide, aluminum oxide is more readily available from various companies in the area. Magnesium oxide is often considered a custom ceramic, so it is more expensive. A cost and material property comparison has been completed between these two materials to determine which is better suited for solar storage. Many of the existing salt-ceramics use carbonate salts, but nitrate salts are commonly used in graphite/salt composites. Therefore, a cost and theoretical performance comparison is between these materials also. For comparisons' sake, zirconia and graphite have also been analyzed as the filler in the composite. Each combination of salt and ceramic or graphite has been analyzed. In order to make the use of salt-ceramics more cost-effective and available to Nevada's energy providers, research has been done into which ceramics have high availability in Nevada, low cost, and the best material properties for this application. The thermal properties and cost of these materials have been compared to the price that Nevada's energy utilities are willing to pay per unit of stored energy, which was approximated through a survey conducted by the National Science Foundation (NSF) - Experimental Project to Stimulate Competitive Research (EPSCoR) at the University of Nevada, Las Vegas. The surveys were completed on Nevadan energy purveyors concerning climate change attitudes, but included questions regarding the usefulness and cost of solar storage. The cost per unit of energy has also been calculated and whether the utilities would be willing to pay for each combination will be determined using information obtained from the surveys mentioned above. This information will dictate which combination will be best for use in the state of Nevada at solar energy power plants.

Oxidation resistant filler metals for direct brazing of structural ceramics

DOEpatents

Moorhead, Arthur J.

1986-01-01

A method of joining ceramics and metals to themselves and to one another is described using essentially pure trinickel aluminide and trinickel aluminide containing small amounts of carbon. This method produces strong joints that can withstand high service temperatures and oxidizing environments.

Characterization of Inorganic Filler Content, Mechanical Properties, and Light Transmission of Bulk-fill Resin Composites.

PubMed

Fronza, B M; Ayres, Apa; Pacheco, R R; Rueggeberg, F A; Dias, Cts; Giannini, M

The aims of this study were to characterize inorganic content (IC), light transmission (LT), biaxial flexural strength (BFS), and flexural modulus (FM) of one conventional (layered) and four bulk-fill composites at different depths. Bulk-fill composites tested were Surefil SDR flow (SDR), Filtek Bulk Fill (FBF), Tetric EvoCeram Bulk Fill (TEC), and EverX Posterior (EXP). Herculite Classic (HER) was used as a control. Energy dispersive x-ray analysis and scanning electron microscopy were used to characterize filler particle composition and morphology. The LT through different composite thicknesses (1, 2, 3, and 4 mm) was measured using a laboratory-grade spectral radiometer system (n=5). For the BFS and FM tests, sets of eight stacked composite discs (0.5-mm thick) were prepared simulating bulk filling of a 4-mm-thick increment (n=8). SDR demonstrated larger, irregular particles than those observed in TEC or HER. Filler particles in FBF were spherical, while those in EXP were composed of fiberglass strands. The LT decreased with increased composite thickness for all materials. Bulk-fill composites allowed higher LT than the HER. Furthermore, HER proved to be the unique material, having lower BFS values at deeper regions. SDR, FBF, and TEC bulk-fill composites presented reduced FM with increasing composite depth. The bulk-fill composites investigated exhibited higher LT, independent of different filler content and characteristics. Although an increase in composite thickness reduced LT, the BFS of bulk-fill composites at deeper layers was not compromised.

Conductivity and Thermal Studies on Plasticized Nano-Composite Solid Polymer Electrolyte, Peo: Ec: LiTf: Al2O3

NASA Astrophysics Data System (ADS)

Pitawala, H. M. J. C.; Dissanayake, M. A. K. L.; Seneviratne, V. A.

2006-06-01

Poly (ethylene oxide)-(PEO)-based composite polymer electrolytes are of great interest for solid-state-electrochemical devices. This paper presents the results of a preliminary study on electrical conductivity and thermal behavior (DSC) of composite polymer electrolytes (CPEs) containing PEO: LiCF3SO3 complexed with plasticizer (EC) and incorporating nano-sized particles of the ceramic filler Al2O3. Ionic conductivity enhancement in these electrolytes has been obtained by optimizing the combined effect of the plasticizer and the ceramic filler. Nano-composite, plasticized polymer electrolyte films (400-600μm) were prepared by common solvent casting method. It was revealed that the presence of the Al2O3 filler in PEO: LiTf polymer electrolyte significantly enhanced the ionic conductivity in the temperature range of interest, giving the maximum conductivity for (PEO)9LiTf+15 wt.% Al2O3 CPE [σRT (max)=2×10-5 S cm-1]. It was also observed that the addition of plasticizer (EC) to this electrolyte up to a concentration of 50 wt. % EC, showed a further conductivity enhancement [σRT (max) = 1.5×10-4 S cm-1]. It is suggested that the conductivity is enhanced mainly by two mechanisms. The plasticizer (EC) would directly contribute by reducing the crystallinity and increasing the amorphous phase content of the polymer electrolytes. The ceramic filler (Al2O3) would contribute to conductivity enhancement by creating additional sites to migrating ionic species through transient bonding with O/OH groups in the filler surface. The decrease of Tg values of plasticized CPE systems seen in the DSC thermograms points towards the improved segmental flexibility of polymer chains, increasing the mobility of conducting ions.

Low-Temperature Reactivities of Ultra-High Temperature Ceramics (Hf-X System)

DTIC Science & Technology

2005-12-01

as interacting fillers with the preceramic polymer formulations. In situ formation of the SiC phase was also evaluated as a practical approach in...led to a renewal of activities to fabricate MB2/ SiC composites as the materials of choice, because of their high thermal and oxidation resistance...HfB2/ SiC composite microstructures (and also HfC, ZrB2, and ZrC composites ) under pressureless conditions. These can be employed in reactive and

Quaternary Polymer Electrolytes Containing an Ionic Liquid and a Ceramic Filler.

PubMed

Sharova, Varvara; Kim, Guk-Tae; Giffin, Guinevere A; Lex-Balducci, Alexandra; Passerini, Stefano

2016-07-01

In this work, the individual and combined effects of an ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide and ceramic filler silicon dioxide on the thermal and electrochemical properties of poly(ethylene oxide) electrolytes have been investigated. The electrolyte containing both components has the lowest glass transition (-60 °C) and melting temperatures (27 °C), the highest conductivity at any investigated temperature, and the highest limiting current density (at 40 °C). This solid polymer electrolyte also exhibits the best long-term cycling performance in Li/LiFePO4 cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Flame Retardant Effect of Nano Fillers on Polydimethylsiloxane Composites.

PubMed

Jagdale, Pravin; Salimpour, Samera; Islam, Md Hujjatul; Cuttica, Fabio; Hernandez, Francisco C Robles; Tagliaferro, Alberto; Frache, Alberto

2018-02-01

Polydimethylsiloxane has exceptional fire retardancy characteristics, which make it a popular polymer in flame retardancy applications. Flame retardancy of polydimethylsiloxane with different nano fillers was studied. Polydimethylsiloxane composite fire property varies because of the shape, size, density, and chemical nature of nano fillers. In house made carbon and bismuth oxide nano fillers were used in polydimethylsiloxane composite. Carbon from biochar (carbonised bamboo) and a carbon by-product (carbon soot) were selected. For comparative study of nano fillers, standard commercial multiwall carbon nano tubes (functionalised, graphitised and pristine) as nano fillers were selected. Nano fillers in polydimethylsiloxane positively affects their fire retardant properties such as total smoke release, peak heat release rate, and time to ignition. Charring and surface ceramization are the main reasons for such improvement. Nano fillers in polydimethylsiloxane may affect the thermal mobility of polymer chains, which can directly affect the time to ignition. The study concludes that the addition of pristine multiwall carbon nano tubes and bismuth oxide nano particles as filler in polydimethylsiloxane composite improves the fire retardant property.

HDPE/HA composites obtained in solution: Effect of the gamma radiation

NASA Astrophysics Data System (ADS)

Carmen, Albano; Arquímedes, Karam; Rosestela, Perera; Gema, González; Nohemy, Domínguez; Jeanette, González; Yanixia, Sánchez

2006-06-01

Radiation is employed to sterilize composite materials used in the biomedical field. Due to the changes induced by radiation onto polymeric materials, it is important to study variations in their melt flow index (MFI), as well as in their mechanical and thermal properties. In this work, those previous parameters were determined in composites obtained via solution of a high-density polyethylene (HDPE) in decalin, with different amounts of hydroxyapatite (HA), varying from 10 to 30 parts per hundred, after being exposed to gamma radiation at absorbed doses between 25 and 100 kGy. After the irradiation, the MFI of HDPE dissolved in decalin and precipitated afterwards and without filler increased from 6 to 24 g/10 min at the highest absorbed doses. This behavior was also observed in composites with 10 pph of HA, being the increase less pronounced, specifically in the range between 50 and 100 kGy. Composites with 20 and 30 pph of HA showed a maximum MFI value at 50 kGy, which decreased at higher doses. This implies that the filler begin to exert an influence because it does not melt at the test temperature and consequently, it does not flow. It was observed that Young's modulus increased with HA addition due to rigidity of the ceramic filler. Radiation did not significantly affect this tensile property. On the other hand, the tensile strength did not show significant variations at the different doses but the filler content did affect this property improving it. Finally, elongation at break showed a drastic decrease with filler addition. When the thermal behavior was studied it was noticed that crystallization and melting temperatures remained unchanged. Instead, crystallinity degree slightly increased in the composites, and a little decrease was obtained when they were irradiated.

Antibacterial properties of Ag-exchanged Philippine natural zeolite-chitosan composites

NASA Astrophysics Data System (ADS)

Taaca, Kathrina Lois M.; Olegario, Eleanor M.; Vasquez, Magdaleno R.

2017-12-01

Zeolites are microporous minerals composed of silicon, aluminum and oxygen. These aluminosilicates consist of tetrahedral units which produce open framework structures to generate a system of pores and cavities of molecular dimensions. Zeolites are naturally abundant and can be mined in most parts of the world. In this study, natural zeolites (NaZ) which are locally-sourced here in the Philippines were investigated to determine its properties. An ion-exchange process was utilized, using the zeolite to silver (Ag) solution ratio of 1:20 (w/v), to incorporate Ag into the zeolite framework. Characterizations such as XRD, AAS, and Agar diffusion assay were used to evaluate the properties of the synthesized Ag-exchanged zeolites (AgZ). X-ray diffraction revealed that both NaZ and AgZ have peaks mostly corresponding to the clinoptilolite structure, with some trace peaks of the mordenite and quartz. Absorption spectroscopy revealed that the ion exchange process added about 0.61188g of silver into the zeolite structure. This Ag content was seen to be enough to make the AgZ sample exhibit an antibacterial effect where clearing zones against E. coli and S. aureus were observed in the agar diffusion assay, respectively. The AgZ sample was also tested as ceramic filler to a polymer matrix-chitosan. The diffusion assay revealed presence of antibacterial activity to the polymer composite with AgZ fillers. These results indicate that the Philippine natural zeolite, incorporated with metals such as Ag, can be used as an antibacterial agent and can be developed as a ceramic filler to improve the antibacterial property of composite materials for biomedical application.

Characterization and modeling of an advanced flexible thermal protection material for space applications

NASA Technical Reports Server (NTRS)

Clayton, Joseph P.; Tinker, Michael L.

1991-01-01

This paper describes experimental and analytical characterization of a new flexible thermal protection material known as Tailorable Advanced Blanket Insulation (TABI). This material utilizes a three-dimensional ceramic fabric core structure and an insulation filler. TABI is the leading candidate for use in deployable aeroassisted vehicle designs. Such designs require extensive structural modeling, and the most significant in-plane material properties necessary for model development are measured and analytically verified in this study. Unique test methods are developed for damping measurements. Mathematical models are developed for verification of the experimental modulus and damping data, and finally, transverse properties are described in terms of the inplane properties through use of a 12-dof finite difference model of a simple TABI configuration.

Ceramic-like open-celled geopolymer foam as a porous substrate for water treatment catalyst

NASA Astrophysics Data System (ADS)

Kovářík, T.; Křenek, T.; Pola, M.; Rieger, D.; Kadlec, J.; Franče, P.

2017-02-01

This paper presents results from experimental study on microstructural and mechanical properties of geopolymer-based foam filters. The process for making porous ceramic-like geopolymer body was experimentally established, consists of (a) geopolymer paste synthesis, (b) ceramic filler incorporation, (c) coating of open-celled polyurethane foam with geopolymer mixture, (d) rapid setting procedure, (e) thermal treatment. Geopolymer paste was based on potassium silicate solution n(SiO2)/n(K2O)=1.6 and powder mixture of calcined kaolin and precipitated silica. Various types of ceramic granular filler (alumina, calcined schistous clay and cordierite) were tested in relation to aggregate gradation design and particle size distribution. The small amplitude oscillatory rheometry in strain controlled regime 0.01% with angular frequency 10 rad/s was applied for determination of rheology behavior of prepared mixtures. Thermal treatment conditions were applied in the temperature range 1100 - 1300 °C. The developed porous ceramic-like foam effectively served as a substrate for highly active nanoparticles of selected Fe+2 spinels. Such new-type of nanocomposite was tested as a heterogeneous catalyst for technological process of advanced oxidative degradation of resistive antibiotics occurring in waste waters.

Innovative Self-Healing Seals for Solid Oxide Fuel Cells (SOFC)

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

Raj Singh

Solid oxide fuel cell (SOFC) technology is critical to several national initiatives. Solid State Energy Conversion Alliance (SECA) addresses the technology needs through its comprehensive programs on SOFC. A reliable and cost-effective seal that works at high temperatures is essential to the long-term performance of the SOFC for 40,000 hours at 800°C. Consequently, seals remain an area of highest priority for the SECA program and its industry teams. An innovative concept based on self-healing glasses was advanced and successfully demonstrated through seal tests for 3000 hours and 300 thermal cycles to minimize internal stresses under both steady state and thermalmore » transients for making reliable seals for the SECA program. The self-healing concept requires glasses with low viscosity at the SOFC operating temperature of 800°C but this requirement may lead to excessive flow of the glass in areas forming the seal. To address this challenge, a modification to glass properties by addition of particulate fillers is pursued in the project. The underlying idea is that a non-reactive ceramic particulate filler is expected to form glass-ceramic composite and increase the seal viscosity thereby increasing the creep resistance of the glass-composite seals under load. The objectives of the program are to select appropriate filler materials for making glass-composite, fabricate glass-composites, measure thermal expansion behaviors, and determine stability of the glass-composites in air and fuel environments of a SOFC. Self-healing glass-YSZ composites are further developed and tested over a longer time periods under conditions typical of the SOFCs to validate the long-term stability up to 2000 hours. The new concepts of glass-composite seals, developed and nurtured in this program, are expected to be cost-effective as these are based on conventional processing approaches and use of the inexpensive materials.« less

Use of high temperature insulation for ceramic matrix composites in gas turbines

DOEpatents

Morrison, Jay Alan; Merrill, Gary Brian; Ludeman, Evan McNeil; Lane, Jay Edgar

2001-01-01

A ceramic composition for insulating components, made of ceramic matrix composites, of gas turbines is provided. The composition comprises a plurality of hollow oxide-based spheres of various dimensions, a phosphate binder, and at least one oxide filler powder, whereby the phosphate binder partially fills gaps between the spheres and the filler powders. The spheres are situated in the phosphate binder and the filler powders such that each sphere is in contact with at least one other sphere and the arrangement of spheres is such that the composition is dimensionally stable and chemically stable at a temperature of approximately 1600.degree. C. A stationary vane of a gas turbine comprising the composition of the present invention bonded to the outer surface of the vane is provided. A combustor comprising the composition bonded to the inner surface of the combustor is provided. A transition duct comprising the insulating coating bonded to the inner surface of the transition is provided. Because of abradable properties of the composition, a gas turbine blade tip seal comprising the composition also is provided. The composition is bonded to the inside surface of a shroud so that a blade tip carves grooves in the composition so as to create a customized seal for the turbine blade tip.

Light transmittance and micro-mechanical properties of bulk fill vs. conventional resin based composites.

PubMed

Bucuta, Stefan; Ilie, Nicoleta

2014-11-01

The aim of this study was to quantify the blue light that passes through different incremental thicknesses of bulk fill in comparison to conventional resin-based composites (RBCs) and to relate it to the induced mechanical properties. Seven bulk fill, five nanohybrid and two flowable RBCs were analysed. Specimens (n = 5) of three incremental thicknesses (2, 4 and 6 mm) were cured from the top for 20 s, while at the bottom, a spectrometer monitored in real time the transmitted irradiance. Micro-mechanical properties (Vickers hardness, HV, and indentation modulus, E) were measured at the top and bottom after 24 h of storage in distilled water at 37 °C. Electron microscope images were taken for assessing the filler distribution and size. Bulk fill RBCs (except SonicFill) were more translucent than conventional RBCs. Low-viscosity bulk fill materials showed the lowest mechanical properties. HV depends highly on the following parameters: material (ηp (2) = 0.952), incremental thickness (0.826), filler volume (0.747), filler weight (0.746) and transmitted irradiance (0.491). The bottom-to-top HV ratio (HVbt) was higher than 80 % in all materials in 2- and 4-mm increments (except for Premise), whereas in 6-mm increments, this is valid only in four bulk fill materials (Venus Bulk Fill, SDR, x-tra fil, Tetric EvoCeram Bulk Fill). The depth of cure is dependent on the RBC's translucency. Low-viscosity bulk fill RBCs have lower mechanical properties than all other types of analysed materials. All bulk fill RBCs (except SonicFill) are more translucent for blue light than conventional RBCs. Although bulk fill RBCs are generally more translucent, the practitioner has to follow the manufacturer's recommendations on curing technique and maximum incremental thickness.

An overview of development and status of fiber-reinforced composites as dental and medical biomaterials

PubMed Central

Vallittu, Pekka K.

2018-01-01

Abstract Fibr-reinforced composites (FRC) have been used successfully for decades in many fields of science and engineering applications. Benefits of FRCs relate to physical properties of FRCs and versatile production methods, which can be utilized. Conventional hand lamination of prefabricated FRC prepregs is utilized still most commonly in fabrication of dental FRC devices but CAD-CAM systems are to be come for use in certain production steps of dental constructions and medical FRC implants. Although metals, ceramics and particulate filler resin composites have successfully been used as dental and medical biomaterials for decades, devices made out of these materials do not meet all clinical requirements. Only little attention has been paid to FRCs as dental materials and majority of the research in dental field has been focusing on particulate filler resin composites and in medical biomaterial research to biodegradable polymers. This is paradoxical because FRCs can potentially resolve many of the problems related to traditional isotropic dental and medical materials. This overview reviews the rationale and status of using biostable glass FRC in applications from restorative and prosthetic dentistry to cranial surgery. The overview highlights also the critical material based factors and clinical requirement for the succesfull use of FRCs in dental reconstructions. PMID:29707613

An overview of development and status of fiber-reinforced composites as dental and medical biomaterials.

PubMed

Vallittu, Pekka K

2018-01-01

Fibr-reinforced composites (FRC) have been used successfully for decades in many fields of science and engineering applications. Benefits of FRCs relate to physical properties of FRCs and versatile production methods, which can be utilized. Conventional hand lamination of prefabricated FRC prepregs is utilized still most commonly in fabrication of dental FRC devices but CAD-CAM systems are to be come for use in certain production steps of dental constructions and medical FRC implants. Although metals, ceramics and particulate filler resin composites have successfully been used as dental and medical biomaterials for decades, devices made out of these materials do not meet all clinical requirements. Only little attention has been paid to FRCs as dental materials and majority of the research in dental field has been focusing on particulate filler resin composites and in medical biomaterial research to biodegradable polymers. This is paradoxical because FRCs can potentially resolve many of the problems related to traditional isotropic dental and medical materials. This overview reviews the rationale and status of using biostable glass FRC in applications from restorative and prosthetic dentistry to cranial surgery. The overview highlights also the critical material based factors and clinical requirement for the succesfull use of FRCs in dental reconstructions.

Modeling & processing of ceramic and polymer precursor ceramic matrix composite materials

NASA Astrophysics Data System (ADS)

Wang, Xiaolin

Synthesis and processing of novel materials with various advanced approaches have attracted much attention of engineers and scientists for the past thirty years. Many advanced materials display a number of exceptional properties and can be produced with different novel processing techniques. For example, AlN is a promising candidate for electronic, optical and opto-electronic applications due to its high thermal conductivity, high electrical resistivity, high acoustic wave velocity and large band gap. Large bulk AlN crystal can be produced by sublimation of AlN powder. Novel nonostructured multicomponent refractory metal-based ceramics (carbides, borides and nitrides) show a lot of exceptional mechanical, thermal and chemical properties, and can be easily produced by pyrolysis of suitable preceramic precursors mixed with metal particles. The objective of this work is to study sublimation and synthesis of AlN powder, and synthesis of SiC-based metal ceramics. For AlN sublimation crystal growth, we will focus on modeling the processes in the powder source that affect significantly the sublimation growth as a whole. To understand the powder porosity evolution and vapor transport during powder sublimation, the interplay between vapor transport and powder sublimation will be studied. A physics-based computational model will be developed considering powder sublimation and porosity evolution. Based on the proposed model, the effect of a central hole in the powder on the sublimation rate is studied and the result is compared to the case of powder without a hole. The effect of hole size on the sublimation rate will be studied. The effects of initial porosity, particle size and driving force on the sublimation rate are also studied. Moreover, the optimal growth condition for large diameter crystal quality and high growth rate will be determined. For synthesis of SiC-based metal ceramics, we will focus on developing a multi-scale process model to describe the dynamic behavior of filler particle reaction, microstructure evolution, at the microscale as well as transient fluid flow, heat transfer, and species transport at the macroscale. The model comprises of (i) a microscale model and (ii) a macroscale transport model, and aims to provide optimal conditions for the fabrication process of the ceramics. The porous media macroscale model for SiC-based metal-ceramic materials processing will be developed to understand the thermal polymer pyrolysis, chemical reaction of active fillers and transport phenomena in the porous media. The macroscale model will include heat and mass transfer, curing, pyrolysis, chemical reaction and crystallization in a mixture of preceramic polymers and submicron/nano-sized metal particles of uranium, zirconium, niobium, or hafnium. The effects of heating rate, sample size, size and volume ratio of the metal particles on the reaction rate and product uniformity will be studied. The microscale model will be developed for modeling the synthesis of SiC matrix and metal particles. The macroscale model provides thermal boundary conditions to the microscale model. The microscale model applies to repetitive units in the porous structure and describes mass transport, composition changes and motion of metal particles. The unit-cell is the representation unit of the source material, and it consists of several metal particles, SiC matrix and other components produced from the synthesis process. The reactions between different components, the microstructure evolution of the product will be considered. The effects of heating rate and metal particle size on species uniformity and microstructure are investigated.

Approaches to polymer-derived CMC matrices

NASA Technical Reports Server (NTRS)

Hurwitz, Frances I.

1992-01-01

The use of polymeric precursors to ceramics permits the fabrication of large, complex-shaped ceramic matrix composites (CMC's) at temperatures which do not degrade the fiber. Processing equipment and techniques readily available in the resin matrix composite industry can be adapted for CMC fabrication using this approach. Criteria which influence the choice of candidate precursor polymers, the use of fillers, and the role of fiber architecture and ply layup are discussed. Three polymer systems, polycarbosilanes, polysilazanes, and polysilsesquioxanes, are compared as candidate ceramic matrix precursors.

Electrostatic Assembly Preparation of High-Toughness Zirconium Diboride-Based Ceramic Composites with Enhanced Thermal Shock Resistance Performance.

PubMed

Zhang, Baoxi; Zhang, Xinghong; Hong, Changqing; Qiu, Yunfeng; Zhang, Jia; Han, Jiecai; Hu, PingAn

2016-05-11

The central problem of using ceramic as a structural material is its brittleness, which associated with rigid covalent or ionic bonds. Whiskers or fibers of strong ceramics such as silicon carbide (SiC) or silicon nitride (Si3N4) are widely embedded in a ceramic matrix to improve the strength and toughness. The incorporation of these insulating fillers can impede the thermal flow in ceramic matrix, thus decrease its thermal shock resistance that is required in some practical applications. Here we demonstrate that the toughness and thermal shock resistance of zirconium diboride (ZrB2)/SiC composites can be improved simultaneously by introducing graphene into composites via electrostatic assembly and subsequent sintering treatment. The incorporated graphene creates weak interfaces of grain boundaries (GBs) and optimal thermal conductance paths inside composites. In comparison to pristine ZrB2-SiC composites, the toughness of (2.0%) ZrB2-SiC/graphene composites exhibited a 61% increasing (from 4.3 to 6.93 MPa·m(1/2)) after spark plasma sintering (SPS); the retained strength after thermal shock increased as high as 74.8% at 400 °C and 304.4% at 500 °C. Present work presents an important guideline for producing high-toughness ceramic-based composites with enhanced thermal shock properties.

Light irradiance through novel CAD-CAM block materials and degree of conversion of composite cements.

PubMed

Lise, Diogo Pedrollo; Van Ende, Annelies; De Munck, Jan; Yoshihara, Kumiko; Nagaoka, Noriyuki; Cardoso Vieira, Luiz Clovis; Van Meerbeek, Bart

2018-02-01

To assess light irradiance (LI) delivered by two light-curing units (LCU's) and to measure the degree of conversion (DC) of three composite cements, when cured through different thicknesses of two novel CAD-CAM block materials. 100-μm-thick films of a dual-curable composite cement (G-CEM LinkAce, GC), a light-curable flowable resin-based composite (RBC) (G-ænial Universal Flo, GC) and a micro-hybrid RBC (G-ænial Posterior, GC) were investigated as luting agents. Two 'polymer-ceramic' CAD-CAM blocks (Cerasmart, GC; Enamic, Vita Zahnfabrik) were sectioned in slabs with different thicknesses (1, 3 and 5mm). LI at the bottom of the specimens was measured using a calibrated spectrometer, while being light-cured through the CAD-CAM block slabs for 40s with a low- (±500mW/cm 2 ) or high- (±1,600mW/cm 2 ) irradiance LCU (n=5). After light-curing, micro-Raman spectra of the composite films were acquired to determine DC at 5min, 10min, 1h and 24h. LI data were statistically analyzed by Kruskal-Wallis followed by post-hoc comparisons, while a linear mixed-effect model was applied for the DC analysis. In addition, the CAD-CAM blocks ultrastructure was characterized upon argon-ion slicing using scanning transmission electron microscopy (STEM). Finally, light transmission (LT) through each CAD-CAM block material was assessed using a spectrophotometer. Curing-light attenuation and DC were significantly influenced by thickness and type of the overlying material. LCU only had a significant effect on DC of the micro-hybrid RBC. DC significantly increased over time for all composite cements. CAD-CAM block structural analysis revealed a relatively small and homogenous filler configuration (mean filler size of 0.2-0.5μm) for Cerasmart, while Enamic contained ceramic grains varying in shape and size (1-10μm), which were interconnected by the polymer-based network. LT was much higher at a wavelength range of 300-800nm for Cerasmart than for Enamic. Light-curable composite cements can be cured through a restoration up to 2.7-mm thickness, depending on the kind of CAD-CAM material. A high-irradiance LCU only has a limited effect on the maximum thickness of the polymer-ceramic CAD-CAM material that can be cured through. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

STS-114 Mission Support - Photograph EVA Tile Repair Procedures for Contingency

NASA Image and Video Library

2005-07-31

JSC2005-E-30915 (31 July 2005) --- NASA astronaut Joe Tanner (foreground) joins other astronauts and engineers at the Johnson Space Center to practice techniques to eliminate or trim protruding gap fillers that Astronauts Noguchi and Robinson will use during their spacewalk. The ceramic coated-fabric gap fillers are used to protect against hot gas from seeping into gaps between the Shuttle’s protective tiles. Photo credit: NASA/James Blair

STS-114 Mission Support - Photograph EVA Tile Repair Procedures for Contingency

NASA Image and Video Library

2005-07-31

JSC2005-E-30917 (31 July 2005) --- Astronaut Joe Tanner joins other astronauts and engineers at the Johnson Space Center to practice techniques to eliminate or trim protruding gap fillers that Astronauts Noguchi and Robinson will use during their spacewalk. The ceramic coated-fabric gap fillers are used to protect against hot gas from seeping into gaps between the Shuttle’s protective tiles. Photo Credit: NASA/James Blair

Post-irradiation hardness development, chemical softening, and thermal stability of bulk-fill and conventional resin-composites.

PubMed

Alshali, Ruwaida Z; Salim, Nesreen A; Satterthwaite, Julian D; Silikas, Nick

2015-02-01

To measure bottom/top hardness ratio of bulk-fill and conventional resin-composite materials, and to assess hardness changes after dry and ethanol storage. Filler content and kinetics of thermal decomposition were also tested using thermogravimetric analysis (TGA). Six bulk-fill (SureFil SDR, Venus bulk fill, X-tra base, Filtek bulk fill flowable, Sonic fill, and Tetric EvoCeram bulk-fill) and eight conventional resin-composite materials (Grandioso flow, Venus Diamond flow, X-flow, Filtek Supreme Ultra Flowable, Grandioso, Venus Diamond, TPH Spectrum, and Filtek Z250) were tested (n=5). Initial and 24h (post-cure dry storage) top and bottom microhardness values were measured. Microhardness was re-measured after the samples were stored in 75% ethanol/water solution. Thermal decomposition and filler content were assessed by TGA. Results were analysed using one-way ANOVA and paired sample t-test (α=0.05). All materials showed significant increase of microhardness after 24h of dry storage which ranged from 100.1% to 9.1%. Bottom/top microhardness ratio >0.9 was exhibited by all materials. All materials showed significant decrease of microhardness after 24h of storage in 75% ethanol/water which ranged from 14.5% to 74.2%. The extent of post-irradiation hardness development was positively correlated to the extent of ethanol softening (R(2)=0.89, p<0.001). Initial thermal decomposition temperature assessed by TGA was variable and was correlated to ethanol softening. Bulk-fill resin-composites exhibit comparable bottom/top hardness ratio to conventional materials at recommended manufacturer thickness. Hardness was affected to a variable extent by storage with variable inorganic filler content and initial thermal decomposition shown by TGA. The manufacturer recommended depth of cure of bulk-fill resin-composites can be reached based on the microhardness method. Characterization of the primary polymer network of a resin-composite material should be considered when evaluating its stability in the aqueous oral environment. Copyright © 2014 Elsevier Ltd. All rights reserved.

An anion-immobilized composite electrolyte for dendrite-free lithium metal anodes

PubMed Central

Zhao, Chen-Zi; Zhang, Xue-Qiang; Cheng, Xin-Bing; Zhang, Rui; Xu, Rui; Chen, Peng-Yu; Peng, Hong-Jie; Huang, Jia-Qi

2017-01-01

Lithium metal is strongly regarded as a promising electrode material in next-generation rechargeable batteries due to its extremely high theoretical specific capacity and lowest reduction potential. However, the safety issue and short lifespan induced by uncontrolled dendrite growth have hindered the practical applications of lithium metal anodes. Hence, we propose a flexible anion-immobilized ceramic–polymer composite electrolyte to inhibit lithium dendrites and construct safe batteries. Anions in the composite electrolyte are tethered by a polymer matrix and ceramic fillers, inducing a uniform distribution of space charges and lithium ions that contributes to a dendrite-free lithium deposition. The dissociation of anions and lithium ions also helps to reduce the polymer crystallinity, rendering stable and fast transportation of lithium ions. Ceramic fillers in the electrolyte extend the electrochemically stable window to as wide as 5.5 V and provide a barrier to short circuiting for realizing safe batteries at elevated temperature. The anion-immobilized electrolyte can be applied in all–solid-state batteries and exhibits a small polarization of 15 mV. Cooperated with LiFePO4 and LiNi0.5Co0.2Mn0.3O2 cathodes, the all–solid-state lithium metal batteries render excellent specific capacities of above 150 mAh⋅g−1 and well withstand mechanical bending. These results reveal a promising opportunity for safe and flexible next-generation lithium metal batteries. PMID:28973945

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

Cao, J., E-mail: cao_jian@hit.edu.cn; State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001; Song, X.G., E-mail: song_xiaoguohit@yahoo.com.cn

Reliable brazing of ZrO{sub 2} ceramic and Ti–6Al–4V alloy was achieved using NiCrSiB amorphous filler foil. The interfacial microstructure of ZrO{sub 2}/Ti–6Al–4V joints was characterized by scanning electron microscope, energy dispersive spectrometer and micro-focused X-ray diffractometer. The effects of brazing temperature on the interfacial microstructure and joining properties of brazed joints were investigated in detail. Active Ti of Ti–6Al–4V alloy dissolved into molten filler metal and reacted with ZrO{sub 2} ceramic to form a continuous TiO reaction layer, which played an important role in brazing. Various reaction phases including Ti{sub 2}Ni, Ti{sub 5}Si{sub 3} and β-Ti were formed in brazedmore » joints. With an increasing of brazing temperature, the TiO layer thickened gradually while the Ti{sub 2}Ni amount reduced. Shear test indicated that brazed joints tend to fracture at the interface between ZrO{sub 2} ceramic and brazing seam or Ti{sub 2}Ni intermetallic layer. The maximum average shear strength reached 284.6 MPa when brazed at 1025 °C for 10 min. - Graphical Abstract: Interfacial microstructure of ZrO{sub 2}/TC4 joint brazed using NiCrSiB amorphous filler foil was: ZrO{sub 2}/TiO/Ti{sub 2}Ni + β-Ti + Ti{sub 5}Si{sub 3}/β-Ti/Widmanstätten structure/TC4. - Highlights: • Brazing of ZrO{sub 2} ceramic and Ti-6Al-4V alloy was achieved. • Interfacial microstructure was TiO/Ti{sub 2}Ni + β + Ti{sub 5}Si{sub 3}/β/Widmanstätten structure. • The formation of TiO produced the darkening effect of ZrO{sub 2} ceramic. • The highest joining strength of 284.6MPa was obtained.« less

Development and tests on OREX vehicle thermal structure system

NASA Astrophysics Data System (ADS)

Yoshinaka, Toshinari; Morino, Yoshiki

1992-08-01

An overview of the thermal system structure development and their tests for Orbital Re-entry Experiment (OREX) vehicle, being developed as a part of H-2 Orbiting Plane (HOPE) development, is presented. The results of study on the OREX vehicle thermal structure system and concept of the system study are shown. The results of HOPE thermal structure system research were reflected to OREX in employing polyacrylonitrile tissues with conversion coating for the nose cap, Carbon-Thermal Protection System (TPS), and ceramic tile TPS for the structure. Test plans were established for material characteristics and design verifications, and flight validation for C/C (Carbon/Carbon Composite) nose cap and TPS, and gap filler, arc wind tunnel, heat insulation, and adhesion quality verification tests. Environment resistance of the C/C nose cone, C/C TPS, and ceramic tile TPS were verified and prospects of their manufacturing were obtained.

Effects of magnetic field treatment on dielectric properties of CCTO@Ni/PVDF composite with low concentration of ceramic fillers

NASA Astrophysics Data System (ADS)

Chi, Q. G.; Gao, L.; Wang, X.; Chen, Y.; Dong, J. F.; Cui, Y.; Lei, Q. Q.

2015-11-01

Using melt mixing, we produced a ceramic/polymer composite with a matrix of polyvinylidene fluoride (PVDF) and a filler of 5 vol.% Ni-deposited CaCu3Ti4O12 core-shell ceramic particles (CCTO@Ni), and studied its prominent dielectric characteristics for the first. Its phase composition and morphology were analyzed by X-ray diffraction and scanning electron microscopy, respectively. After treating the composite films with various durations of a magnetic field treatment, we compared their dielectric properties. We found that the CCTO@Ni ceramic had a typical urchin-like core-shell structure, and that different durations of the magnetic field treatment produced different distributions of ceramic particles in the PVDF matrix. The dielectric permittivity of the untreated CCTO@Ni/PVDF composite was 20% higher than that of neat PVDF, and it had a low loss tangent. However, only the composite treated for 30 min in the magnetic field had an ultra-high dielectric permittivity of 1.41 × 104 at 10 Hz, three orders of magnitude higher than the untreated composite, which declined dramatically with increasing frequency, accompanied by an insulating-conducting phase transition and an increase in loss tangent. Our results demonstrate that changes in the dielectric properties of PVDF composites with magnetic field treatment are closely related to the percolation effect and interfacial polarization.

Putty-like bone fillers based on CaP ceramics or Biosilicate® combined with carboxymethylcellulose: Characterization, optimization, and evaluation.

PubMed

Gabbai-Armelin, Paulo R; Renno, Ana Cm; Crovace, Murilo C; Magri, Angela Mp; Zanotto, Edgar D; Peitl, Oscar; Leeuwenburgh, Sander Cg; Jansen, John A; van den Beucken, Jeroen Jjp

2017-08-01

Calcium phosphates and bioactive glass ceramics have been considered promising biomaterials for use in surgeries. However, their moldability should be further enhanced. We here thereby report the handling, physicochemical features, and morphological characteristics of formulations consisting of carboxymethylcellulose-glycerol and hydroxyapatite-tricalcium phosphate or Biosilicate® particles. We hypothesized that combining either material with carboxymethylcellulose-glycerol would improve handling properties, retaining their bioactivity. In addition to scanning electron microscopy, cohesion, mineralization, pH, and viscoelastic properties of the novel formulations, cell culture experiments were performed to evaluate the cytotoxicity and cell proliferation. Putty-like formulations were obtained with improved cohesion and moldability. Remarkably, mineralization in simulated body fluid of hydroxyapatite-tricalcium phosphate/carboxymethylcellulose-glycerol formulations was enhanced compared to pure hydroxyapatite-tricalcium phosphate. Cell experiments showed that all formulations were noncytotoxic and that HA-TCP60 and BGC50 extracts led to an increased cell proliferation. We conclude that combining carboxymethylcellulose-glycerol with either hydroxyapatite-tricalcium phosphate or Biosilicate® allows for the generation of moldable putties, improves handling properties, and retains the ceramic bioactivity.

Enhanced dielectric performance of three phase percolative composites based on thermoplastic-ceramic composites and surface modified carbon nanotube

NASA Astrophysics Data System (ADS)

Yang, Yang; Sun, Haoliang; Zhu, Benpeng; Wang, Ziyu; Wei, Jianhong; Xiong, Rui; Shi, Jing; Liu, Zhengyou; Lei, Qingquan

2015-01-01

Three-phase composites were prepared by embedding CaCu3Ti4O12(CCTO) nanoparticles and Multiwalled Carbon Nanotube (MWNT) into polyimide (PI) matrix via in-situ polymerization. The dependences of electric and dielectric properties of the resultant composites on volume fractions of filler and frequency were investigated. The dielectric permittivity of PI/CCTO-surface modified MWNT (MWNT-S) composite reached as high as 252 at 100 Hz at 0.1 vol. % filler (MWNT-S), which is about 63 times higher than that of pure PI. Also the dielectric loss is only 0.02 at 100 Hz. The results are in good agreement with the percolation theory. It is shown that embedding high aspect ratio MWNT-S in PI/CCTO composites is an effective means to enhance the dielectric permittivity and reduce the percolation threshold. The dielectric properties of the composites will meet the practical requirements for the application in high dielectric constant capacitors and high energy density materials.

Mechanisms Underlying Ionic Mobilities in Nanocomposite Polymer Electrolytes

NASA Astrophysics Data System (ADS)

Ganesan, Venkat; Hanson, Benjamin; Pryamitsyn, Victor

2014-03-01

Recently, a number of experiments have demonstrated that addition of ceramics with nanoscale dimensions can lead to substantial improvements in the low temperature conductivity of the polymeric materials. However, the origin of such behaviors, and more generally, the manner by which nanoscale fillers impact the ion mobilities remain unresolved. In this communication, we report the results of atomistic molecular dynamics simulations which used multibody polarizable force-fields to study lithium ion diffusivities in an amorphous poly(ethylene-oxide) (PEO) melt containing well-dispersed TiO2 nanoparticles. We observed that the lithium ion diffusivities decrease with increased particle loading. Our analysis suggests that the ion mobilities are correlated to the nanoparticle-induced changes in the polymer segmental dynamics. Interestingly, the changes in polymer segmental dynamics were seen to be related to the nanoparticle's influence on the polymer conformational features. Overall, our results indicate that addition of nanoparticle fillers modify polymer conformations and the polymer segmental dynamics, and thereby influence the ion mobilities of polymer electrolytes.

Tailoring chain length and cross-link density in dielectric elastomer toward enhanced actuation strain

NASA Astrophysics Data System (ADS)

Zhang, Quan-Ping; Liu, Jun-Hua; Liu, Hai-Dong; Jia, Fei; Zhou, Yuan-Lin; Zheng, Jian

2017-10-01

Adding ceramic or conductive fillers into polymers for increasing permittivity is a direct and effective approach to enhance the actuation strain of dielectric elastomer actuators (DEAs). Unfortunately, the major dielectric loss caused by weak interfaces potentially harms the electro-mechanical stability and lifetime of DEAs. Here, we construct a desired macromolecular network with a long chain length and low cross-link density to reduce the elastic modulus of silicone elastomers. Selecting a high molecular weight of polymethylvinylsiloxane and a low dose of the cross-linker leads the soft but tough networks with rich entanglements, poor cross-links, and a low amount of defects. Then, a ductile material with low elastic modulus but high elongation at break is obtained. It accounts for much more excellent actuation strain of Hl in comparison to that of the other silicone elastomers. Importantly, without other fillers, the ultralow dielectric loss, conductivity, and firm networks possibly promote the electro-mechanical stability and lifetime for the DEA application.

Dielectric properties of polyhedral oligomeric silsesquioxane (POSS)-based nanocomposites at 77k

NASA Astrophysics Data System (ADS)

Pan, Ming-Jen; Gorzkowski, Edward; McAllister, Kelly

2011-10-01

The goal of this study is to develop dielectric nanocomposites for high energy density applications at liquid nitrogen temperature by utilizing a unique nano-material polyhedral oligomeric silsesquioxanes (POSS). A POSS molecule is consisted of a silica cage core with 8 silicon and 12 oxygen atoms and organic functional groups attached to the corners of the cage. In this study, we utilize POSS for the fabrication of nanocomposites both as a silica nanoparticle filler to enhance the breakdown strength and as a surfactant for effective dispersion of high permittivity ceramic nanoparticles in a polymer matrix. The matrix materials selected for the study are polyvinylidene fluoride (PVDF) and poly(methyl methacrylate) (PMMA). The ceramic nanoparticles are barium strontium titanate (BST 50/50) and strontium titanate. The dielectric properties of the solution-cast nanocomposites films were correlated to the composition and processing conditions. We determined that the addition of POSS did not provide enhanced dielectric performance in PVDF- and PMMA-based materials at either room temperature or 77K. In addition, we found that the dielectric breakdown strength of PMMA is lower at 77K than at room temperature, contradicting literature data.

ZnO core spike particles and nano-networks and their wide range of applications

NASA Astrophysics Data System (ADS)

Wille, S.; Mishra, Y. K.; Gedamu, D.; Kaps, S.; Jin, X.; Koschine, T.; Bathnagar, A.; Adelung, R.

2011-05-01

In our approach we are producing a polymer composite material with ZnO core spike particles as concave fillers. The core spike particles are synthesized by a high throughput method. Using PDMS (Polydimethylsiloxane) as a matrix material the core spike particles achieve not only a high mechanical reinforcement but also influence other material properties in a very interesting way, making such a composite very interesting for a wide range of applications. In a very similar synthesis route a nanoscopic ZnO-network is produced. As a ceramic this network can withstand high temperatures like 1300 K. In addition this material is quite elastic. To find a material with these two properties is a really difficult task, as polymers tend to decompose already at lower temperatures and metals melt. Especially under ambient conditions, often oxygen creates a problem for metals at these temperatures. If this material is at the same time a semiconductor, it has a high potential as a multifunctional material. Ceramic or classical semiconductors like III-V or IIVI type are high temperature stable, but typically brittle. This is different on the nanoscale. Even semiconductor wires like silicon with a very small diameter do not easily built up enough stress that leads to a failure while being bent, because in a first order approximation the maximum stress of a fiber scales with its diameter.

Weldability Characteristics of Sintered Hot-Forged AISI 4135 Steel Produced through P/M Route by Using Pulsed Current Gas Tungsten Arc Welding

NASA Astrophysics Data System (ADS)

Joseph, Joby; Muthukumaran, S.; Pandey, K. S.

2016-01-01

Present investigation is an attempt to study the weldability characteristics of sintered hot-forged plates of AISI 4135 steel produced through powder metallurgy (P/M) route using matching filler materials of ER80S B2. Compacts of homogeneously blended elemental powders corresponding to the above steel were prepared on a universal testing machine (UTM) by taking pre-weighed powder blend with a suitable die, punch and bottom insert assembly. Indigenously developed ceramic coating was applied on the entire surface of the compacts in order to protect them from oxidation during sintering. Sintered preforms were hot forged to flat, approximately rectangular plates, welded by pulsed current gas tungsten arc welding (PCGTAW) processes with aforementioned filler materials. Microstructural, tensile and hardness evaluations revealed that PCGTAW process with low heat input could produce weldments of good quality with almost nil defects. It was established that PCGTAW joints possess improved tensile properties compared to the base metal and it was mainly attributed to lower heat input, resulting in finer fusion zone grains and higher fusion zone hardness. Thus, the present investigation opens a new and demanding field in research.

A model problem concerning ionic transport in microstructured solid electrolytes

NASA Astrophysics Data System (ADS)

Curto Sillamoni, Ignacio J.; Idiart, Martín I.

2015-11-01

We consider ionic transport by diffusion and migration through microstructured solid electrolytes. The assumed constitutive relations for the constituent phases follow from convex energy and dissipation potentials which guarantee thermodynamic consistency. The effective response is determined by homogenizing the relevant field equations via the notion ofmulti-scale convergence. The resulting homogenized response involves several effective tensors, but they all require the solution of just one standard conductivity problem over the representative volume element. A multi-scale model for semicrystalline polymer electrolytes with spherulitic morphologies is derived by applying the theory to a specific class of two-dimensional microgeometries for which the effective response can be computed exactly. An enriched model accounting for a random dispersion of filler particles with interphases is also derived. In both cases, explicit expressions for the effective material parameters are provided. The models are used to explore the effect of crystallinity and filler content on the overall response. Predictions support recent experimental observations on doped poly-ethylene-oxide systems which suggest that the anisotropic crystalline phase can actually support faster ion transport than the amorphous phase along certain directions dictated by the morphology of the polymeric chains. Predictions also support the viewpoint that ceramic fillers improve ionic conductivity and cation transport number via interphasial effects.

Polymerization shrinkage and hygroscopic expansion of contemporary posterior resin-based filling materials--a comparative study.

PubMed

Rüttermann, Stefan; Krüger, Sören; Raab, Wolfgang H-M; Janda, Ralf

2007-10-01

To investigate the polymerization shrinkage and hygroscopic expansion of contemporary posterior resin-based filling materials. The densities of SureFil (SU), CeramXMono (CM), Clearfil AP-X (CF), Solitaire 2 (SO), TetricEvoCeram (TE), and Filtek P60 (FT) were measured using the Archimedes' principle prior to and 15min after curing for 20, 40 and 60s and after 1h, 24h, 7 d, and 30 d storage at 37 degrees C in water. Volumetric changes (DeltaV) in percent after polymerization and after each storage period in water were calculated from the changes of densities. Water sorption and solubility were determined after 30 d for all specimens and their curing times. Two-way ANOVA was calculated for shrinkage and repeated measures ANOVA was calculated for hygroscopic expansion (p<0.05). DeltaV depended on filler load but not on curing time (SU approximately -2.0%, CM approximately -2.6%, CF approximately -2.1%, SO approximately -3.3%, TE approximately -1.7%, FT approximately -1.8%). Hygroscopic expansion depended on water sorption and solubility. Except for SU, all materials showed DeltaV approximately +1% after water storage. Polymerization shrinkage depended on the type of resin-based filling material but not on curing time. Shrinkage was not compensated by hygroscopic expansion.

Attritional wear and abrasive surface alterations of composite resin materials in vitro.

PubMed

Göhring, T N; Besek, M J; Schmidlin, P R

2002-01-01

A laboratory study was performed with 232 specimens and 72 human enamel, 24 gold, 24 ceramic and 12 composite antagonists in 22 groups to test attritional and abrasive wear behavior of composite materials compared to wear behavior of human enamel. Belleglass HP, Concept Inlay/Onlay, Targis and Targis Upgrade 99 composite resin for lab-made restorations was tested as well as Tetric Ceram and FHC Merz light as resins for direct restorations. Natural human enamel specimens served as control. All specimens were subjected to long-term thermo-mechanical loading in a computer-controlled masticator, chemical degradation and toothbrush/toothpaste abrasion. Wear of specimen in occlusal contact area (OCA), contact-free occlusal area and wear of natural enamel cusps as well as antagonists made of gold, ceramic and composite in identical form was measured after 120,000, 240,000, 640,000 and 1200,000 load cycles. A qualitative SEM analysis was performed to support quantitative data. Belleglass HP and Targis Upgrade 99 restorative materials showed wear resistance comparable to human enamel when loaded with enamel cusps. Wear of Targis versus composite and gold antagonists was significantly higher (p<0.0001). Analysis of surface alterations showed hygroscopic expansion in all composite resins during the test. As a consequence of this study, necessity to further improve physical properties of composites for long lasting restorations was obvious. Beside of attritional wear in OCA, attention must be given to stable filler-matrix interfaces and prevention of water sorption.

Effects of magnetic field treatment on dielectric properties of CCTO@Ni/PVDF composite with low concentration of ceramic fillers

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

Chi, Q. G., E-mail: qgchi@hotmail.com, E-mail: empty-cy@l63.com; State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049; Gao, L.

2015-11-15

Using melt mixing, we produced a ceramic/polymer composite with a matrix of polyvinylidene fluoride (PVDF) and a filler of 5 vol.% Ni-deposited CaCu{sub 3}Ti{sub 4}O{sub 12} core-shell ceramic particles (CCTO@Ni), and studied its prominent dielectric characteristics for the first. Its phase composition and morphology were analyzed by X-ray diffraction and scanning electron microscopy, respectively. After treating the composite films with various durations of a magnetic field treatment, we compared their dielectric properties. We found that the CCTO@Ni ceramic had a typical urchin-like core-shell structure, and that different durations of the magnetic field treatment produced different distributions of ceramic particles inmore » the PVDF matrix. The dielectric permittivity of the untreated CCTO@Ni/PVDF composite was 20% higher than that of neat PVDF, and it had a low loss tangent. However, only the composite treated for 30 min in the magnetic field had an ultra-high dielectric permittivity of 1.41 × 10{sup 4} at 10 Hz, three orders of magnitude higher than the untreated composite, which declined dramatically with increasing frequency, accompanied by an insulating-conducting phase transition and an increase in loss tangent. Our results demonstrate that changes in the dielectric properties of PVDF composites with magnetic field treatment are closely related to the percolation effect and interfacial polarization.« less

Effect of filler properties in composite resins on light transmittance characteristics and color.

PubMed

Arikawa, Hiroyuki; Kanie, Takahito; Fujii, Koichi; Takahashi, Hideo; Ban, Seiji

2007-01-01

The purpose of this investigation was to examine the effect of filler particle size and shape as well as filler content on light transmittance characteristics and color of experimental composite resins. A mixture of 30 mol% Bis-GMA and 70 mol% TEGDMA was prepared as a base monomer and to which a photoinitiator (camphorquinone) and a co-initiator (N,N-dimethylaminoethyl methacrylate) were added. Four different irregular- and spherical-shaped filler types with an average particle size of 1.9-11.1 microm were added to the mixture in three different filler contents of 20, 30, and 40 vol%. Light transmittance characteristics including light diffusion characteristics of the materials were evaluated. Color values and color differences among filler contents of the materials were also determined. Materials containing smaller and irregular-shaped fillers showed higher light transmittance and diffusion angle distribution with a sharper peak, as compared with those containing larger and spherical-shape fillers. It was also found that there was a significant correlation between the specific surface area of fillers and the color difference of the materials containing the fillers. Our results indicated that the shape of filler particles, as well as particle size and filler content, significantly affected the light transmittance characteristics--including light diffusion characteristics--and color of composite resins.

Electrical modulus analysis on the Ni/CCTO/PVDF system near the percolation threshold

NASA Astrophysics Data System (ADS)

Yang, Wenhu; Yu, Shuhui; Sun, Rong; Ke, Shanming; Huang, Haitao; Du, Ruxu

2011-11-01

A type of Ni/CCTO/PVDF three-phase percolative composite was prepared, in which the filler content (volume fraction) of Ni and CCTO was set at 60 vol%. The dependence of permittivity, electrical modulus and ac conductivity on the concentration of Ni and CCTO fillers near the percolation threshold was investigated in detail. The permittivity of the composites dramatically increased as the Ni content approached 24 vol%. This unique physical mechanism was realized as the formation of conductive channels near the percolation threshold. Analysis on the electrical modulus showed that the conductive channels are governed by three relaxation processes induced by the fillers (Ni, CCTO) and PVDF matrix, which are the interfacial polarization derived from the interfaces between fillers (Ni, CCTO) and PVDF matrix, and the polarization of CCTO ceramic filler and PVDF matrix. The conductivity behaviour with various Ni loadings and temperature suggested that the transition from an insulating to a conducting state should be induced by charge tunnelling between Ni-Ni particles, Ni-CCTO fillers and Ni-PVDF matrix. These findings demonstrated that the tunnelling conduction in the composite can be attributed to the unique physical mechanism near the percolation threshold.

STS-114: Discovery Day 6 Post MMT Meeting

NASA Technical Reports Server (NTRS)

2005-01-01

Wane Hill, Deputy Manager of the Space Shuttle Program, and Steve Poulos, Manager, Orbiter Project Office discussed damage assessments caused during ascent. Steve further detailed the damage analysis and assessments with chart presentation of composite tile damage and gap filler sites evaluation, protruding ceramic shim, left wing tile damage, comparisons of ground test results versus FD5 focused inspection, and the window 1 blanket. Gap fillers, the STS-73, thermal protection, temperature range, heating and heating range, aerodynamics, aerothermodynamics, risk, foam damage, tile adhesions, and extravehicular activities are topics covered with the News media.

Thermally stimulated depolarization currents and dielectric properties of Mg0.95Ca0.05TiO3 filled HDPE composites

NASA Astrophysics Data System (ADS)

Shi, Yunzhou; Zhang, Li; Zhang, Jie; Yue, Zhenxing

2017-12-01

Mg0.95Ca0.05TiO3 (MCT) filled high density polyethylene (HDPE) composites were prepared by twin-screw extrusion followed by hot pressing technique. The thermally stimulated depolarization current (TSDC) measurement was performed to analyze the contribution of charge distribution and interfacial characteristics to the dielectric loss. TSDC spectra under different polarization conditions show that the introduction of ceramic fillers engenders shallow traps in the vicinity of ceramic-polymer interface, which hinders the injection of space charge from the electrode into the polymer matrix. In the composite materials applied to an external field, charges tend to be captured by these traps. The temperature dependence of relative permittivity and dielectric loss of the composites was measured, and a strong reliance of dielectric loss on temperature was observed. In the heating process, the release of charges accumulating at interfacial region is considered to contribute to the rise in dielectric loss with the increase of temperature.

Freestanding, heat resistant microporous film for use in energy storage devices

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

Pekala, Richard W.; Cherukupalli, Srinivas; Waterhouse, Robert R.

Preferred embodiments of a freestanding, heat resistant microporous polymer film (10) constructed for use in an energy storage device (70, 100) implements one or more of the following approaches to exhibit excellent high temperature mechanical and dimensional stability: incorporation into a porous polyolefin film of sufficiently high loading levels of inorganic or ceramic filler material (16) to maintain porosity (18) and achieve low thermal shrinkage; use of crosslinkable polyethylene to contribute to crosslinking the polymer matrix (14) in a highly inorganic material-filled polyolefin film; and heat treating or annealing of biaxially oriented, highly inorganic material-filled polyolefin film above the meltingmore » point temperature of the polymer matrix to reduce residual stress while maintaining high porosity. The freestanding, heat resistant microporous polymer film embodiments exhibit extremely low resistance, as evidenced by MacMullin numbers of less than 4.5.« less

Filler particle size and composite resin classification systems.

PubMed

Lang, B R; Jaarda, M; Wang, R F

1992-11-01

The currently used composite resin classification systems need review if they are to continue to serve as descriptives and quantitative parameters denoting the filler particle content of these materials. Examination of the particles in 12 composite resins using a technique of washing the filler particles from the matrix of the composite resin was presented as yet another method of grouping composites according to filler particle content. Light microscopic examination of the filler particles that remained provided a separation of the 12 materials into four easily distinguished groups based on filler particle sizes. The wear of the 12 composite resins determined in a previous study was examined in relation to the classification of the materials by the currently available systems. The wear values were also examined using the groupings of the materials according to their filler particle sizes as determined by separating the particles from the matrix by the washing technique. Grouping composites on the basis of the filler particle sizes found after washing was easily correlated with wear and supported the suggestion that composites with smaller filler particles wear less.

Development of sputtered techniques for thrust chambers, task 1. [evaluation of filler materials for regeneratively cooled thrust chambers

NASA Technical Reports Server (NTRS)

Mullaly, J. R.; Schmid, T. E.; Hecht, R. J.

1974-01-01

Filler materials proposed for use in the sputter fabrication regeneratively cooled thrust chambers were evaluated. Low melting castable alloys, CERROBEND. CERROCAST, and CERROTRU, slurry applied SERMETEL 481 and flame-sprayed aluminum were investigated as filler materials. Sputter deposition from a cylindrical cathode inverted magnestron was used to apply an OFHC copper closeout layer to filled OFHC copper ribbed-wall cylindrical substrates. The sputtered closeout layer structure was evaluated with respect to filler material contamination, predeposition machining and finishing operations, and deposition parameters. The application of aluminum by flame-spraying resulted in excessiver filler porosity. Though the outgassing from this porosity was found to be detrimental to the closeout layer structure, bond strengths in excess of 10,500 psi were achieved. Removal of the aluminum from the grooves was readily accomplished by leaching in a 7.0 molar solution of sodium hydroxide at 353 K. Of the other filler materials evaluated, CERROTRU was found to be the most suitable material with respect to completely filling the ribbed-wall cylinders and vacuum system compatibility. However, bond contamination resulted in low closeout layer bond strength with the CERROTRU filler. CERROBEND, CERROCAST, and SERMETEL 481 were found to be unacceptable as filler materials.

Hardness of model dental composites - the effect of filler volume fraction and silanation.

PubMed

McCabe, J F; Wassell, R W

1999-05-01

The relationship between structure and mechanical properties for dental composites has often proved difficult to determine due to the use of commercially available materials having a number of differences in composition i.e. different type of resin, different type of filler, etc. This makes a scientific study of any one variable such as filler content difficult if not impossible. In the current study it was the aim to test the hypothesis that hardness measurements of dental composites could be used to monitor the status of the resin-filler interface and to determine the efficacy of any particle silanation process. Ten model composites formulated from a single batch of resin and containing a common type of glass filler were formulated to contain varying amounts of filler. Some materials contained silanated filler, others contained unsilanated filler. Specimens were prepared and stored in water and hardness (Vickers') was determined at 24 h using loads of 50, 100, 200 and 300 g. Composites containing silanated fillers were significantly harder than materials containing unsilanated fillers. For unsilanated products hardness was independent of applied load and in this respect they behaved like homogeneous materials. For composites containing silanated fillers there was a marked increase in measured hardness as applied load was increased. This suggests that the hardness-load profile could be used to monitor the status of the resin-filler interface. Copyright 1999 Kluwer Academic Publishers

The Apparent Contact Angle and Wetted Area of Active Alloys on Silicon Carbide as a Function of the Temperature and the Surface Roughness: A Multivariate Approach

NASA Astrophysics Data System (ADS)

Tillmann, Wolfgang; Pfeiffer, Jan; Wojarski, Lukas

2015-08-01

Despite the broad field of applications for active filler alloys for brazing ceramics, as well as intense research work on the wetting and spreading behavior of these alloys on ceramic surfaces within the last decades, the manufactured joints still exhibit significant variations in their properties due to the high sensitivity of the alloys to changing brazing conditions. This increases the need for investigations of the wetting and spreading behavior of filler alloys with regard to the dominating influences combined with their interdependencies, instead of solely focusing on single parameter investigations. In this regard, measurements of the wetting angle and area were conducted at solidified AgCuTi and CuSnTi alloys on SiC substrates. Based on these measurements, a regression model was generated, illustrating the influence of the brazing temperature, the roughness of the faying surfaces, the furnace atmosphere, and their interdependencies on the wetting and spreading behavior of the filler alloys. It was revealed that the behavior of the melts was significantly influenced by the varied brazing parameters, as well as by their interdependencies. This result was also predicted by the developed model and showed a high accuracy.

Mechanical behavior of bioactive composite cements consisting of resin and glass-ceramic powder in a simulated body fluid: effect of silane coupling agent.

PubMed

Miyata, N; Matsuura, W; Kokubo, T; Nakamura, T

2004-09-01

Time-dependent strength behavior was investigated for bisphenol-a-glycidyl methacrylate/triethylene glycol dimethacrylate (Bis-GMA/TEGDMA) resin cements combined with glass-ceramic A-W filler treated with various kinds of silane coupling agents. The fracture strength of the composite resin cements was measured by three-point bending as a function of stressing rate in a simulated body fluid (SBF), and thereby the stress-corrosion susceptibility constant was evaluated. The fracture strength was found to depend on the kind of coupling agent used. For the present Bis-GMA/TEGDMA resin, the silane coupling agents without hydrophilic amine groups can be used to obtain good adhesion between resin and A-W filler owing to their nature of co-polymerizing with the resin. On the other hand, all the composite resin cements showed nearly the same degree of stress-corrosion susceptibility whether the A-W fillers were treated or untreated with silane coupling agents. This means that the stress-corrosion susceptibility of the present composite cements is predominantly affected by that of the matrix resin. Thus, the microcrack formation and growth at the resin matrix near particle - resin interface were thought to determine overall time-dependent strength behavior of the composite cements.

Antibacterial activity of agricultural waste derived wollastonite doped with copper for bone tissue engineering.

PubMed

Azeena, S; Subhapradha, N; Selvamurugan, N; Narayan, S; Srinivasan, N; Murugesan, R; Chung, T W; Moorthi, A

2017-02-01

Bioactive ceramic materials with metal ions generation brought great attention in the class of biomaterials development and widely employed as a filler material for bone tissue regeneration. The present study aimed to fabricate calcium silicate based ceramic material doped with copper metal particles by sol-gel method. Rice straw of agricultural waste was utilized as a source material to synthesize wollastonite, then wollastonite was doped with copper to fabricate copper doped wollastonite (Cu-Ws) particles. The synthesized materials were subjected to physio-chemical characterization by TEM, DLS, FTIR, XRD and DSC analysis. It was found that the sizes of the WS particles was around 900nm, while adding copper the size was increased upto 1184nm and the addition of copper to the material sharpening the peak. The release of Cu ions was estimated by ICP analysis. The anti-bacterial potentiality of the particles suggested that better microbial growth inhibition against E. coli (Gram negative) and S. aureus (Gram positive) strains from ATCC, in which the growth inhibition was more significant against S. aureus. The biocompatibility in mouse Mesenchymal Stem cells (mMSC) showed the non-toxic effect up to 0.05mg/ml concentration while the increase in concentration was found to be toxic to the cells. So the particles may have better potential application with the challenging prevention of post implantation infection in the field of bone tissue engineering (BTE). Copyright © 2016. Published by Elsevier B.V.

Novel Dental Composites Reinforced with Zirconia-Silica Ceramic Nanofibers

PubMed Central

Guo, Guangqing; Fan, Yuwei; Zhang, Jian-Feng; Hagan, Joseph; Xu, Xiaoming

2011-01-01

Objective To fabricate and characterize dental composites reinforced with various amounts of zirconia-silica (ZS) or zirconia-yttria-silica (ZYS) ceramic nanofibers. Methods Control composites (70 wt% glass particle filler, no nanofibers) and experimental composites (2.5, 5.0, and 7.5 wt% ZS or ZYS nanofibers replacing glass particle filler) were prepared by blending 29 wt% dental resin monomers, 70 wt% filler, and 1.0 wt% initiator, and polymerized by either heat or dental curing light. Flexural strength (FS), flexural modulus (FM), energy at break (EAB), and fracture toughness (FT) were tested after the specimens were stored in 37 °C deionized water for 24 h, 3 months, or 6 months. Degree of conversion (DC) of monomers in composites was measured using Fourier transformed near-infrared (FT-NIR) spectroscopy. Fractured surfaces were observed by field-emission scanning electron microscope (FE-SEM). The data were analyzed using ANOVA with Tukey’s Honestly Significant Differences test used for post hoc analysis. Results Reinforcement of dental composites with ZS or ZYS nanofibers (2.5% or 5.0%) can significantly increase the FS, FM and EAB of dental composites over the control. Further increase the content of ZS nanofiber (7.5%), however, decreases these properties (although they are still higher than those of the control). Addition of nanofibers did not decrease the long-term mechanical properties of these composites. All ZS reinforced composites (containing 2.5%, 5.0% and 7.5% ZS nanofibers) exhibit significantly higher fracture toughness than the control. The DC of the composites decreases with ZS nanofiber content. Significance Incorporation of ceramic nanofibers in dental composites can significantly improve their mechanical properties and fracture toughness and thus may extend their service life. PMID:22153326

Serpentinitic waste materials: possible reuses and critical issues

NASA Astrophysics Data System (ADS)

Cavallo, Alessandro

2017-04-01

The extraction and processing of marbles, rocks and granites produces a significant amount of waste materials, in the form of shapeless blocks, scraps, gravel and sludge. Current regulations and a greater concern to the environment promote the reuse of these wastes: quartz-feldspathic materials are successfully used for ceramics, crushed porphyry as track ballast, whereas carbonatic wastes for lime, cement and fillers. However, there are currently no reuses for serpentinitic materials: a striking example is represented by the Valmalenco area (central Alps, northern Italy), a relatively small productive district. In this area 22 different enterprises operate in the quarrying and/or processing of serpentinites with various textures, schistose to massive, and color shades; the commercial products are used all over the world and are known with many commercial names. The total volume extracted in the quarries is estimated around 68000 m3/yr. and the resulting commercial blocks and products can be estimated around the 40 - 50 % of the extracted material. The processing wastes can vary significantly according to the finished product: 35 % of waste can be estimated in the case of slab production, whereas 50 % can be estimated in the case of gang-saw cutting of massive serpentinite blocks. The total estimate of the processing rock waste in the Valmalenco area is about 12700 m3/yr; together with the quarry waste, the total amount of waste produced in the area is more than 43000 m3/yr. The sludge (approximately 12000 m3/yr, more than 95 % has grain size < 50 micron) mainly derives from the cutting (by diamond disk and gang-saw) and polishing of massive serpentinites; it is filter-pressed before disposal (water content ranging from 11.5 to 19.4 wt. %). All the different waste materials (85 samples) were characterized by quantitative XRPD (FULLPAT software), whole-rock geochemistry (ICP-AES, ICP-MS and Leco®) and SEM-EDS. The mineralogical composition is quite variable from quarry to quarry, with abundant antigorite (up to 90 wt. %) and olivine (up to 38 wt. %), and variable contents of diopside, chlorite, magnetite, chromite and brucite. The chemical composition reflects the protolith: MgO 35.1 - 42.7 wt. %, SiO2 38.8 - 42.3 wt. %, Fe2O3 7.1 - 8.8 wt. %, Al2O3 0.9 - 2.8 wt. %, CaO 0.2 - 3.1 wt. %, Cr2O3 0.26 - 0.35 wt. %, Ni 1800 - 2100 ppm; little differences can be observed in trace elements. SEM-EDS investigations evidenced little amounts of chrysotile asbestos fibers (generally < 1000 ppm, mean values 200 - 400 ppm), deriving from cracks, fissures and veins of the waste blocks. Very few published studies on the reuse of serpentinitic wastes can be found. Finely ground antigorite-rich materials could be used as filler for plastics (instead of talc), whereas olivine-rich wastes as a reactive fixing carbon dioxide (as carbonates) released during the use of fossil fuels. In the ceramic industry, the most promising target is represented by forsterite and/or high-MgO ceramics and forsterite refractories (with periclase addition), but also by cordierite ceramics (adding kaolin) and high-hardness vitroceramics. The real possibility of an industrial use of serpentinitic materials will require much more experimental work, because no relevant previous studies are available. Special care must be taken to avoid chrysotile asbestos contamination.

Preparation of ceramic filler from reusing sewage sludge and application in biological aerated filter for soy protein secondary wastewater treatment.

PubMed

Wu, Suqing; Qi, Yuanfeng; Yue, Qinyan; Gao, Baoyu; Gao, Yue; Fan, Chunzhen; He, Shengbing

2015-01-01

Dehydrated sewage sludge (DSS) and clay used as raw materials for preparation of novel media-sludge ceramic filler (SCF) and SCF employed in a lab-scale up-flow biological aerated filter (BAF) were investigated for soy protein secondary wastewater treatment. Single factor experiments were designed to investigate the preparation of SCF, and the characteristics (microstructure properties, toxic metal leaching property and other physical properties) of SCF prepared under the optimum conditions were examined. The influences of media height, hydraulic retention time (HRT) and air-liquid ratio (A/L) on chemical oxygen demand (CODcr) and ammonia nitrogen (NH4(+)-N) removal rate were studied. The results showed that the optimum addition of DSS was approximately 25.0 wt% according to the physical properties of SCF (expansion ratio of 53.0%, v/v, water absorption of 8.24 wt%, bulk density of 350.4 kg m(-3) and grain density of 931.5 kg m(-3)), and the optimum conditions of BAF system were media height of 75.0 cm, HRT of 10.0 h and A/L of 15:1 in terms of CODcr and NH4(+)-N removal rate (91.02% and 90.48%, respectively). Additionally, CODcr and NH4(+)-N (81.6 and 15.3 mg L(-1), respectively) in the final effluent of BAF system met the national standard (CODcr ≤ 100 mg L(-1), NH4(+)-N ≤ 25.0 mg L(-1), GB 18918-2002, secondary standard). Copyright © 2014 Elsevier B.V. All rights reserved.

Wetting and spreading behavior of molten brazing filler metallic alloys on metallic substrate

NASA Astrophysics Data System (ADS)

Kogi, Satoshi; Kajiura, Tetsurou; Hanada, Yukiakira; Miyazawa, Yasuyuki

2014-08-01

Wetting and spreading of molten brazing filler material are important factors that influence the brazing ability of a joint to be brazed. Several investigations into the wetting ability of a brazing filler alloy and its surface tension in molten state, in addition to effects of brazing time and temperature on the contact angle, have been carried out. In general, dissimilar-metals brazing technology and high-performance brazed joint are necessities for the manufacturing field in the near future. Therefore, to address this requirement, more such studies on wetting and spreading of filler material are required for a deeper understanding. Generally, surface roughness and surface conditions affect spreading of molten brazing filler material during brazing. Wetting by and interfacial reactions of the molten brazing filler material with the metallic substrate, especially, affect strongly the spreading of the filler material. In this study, the effects of surface roughness and surface conditions on the spreading of molten brazing filler metallic alloys were investigated. Ag-(40-x)Cu-xIn and Ag- (40-x)Cu-xSn (x=5, 10, 15, 20, 25) alloys were used as brazing filler materials. A mild-steel square plate (S45C (JIS); side: 30 mm; thickness: 3mm) was employed as the substrate. A few surfaces with varying roughness were prepared using emery paper. Brazing filler material and metallic base plate were first washed with acetone, and then a flux was applied to them. The filler, 50 mg, was placed on the center of the metallic base with the flux. A spreading test was performed under Ar gas using an electrically heated furnace, after which, the original spreading area, defined as the sessile drop area, and the apparent spreading area, produced by the capillary grooves, were both evaluated. It was observed that the spreading area decreased with increasing In and Sn content.

Reaction layer characterization of the braze joint of silicon nitride to stainless steel

NASA Astrophysics Data System (ADS)

Xu, R.; Indacochea, J. E.

1994-10-01

This investigation studies the role of titanium in the development of the reaction layer in braze joining silicon nitride to stainless steel using titanium-active copper-silver filler metals. This reaction layer formed as a result of titanium diffusing to the filler metal/silicon nitride interface and reacting with the silicon nitride to form the intermetallics, titanium nitride (TiN) and titanium suicide (Ti 5Si3). This reaction layer, as recognized in the literature, allows wetting of the ceramic substrate by the molten filler metal. The reaction layer thickness increases with temperature and time. Its growth rate obeys the parabolic relationship. Activation energies of 220.1 and 210.9 kj/mol were calculated for growth of the reaction layer for the two filler metals used. These values are close to the activation energy of nitrogen in TiN (217.6 kj/mol). Two filler metals were used in this study, Ticusil (68.8 wt% Ag, 26.7 wt% Cu, 4.5 wt% Ti) and CB4 (70.5 wt% Ag, 26.5 wt% Cu, 3.0 wt% Ti). The joints were processed in vacuum at temperatures of 840 to 900 °C at various times. Bonding strength is affected by reaction layer thickness in the absence of Ti-Cu intermetallics in the filler metal matrix.

Development of piezoelectric composites for transducers

NASA Astrophysics Data System (ADS)

Safari, A.

1994-07-01

For the past decade and a half, many different types of piezoelectric ceramic-polymer composites have been developed intended for transducer applications. These diphasic composites are prepared from non-active polymer, such as epoxy, and piezoelectric ceramic, such as PZT, in the form of filler powders, elongated fibers, multilayer and more complex three-dimensional structures. For the last four years, most of the efforts have been given to producing large area and fine scale PZT fiber composites. In this paper, processing of piezoelectric ceramic-polymer composites with various connectivity patterns are reviewed. Development of fine scale piezoelectric composites by lost mold, injection molding and the relic method are described. Research activities of different groups for preparing large area piezocomposites for hydrophone and actuator applications are briefly reviewed. Initial development of electrostrictive ceramics and composites are also

Advanced inorganic separators for alkaline batteries

NASA Technical Reports Server (NTRS)

Sheibley, D. W. (Inventor)

1982-01-01

A flexible, porous battery separator comprising a coating applied to a porous, flexible substrate is described. The coating comprises: (1) a thermoplastic rubber-based resin which is insoluble and unreactive in the alkaline electrolyte; (2) a polar organic plasticizer which is reactive with the alkaline electrolyte to produce a reaction product which contains a hydroxyl group and/or a carboxylic acid group; and (3) a mixture of polar particulate filler materials which are unreactive with the electrolyte, the mixture comprising at least one first filler material having a surface area of greater than 25 meters sq/gram, at least one second filler material having a surface area of 10 to 25 sq meters/gram, wherein the volume of the mixture of filler materials is less than 45% of the total volume of the fillers and the binder, the filler surface area per gram of binder is about 20 to 60 sq meters/gram, and the amount of plasticizer is sufficient to coat each filler particle. A method of forming the battery separator is also described.

Advanced inorganic separators for alkaline batteries and method of making the same

NASA Technical Reports Server (NTRS)

Sheibley, D. W. (Inventor)

1983-01-01

A flexible, porous battery separator includes a coating applied to a porous, flexible substrate. The coating comprises: (1) a thermoplastic rubber-based resin which is insoluble and unreactive in the alkaline electrolyte, (2) a polar organic plasticizer which is reactive with the alkaline electrolyte to produce a reaction product which contains a hydroxyl group and/or a carboxylic acid group, and (3) a mixture of polar particulate filler materials which are unreactive with the electrode. The mixture comprises at least one first filler material having a surface area of greater than 25 sq meters/gram, at last one second filler material having a surface area of 10 to 25 sq meters/gram. The volume of the mixture of filler materials is less than 45% of the total volume of the fillers and the binder. The filler surface area per gram of binder is about 20 to 60 sq meters/gram, and the amount of plasticizer is sufficient to coat each filler particle.

Elastomer actuators: systematic improvement in properties by use of composite materials

NASA Astrophysics Data System (ADS)

Molberg, Martin; Leterrier, Yves; Plummer, Christopher J. G.; Löwe, Christiane; Opris, Dorina M.; Clemens, Frank; Månson, Jan-Anders E.

2010-04-01

Dielectric elastomer actuators (DEAs) have attracted increasing attention over the last few years owing to their outstanding properties, e.g. their large actuation strains, high energy density, and pliability, which have opened up a wide spectrum of potential applications in fields ranging from microengineering to medical prosthetics. There is consequently a huge demand for new elastomer materials with improved properties to enhance the performance of DEAs and to overcome the limitations associated with currently available materials, such as the need for high activation voltages and the poor long-term stability. The electrostatic pressure that activates dielectric elastomers can be increased by higher permittivity of the elastomer and thus may lead to lower activation voltages. This has led us to consider composite elastomeric dielectrics based on thermoplastic elastomers or PDMS, and conductive polyaniline or ceramic (soft doped PZT) powder fillers. The potential of such materials and strategies to counter the adverse effects of increased conductivity and elastic modulus are discussed.

Hydroxyapatite-based porous aggregates: physico-chemical nature, structure, texture and architecture.

PubMed

Fabbri, M; Celotti, G C; Ravaglioli, A

1995-02-01

At the request of medical teams from the maxillofacial sector, a highly porous ceramic support based on hydroxyapatite of around 70-80% porosity was produced with a pore size distribution similar to bone texture (< 10 microns, approximately 3 vol%; 10-150 microns, approximately 110 vol%; > 150 microns, approximately 86 vol%). The ceramic substrates were conceived not only as a fillers for bone cavities, but also for use as drug dispensers and as supports to host cells to produce particular therapeutic agents. A method is suggested to obtain a substrate of high porosity, exploiting the impregnation of spongy substrate with hydroxyapatite ceramic particles. X-ray and scanning electron microscopy analyses were carried out to evaluate the nature of the new ceramic support in comparison with the most common commercial product; pore size distribution and porosity were controlled to known hydroxyapatite ceramic architecture for the different possible uses.

Thermal conductivity of 2D nano-structured graphitic materials and their composites with epoxy resins

NASA Astrophysics Data System (ADS)

Mu, Mulan; Wan, Chaoying; McNally, Tony

2017-12-01

The outstanding thermal conductivity (λ) of graphene and its derivatives offers a potential route to enhance the thermal conductivity of epoxy resins. Key challenges still need to be overcome to ensure effective dispersion and distribution of 2D graphitic fillers throughout the epoxy matrix. 2D filler type, morphology, surface chemistry and dimensions are all important factors in determining filler thermal conductivity and de facto the thermal conductivity of the composite material. To achieve significant enhancement in the thermal conductivity of epoxy composites, different strategies are required to minimise phonon scattering at the interface between the nano-filler and epoxy matrix, including chemical functionalisation of the filler surfaces such that interactions between filler and matrix are promoted and interfacial thermal resistance (ITR) reduced. The combination of graphitic fillers with dimensions on different length scales can potentially form an interconnected multi-dimensional filler network and, thus contribute to enhanced thermal conduction. In this review, we describe the relevant properties of different 2D nano-structured graphitic materials and the factors which determine the translation of the intrinsic thermal conductivity of these 2D materials to epoxy resins. The key challenges and perspectives with regard achieving epoxy composites with significantly enhanced thermal conductivity on addition of 2D graphitic materials are presented.

Sol-Gel Derived Hafnia Coatings

NASA Technical Reports Server (NTRS)

Feldman, Jay D.; Stackpoole, Mairead; Blum, Yigal; Sacks, Michael; Ellerby, Don; Johnson, Sylvia M.; Venkatapathy, Ethiras (Technical Monitor)

2002-01-01

Sol-gel derived hafnia coatings are being developed to provide an oxidation protection layer on ultra-high temperature ceramics for potential use in turbine engines (ultra-efficient engine technology being developed by NASA). Coatings using hafnia sol hafnia filler particles will be discussed along with sol synthesis and characterization.

Vertically Aligned and Continuous Nanoscale Ceramic-Polymer Interfaces in Composite Solid Polymer Electrolytes for Enhanced Ionic Conductivity.

PubMed

Zhang, Xiaokun; Xie, Jin; Shi, Feifei; Lin, Dingchang; Liu, Yayuan; Liu, Wei; Pei, Allen; Gong, Yongji; Wang, Hongxia; Liu, Kai; Xiang, Yong; Cui, Yi

2018-06-13

Among all solid electrolytes, composite solid polymer electrolytes, comprised of polymer matrix and ceramic fillers, garner great interest due to the enhancement of ionic conductivity and mechanical properties derived from ceramic-polymer interactions. Here, we report a composite electrolyte with densely packed, vertically aligned, and continuous nanoscale ceramic-polymer interfaces, using surface-modified anodized aluminum oxide as the ceramic scaffold and poly(ethylene oxide) as the polymer matrix. The fast Li + transport along the ceramic-polymer interfaces was proven experimentally for the first time, and an interfacial ionic conductivity higher than 10 -3 S/cm at 0 °C was predicted. The presented composite solid electrolyte achieved an ionic conductivity as high as 5.82 × 10 -4 S/cm at the electrode level. The vertically aligned interfacial structure in the composite electrolytes enables the viable application of the composite solid electrolyte with superior ionic conductivity and high hardness, allowing Li-Li cells to be cycled at a small polarization without Li dendrite penetration.

Nanostructured Materials Utilized in Biopolymer-based Plastics for Food Packaging Applications.

PubMed

Ghanbarzadeh, Babak; Oleyaei, Seyed Amir; Almasi, Hadi

2015-01-01

Most materials currently used for food packaging are nondegradable, generating environmental problems. Several biopolymers have been exploited to develop materials for ecofriendly food packaging. However, the use of biopolymers has been limited because of their usually poor mechanical and barrier properties, which may be improved by adding reinforcing compounds (fillers), forming composites. Most reinforced materials present poor matrix-filler interactions, which tend to improve with decreasing filler dimensions. The use of fillers with at least one nanoscale dimension (nanoparticles) produces nanocomposites. Nanoparticles have proportionally larger surface area than their microscale counterparts, which favors the filler-matrix interactions and the performance of the resulting material. Besides nanoreinforcements, nanoparticles can have other functions when added to a polymer, such as antimicrobial activity, etc. in this review paper, the structure and properties of main kinds of nanostructured materials which have been studied to use as nanofiller in biopolymer matrices are overviewed, as well as their effects and applications.

Surface-modified Ba(Zr0.3Ti0.7)O3 nanofibers by polyvinylpyrrolidone filler for poly(vinylidene fluoride) composites with enhanced dielectric constant and energy storage density.

PubMed

Liu, Shaohui; Xue, Shuangxi; Xiu, Shaomei; Shen, Bo; Zhai, Jiwei

2016-05-17

Ferroelectric-relaxor behavior of Ba(Zr0.3Ti0.7)O3 nanofibers (BZT NF) with a large aspect ratio were prepared via electrospinning and surface modified by PVP as dielectric fillers. The nanocomposite flexible films based on surface modified BZT NF and polyvinylidene fluoride (PVDF) were fabricated via a solution casting. The results show that the surface-modified BZT NF fillers are highly dispersed and well integrated in the PVDF nanocomposites. The nanocomposites exhibit enhanced dielectric constant and reduced loss tangents at a low volume fraction of surface-modified BZT NF. The polymer nanocomposites maintain a relatively high breakdown strength, which is favorable for enhancing energy storage density in the nanocomposites. The nanocomposite containing of 2.5 vol. % of PVP modified BZT NF exhibits energy density as high as 6.3 J/cm(3) at 3800 kV/cm, which is more than doubled that of the pure PVDF of 2.8 J/cm(3) at 4000 kV/cm. Such significant enhancement could be attributed to the combined effects of the surface modification and large aspect ratio of the BZT NF. This work may provide a route for using the surface modified ferroelectric-relaxor behavior of ceramic nanofibers to enhance the dielectric energy density in ceramic-polymer nanocomposites.

Microstructurally tailored ceramics for advanced energy applications by thermoreversible gelcasting

NASA Astrophysics Data System (ADS)

Shanti, Noah Omar

Thermoreversible gelcasting (TRG) is an advantageous technique for rapidly producing bulk, net-shape ceramics and laminates. In this method, ceramic powder is suspended in warm acrylate triblock copolymer/alcohol solutions that reversibly gel upon cooling by the formation of endblock aggregates, to produce slurries which are cast into molds. Gel properties can be tailored by controlling the endblock and midblock lengths of the copolymer network-former and selecting an appropriate alcohol solvent. This research focuses on expanding and improving TRG techniques, focusing specifically on advanced energy applications including the solid oxide fuel cell (SOFC). Rapid drying of filled gels can lead to warping and cracking caused by high differential capillary stresses. A new drying technique using concentrated, alcohol-based solutions as liquid desiccants (LDs) to greatly reduce warping is introduced. The optimal LD is a poly(tert-butyl acrylate)/isopropyl alcohol solution with 5 mol% tert-butyl acrylate units. Alcohol emissions during drying are completely eliminated by combining initial drying in an LD with final stage drying in a vacuum oven having an in-line solvent trap. Porous ceramics are important structures for many applications, including SOFCs. Pore network geometries are tailored by the addition of fugitive fillers to TRG slurries. Uniform spherical, bimodal spherical and uniform fibrous fillers are used. Three-dimensional pore structures are visualized by X-ray computed tomography, allowing for direct measurements of physical parameters such as concentration and morphology as well as transport properties such as tortuosity. Tortuosity values as low as 1.52 are achieved when 60 vol% of solids are uniform spherical filler. Functionally graded laminates with layers ranging from 10 mum to > 1 mm thick are produced with a new technique that combines TRG with tape casting. Gels used for bulk casting are not suitable for use with tape casting, and appropriate base gels are selected for this technique. Each layer is cast in a single pass, and the layers are directly laminated. The anode support, anode functional layer, and electrolyte of anode-supported SOFCs are produced using this technique. The performance of SOFCs produced this way is not yet equal to that of traditionally processed cells, but shows the promise of this technique.

Hydroxyapatite/collagen bone-like nanocomposite.

PubMed

Kikuchi, Masanori

2013-01-01

Our group has succeeded to synthesize material with bone-like nanostructure and bone-like inorganic and organic composition via self-organization mechanism between them using simultaneous titration method under controlled pH and temperature. The hydroxyapatite/collagen (HAp/Col) bone-like nanocomposite completely incorporated into bone remodeling process to be substituted by new bone. Cells cultured on the HAp/Col revealed very interesting reactions. Osteoblast-like MG63 cells showed upregulation of alkaline phosphatase >3 times greater than MG63 cells cultured on tissue culture polystyrene (TCPS). MG63 cells 3-dimensionally cultured in a "HAp/Col sponge," a porous HAp/Col having sponge-like viscoelasticity, accumulated calcium phosphate nodules on extracellular matrices they secreted. Bone marrow cells co-cultured with osteoblasts on HAp/Col differentiated to osteoclasts without differentiation supplements. This phenomenon is not found in cells cultured on hydroxyapatite ceramics and TCPS, and rarely in cells cultured on dentin. These results suggest that HAp/Col is a good candidate for tissue engineering of bone as well as bone filler. In a clinical test as a bone filler, the HAp/Col sponge was significantly better than porous β-tricalcium phosphate. The HAp/Col sponge has been approved by the Japanese government and will be used as greatly needed bone filler in patients. In addition to the above, HAp/Col coating on titanium revealed higher osteo-conductivity than HAp-coated titanium and bare titanium and improved direct bonding between titanium and newly formed bone. The HAp/Col coating may be used for metal devices requiring osseointegration.

Effect of biobased fillers nature on biodeterioration of hybrid polyethylene composites by mold fungi

NASA Astrophysics Data System (ADS)

Mastalygina, E. E.; Popov, A. A.; Pantyukhov, P. V.

2017-06-01

The paper is devoted to investigation of deterioration of natural fillers and polyethylene composites on their basis (polyethylene/filler=70/30) due to the action of mold fungi. The fillers chemical composition, dimensional parameters and biodegradability have been analyzed as factors exert a considerable impact on composite materials biodeterioration. It has been found that the principal factor determining the biodeterioration of polyethylene/filler composites by mold fungi is chemical composition of a filler and, in turn, its biodegradability. The excess of holocellulose content over lignin content and high protein content in a filler are able to induce biofouling of the polymeric composite materials. The presence of soluble and easy hydrolysed fraction in a filler increases its availability in a polymeric matrix. According to the study results, most effective natural fillers as additives stimulating polyethylene composites biodegradability are milled straw of seed flax and hydrolyzed keratin of bird’s feather.

Processing and mechanical characterization of alumina laminates

NASA Astrophysics Data System (ADS)

Montgomery, John K.

2002-08-01

Single-phase ceramics that combine property gradients or steps in monolithic bodies are sought as alternatives to ceramic composites made of dissimilar materials. This work describes novel processing methods to produce stepped-density (or laminated) alumina single-phase bodies that maintain their mechanical integrity. One arrangement consists of a stiff, dense bulk material with a thin, flaw tolerant, porous exterior layer. Another configuration consists of a lightweight, low-density bulk material with a thin, hard, wear resistant exterior layer. Alumina laminates with strong interfaces have been successfully produced in this work using two different direct-casting processes. Gelcasting is a useful near-net shape processing technique that has been combined with several techniques, such as reaction bonding of aluminum oxide and the use of starch as a fugative filler, to successfully produced stepped-density alumina laminates. The other direct casting process that has been developed in this work is thermoreversible gelcasting (TRG). This is a reversible gelation process that has been used to produce near-net shape dense ceramic bodies. Also, individual layers can be stacked together and heated to produce laminates. Bilayer laminate samples were produced with varied thickness of porous and dense layers. It was shown that due to the difference in modulus and hardness, transverse cracking is found upon Hertzian contact when the dense layer is on the exterior. In the opposite arrangement, compacted damage zones formed in the porous material and no damage occurred in the underlying dense layer. Flaw tolerant behavior of the porous exterior/dense underlayer was examined by measuring biaxial strength as a function of Vickers indentation load. It was found that the thinnest layer of porous material results in the greatest flaw tolerance. Also, higher strength was exhibited at large indentation loads when compared to dense monoliths. The calculated stresses on the surfaces and interface afforded an explanation of the behavior that failure initiates at the interface between the layers for the thinnest configuration, rather than the sample surface.

Production of Ultrafine, High-purity Ceramic Powders Using the US Bureau of Mines Developed Turbomill

NASA Technical Reports Server (NTRS)

Hoyer, Jesse L.

1993-01-01

Turbomilling, an innovative grinding technology developed by the U.S. Bureau of Mines in the early 1960's for delaminating filler-grade kaolinitic clays, has been expanded into the areas of particle size reduction, material mixing, and process reaction kinetics. The turbomill, originally called an attrition grinder, has been used for particle size reduction of many minerals, including natural and synthetic mica, pyrophyllite, talc, and marble. In recent years, an all-polymer version of the turbomill has been used to produce ultrafine, high-purity, advanced ceramic powders such as SiC, Si3N4, TiB2, and ZrO2. In addition to particle size reduction, the turbomill has been used to produce intimate mixtures of high surface area powders and whiskers. Raw materials, TiN, AlN, and Al2O3, used to produce a titanium nitride/aluminum oxynitride (TiN/AlON) composite, were mixed in the turbomill, resulting in strength increases over samples prepared by dry ball milling. Using the turbomill as a leach vessel, it was found that 90.4 pct of the copper was extracted from the chalcopyrite during a 4-hour leach test in ferric sulfate versus conventional processing which involves either roasting of the ore for Cu recovery or leaching of the ore for several days.

Improving the degradation behavior and in vitro biological property of nano-hydroxyapatite surface- grafted with the assist of citric acid.

PubMed

Jiang, Liuyun; Jiang, Lixin; Xiong, Chengdong; Su, Shengpei

2016-10-01

To obtain ideal nano-hydroxyapatite(n-HA) filler for poly(lactide-co-glycolide) (PLGA), a new surface-grafting with the assist of citric acid for nano-hydroxyapatite (n-HA) was designed, and the effect of n-HA surface-grafted with or without citric acid on in vitro degradation behavior and cells viability was studied by the experiments of soaking in simulated body fluid (SBF) and incubating with human osteoblast-like cells (MG-63). The change of pH value, tensile strength reduction, the surface deposits, cells attachment and proliferation of samples during the soaking and incubation were investigated by means of pH meter, electromechanical universal tester, scanning electron microscope (SEM) coupled with energy-dispersive spectro-scopy (EDS), fluorescence microscope and MTT method. The results showed that the introduction of citric acid not only delayed the strength reduction during the degradation by inhibiting the detachment of n-HA from PLGA, but also endowed it better cell attachment and proliferation, suggesting that the n-HA surface-grafted with the assist of citric acid was an important bioactive ceramic fillers for PLGA used as bone materials. Copyright © 2016 Elsevier B.V. All rights reserved.

Na3.4Zr1.8Mg0.2Si2PO12 filled poly(ethylene oxide)/Na(CF3SO2)2N as flexible composite polymer electrolyte for solid-state sodium batteries

NASA Astrophysics Data System (ADS)

Zhang, Zhizhen; Xu, Kaiqi; Rong, Xiaohui; Hu, Yong-Sheng; Li, Hong; Huang, Xuejie; Chen, Liquan

2017-12-01

Solid electrolytes with high ionic conductivity and excellent electrochemical stability are of prime significance to enable the application of solid-state batteries in energy storage and conversion. In this study, solid composite polymer electrolytes (CPEs) based on sodium bis(trifluorosulfonyl) imide (NaTFSI) and poly (ethylene oxide) (PEO) incorporated with active ceramic filler (NASICON) are reported for the first time. With the addition of NASICON fillers, the thermal stability and electrochemical stability of the CPEs are improved. A high conductivity of 2.8 mS/cm (at 80 °C) is readily achieved when the content of the NASICON filler in the composite polymer reaches 50 wt%. Furthermore, Na3V2(PO4)3/CPE/Na solid-state batteries using this composite electrolyte display good rate and excellent cycle performance.

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

Lytkina, D. N., E-mail: darya-lytkina@yandex.ru; Shapovalova, Y. G., E-mail: elena.shapovalova@ro.ru; Rasskazova, L. A., E-mail: ly-2207@mail.ru

Relevance of the work is due to the need for new materials that are used in medicine (orthopedics, surgery, dentistry, and others) as a substitute for natural bone tissue injuries, fractures, etc. The aim of presented work is developing of a method of producing biocompatible materials based on polyesters of hydroxycarboxylic acids and calcium phosphate ceramic (hydroxyapatite, HA) with homogeneous distribution of the inorganic component. Bioactive composites based on poly-L-lactide (PL) and hydroxyapatite with homogeneous distribution were prepared. The results of scanning electron microscopy confirm homogeneous distribution of the inorganic filler in the polymer matrix. The positive effect of ultrasoundmore » on the homogeneity of the composites was determined. The rate of hydrolysis of composites was evaluated. The rate of hydrolysis of polylactide as an individual substance is 7 times lower than the rate of hydrolysis of the polylactide as a part of the composite. It was found that materials submarines HA composite and do not cause a negative response in the cells of the immune system, while contributing to anti-inflammatory cytokines released by cells.« less

Development of lightweight ceramic ablators and arc-jet test results

NASA Technical Reports Server (NTRS)

Tran, Huy K.

1994-01-01

Lightweight ceramic ablators (LCA's) were recently developed at Ames to investigate the use of low density fibrous substrates and organic resins as high temperature, high strength ablative heat shields. Unlike the traditional ablators, LCA's use porous ceramic/carbon fiber matrices as substrates for structural support, and polymeric resins as fillers. Several substrates and resins were selected for the initial studies, and the best performing candidates were further characterized. Three arcjet tests were conducted to determine the LCA's thermal performance and ablation characteristics in a high enthalpy, hypersonic flow environment. Mass loss and recession measurements were obtained for each sample at post test, and the recession rates were determined from high speed motion films. Surface temperatures were also obtained from optical pyrometers.

The duration of hyaluronidase and optimal timing of hyaluronic acid (HA) filler reinjection after hyaluronidase injection.

PubMed

Kim, H J; Kwon, S B; Whang, K U; Lee, J S; Park, Y L; Lee, S Y

2018-02-01

Hyaluronidase injection is a commonly performed treatment for overcorrection or misplacement of hyaluronic acid (HA) filler. Many patients often wants the HA filler reinjection after the use of hyaluronidase, though the optimal timing of reinjection of HA filler still remains unknown. To provide the optimal time interval between hyaluronidase injections and HA filler reinjections. 6 Sprague-Dawley rats were injected with single monophasic HA filler. 1 week after injection, the injected sites were treated with hyaluronidase. Then, HA fillers were reinjected sequentially with differing time intervals from 30 minutes to 14 days. 1 hour after the reinjection of the last HA filler, all injection sites were excised for histologic evaluation. 3 hours after reinjection of HA filler, the appearance of filler material became evident again, retaining its shape and volume. 6 hours after reinjection, the filler materials restored almost its original volume and there were no significant differences from the positive control. Our data suggest that the hyaluronidase loses its effect in dermis and subcutaneous tissue within 3-6 hours after the injection and successful engraftment of reinjected HA filler can be accomplished 6 hours after the injection.

Application of mixed based membrane technology from component materials bintaro, zeolite and bentonite to reduction of songket waste liquid cloth

NASA Astrophysics Data System (ADS)

Dahlan, Muhammad Hatta; Saleh, Abdullah; Asip, Faisol; Makmun, Akbar; Defi

2017-11-01

Application of membrane technology based on clay mixture, Activated Carbon from Bintaro, Zeolite and Bentonit to process the waste water of Songket cloth is Palembang traditionally cloth. The applied research is into the superior field of industrial and household waste processing with membrane ceramic technology. The objective of this research is to design the liquid waste separation tool of jumputan cloth using better and simpler ceramic membrane so that it can help the artisans of Palembang songket or songket in processing the waste in accordance with the standard of environmental quality standard (BML) and Pergub Sumsel no. 16 in 2005. The specific target to be achieved can decrease the waste of cloth jumputan in accordance with applicable environmental quality standards the method used in achieving the objectives of this study using 2 processes namely the adsorption process using activated carbon and the separation process using a ceramic membrane based on the composition of the mixture. The activated carbon from bintaro seeds is expected to decrease the concentration of liquid waste of Songket cloth. Bintaro seeds are non-edible fruits where the composition contains organic ingredients that can absorb because contains dyes and filler metals. The process of membranization in the processing is expected to decrease the concentration of waste better and clear water that can be used as recycled water for household use. With the composition of a mixture of clay-based materials: zeolite, bentonit, activated carbon from bintaro seeds are expected Find the solution and get the novelty value in the form of patent in this research

Welding wire pressure sensor assembly

NASA Technical Reports Server (NTRS)

Morris, Timothy B. (Inventor); Milly, Peter F., Sr. (Inventor); White, J. Kevin (Inventor)

1994-01-01

The present invention relates to a device which is used to monitor the position of a filler wire relative to a base material being welded as the filler wire is added to a welding pool. The device is applicable to automated welding systems wherein nonconsumable electrode arc welding processes are utilized in conjunction with a filler wire which is added to a weld pool created by the electrode arc. The invention senses pressure deviations from a predetermined pressure between the filler wire and the base material, and provides electrical signals responsive to the deviations for actuating control mechanisms in an automatic welding apparatus so as to minimize the pressure deviation and to prevent disengagement of the contact between the filler wire and the base material.

The disfluent discourse: Effects of filled pauses on recall

PubMed Central

Fraundorf, Scott H.; Watson, Duane G.

2011-01-01

We investigated the mechanisms by which fillers, such as uh and um, affect memory for discourse. Participants listened to and attempted to recall recorded passages adapted from Alice’s Adventures in Wonderland. The type and location of interruptions were manipulated through digital splicing. In Experiment 1, we tested a processing time account of fillers’ effects. While fillers facilitated recall, coughs matched in duration to the fillers impaired recall, suggesting that fillers’ benefits cannot be attributed to adding processing time. In Experiment 2, fillers’ locations were manipulated based on norming data to be either predictive or non-predictive of upcoming material. Fillers facilitated recall in both cases, inconsistent with an account in which listeners predict upcoming material using past experience with the distribution of fillers. Instead, these results suggest an attentional orienting account in which fillers direct attention to the speech stream but do not always result in specific predictions about upcoming material. PMID:21765590

Joint Workplan on Filler Investigations for DPCs.

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

Hardin, Ernest; Brady, Patrick Vane

2017-12-01

This workplan addresses filler attributes (i.e., possible requirements), assumptions needed for analysis, selection of filler materials, testing needs, and a long-range perspective on R&D activities leading to filler demonstration and a safety basis for implementation.

Burn-Resistant, Strong Metal-Matrix Composites

NASA Technical Reports Server (NTRS)

Stoltzfus, Joel M.; Tayal, Moti J.

2003-01-01

Ceramic particulate fillers increase the specific strengths and burn resistances of metals: This is the conclusion drawn by researchers at Johnson Space Center's White Sands Test Facility. The researchers had theorized that the inclusion of ceramic particles in metal tools and other metal objects used in oxygen-rich atmospheres (e.g., in hyperbaric chambers and spacecraft) could reduce the risk of fire and the consequent injury or death of personnel. In such atmospheres, metal objects act as ignition sources, creating fire hazards. However, not all metals are equally hazardous: some are more burn-resistant than others are. It was the researchers purpose to identify a burn-resistant, high-specific-strength ceramic-particle/metal-matrix composite that could be used in oxygen-rich atmospheres. The researchers studied several metals. Nickel and cobalt alloys exhibit high burn resistances and are dense. The researchers next turned to ceramics, which they knew do not act as ignition sources. Unlike metals, ceramics are naturally burn-resistant. Unfortunately, they also exhibit low fracture toughnesses.

Fabrication, Properties and Applications of Dense Hydroxyapatite: A Review

PubMed Central

Prakasam, Mythili; Locs, Janis; Salma-Ancane, Kristine; Loca, Dagnija; Largeteau, Alain; Berzina-Cimdina, Liga

2015-01-01

In the last five decades, there have been vast advances in the field of biomaterials, including ceramics, glasses, glass-ceramics and metal alloys. Dense and porous ceramics have been widely used for various biomedical applications. Current applications of bioceramics include bone grafts, spinal fusion, bone repairs, bone fillers, maxillofacial reconstruction, etc. Amongst the various calcium phosphate compositions, hydroxyapatite, which has a composition similar to human bone, has attracted wide interest. Much emphasis is given to tissue engineering, both in porous and dense ceramic forms. The current review focusses on the various applications of dense hydroxyapatite and other dense biomaterials on the aspects of transparency and the mechanical and electrical behavior. Prospective future applications, established along the aforesaid applications of hydroxyapatite, appear to be promising regarding bone bonding, advanced medical treatment methods, improvement of the mechanical strength of artificial bone grafts and better in vitro/in vivo methodologies to afford more particular outcomes. PMID:26703750

Sol-gel derived polymer composites for energy storage and conversion

NASA Astrophysics Data System (ADS)

Han, Kuo

Sol-gel process is a simple chemistry to convert the small precursor molecules into an inorganic polymer, which could be applied to synthesize inorganic materials, modify the interface of materials, bridge the organic and inorganic materials, etc. In this dissertation, novel sol-gel derived composites have been developed for high dielectric breakdown capacitors, low high frequency loss capacitors and flexible piezoelectrics. Numerous efforts have been made in the past decades to improve the energy storage capability of composite materials by incorporating nanometer scale ceramic addictives with high dielectric permittivity into dielectric polymers with high breakdown strength. However, most composites suffer from the low breakdown strength and make the potential gain in energy density small. Here, a new chemical strategy is proposed that, through sol-gel reactions between ceramic precursors and functional groups at the end of the functionalized Poly(vinylidene fluoride -co-chlorotrifluoroethylene) chains, amorphous low permittivity ceramics was in-situ generated in the polymer matrix and cross-linked the polymer chains simultaneously. By carefully tuning precursors, the polymer/precursors feeding ratios, a series of nanocomposites were systematically designed. All the samples are comprehensively characterized and the structure-property correlations are well investigated. The optimal samples exhibit higher breakdown strength than the pristine polymer. The enhanced breakdown strength ascribed to low contrast in permittivity, great dispersion and improved electrical and mechanical properties. This newly developed approach has shown great promise for new composite capacitors. The percolative polymer composites have recently exhibited great potential in energy storage due to their high dielectric permittivities at the neighborhood of the percolation threshold. Yet high energy dissipation and poor voltage endurance of the percolative composites resulted from electrical conduction are still open issues to be addressed before full potential can be realized. Herein we report the percolative composites based on ferroelectric poly(vinylidene fluoride-co-chlorotrifluoroethylene) as the matrix and sol-gel derived SiO2 coated reduced graphene oxide nanosheets as the filler. By capitalizing on the SiO2 surface layers which have high electrical resistivity and breakdown strength, the composites exhibit superior dielectric performance as compared to the respective composites containing bare reduced graphene oxide nanosheet fillers. In addition to greatly reduced dielectric loss, little change in dielectric loss has been observed within medium frequency range (ie. 300 KHz-3 MHz) in the prepared composites even with a filler concentration beyond the percolation threshold, indicating significantly suppressed energy dissipation and the feasibility of using the conductor-insulator composites beyond the percolation threshold. Moreover, remarkable breakdown strength of 80 MV/m at the percolation threshold has been achieved in the composite, which far exceeds those of conventional percolative composites (lower than 0.1 MV/m in most cases) and thus enables the applications of the percolative composites at high electric fields. This work offers a new avenue to the percolative polymer composites exhibiting high permittivity, reduced loss and excellent breakdown strength for electrical energy storage applications. Flexible piezoelectric materials have attracted extensive attention because they can provide a practical way to scavenge energy from the environment and motions. It also provides the possibility to fabricate wearable and self-powered energy generator for powering small electronic devices. In the dissertation a new composite including BTO 3D structure and PDMS has been successfully fabricated using the sol-gel process. The structure, flexibility, dielectric and piezoelectric properties have been well studied. The new material shows a high g33 value of more than 400 mV m/N. Moreover, the durability of this composite has been confirmed by cycle tests even though the BTO structure falls apart into small pieces in the PDMS matrix. The unique morphology of the composite allows the broken piece to connect with each other to generate power under stress. This work also opens a new route toward flexible piezoelectric composites.

Effects of Ion-Releasing Tooth-Coating Material on Demineralization of Bovine Tooth Enamel

PubMed Central

Kawasaki, Koji; Kambara, Masaki

2014-01-01

We compared the effect of a novel ion-releasing tooth-coating material that contained S-PRG (surface-reaction type prereacted glass-ionomer) filler to that of non-S-PRG filler and nail varnish on the demineralization of bovine enamel subsurface lesions. The demineralization process of bovine enamel was examined using quantitative light-induced fluorescence (QLF) and electron probe microanalyzer (EPMA) measurement. Ion concentrations in demineralizing solution were measured using inductively coupled plasma atomic (ICP) emission spectrometry and an ion electrode. The nail varnish group and the non-S-PRG filler group showed linear demineralization. Although the nail varnish group and the non-S-PRG filler group showed linear demineralization, the S-PRG filler group did not. Further, plane-scanning by EPMA analysis in the S-PRG filler group showed no changes in Ca ion distribution, and F ions showed peak levels on the surface of enamel specimens. Most ions in the demineralizing solution were present at higher concentrations in the S-PRG filler group than in the other two groups. In conclusion, only the S-PRG filler-containing tooth-coating material released ions and inhibited demineralization around the coating. PMID:24578706

Physical properties and depth of cure of a new short fiber reinforced composite.

PubMed

Garoushi, Sufyan; Säilynoja, Eija; Vallittu, Pekka K; Lassila, Lippo

2013-08-01

To determine the physical properties and curing depth of a new short fiber composite intended for posterior large restorations (everX Posterior) in comparison to different commercial posterior composites (Alert, TetricEvoCeram Bulk Fill, Voco X-tra base, SDR, Venus Bulk Fill, SonicFill, Filtek Bulk Fill, Filtek Superme, and Filtek Z250). In addition, length of fiber fillers of composite XENIUS base compared to the previously introduced composite Alert has been measured. The following properties were examined according to ISO standard 4049: flexural strength, flexural modulus, fracture toughness, polymerization shrinkage and depth of cure. The mean and standard deviation were determined and all results were statistically analyzed with analysis of variance ANOVA (a=0.05). XENIUS base composite exhibited the highest fracture toughness (4.6MPam(1/2)) and flexural strength (124.3MPa) values and the lower shrinkage strain (0.17%) among the materials tested. Alert composite revealed the highest flexural modulus value (9.9GPa), which was not significantly different from XENIUS base composite (9.5GPa). Depth of cure of XENIUS base (4.6mm) was similar than those of bulk fill composites and higher than other hybrid composites. The length of fiber fillers in XENIUS base was longer (1.3-2mm) than in Alert (20-60μm). The new short fiber composite differed significantly in its physical properties compared to other materials tested. This suggests that the latter could be used in high-stress bearing areas. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Long-term performance of thermoplastic composite material with cotton burr and stem (CBS) as a partial filler

USDA-ARS?s Scientific Manuscript database

Rationale: Cotton burr and stem (CBS) fraction of cotton gin byproducts has shown promise as a fiber filler in thermoplastic composites, with physical and mechanical properties comparable to that made with wood fiber fillers. However, the long-term performance of this composite material is not known...

Effect of Silver-Emitting Filler on Antimicrobial and Mechanical Properties of Soft Denture Lining Material

PubMed Central

Jabłońska-Stencel, Ewa; Pakieła, Wojciech; Mertas, Anna; Bobela, Elżbieta; Kasperski, Jacek; Chladek, Grzegorz

2018-01-01

Colonization of silicone-based soft lining materials by pathogenic yeast-type fungi is a common problem associated with the use of dentures. In this study, silver sodium hydrogen zirconium phosphate (SSHZP) was introduced into polydimethylsiloxane-based material as an antimicrobial filler at concentrations of 0.25, 0.5, 1, 2, 4, 6, 8, 10, 12, and 14% (w/w). The in vitro antimicrobial efficacy was investigated. Candida albicans was used as a characteristic representative of pathogenic oral microflora. Staphylococcus aureus and Escherichia coli were used as the typical Gram-positive and Gram-negative bacterial strains, respectively. The effect of filler addition on the Shore A hardness, tensile strength, tensile bond strength, sorption, and solubility was investigated. An increase in the filler concentration resulted in an increase in hardness, sorption, and solubility, and for the highest concentration, a decrease in bond strength. The favorable combination of antimicrobial efficacy with other properties was achieved at filler concentrations ranging from 2% to 10%. These composites exhibited mechanical properties similar to the material without the antimicrobial filler and enhanced in vitro antimicrobial efficiency. PMID:29470441

Recommendations for Filler Material Composition and Delivery Method for Bench-Scale Testing

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

Hardin, Ernest; Brady, Patrick Vane

This report supplements Joint Workplan on Filler Investigations for DPCs (SNL 2017) providing new and some corrected information for use in planning Phase 1 laboratory testing of slurry cements as possible DPC fillers. The scope description is to "Describe a complete laboratory testing program for filler composition, delivery, emplacement in surrogate canisters, and post-test examination. To the extent possible specify filler material and equipment sources." This report includes results from an independent expert review (Dr. Arun Wagh, retired from Argonne National Laboratory and contracted by Sandia) that helped to narrow the range of cement types for consideration, and to providemore » further guidance on mix variations to optimize injectability, durability, and other aspects of filler performance.« less

Friction stir welding and processing of oxide dispersion strengthened (ODS) alloys

DOEpatents

Ren, Weiju

2014-11-11

A method of welding including forming a filler material of a first oxide dispersoid metal, the first oxide dispersoid material having first strengthening particles that compensate for decreases in weld strength of friction stir welded oxide dispersoid metals; positioning the filler material between a first metal structure and a second metal structure each being comprised of at least a second oxide dispersoid metal; and friction welding the filler material, the first metal structure and the second metal structure to provide a weld.

Effects of age condition on the distribution and integrity of inorganic fillers in dental resin composites.

PubMed

D'Alpino, Paulo Henrique Perlatti; Svizero, Nádia da Rocha; Bim Júnior, Odair; Valduga, Claudete Justina; Graeff, Carlos Frederico de Oliveira; Sauro, Salvatore

2016-06-01

The aim of this study is to evaluate the distribution of the filler size along with the zeta potential, and the integrity of silane-bonded filler surface in different types of restorative dental composites as a function of the material age condition. Filtek P60 (hybrid composite), Filtek Z250 (small-particle filled composite), Filtek Z350XT (nanofilled composite), and Filtek Silorane (silorane composite) (3M ESPE) were tested at different stage condition (i.e., fresh/new, aged, and expired). Composites were submitted to an accelerated aging protocol (Arrhenius model). Specimens were obtained by first diluting each composite specimen in ethanol and then dispersed in potassium chloride solution (0.001 mol%). Composite fillers were characterized for their zeta potential, mean particle size, size distribution, via poly-dispersion dynamic light scattering. The integrity of the silane-bonded surface of the fillers was characterized by FTIR. The material age influenced significantly the outcomes; Zeta potential, filler characteristics, and silane integrity varied both after aging and expiration. Silorane presented the broadest filler distribution and lowest zeta potential. Nanofilled and silorane composites exhibited decreased peak intensities in the FTIR analysis, indicating a deficiency of the silane integrity after aging or expiry time. Regardless to the material condition, the hybrid and the small-particle-filled composites were more stable overtime as no significant alteration in filler size distribution, diameter, and zeta potential occurred. A deficiency in the silane integrity in the nanofilled and silorane composites seems to be affected by the material stage condition. The materials conditions tested in this study influenced the filler size distribution, the zeta potential, and integrity of the silane adsorbed on fillers in the nanofilled and silorane composites. Thus, this may result in a decrease of the clinical performance of aforementioned composites, in particular, if these are used after inappropriate storage conditions.

Influence of reactive fillers on concrete corrosion resistance

NASA Astrophysics Data System (ADS)

Rakhimbayev, Sh M.; Tolypina, N. M.; Khakhaleva, E. N.

2018-03-01

Contact surfaces represent the weakest link in a conglomerate structure of materials. They ensure the diffusion of aggressive agents inside the material. To reduce the conductivity of contact surfaces it is advisable to use reactive fillers, which interact with cement matrix via certain mechanisms, which in turn, reduces the permeability of the contact layer and fosters durability of products. The interaction of reactive fillers with calcium hydroxide of a concrete liquid phase in a contact area leads to the formation of hydrated calcium silicates of a tobermorite group. Such compounds, being settled in pores and capillaries of a product, colmatage and clog them to some extent thus leading to diffusion delay (inhibition) with regard to aggressive components of external media inside porous material, which in turn inhibits the corrosion rate. The authors studied and compared the corrosion of cement concrete with a standard filler (quartz sand) and a reactive filler (perlite and urtit). The experiments confirmed the positive influence of active fillers on concrete corrosion resistance.

Translucency of human teeth and dental restorative materials and its clinical relevance

NASA Astrophysics Data System (ADS)

Lee, Yong-Keun

2015-04-01

The purpose was to review the translucency of human teeth and related dental materials that should be considered for the development of esthetic restorative materials. Translucency is the relative amount of light transmission or diffuse reflection from a substrate surface through a turbid medium. Translucency influences the masking ability, color blending effect, and the degree of light curing through these materials. Regarding the translucency indices, transmission coefficient, translucency parameter, and contrast ratio have been used, and correlations among these indices were confirmed. Translucency of human enamel and dentine increases in direct proportion to the wavelength of incident light in the visible light range. As for the translucency changes by aging, limited differences were reported in human dentine, while those for enamel proved to increase. There have been studies for the adjustment of translucency in dental esthetic restorative materials; the size and amount of filler and the kind of resin matrix were modified in resin composites, and the kind of ingredient and the degree of crystallization were modified in ceramics. Based on the translucency properties of human enamel and dentine, those of replacing restorative materials should be optimized for successful esthetic rehabilitation. Biomimetic simulation of the natural tooth microstructure might be a promising method.

Ductility dip cracking susceptibility of Inconel Filler Metal 52 and Inconel Alloy 690

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

Kikel, J.M.; Parker, D.M.

1998-06-01

Alloy 690 and Filler Metal 52 have become the materials of choice for commercial nuclear steam generator applications in recent years. Filler Metal 52 exhibits improved resistance to weld solidification and weld-metal liquation cracking as compared to other nickel-based filler metals. However, recently published work indicates that Filler Metal 52 is susceptible to ductility dip cracking (DDC) in highly restrained applications. Susceptibility to fusion zone DDC was evaluated using the transverse varestraint test method, while heat affected zone (HAZ) DDC susceptibility was evaluated using a newly developed spot-on-spot varestraint test method. Alloy 690 and Filler Metal 52 cracking susceptibility wasmore » compared to the DDC susceptibility of Alloy 600, Filler Metal 52, and Filler Metal 625. In addition, the effect of grain size and orientation on cracking susceptibility was also included in this study. Alloy 690, Filler Metal 82, Filler Metal 52, and Filler Metal 625 were found more susceptible to fusion zone DDC than Alloy 600. Filler Metal 52 and Alloy 690 were found more susceptible to HAZ DDC when compared to wrought Alloy 600, Filler Metal 82 and Filler Metal 625. Filler Metal 52 exhibited the greatest susceptibility to HAZ DDC of all the weld metals evaluated. The base materials were found much more resistant to HAZ DDC in the wrought condition than when autogenously welded. A smaller grain size was found to offer greater resistance to DDC. For weld metal where grain size is difficult to control, a change in grain orientation was found to improve resistance to DDC.« less

Dielectric and Electromechanical Properties of Polyurethane and Polydimethylsiloxane Blends and their Nanocomposites

NASA Astrophysics Data System (ADS)

Cakmak, Enes

Conventional means of converting electrical energy to mechanical work are generally considered too noisy and bulky for many contemporary technologies such as microrobotic, microfluidic, and haptic devices. Dielectric electroactive polymers (D-EAPs) constitude a growing class of electroactive polymers (EAP) that are capable of producing mechanica work induced by an applied electric field. D-EAPs are considered remarkably efficient and well suited for a wide range of applications, including ocean-wave energy harvesters and prosthetic devices. However, the real-world application of D-EAPs is very limited due to a number of factors, one of which is the difficulty of producing high actuation strains at acceptably low electric fields. D-EAPs are elastomeric polymers and produce large strain response induced by external electric field. The electromechanical properties of D-EAPs depend on the dielectric properties and mechanical properties of the D-EAP. In terms of dielectric behavior, these actuators require a high dielectric constant, low dielectric loss, and high dielectric strength to produce an improved actuation response. In addition to their dielectric properties, the mechanical properties of D-EAPs, such as elastic moduli and hysteresis, are also of importance. Therefore, material properties are a key feature of D-EAP technology. DE actuator materials reported in the literature cover many types of elastomers and their composites formed with dielectric fillers. Along with polymeric matrix materials, various ceramic, metal, and organic fillers have been employed in enhancing dielectric behavior of DEs. This work describes an effort to characterize elastomer blends and composites of different matrix and dielectric polymer fillers according to their dielectric, mechanical, and electromechanical responses. This dissertation focuses on the development and characterization of polymer-polymer blends and composites from a high-k polyurethane (PU) and polydimethylsiloxane (PDMS) elastomers. Two different routes were followed with respect to elastomer processing: The first is a simple solution blending of the two types of elastomers, and the second is based on preparation of composites from PU nanofiber webs and PDMS elastomer. Both the blends and the nanofiber web composites showed improved dielectric and actuation characteristics.

Piezoresistivity, mechanisms and model of cement-based materials with CNT/NCB composite fillers

NASA Astrophysics Data System (ADS)

Zhang, Liqing; Ding, Siqi; Dong, Sufen; Li, Zhen; Ouyang, Jian; Yu, Xun; Han, Baoguo

2017-12-01

The use of conductive cement-based materials as sensors has attracted intense interest over past decades. In this paper, carbon nanotube (CNT)/nano carbon black (NCB) composite fillers made by electrostatic self-assembly are used to fabricate conductive cement-based materials. Electrical and piezoresistive properties of the fabricated cement-based materials are investigated. Effect of filler content, load amplitudes and rate on piezoresistive property within elastic regime and piezoresistive behaviors during compressive loading to destruction are explored. Finally, a model describing piezoresistive property of cement-based materials with CNT/NCB composite fillers is established based on the effective conductive path and tunneling effect theory. The research results demonstrate that filler content and load amplitudes have obvious effect on piezoresistive property of the composites materials, while load rate has little influence on piezoresistive property. During compressive loading to destruction, the composites also show sensitive piezoresistive property. Therefore, the cement-based composites can be used to monitor the health state of structures during their whole life. The built model can well describe the piezoresistive property of the composites during compressive loading to destruction. The good match between the model and experiment data indicates that tunneling effect actually contributes to piezoresistive phenomenon.

Filler bar heating due to stepped tiles in the shuttle orbiter thermal protection system

NASA Technical Reports Server (NTRS)

Petley, D. H.; Smith, D. M.; Edwards, C. L. W.; Patten, A. B.; Hamilton, H. H., II

1983-01-01

An analytical study was performed to investigate the excessive heating in the tile to tile gaps of the Shuttle Orbiter Thermal Protection System due to stepped tiles. The excessive heating was evidence by visible discoloration and charring of the filler bar and strain isolation pad that is used in the attachment of tiles to the aluminum substrate. Two tile locations on the Shuttle orbiter were considered, one on the lower surface of the fuselage and one on the lower surface of the wing. The gap heating analysis involved the calculation of external and internal gas pressures and temperatures, internal mass flow rates, and the transient thermal response of the thermal protection system. The results of the analysis are presented for the fuselage and wing location for several step heights. The results of a study to determine the effectiveness of a half height ceramic fiber gap filler in preventing hot gas flow in the tile gaps are also presented.

Matrices of radiation-protective composites using bismuth oxide

NASA Astrophysics Data System (ADS)

Yashkina, S. Yu; Doroganov, V. A.; Trepalina, Yu N.; Loktionov, V. A.; Evtushenko, E. I.

2018-03-01

The article presents the results of investigations of radiation-protective composites with two types of matrices based on chamotte and aluminous binders. The synthesis of binders was carried out according to the principles of the production of ceramic concrete based on the artificial ceramic binders (ACB). Bismuth oxide was selected as filler. Basic physical and mechanical, as well as radiation-protective characteristics, of composites with different ratios of ACB and Bi2O3 were shown. It was found out that binder of high-alumina chamotte can be used as an optimal matrix base. Composites on its basis have higher structural and radiation-protective properties.

Deposition and thermal characterization of nano-structured aluminum nitride thin film on Cu-W substrate for high power light emitting diode package.

PubMed

Cho, Hyun Min; Kim, Min-Sun

2014-08-01

In this study, we developed AlN thick film on metal substrate for hybrid type LED package such as chip on board (COB) using metal printed circuit board (PCB). Conventional metal PCB uses ceramic-polymer composite as electrical insulating layer. Thermal conductivities of such type dielectric film are typically in the range of 1~4 W/m · K depending on the ceramic filler. Also, Al or Cu alloy are mainly used for metal base for high thermal conduction to dissipate heat from thermal source mounted on metal PCB. Here we used Cu-W alloy with low thermal expansion coefficient as metal substrate to reduce thermal stress between insulating layer and base metal. AlN with polyimide (PI) powder were used as starting materials for deposition. We could obtain very high thermal conductivity of 28.3 W/m · K from deposited AlN-PI thin film by AlN-3 wt% PI powder. We made hybrid type high power LED package using AlN-PI thin film. We tested thermal performance of this film by thermal transient measurement and compared with conventional metal PCB substrate.

Ball clay

USGS Publications Warehouse

Virta, R.L.

2011-01-01

The article discusses the latest developments in the global ball clay mining industry, particularly in the U.S., as of June 2011. It cites several firms that are involved in ball clay mining in the U.S., including HC Spins Clay Co. Inc., the Imerys Group and Old Hickory Clay Co. Among the products made from ball clay are ceramic tiles, sanitaryware, as well as fillers, extenders and binders.

Method and apparatus for the management of hazardous waste material

DOEpatents

Murray, Jr., Holt

1995-01-01

A container for storing hazardous waste material, particularly radioactive waste material, consists of a cylindrical body and lid of precipitation hardened C17510 beryllium-copper alloy, and a channel formed between the mated lid and body for receiving weld filler material of C17200 copper-beryllium alloy. The weld filler material has a precipitation hardening temperature lower than the aging kinetic temperature of the material of the body and lid, whereby the weld filler material is post weld heat treated for obtaining a weld having substantially the same physical, thermal, and electrical characteristics as the material of the body and lid. A mechanical seal assembly is located between an interior shoulder of the body and the bottom of the lid for providing a vacuum seal.

Polymer Composite and Nanocomposite Dielectric Materials for Pulse Power Energy Storage †

PubMed Central

Barber, Peter; Balasubramanian, Shiva; Anguchamy, Yogesh; Gong, Shushan; Wibowo, Arief; Gao, Hongsheng; Ploehn, Harry J.; zur Loye, Hans-Conrad

2009-01-01

This review summarizes the current state of polymer composites used as dielectric materials for energy storage. The particular focus is on materials: polymers serving as the matrix, inorganic fillers used to increase the effective dielectric constant, and various recent investigations of functionalization of metal oxide fillers to improve compatibility with polymers. We review the recent literature focused on the dielectric characterization of composites, specifically the measurement of dielectric permittivity and breakdown field strength. Special attention is given to the analysis of the energy density of polymer composite materials and how the functionalization of the inorganic filler affects the energy density of polymer composite dielectric materials.

Evaluation of zirconia, thoria and zirconium diboride for advanced resistojet use

NASA Technical Reports Server (NTRS)

Page, R. J.; Short, R. A.; Halbach, C. R.

1972-01-01

A literature survey was conducted to collect material properties data on all advanced high temperature materials. Three of these, Y2O3-stabilized ZrO2, ThO2, and ZrB2 with additives of C and SiC were selected for further study. Stabilized ZrO2 and ThO2 were found to have higher temperature oxidation resistance than any metal and great potential for use in advanced biowaste resistojets. ZrO2 has a lower electrical resistivity and sublimation and a higher creep endurance strength. ZrO2 and ThO2 tubular heat exchangers, electrically heated indirectly, were evaluated in short tests to about 1900 K in flowing CO2. ZrO2 was subjected to N2, H2, H2O and vacuum as well. X-ray diffraction and fluorescence analyses were made. The metal-to-ceramic seal technology for ZrO2 and ThO2 was developed using chemical vapor deposition of tantalum for metallizing and 82 Au - 18 Ni filler braze.

Ni-coated CaCu3Ti4O12/low density polyethylene composite material with ultra-high dielectric permittivity

NASA Astrophysics Data System (ADS)

Gao, L.; Wang, X.; Chen, Y.; Chi, Q. G.; Lei, Q. Q.

2015-08-01

We report a novel low-density polyethylene (LDPE) composite filled with nickel-coated CaCu3Ti4O12 ceramic (denoted as CCTO@Ni), prepared by a melt mixing technique, and its prominent dielectric characteristics. The effects of magnetic field treatment on the dielectric properties of CCTO@Ni/LDPE composite films with a low filler concentration of 10 vol.% were investigated. Our results show that the dielectric permittivity, loss tangent, and conductivity of the LDPE composite films initially improved and then decreased with increasing treatment time under the applied magnetic field. Magnetic field treatment for 60 min led to an ultra-high dielectric permittivity value of 1.57 × 104, four orders of magnitude higher than that of the pure LDPE material. Our results indicate that the magnetic treatment may have induced a percolation effect and enhanced the interfacial polarization of the CCTO@Ni/LDPE composite, resulting in the observed changes in its dielectric properties.

Nanoscale hydroxyapatite particles for bone tissue engineering.

PubMed

Zhou, Hongjian; Lee, Jaebeom

2011-07-01

Hydroxyapatite (HAp) exhibits excellent biocompatibility with soft tissues such as skin, muscle and gums, making it an ideal candidate for orthopedic and dental implants or components of implants. Synthetic HAp has been widely used in repair of hard tissues, and common uses include bone repair, bone augmentation, as well as coating of implants or acting as fillers in bone or teeth. However, the low mechanical strength of normal HAp ceramics generally restricts its use to low load-bearing applications. Recent advancements in nanoscience and nanotechnology have reignited investigation of nanoscale HAp formation in order to clearly define the small-scale properties of HAp. It has been suggested that nano-HAp may be an ideal biomaterial due to its good biocompatibility and bone integration ability. HAp biomedical material development has benefited significantly from advancements in nanotechnology. This feature article looks afresh at nano-HAp particles, highlighting the importance of size, crystal morphology control, and composites with other inorganic particles for biomedical material development. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

PMMA denture base material enhancement: a review of fiber, filler, and nanofiller addition

PubMed Central

Gad, Mohammed M; Fouda, Shaimaa M; Al-Harbi, Fahad A; Näpänkangas, Ritva; Raustia, Aune

2017-01-01

This paper reviews acrylic denture base resin enhancement during the past few decades. Specific attention is given to the effect of fiber, filler, and nanofiller addition on poly(methyl methacrylate) (PMMA) properties. The review is based on scientific reviews, papers, and abstracts, as well as studies concerning the effect of additives, fibers, fillers, and reinforcement materials on PMMA, published between 1974 and 2016. Many studies have reported improvement of PMMA denture base material with the addition of fillers, fibers, nanofiller, and hybrid reinforcement. However, most of the studies were limited to in vitro investigations without bioactivity and clinical implications. Considering the findings of the review, there is no ideal denture base material, but the properties of PMMA could be improved with some modifications, especially with silanized nanoparticle addition and a hybrid reinforcement system. PMID:28553115

Injectable fillers: review of material and properties.

PubMed

Attenello, Natalie Huang; Maas, Corey S

2015-02-01

With an increasing understanding of the aging process and the rapidly growing interest in minimally invasive treatments, injectable facial fillers have changed the perspective for the treatment and rejuvenation of the aging face. Other than autologous fat and certain preformed implants, the collagen family products were the only Food and Drug Administration approved soft tissue fillers. But the overwhelming interest in soft tissue fillers had led to the increase in research and development of other products including bioengineered nonpermanent implants and permanent alloplastic implants. As multiple injectable soft tissue fillers and biostimulators are continuously becoming available, it is important to understand the biophysical properties inherent in each, as these constitute the clinical characteristics of the product. This article will review the materials and properties of the currently available soft tissue fillers: hyaluronic acid, calcium hydroxylapatite, poly-l-lactic acid, polymethylmethacrylate, and autologous fat (and aspirated tissue including stem cells). Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

46 CFR 56.70-5 - Material.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Material. 56.70-5 Section 56.70-5 Shipping COAST GUARD..., Assembly and Erection § 56.70-5 Material. (a) Filler metal. All filler metal, including consumable insert material, must comply with the requirements of section IX of the ASME Boiler and Pressure Vessel Code...

46 CFR 56.70-5 - Material.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Material. 56.70-5 Section 56.70-5 Shipping COAST GUARD..., Assembly and Erection § 56.70-5 Material. (a) Filler metal. All filler metal, including consumable insert material, must comply with the requirements of section IX of the ASME Boiler and Pressure Vessel Code...

46 CFR 56.70-5 - Material.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Material. 56.70-5 Section 56.70-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Fabrication, Assembly and Erection § 56.70-5 Material. (a) Filler metal. All filler metal, including consumable insert material, must comply with the...

46 CFR 56.70-5 - Material.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Material. 56.70-5 Section 56.70-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Fabrication, Assembly and Erection § 56.70-5 Material. (a) Filler metal. All filler metal, including consumable insert material, must comply with the...

Investigation on Using SBS and Active Carbon Filler to Reduce the VOC Emission from Bituminous Materials.

PubMed

Cui, Peiqiang; Wu, Shaopeng; Li, Fuzhou; Xiao, Yue; Zhang, Honghua

2014-08-26

Bituminous materials are playing a vital role in pavement design and the roofing industry because of outstanding properties. Unfortunately, bituminous materials will release volatile organic compounds (VOC), making them non-environmentally friendly. Therefore, technologies that can be used to decrease the VOC emission are urgently required. In this research, the VOC emission and material behaviors were analyzed and compared to investigate the possibility of adding styrene butadiene styrene (SBS) and active carbon filler into bituminous materials to develop environmentally-friendly materials. Thermal gravimetric analysis-mass spectrometry (TG-MS) and ultraviolet-visible spectroscopy testing (UV-Vis) were employed to characterize the VOC emission process. Temperature sweep testing and frequency sweep testing were conducted to evaluate the rheological properties of bituminous materials. Research results indicated that the combined introduction of 4 wt% styrene butadiene styrene (SBS) and 4 wt% active carbon filler cannot only significantly lower the VOC emission speed and amount, but also improve the deformation resistance behavior at a higher temperature. SBS and active carbon filler can be used to reduce the VOC emission form bituminous materials.

Investigation on Using SBS and Active Carbon Filler to Reduce the VOC Emission from Bituminous Materials

PubMed Central

Cui, Peiqiang; Wu, Shaopeng; Li, Fuzhou; Xiao, Yue; Zhang, Honghua

2014-01-01

Bituminous materials are playing a vital role in pavement design and the roofing industry because of outstanding properties. Unfortunately, bituminous materials will release volatile organic compounds (VOC), making them non-environmentally friendly. Therefore, technologies that can be used to decrease the VOC emission are urgently required. In this research, the VOC emission and material behaviors were analyzed and compared to investigate the possibility of adding styrene butadiene styrene (SBS) and active carbon filler into bituminous materials to develop environmentally-friendly materials. Thermal gravimetric analysis-mass spectrometry (TG-MS) and ultraviolet-visible spectroscopy testing (UV-Vis) were employed to characterize the VOC emission process. Temperature sweep testing and frequency sweep testing were conducted to evaluate the rheological properties of bituminous materials. Research results indicated that the combined introduction of 4 wt% styrene butadiene styrene (SBS) and 4 wt% active carbon filler cannot only significantly lower the VOC emission speed and amount, but also improve the deformation resistance behavior at a higher temperature. SBS and active carbon filler can be used to reduce the VOC emission form bituminous materials. PMID:28788181

High Temperature Stable Separator for Lithium Batteries Based on SiO2 and Hydroxypropyl Guar Gum

PubMed Central

Carvalho, Diogo Vieira; Loeffler, Nicholas; Kim, Guk-Tae; Passerini, Stefano

2015-01-01

A novel membrane based on silicon dioxide (SiO2) and hydroxypropyl guar gum (HPG) as binder is presented and tested as a separator for lithium-ion batteries. The separator is made with renewable and low cost materials and an environmentally friendly manufacturing processing using only water as solvent. The separator offers superior wettability and high electrolyte uptake due to the optimized porosity and the good affinity of SiO2 and guar gum microstructure towards organic liquid electrolytes. Additionally, the separator shows high thermal stability and no dimensional-shrinkage at high temperatures due to the use of the ceramic filler and the thermally stable natural polymer. The electrochemical tests show the good electrochemical stability of the separator in a wide range of potential, as well as its outstanding cycle performance. PMID:26512701

The Effect of Palladium Additions on the Solidus/Liquidus Temperatures and Wetting Properties of Ag-CuO Based Air Brazes

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

Darsell, Jens T.; Weil, K. Scott

2007-05-16

As a means of increasing the use temperature of ceramic-ceramic and ceramic-metal air brazes, palladium was investigated as possible ternary addition to the currently employed silver - copper oxide system. The silver component was directly substituted with palladium to form the following series of alloys: (100-y)[(100-z)Pd - (z)Ag] - (y)CuOx where y = 0 - 34 mol% CuOx, z = 50 - 100 mol% silver, and x = 0, 0.5, and 1, denoting copper metal, Cu2O, or CuO. From differential scanning calorimetry, it was determined that the addition of palladium causes an increase in the solidus and liquidus temperatures ofmore » the resulting Pd-Ag-CuO brazes. In general, the liquidus was found to increase by approximately 220°C for the (100-y)(25Pd - 75Ag) - (z)CuOx filler metal compositions relative to comparable Ag-CuOx alloys. Likewise, the solidus was found to increase for these alloys, respectively by 185°C and 60°C, respectively for CuOx contents of y = 0 - 1mol% and 4 - 10 mol%. For the (100-y)(50Pd - 50Ag) - (y)CuOx alloys, the solidus increased between 280 - 390°C over a copper oxide compositional range of x = 0 to 8 mol%. It was determined from sessile drop experiments conducted on alumina substrates that in all cases the palladium causes an increase in the wetting angle relative to the corresponding binary braze. Alloy compositions of (100-y)(25Pd - 75Ag) - (y)CuOx displayed increased wetting angles of 5-20° relative to comparable binary compositions. (100-y)(50Pd - 50Ag) - (y)CuOx alloys exhibited an increase in contact angle of 10-60° and compositions containing less than 10 mol% CuOx were not able to wet the substrate. Scanning electron microscopy indicated that the microstructure of the braze consists of discrete CuOx precipitates in an alloyed silver-palladium matrix. In both the binary and ternary filler metal formulations, a reaction layer consisting of CuAlO2 was observed along the interface with the alumina substrate. This reaction product appears to be beneficial in promoting wetting by the remaining braze filler metal. However the formation of this layer is hindered as the concentration of palladium in the filler metal is increased, which appears to be the primary cause of poor wettability in these compositions, as indicated by the substantial amount of porosity found along the braze/substrate interface.« less

Method and apparatus for the management of hazardous waste material

DOEpatents

Murray, H. Jr.

1995-02-21

A container for storing hazardous waste material, particularly radioactive waste material, consists of a cylindrical body and lid of precipitation hardened C17510 beryllium-copper alloy, and a channel formed between the mated lid and body for receiving weld filler material of C17200 copper-beryllium alloy. The weld filler material has a precipitation hardening temperature lower than the aging kinetic temperature of the material of the body and lid, whereby the weld filler material is post weld heat treated for obtaining a weld having substantially the same physical, thermal, and electrical characteristics as the material of the body and lid. A mechanical seal assembly is located between an interior shoulder of the body and the bottom of the lid for providing a vacuum seal. 40 figs.

Polymer Layered Silicate Nanocomposites: A Review

PubMed Central

Mittal, Vikas

2009-01-01

This review aims to present recent advances in the synthesis and structure characterization as well as the properties of polymer layered silicate nanocomposites. The advent of polymer layered silicate nanocomposites has revolutionized research into polymer composite materials. Nanocomposites are organic-inorganic hybrid materials in which at least one dimension of the filler is less than 100 nm. A number of synthesis routes have been developed in the recent years to prepare these materials, which include intercalation of polymers or pre-polymers from solution, in-situ polymerization, melt intercalation etc. The nanocomposites where the filler platelets can be dispersed in the polymer at the nanometer scale owing to the specific filler surface modifications, exhibit significant improvement in the composite properties, which include enhanced mechanical strength, gas barrier, thermal stability, flame retardancy etc. Only a small amount of filler is generally required for the enhancement in the properties, which helps the composite materials retain transparency and low density.

Composite bone cements loaded with a bioactive and ferrimagnetic glass-ceramic: Leaching, bioactivity and cytocompatibility.

PubMed

Verné, Enrica; Bruno, Matteo; Miola, Marta; Maina, Giovanni; Bianco, Carlotta; Cochis, Andrea; Rimondini, Lia

2015-08-01

In this work, composite bone cements, based on a commercial polymethylmethacrylate matrix (Palamed®) loaded with ferrimagnetic bioactive glass-ceramic particles (SC45), were produced and characterized in vitro. The ferrimagnetic bioactive glass-ceramic belongs to the system SiO2-Na2O-CaO-P2O5-FeO-Fe2O3 and contains magnetite (Fe3O4) crystals into a residual amorphous bioactive phase. Three different formulations (containing 10, 15 and 20 wt.% of glass-ceramic particles respectively) have been investigated. These materials are intended to be applied as bone fillers for the hyperthermic treatment of bone tumors. The morphological, compositional, calorimetric and mechanical properties of each formulation have been already discussed in a previous paper. The in vitro properties of the composite bone cements described in the present paper are related to iron ion leaching test (by graphite furnace atomic absorption spectrometer), bioactivity (i.e. the ability to stimulate the formation of a hydroxyapatite - HAp - layer on their surface after soaking in simulated body fluid SBF) and cytocompatibility toward human osteosarcoma cells (ATCC CRL-1427, Mg63). Morphological and chemical characterizations by scanning electron microscopy and energy dispersion spectrometry have been performed on the composite samples after each test. The iron release was negligible and all the tested samples showed the growth of HAp on their surface after 28 days of immersion in a simulated body fluid (SBF). Cells showed good viability, morphology, adhesion, density and the ability to develop bridge-like structures on all investigated samples. A synergistic effect between bioactivity and cell mineralization was also evidenced. Copyright © 2015 Elsevier B.V. All rights reserved.

Directionally solidified article with weld repair

NASA Technical Reports Server (NTRS)

Smashey, Russell W. (Inventor); Snyder, John H. (Inventor); Borne, Bruce L. (Inventor)

2003-01-01

A directionally solidified nickel-base superalloy article has a defect therein extending parallel to the solidification direction. The article is repaired by removing any foreign matter present in the defect, and then heating the article to a repair temperature of from about 60 to about 98 percent of the solidus temperature of the base material in a chamber containing a protective gas that inhibits oxidation of the base material. The defect is filled with a filler metal while maintaining the article at the repair temperature. The filling is accomplished by providing a source of the filler metal of substantially the same composition as the base material of the directionally solidified article, and melting the filler metal into the defect progressively while moving the source of the filler metal relative to the article in a direction parallel to the solidification direction. Optionally, additional artificial heat extraction is accomplished in a heat-flow direction that is within about 45 degrees of the solidification direction, as the filler metal solidifies within the defect. The article may thereafter be heat treated.

Weld repair of directionally solidified articles

NASA Technical Reports Server (NTRS)

Smashey, Russell W. (Inventor); Snyder, John H. (Inventor); Borne, Bruce L. (Inventor)

2002-01-01

A directionally solidified nickel-base superalloy article has a defect therein extending parallel to the solidification direction. The article is repaired by removing any foreign matter present in the defect, and then heating the article to a repair temperature of from about 60 to about 98 percent of the solidus temperature of the base material in a chamber containing a protective gas that inhibits oxidation of the base material. The defect is filled with a filler metal while maintaining the article at the repair temperature. The filling is accomplished by providing a source of the filler metal of substantially the same composition as the base material of the directionally solidified article, and melting the filler metal into the defect progressively while moving the source of the filler metal relative to the article in a direction parallel to the solidification direction. Optionally, additional artificial heat extraction is accomplished in a heat-flow direction that is within about 45 degrees of the solidification direction, as the filler metal solidifies within the defect. The article may thereafter be heat treated.

Ultramafic-Hosted Talc-Magnesite Deposits

USGS Publications Warehouse

Robinson, Gilpin R.; Van Gosen, Bradley S.; Foley, Nora K.

2006-01-01

This presentation on the geology of ultramafic-hosted talc-magnesite deposits was given at the 42nd Forum on the Geology of Industrial Minerals, May 7-13, 2006, in Asheville, North Carolina (USA). Talc is a soft inert industrial mineral commodity commonly used as a component or filler in ceramic, paint, paper, plastic, roofing, and electrical applications. Ultramafic-hosted talc-magnesite deposits are important sources of talc.

Characteristics comparison of weld metal zones welded to cast and forged steels for piston crown material

NASA Astrophysics Data System (ADS)

Moon, Kyung-Man; Kim, Yun-Hae; Lee, Myeong-Hoon; Baek, Tae-Sil

2015-03-01

An optimum repair welding for the piston crown which is one of the engine parts exposed to the combustion chamber is considered to be very important to prolong the engine lifetime from an economical point of view. In this study, two types of filler metals such as 1.25Cr-0.5Mo, 0.5Mo were welded with SMAW method and the other two types of filler metals such as Inconel 625 and 718 were welded with GTAW method, respectively, and the used base metals were the cast and forged steels of the piston crown material. The weld metal zones welded with Inconel 625 and 718 filler metals exhibited higher corrosion resistance compared to 1.25Cr-0.5Mo and 0.5Mo filler metals. In particular, the weld metal zone welded with Inconel 718 and 0.5Mo, filler metals indicated the best and worst corrosion resistance, respectively. Consequently, it is suggested that the corrosion resistance of the weld metal zone surely depends on the chemical components of each filler metal and welding method irrespective of the types of piston crown material.

A comparative evaluation of polymerization stress data obtained with four different mechanical testing systems.

PubMed

Gonçalves, Flávia; Boaro, Leticia C; Ferracane, Jack L; Braga, Roberto R

2012-06-01

The null hypothesis was that mechanical testing systems used to determine polymerization stress (σ(pol)) would rank a series of composites similarly. Two series of composites were tested in the following systems: universal testing machine (UTM) using glass rods as bonding substrate, UTM/acrylic rods, "low compliance device", and single cantilever device ("Bioman"). One series had five experimental composites containing BisGMA:TEGDMA in equimolar concentrations and 60, 65, 70, 75 or 80 wt% of filler. The other series had five commercial composites: Filtek Z250 (3M ESPE), Filtek A110 (3M ESPE), Tetric Ceram (Ivoclar), Heliomolar (Ivoclar) and Point 4 (Kerr). Specimen geometry, dimensions and curing conditions were similar in all systems. σ(pol) was monitored for 10 min. Volumetric shrinkage (VS) was measured in a mercury dilatometer and elastic modulus (E) was determined by three-point bending. Shrinkage rate was used as a measure of reaction kinetics. ANOVA/Tukey test was performed for each variable, separately for each series. For the experimental composites, σ(pol) decreased with filler content in all systems, following the variation in VS. For commercial materials, σ(pol) did not vary in the UTM/acrylic system and showed very few similarities in rankings in the others tests system. Also, no clear relationships were observed between σ(pol) and VS or E. The testing systems showed a good agreement for the experimental composites, but very few similarities for the commercial composites. Therefore, comparison of polymerization stress results from different devices must be done carefully. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

A new classification system for all-ceramic and ceramic-like restorative materials.

PubMed

Gracis, Stefano; Thompson, Van P; Ferencz, Jonathan L; Silva, Nelson R F A; Bonfante, Estevam A

2015-01-01

Classification systems for all-ceramic materials are useful for communication and educational purposes and warrant continuous revisions and updates to incorporate new materials. This article proposes a classification system for ceramic and ceramic-like restorative materials in an attempt to systematize and include a new class of materials. This new classification system categorizes ceramic restorative materials into three families: (1) glass-matrix ceramics, (2) polycrystalline ceramics, and (3) resin-matrix ceramics. Subfamilies are described in each group along with their composition, allowing for newly developed materials to be placed into the already existing main families. The criteria used to differentiate ceramic materials are based on the phase or phases present in their chemical composition. Thus, an all-ceramic material is classified according to whether a glass-matrix phase is present (glass-matrix ceramics) or absent (polycrystalline ceramics) or whether the material contains an organic matrix highly filled with ceramic particles (resin-matrix ceramics). Also presented are the manufacturers' clinical indications for the different materials and an overview of the different fabrication methods and whether they are used as framework materials or monolithic solutions. Current developments in ceramic materials not yet available to the dental market are discussed.

Iatrogenic occlusion of the ophthalmic artery after cosmetic facial filler injections: a national survey by the Korean Retina Society.

PubMed

Park, Kyu Hyung; Kim, Yong-Kyu; Woo, Se Joon; Kang, Se Woong; Lee, Won Ki; Choi, Kyung Seek; Kwak, Hyung Woo; Yoon, Ill Han; Huh, Kuhl; Kim, Jong Woo

2014-06-01

Iatrogenic occlusion of the ophthalmic artery and its branches is a rare but devastating complication of cosmetic facial filler injections. To investigate clinical and angiographic features of iatrogenic occlusion of the ophthalmic artery and its branches caused by cosmetic facial filler injections. Data from 44 patients with occlusion of the ophthalmic artery and its branches after cosmetic facial filler injections were obtained retrospectively from a national survey completed by members of the Korean Retina Society from 27 retinal centers. Clinical features were compared between patients grouped by angiographic findings and injected filler material. Visual prognosis and its relationship to angiographic findings and injected filler material. Ophthalmic artery occlusion was classified into 6 types according to angiographic findings. Twenty-eight patients had diffuse retinal and choroidal artery occlusions (ophthalmic artery occlusion, generalized posterior ciliary artery occlusion, and central retinal artery occlusion). Sixteen patients had localized occlusions (localized posterior ciliary artery occlusion, branch retinal artery occlusion, and posterior ischemic optic neuropathy). Patients with diffuse occlusions showed worse initial and final visual acuity and less visual gain compared with those having localized occlusions. Patients receiving autologous fat injections (n = 22) had diffuse ophthalmic artery occlusions, worse visual prognosis, and a higher incidence of combined brain infarction compared with patients having hyaluronic acid injections (n = 13). Clinical features of iatrogenic occlusion of the ophthalmic artery and its branches following cosmetic facial filler injections were diverse according to the location and extent of obstruction and the injected filler material. Autologous fat injections were associated with a worse visual prognosis and a higher incidence of combined cerebral infarction. Extreme caution and care should be taken during these injections, and physicians should be aware of a diverse spectrum of complications following cosmetic facial filler injections.

Method for manufacturing lightning strike mitigation composites

NASA Technical Reports Server (NTRS)

Vaidyanathan, K. Ranji (Inventor); Campbell, Jeffrey (Inventor)

2012-01-01

A method for manufacturing a composite material utilizes a tooling material having a desired shape. The surface of the tooling material is coated with a composite film that includes a conductive filler material. A composite composition is introduced into contact with the surface of the tooling material to form a desired shape. The composite composition is processed to produce the composite material, and the composite material has a conductive composite surface layer that includes the conductive filler material.

Tetraethyl orthosilicate-based glass composition and method

DOEpatents

Wicks, George G.; Livingston, Ronald R.; Baylor, Lewis C.; Whitaker, Michael J.; O'Rourke, Patrick E.

1997-01-01

A tetraethyl orthosilicate-based, sol-gel glass composition with additives selected for various applications. The composition is made by mixing ethanol, water, and tetraethyl orthosilicate, adjusting the pH into the acid range, and aging the mixture at room temperature. The additives, such as an optical indicator, filler, or catalyst, are then added to the mixture to form the composition which can be applied to a substrate before curing. If the additive is an indicator, the light-absorbing characteristics of which vary upon contact with a particular analyte, the indicator can be applied to a lens, optical fiber, reagant strip, or flow cell for use in chemical analysis. Alternatively, an additive such as alumina particles is blended into the mixture to form a filler composition for patching cracks in metal, glass, or ceramic piping.

Hybrid waste filler filled bio-polymer foam composites for sound absorbent materials

NASA Astrophysics Data System (ADS)

Rus, Anika Zafiah M.; Azahari, M. Shafiq M.; Kormin, Shaharuddin; Soon, Leong Bong; Zaliran, M. Taufiq; Ahraz Sadrina M. F., L.

2017-09-01

Sound absorption materials are one of the major requirements in many industries with regards to the sound insulation developed should be efficient to reduce sound. This is also important to contribute in economically ways of producing sound absorbing materials which is cheaper and user friendly. Thus, in this research, the sound absorbent properties of bio-polymer foam filled with hybrid fillers of wood dust and waste tire rubber has been investigated. Waste cooking oil from crisp industries was converted into bio-monomer, filled with different proportion ratio of fillers and fabricated into bio-polymer foam composite. Two fabrication methods is applied which is the Close Mold Method (CMM) and Open Mold Method (OMM). A total of four bio-polymer foam composite samples were produce for each method used. The percentage of hybrid fillers; mixture of wood dust and waste tire rubber of 2.5 %, 5.0%, 7.5% and 10% weight to weight ration with bio-monomer. The sound absorption of the bio-polymer foam composites samples were tested by using the impedance tube test according to the ASTM E-1050 and Scanning Electron Microscope to determine the morphology and porosity of the samples. The sound absorption coefficient (α) at different frequency range revealed that the polymer foam of 10.0 % hybrid fillers shows highest α of 0.963. The highest hybrid filler loading contributing to smallest pore sizes but highest interconnected pores. This also revealed that when highly porous material is exposed to incident sound waves, the air molecules at the surface of the material and within the pores of the material are forced to vibrate and loses some of their original energy. This is concluded that the suitability of bio-polymer foam filled with hybrid fillers to be used in acoustic application of automotive components such as dashboards, door panels, cushion and etc.

Microstructural evolution of SiC joints soldered using Zn-Al filler metals with the assistance of ultrasound.

PubMed

Wu, Bingzhi; Leng, Xuesong; Xiu, Ziyang; Yan, Jiuchun

2018-06-01

SiC ceramics were successfully soldered with the assistance of ultrasound. Two kinds of filler metals, namely non-eutectic Zn-5Al-3Cu and eutectic Zn-5Al alloys, were used. The effects of ultrasonic action on the microstructure and mechanical properties of the soldered joints were investigated. The results showed that ultrasound could promote the wetting and bonding between the SiC ceramic and filler metals within tens of seconds. For the Zn-5Al-3Cu solder, a fully grain-refined structure in the bond layer was obtained as the ultrasonic action time increased. This may lead to a substantial enhancement in the strength of the soldered joints. For the Zn-5Al solder, the shear strength of the soldered joints was only ∼102 MPa when the ultrasonic action time was shorter, and fractures occurred in the brittle lamellar eutectic phases in the center of the bond layer. With increasing ultrasonic action time, the lamellar eutectic phase in the bond layer of SiC joints could be completely transformed to a fine non-lamellar eutectic structure. Meanwhile, the grains in the bond layer were obviously refined. Those results led to the remarkable enhancement of the shear strength of the joints (∼138 MPa) using the Zn-5Al solder, which had approached that enhancement using the Zn-5Al-3Cu solder. The enhanced mechanical properties of the joints were attributed to the significant refinement of the grains and the change in the eutectic structure in the bond layer. Prolonged enhanced heterogeneous nucleation triggered by ultrasonic cavitation is the predominant refinement mechanism of the bond metals of the SiC joints. Copyright © 2018 Elsevier B.V. All rights reserved.

System compliance dictates the effect of composite filler content on polymerization shrinkage stress.

PubMed

Wang, Zhengzhi; Chiang, Martin Y M

2016-04-01

The effect of filler content in dental restorative composites on the polymerization shrinkage stress (PS) is not straightforward and has caused much debate in the literature. Our objective in this study was to clarify the PS/filler content relationship based on analytical and experimental approaches, so that guidelines for materials comparison in terms of PS and clinical selection of dental composites with various filler content can be provided. Analytically, a simplified model based on linear elasticity was utilized to predict PS as a function of filler content under various compliances of the testing system, a cantilever beam-based instrument used in this study. The predictions were validated by measuring PS of composites synthesized using 50/50 mixtures of two common dimethacrylate resins with a variety of filler contents. Both experiments and predictions indicated that the influence of filler content on the PS highly depended on the compliance of the testing system. Within the clinic-relevant range of compliances and for the specific sample configuration tested, the PS increased with increasing filler content at low compliance of instrument, while increasing the compliance caused the effect of filler content on the PS to gradually diminish. Eventually, at high compliance, the PS inverted and decreased with increasing filler content. This compliance-dependent effect of filler content on PS suggests: (1) for materials comparison in terms of PS, the specific compliance at which the comparison being done should always be reported and (2) clinically, composites with relatively lower filler content could be selected for such cavities with relatively lower compliance (e.g. a Class-I cavity with thick tooth walls or the basal part in a cavity) and vice versa in order to reduce the final PS. Published by Elsevier Ltd.

Evaluation of Different Mineral Filler Aggregates for Asphalt Mixtures

NASA Astrophysics Data System (ADS)

Wasilewska, Marta; Małaszkiewicz, Dorota; Ignatiuk, Natalia

2017-10-01

Mineral filler aggregates play an important role in asphalt mixtures because they fill voids in paving mix and improve the cohesion of asphalt binder. Limestone powder containing over 90% of CaCO3 is the most frequently used type of filler. Waste material from the production of coarse aggregate can be successfully used as a mineral filler aggregate for hot asphalt concrete mixtures as the limestone powder replacement. This paper presents the experimental results of selected properties of filler aggregates which were obtained from rocks with different mineral composition and origin. Five types of rocks were used as a source of the mineral filler aggregate: granite, gabbro, trachybasalt, quartz sandstone and rocks from postglacial deposits. Limestone filler was used in this study as the reference material. The following tests were performed: grading (air jet sieving), quality of fines according to methylene blue test, water content by drying in a ventilated oven, particle density using pyknometer method, Delta ring and ball test, Bitumen Number, fineness determined as Blaine specific surface area. Mineral filler aggregates showed significant differences when they were mixed with bitumen and stiffening effect in Delta ring and ball test was evaluated. The highest values were achieved when gabbro and granite fillers were used. Additionally, Scanning Electron Microscopy (SEM) analysis of grain shape and size was carried out. Significant differences in grain size and shape were observed. The highest non-homogeneity in size was determined for quartz sandstone, gabbro and granite filler. Their Blaine specific surface area was lower than 2800 cm2/g, while for limestone and postglacial fillers with regular and round grains it exceeded 3000 cm2/g. All examined mineral filler aggregates met requirements of Polish National Specification WT-1: 2014 and could be used in asphalt mixtures.

Effect on mechanical properties of glass reinforced epoxy (GRE) pipe filled with different geopolymer filler molarity for piping application

NASA Astrophysics Data System (ADS)

Hashim, M. F. Abu; Abdullah, M. M. A.; Ghazali, C. M. R.; Hussin, K.; Binhussain, M.

2017-04-01

This study investigated the use of a novel white clay geopolymer as a filler to produce high strength glass reinforced epoxy pipe. It was found that using white clay geopolymer as filler gives better compressive strength to the glass reinforced epoxy pipe. The disadvantages of current glass reinforced epoxy pipes such low compressive strength which can be replaced by the composite pipes. Geopolymerization is an innovative technology that can transform several aluminosilicate materials into useful products called geopolymers or inorganic polymers. A series of glass reinforced epoxy pipe and glass reinforced epoxy pipe filled with 10 - 40 weight percentages white clay geopolymer filler with 4 Molarity and 8 Molarity were prepared. Morphology of white clay geopolymer filler surface was indicates using scanning electron microscopy. The additions of white clay geopolymer filler for both 4 Molarity and 8 Molarity show higher compressive strength than glass reinforced epoxy pipe without any geopolymer filler. The compressive test of these epoxy geopolymer pipe samples was determined using Instron Universal Testing under compression mode. Nonetheless, the compressive strength of glass reinforced epoxy pipe with white clay geopolymer filler continues to drop when added to 40 wt% of the geopolymer filler loading for both 4 Molarity and 8 Molarity. These outcomes showed that the mixing of geopolymer materials in epoxy system can be attained in this research.

Effects of Temperature and Steam Environment on Fatigue Behavior of Three SIC/SIC Ceramic Matrix Composites

DTIC Science & Technology

2008-09-01

Infiltration (CVI), Chemical Vapor Deposition (CVD) and polymer impregnation/ pyrolysis (PIP) [5:20, 32]. The SiC fibers currently... composite was infiltrated with a mixture of polymer , filler particles and solvent. During pyrolysis under nitrogen at temperatures > 1000 °C, the...using polymer infiltration and pyrolysis (PIP) method. Polymer infiltration and pyrolysis processing method allows near-net-shape molding and

Biodegradation of natural reinforcing fillers for polymer composites

NASA Astrophysics Data System (ADS)

Mastalygina, E. E.; Pantyukhov, P. V.; Popov, A. A.

2018-05-01

Twelve different natural raw materials were selected as possible fillers for eco-friendly biocomposites. The target was to find the most biodegradable ones. Two mycological tests were held: in the aqueous and agar media. It was found that two tests showed different results. In aqueous media, the fillers with a high content of water-soluble and easy-hydrolysed compounds demostrated the most intensive biofouling. In agar media, the entire filler was exposed to biodigestion by fungi. Therefore, multi-compound fillers with a set of different macro- and microelements were more biodegradable than others.

Composite materials comprising two jonal functions and methods for making the same

DOEpatents

Fareed, Ali Syed; Garnier, John Edward; Schiroky, Gerhard Hans; Kennedy, Christopher Robin; Sonuparlak, Birol

2001-01-01

The present invention generally relates to mechanisms for preventing undesirable oxidation (i.e., oxidation protection mechanisms) in composite bodies. The oxidation protection mechanisms include getterer materials which are added to the composite body which gather or scavenge undesirable oxidants which may enter the composite body. The getterer materials may be placed into at least a portion of the composite body such that any undesirable oxidant approaching, for example, a fiber reinforcement, would be scavenged by (e.g., reacted with) the getterer. The getterer materials) may form at least one compound which acts as a passivation layer, and/or is able to move by bulk transport (e.g., by viscous flow as a glassy material) to a crack, and sealing the crack, thereby further enhancing the oxidation protection of the composite body. One or more ceramic filler materials which serve as reinforcements may have a plurality of super-imposed coatings thereon, at least one of which coatings may function as or contain an oxidation protection mechanism. Specifically, a coating comprising boron nitride which has been engineered or modified to contain some silicon exhibits improved corrosion resistance, specifically to oxygen and moisture. The coated materials may be useful as reinforcing materials in high performance composites to provide improved mechanical properties such as fracture toughness. The present invention also relates to improved composites which incorporate these materials, and to their methods of manufacture.

Characterization Tests for Mineral Fillers Related to Performance of Asphalt Paving Mixtures

DOT National Transportation Integrated Search

1988-01-01

Various studies have shown that the properties of mineral filler, especially the material passing 0.075 mm (No. 200) sieve (generally called P200 material), have a significant effect on the performance of asphalt paving mixtures in terms of permanent...

Influence of fillers on the alkali activated chamotte

NASA Astrophysics Data System (ADS)

Dembovska, L.; Bumanis, G.; Vitola, L.; Bajare, D.

2017-10-01

Alkali-activated materials (AAM) exhibit remarkable high-temperature resistance which makes them perspective materials for high-temperature applications, for instance as fire protecting and insulating materials in industrial furnaces. Series of experiments were carried out to develop optimum mix proportions of AAM based on chamotte with quartz sand (Q), olivine sand (OL) and firebrick sawing residues (K26) as fillers. Aluminium scrap recycling waste was considered as a pore forming agent and 6M NaOH alkali activation solution has been used. Lightweight porous AAM have been obtained with density in range from 600 to 880 kg/m3 and compressive strength from 0.8 to 2.7 MPa. The XRD and high temperature optical microscopy was used to characterize the performance of AAM. The mechanical, physical and structural properties of the AAM were determined after the exposure to elevated temperatures at 800 and 1000°C. The results indicate that most promising results for AAM were with K26 filler where strength increase was observed while Q and OL filler reduced mechanical properties due to structure deterioration caused by expansive nature of selected filler.

Microstructure and dielectric properties of silver-barium titanate nanocomplex materials by wet chemical approach

NASA Astrophysics Data System (ADS)

Ueno, Shintaro; Sakamoto, Yasunao; Nakashima, Kouichi; Wada, Satoshi

2014-09-01

To develop ceramic capacitors with a high effective dielectric constant, we attempted to fabricate BaTiO3 (BT) complexes with embedded Ag nanoparticles by wet chemical processes. Ag nanoparticle-adsorbed dendritic BT particles, Ag-BT hybrid particles, were synthesized from the sol-gel-derived precursor gel powders containing Ag, Ba, and Ti by hydrothermal treatment. These particles were pressed with BT fillers and TiO2 precursor nanoparticles into green compacts, and then, the green compacts were chemically converted into the Ag/BT nanocomplex compacts in Ba(OH)2 aqueous solution under the hydrothermal condition at 160 °C. The effective dielectric constant of the resultant Ag/BT nanocomplexes increases with an increase in Ag content. The maximal effective dielectric constant of approximately 900 was recorded for the nanocomplex with the Ag content of 10.7 vol %.

73rd American Welding Society annual meeting

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

Not Available

1992-01-01

The volume includes the abstracts of papers presented at the 73rd American Welding Society Annual Meeting. Detailed summaries are given for 118 technical sessions papers discussing computer and control applications in welding, stainless steel, nickel and nickel alloys, weld metal microstructure, shipbuilding, consumables, structural welding, investigations in arc welding and cutting, arc welding processes, weldability testing, piping and tubing, high energy beam welding processes, welding metallurgy of structural steels, new applications, weld metal behavior, NDT certification, aluminum welding, submerged arc welding, modeling studies, resistance welding, friction welding, and safety and health. The 23rd International AWS Brazing and Soldering Conference wasmore » also held during this meeting. The topics presented in 24 papers included recent developments in soldering technology, brazing of stainless steel, brazing of ceramics and nickel material, filler metal developments for torch brazing, and developments in diffusion and induction brazing.« less

Three-body-wear resistance of the experimental composites containing filler treated with hydrophobic silane coupling agents.

PubMed

Nihei, Tomotaro; Dabanoglu, Alp; Teranaka, Toshio; Kurata, Shigeaki; Ohashi, Katsura; Kondo, Yukishige; Yoshino, Norio; Hickel, Reinhard; Kunzelmann, Karl-Heinz

2008-06-01

This paper evaluated the wear resistance of resin composite materials with fillers which were modified with a novel hydrophobic silane coupling agent. The novel silane coupling agent containing hydrophobic phenyl group 3-(3-methoxy-4-methacryloyloxyphenyl)propyltrimethoxysilane (p-MBS) was synthesized. The experimental light-cure hybrid composites containing 85wt% of filler modified with this silane were formulated. Twelve specimens were prepared for the three-body-wear test with the ACTA machine and the collected data were analyzed statistically using a one-way ANOVA and Tukey's multiple comparison test as the post hoc test. The wear of the composites containing fillers treated with p-MBS was significantly lower compared with the composite materials containing fillers pretreated with 3-methacryloyloxypropyltrimethoxysilane or the commercially composites (AP-X and ELS extra low shrinkage) after a wear test for 200,000 cycles (p<0.05). It is suggested that the resin composites containing fillers modified with the novel hydrophobic silane has high wear resistant, because of the coupling layers treated with this silane had an excellent affinity with the base resin and formed a highly hydrophobic layer on the filler surface.

Morphology and viscoelastic properties of sealing materials based on EPDM rubber.

PubMed

Milić, J; Aroguz, A; Budinski-Simendić, J; Radicević, R; Prendzov, S

2008-12-01

In this applicative study, the ratio of active and inactive filler loadings was the prime factor for determining the dynamic-mechanical behaviour of ethylene-propylene-diene monomer rubbers. Scanning electron microscopy was used to study the structure of reinforced dense and microcellular elastomeric materials. The effects of filler and blowing agent content on the morphology of composites were investigated. Microcellular samples cured in salt bath show smaller cells and uniform cell size compared with samples cured in hot air. Dynamic-mechanical thermal analysis showed appreciable changes in the viscoelastic properties by increasing active filler content, which could enable tailoring the material properties to suit sealing applications.

Properties of concrete containing coconut shell powder (CSP) as a filler

NASA Astrophysics Data System (ADS)

Leman, A. S.; Shahidan, S.; Nasir, A. J.; Senin, M. S.; Zuki, S. S. Mohd; Ibrahim, M. H. Wan; Deraman, R.; Khalid, F. S.; Azhar, A. T. S.

2017-11-01

Coconut shellsare a type of agricultural waste which can be converted into useful material. Therefore,this study was conducted to investigate the properties of concrete which uses coconut shell powder (CSP) filler material and to define the optimum percentage of CSP which can be used asfiller material in concrete. Comparisons have been made between normal concrete mixes andconcrete containing CSP. In this study, CSP was added into concrete mixes invaryingpercentages (0%, 2%, 4%, 6%, 8% and 10%). The coconut shell was grounded into afine powder before use. Experimental tests which have been conducted in this study include theslump test, compressive test and splitting tensile strength test. CSP have the potential to be used as a concrete filler and thus the findings of this study may be applied to the construction industry. The use of CSP as a filler in concrete can help make the earth a more sustainable and greener place to live in.

X-ray tomography of powder injection moulded micro parts using synchrotron radiation

NASA Astrophysics Data System (ADS)

Heldele, R.; Rath, S.; Merz, L.; Butzbach, R.; Hagelstein, M.; Haußelt, J.

2006-05-01

Powder injection moulding is one of the most promising replication methods for the mass production of metal and ceramic micro parts. The material for injection moulding, a so-called feedstock, consists of thermoplastic binder components and inorganic filler with approximately equal volume fractions. Injection moulding of the feedstock leads to a green part that can be processed to a dense metal or ceramic micro part by debinding and sintering. During the injection moulding process extremely high shear rates are applied. This promotes the separation of powder and binder leading to a particle density variation in the green part causing anisotropic shrinkage during post-processing. The knowledge of introducing density gradients and defects would consequently allow the optimization of the feedstock, the moulding parameters and the validation of a simulation tool based on the Dissipative Particle Dynamics which is currently under development, as well. To determine the particle density and defect distribution in micro parts synchrotron radiation tomography in absorption mode was used. Due to its parallel and monochromatic character a quantitative reconstruction, free of beam hardening artifacts, is possible. For the measurement, bending bars consisting of dispersed fused silica particles in a polymeric matrix were used. The presented results using this set-up show that crucial defects and density variations can be detected.

The volumetric fraction of inorganic particles and the flexural strength of composites for posterior teeth.

PubMed

Adabo, Gelson Luis; dos Santos Cruz, Carlos Alberto; Fonseca, Renata Garcia; Vaz, Luís Geraldo

2003-07-01

To evaluate the content of inorganic particles and the flexural strength of new condensable composites for posterior teeth in comparison to hybrid conventional composites. The determination of the content of inorganic particles was performed by mass weighing of a polymerized composite before and after the elimination of the organic phase. The volumetric particle content was determined by a practical method based on Archimedes' principle, which calculates the volume of the composite and their particles by differential mass measured in the air and in water. The flexural strength of three points was evaluated according to the norm ISO 4049:1988. The results showed the following filler content: Alert, 67.26%; Z-100, 65.27%; Filtek P 60, 62.34%; Ariston pHc, 64.07%; Tetric Ceram, 57.22%; Definite, 54.42%; Solitaire, 47.76%. In the flexural strength test, the materials presented the following decreasing order of resistance: Filtek P 60 (170.02 MPa)>Z-100 (151.34 MPa)>Tetric Ceram (126.14 MPa)=Alert (124.89 MPa)>Ariston pHc (102.00 MPa)=Definite (93.63 MPa)>Solitaire (56.71 MPa). New condensable composites for posterior teeth present a concentration of inorganic particles similar to those of hybrid composites but do not necessarily present higher flexural strength.

Quantitative Electron Tomography of Rubber Composites

NASA Astrophysics Data System (ADS)

Staniewicz, Lech; Vaudey, Thomas; Degrandcourt, Christophe; Couty, Marc; Gaboriaud, Fabien; Midgley, Paul

2014-06-01

Rubber composite materials have many applications, one example being tyre manufacture. The presence of a filler material in the composite (such as carbon black or silica) causes its mechanical properties to differ in several ways when compared to pure rubber such as viscoelastic behaviour (the Payne effect), increased tensile strength and improved wear resistance. To fully understand these properties, it is necessary to characterise how the filler material is organised on the nanoscale. Using composite materials representative of those found in tyres, this work illustrates the use of electron tomography and machine learning methods as tools to describe the percolation behaviour of the filler; in this case, we focus on the largest proportion of particles absorbed into one single object as a function of particle spacing.

Physico-mechanical characteristics of commercially available bulk-fill composites.

PubMed

Leprince, Julian G; Palin, William M; Vanacker, Julie; Sabbagh, Joseph; Devaux, Jacques; Leloup, Gaetane

2014-08-01

Bulk-fill composites have emerged, arguably, as a new "class" of resin-based composites, which are claimed to enable restoration in thick layers, up to 4mm. The objective of this work was to compare, under optimal curing conditions, the physico-mechanical properties of most currently available bulk-fill composites to those of two conventional composite materials chosen as references, one highly filled and one flowable "nano-hybrid" composite. Tetric EvoCeram Bulk Fill (Ivoclar-Vivadent), Venus Bulk Fill (Heraeus-Kulzer), SDR (Dentsply), X-tra Fil (VOCO), X-tra Base (VOCO), Sonic Fill (Kerr), Filtek Bulk Fill (3M-Espe), Xenius (GC) were compared to the two reference materials. The materials were light-cured for 40s in a 2mm×2mm×25mm Teflon mould. Degree of conversion was measured by Raman spectroscopy, Elastic modulus and flexural strength were evaluated by three point bending, surface hardness using Vickers microindentation before and after 24h ethanol storage, and filler weight content by thermogravimetric analysis. The ratio of surface hardness before and after ethanol storage was considered as an evaluation of polymer softening. Data were analyzed by one-way ANOVA and post hoc Tukey's test (p=0.05). The mechanical properties of the bulk-fill composites were mostly lower compared with the conventional high viscosity material, and, at best, comparable to the conventional flowable composite. Linear correlations of the mechanical properties investigated were poor with degree of conversion (0.090.8). Softening in ethanol revealed differences in polymer network density between material types. The reduction of time and improvement of convenience associated with bulk-fill materials is a clear advantage of this particular material class. However, a compromise with mechanical properties compared with more conventional commercially-available nano-hybrid materials was demonstrated by the present work. Given the lower mechanical properties of most bulk-fill materials compared to a highly filled nano-hybrid composite, their use for restorations under high occlusal load is subject to caution. Further, the swelling behaviour of some of the bulk-fill materials may be a reason for concern, which highlights the critical requirement for a veneering material, not only to improve aesthetic quality of the translucent material, but to reduce the impact of degradation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Influence of filler charge on gloss of composite materials before and after in vitro toothbrushing.

PubMed

Jassé, Fernanda Ferreira; de Campos, Edson Alves; Lefever, Dorien; Di Bella, Enrico; Salomon, Jean Pierre; Krejci, Ivo; Ardu, Stefano

2013-11-01

This study evaluated the gloss behaviour of experimental resin composites loaded with different filler percentages, immediately after polishing and after toothbrushing simulation. Sixteen disc-shaped specimens were fabricated for each different-charged composite (40%, 50%, 60%, 70% and 75%) and polished with SiC abrasive papers. Gloss measurements were made prior to simulated toothbrushing. The specimens were subjected to the simulation for 5, 15, 30 and 60 min using an electrical toothbrush with a standardized pressure while being immersed in a toothpaste/artificial saliva slurry. Baseline composite gloss values ranged from 69.7 (40%) to 81.3 (75%) GU (gloss units) and from 18.1 (40%) to 32.3 (75%) GU after 1h of brushing. Highest gloss values were obtained by 75%-charged resin, while the lowest values were obtained by the 40%-charged one. All tested materials showed a gloss decrease. However, the higher filler load a composite resin has, the higher gloss it can achieve. Gloss of resin composite materials is an important factor in determining aesthetic success of anterior restorations, and this property may vary according to the filler charge of the restorative material. Higher filler load of a composite resin results in higher gloss values. Copyright © 2013 Elsevier Ltd. All rights reserved.

Waste-wood-derived fillers for plastics

Treesearch

Brent English; Craig M. Clemons; Nicole Stark; James P. Schneider

1996-01-01

Filled thermoplastic composites are stiffer, stronger, and more dimensionally stable than their unfilled counterparts. Such thermoplastics are usually provided to the end-user as a precompounded, pelletized feedstock. Typical reinforcing fillers are inorganic materials like talc or fiberglass, but materials derived from waste wood, such as wood flour and recycled paper...

Composite Materials for Maxillofacial Prostheses.

DTIC Science & Technology

1981-08-01

necessary and Identify byv block number) MAXILLOFACIAL PROSTHESES; PROSTHETIC MATERIALS: MICROCAPSULES : SOFT FILLERS; ELASTOMER COMPOSITES 2,. ABSTRACT...used as fillers in the fabrication of maxillofacial prostheses. The projected systems are elastomeric-shelled, liquid-filled microcapsules . Improvements...elastomeric-shelled, liquid-filled microcapsules . Experiments continued on the interfacial polymerization process, with spherical, sealed, capsules

Tetraethyl orthosilicate-based glass composition and method

DOEpatents

Wicks, G.G.; Livingston, R.R.; Baylor, L.C.; Whitaker, M.J.; O`Rourke, P.E.

1997-06-10

A tetraethyl orthosilicate-based, sol-gel glass composition with additives selected for various applications is described. The composition is made by mixing ethanol, water, and tetraethyl orthosilicate, adjusting the pH into the acid range, and aging the mixture at room temperature. The additives, such as an optical indicator, filler, or catalyst, are then added to the mixture to form the composition which can be applied to a substrate before curing. If the additive is an indicator, the light-absorbing characteristics of which vary upon contact with a particular analyte, the indicator can be applied to a lens, optical fiber, reagent strip, or flow cell for use in chemical analysis. Alternatively, an additive such as alumina particles is blended into the mixture to form a filler composition for patching cracks in metal, glass, or ceramic piping. 12 figs.

Influence of the porosity on the dispersion of the phase velocity of longitudinal acoustic waves in isotropic metal-matrix composites

NASA Astrophysics Data System (ADS)

Karabutov, A. A.; Podymova, N. B.

2017-05-01

The influence of the volumetric porosity of isotropic metal-matrix composite materials, which are reinforced with ceramic microparticles, on the dispersion of the phase velocity of longitudinal acoustic waves is investigated. For this purpose, the method of broadband acoustic spectroscopy with a laser source of ultrasound and piezoelectric detection of nanosecond ultrasonic pulses is used. Composite samples based on a silumin matrix with added silicon carbide (SiC) microparticles in different mass concentrations (3.8-15.5%) were investigated. As the concentration of SiC particles in a sample increases, its porosity that is determined using the hydrostatic-weighing method also increases. The simultaneous increase in the filler concentration and porosity leads to the appearance of a dispersion of the phase velocity of longitudinal acoustic waves in the sample within the frequency range of 3-25 MHz. The obtained empirical relationship between the relative change in the phase velocity and the sample porosity can be used to obtain a proximate quantitative estimate of the bulk porosity of the isotropic metal-matrix composite materials.

Augmentation of tibial plateau fractures with an injectable bone substitute: CERAMENT™. Three year follow-up from a prospective study.

PubMed

Iundusi, Riccardo; Gasbarra, Elena; D'Arienzo, Michele; Piccioli, Andrea; Tarantino, Umberto

2015-05-13

Reduction of tibial plateau fractures and maintain a level of well aligned congruent joint is key to a satisfactory clinical outcome and is important for the return to pre-trauma level of activity. Stable internal fixation support early mobility and weight bearing. The augmentation with bone graft substitute is often required to support the fixation to mantain reduction. For these reasons there has been development of novel bone graft substitutes for trauma applications and in particular synthetic materials based on calcium phosphates and/or apatite combined with calcium sulfates. Injectable bone substitutes can optimize the filling of irregular bone defects. The purpose of this study was to assess the potential of a novel injectable bone substitute CERAMENT™|BONE VOID FILLER in supporting the initial reduction and preserving alignment of the joint surface until fracture healing. From June 2010 through May 2011 adult patients presenting with acute, closed and unstable tibial plateau fractures which required both grafting and internal fixation, were included in a prospective study with percutaneous or open reduction and internal fixation (ORIF) augmented with an injectable ceramic biphasic bone substitute CERAMENT™|BONE VOID FILLER (BONESUPPORT™, Lund, Sweden) to fill residual voids. Clinical follow up was performed at 1, 3, 9 and 12 months and any subsequent year; including radiographic analysis and Rasmussen system for knee functional grading. Twenty four patients, balanced male-to-female, with a mean age of 47 years, were included and followed with an average of 44 months (range 41-52 months). Both Schatzker and Müller classifications were used and was type II or 41-B3 in 7 patients, type III or 41-B2 in 12 patients, type IV or 41-C1 in 2 patients and type VI or 41-C3 in 3 patients, respectively. The joint alignement was satisfactory and manteined within a range of 2 mm, with an average of 1.18 mm. The mean Rasmussen knee function score was 26.5, with 14 patients having an excellent result and the remaining 10 with a good result. It can be concluded that radiological and clinical outcome was satisfactory and obtained in all cases without complications. This injectable novel biphasic hydroxyapatite and calcium sulfate ceramic material is a valuable armamentarium in the treatment of trauma where bone graft is required.

Fabrication and anti-microbial evaluation of drug loaded polylactide space filler intended for ridge preservation following tooth extraction

PubMed Central

Thomas, Nebu George; Sanil, George P.; Rajmohan, Gopimohan; Prabhakaran, Jayachandran V.; Panda, Amulya K.

2011-01-01

Background: The preservation or reduction of alveolar ridge resorption following tooth extraction is important in patients especially for those intended for implants at a later stage. One way to achieve this is by using membranes, graft materials, and biodegradable space fillers to prevent alveolar bone resorption and promote regeneration. A major attraction for using biodegradable and biocompatible polymers as space fillers for ridge preservation is their safety profile in comparison to xenograft materials like lyophilized bone and collagen. Materials and Methods: Biocompatible polylactide space fillers were fabricated by fusing porous polylactide particles. The sponges were loaded with drugs by placing them in the respective solutions. Pseudomonas aeruginosa was isolated from a chronic periodontitis patient and in vitro anti-microbial evaluation was done with the drug loaded sponges. Results: Chlorhexidine loaded space filler showed significant anti microbial effect against multiple drug resistant Pseudomonas aeruginosa isolated from a patient with chronic periodontitis. Conclusion: The results of this study indicate that biodegradable drug releasing polylactide space fillers has the potential to be used for ridge preservation following tooth extraction. Release of drugs in the socket may prove useful in preventing development of alveolar osteitis post extraction which can interfere with normal healing of the socket. Synthetic biodegradable polymers also exhibit a controlled degradation rate to achieve complete resorption within the intended time. PMID:22028514

Investigation on mechanical properties of welded material under different types of welding filler (shielded metal arc welding)

NASA Astrophysics Data System (ADS)

Tahir, Abdullah Mohd; Lair, Noor Ajian Mohd; Wei, Foo Jun

2018-05-01

The Shielded Metal Arc Welding (SMAW) is (or the Stick welding) defined as a welding process, which melts and joins metals with an arc between a welding filler (electrode rod) and the workpieces. The main objective was to study the mechanical properties of welded metal under different types of welding fillers and current for SMAW. This project utilized the Design of Experiment (DOE) by adopting the Full Factorial Design. The independent variables were the types of welding filler and welding current, whereas the other welding parameters were fixed at the optimum value. The levels for types of welding filler were by the models of welding filler (E6013, E7016 and E7018) used and the levels for welding current were 80A and 90A. The responses were the mechanical properties of welded material, which include tensile strength and hardness. The experiment was analyzed using the two way ANOVA. The results prove that there are significant effects of welding filler types and current levels on the tensile strength and hardness of the welded metal. At the same time, the ANOVA results and interaction plot indicate that there are significant interactions between the welding filler types and the welding current on both the hardness and tensile strength of the welded metals, which has never been reported before. This project found that when the amount of heat input with increase, the mechanical properties such as tensile strength and hardness decrease. The optimum tensile strength for welded metal is produced by the welding filler E7016 and the optimum of hardness of welded metal is produced by the welding filler E7018 at welding current of 80A.

Mechanical and optical characterization of bio-nanocomposite from pineapple leaf fiber material for food packaging

NASA Astrophysics Data System (ADS)

Nikmatin, Siti; Rudwiyanti, Jerry R.; Prasetyo, Kurnia W.; Yedi, Dwi A.

2015-01-01

The utilization of Bio-nanocomposite material that was derived from pineapple leaf fiber as filler and tapioca starch with plasticizer glycerol as a matrix for food packaging can reduce the use of plastic that usually was made from petroleum materials. It is important to develop and producethis environmental friendly plastic because of limited availability of petroleum nowadays. The process of synthesize and characterization tapioca starch with the plasticizer glycerol bionanocomposites using print method had been conducted. There were 3 samples with different filler concentration variation; 3%, 4% and 5%.The results of mechanical test from each sample showed that bio-nanocomposite with 5% filler concentration was the optimum sample with 4.6320 MPa for tensile strength test and 24.87% for the elongation test. Based on the result of optical test for each sample was gained that along with the increasing of concentration filler would make the absorbance value of the sample became decreased, bio-nanocomposite with 5% filler concentration had several peaks with low absorbance values. The first peak was in 253 nm of wavelength regionwith absorbance of 0.131%, and the second peak was in 343 nmwavelength region and absorbance was 0.087%.

Properties of Experimental Dental Composites Containing Antibacterial Silver-Releasing Filler.

PubMed

Stencel, Robert; Kasperski, Jacek; Pakieła, Wojciech; Mertas, Anna; Bobela, Elżbieta; Barszczewska-Rybarek, Izabela; Chladek, Grzegorz

2018-06-18

Secondary caries is one of the important issues related to using dental composite restorations. Effective prevention of cariogenic bacteria survival may reduce this problem. The aim of this study was to evaluate the antibacterial activity and physical properties of composite materials with silver sodium hydrogen zirconium phosphate (SSHZP). The antibacterial filler was introduced at concentrations of 1%, 4%, 7%, 10%, 13%, and 16% ( w / w ) into model composite material consisting of methacrylate monomers and silanized glass and silica fillers. The in vitro reduction in the number of viable cariogenic bacteria Streptococcus mutans ATCC 33535 colonies, Vickers microhardness, compressive strength, diametral tensile strength, flexural strength, flexural modulus, sorption, solubility, degree of conversion, and color stability were investigated. An increase in antimicrobial filler concentration resulted in a statistically significant reduction in bacteria. There were no statistically significant differences caused by the introduction of the filler in compressive strength, diametral tensile strength, flexural modulus, and solubility. Statistically significant changes in degree of conversion, flexural strength, hardness (decrease), solubility (increase), and in color were registered. A favorable combination of antibacterial properties and other properties was achieved at SSHZP concentrations from 4% to 13%. These composites exhibited properties similar to the control material and enhanced in vitro antimicrobial efficiency.

Neutron Spectrometry for Identification of filler material in UXO - Final Report

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

Bliss, Mary

2007-09-12

Unexploded ordnance (UXO)-contaminated sites often include ordnance filled with inert substances that were used in dummy rounds. During UXO surveys, it is difficult to determine whether ordnance is filled with explosives or inert material (e.g., concrete, plaster-of-paris, wax, etc.) or is empty. Without verification of the filler material, handling procedures often necessitate that the object be blown in place, which has potential impacts to the environment, personnel, communities and survey costs. The Department of Defense (DoD) needs a reliable, timely, non-intrusive and cost-effective way to identify filler material before a removal action. A new technology that serves this purpose wouldmore » minimize environmental impacts, personnel safety risks and removal costs; and, thus, would be especially beneficial to remediation activities.« less

How to recycle asbestos containing materials (ACM)

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

Jantzen, C.M.

The current disposal of asbestos containing materials (ACM) in the private sector consists of sealing asbestos wetted with water in plastic for safe transportation and burial in regulated land fills. This disposal methodology requires large disposal volumes especially for asbestos covered pipe and asbestos/fiberglass adhering to metal framework, e.g. filters. This wrap and bury technology precludes recycle of the asbestos, the pipe and/or the metal frameworks. Safe disposal of ACM at U.S. Department of Energy (DOE) sites, likewise, requires large disposal volumes in landfills for non-radioactive ACM and large disposal volumes in radioactive burial grounds for radioactive and suspect contaminatedmore » ACM. The availability of regulated disposal sites is rapidly diminishing causing recycle to be a more attractive option. Asbestos adhering to metal (e.g., pipes) can be recycled by safely removing the asbestos from the metal in a patented hot caustic bath which prevents airborne contamination /inhalation of asbestos fibers. The dissolution residue (caustic and asbestos) can be wet slurry fed to a melter and vitrified into a glass or glass-ceramic. Palex glasses, which are commercially manufactured, are shown to be preferred over conventional borosilicate glasses. The Palex glasses are alkali magnesium silicate glasses derived by substituting MgO for B{sub 2}O{sub 3} in borosilicate type glasses. Palex glasses are very tolerant of the high MgO and high CaO content of the fillers used in forming asbestos coverings for pipes and found in boiler lashing, e.g., hydromagnesite (3MgCO{sub 3} Mg(OH){sub 2} 3H{sub 2}O) and plaster of paris, gypsum (CaSO{sub 4}). The high temperate of the vitrification process destroys the asbestos fibers and renders the asbestos non-hazardous, e.g., a glass or glass-ceramic. In this manner the glass or glass-ceramic produced can be recycled, e.g., glassphalt or glasscrete, as can the clean metal pipe or metal framework.« less

Non-Newtonian behavior observed via dynamic rheology for various particle types in energetic materials and simulant composites

NASA Astrophysics Data System (ADS)

Choi, Jong Han; Lee, Sangmook; Lee, Jae Wook

2017-02-01

The rheological properties of polymer composites highly filled with different filler materials were examined using a stress-controlled rheometer with a parallel-plate configuration, for particle characterization of the filler materials in plastic (polymer) bonded explosive (PBX). Ethylene vinyl acetate (EVA) with dioctyl adipate (DOA) was used as the matrix phase, which was shown to exhibit Newtonian-like behavior. The dispersed phase consisted of one of two energetic materials, i.e., explosive cyclotrimethylene trinitramine (RDX) or cyclotetramethylene tetranitramine (HMX), or a simulant (Dechlorane) in a bimodal size distribution. Before the test, preshearing was conducted to identify the initial condition of each sample. All examined filled polymer specimens exhibited yield stress and shear-thinning behavior over the investigated frequency range. The complex viscosity dependence on the dynamic oscillation frequency was also fitted using an appropriate rheological model, suggesting the model parameters. Furthermore, the temperature dependency of the different filler particle types was determined for different filler volume fractions. These comparative studies revealed the influence of the particle characteristics on the rheological properties of the filled polymer.

Enhancement of Fracture Toughness of Epoxy Nanocomposites by Combining Nanotubes and Nanosheets as Fillers

PubMed Central

Domun, Nadiim; Paton, Keith R.; Sainsbury, Toby; Zhang, Tao; Mohamud, Hibaaq

2017-01-01

In this work the fracture toughness of epoxy resin has been improved through the addition of low loading of single part and hybrid nanofiller materials. Functionalised multi-walled carbon nanotubes (f-MWCNTs) was used as single filler, increased the critical strain energy release rate, GIC, by 57% compared to the neat epoxy, at only 0.1 wt% filler content. Importantly, no degradation in the tensile or thermal properties of the nanocomposite was observed compared to the neat epoxy. When two-dimensional boron nitride nanosheets (BNNS) were added along with the one-dimensional f-MWCNTs, the fracture toughness increased further to 71.6% higher than that of the neat epoxy. Interestingly, when functionalised graphene nanoplatelets (f-GNPs) and boron nitride nanotubes (BNNTs) were used as hybrid filler, the fracture toughness of neat epoxy is improved by 91.9%. In neither of these hybrid filler systems the tensile properties were degraded, but the thermal properties of the nanocomposites containing boron nitride materials deteriorated slightly. PMID:29048345

Enhancement of Fracture Toughness of Epoxy Nanocomposites by Combining Nanotubes and Nanosheets as Fillers.

PubMed

Domun, Nadiim; Paton, Keith R; Hadavinia, Homayoun; Sainsbury, Toby; Zhang, Tao; Mohamud, Hibaaq

2017-10-19

In this work the fracture toughness of epoxy resin has been improved through the addition of low loading of single part and hybrid nanofiller materials. Functionalised multi-walled carbon nanotubes (f-MWCNTs) was used as single filler, increased the critical strain energy release rate, G IC , by 57% compared to the neat epoxy, at only 0.1 wt% filler content. Importantly, no degradation in the tensile or thermal properties of the nanocomposite was observed compared to the neat epoxy. When two-dimensional boron nitride nanosheets (BNNS) were added along with the one-dimensional f-MWCNTs, the fracture toughness increased further to 71.6% higher than that of the neat epoxy. Interestingly, when functionalised graphene nanoplatelets (f-GNPs) and boron nitride nanotubes (BNNTs) were used as hybrid filler, the fracture toughness of neat epoxy is improved by 91.9%. In neither of these hybrid filler systems the tensile properties were degraded, but the thermal properties of the nanocomposites containing boron nitride materials deteriorated slightly.

Generation of functional structures by laser pyrolysis of polysilazane

NASA Astrophysics Data System (ADS)

Krauss, Hans-Joachim; Otto, Andreas

2002-06-01

The pyrolysis of polysilazanes by laser power represents an innovative technique for the generation of ceramic-like coatings and structures. The dissolved polysilazanes can be easily applied by painting techniques such as dipping or spraying. In the following pyrolysis the polysilazane layer transforms into an amorphous ceramic-like coating. The laser power is absorbed in the precursor layer, which leads to the latter's ceramization without damaging the substrate by thermal load. While plane laser pyrolysis creates a protective coating, selective pyrolysis creates a raised and adherent ceramic-like structure that remains after the unexposed polymer layer has been removed. The flexibility of a writing laser system in conjunction with a suitable handling system makes it possible to inscribe any kind of 2D structure on nearly any complexly shaped part. Some of the chemical, magnetic, and electrical structure properties can be adjusted by the pyrolysis parameters and special types of filler particles. Especially the possibility to control electric conductivity should make it possible to create structure dielectric films or planar resistors, inductors or capacitors, which are basically written on the surface of the part. Because of their ceramic nature of the structures are resistant against high temperatures and corrosive media. Thus, this new additive structuring technique could finally strike a new path in creating corrosion resistant high- temperature sensors and control systems.

Surface preparation for high purity alumina ceramics enabling direct brazing in hydrogen atmospheres

DOEpatents

Cadden, Charles H.; Yang, Nancy Yuan Chi; Hosking, Floyd M.

2001-01-01

The present invention relates to a method for preparing the surface of a high purity alumina ceramic or sapphire specimen that enables direct brazing in a hydrogen atmosphere using an active braze alloy. The present invention also relates to a method for directly brazing a high purity alumina ceramic or sapphire specimen to a ceramic or metal member using this method of surface preparation, and to articles produced by this brazing method. The presence of silicon, in the form of a SiO.sub.2 -containing surface layer, can more than double the tensile bond strength in alumina ceramic joints brazed in a hydrogen atmosphere using an active Au-16Ni-0.75 Mo-1.75V filler metal. A thin silicon coating applied by PVD processing can, after air firing, produce a semi-continuous coverage of the alumina surface with a SiO.sub.2 film. Room temperature tensile strength was found to be proportional to the fraction of air fired surface covered by silicon-containing films. Similarly, the ratio of substrate fracture versus interface separation was also related to the amount of surface silicon present prior to brazing. This process can replace the need to perform a "moly-manganese" metallization step.

Characterization of morphology and composition of inorganic fillers in dental alginates.

PubMed

Guiraldo, Ricardo Danil; Berger, Sandrine Bittencourt; Consani, Rafael Leonardo Xediek; Consani, Simonides; de Carvalho, Rodrigo Varella; Lopes, Murilo Baena; Meneghel, Luciana Lira; da Silva, Fabiane Borges; Sinhoreti, Mário Alexandre Coelho

2014-01-01

Energy dispersive X-ray spectroscopy microanalysis (EDX), scanning electron microscopy (SEM), and Archimedes' Principle were used to determine the characteristics of inorganic filler particles in five dental alginates, including Cavex ColorChange (C), Hydrogum 5 (H5), Hydrogum (H), Orthoprint (O), and Jeltrate Plus (JP). The different alginate powders (0.5 mg) were fixed on plastic stubs (n = 5) and sputter coated with carbon for EDX analysis, then coated with gold, and observed using SEM. Volume fractions were determined by weighing a sample of each material in water before and after calcining at 450(°)C for 3 h. The alginate materials were mainly composed of silicon (Si) by weight (C-81.59%, H-79.89%, O-78.87%, H5-77.95%, JP-66.88%, wt). The filler fractions in volume (vt) were as follows: H5-84.85%, JP-74.76%, H-70.03%, O-68.31%, and C-56.10%. The tested materials demonstrated important differences in the inorganic elemental composition, filler fraction, and particle morphology.

Evaluation on the feasibility of using bamboo fillers in plastic gear manufacturing via the Taguchi optimization method

NASA Astrophysics Data System (ADS)

Mehat, N. M.; Kamaruddin, S.

2017-10-01

An increase in demand for industrial gears has instigated the escalating uses of plastic-matrix composites, particularly carbon or glass fibre reinforced plastics as gear material to enhance the properties and limitation in plastic gears. However, the production of large quantity of these synthetic fibres reinforced composites has posed serious threat to ecosystem. Therefore, this work is conducted to study the applicability and practical ability of using bamboo fillers particularly in plastic gear manufacturing as opposed to synthetic fibres via the Taguchi optimization method. The results showed that no failure mechanism such as gear tooth root cracking and severe tooth wear were observed in gear tested made of 5-30 wt% of bamboo fillers in comparing with the unfilled PP gear. These results indicated that bamboo can be practically and economically used as an alternative filler in plastic material reinforcement as well as in minimizing the cost of raw material in general.

Hybrid nanocomposites of 2D black phosphorus nanosheets encapsulated in PMMA polymer material: new platforms for advanced device fabrication

NASA Astrophysics Data System (ADS)

Telesio, Francesca; Passaglia, Elisa; Cicogna, Francesca; Costantino, Federica; Serrano-Ruiz, Manuel; Peruzzini, Maurizio; Heun, Stefan

2018-07-01

Hybrid materials, containing a 2D filler embedded in a polymeric matrix, are an interesting platform for several applications, because of the variety of properties that the filler can impart to the polymer matrix when dispersed at the nanoscale. Moreover, novel properties could arise from the interaction between the two. Mostly the bulk properties of these materials have been studied so far, especially focusing on how the filler changes the polymeric matrix properties. Here we propose a complete change of perspective by using the hybrid nanocomposite material as a platform suitable to engineer the properties of the filler and to exploit its potential in the fabrication of devices. As a proof of concept of the versatility and the potential of the new method, we applied this approach to prepare black phosphorus (bP) nanocomposites through its dispersion in poly (methyl methacrylate). bP is a very interesting 2D material, whose application have so far been limited by its high reactivity to oxygen and water. In this respect, we show that electronic-grade bP flakes, already embedded in a protecting matrix since their exfoliation from the bulk material, are endowed with significantly increased stability and can be further processed into devices without degrading their properties.

Hybrid Nanocomposites of 2D Black Phosphorous Nanosheets Encapsulated in PMMA Polymer Material: New Platforms for Advanced Device Fabrication.

PubMed

Telesio, Francesca; Passaglia, Elisa; Cicogna, Francesca; Costantino, Federica; Serrano-Ruiz, Manuel; Peruzzini, Maurizio; Heun, Stefan

2018-04-12

Hybrid materials, containing a 2D filler embedded in a polymeric matrix, are an interesting platform for several applications, because of the variety of properties that the filler can impart to the polymer matrix when dispersed at the nanoscale. Moreover, novel properties could arise from the interaction between the two. Mostly the bulk properties of these materials have been studied so far, especially focusing on how the filler changes the polymeric matrix properties. Here we propose a complete change of perspective by using the hybrid nanocomposite material as a platform suitable to engineer the properties of the filler and to exploit its potential in the fabrication of devices. As a proof of concept of the versatility and potentiality of the new method, we applied this approach to prepare black phosphorus nanocomposites through its dispersion in poly (methyl methacrylate). Black phosphorus is a very interesting 2D material, whose application have so far been limited by its very high reactivity to oxygen and water. In this respect, we show that electronic-grade black phosphorus flakes, already embedded in a protecting matrix since their exfoliation from the bulk material, are endowed with significant increased stability, and can be further processed into devices without degrading their properties. Creative Commons Attribution license.

Space thermal control development

NASA Technical Reports Server (NTRS)

Hoover, M. J.; Grodzka, P. G.; Oneill, M. J.

1971-01-01

The results of experimental investigations on a number of various phase change materials (PCMs) and PCMs in combination with metals and other materials are reported. The evaluations include the following PCM system performance characteristics: PCM and PCM/filler thermal diffusivities, the effects of long-term thermal cycling, PCM-container compatibility, and catalyst effectiveness and stability. Three PCMs demonstrated performance acceptable enough to be considered for use in prototype aluminum thermal control devices. These three PCMs are lithium nitrate trihydrate with zinc hydroxy nitrate catalyst, acetamide, and myristic acid. Of the fillers tested, aluminum honeycomb filler was found to offer the most increase in system thermal diffusivity.

Magnetorheological materials, method for making, and applications thereof

DOEpatents

Shen, Rui; Yang, Hong; Shafrir, Shai N.; Miao, Chunlin; Wang, Mimi; Mici, Joni; Lambropoulos, John C.; Jacobs, Stephen D.

2014-08-19

A magnetorheological material comprises a magnetic particle and a ceramic material, wherein the magnetorheological material is in a dried form and further wherein a portion of the ceramic material is in the form of a nanocrystalline coating over the entire exterior surface of the magnetic particle and another portion of the ceramic material is in the form of a free nanocrystal. A magnetorheological material comprises a magnetic particle having a ceramic material coating over an external surface thereof as a result of a coating process, and a free nanocrystal of the ceramic material in the form of a residual by-product of the coating process. A sol-gel process for making a magnetorheological product comprises providing a sol of a desired ceramic coating material; combining a desired quantity of carbonyl iron (CI) particles with the sol to coat the CI particles with the ceramic coating material; creating a resulting quantity of nanocrystalline ceramic material-coated CI particles and a quantity of free nanocrystals of the ceramic material; and, drying the resulting quantity of coated CI particles and free nanocrystals to a moisture content equal to or less than 2 wt %.

Effect of inorganic fillers in paper on the adhesion of pressure-sensitive adhesives

Treesearch

Weixu Chen; Xiaoyan Tang; John Considine; Kevin T. Turner

2011-01-01

Inorganic fillers are inexpensive materials used to increase the density, smoothness and other properties of paper that are important for printing. In the current study, the adhesion of pressure-sensitive adhesives (PSAs), a common type of adhesive used in labels and tapes, to papers containing varying amounts and types of fillers is investigated. Papers with three...

Low Temperature, Low Pressure Fabrication of Ultra High Temperature Ceramics (UHTCs)

DTIC Science & Technology

2006-08-01

preceramic polymers that convert by pyrolysis to SiC , SiOC or C. Potential polymeric precursors to ZrB2 and ZrC were not selected, because they were not...limited extent, C/ SiC composite substrates using preceramic and precarbon polymers combined with inert fillers and/or reactive metals. The evolved... SiC is an obvious example for powder mixed with a preceramic polymer binder to achieve the desired low-temperature processing. The polymeric

Electrode carrying wire for GTAW welding

NASA Technical Reports Server (NTRS)

Morgan, Gene E. (Inventor); Dyer, Gerald E. (Inventor)

1990-01-01

A welding torch for gas tungsten arc welding apparatus has a hollow tungsten electrode including a ceramic liner and forms the filler metal wire guide. The wire is fed through the tungsten electrode thereby reducing the size of the torch to eliminate clearance problems which exist with external wire guides. Since the wire is preheated from the tungsten more wire may be fed into the weld puddle, and the wire will not oxidize because it is always within the shielding gas.

Internal wire guide for GTAW welding

NASA Technical Reports Server (NTRS)

Morgan, Gene E. (Inventor); Dyer, Gerald E. (Inventor)

1989-01-01

A welding torch for gas tungsten arc welding apparatus has a filler metal wire guide positioned within the torch, and within the shielding gas nozzle. The wire guide is adjacent to the tungsten electrode and has a ceramic liner through which the wire is fed. This reduces the size of the torch and eliminates the outside clearance problems that exit with external wire guides. Additionally, since the wire is always within the shielding gas, oxidizing of the wire is eliminated.

Improved flywheel materials :

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

Boyle, Timothy J.; Bell, Nelson S; Ehlen, Mark Andrew

As alternative energy generating devices (i.e., solar, wind, etc) are added onto the electrical energy grid (AC grid), irregularities in the available electricity due to natural occurrences (i.e., clouds reducing solar input or wind burst increasing wind powered turbines) will be dramatically increased. Due to their almost instantaneous response, modern flywheel-based energy storage devices can act a mechanical mechanism to regulate the AC grid; however, improved spin speeds will be required to meet the necessary energy levels to balance these green energy variances. Focusing on composite flywheels, we have investigated methods for improving the spin speeds based on materials needs.more » The so-called composite flywheels are composed of carbon fiber (C-fiber), glass fiber, and a glue (resin) to hold them together. For this effort, we have focused on the addition of fillers to the resin in order to improve its properties. Based on the high loads required for standard meso-sized fillers, this project investigated the utility of ceramic nanofillers since they can be added at very low load levels due to their high surface area. The impact that TiO2 nanowires had on the final strength of the flywheel material was determined by a three-point-bend test. The results of the introduction of nanomaterials demonstrated an increase in strength of the flywheels C-fiber-resin moiety, with an upper limit of a 30% increase being reported. An analysis of the economic impact concerning the utilization of the nanowires was undertaken and after accounting for new-technology and additional production costs, return on improved-nanocomposite investment was approximated at 4-6% per year over the 20-year expected service life. Further, it was determined based on the 30% improvement in strength, this change may enable a 20-30% reduction in flywheel energy storage cost ($/kW-h).« less

Filler/ Polycarbosilane Systems as CMC Matrix Precursors

NASA Technical Reports Server (NTRS)

Hurwitz, Frances I.

1998-01-01

Pyrolytic conversion of polymeric precursors to ceramics is accompanied by loss of volatiles and large volume changes. Infiltration of a low viscosity polymer into a fiber preform will fill small spaces within fiber tows by capillary forces, but create large matrix cracks within large, intertow areas. One approach to minimizing shrinkage and reducing the number of required infiltration cycles is to use particulate fillers. In this study, Starfire allylhydridopolycarbosilane (AHPCS) was blended with a silicon carbide powder, with and without dispersant, using shear mixing. The polymer and polymer/particle interactions were characterized using nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis and rheometry. Polymer/particulate slurries and suspensions were used to infiltrate a figidized preform of an eight ply five harness satin CG Nicalon fiber having a dual layer BN/SiC interface coating, and the resulting composites characterized by optical and scanning electron microscopy.

Catalytic bipolar interconnection plate for use in a fuel cell

DOEpatents

Lessing, Paul A.

1996-01-01

A bipolar interconnection plate for use between adjacent fuel cell units in a stacked fuel cell assembly. Each plate is manufactured from an intermetallic composition, examples of which include NiAl or Ni.sub.3 Al which can catalyze steam reforming of hydrocarbons. Distributed within the intermetallic structure of the plate is a ceramic filler composition. The plate includes a first side with gas flow channels therein and a second side with fuel flow channels therein. A protective coating is applied to the first side, with exemplary coatings including strontium-doped or calcium-doped lanthanum chromite. To produce the plate, Ni and Al powders are combined with the filler composition, compressed at a pressure of about 10,000-30,000 psi, and heated to about 600.degree.-1000.degree. C. The coating is then applied to the first side of the completed plate using liquid injection plasma deposition or other deposition techniques.

Catalytic bipolar interconnection plate for use in a fuel cell

DOEpatents

Lessing, P.A.

1996-03-05

A bipolar interconnection plate is described for use between adjacent fuel cell units in a stacked fuel cell assembly. Each plate is manufactured from an intermetallic composition, examples of which include NiAl or Ni{sub 3}Al which can catalyze steam reforming of hydrocarbons. Distributed within the intermetallic structure of the plate is a ceramic filler composition. The plate includes a first side with gas flow channels therein and a second side with fuel flow channels therein. A protective coating is applied to the first side, with exemplary coatings including strontium-doped or calcium-doped lanthanum chromite. To produce the plate, Ni and Al powders are combined with the filler composition, compressed at a pressure of about 10,000--30,000 psi, and heated to about 600--1000 C. The coating is then applied to the first side of the completed plate using liquid injection plasma deposition or other deposition techniques. 6 figs.

Composites of ionic liquid and amine-modified SAPO 34 improve CO2 separation of CO2-selective polymer membranes

NASA Astrophysics Data System (ADS)

Hu, Leiqing; Cheng, Jun; Li, Yannan; Liu, Jianzhong; Zhang, Li; Zhou, Junhu; Cen, Kefa

2017-07-01

Mixed matrix membranes with ionic liquids and molecular sieve particles had high CO2 permeabilities, but CO2 separation from small gas molecules such as H2 was dissatisfied because of bad interfacial interaction between ionic liquid and molecular sieve particles. To solve that, amine groups were introduced to modify surface of molecular sieve particles before loading with ionic liquid. SAPO 34 was adopted as the original filler, and four mixed matrix membranes with different fillers were prepared on the outer surface of ceramic hollow fibers. Both surface voids and hard agglomerations disappeared, and the surface became smooth after SAPO 34 was modified by amine groups and ionic liquid [P66614][2-Op]. Mixed matrix membranes with composites of amine-modified SAPO 34 and ionic liquid exhibited excellent CO2 permeability (408.9 Barrers) and CO2/H2 selectivity (22.1).

STS-114: Discovery Day 6 Post MMT Meeting

NASA Technical Reports Server (NTRS)

2005-01-01

Wayne Hale, Space Shuttle Deputy Program Manager and Steve Poulos, Orbiter Program Manager, discuss the damage assessment from the tiles that came off the Space Shuttle Discovery during launch. Poulos presents charts and discusses in detail the following topics: 1) Composite Tile Damage/Gap Filler Sites Evaluation; 2) Protruding Ceramic Shim Aft of the Nose Landing Gear Door (NLGD); 3) Protruding Chine Gap Filler; 4) RH NLGD Tile Damage; 5) RH NLGD Damage Analysis; 6) Left Wing Tile Damage; 7) Comparison of Ground Test Results vs. FD5 Focused Inspection; 8) Current Status: Focused Inspection 721L07-01 ITVC FD5 Image of Panel 7L Apex 9) Current Status: Focused Inspection Lower Panel 7L721L07-02; 10) Current Status Focused Inspection 721L10-02 Lower Panel 10L Close-up view; and 11) Window 1 Blanket. The presentation ends with a question and answer period from the news media.

Laser Transmission Welding of CFRTP Using Filler Material

NASA Astrophysics Data System (ADS)

Berger, Stefan; Schmidt, Michael

In the automotive industry the increasing environmental awareness is reflected through consistent lightweight construction. Especially the use of carbon fiber reinforced thermoplastics (CFRTP) plays an increasingly important role. Accordingto the material substitution, the demand for adequate joining technologies is growing. Therefore, laser transmission welding with filler material provides a way to combine two opaque joining partners by using process specific advantages of the laser transmission welding process. After introducing the new processing variant and the used experimental setup, this paper investigates the process itselfand conditions for a stable process. The influence of the used process parameters on weld quality and process stability is characterized by tensile shear tests. The successfully performed joining of PA 6 CF 42 organic sheets using natural PA 6 as filler material underlines the potential of the described joining method for lightweight design and other industrial applications.

Ceramic electrolyte coating and methods

DOEpatents

Seabaugh, Matthew M [Columbus, OH; Swartz, Scott L [Columbus, OH; Dawson, William J [Dublin, OH; McCormick, Buddy E [Dublin, OH

2007-08-28

Aqueous coating slurries useful in depositing a dense coating of a ceramic electrolyte material (e.g., yttrium-stabilized zirconia) onto a porous substrate of a ceramic electrode material (e.g., lanthanum strontium manganite or nickel/zirconia) and processes for preparing an aqueous suspension of a ceramic electrolyte material and an aqueous spray coating slurry including a ceramic electrolyte material. The invention also includes processes for depositing an aqueous spray coating slurry including a ceramic electrolyte material onto pre-sintered, partially sintered, and unsintered ceramic substrates and products made by this process.

The Microstructural Evolution of Vacuum Brazed 1Cr18Ni9Ti Using Various Filler Metals

PubMed Central

Chen, Yunxia; Cui, Haichao; Lu, Binfeng; Lu, Fenggui

2017-01-01

The microstructures and weldability of a brazed joint of 1Cr18Ni9Ti austenitic stainless steel with BNi-2, BNi82CrSiBFe and BMn50NiCuCrCo filler metals in vacuum were investigated. It can be observed that an interdiffusion region existed between the filler metal and the base metal for the brazed joint of Ni-based filler metals. The width of the interdiffusion region was about 10 μm, and the microstructure of the brazed joint of BNi-2 filler metal was dense and free of obvious defects. In the case of the brazed joint of BMn50NiCuCrCo filler metal, there were pits, pores and crack defects in the brazing joint due to insufficient wettability of the filler metal. Crack defects can also be observed in the brazed joint of BNi82CrSiBFe filler metal. Compared with BMn50NiCuCrCo and BNi82CrSiBFe filler metals, BNi-2 filler metal is the best material for 1Cr18Ni9Ti austenitic stainless steel vacuum brazing because of its distinct weldability. PMID:28772745

Effect of the coating material on root dentin remineralization in vitro.

PubMed

Shiiya, Toru; Tomiyama, Kiyoshi; Iizuka, Junko; Hasegawa, Haruhiko; Kuramochi, Erika; Fujino, Fukue; Ohashi, Katsura; Nihei, Tomotaro; Teranaka, Toshio; Mukai, Yoshiharu

2014-10-01

A fluoride-releasing coating material containing surface pre-reacted glass-ionomer (S-PRG) filler has become commercially available. However, there has been no detailed investigation of its remineralization effects at various tooth surface regions. The remineralization effects of S-PRG filler-containing coating material at different sites of demineralized dentin surfaces in vitro were evaluated. Baseline lesions were prepared on bovine root dentin surfaces by immersion in demineralization buffer and divided into four groups: (B)--baseline lesion; (P)--S-PRG filler-containing material; (V)--S-PRG filler-free coating material as negative control; and (X)--resin-modified glass- ionomer as positive control. Material was applied to half the lesion surface, then P, V and X were remineralized in a gel system. Mineral profiles, integrated mineral loss (IML) and lesion depth (LD) at four regions, i.e. 1--exposed dentin surface adjacent to the material; 2--at a distance from the material; 3--beneath the material near to the edge; and 4--at a distance from the edge, were analyzed by transversal microradiography. Data were analyzed using ANOVA and Games-Howell test with α = 0.05. B showed typical artificial demineralized lesion. The IMLs of V, P and X at regions 1 and 2, and P and X at region 3 were significantly lower than that of B, however, those of V at region 3 and the other three groups at region 4 were not significantly different from that of B. At region 1, P and X showed significantly lower IMLs than V. At region 2, the IML of X showed significantly lower IML than V. There was no significant difference between P and X. The LD values of V, P and X at all regions were not significantly different from that of B. Fluoride, strontium and silicate ions released from the S-PRG filler would provide a favorable environment for remineralization of the demineralized dentin in P.

Effect of Mg content on the thermal stability and mechanical behaviour of PLLA/Mg composites processed by hot extrusion.

PubMed

Cifuentes, S C; Lieblich, M; López, F A; Benavente, R; González-Carrasco, J L

2017-03-01

In the field of bioabsorbable composites for biomedical applications, extrusion has been employed as a method to prepare homogeneous blends of polymeric matrices with bioactive ceramic fillers. In this work, the suitability of processing poly-l-lactic acid/Magnesium (PLLA/Mg) composites by hot extrusion has been assessed by a systematic characterization of PLLA/Mg composites containing different amounts of Mg particles up to 7wt%. The results show that extrusion causes a reduction of almost 20% in the viscosity average molecular weight of PLLA, which further decreases with increasing Mg content. Extrusion gave always rise to a homogeneous distribution of Mg particles within the PLLA matrix. This composite processing was not compromised by the degradation of the polymeric matrix because the processing temperature was always below the onset degradation temperature. In the processing conditions employed in the present work, degradation of the composite slightly increases as more Mg is added up to 5wt%, but is very high at 7wt%. This was also evident from the mechanical behaviour, so that Mg particles improved the stiffness and compression strength of neat PLLA until 5wt% of Mg content, which dropped drastically when the material had 7wt% of Mg. The filler strengthening factor decreases with the increment in Mg content. In order to obtain an optimised contribution of Mg particles, a balance between thermal degradation and mechanical resistance of PLLA must be achieved. Copyright © 2016 Elsevier B.V. All rights reserved.

DC bias effect on alternating current electrical conductivity of poly(ethylene terephthalate)/alumina nanocomposites

NASA Astrophysics Data System (ADS)

Nikam, Pravin N.; Deshpande, Vineeta D.

2016-05-01

Polymer nanocomposites based on metal oxide (ceramic) nanoparticles are a new class of materials with unique properties and designed for various applications such as electronic device packaging, insulation, fabrication and automotive industries. Poly(ethylene terephthalate) (PET)/alumina (Al2O3) nanocomposites with filler content between 1 wt% and 5 wt% were prepared by melt compounding method using co-rotating twin screw extruder and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and precision LCR meter techniques. The results revealed that proper uniform dispersion at lower content up to 2 wt% of nano-alumina observed by using TEM. Aggregation of nanoparticles was observed at higher content of alumina examined by using SEM and TEM. The frequency dependences of the alternating current (AC) conductivity (σAC) of PET/alumina nanocomposites on the filler content and DC bias were investigated in the frequency range of 20Hz - 1MHz. The results showed that the AC and direct current (DC) conductivity increases with increasing DC bias and nano-alumina content upto 3 wt%. It follows the Jonscher's universal power law of solids. It revealed that σAC of PET/alumina nanocomposites can be well characterized by the DC conductivity (σDC), critical frequency (ωc), critical exponent of the power law (s). Roll of DC bias potential led to an increase of DC conductivity (σDC) due to the creation of additional conducting paths with the polymer nanocomposites and percolation behavior achieved through co-continuous morphology.

Study on mechanical and physical properties of composite materials with recycled PET as fillers for paving block application

NASA Astrophysics Data System (ADS)

Wicaksono, Sigit Tri; Ardhyananta, Hosta; Rasyida, Amaliya

2018-04-01

Base on Sidoarjo's goverment data, there was more than 4000 metric ton perday of waste that has been accumulated during 2016. More than 10 percent from overall waste is plastics. In accordance with the Indonesia government regulation, "Indonesia clean from waste" by 2020 through 3R (Reduce, Reuse and Recycle) program, we have been focusing research on how to reduce the accumulation of the plastics waste in Sidoarjo by processing it become a new product. In this research, we have made the plastic waste of PET bottle as additional fillers or agregates of composite material for construction application as a paving block. The composition of PET plastic used as fillers is vary from 0, 10, 20, 30, 40 and 50% from total volume of agregates. The ratio of cement binder to sands agregate is 1:3. The specimens were characterized its mechanical and physical properties by using flexural testing, compressive testing, density and water absorbance measurement. The results show that the mechanical (flexural and compressive) properties of composite materials is increased significantly by increasing PET fillers up to 20%, however it was decreased when PET content more than 20%. But, both the density and water absobance of specimens are decreased by increasing of PET fillers.

Quantification of cell response to polymeric composites using a two-dimensional gradient platform.

PubMed

Lin, Nancy J; Hu, Haiqing; Sung, Lipin; Lin-Gibson, Sheng

2009-07-01

A simple and straightforward screening process to assess the toxicity and corresponding cell response of dental composites would be useful prior to extensive in vitro or in vivo characterization. To this end, gradient composite samples were prepared with variations in filler content/type and in degree of conversion (DC). The DC was determined using near infrared spectroscopy (NIR), and the surface morphology was evaluated by laser scanning confocal microscopy (LSCM). RAW 264.7 macrophage-like cells were cultured directly on the composite gradient samples, and cell viability, density, and area were measured at 24 h. All three measures of cell response varied as a function of material properties. For instance, compositions with higher filler content had no reduction in cell viability or cell density, even at low conversions of 52%, whereas significant decreases in viability and density were present when the filler content was 35% or below (by mass). The overall results demonstrate the complexity of the cell-material interactions, with properties including DC, filler type, filler mass ratio, and surface morphology influencing the cell response. The combinatorial approach described herein enables simultaneous screening of multiple compositions and material properties, providing a more thorough characterization of cell response for the improved selection of biocompatible composite formulations and processing conditions.

Nanostructured conductive polymeric materials

NASA Astrophysics Data System (ADS)

Al-Saleh, Mohammed H.

Conductive polymer composites (CPCs) are a suitable alternative to metals in many applications due to their light-weight, corrosion resistance, low cost, ease of processing and design flexibility. CPCs have been formulated using different types of conductive fillers. In this PhD thesis, the focus is on CPCs for electrostatic discharge (ESD) protection and electromagnetic interference (EMI) attenuation. Despite the versatility of conductive fillers, carbon black (CB) has been the dominant filler to make CPCs for ESD protection applications because CB/polymer composites have a cost advantage over all other CPCs. For EMI shielding, stainless steel fibres and metal coated fibers are the preferred fillers, however CPCs made of those fibers are not the dominant EMI shielding materials. Metal coated and polymer plated polymers are the most widely used EMI shielding options. The limited use of CPCs in the EMI shielding market is because the high filler loading required to formulate a composite with an adequate level of shielding remarkably increases the composite price. In order to increase the competitiveness of CPCs, percolation threshold should be minimized as much as possible and composites with high EMI shielding capabilities at low filler loading should be formulated because all conductive fillers are expensive compared to polymers. In this thesis, two different methodologies to reduce percolation threshold in CPCs have been successfully developed and a CPC with exceptional EMI shielding capability has been formulated using copper nanowires as conductive filler. The first percolation threshold reduction technique is based on the selective localization of CB at the interface of immiscible polymer blend. The technique requires adding a copolymer that prefers the blend's interface and for which CB nanoparticles has the highest affinity. The second method is based on producing a CPC powder and then using this powder as a conductive filler to produce composite by dry mixing with pure polymer powder followed by compression molding. The EMI shielding material was developed using copper nanowires. CuNW/Polystyrene composites exhibit EMI shielding effectiveness exceeding that of metal microfillers and carbon nanotube/polymer composites and approaching that of coating techniques have been formulated by solution processing and dry mixing.

Theoretical and Numerical Approaches for Determining the Reflection and Transmission Coefficients of OPEFB-PCL Composites at X-Band Frequencies

PubMed Central

Ahmad, Ahmad F.; Abbas, Zulkifly; Obaiys, Suzan J.; Ibrahim, Norazowa; Hashim, Mansor; Khaleel, Haider

2015-01-01

Bio-composites of oil palm empty fruit bunch (OPEFB) fibres and polycaprolactones (PCL) with a thickness of 1 mm were prepared and characterized. The composites produced from these materials are low in density, inexpensive, environmentally friendly, and possess good dielectric characteristics. The magnitudes of the reflection and transmission coefficients of OPEFB fibre-reinforced PCL composites with different percentages of filler were measured using a rectangular waveguide in conjunction with a microwave vector network analyzer (VNA) in the X-band frequency range. In contrast to the effective medium theory, which states that polymer-based composites with a high dielectric constant can be obtained by doping a filler with a high dielectric constant into a host material with a low dielectric constant, this paper demonstrates that the use of a low filler percentage (12.2%OPEFB) and a high matrix percentage (87.8%PCL) provides excellent results for the dielectric constant and loss factor, whereas 63.8% filler material with 36.2% host material results in lower values for both the dielectric constant and loss factor. The open-ended probe technique (OEC), connected with the Agilent vector network analyzer (VNA), is used to determine the dielectric properties of the materials under investigation. The comparative approach indicates that the mean relative error of FEM is smaller than that of NRW in terms of the corresponding S21 magnitude. The present calculation of the matrix/filler percentages endorses the exact amounts of substrate utilized in various physics applications. PMID:26474301

Preparation of Ultraviolet Curing Type Silicone Rubbers Containing Mesoporous Silica Fillers.

PubMed

Abdullah, Nawfel; Hossain, Md Shahriar A; Fatehmulla, Amanullah; Farooq, Wazirzada Aslam; Islam, Md Tofazzal; Miyamoto, Nobuyoshi; Bando, Yoshio; Kamachi, Yuichiro; Malgras, Victor; Yamauchi, Yusuke; Suzuki, Norihiro

2018-01-01

Here we have been focusing on mesoporous silica (MPS) as inorganic filler material to improve the mechanical strength of silicone rubbers. The MPS particles are more effective in reducing the coefficient of thermal expansion (CTE) and hardening silicone rubber composites when compared to commercially available nonporous silica particles. In this study, we utilize ultraviolet curing type silicone rubbers and prepare MPS composites according to a simple single-step method. From an industrial viewpoint, simplifying the fabrication processes is critical. The thermal stability and mechanical strength are examined in detail in order to showcase the effectiveness of MPS particles as filler materials.

Modelling and operation strategies of DLR's large scale thermocline test facility (TESIS)

NASA Astrophysics Data System (ADS)

Odenthal, Christian; Breidenbach, Nils; Bauer, Thomas

2017-06-01

In this work an overview of the TESIS:store thermocline test facility and its current construction status will be given. Based on this, the TESIS:store facility using sensible solid filler material is modelled with a fully transient model, implemented in MATLAB®. Results in terms of the impact of filler site and operation strategies will be presented. While low porosity and small particle diameters for the filler material are beneficial, operation strategy is one key element with potential for optimization. It is shown that plant operators have to ponder between utilization and exergetic efficiency. Different durations of the charging and discharging period enable further potential for optimizations.

Comparative characterization of a novel cad-cam polymer-infiltrated-ceramic-network

PubMed Central

Pascual, Agustín; Camps, Isabel; Grau-Benitez, María

2015-01-01

Background The field of dental ceramics for CAD-CAM is enriched with a new innovative material composition having a porous three-dimensional structure of feldspathic ceramic infiltrated with acrylic resins.The aim of this study is to determine the mechanical properties of Polymer-Infiltrated-Ceramic-Network (PICN) and compare its performance with other ceramics and a nano-ceramic resin available for CAD-CAM systems. Material and Methods In this study a total of five different materials for CAD-CAM were investigated. A polymer-infiltrated ceramic (Vita Enamic), a nano-ceramic resin (Lava Ultimate), a feldspathic ceramic (Mark II), a lithium disilicate ceramic (IPS-e max CAD) and finally a Leucite based ceramic (Empress - CAD). From CAD-CAM blocks, 120 bars (30 for each material cited above) were cut to measure the flexural strength with a three-point-bending test. Strain at failure, fracture stress and Weibull modulus was calculated. Vickers hardness of each material was also measured. Results IPS-EMAX presents mechanical properties significantly better from the other materials studied. Its strain at failure, flexural strength and hardness exhibited significantly higher values in comparison with the others. VITA ENAMIC and LAVA ULTIMATE stand out as the next most resistant materials. Conclusions The flexural strength, elastic modulus similar to a tooth as well as having less hardness than ceramics make PICN materials an option to consider as a restorative material. Key words:Ceramic infiltrated with resin, CAD-CAM, Weibull modulus, flexural strength, micro hardness. PMID:26535096

High-k 3D-barium titanate foam/phenolphthalein poly(ether sulfone)/cyanate ester composites with frequency-stable dielectric properties and extremely low dielectric loss under reduced concentration of ceramics

NASA Astrophysics Data System (ADS)

Zheng, Longhui; Yuan, Li; Guan, Qingbao; Liang, Guozheng; Gu, Aijuan

2018-01-01

Higher dielectric constant, lower dielectric loss and better frequency stability have been the developing trends for high dielectric constant (high-k) materials. Herein, new composites have been developed through building unique structure by using hyperbranched polysiloxane modified 3D-barium titanate foam (BTF) (BTF@HSi) as the functional fillers and phenolphthalein poly(ether sulfone) (cPES)/cyanate ester (CE) blend as the resin matrix. For BTF@HSi/cPES/CE composite with 34.1 vol% BTF, its dielectric constant at 100 Hz is as high as 162 and dielectric loss is only 0.007; moreover, the dielectric properties of BTF@HSi/cPES/CE composites exhibit excellent frequency stability. To reveal the mechanism behind these attractive performances of BTF@HSi/cPES/CE composites, three kinds of composites (BTF/CE, BTF/cPES/CE, BTF@HSi/CE) were prepared, their structure and integrated performances were intensively investigated and compared with those of BTF@HSi/cPES/CE composites. Results show that the surface modification of BTF is good for preparing composites with improved thermal stability; while introducing flexible cPES to CE is beneficial to fabricate composites with good quality through effectively blocking cracks caused by the stress concentration, and then endowing the composites with good dielectric properties at reduced concentration of ceramics.

High voltage photoconductive switch package

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

Caporaso, George J.

2016-11-22

A photoconductive switch having a wide bandgap material substrate between opposing electrodes, and a doped dielectric filler that is in contact with both the electrodes and the substrate at the triple point. The dielectric filler material is doped with a conductive material to make it partially or completely conducting, to minimize the field enhancement near the triple point both when the substrate is not conducting in the "off" state and when the substrate is rendered conducting by radiation in the "on" state.

Effect of Storage in Distilled Water for Three Months on the Antimicrobial Properties of Poly(methyl methacrylate) Denture Base Material Doped with Inorganic Filler

PubMed Central

Chladek, Grzegorz; Basa, Katarzyna; Mertas, Anna; Pakieła, Wojciech; Żmudzki, Jarosław; Bobela, Elżbieta; Król, Wojciech

2016-01-01

The colonization of poly(methyl methacrylate) (PMMA) denture base materials by pathogenic microorganisms is a major problem associated with the use of prostheses, and the incorporation of antimicrobial fillers is a method of improving the antimicrobial properties of these materials. Numerous studies have demonstrated the initial in vitro antimicrobial effectiveness of this type of material; however, reports demonstrating the stability of these fillers over longer periods are not available. In this study, silver sodium hydrogen zirconium phosphate was introduced into the powder component of a PMMA denture base material at concentrations of 0.25%, 0.5%, 1%, 2%, 4%, and 8% (w/w). The survival rates of the gram-positive bacterium Staphylococcus aureus, gram-negative bacterium Escherichia coli and yeast-type fungus Candida albicans were established after fungal or bacterial suspensions were incubated with samples that had been previously stored in distilled water. Storage over a three-month period led to the progressive reduction of the initial antimicrobial properties. The results of this study suggest that additional microbiological tests should be conducted for materials that are treated with antimicrobial fillers and intended for long-term use. Future long-term studies of the migration of silver ions from the polymer matrix and the influence of different media on this ion emission are required. PMID:28773451

Revisit to three-dimensional percolation theory: Accurate analysis for highly stretchable conductive composite materials

PubMed Central

Kim, Sangwoo; Choi, Seongdae; Oh, Eunho; Byun, Junghwan; Kim, Hyunjong; Lee, Byeongmoon; Lee, Seunghwan; Hong, Yongtaek

2016-01-01

A percolation theory based on variation of conductive filler fraction has been widely used to explain the behavior of conductive composite materials under both small and large deformation conditions. However, it typically fails in properly analyzing the materials under the large deformation since the assumption may not be valid in such a case. Therefore, we proposed a new three-dimensional percolation theory by considering three key factors: nonlinear elasticity, precisely measured strain-dependent Poisson’s ratio, and strain-dependent percolation threshold. Digital image correlation (DIC) method was used to determine actual Poisson’s ratios at various strain levels, which were used to accurately estimate variation of conductive filler volume fraction under deformation. We also adopted strain-dependent percolation threshold caused by the filler re-location with deformation. When three key factors were considered, electrical performance change was accurately analyzed for composite materials with both isotropic and anisotropic mechanical properties. PMID:27694856

Abrasion-Resistant Coating for Flexible Insulation

NASA Technical Reports Server (NTRS)

Mui, D.; Headding, R. E.

1986-01-01

Ceramic coating increases durability and heat resistance of flexible high-temperature insulation. Coating compatible with quartz-fabric insulation allowing it to remain flexible during and after repeated exposures to temperatures of 1,800 degree F (982 degree C). Prevents fabric from becoming brittle while increasing resistance to aerodynamic abrasion and loading. Coating consists of penetrating precoat and topcoat. Major ingredients high-purity colloidal silica binder and ground silica filler, which ensure stability and compatibility with fabric at high temperatures. Both precoat and topcoat cured at room temperature.

Needs assessment for nondestructive testing and materials characterization for improved reliability in structural ceramics for heat engines

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

Johnson, D.R.; McClung, R.W.; Janney, M.A.

1987-08-01

A needs assessment was performed for nondestructive testing and materials characterization to achieve improved reliability in ceramic materials for heat engine applications. Raw materials, green state bodies, and sintered ceramics were considered. The overall approach taken to improve reliability of structural ceramics requires key inspections throughout the fabrication flowsheet, including raw materials, greed state, and dense parts. The applications of nondestructive inspection and characterization techniques to ceramic powders and other raw materials, green ceramics, and sintered ceramics are discussed. The current state of inspection technology is reviewed for all identified attributes and stages of a generalized flowsheet for advanced structuralmore » ceramics, and research and development requirements are identified and listed in priority order. 164 refs., 3 figs.« less

Optimization and Characterization of Preceramic Inks for Direct Ink Writing of Ceramic Matrix Composite Structures

PubMed Central

Maden, Halide Selin; Wahl, Larissa; Baliello, Andrea

2018-01-01

In a previous work, an ink based on a preceramic polymer, SiC fillers, and chopped carbon fibers was proposed for the production of Ceramic Matrix Composite (CMC) structures by Direct Ink Writing (DIW) and subsequent pyrolysis. Thanks to the shear stresses generated at the nozzle tip during extrusion, carbon fibers can be aligned along the printing direction. Fumed silica was added to the ink in order to enhance its rheological properties; however, the printed structures still showed some deformation in the Z direction. In this work, a second ink was successfully developed to limit deformation and at the same time avoid the addition of fumed silica, which limited the potential temperature of application of the composites. Instead, the positive role of the preceramic polymer on the ink rheology was exploited by increasing its concentration in the ink. Rheological characterization carried out on both inks confirmed that they possessed Bingham shear thinning behavior and fast viscosity recovery. Single filaments with different diameters (~310 µm and ~460 µm) were produced with the latter ink by DIW and subsequent pyrolysis. Tested under a four-point flexural test, the filaments showed a mean flexural strength above 30 MPa, graceful failure, and fiber pull-out. The results of this work suggest that CMC components can effectively be fabricated via DIW of a preceramic ink with embedded short fibers; the preceramic polymer is able to provide the desired rheology for the process and to develop a dense matrix capable of incorporating both fibers and ceramic particles, whereas the fibers addition contributes to an increase of the fracture toughness of the material and to the development of a graceful failure mode. PMID:29597310

Optimization and Characterization of Preceramic Inks for Direct Ink Writing of Ceramic Matrix Composite Structures.

PubMed

Franchin, Giorgia; Maden, Halide Selin; Wahl, Larissa; Baliello, Andrea; Pasetto, Marco; Colombo, Paolo

2018-03-28

In a previous work, an ink based on a preceramic polymer, SiC fillers, and chopped carbon fibers was proposed for the production of Ceramic Matrix Composite (CMC) structures by Direct Ink Writing (DIW) and subsequent pyrolysis. Thanks to the shear stresses generated at the nozzle tip during extrusion, carbon fibers can be aligned along the printing direction. Fumed silica was added to the ink in order to enhance its rheological properties; however, the printed structures still showed some deformation in the Z direction. In this work, a second ink was successfully developed to limit deformation and at the same time avoid the addition of fumed silica, which limited the potential temperature of application of the composites. Instead, the positive role of the preceramic polymer on the ink rheology was exploited by increasing its concentration in the ink. Rheological characterization carried out on both inks confirmed that they possessed Bingham shear thinning behavior and fast viscosity recovery. Single filaments with different diameters (~310 µm and ~460 µm) were produced with the latter ink by DIW and subsequent pyrolysis. Tested under a four-point flexural test, the filaments showed a mean flexural strength above 30 MPa, graceful failure, and fiber pull-out. The results of this work suggest that CMC components can effectively be fabricated via DIW of a preceramic ink with embedded short fibers; the preceramic polymer is able to provide the desired rheology for the process and to develop a dense matrix capable of incorporating both fibers and ceramic particles, whereas the fibers addition contributes to an increase of the fracture toughness of the material and to the development of a graceful failure mode.

Hydrodynamic parameters of mesh fillers relevant to miniature regenerative cryocoolers

NASA Astrophysics Data System (ADS)

Landrum, E. C.; Conrad, T. J.; Ghiaasiaan, S. M.; Kirkconnell, Carl S.

2010-06-01

Directional hydrodynamic parameters of two fine-mesh porous materials that are suitable for miniature regenerative cryocoolers were studied under steady and oscillating flows of helium. These materials included stacked discs of #635 stainless steel (wire diameter of 20.3 μm) and #325 phosphor bronze (wire diameter of 35.6 μm) wire mesh screens, which are among the commercially available fillers for use in small-scale regenerators and heat exchangers, respectively. Experiments were performed in test sections in which pressure variations across these fillers, in the axial and lateral (radial) directions, were measured under steady and oscillatory flows. The directional permeability and Forchheimer's inertial coefficient were then obtained by using a Computational Fluid Dynamics (CFD)-assisted method. The oscillatory flow experiments covered a frequency range of 50-200 Hz. The results confirmed the importance of anisotropy in the mesh screen fillers, and indicated differences between the directional hydrodynamic resistance parameters for steady and oscillating flow regimes.

Influence of glass particle size of resin cements on bonding to glass ceramic: SEM and bond strength evaluation.

PubMed

Valentini, Fernanda; Moraes, Rafael R; Pereira-Cenci, Tatiana; Boscato, Noéli

2014-05-01

This study investigated the effect of the filler particle size (micron or submicron) of experimental resin cements on the microtensile bond strength to a glass-ceramic pretreated with hydrofluoric acid (HFA) etching or alumina airborne-particle abrasion (AA). Cements were obtained from a Bis-GMA/TEGDMA mixture filled with 60 mass% micron-sized (1 ± 0.2 µm) or submicron-sized (180 ± 30 µm) Ba-Si-Al glass particles. Ceramic blocks (PM9; VITA) were treated with 10% HFA for 60 s or AA for 15 s. Silane and adhesive were applied. Ceramic blocks were bonded to resin composite blocks (Z250; 3M ESPE) using one of the cements. Bonded specimens were sectioned into beams (n = 20/group) and subjected to microtensile bond strength tests. Data were analyzed using ANOVA and Student-Newman-Keuls' tests (5%). Failure modes were classified under magnification. Morphologies of the treated ceramic surfaces and bonded interfaces were evaluated by scanning electron microscopy. The HFA-submicron group had lower bond strengths than the other groups. All AA-submicron specimens debonded prematurely. Mixed failures were predominant for HFA groups, whereas interfacial failures predominated for AA groups. SEM revealed a honeycomb-like aspect in the HFA-treated ceramic, whereas the AA-treated groups showed an irregular retentive pattern. Continuity of cement infiltration along the bonded interface was more uniform for HFA-treated compared to AA-treated specimens. Cracks toward the bulk of the ceramic were observed in AA-treated specimens. Particle size significantly influenced the ceramic bond strength, whereas surface treatment had a minor effect. Copyright © 2014 Wiley Periodicals, Inc.

Fillers: from the past to the future.

PubMed

Glogau, Richard G

2012-06-01

Modern medical use of injectable soft-tissue augmentation fillers has evolved from the introduction of bovine collage implants to an array of synthesized materials in the current domestic and foreign markets. The concept of augmentation has moved from simple lines, scars, and wrinkles to revolumizing the aging face. A brief overview of the past, present, and future injectable fillers is presented. Copyright © 2012 Elsevier Inc. All rights reserved.

Characterization of Morphology and Composition of Inorganic Fillers in Dental Alginates

PubMed Central

Guiraldo, Ricardo Danil; Berger, Sandrine Bittencourt; Consani, Rafael Leonardo Xediek; Consani, Simonides; de Carvalho, Rodrigo Varella; Lopes, Murilo Baena; Meneghel, Luciana Lira; da Silva, Fabiane Borges; Sinhoreti, Mário Alexandre Coelho

2014-01-01

Energy dispersive X-ray spectroscopy microanalysis (EDX), scanning electron microscopy (SEM), and Archimedes' Principle were used to determine the characteristics of inorganic filler particles in five dental alginates, including Cavex ColorChange (C), Hydrogum 5 (H5), Hydrogum (H), Orthoprint (O), and Jeltrate Plus (JP). The different alginate powders (0.5 mg) were fixed on plastic stubs (n = 5) and sputter coated with carbon for EDX analysis, then coated with gold, and observed using SEM. Volume fractions were determined by weighing a sample of each material in water before and after calcining at 450°C for 3 h. The alginate materials were mainly composed of silicon (Si) by weight (C—81.59%, H—79.89%, O—78.87%, H5—77.95%, JP—66.88%, wt). The filler fractions in volume (vt) were as follows: H5—84.85%, JP—74.76%, H—70.03%, O—68.31%, and C—56.10%. The tested materials demonstrated important differences in the inorganic elemental composition, filler fraction, and particle morphology. PMID:25165690

FISSILE MATERIAL AND FUEL ELEMENTS FOR NEUTRONIC REACTORS

DOEpatents

Shaner, B.E.

1961-08-15

The fissile material consists of about 64 to 70% (weight) zirconium dioxide, 15 to 19% uranium dioxide, and 8 to 17% calcium oxide. The fissile material is formed into sintered composites which are disposed in a compartmented fuel element, comprising essentially a flat filler plate having a plurality of compartments therein, enclosed in cladding plates of the same material as the filler plate. The resultant fuel has good resistance to corrosion in high temperature pressurized water, good dimensional stability to elevated temperatures, and good resistance to thermal shock. (AEC)

Testing of felt-ceramic materials for combustor applications

NASA Technical Reports Server (NTRS)

Venkat, R. S.; Roffe, G.

1983-01-01

The feasibility of using composite felt ceramic materials as combustor liners was experimentally studied. The material consists of a porous felt pad sandwiched between a layer of ceramic and one of solid metal. Flat, rectangular test panels, which encompassed several design variations of the basic composite material, were tested, two at a time, in a premixed gas turbine combustor as sections of the combustor wall. Tests were conducted at combustor inlet conditions of 0.5 MPa and 533 K with a reference velocity of 25 m/s. The panels were subjected to a hot gas temperature of 2170 K with 1% of the total airflow used to film cool the ceramic surface of the test panel. In general, thin ceramic layers yield low ceramic stress levels with high felt ceramic interface temperatures. On the other hand, thick ceramic layers result in low felt ceramic interface temperatures but high ceramic stress levels. Extensive thermal cycling appears to cause material degradation, but for a limited number of cycles, the survivability of felt ceramic materials, even under extremely severe combustor operating conditions, was conclusively demonstrated.

Characteristics of nitrogen removal and microbial community in biofilm system via combination of pretreated lignocellulosic carriers and various conventional fillers.

PubMed

Zhao, Jing; Feng, Lijuan; Dai, Jincheng; Yang, Guangfeng; Mu, Jun

2017-12-01

Each kind of conventional plastic filler (polyurethane filler, SPR-1 suspension filler, TA-II elastic filler and sphere filler) coupled with alkaline pretreated corncob (A.H.corncob) was applied in each bioreactor system for treating polluted water with nitrate and organics. Results demonstrated that addition of A.H.corncob could achieve simultaneous removal of nitrogen and organics, and coupling of SPR-1 suspension filler with A.H.corncob (R 2 ) had the best performance. In coupling system of R 2 , the total nitrogen (TN) removal rate improved from below 10% to 55.92 ± 18.27% with effluent COD Mn concentration maintaining at a low level of 2.67 ± 0.44 mg L -1 . Microbial analysis of combined filler system demonstrated that conventional plastic filler mainly accumulated non-solid-phase denitrifiers for both nitrate and organics removal including genera Salipiger, Enterobacteriaceae etc. while A.H.corncob carrier was stronghold of solid-phase denitrifiers (Runella, etc.) directly using lignocellulosic materials as carbon source and fermentative bacteria (Coprococcus, etc.) for supplementing available carbon sources for denitrifiers in the system, which were integrated to achieve simultaneous removal of nitrate and organics.

Measurement of composite resin filler particles by using scanning electron microscopy and digital imaging.

PubMed

Jaarda, M J; Lang, B R; Wang, R F; Edwards, C A

1993-04-01

Composite resins are routinely classified on the basis of filler particle size for purposes of research, clinical applications, and communications. The size and characterizations of filler particles have also been considered a significant factor in the rate of wear of composites. Making valid correlations between the filler particles within a composite and wear requires accuracy of filler particle size and characterization. This study was initiated to examine two methods that would (1) qualify the filler particle content of a composite resin and (2) quantify the number, size, and the area occupied by the filler particles in composite resins. Three composite resins, BIS-FIL I, Visio-Fil, and Ful-Fil, were selected as the materials to be examined, on the basis of their published composite classification type as fine particle. The findings demonstrated that scientific methods are available to examine qualitatively and measure quantitatively the composite resin filler particles in terms of their numbers, sizes, and area occupied by use of a scanning electron microscope and digital imaging. Significant differences in the filler particle numbers, sizes, and the area occupied were found for the three composite resins in this study that were classified as fine particle.

Influence of filler loading on the two-body wear of a dental composite.

PubMed

Hu, X; Marquis, P M; Shortall, A C

2003-07-01

The purpose of the study was to explore the fundamental wear behaviour of a dental composite with different filler loadings under two-body wear conditions. The parent resin and filler components were mixed according to different weight ratios to produce experimental composites with filler loadings ranging from 20 to 87.5% by weight. A two-body wear test was conducted on the experimental composites using a wear-testing machine. The machine was designed to simulate the impact of the direct cyclic masticatory loading that occurs in the occlusal contact area in vivo. The results showed that there was little increase in the rate of wear with filler loadings below 60 wt%, but a sharp increase between 80 and 87.5 wt% in filler loading. Wide striations and bulk loss of material were apparent on the wear surfaces at higher filler loadings. Coefficients of friction increased with filler loading and followed the increase in rate of wear loss closely. It was concluded that, under two-body wear conditions, addition of high levels of filler particles into the resin matrix could reduce the wear resistance of dental composites. This finding may help when designing future dental composites for use in particular clinical settings.

Thermal, Morphological and Rheological Properties of Rigid Polyurethane Foams as Thermal Insulating Materials

NASA Astrophysics Data System (ADS)

Kim, Ji Mun; Han, Mi Sun; Kim, Youn Hee; Kim, Woo Nyon

2008-07-01

The polyurethane foams (PUFs) were prepared by polyether polyols, polymeric 4,4'-diphenylmethane diisocyanate (PMDI), silicone surfactants, amine catalysts and cyclopentane as a blowing agent. Solid and liquid type fillers were used as a nucleating agent to decrease a cell size of the PUFs as well as improve the thermal insulating properties of the PUFs. The PUFs were prepared by adding solid and liquid type fillers in the range of 1 to 3 wt%. For the liquid type fillers, the cell size of the PUFs showed minimum and found to decrease compared the PUF without adding fillers. Also, thermal conductivity of the PUFs with adding fillers showed minimum. For the solid type fillers, cell size and thermal conductivity of the PUFs were observed to decrease with the filler content up to 3 wt%. From these results, it is suggested that the thermal insulating property of the PUFs can be improved by adding fillers as a nucleating agent. Also, storage and loss modulus of the PUFs will be presented to study gelling points of the PUFs.

Study of Tetrapodal ZnO-PDMS Composites: A Comparison of Fillers Shapes in Stiffness and Hydrophobicity Improvements

PubMed Central

Jin, Xin; Deng, Mao; Kaps, Sören; Zhu, Xinwei; Hölken, Iris; Mess, Kristin; Adelung, Rainer; Mishra, Yogendra Kumar

2014-01-01

ZnO particles of different size and structures were used as fillers to modify the silicone rubber, in order to reveal the effect of the filler shape in the polymer composites. Tetrapodal shaped microparticles, short microfibers/whiskers, and nanosized spherical particles from ZnO have been used as fillers to fabricate the different ZnO-Silicone composites. The detailed microstructures of the fillers as well as synthesized composites using scanning electron microscopy have been presented here. The tensile elastic modulus and water contact angle, which are important parameters for bio-mimetic applications, of fabricated composites with different fillers have been measured and compared. Among all three types of fillers, tetrapodal shaped ZnO microparticles showed the best performance in terms of increase in hydrophobicity of material cross-section as well as the stiffness of the composites. It has been demonstrated that the tetrapodal shaped microparticles gain their advantage due to the special shape, which avoids agglomeration problems as in the case for nanoparticles, and the difficulty of achieving truly random distribution for whisker fillers. PMID:25208080

Study of tetrapodal ZnO-PDMS composites: a comparison of fillers shapes in stiffness and hydrophobicity improvements.

PubMed

Jin, Xin; Deng, Mao; Kaps, Sören; Zhu, Xinwei; Hölken, Iris; Mess, Kristin; Adelung, Rainer; Mishra, Yogendra Kumar

2014-01-01

ZnO particles of different size and structures were used as fillers to modify the silicone rubber, in order to reveal the effect of the filler shape in the polymer composites. Tetrapodal shaped microparticles, short microfibers/whiskers, and nanosized spherical particles from ZnO have been used as fillers to fabricate the different ZnO-Silicone composites. The detailed microstructures of the fillers as well as synthesized composites using scanning electron microscopy have been presented here. The tensile elastic modulus and water contact angle, which are important parameters for bio-mimetic applications, of fabricated composites with different fillers have been measured and compared. Among all three types of fillers, tetrapodal shaped ZnO microparticles showed the best performance in terms of increase in hydrophobicity of material cross-section as well as the stiffness of the composites. It has been demonstrated that the tetrapodal shaped microparticles gain their advantage due to the special shape, which avoids agglomeration problems as in the case for nanoparticles, and the difficulty of achieving truly random distribution for whisker fillers.

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

Selamat, Mohd Zulkefli, E-mail: azulkeflis@utem.edu.my; Yusuf, Muhammad Yusri Md, E-mail: yusri.cheras@gmail.com; Wer, Tio Kok, E-mail: to91@hotmail.my

Bipolar plates are key components in Proton Exchange Membrane (PEM) fuel cells. They carry current away from the cell and withstand the clamping force of the stack assembly. Therefore, PEM fuel cell bipolar plates must have high electrical conductivity and adequate mechanical strength, in addition to being light weight and low cost in terms of both applicable materials and production methods. In this research, the raw materials used to fabricate the high performance bipolar plate are Graphite (Gr), Stannum (Sn) and Polypropylene (PP). All materials used was in powder form and Gr and Sn act as fillers and the PPmore » acts as binder. The ratio of fillers (Gr/Sn) and binder (PP) was fixed at 80:20. For the multi-conductive filler, small amount of Sn, which is 10 up to 20wt% (from the total weight of fillers 80%) have been added into Gr/Sn/PP composite. The fillers were mixed by using the ball mill machine. The second stage of mixing process between the mixer of fillers and binder is also carried out by using ball mill machine before the compaction process by the hot press machine. The effect of formation temperatures (160°C-170°C) on the properties of Gr/Sn/PP composite had been studied in detail, especially the electrical conductivity, bulk density, hardness and microstructure analysis of Gr/Sn/PP composite. The result shows that there are significant improvement in the electrical conductivity and bulk density, which are exceeding the US-DoE target with the maximum value of 265.35 S/cm and 1.682g/cm{sup 3} respectively.« less

Physicochemical Characterization of Functional Lignin–Silica Hybrid Fillers for Potential Application in Abrasive Tools

PubMed Central

Strzemiecka, Beata; Klapiszewski, Łukasz; Jamrozik, Artur; Szalaty, Tadeusz J.; Matykiewicz, Danuta; Sterzyński, Tomasz; Voelkel, Adam; Jesionowski, Teofil

2016-01-01

Functional lignin–SiO2 hybrid fillers were prepared for potential application in binders for phenolic resins, and their chemical structure was characterized. The properties of these fillers and of composites obtained from them with phenolic resin were compared with those of systems with lignin or silica alone. The chemical structure of the materials was investigated by Fourier transform infrared spectroscopy (FT-IR) and carbon-13 nuclear magnetic resonance spectroscopy (13C CP MAS NMR). The thermal stability of the new functional fillers was examined by thermogravimetric analysis–mass spectrometry (TG-MS). Thermo-mechanical properties of the lignin–silica hybrids and resin systems were investigated by dynamic mechanical thermal analysis (DMTA). The DMTA results showed that abrasive composites with lignin–SiO2 fillers have better thermo-mechanical properties than systems with silica alone. Thus, fillers based on lignin might provide new, promising properties for the abrasive industry, combining the good properties of lignin as a plasticizer and of silica as a filler improving mechanical properties. PMID:28773639

Ceramic/metal and A15/metal superconducting composite materials exploiting the superconducting proximity effect and method of making the same

DOEpatents

Holcomb, Matthew J.

1999-01-01

A composite superconducting material made of coated particles of ceramic superconducting material and a metal matrix material. The metal matrix material fills the regions between the coated particles. The coating material is a material that is chemically nonreactive with the ceramic. Preferably, it is silver. The coating serves to chemically insulate the ceramic from the metal matrix material. The metal matrix material is a metal that is susceptible to the superconducting proximity effect. Preferably, it is a NbTi alloy. The metal matrix material is induced to become superconducting by the superconducting proximity effect when the temperature of the material goes below the critical temperature of the ceramic. The material has the improved mechanical properties of the metal matrix material. Preferably, the material consists of approximately 10% NbTi, 90% coated ceramic particles (by volume). Certain aspects of the material and method will depend upon the particular ceramic superconductor employed. An alternative embodiment of the invention utilizes A15 compound superconducting particles in a metal matrix material which is preferably a NbTi alloy.

Aerospace Ceramic Materials: Thermal, Environmental Barrier Coatings and SiC/SiC Ceramic Matrix Composites for Turbine Engine Applications

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2018-01-01

Ceramic materials play increasingly important roles in aerospace applications because ceramics have unique properties, including high temperature capability, high stiffness and strengths, excellent oxidation and corrosion resistance. Ceramic materials also generally have lower densities as compared to metallic materials, making them excellent candidates for light-weight hot-section components of aircraft turbine engines, rocket exhaust nozzles, and thermal protection systems for space vehicles when they are being used for high-temperature and ultra-high temperature ceramics applications. Ceramic matrix composites (CMCs), including non-oxide and oxide CMCs, are also recently being incorporated in gas turbine engines for high pressure and high temperature section components and exhaust nozzles. However, the complexity and variability of aerospace ceramic processing methods, compositions and microstructures, the relatively low fracture toughness of the ceramic materials, still remain the challenging factors for ceramic component design, validation, life prediction, and thus broader applications. This ceramic material section paper presents an overview of aerospace ceramic materials and their characteristics. A particular emphasis has been placed on high technology level (TRL) enabling ceramic systems, that is, turbine engine thermal and environmental barrier coating systems and non-oxide type SiC/SiC CMCs. The current status and future trend of thermal and environmental barrier coatings and SiC/SiC CMC development and applications are described.

Exceptionally strong, stiff and hard hybrid material based on an elastomer and isotropically shaped ceramic nanoparticles.

PubMed

Georgopanos, Prokopios; Schneider, Gerold A; Dreyer, Axel; Handge, Ulrich A; Filiz, Volkan; Feld, Artur; Yilmaz, Ezgi D; Krekeler, Tobias; Ritter, Martin; Weller, Horst; Abetz, Volker

2017-08-04

In this work the fabrication of hard, stiff and strong nanocomposites based on polybutadiene and iron oxide nanoparticles is presented. The nanocomposites are fabricated via a general concept for mechanically superior nanocomposites not based on the brick and mortar structure, thus on globular nanoparticles with nanosized organic shells. For the fabrication of the composites oleic acid functionalized iron oxide nanoparticles are decorated via ligand exchange with an α,ω-polybutadiene dicarboxylic acid. The functionalized particles were processed at 145 °C. Since polybutadiene contains double bonds the nanocomposites obtained a crosslinked structure which was enhanced by the presence of oxygen or sulfur. It was found that the crosslinking and filler percolation yields high elastic moduli of approximately 12-20 GPa and hardness of 15-18 GPa, although the polymer volume fraction is up to 40%. We attribute our results to a catalytically enhanced crosslinking reaction of the polymer chains induced by oxygen or sulfur and to the microstructure of the nanocomposite.

Advanced Ceramic Armor Materials

DTIC Science & Technology

1990-05-11

materials, toughened alumina, fiber -reinforced glass matrix composites, and multilayer-gradient materials for ballistic testing. Fabrication and...material systems: Multilayer advanced armor materials consisting of a hard ceramic faceplate bonded to a graphite fiber -reinforced glass matrix...toughened alumina, and fiber - applied studies of advanced reinforced ceramic matrix glass and glass -ceramic composites for ballistic testing. technologies

The Role of Nanofillers in Polymer Nanocomposites

NASA Astrophysics Data System (ADS)

Xu, Di

Polymer nanocomposites have been widely used in many fields. By introducing nanoparticles as fillers, researchers are able to get reinforced materials and new materials with novel properties, such as stronger mechanics, enhanced optical properties and improved conductivity. Though experimental techniques have rapidly advanced to enable better control of materials at atomic level, there is still a lack of a fundamental understanding of the dynamics and structure-properties relations in polymer nanocomposites. In this thesis, we use computer simulations to study the molecular structure and connections between microstate to macro properties of a variety of nanocomposites. Our goal is to understand the role of nanofillers in complex nanocomposite systems and to assist nanocomposite design. Nanoplatelet fillers, such as clays, have shown superior effects on the properties of polymer gels. We used molecular dynamic simulation to study nanoplatelet-filled composite gel system, in which short-range attraction exists between the polymer and nanoplatelet fillers. We show that the polymers and nanoplatelet fillers formed organic-inorganic networks with nanoplatelets acting as crosslink junctions, and the network eventually percolates the system as fillers reached a critical concentration. Stress auto-correlation and step-strain test were applied to investigate the mechanical properties; the results show the simulated composites changed from fluid-like to solid-like. The mechanical changes were consistent with the percolation transition, and gelation mechanism was therefore believed to be similar to those pure polymer physical gels. It was observed platelets aggregated into a local intercalation structure, which significantly differs from typical spherical fillers. This unique intercalation structure was examined by radial distribution function and ordering parameters. We discussed how intercalation would affect the properties of the platelet composites by comparing them with spherical fillers. Nanofillers have been widely used in polymer blends to improve the interfacial compatibility of otherwise immiscible polymers. In the second system, we investigated the interfacial behavior of binary polymer blends with different types of fillers. The interfacial tension and shear resistance were studied as a function of filler-polymer interaction, filler concentration and species of fillers. We found filler-polymer interaction is the key factor to improve the interfacial compatibility. The results show that nanofillers reduce both interfacial tension and interfacial slip at strong filler-polymer interaction. The effects of nanofillers however differ significantly from each other by their shapes. We analyzed the structure of nanofillers at the interface and their effects on the interfacial behaviors. The self-assembly of polymers into a columnar structure, while subject to a thin film environment, provides an economic route to fabricate polymer solar cell (PSC) with high conversion efficiency. In our work, we showed that two immiscible polymer segregates into to a percolating columnar structure when confined to a thin film. By adding nanofillers, with specific functionality, we can template the segregation of nanofillers to the polymer-polymer interface. We prove this process is surface tension driven and is a result that is particular for thin film geometries, where the thickness is under critical value. The results provide a theoretical basis for the column structure forming in a self-assembled PSC system, and can help to select polymer candidates that optimize PSC efficiency. These studies serve as theoretical guideline for engineering novel nanocomposites, and could lead to the design of materials with new and improved properties.

Influence of processing conditions on the morphology of expanded perlite/polypropylene composites

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

Mattausch, H., E-mail: hannelore.mattausch@unileoben.ac.at, E-mail: stephan.laske@unileoben.ac.at; Laske, S., E-mail: hannelore.mattausch@unileoben.ac.at, E-mail: stephan.laske@unileoben.ac.at; Holzer, C., E-mail: clemens.holzer@unileoben.ac.at

Perlite is an oversaturated, volcanic, glassy rock, which has chemically bound water from 2 to 5 wt%. Upon heating, perlite can be expanded up to 20 times of its original volume. Important applications are in the field of building industry, in refrigeration engineering or the pharmaceutical industry. As mineral filler in polymers, expanded perlite can increase the thermal conductivity, the viscosity and the mechanical properties of polypropylene composites. But there are still many challenges that must be analyzed to reach the full potential of those composites. This research work focuses on the morphology of expanded perlite/polypropylene (PP) compounds and themore » interactions between filler and polymer. To achieve good performance a homogenous dispersion of the filler in the polymer matrix is needed because the enhancement of the material correlates strongly with the morphology of the composite. Therefore it is necessary to characterize the microstructure of these materials in order to establish adequate structure-process-property relationships. The expanded perlite/PP composites were compounded with a co-rotating twin screw extruder Theysohn TSK 30/40D. For producing the closed cell expanded perlite a new technology, the bublon process, was used. For the material characterization two particles sizes were chosen and the filler content was varied at 5, 10 and 15 wt%. For the analysis of the effects of the screw geometry, two setups have been chosen for the processing of the materials. The produced materials were analyzed by scanning electron microscope (SEM) and tensile testing. The results show a reinforcement effect of the filler and differences in the inner structure of expanded perlite and in the morphology.« less

Improved TIG weld joint strength in aluminum alloy 2219-T87 by filler metal substitution

NASA Technical Reports Server (NTRS)

Poorman, R. M.; Lovoy, C. V.

1972-01-01

The results of an investigation on weld joint characteristics of aluminum alloy 2219-T87 are given. Five different alloys were utilized as filler material. The mechanical properties of the joints were determined at ambient and cryogenic temperatures for weldments in the as-welded condition and also, for weldments after elevated temperature exposures. Other evaluations included hardness surveys, stress corrosion susceptibility, and to a limited extent, the internal metallurgical weld structures. The overall results indicate that M-943 filler weldments are superior in strength to weldments containing either the standard 2319 filler or fillers 2014, 2020, and a dual wire feed consisting of three parts 2319 and one part 5652. In addition, no deficiencies were evident in M-934 filler weldments with regard to ductility, joint strength after elevated temperature exposure, weld hardness, metallographic structures, or stress corrosion susceptibility.

Hybrid Composite Material and Solid Particle Erosion Studies

NASA Astrophysics Data System (ADS)

Chellaganesh, D.; Khan, M. Adam; Ashif, A. Mohamed; Ragul Selvan, T.; Nachiappan, S.; Winowlin Jappes, J. T.

2018-04-01

Composite is one of the predominant material for most challenging engineering components. Most of the components are in the place of automobile structure, aircraft structures, and wind turbine blade and so on. At the same all the components are indulged to mechanical loading. Recent research on composite material are machinability, wear, tear and corrosion studies. One of the major issue on recent research was solid particle air jet erosion. In this paper hybrid composite material with and without filler. The fibre are in the combination of hemp – kevlar (60:40 wt.%) as reinforcement using epoxy as a matrix. The natural material palm and coconut shell are used as filler materials in the form of crushed powder. The process parameter involved are air jet velocity, volume of erodent and angle of impingement. Experiment performed are in eight different combinations followed from 2k (k = 3) factorial design. From the investigation surface morphology was studied using electron microscope. Mass change with respect to time are used to calculate wear rate and the influence of the process parameters. While solid particle erosion the hard particle impregnates in soft matrix material. Influence of filler material has reduced the wear and compared to plain natural composite material.

Jacketed lamp bulb envelope

DOEpatents

MacLennan, Donald A.; Turner, Brian P.; Gitsevich, Aleksandr; Bass, Gary K.; Dolan, James T.; Kipling, Kent; Kirkpatrick, Douglas A.; Leng, Yongzhang; Levin, Izrail; Roy, Robert J.; Shanks, Bruce; Smith, Malcolm; Trimble, William C.; Tsai, Peter

2001-01-01

A jacketed lamp bulb envelope includes a ceramic cup having an open end and a partially closed end, the partially closed end defining an aperture, a lamp bulb positioned inside the ceramic cup abutting the aperture, and a reflective ceramic material at least partially covering a portion of the bulb not abutting the aperture. The reflective ceramic material may substantially fill an interior volume of the ceramic cup not occupied by the bulb. The ceramic cup may include a structural feature for aiding in alignment of the jacketed lamp bulb envelope in a lamp. The ceramic cup may include an external flange about a periphery thereof. One example of a jacketed lamp bulb envelope includes a ceramic cup having an open end and a closed end, a ceramic washer covering the open end of the ceramic cup, the washer defining an aperture therethrough, a lamp bulb positioned inside the ceramic cup abutting the aperture, and a reflective ceramic material filling an interior volume of the ceramic cup not occupied by the bulb. A method of packing a jacketed lamp bulb envelope of the type comprising a ceramic cup with a lamp bulb disposed therein includes the steps of filling the ceramic cup with a flowable slurry of reflective material, and applying centrifugal force to the cup to pack the reflective material therein.

Process for recovering filler from polymer

DOEpatents

Smith, Maurice L.; Smith, Robert M.

1978-01-01

This disclosure relates to a process for recovering filler material from a polymeric matrix by reacting the matrix at an elevated temperature in a gas atmosphere with a controlled oxidizing potential and thereafter separating and cleaning the residue from the reaction mixture.

AC Electric Field Activated Shape Memory Polymer Composite

NASA Technical Reports Server (NTRS)

Kang, Jin Ho; Siochi, Emilie J.; Penner, Ronald K.; Turner, Travis L.

2011-01-01

Shape memory materials have drawn interest for applications like intelligent medical devices, deployable space structures and morphing structures. Compared to other shape memory materials like shape memory alloys (SMAs) or shape memory ceramics (SMCs), shape memory polymers (SMPs) have high elastic deformation that is amenable to tailored of mechanical properties, have lower density, and are easily processed. However, SMPs have low recovery stress and long response times. A new shape memory thermosetting polymer nanocomposite (LaRC-SMPC) was synthesized with conductive fillers to enhance its thermo-mechanical characteristics. A new composition of shape memory thermosetting polymer nanocomposite (LaRC-SMPC) was synthesized with conductive functionalized graphene sheets (FGS) to enhance its thermo-mechanical characteristics. The elastic modulus of LaRC-SMPC is approximately 2.7 GPa at room temperature and 4.3 MPa above its glass transition temperature. Conductive FGSs-doped LaRC-SMPC exhibited higher conductivity compared to pristine LaRC SMP. Applying an electric field at between 0.1 Hz and 1 kHz induced faster heating to activate the LaRC-SMPC s shape memory effect relative to applying DC electric field or AC electric field at frequencies exceeding1 kHz.

Effect of Carbon on the Electrical Properties of Copper Oxide-Based Bulk Composites

NASA Astrophysics Data System (ADS)

Kalinin, Yu. E.; Kashirin, M. A.; Makagonov, V. A.; Pankov, S. Yu.; Sitnikov, A. V.

2018-04-01

The effect of carbon filler on the electrical resistance and the thermopower of copper oxide-based composites produced by ceramic technology by hot pressing has been studied. It is found that the dependences of the electrical resistivity on the filler concentration are characteristic by S-like curves that are typical of percolation systems; in this case, the resistivity decreases more substantially as the carbon content increases as compared to the decrease in thermopower value, which is accompanied by the existence of the maximum of the factor of thermoelectric power near the percolation threshold. The studies of the temperature dependences of the resistivity and the thermopower at low temperatures show that, in the range 240-300 K, the predominant mechanism of the electrotransfer of all the composites under study is the hopping mechanism. At temperatures lower than 240 K, the composites with a nanocrystalline CuO matrix have a hopping conductivity with a variable hopping distance over localized states of the matrix near the Fermi level, which is related to the conductivity over intergrain CuO boundaries. A schematic model of the band structure of nanocrystalline CuO with carbon filler is proposed on the base of the analysis of the found experimental regularities of the electrotransfer.

Dielectric properties of PVDF/0.5(Ba0.7Ca0.3)TiO3-0.5Ba(Zr0.2Ti0.8)O3 composites

NASA Astrophysics Data System (ADS)

Pandey, Bablu K.; Chandra, K. P.; Kolte, Jayant; Kulkarni, A. R.; Jayaswal, S. K.; Prasad, K.

2018-05-01

Ceramic powder of 0.50(Ba0.7Ca0.3)TiO3-0.50Ba(Zr0.2Ti0.8)O3(BCZT50) at morphotropic phase boundary composition was prepared usingsolid-statesynthesis technique followed by extensive high energy ball milling. The crystal symmetry, space group and unit cell dimensions were determined from the X-raydiffraction data of BCZT50 using FullProf software andthe average crystallite size was estimated using Williamson-Hall approach. FTIR spectra confirmed the formation of perovskite type solid solutions. The prepared ceramic powder was utilized to prepare lead-free (1- x)PVDF/xBCZT50 ceramic-polymer composites with x = 0.025, 0.05, 0.10, 0.15, 0.20, 0.25 were prepared using melt- mixing technique. The distribution of BCZT50 particles in the PVDF matrix were examined using anoptical microscope. Filler concentration dependent real and imaginary parts of dielectric constant data followed exponential growth types of variation. The low value of tanδ(˜10-2) can be advantageous forsensing/detectionapplications.

A concept for improved fire-safety through coated fillers

NASA Technical Reports Server (NTRS)

Ramohalli, K.

1977-01-01

A possible method is examined for obtaining a high value of thermal conductivity before ignition and a low value after ignition in standard composite materials. The idea is to coat fiberglass, alumina trihydrate, and similar fillers with specially selected chemicals prior to using polymer resins. The amount of the coat constitutes typically less than 5% of the material's total weight. The experimental results obtained are consistent with the basic concept.

Low-Thermal-Expansion Filled Polytetrafluoroethylene

NASA Technical Reports Server (NTRS)

Shapiro, Sanford S.

1989-01-01

PTFE made thermally compatible with aluminum without changing dielectric constant. Manufactured with fillers and pores to reduce coefficient of thermal expansion by factor of 6 to match aluminum. Material retains 2.1 dielectric constant of pure PTFE. Combines filler and micropore concepts. Particles and voids embedded in PTFE matrix function cooperatively. Particles take up compressive stress imposed by contracting PTFE, and voids take up expanding material. Increases dielectric constant, while voids reduce it.

High-Energy-Density LCA-Coupled Structural Energetic Materials for Counter WMD Applications

DTIC Science & Technology

2014-04-01

reactive ( thermite ) fillers as high-energy-density structural energetic materials. The specific objectives include performing fundamental studies to...a) investigate mechanics of dynamic densification and reaction initiation in Ta+Fe2O3 and Ta+Bi2O3 thermite powder mixtures and to (b) design and...initiation in the thermite filler and allow controlled fragmentation. Linear Cellular A; counter WMDs; shock-compression and impact-initiated reactions

Evaluation of surface roughness and polishing techniques for new ceramic materials.

PubMed

Campbell, S D

1989-05-01

The surface roughness of crown and bridge materials should be minimized to obtain optimal biocompatability. This study used scanning electron microscopy to evaluate the effect of polishing procedures on two all-ceramic crown materials (Dicor and Cerestore). The "as formed," unpolished specimens of both Dicor and Cerestore materials presented a rough surface. It was found that any attempt to polish the Cerestore coping material resulted in an extremely rough surface. Finishing of the Dicor ceramic resulted in a smoother but pitted surface. Polishing of both ceramic materials resulted in a surface that was rougher than the glazed metal ceramic controls. The smoothest finish was obtained when the glazed veneer (Cerestore) and shading porcelain (Dicor) were applied to the all-ceramic materials.

Filler characteristics of modern dental resin composites and their influence on physico-mechanical properties.

PubMed

Randolph, Luc D; Palin, William M; Leloup, Gaëtane; Leprince, Julian G

2016-12-01

The mechanical properties of dental resin-based composites (RBCs) are highly dependent on filler characteristics (size, content, geometry, composition). Most current commercial materials are marketed as "nanohybrids" (i.e. filler size <1μm). In the present study, filler characteristics of a selection of RBCs were described, aiming at identifying correlations with physico-mechanical properties and testing the relevance of the current classification. Micron/sub-micron particles (> or <500nm) were isolated from 17 commercial RBCs and analyzed by laser diffractrometry and/or electron microscopy. Filler and silane content were evaluated by thermogravimetric analysis and a sedimentation technique. The flexural modulus (E flex ) and strength (σ flex ) and micro-hardness were determined by three-point bending or with a Vickers indenter, respectively. Sorption was also determined. All experiments were carried out after one week of incubation in water or 75/25 ethanol/water. Average size for micron-sized fillers was almost always higher than 1μm. Ranges for mechanical properties were: 3.775wt%) were associated with the highest mechanical properties (E flex and σ flex >12GPa and 130MPa, respectively) and lowest solvent sorption (∼0.3%). Mechanical properties and filler characteristics significantly vary among modern RBCs and the current classification does not accurately illustrate either. Further, the chemical stability of RBCs differed, highlighting differences in resin and silane composition. Since E flex and sorption were well correlated to the filler content, a simple and unambiguous classification based on such characteristic is suggested, with three levels (ultra-low fill, low-fill and compact resin composites). Copyright © 2016 The Academy of Dental Materials. All rights reserved.

Synthesis and characterization of polymer matrix composite material with combination of ZnO filler and nata de coco fiber as a candidate of semiconductor material

NASA Astrophysics Data System (ADS)

Saputra, Asep Handaya; Anindita, Hana Nabila

2015-12-01

Synthesis of semiconductor composite using acrylic matrix filled with ZnO and nata de coco fiber has been conducted in this research. The purpose of this research is to obtain semiconductor composite material that has a good mechanical strength and thermal resistance. In situ polymerization method is used in this research and the composites are ready to be characterized after 12 hours. The main parameter that is characterized is the electric conductivity of the composite. Additional parameters are also characterized such as composite's elastic modulus and glass transition temperature. The composites that has been made in this research can be classified as semiconductor material because the conductivity is in the range of 10-8-103 S/cm. In general the addition of ZnO and nata de coco filler can increase the conductivity of the composite. The highest semiconductor characteristic in acrylic/ZnO composite is obtained from 30% volume filler that reach 3.4 x 10-7 S/cm. Similar with acrylic/ZnO composite, in acrylic/nata de coco fiber composite the highest semiconductor characteristic is also obtained from 30% volume filler that reach 1.15 x 10-7 S/cm. Combination of 20% volume of ZnO, 10% volume of nata de coco, and 70% volume of acrylic resulting in composite with electric conductivity of 1.92 x 10-7 S/cm. In addition, combination of ZnO and nata de coco fiber as filler in composite can also improve the characteristic of composite where composite with 20% volume of ZnO filler and 10% volume of nata de coco fiber resulting in composite with elastic modulus of 1.79 GPa and glass transition temperature of 175.73°C which is higher than those in acrylic/ZnO composite.

The use of Ni-Cr-Si-Be filler metals for brazing of stainless steels

NASA Astrophysics Data System (ADS)

Ivannikov, A.; Fedotov, V.; Suchkov, A.; Penyaz, M.; Fedotov, I.; Tarasov, B.

2016-04-01

Nanocrystalline ribbon filler metal-alloys of system Ni-Cr-Si-Be are produced by the rapidly quenching of the melt method. By these filler metals carried out hight temperature vacuum brazing of austenitic steels (12Kh18N10T and Kh18N8G2) and austenitic-ferritic class EI-811 (12Kh21N5T). The basic laws of structure-phase state foundation of brazed joints are determined, features of the interaction of the molten filler metal to the brazed materials are identified, the optimal temperature and time parameters of the brazing process are determined.

Organic filler from golden apple snails shells to improve the silicone rubber insulator properties

NASA Astrophysics Data System (ADS)

Tepsila, Sujirat; Suksri, Amnart

2018-02-01

This paper investigates the effect of an addition of filler compound using golden apple snail shell as an organic filler to the silicone rubber insulator. The filler obtained from golden apple snail shell is found mostly contained calcium carbonate. The organic calcium carbonate (CaCO3) with particle size of 45, 75, 100 and 300 micron were prepared. Sample of silicone rubber that were filled with fillers were tested under ASTM D638-02a type standard for mechanical test. Also, electrical test such as I-V characteristics (ASTM D257-07) and dry arc test according to ASTM D495-14 have been performed. The results revealed that using larger particle size of organic filler obtained from the golden apple snail shell resulted to higher value of dielectric constant as well as higher dielectric strength. Also, the filler helps slow down the tracking activity at an insulator surface due to its crystals of calcium carbonate. However, when using excessive amount of filler, the sample will have a drawbacks in mechanical properties. By using agriculture waste as a filler compound, one can reduced the usage of commercial CaCO3 as an inorganic materials and to lower the investment cost to a final silicone rubber product.

Are functional fillers improving environmental behavior of plastics? A review on LCA studies.

PubMed

Civancik-Uslu, Didem; Ferrer, Laura; Puig, Rita; Fullana-I-Palmer, Pere

2018-06-01

The use of functional fillers can be advantageous in terms of cost reduction and improved properties in plastics. There are many types of fillers used in industry, organic and inorganic, with a wide application area. As a response to the growing concerns about environmental damage that plastics cause, recently fillers have started to be considered as a way to reduce it by decreasing the need for petrochemical resources. Life cycle assessment (LCA) is identified as a proper tool to evaluate potential environmental impacts of products or systems. Therefore, in this study, the literature regarding LCA of plastics with functional fillers was reviewed in order to see if the use of fillers in plastics could be environmentally helpful. It was interesting to find out that environmental impacts of functional fillers in plastics had not been studied too often, especially in the case of inorganic fillers. Therefore, a gap in the literature was identified for the future works. Results of the study showed that, although there were not many and some differences exist among the LCA studies, the use of fillers in plastics industry may help to reduce environmental emissions. In addition, how LCA methodology was applied to these materials was also investigated. Copyright © 2018 Elsevier B.V. All rights reserved.

New Manufacturing Method for Paper Filler and Fiber Material

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

Doelle, Klaus

2013-08-25

The use of fillers in printing and writing papers has become a prerequisite for competing in a global market to reduce the cost of materials. Use of calcium carbonates (ranging from 18% to 30%) as filler is a common practice in the paper industry but the choices of fillers for each type of papers vary widely according to its use. The market for uncoated digital printing paper is one that continues to introduce exciting growth projections. and it is important to understand the effect that new manufacturing methods of calcium carbonates have on the energy efficiency and paper production. Research conducted under this award showed that the new fiber filler composite material has the potential to increase the paper filler content by up to 5% without losing mechanical properties. Benefits of the technology can be summarized as follows for a 1% filler increase per metric ton of paper produced: (i) production cost savings overmore » $$12, (ii) Energy savings of 100,900 btu, (iii) CO{sub 2} emission savings of 33 lbs, and additional savings for wood preparation, pulping, recovery of 203593 btu with a 46lbs of CO{sub 2} emission savings per 1% filler increase. In addition the technology has the potential to save: (i) additional $$3 per ton of bleached pulp produced, (ii) bleaching energy savings of 170,000 btu, (iii) bleaching CO{sub 2} emission savings of 39 lbs, and (iv) additional savings for replacing conventional bleaching chemicals with a sustainable bleaching chemical is estimated to be 900,000 btu with a 205 lbs of CO{sub 2} emission savings per ton of bleached pulp produced. All the above translates to a estimated annual savings for a 12% filler increase of 296 trillion buts or 51 million barrel of oil equivalent (BOE) or 13.7% of the industries energy demand. This can lead to a increase of renewable energy usage from 56% to close to 70% for the industry sector. CO{sub 2} emission of the industry at a 12% filler increase could be lowered by over 39 million tons annually. If the new technology could be implemented for bleaching process a total annual estimated energy savings potential of 64 trillion buts or 11 million barrel of oil equivalent (BOE) equal to 3% of the paper industries energy demand could be realized. This could lead to a increase of renewable energy usage from 56% to close to 60% for the industry. CO{sub 2} emissions could be lowered by over 7.4 million tons annually. It is estimated that an installed system could also yield a 75 to 100% return of investment (ROI) rate for the capital equipment that need to be installed for the fiber filler composite manufacturing process.« less

Effect of formation temperature on properties of graphite/stannum composite for bipolar plate

NASA Astrophysics Data System (ADS)

Selamat, Mohd Zulkefli; Yusuf, Muhammad Yusri Md; Wer, Tio Kok; Sahadan, Siti Norbaya; Malingam, Sivakumar Dhar; Mohamad, Noraiham

2016-03-01

Bipolar plates are key components in Proton Exchange Membrane (PEM) fuel cells. They carry current away from the cell and withstand the clamping force of the stack assembly. Therefore, PEM fuel cell bipolar plates must have high electrical conductivity and adequate mechanical strength, in addition to being light weight and low cost in terms of both applicable materials and production methods. In this research, the raw materials used to fabricate the high performance bipolar plate are Graphite (Gr), Stannum (Sn) and Polypropylene (PP). All materials used was in powder form and Gr and Sn act as fillers and the PP acts as binder. The ratio of fillers (Gr/Sn) and binder (PP) was fixed at 80:20. For the multi-conductive filler, small amount of Sn, which is 10 up to 20wt% (from the total weight of fillers 80%) have been added into Gr/Sn/PP composite. The fillers were mixed by using the ball mill machine. The second stage of mixing process between the mixer of fillers and binder is also carried out by using ball mill machine before the compaction process by the hot press machine. The effect of formation temperatures (160°C-170°C) on the properties of Gr/Sn/PP composite had been studied in detail, especially the electrical conductivity, bulk density, hardness and microstructure analysis of Gr/Sn/PP composite. The result shows that there are significant improvement in the electrical conductivity and bulk density, which are exceeding the US-DoE target with the maximum value of 265.35 S/cm and 1.682g/cm3 respectively.

Thermal Analysis of Filler Reinforced Polymeric Composites

NASA Astrophysics Data System (ADS)

Ghadge, Mahesh Devidas

Improving heat dissipating property of composite materials is becoming increasingly important in domains ranging from the automotive industry, electronic devices to aeronautical industry. Effective heat dissipation is required especially in aircraft and racing tires to guarantee high performance and good service life [1]. The present study is focused on improving the thermal conductivity of Emulsion-styrene butadiene rubber (ESBR) which is a cheap alternative to other rubber composites. The disadvantages of ESBR are low thermal conductivity and high heat generation. Adding fillers with high thermal conductivity to ESBR is proposed as a technique for improving the thermal conductivity of ESBR. The purpose of the research is to predict the thermal conductivity of ESBR when filled with fillers of much higher thermal conductivity and also to find out to what extent the filler properties affect the heat transfer capabilities of the composite matrix. The influence of different filler shapes i.e. spherical, cylindrical and platelets on the overall thermal capability of composite matrix is studied, the finite element modelings are conducted using Abaqus. Three-dimensional and two-dimensional models are created in Abaqus to simulate the microstructure of the composite matrix filled with fillers. Results indicate that the overall thermal conductivity increases with increasing filler loading i.e. for a filler volume fraction of 0.27, the conductivity increased by around 50%. Filler shapes, orientation angle, and aspect ratio of the fillers significantly influences the thermal conductivity. Conductivity increases with increasing aspect ratio (length/diameter) of the cylindrical fillers since longer conductive chains are able to form at the same volume percentage as compared to spherical fillers. The composite matrix reaches maximum thermal conductivity when the cylindrical fillers are oriented in the direction of heat flow. The heat conductivity predicted by FEM for ESBR is compared with that predicted by mean field theories. At low volume fractions the FEM and mean field theory results are matching. However, at high volume fractions, the results obtained by the two methods are not in agreement. This is due to the fact that mean field theory do not consider the particle interactions happening at higher volume fractions. The present analysis can be used to tailor the thermal properties of ESBR for required thermal conductivity for a wide range of applications such as racing tires, electronic gadgets or aeronautical components. In addition, the proposed FEM models can be used to design and optimize the properties of new composite materials providing more insight into the thermal conductivity of composite polymers and aid in understanding heat transfer mechanism of reinforced polymers.

Ceramic transactions - Materials processing and design: Grain-boundary-controlled properties of fine ceramics II. Volume 44

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

Niihara, Koichi; Ishizaki, Kozo; Isotani, Mitsuo

This volume contains selected papers presented at a workshop by the Japan Fine Ceramics Center, `Materials Processing and Design Through Better Control of Grain Boundaries: Emphasizing Fine Ceramics II,` which was held March 17-19, 1994, in Koda-cho, Aichi, Japan. The focus of the workshop was the application of grain boundary phenomena to materials processing and design. The topics covered included electronic materials, evaluation methods, structural materials, and interfaces. Also included is an illuminating overview of the current status of work on grain boundary assisted materials processing and design, particularly for fine ceramics. The volume`s chapter titles are: Electron Microscopy, Evaluation,more » Grain Boundary Control and Design, Functional Ceramics, Composite Materials, Synthesis and Sintering, and Mechanical Properties.« less

Ceramic electrolyte coating methods

DOEpatents

Seabaugh, Matthew M.; Swartz, Scott L.; Dawson, William J.; McCormick, Buddy E.

2004-10-12

Processes for preparing aqueous suspensions of a nanoscale ceramic electrolyte material such as yttrium-stabilized zirconia. The invention also includes a process for preparing an aqueous coating slurry of a nanoscale ceramic electrolyte material. The invention further includes a process for depositing an aqueous spray coating slurry including a ceramic electrolyte material on pre-sintered, partially sintered, and unsintered ceramic substrates and products made by this process.

Antibacterial activity of resin composites containing surface pre-reacted glass-ionomer (S-PRG) filler.

PubMed

Miki, Saeki; Kitagawa, Haruaki; Kitagawa, Ranna; Kiba, Wakako; Hayashi, Mikako; Imazato, Satoshi

2016-09-01

A surface pre-reacted glass-ionomer (S-PRG) filler is a technology of interest for providing bio-functions to restorative materials. Resin composites containing S-PRG filler have been reported to show less plaque accumulation and reduced bacterial attachment. In this study, experimental resin composites containing S-PRG filler at various concentrations were fabricated, and the inhibitory effects on bacterial growth on their surface and the association of ions released from S-PRG filler with antibacterial activity were evaluated. Five kinds of experimental resin composites containing S-PRG filler at 0, 13.9, 27.3, 41.8, or 55.9 (vol.%) were fabricated. Streptococcus mutans was cultured on the cured discs for 18h to examine the growth of bacteria in contact with the surface of the experimental resins. The concentrations of Al(3+), BO3(3-), F(-), Na(+), SiO3(2-), or Sr(2+) released from each experimental resin into water were measured. The standardized solutions of each ion were prepared at the concentrations determined to be released from the experimental resin, and their inhibitory effects of single ion species on S. mutans growth were evaluated by using each standardized solution. Resin composites containing S-PRG filler at 13.9 (vol.%) or greater inhibited S. mutans growth on their surface. When S. mutans was incubated in the presence of six kinds of ions at the concentrations released from the resin composite containing S-PRG filler at 55.9 (vol.%), a significant reduction in bacterial number was observed for BO3(3-), F(-), Al(3+), and SiO3(2-). Among these four ions, BO3(3-) and F(-) demonstrated the strongest inhibitory effect on S. mutans growth. Our findings suggest that resin composites containing S-PRG filler inhibit the growth of S. mutans on their surface. BO3(3-), F(-), Al(3+) and SiO3(2-) released from S-PRG filler have the ability to inhibit S. mutans growth, and the inhibitory effects are mainly attributed to release of BO3(3-) and F(-). Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Preparation and application of conducting polymer/Ag/clay composite nanoparticles formed by in situ UV-induced dispersion polymerization

PubMed Central

Zang, Limin; Qiu, Jianhui; Yang, Chao; Sakai, Eiichi

2016-01-01

In this work, composite nanoparticles containing polypyrrole, silver and attapulgite (PPy/Ag/ATP) were prepared via UV-induced dispersion polymerization of pyrrole using ATP clay as a templet and silver nitrate as photoinitiator. The effects of ATP concentration on morphology, structure and electrical conductivity were studied. The obtained composite nanoparticles with an interesting beads-on-a-string morphology can be obtained in a short time (10 min), which indicates the preparation method is facile and feasible. To explore the potential applications of the prepared PPy/Ag/ATP composite nanoparticles, they were served as multifunctional filler and blended with poly(butylene succinate) (PBS) matrix to prepare biodegradable composite material. The distribution of fillers in polymer matrix and the interfacial interaction between fillers and PBS were confirmed by scanning electron microscope, elemental mapping and dynamic mechanical analysis. The well dispersed fillers in PBS matrix impart outstanding antibacterial property to the biodegradable composite material as well as enhanced storage modulus due to Ag nanoparticles and ATP clay. The biodegradable composite material also possesses modest surface resistivity (106 ~ 109 Ω/◻). PMID:26839126

Evaluation of mechanical properties and durability performance of HDPE-wood composites

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

Tazi, M.; Erchiqui, F.; Kaddami, H.

The objective of this work is to evaluate the mechanical properties and durability performance of bio-composite materials made from sawdust and thermoplastic polymer (HDPE). For the preparation of the composites, sawdust in different proportions with Maleic Anhydride grafted Polyethylene (MAPE) as the coupling agent was used. The thermal and mechanical properties were successively characterized. The results indicate that adding wood fillers to a polymer matrix increases the degree of crystallinity and improves the tensile strength and ductility of composites. On the contrary, resistance to water absorption decreases as a function of the wood fillers. Scanning electron microscopy (SEM) was usedmore » to analyze morphological structure alteration when exposed to intense weathering. The biodegradability of bio-composites up to 97 days was also investigated; the results indicate that, by increasing the filler content, the amount of weight loss increased as well. In other words, even though the addition of sawdust to thermoplastic polymer improves the mechanical performance of a composite material, it also accelerates the biodegradation rate of the composite. An optimum amount of filler content might compromise the effect of biodegradation and mechanical properties of composite materials.« less

Preparation and application of conducting polymer/Ag/clay composite nanoparticles formed by in situ UV-induced dispersion polymerization.

PubMed

Zang, Limin; Qiu, Jianhui; Yang, Chao; Sakai, Eiichi

2016-02-03

In this work, composite nanoparticles containing polypyrrole, silver and attapulgite (PPy/Ag/ATP) were prepared via UV-induced dispersion polymerization of pyrrole using ATP clay as a templet and silver nitrate as photoinitiator. The effects of ATP concentration on morphology, structure and electrical conductivity were studied. The obtained composite nanoparticles with an interesting beads-on-a-string morphology can be obtained in a short time (10 min), which indicates the preparation method is facile and feasible. To explore the potential applications of the prepared PPy/Ag/ATP composite nanoparticles, they were served as multifunctional filler and blended with poly(butylene succinate) (PBS) matrix to prepare biodegradable composite material. The distribution of fillers in polymer matrix and the interfacial interaction between fillers and PBS were confirmed by scanning electron microscope, elemental mapping and dynamic mechanical analysis. The well dispersed fillers in PBS matrix impart outstanding antibacterial property to the biodegradable composite material as well as enhanced storage modulus due to Ag nanoparticles and ATP clay. The biodegradable composite material also possesses modest surface resistivity (10(6)~ 10(9) Ω/◻).

Clinical application of bio ceramics

NASA Astrophysics Data System (ADS)

Anu, Sharma; Gayatri, Sharma

2016-05-01

Ceramics are the inorganic crystalline material. These are used in various field such as biomedical, electrical, electronics, aerospace, automotive and optical etc. Bio ceramics are the one of the most active areas of research. Bio ceramics are the ceramics which are biocompatible. The unique properties of bio ceramics make them an attractive option for medical applications and offer some potential advantages over other materials. During the past three decades, a number of major advances have been made in the field of bio ceramics. This review focuses on the use of these materials in variety of clinical scenarios.

Clinical application of bio ceramics

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

Anu, Sharma, E-mail: issaranu@gmail.com; Gayatri, Sharma, E-mail: sharmagayatri@gmail.com

Ceramics are the inorganic crystalline material. These are used in various field such as biomedical, electrical, electronics, aerospace, automotive and optical etc. Bio ceramics are the one of the most active areas of research. Bio ceramics are the ceramics which are biocompatible. The unique properties of bio ceramics make them an attractive option for medical applications and offer some potential advantages over other materials. During the past three decades, a number of major advances have been made in the field of bio ceramics. This review focuses on the use of these materials in variety of clinical scenarios.

Plasma-modified graphene nanoplatelets and multiwalled carbon nanotubes as fillers for advanced rubber composites

NASA Astrophysics Data System (ADS)

Sicinski, M.; Gozdek, T.; Bielinski, D. M.; Szymanowski, H.; Kleczewska, J.; Piatkowska, A.

2015-07-01

In modern rubber industry, there still is a room for new fillers, which can improve the mechanical properties of the composites, or introduce a new function to the material. Modern fillers like carbon nanotubes or graphene nanoplatelets (GnP), are increasingly applied in advanced polymer composites technology. However, it might be hard to obtain a well dispersed system for such systems. The polymer matrix often exhibits higher surface free energy (SFE) level with the filler, which can cause problems with polymer-filler interphase adhesion. Filler particles are not wet properly by the polymer, and thus are easier to agglomerate. As a consequence, improvement in the mechanical properties is lower than expected. In this work, multi-walled carbon nanotubes (MWCNT) and GnP surface were modified with low-temperature plasma. Attempts were made to graft some functionalizing species on plasma-activated filler surface. The analysis of virgin and modified fillers’ SFE was carried out. MWCNT and GnP rubber composites were produced, and ultimately, their morphology and mechanical properties were studied.

[Research on the aging of all-ceramics restoration materials].

PubMed

Zhang, Dongjiao; Chen, Xinmin

2011-10-01

All-ceramic crowns and bridges have been widely used for dental restorations owing to their excellent functionality, aesthetics and biocompatibility. However, the premature clinical failure of all-ceramic crowns and bridges may easily occur when they are subjected to the complex environment of oral cavity. In the oral environment, all-ceramic materials are prone to aging. Aging can lead all-ceramic materials to change color, to lower bending strength, and to reduce anti-fracture toughness. There are many factors affecting the aging of the all-ceramic materials, for example, the grain size, the type of stabilizer, the residual stress and the water environment. In order to analyze the aging behavior, to optimize the design of all-ceramic crowns and bridges, and to evaluate the reliability and durability, we review in this paper recent research progress of aging behavior for all-ceramics restoration materials.

A review of mechanical and tribological behaviour of polymer composite materials

NASA Astrophysics Data System (ADS)

Prabhakar, K.; Debnath, S.; Ganesan, R.; Palanikumar, K.

2018-04-01

Composite materials are finding increased applications in many industrial applications. A nano-composite is a matrix to which nanosized particles have been incorporated to drastically improve the mechanical performance of the original material. The structural components produced using nano-composites will exhibit a high strength-to-weight ratio. The properties of nano-composites have caused researchers and industries to consider using this material in several fields. Polymer nanocomposites consists of a polymer material having nano-particles or nano-fillers dispersed in the polymer matrix which may be of different shapes with at least one of the dimensions less than 100nm. In this paper, comprehensive review of polymer nanocomposites was done majorly in three different areas. First, mechanical behaviour of polymer nanocomposites which focuses on the mechanical property evaluation such as tensile strength, impact strength and modulus of elasticity based on the different combination of filler materials and nanoparticle inclusion. Second, wear behavior of Polymer composite materials with respect to different impingement angles and variation of filler composition using different processing techniques. Third, tribological (Friction and Wear) behaviour of nanocomposites using various combination of nanoparticle inclusion and time. Finally, it summarized the challenges and prospects of polymer nanocomposites.

DC bias effect on alternating current electrical conductivity of poly(ethylene terephthalate)/alumina nanocomposites

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

Nikam, Pravin N., E-mail: pravinya26@gmail.com; Deshpande, Vineeta D., E-mail: drdeshpandevd@gmail.com

Polymer nanocomposites based on metal oxide (ceramic) nanoparticles are a new class of materials with unique properties and designed for various applications such as electronic device packaging, insulation, fabrication and automotive industries. Poly(ethylene terephthalate) (PET)/alumina (Al{sub 2}O{sub 3}) nanocomposites with filler content between 1 wt% and 5 wt% were prepared by melt compounding method using co-rotating twin screw extruder and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and precision LCR meter techniques. The results revealed that proper uniform dispersion at lower content up to 2 wt% of nano-alumina observed by using TEM. Aggregation of nanoparticles was observedmore » at higher content of alumina examined by using SEM and TEM. The frequency dependences of the alternating current (AC) conductivity (σ{sub AC}) of PET/alumina nanocomposites on the filler content and DC bias were investigated in the frequency range of 20Hz - 1MHz. The results showed that the AC and direct current (DC) conductivity increases with increasing DC bias and nano-alumina content upto 3 wt%. It follows the Jonscher’s universal power law of solids. It revealed that σ{sub AC} of PET/alumina nanocomposites can be well characterized by the DC conductivity (σ{sub DC}), critical frequency (ω{sub c}), critical exponent of the power law (s). Roll of DC bias potential led to an increase of DC conductivity (σ{sub DC}) due to the creation of additional conducting paths with the polymer nanocomposites and percolation behavior achieved through co-continuous morphology.« less

Effect of Processing Parameters on Thermal Cycling Behavior of Al2O3-Al2O3 Brazed Joints

NASA Astrophysics Data System (ADS)

Dandapat, Nandadulal; Ghosh, Sumana; Guha, Bichitra Kumar; Datta, Someswar; Balla, Vamsi Krishna

2016-10-01

In the present study, alumina ceramics were active metal brazed at different temperatures ranging from 1163 K to 1183 K (890 °C to 910 °C) using TICUSIL (68.8Ag-26.7Cu-4.5Ti in wt pct) foil as filler alloy of different thicknesses. The brazed joints were subjected to thermal cycling for 100 cycles between 323 K and 873 K (50 °C and 600 °C). The microstructural and elemental composition analysis of the brazed joints were performed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) before and after thermal cycling. Helium (He) leak test and brazing strength measurement were also conducted after thermal cycling for 100 cycles. The joint could withstand up to 1 × 10-9 Torr pressure and brazing strength was higher than 20 MPa. The experimental results demonstrated that joints brazed at the higher temperature with thinner filler alloy produced strong Al2O3-Al2O3 joints.

Updating Classifications of Ceramic Dental Materials: A Guide to Material Selection.

PubMed

McLaren, Edward A; Figueira, Johan

2015-06-01

The indications for and composition of today's dental ceramic materials serve as the basis for determining the appropriate class of ceramics to use for a given case. By understanding the classifications, composition, and characteristics of the latest all-ceramic materials, which are presented in this article in order of most to least conservative, dentists and laboratory technicians can best determine the ideal material for a particular treatment.

Hydridosiloxanes as precursors to ceramic products

DOEpatents

Blum, Yigal D.; Johnson, Sylvia M.; Gusman, Michael I.

1997-01-01

A method is provided for preparing ceramic precursors from hydridosiloxane starting materials and then pyrolyzing these precursors to give rise to silicious ceramic materials. Si--H bonds present in the hydridosiloxane starting materials are catalytically activated, and the activated hydrogen atoms may then be replaced with nonhydrogen substituents. These preceramic materials are pyrolyzed in a selected atmosphere to give the desired ceramic product. Ceramic products which may be prepared by this technique include silica, silicon oxynitride, silicon carbide, metal silicates, and mullite.

Hydridosiloxanes as precursors to ceramic products

DOEpatents

Blum, Y.D.; Johnson, S.M.; Gusman, M.I.

1997-06-03

A method is provided for preparing ceramic precursors from hydridosiloxane starting materials and then pyrolyzing these precursors to give rise to silicious ceramic materials. Si-H bonds present in the hydridosiloxane starting materials are catalytically activated, and the activated hydrogen atoms may then be replaced with nonhydrogen substituents. These preceramic materials are pyrolyzed in a selected atmosphere to give the desired ceramic product. Ceramic products which may be prepared by this technique include silica, silicon oxynitride, silicon carbide, metal silicates, and mullite.

Environment Conscious Ceramics (Ecoceramics): An Eco-Friendly Route to Advanced Ceramic Materials

NASA Technical Reports Server (NTRS)

Singh, M.

2001-01-01

Environment conscious ceramics (Ecoceramics) are a new class of materials, which can be produced with renewable natural resources (wood) or wood wastes (wood sawdust). This technology provides an eco-friendly route to advanced ceramic materials. Ecoceramics have tailorable properties and behave like ceramic materials manufactured by conventional approaches. Silicon carbide-based ecoceramics have been fabricated by reactive infiltration of carbonaceous preforms by molten silicon or silicon-refractory metal alloys. The fabrication approach, microstructure, and mechanical properties of SiC-based ecoceramics are presented.

7 CFR 58.710 - Fillers.

Code of Federal Regulations, 2010 CFR

2010-01-01

... strainer should be installed between the cooker and the filler. The hoppers of all filters shall be covered but the cover may have sight ports. If necessary, the hopper may have an agitator to prevent buildup... measurements. Product contact surfaces shall be of stainless steel or other corrosion resistant material...

Inorganic/organic nanocomposites: Reaching a high filler content without increasing viscosity using core-shell structured nanoparticles

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

Benhadjala, W., E-mail: warda.benhadjala@cea.fr; CEA, LETI, Minatec Campus, 38000 Grenoble; Gravoueille, M.

2015-11-23

Extensive research is being conducted on the development of inorganic/organic nanocomposites for a wide variety of applications in microelectronics, biotechnologies, photonics, adhesives, or optical coatings. High filler contents are usually required to fully optimize the nanocomposites properties. However, numerous studies demonstrated that traditional composite viscosity increases with increasing the filler concentration reducing therefore significantly the material processability. In this work, we synthesized inorganic/organic core-shell nanocomposites with different shell thicknesses. By reducing the shell thickness while maintaining a constant core size, the nanoparticle molecular mass decreases but the nanocomposite filler fraction is correlatively increased. We performed viscosity measurements, which clearly highlightedmore » that intrinsic viscosity of hybrid nanoparticles decreases as the molecular mass decreases, and thus, as the filler fraction increases, as opposed to Einstein predictions about the viscosity of traditional inorganic/polymer two-phase mixtures. This exceptional behavior, modeled by Mark-Houwink-Sakurada equation, proves to be a significant breakthrough for the development of industrializable nanocomposites with high filler contents.« less

Influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage restorations.

PubMed

Bakeman, E M; Rego, N; Chaiyabutr, Y; Kois, J C

2015-01-01

This study evaluated the influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage ceramic restorations. Forty extracted molars were allocated into four groups (n=10) to test for two variables: 1) the thickness of ceramic (1 mm or 2 mm) and 2) the ceramic materials (a lithium disilicate glass-ceramic [IPS e.max] or leucite-reinforced glass ceramic [IPS Empress]). All ceramic restorations were luted with resin cement (Variolink II) on the prepared teeth. These luted specimens were loaded to failure in a universal testing machine, in the compression mode, with a crosshead speed of 1.0 mm/min. The data were analyzed using two-way analysis of variance and the Tukey Honestly Significantly Different multiple comparison test (α =0.05). The fracture resistance revealed a significant effect for materials (p<0.001); however, the thickness of ceramic was not significant (p=0.074), and the interaction between the thickness of ceramic and the materials was not significant (p=0.406). Mean (standard deviation) fracture resistance values were as follows: a 2-mm thickness of a lithium disilicate bonded to tooth structure (2505 [401] N) revealed a significantly higher fracture resistance than did a 1-mm thickness of leucite-reinforced (1569 [452] N) and a 2-mm thickness of leucite-reinforced ceramic bonded to tooth structure (1716 [436] N) (p<0.05). There was no significant difference in fracture resistance values between a lithium disilicate ceramic at 1-mm thickness (2105 [567] N) and at 2-mm thickness. Using a lithium disilicate glass ceramic for partial coverage restoration significantly improved fracture resistance compared to using a leucite-reinforced glass ceramic. The thickness of ceramic had no significant effect on fracture resistance when the ceramics were bonded to the underlying tooth structure.

Free-standing oxide superconducting articles

DOEpatents

Wu, X.D.; Muenchausen, R.E.

1993-12-14

A substrate-free, free-standing epitaxially oriented superconductive film including a layer of a template material and a layer of a ceramic superconducting material is provided together with a method of making such a substrate-free ceramic superconductive film by coating an etchable material with a template layer, coating the template layer with a layer of a ceramic superconductive material, coating the layer of ceramic superconductive material with a protective material, removing the etchable material by an appropriate means so that the etchable material is separated from a composite structure including the template layer.

A quality by design approach to investigate the effect of mannitol and dicalcium phosphate qualities on roll compaction.

PubMed

Souihi, Nabil; Dumarey, Melanie; Wikström, Håkan; Tajarobi, Pirjo; Fransson, Magnus; Svensson, Olof; Josefson, Mats; Trygg, Johan

2013-04-15

Roll compaction is a continuous process for solid dosage form manufacturing increasingly popular within pharmaceutical industry. Although roll compaction has become an established technique for dry granulation, the influence of material properties is still not fully understood. In this study, a quality by design (QbD) approach was utilized, not only to understand the influence of different qualities of mannitol and dicalcium phosphate (DCP), but also to predict critical quality attributes of the drug product based solely on the material properties of that filler. By describing each filler quality in terms of several representative physical properties, orthogonal projections to latent structures (OPLS) was used to understand and predict how those properties affected drug product intermediates as well as critical quality attributes of the final drug product. These models were then validated by predicting product attributes for filler qualities not used in the model construction. The results of this study confirmed that the tensile strength reduction, known to affect plastic materials when roll compacted, is not prominent when using brittle materials. Some qualities of these fillers actually demonstrated improved compactability following roll compaction. While direct compression qualities are frequently used for roll compacted drug products because of their excellent flowability and good compaction properties, this study revealed that granules from these qualities were more poor flowing than the corresponding powder blends, which was not seen for granules from traditional qualities. The QbD approach used in this study could be extended beyond fillers. Thus any new compound/ingredient would first be characterized and then suitable formulation characteristics could be determined in silico, without running any additional experiments. Copyright © 2013 Elsevier B.V. All rights reserved.

Multilayer Coextrusion of Polymer Composites to Develop Organic Capacitors

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

Mondy, L.; Mrozek, R.; Rao, R.

Multilayer coextrusion is applied to produce a tape containing layers of alternating electrical properties to demonstrate the potential for using coextrusion to manufacture capacitors. To obtain the desired properties, we develop two filled polymer systems, one for conductive layers and one for dielectric layers. We describe numerical models used to help determine the material and processing parameters that impact processing and layer stability. These models help quantify the critical ratios of densities and viscosities of the two layers to maintain stable layers, as well as the effect of increasing the flow rate of one of the two materials. The conductingmore » polymer is based on polystyrene filled with a blend of low-melting-point eutectic metal and nickel particulate filler, as described by Mrozek et al. (2010). The appropriate concentrations of fillers are determined by balancing measured conductivity with processability in a twin screw extruder. Based on results of the numerical models and estimates of the viscosity of emulsions and suspensions, a dielectric layer composed of polystyrene filled with barium titanate is formulated. Despite the fact that the density of the dielectric filler is less than the metallic filler of the conductive phase, as well as rheological measurements that later showed that the dielectric formulation is not an ideal match to the viscosity of the conductive material, the two materials can be successfully coextruded if the flow rates of the two materials are not identical. A measurable capacitance of the layered structure is obtained.« less

Multilayer Coextrusion of Polymer Composites to Develop Organic Capacitors

DOE PAGES

Mondy, L.; Mrozek, R.; Rao, R.; ...

2015-05-29

Multilayer coextrusion is applied to produce a tape containing layers of alternating electrical properties to demonstrate the potential for using coextrusion to manufacture capacitors. To obtain the desired properties, we develop two filled polymer systems, one for conductive layers and one for dielectric layers. We describe numerical models used to help determine the material and processing parameters that impact processing and layer stability. These models help quantify the critical ratios of densities and viscosities of the two layers to maintain stable layers, as well as the effect of increasing the flow rate of one of the two materials. The conductingmore » polymer is based on polystyrene filled with a blend of low-melting-point eutectic metal and nickel particulate filler, as described by Mrozek et al. (2010). The appropriate concentrations of fillers are determined by balancing measured conductivity with processability in a twin screw extruder. Based on results of the numerical models and estimates of the viscosity of emulsions and suspensions, a dielectric layer composed of polystyrene filled with barium titanate is formulated. Despite the fact that the density of the dielectric filler is less than the metallic filler of the conductive phase, as well as rheological measurements that later showed that the dielectric formulation is not an ideal match to the viscosity of the conductive material, the two materials can be successfully coextruded if the flow rates of the two materials are not identical. A measurable capacitance of the layered structure is obtained.« less

Elastic and Sorption Characteristics of an Epoxy Binder in a Composite During Its Moistening

NASA Astrophysics Data System (ADS)

Aniskevich, K.; Glaskova, T.; Jansons, J.

2005-07-01

Results of an experimental investigation into the elastic and sorption characteristics of a model composite material (CM) — epoxy resin filled with LiF crystals — during its moistening are presented. Properties of the binder in the CM with different filler contents ( v f = 0, 0.05, 0.11, 0.23, 0.28, 0.33, 0.38, and 0.46) were evaluated indirectly by using known micromechanical models of CMs. It was revealed that, for the CM in a conditionally initial state, the elastic modulus of the binder in it and the filler microstrain (change in the interplanar distance in the crystals, measured by the X-ray method) as functions of filler content had the same character. The elastic modulus of the binder in the CM with a low filler content was equal to that for the binder in a block; the elastic modulus of the binder in the CM decreased with increasing filler content. The maximum (corresponding to water saturation of the CM) stresses in the binder and the filler microstresses as functions of filler content were of the same character. Moreover, the absolute values of maximum stresses in the binder and of filler microstresses coincided for high and low contents of the filler. At v f = 0.2-0. 3, the filler microstrains exceeded the stresses in the binder. The effect of moisture on the epoxy binder in the CM with a high filler content was not entirely reversible: the elastic characteristics of the binder increased, the diffusivity decreased, and the ultimate water content increased after a moistening-drying cycle.

Effect of monopolar radiofrequency treatment over soft-tissue fillers in an animal model: part 2.

PubMed

Shumaker, Peter R; England, Laura J; Dover, Jeffrey S; Ross, E Victor; Harford, Robert; Derienzo, Damian; Bogle, Melissa; Uebelhoer, Nathan; Jacoby, Mark; Pope, Karl

2006-03-01

Monopolar radiofrequency (RF) treatment is used by physicians to heat skin and promote tissue tightening and contouring. Cosmetic fillers are used to soften deep facial lines and wrinkles. Patients who have had dermal fillers implanted may also benefit from or are candidates for monopolar RF skin tightening. This study examined the effect of RF treatment on various dermal filler substances. This is the second part of a two-part study. A juvenile farm pig was injected with dermal fillers including cross-linked human collagen (Cosmoplast), polylactic acid (PLA) (Sculptra), liquid injectable silicone (Silikon 1000), calcium hydroxylapatite (CaHA) (Radiesse), and hyaluronic acid (Restylane). Skin injected with dermal fillers was RF-treated using a 1.5-cm2 treatment tip and treatment levels typically used in the clinical setting. Fillers were examined histologically 5 days, 2 weeks, or 1 month after treatment. Histological specimens were scored for inflammatory response, foreign body response, and fibrosis in order to assess the effect of treatment on early filler processes, such as inflammation and encapsulation. Each filler substance produced a characteristic inflammatory response. No immediate thermal effect of RF treatment was observed histologically. RF treatment resulted in statistically significant increases in the inflammatory, foreign body, and fibrotic responses associated with the filler substances. Monopolar RF treatment levels that are typically used in the clinical setting were employed in this animal study. RF treatment resulted in measurable and statistically significant histological changes associated with the various filler materials. Additional clinical and histological studies are required to determine the optimal timing of monopolar RF treatment and filler placement for maximal potential aesthetic outcome. 2006 Wiley-Liss, Inc.

Crosslinked hyaluronic acid dermal fillers: a comparison of rheological properties.

PubMed

Falcone, Samuel J; Berg, Richard A

2008-10-01

Temporary dermal fillers composed of crosslinked hyaluronic acid (XLHA) are space filling gels that are readily available in the United States and Europe. Several families of dermal fillers based on XLHA are now available and here we compare the physical and rheological properties of these fillers to the clinical effectiveness. The XLHA fillers are prepared with different crosslinkers, using HA isolated from different sources, have different particle sizes, and differ substantially in rheological properties. For these fillers, the magnitude of the complex viscosity, |eta*|, varies by a factor of 20, the magnitude of the complex rigidity modulus, |G*|, and the magnitude of the complex compliance, |J*| vary by a factor of 10, the percent elasticity varies from 58% to 89.9%, and the tan delta varies from 0.11 to 0.70. The available clinical data cannot be correlated with either the oscillatory dynamic or steady flow rotational rheological properties of the various fillers. However, the clinical data appear to correlate strongly with the total concentration of XLHA in the products and to a lesser extent with percent elasticity. Hence, our data suggest the following correlation: dermal filler persistence = [polymer] x [% elasticity] and the clinical persistence of a dermal filler composed of XLHA is dominated by the mass and elasticity of the material implanted. This work predicts that the development of future XLHA dermal filler formulations should focus on increasing the polymer concentration and elasticity to improve the clinical persistence.

Ceramic Laser Materials

PubMed Central

Sanghera, Jasbinder; Kim, Woohong; Villalobos, Guillermo; Shaw, Brandon; Baker, Colin; Frantz, Jesse; Sadowski, Bryan; Aggarwal, Ishwar

2012-01-01

Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements. PMID:28817044

Desire for penile girth enhancement and the effects of the self-injection of hyaluronic Acid gel.

PubMed

Coskuner, Enis Rauf; Canter, Halil Ibrahim

2012-07-01

Penile girth enhancement is a controversial subject but demands for enhancement are increasing steadily. Although various fillers have been widely used for soft tissue augmentation, there is no reliable material for this particular situation. Here we report a case of an acute hypersensitivity reaction in a man after his first self-injection of a filler material, which, he claimed, was hyaluronic acid gel for penile girth enhancement and glans penis augmentation.

Effect of overglazed and polished surface finishes on the compressive fracture strength of machinable ceramic materials.

PubMed

Asai, Tetsuya; Kazama, Ryunosuke; Fukushima, Masayoshi; Okiji, Takashi

2010-11-01

Controversy prevails over the effect of overglazing on the fracture strength of ceramic materials. Therefore, the effects of different surface finishes on the compressive fracture strength of machinable ceramic materials were investigated in this study. Plates prepared from four commercial brands of ceramic materials were either surface-polished or overglazed (n=10 per ceramic material for each surface finish), and bonded to flat surfaces of human dentin using a resin cement. Loads at failure were determined and statistically analyzed using two-way ANOVA and Bonferroni test. Although no statistical differences in load value were detected between polished and overglazed groups (p>0.05), the fracture load of Vita Mark II was significantly lower than those of ProCAD and IPS Empress CAD, whereas that of IPS e.max CAD was significantly higher than the latter two ceramic materials (p<0.05). It was concluded that overglazed and polished surfaces produced similar compressive fracture strengths irrespective of the machinable ceramic material tested, and that fracture strength was material-dependent.

Shape Memory Polyurethane Materials Containing Ferromagnetic Iron Oxide and Graphene Nanoplatelets

PubMed Central

Urban, Magdalena

2017-01-01

Intelligent materials, such as memory shape polymers, have attracted considerable attention due to wide range of possible applications. Currently, intensive research is underway, in matters of obtaining memory shape materials that can be actuated via inductive methods, for example with help of magnetic field. In this work, an attempt was made to develop a new polymer composite—polyurethane modified with graphene nanoplates and ferromagnetic iron oxides—with improved mechanical properties and introduced magnetic and memory shape properties. Based on the conducted literature review, gathered data were compared to the results of similar materials. Obtained materials were tested for their thermal, rheological, mechanical and shape memory properties. Structure of both fillers and composites were also analyzed using various spectroscopic methods. The addition of fillers to the polyurethane matrix improved the mechanical and shape memory properties, without having a noticeable impact on thermal properties. As it was expected, the high content of fillers caused a significant change in viscosity of filled prepolymers (during the synthesis stage). Each of the studied composites showed better mechanical properties than the unmodified polyurethanes. The addition of magnetic particles introduced additional properties to the composite, which could significantly expand the functionality of the materials developed in this work. PMID:28906445

Shape Memory Polyurethane Materials Containing Ferromagnetic Iron Oxide and Graphene Nanoplatelets.

PubMed

Urban, Magdalena; Strankowski, Michał

2017-09-14

Intelligent materials, such as memory shape polymers, have attracted considerable attention due to wide range of possible applications. Currently, intensive research is underway, in matters of obtaining memory shape materials that can be actuated via inductive methods, for example with help of magnetic field. In this work, an attempt was made to develop a new polymer composite-polyurethane modified with graphene nanoplates and ferromagnetic iron oxides-with improved mechanical properties and introduced magnetic and memory shape properties. Based on the conducted literature review, gathered data were compared to the results of similar materials. Obtained materials were tested for their thermal, rheological, mechanical and shape memory properties. Structure of both fillers and composites were also analyzed using various spectroscopic methods. The addition of fillers to the polyurethane matrix improved the mechanical and shape memory properties, without having a noticeable impact on thermal properties. As it was expected, the high content of fillers caused a significant change in viscosity of filled prepolymers (during the synthesis stage). Each of the studied composites showed better mechanical properties than the unmodified polyurethanes. The addition of magnetic particles introduced additional properties to the composite, which could significantly expand the functionality of the materials developed in this work.

Silver-hafnium braze alloy

DOEpatents

Stephens, Jr., John J.; Hosking, F. Michael; Yost, Frederick G.

2003-12-16

A binary allow braze composition has been prepared and used in a bonded article of ceramic-ceramic and ceramic-metal materials. The braze composition comprises greater than approximately 95 wt % silver, greater than approximately 2 wt % hafnium and less than approximately 4.1 wt % hafnium, and less than approximately 0.2 wt % trace elements. The binary braze alloy is used to join a ceramic material to another ceramic material or a ceramic material, such as alumina, quartz, aluminum nitride, silicon nitride, silicon carbide, and mullite, to a metal material, such as iron-based metals, cobalt-based metals, nickel-based metals, molybdenum-based metals, tungsten-based metals, niobium-based metals, and tantalum-based metals. A hermetic bonded article is obtained with a strength greater than 10,000 psi.

Composites from wood and plastics

Treesearch

Craig Clemons

2010-01-01

Composites made from thermoplastics and fillers or reinforcements derived from wood or other natural fibers are a dynamic research area encompassing a wide variety of composite materials. For example, as the use of biopolymers grows, wood and other natural fiber sources are being investigated as renewable sources of fillers and reinforcements to modify performance....

Flight-vehicle materials, structures, and dynamics - Assessment and future directions. Vol. 3 - Ceramics and ceramic-matrix composites

NASA Technical Reports Server (NTRS)

Levine, Stanley R. (Editor)

1992-01-01

The present volume discusses ceramics and ceramic-matrix composites in prospective aerospace systems, monolithic ceramics, transformation-toughened and whisker-reinforced ceramic composites, glass-ceramic matrix composites, reaction-bonded Si3N4 and SiC composites, and chemical vapor-infiltrated composites. Also discussed are the sol-gel-processing of ceramic composites, the fabrication and properties of fiber-reinforced ceramic composites with directed metal oxidation, the fracture behavior of ceramic-matrix composites (CMCs), the fatigue of fiber-reinforced CMCs, creep and rupture of CMCs, structural design methodologies for ceramic-based materials systems, the joining of ceramics and CMCs, and carbon-carbon composites.

Influence of the antagonist material on the wear of different composites using two different wear simulation methods.

PubMed

Heintze, S D; Zellweger, G; Cavalleri, A; Ferracane, J

2006-02-01

The aim of the study was to evaluate two ceramic materials as possible substitutes for enamel using two wear simulation methods, and to compare both methods with regard to the wear results for different materials. Flat specimens (OHSU n=6, Ivoclar n=8) of one compomer and three composite materials (Dyract AP, Tetric Ceram, Z250, experimental composite) were fabricated and subjected to wear using two different wear testing methods and two pressable ceramic materials as stylus (Empress, experimental ceramic). For the OHSU method, enamel styli of the same dimensions as the ceramic stylus were fabricated additionally. Both wear testing methods differ with regard to loading force, lateral movement of stylus, stylus dimension, number of cycles, thermocycling and abrasive medium. In the OHSU method, the wear facets (mean vertical loss) were measured using a contact profilometer, while in the Ivoclar method (maximal vertical loss) a laser scanner was used for this purpose. Additionally, the vertical loss of the ceramic stylus was quantified for the Ivoclar method. The results obtained from each method were compared by ANOVA and Tukey's test (p<0.05). To compare both wear methods, the log-transformed data were used to establish relative ranks between material/stylus combinations and assessed by applying the Pearson correlation coefficient. The experimental ceramic material generated significantly less wear in Tetric Ceram and Z250 specimens compared to the Empress stylus in the Ivoclar method, whereas with the OHSU method, no difference between the two ceramic antagonists was found with regard to abrasion or attrition. The wear generated by the enamel stylus was not statistically different from that generated by the other two ceramic materials in the OHSU method. With the Ivoclar method, wear of the ceramic stylus was only statistically different when in contact with Tetric Ceram. There was a close correlation between the attrition wear of the OHSU and the wear of the Ivoclar method (Pearson coefficient 0.83, p=0.01). Pressable ceramic materials can be used as a substitute for enamel in wear testing machines. However, material ranking may be affected by the type of ceramic material chosen. The attrition wear of the OHSU method was comparable with the wear generated with the Ivoclar method.

Ceramic matrix composite article and process of fabricating a ceramic matrix composite article

DOEpatents

Cairo, Ronald Robert; DiMascio, Paul Stephen; Parolini, Jason Robert

2016-01-12

A ceramic matrix composite article and a process of fabricating a ceramic matrix composite are disclosed. The ceramic matrix composite article includes a matrix distribution pattern formed by a manifold and ceramic matrix composite plies laid up on the matrix distribution pattern, includes the manifold, or a combination thereof. The manifold includes one or more matrix distribution channels operably connected to a delivery interface, the delivery interface configured for providing matrix material to one or more of the ceramic matrix composite plies. The process includes providing the manifold, forming the matrix distribution pattern by transporting the matrix material through the manifold, and contacting the ceramic matrix composite plies with the matrix material.

Brazilian Consensus Recommendation on the Use of Polymethylmethacrylate Filler in Facial and Corporal Aesthetics.

PubMed

Blanco Souza, Túlio Armanini; Colomé, Letícia Marques; Bender, Eduardo André; Lemperle, Gottfriede

2018-06-05

Considering that aesthetic benefits can be obtained with the use of permanent filling materials, this work focuses on the development of a consensus regarding the facial and corporal use of polymethylmethacrylate (PMMA) filler in Brazil. A questionnaire regarding PMMA treatment, which included items on the main indication, application site, volume of product applied, criteria for selection of the material, complications, contraindications, and individual professional experience, was distributed to the Expert Group members. In addition, the responses were summarized, constituting the starting point for the debate regarding the use of PMMA-based fillers on The First Brazilian PMMA Symposium to create a guideline to be followed in PMMA facial and corporal treatments. This survey involved 87,371 cases. PMMA treatment is recommended for restorative and aesthetic purposes in facial and corporal cases, particularly for facial balance. PMMA 30% filler is recommended in specific facial sites (nose, mentum, mandible angle, zygomatic arc, and malar). PMMA filler is contraindicated in other sites (lips) regardless of concentration. With regard to facial treatment, the juxtaperiostal is the application plane most recommended. For PMMA corporal application, intramuscular is the application plane most indicated, while intradermal and justadermal planes are contraindicated. The submuscular plane application is relative to PMMA filler concentration. The experts also inquired regarding the amount of PMMA recommended in each corporal site (50 mL in the calf, 100-150 mL in the gluteal region). These recommendations provide a guideline for physicians, supporting them to perform safe and efficacious treatment with PMMA fillers. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The effect of five kinds of surface treatment agents on the bond strength to various ceramics with thermocycle aging.

PubMed

Noda, Yukari; Nakajima, Masatoshi; Takahashi, Masahiro; Mamanee, Teerapong; Hosaka, Keiichi; Takagaki, Tomohiro; Ikeda, Masaomi; Foxton, Richard M; Tagami, Junji

2017-11-29

This study evaluated the effects of ceramic surface treatment agents on shear bond strengths to ceramic materials with and without thermocycling. Ceramic plates were prepared from feldspathic ceramic; AAA, lithium disilicate ceramic material; IPS e.max Press, zirconia ceramic; Lava. Ceramic surfaces were pretreated with one of five surface treatment agents (Clearfil PhotoBond mixed with Porcelainbond activator (PB), Clearfil SE One mixed with Porcelainbond activator (SO), Ceramic Primer (CP), Universal Primer (UP), Scotchbond Universal (SU)), and then a resin cement (Clapearl DC) was filled. After 0, 5,000, and 10,000 thermocycles, micro-shear bond strengths between ceramic-cement interfaces were determined. SU exhibited significantly lower initial bond strength to AAA and e.max than PB, SO, CP, and UP. For Lava, PB, SO, CP and SU exhibited higher initial bond strengths than UP. Thermocycles reduced bond strengths to all the ceramic materials with any surface treatment.

Degradation kinetics of ethylene-octene copolymer/wood flour biocomposites in dependence to filler content

NASA Astrophysics Data System (ADS)

Zykova, A. K.; Pantyukhov, P. V.; Monakhova, T. V.; Popov, A. A.

2017-06-01

This article is focused on thermal oxidative degradation and biodegradation in soil of biocomposites based on ethylene-octene copolymer (EOC), filled by wood flour (from 30 to 70% wt.), in dependence to the filler content. The study of oxidative degradation of composites was carried out at two temperatures (80 and 130°C respectively). The induction period and the rates of oxidation were determined. It was concluded that as filler content raises, the induction period increases. It can be explained by the higher specific area of composites in comparison with pure EOC. However, high filled composites (60 and 70 % of the filler) are oxidized with a huge induction period because polyphenols in the filler inhibit the oxidation process. Biodegradation test under laboratory conditions was carried out to investigate the biodegradability of the material. Composites with lower filler content have lower weight loss rate. Small particles are capsulated by polymer and are isolated from moisture and microorganisms. On the other hand, at a high filling of the composite small particles stick together and act as large ones. Such filler agglomerates are connected with each other and allow microorganisms to penetrate into the composite. It was concluded as filler content raises the mass loss increases.

The use of polyimide-modified aluminum nitride fillers in AlN@PI/Epoxy composites with enhanced thermal conductivity for electronic encapsulation

PubMed Central

Zhou, Yongcun; Yao, Yagang; Chen, Chia-Yun; Moon, Kyoungsik; Wang, Hong; Wong, Ching-ping

2014-01-01

Polymer modified fillers in composites has attracted the attention of numerous researchers. These fillers are composed of core-shell structures that exhibit enhanced physical and chemical properties that are associated with shell surface control and encapsulated core materials. In this study, we have described an apt method to prepare polyimide (PI)-modified aluminum nitride (AlN) fillers, AlN@PI. These fillers are used for electronic encapsulation in high performance polymer composites. Compared with that of untreated AlN composite, these AlN@PI/epoxy composites exhibit better thermal and dielectric properties. At 40 wt% of filler loading, the highest thermal conductivity of AlN@PI/epoxy composite reached 2.03 W/mK. In this way, the thermal conductivity is approximately enhanced by 10.6 times than that of the used epoxy matrix. The experimental results exhibiting the thermal conductivity of AlN@PI/epoxy composites were in good agreement with the values calculated from the parallel conduction model. This research work describes an effective pathway that modifies the surface of fillers with polymer coating. Furthermore, this novel technique improves the thermal and dielectric properties of fillers and these can be used extensively for electronic packaging applications. PMID:24759082

Cryogenic materials selection, availability, and cost considerations

NASA Technical Reports Server (NTRS)

Rush, H. F.

1983-01-01

The selection of structural alloys, composite materials, solder alloys, and filler materials for use in cryogenic models is discussed. In particular, materials testing programs conducted at Langley are described.

Dual-Component Gelatinous Peptide/Reactive Oligomer Formulations as Conduit Material and Luminal Filler for Peripheral Nerve Regeneration

PubMed Central

Kohn-Polster, Caroline; Bhatnagar, Divya; Woloszyn, Derek J.; Richtmyer, Matthew; Starke, Annett; Springwald, Alexandra H.; Franz, Sandra; Schulz-Siegmund, Michaela; Kaplan, Hilton M.; Kohn, Joachim; Hacker, Michael C.

2017-01-01

Toward the next generation of nerve guidance conduits (NGCs), novel biomaterials and functionalization concepts are required to address clinical demands in peripheral nerve regeneration (PNR). As a biological polymer with bioactive motifs, gelatinous peptides are promising building blocks. In combination with an anhydride-containing oligomer, a dual-component hydrogel system (cGEL) was established. First, hollow cGEL tubes were fabricated by a continuous dosing and templating process. Conduits were characterized concerning their mechanical strength, in vitro and in vivo degradation and biocompatibility. Second, cGEL was reformulated as injectable shear thinning filler for established NGCs, here tyrosine-derived polycarbonate-based braided conduits. Thereby, the formulation contained the small molecule LM11A-31. The biofunctionalized cGEL filler was assessed regarding building block integration, mechanical properties, in vitro cytotoxicity, and growth permissive effects on human adipose tissue-derived stem cells. A positive in vitro evaluation motivated further application of the filler material in a sciatic nerve defect. Compared to the empty conduit and pristine cGEL, the functionalization performed superior, though the autologous nerve graft remains the gold standard. In conclusion, LM11A-31 functionalized cGEL filler with extracellular matrix (ECM)-like characteristics and specific biochemical cues holds great potential to support PNR. PMID:28531139

Dual-Component Gelatinous Peptide/Reactive Oligomer Formulations as Conduit Material and Luminal Filler for Peripheral Nerve Regeneration.

PubMed

Kohn-Polster, Caroline; Bhatnagar, Divya; Woloszyn, Derek J; Richtmyer, Matthew; Starke, Annett; Springwald, Alexandra H; Franz, Sandra; Schulz-Siegmund, Michaela; Kaplan, Hilton M; Kohn, Joachim; Hacker, Michael C

2017-05-21

Toward the next generation of nerve guidance conduits (NGCs), novel biomaterials and functionalization concepts are required to address clinical demands in peripheral nerve regeneration (PNR). As a biological polymer with bioactive motifs, gelatinous peptides are promising building blocks. In combination with an anhydride-containing oligomer, a dual-component hydrogel system (cGEL) was established. First, hollow cGEL tubes were fabricated by a continuous dosing and templating process. Conduits were characterized concerning their mechanical strength, in vitro and in vivo degradation and biocompatibility. Second, cGEL was reformulated as injectable shear thinning filler for established NGCs, here tyrosine-derived polycarbonate-based braided conduits. Thereby, the formulation contained the small molecule LM11A-31. The biofunctionalized cGEL filler was assessed regarding building block integration, mechanical properties, in vitro cytotoxicity, and growth permissive effects on human adipose tissue-derived stem cells. A positive in vitro evaluation motivated further application of the filler material in a sciatic nerve defect. Compared to the empty conduit and pristine cGEL, the functionalization performed superior, though the autologous nerve graft remains the gold standard. In conclusion, LM11A-31 functionalized cGEL filler with extracellular matrix (ECM)-like characteristics and specific biochemical cues holds great potential to support PNR.

Method for adhesion of metal films to ceramics

DOEpatents

Lowndes, Douglas H.; Pedraza, Anthony J.; DeSilva, Melvin J.; Kumar, Rajagopalan A.

1997-01-01

Methods for making strongly bonded metal-ceramic materials. The methods include irradiating a portion of the surface of the ceramic material with a pulsed ultraviolet laser having an energy density sufficient to effect activation of the irradiated surface of the ceramic material so that adhesion of metals subsequently deposited onto the irradiated surface is substantially increased. Advantages of the invention include (i) the need for only a small number of laser pulses at relatively low focused energy density, (ii) a smoother substrate surface, (iii) activation of the laser-treated surface which provides a chemical bond between the surface and a metal deposited thereon, (iv) only low temperature annealing is required to produce the strong metal-ceramic bond; (v) the ability to obtain strong adhesion between ceramic materials and oxidation resistant metals; (vi) ability to store the laser treated ceramic materials for later deposition of metals thereon.

Method for adhesion of metal films to ceramics

DOEpatents

Lowndes, D.H.; Pedraza, A.J.; DeSilva, M.J.; Kumar, R.A.

1997-12-30

Methods for making strongly bonded metal-ceramic materials are disclosed. The methods include irradiating a portion of the surface of the ceramic material with a pulsed ultraviolet laser having an energy density sufficient to effect activation of the irradiated surface of the ceramic material so that adhesion of metals subsequently deposited onto the irradiated surface is substantially increased. Advantages of the invention include (i) the need for only a small number of laser pulses at relatively low focused energy density, (ii) a smoother substrate surface, (iii) activation of the laser-treated surface which provides a chemical bond between the surface and a metal deposited thereon, (iv) only low temperature annealing is required to produce the strong metal-ceramic bond; (v) the ability to obtain strong adhesion between ceramic materials and oxidation resistant metals; (vi) ability to store the laser treated ceramic materials for later deposition of metals thereon. 7 figs.

Alice's adventures in um-derland: Psycholinguistic sources of variation in disfluency production

PubMed Central

Fraundorf, Scott H.; Watson, Duane G.

2013-01-01

This study tests the hypothesis that three common types of disfluency (fillers, silent pauses, and repeated words) reflect variance in what strategies are available to the production system for responding to difficulty in language production. Participants' speech in a storytelling paradigm was coded for the three disfluency types. Repeats occurred most often when difficult material was already being produced and could be repeated, but fillers and silent pauses occurred most when difficult material was still being planned. Fillers were associated only with conceptual difficulties, consistent with the proposal that they reflect a communicative signal whereas silent pauses and repeats were also related to lexical and phonological difficulties. These differences are discussed in terms of different strategies available to the language production system. PMID:25339788

Challenges and Opportunities in Design, Fabrication, and Testing of High Temperature Joints in Ceramics and Ceramic Composites

NASA Technical Reports Server (NTRS)

Singh, M.; Levine, S. R. (Technical Monitor)

2001-01-01

Ceramic joining has been recognized as an enabling technology for successful utilization of advanced ceramics and composite materials. A number of joint design and testing issues have been discussed for ceramic joints in silicon carbide-based ceramics and fiber-reinforced composites. These joints have been fabricated using an affordable, robust ceramic joining technology (ARCJoinT). The microstructure and good high temperature mechanical capability (compressive and flexural strengths) of ceramic joints in silicon carbide-based ceramics and composite materials are reported.

Desire for Penile Girth Enhancement and the Effects of the Self-Injection of Hyaluronic Acid Gel

PubMed Central

Coskuner, Enis Rauf; Canter, Halil Ibrahim

2012-01-01

Penile girth enhancement is a controversial subject but demands for enhancement are increasing steadily. Although various fillers have been widely used for soft tissue augmentation, there is no reliable material for this particular situation. Here we report a case of an acute hypersensitivity reaction in a man after his first self-injection of a filler material, which, he claimed, was hyaluronic acid gel for penile girth enhancement and glans penis augmentation. PMID:23112518

Increasing of the lifetime of large forging dies by repairwelding

NASA Astrophysics Data System (ADS)

Duchek, M.; Koukolikova, M.; Kotous, J.; Majer, M.

2018-02-01

Repair welding is often used for rebuilding discarded or failed forging dies. It saves the cost of new tools. Increased useful life of repaired dies is another motivation for repair welding. This article focuses on the development of new filler materials for this purpose. The main goal was to prolong the life of tools of DIN 1.2714 material. Filler wires of two chemistries were made and several samples were experimentally welded. Metallographic and tribological analyses were carried out.

A Resorbable Antibiotic-Eluting Polymer Composite Bone Void Filler for Perioperative Infection Prevention in a Rabbit Radial Defect Model

PubMed Central

Brooks, Benjamin D.; Sinclair, Kristofer D.; Grainger, David W.; Brooks, Amanda E.

2015-01-01

Nearly 1.3 million total joint replacement procedures are performed in the United States annually, with numbers projected to rise exponentially in the coming decades. Although finite infection rates for these procedures remain consistently low, device-related infections represent a significant cause of implant failure, requiring secondary or revision procedures. Revision procedures manifest several-fold higher infection recurrence rates. Importantly, many revision surgeries, infected or not, require bone void fillers to support the host bone and provide a sufficient tissue bed for new hardware placement. Antibiotic-eluting bone void fillers (ABVF), providing both osteoconductive and antimicrobial properties, represent one approach for reducing rates of orthopedic device-related infections. Using a solvent-free, molten-cast process, a polymer-controlled antibiotic-eluting calcium carbonate hydroxyapatite (HAP) ceramic composite BVF (ABVF) was fabricated, characterized, and evaluated in vivo using a bacterial challenge in a rabbit radial defect window model. ABVF loaded with tobramycin eliminated the infectious burden in rabbits challenged with a clinically relevant strain of Staphylococcus aureus (inoculum as high as 107 CFU). Histological, microbiological, and radiographic methods were used to detail the effects of ABVF on microbial challenge to host bone after 8 weeks in vivo. In contrast to the HAP/BVF controls, which provided no antibiotic protection and required euthanasia 3 weeks post-operatively, tobramycin-releasing ABVF animals showed no signs of infection (clinical, microbiological, or radiographic) when euthanized at the 8-week study endpoint. ABVF sites did exhibit fibrous encapsulation around the implant at 8 weeks. Local antibiotic release from ABVF to orthopedic sites requiring bone void fillers eliminated the periprosthetic bacterial challenge in this 8-week in vivo study, confirming previous in vitro results. PMID:25815727

Superconductive articles including cerium oxide layer

DOEpatents

Wu, X.D.; Muenchausen, R.E.

1993-11-16

A ceramic superconductor comprising a metal oxide substrate, a ceramic high temperature superconductive material, and a intermediate layer of a material having a cubic crystal structure, said layer situated between the substrate and the superconductive material is provided, and a structure for supporting a ceramic superconducting material is provided, said structure comprising a metal oxide substrate, and a layer situated over the surface of the substrate to substantially inhibit interdiffusion between the substrate and a ceramic superconducting material deposited upon said structure. 7 figures.

Superconductive articles including cerium oxide layer

DOEpatents

Wu, Xin D.; Muenchausen, Ross E.

1993-01-01

A ceramic superconductor comprising a metal oxide substrate, a ceramic high temperature superconductive material, and a intermediate layer of a material having a cubic crystal structure, said layer situated between the substrate and the superconductive material is provided, and a structure for supporting a ceramic superconducting material is provided, said structure comprising a metal oxide substrate, and a layer situated over the surface of the substrate to substantially inhibit interdiffusion between the substrate and a ceramic superconducting material deposited upon said structure.

Effects of natural zeolite and ferric oxide to electromagnetic and reflection loss properties of polyurethane nanocomposite

NASA Astrophysics Data System (ADS)

Gultom, G.; Wirjosentono, B.; Ginting, M.; Sebayang, K.

2017-07-01

Microwave-absorptive polymeric composite materials are becoming important to protect interference of any communication systems due to increasing use of microwave-inducing devices. In this work, the microwave-absorptive polyurethane nanocomposites were prepared using natural zeolites of Sarulla North Sumatra and commercial ferric oxide as fillers. Weight ratios of the polyurethane to natural zeolite and ferric oxide were varied (90%:6%:4%; 80%:12%:8%; 70%:24%:6%) by weight. The fillers were prepared using ball milling technique and characterized for their particle size distributions using Particle Size Analyzer. The nanocomposites, prepared using in-situ reaction of polyethylene glycol, toluene diisocyanate and fillers. The complex permittivity (ε’and ε”) and complex permeability (μ’ and μ”) as electromagnetic properties were calculated using NRW method after collecting real and imaginary S parameter using Vector Network Analyzer measurement at X band frequency. Results show ratio of the fillers will affect the permeability, permittivity and reflection loss of the materials. The best reflection loss was shown -40.588 dB (>99 % absorption) at ratio for polyurethane : nanozeolite : ferric oxide (80%:12%:8%) by weight observed at 10.92 GHz. According to the measurement and calculation was shown the polyurethane filled with natural nanozeolite and ferric oxide is a good electromagnetic wave attenuation material.

Development of Ceramic Solid-State Laser Host Material

NASA Technical Reports Server (NTRS)

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

2009-01-01

Polycrystalline ceramic laser materials are gaining importance in the development of novel diode-pumped solid-state lasers. Compared to single-crystals, ceramic laser materials offer advantages in terms of ease of fabrication, shape, size, and control of dopant concentrations. Recently, we have developed Neodymium doped Yttria (Nd:Y2O3) as a solid-state ceramic laser material. A scalable production method was utilized to make spherical non agglomerated and monodisperse metastable ceramic powders of compositions that were used to fabricate polycrystalline ceramic material components. This processing technique allowed for higher doping concentrations without the segregation problems that are normally encountered in single crystalline growth. We have successfully fabricated undoped and Neodymium doped Yttria material up to 2" in diameter, Ytterbium doped Yttria, and erbium doped Yttria. We are also in the process of developing other sesquioxides such as scandium Oxide (Sc2O3) and Lutesium Oxide (Lu2O3) doped with Ytterbium, erbium and thulium dopants. In this paper, we present our initial results on the material, optical, and spectroscopic properties of the doped and undoped sesquioxide materials. Polycrystalline ceramic lasers have enormous potential applications including remote sensing, chem.-bio detection, and space exploration research. It is also potentially much less expensive to produce ceramic laser materials compared to their single crystalline counterparts because of the shorter fabrication time and the potential for mass production in large sizes.

Failure modes and materials design for biomechanical layer structures

NASA Astrophysics Data System (ADS)

Deng, Yan

Ceramic materials are finding increasing usage in the area of biomechanical replacements---dental crowns, hip and bone implants, etc.---where strength, wear resistance, biocompatibility, chemical durability and even aesthetics are critical issues. Aesthetic ceramic crowns have been widely used in dentistry to replace damaged or missing teeth. However, the failure rates of ceramic crowns, especially all-ceramic crowns, can be 1%˜6% per year, which is not satisfactory to patients. The materials limitations and underlying fracture mechanisms of these prostheses are not well understood. In this thesis, fundamental fracture and damage mechanisms in model dental bilayer and trilayer structures are studied. Principle failure modes are identified from in situ experimentation and confirmed by fracture mechanics analysis. In bilayer structures of ceramic/polycarbonate (representative of ceramic crown/dentin structure), three major damage sources are identified: (i) top-surface cone cracks or (ii) quasiplasticity, dominating in thick ceramic bilayers; (iii) bottom-surface radial cracks, dominating in thin ceramic bilayers. Critical load P for each damage mode are measured in six dental ceramics: Y-TZP zirconia, glass-infiltrated zirconia and alumina (InCeram), glass-ceramic (Empress II), Porcelain (Mark II and Empress) bonded to polymer substrates, as a function of ceramic thickness d in the range of 100 mum to 10 mm. P is found independent of d for mode (i) and (ii), but has a d 2 relations for mode (iii)---bottom surface radial cracking. In trilayer structures of glass/core-ceramic/polycarbonate (representing veneer porcelain/core/dentin structures), three inner fracture origins are identified: radial cracks from the bottom surface in the (i) first and (ii) second layers; and (iii) quasiplasticity in core-ceramic layer. The role of relative veneer/core thickness, d1/d 2 and materials properties is investigated for three core materials with different modulus (114--270GPa) and strength (400--1400MPa): Y-TZP zirconia, InCeram alumina and Empress II glass-ceramic. Explicit relations for the critical loads P to produce these different damage modes in bilayer and trilayer structures are developed in terms of basic material properties (modulus E, strength, hardness H and toughness T) and geometrical variables (thickness d and contact sphere radius r). These experimentally validated relations are used to design of optimal material combinations for improved fracture resistance and to predict mechanical performance of current dental materials.

The Micromorphological Research of the Internal Structure of Chairside CAD/CAM Materials by the Method of Scanning Impulse Acoustic Microscopy (SIAM).

PubMed

Goryainova, Kristina E; Morokov, Egor S; Retinskaja, Marina V; Rusanov, Fedor S; Apresyan, Samvel V; Lebedenko, Igor Yu

2018-01-01

The aim of the present work was to compare the elastic properties and internal structure of 4 different CAD/CAM chairside materials, by the method of Scanning Impulse Acoustic Microscopy (SIAM). Four chairside CAD/CAM materials with different structures from hybrid ceramic (VITA Enamic, VITA Zahnfabrik), feldspatic ceramic (VITABlocs Mark II, VITA Zahnfabrik), leucite glass-ceramic (IPS Empress CAD, Ivoclar Vivadent) and PMMA (Telio CAD, Ivoclar Vivadent) were examined by Scanning Impulse Acoustic Microscope (SIAM). The results of micromorphological research of CAD/CAM chairside materials using SIAM method showed differences between the internal structures of these materials. The internal structure of feldspatic and glass-ceramic samples revealed the presence of pores with different sizes, from 10 to 100 microns; the structure of polymer materials rendered some isolated defects, while in the structure of hybrid material, defects were not found. Based on the results obtained from the present study, in cases of chairside production of dental crowns, it would be advisable to give preference to the blocks of hybrid ceramics. Such ceramics devoid of quite large porosity, glazing for CAD/CAM crowns made from leucite glass-ceramic and feldspatic ceramic may be an option. For these purposes, commercially available special muffle furnace for clinical and laboratory individualization and glazing of ceramic prostheses were provided. Further studies are needed to confirm the evidence emerging from the present research.

Microstructure-based modelling of arbitrary deformation histories of filler-reinforced elastomers

NASA Astrophysics Data System (ADS)

Lorenz, H.; Klüppel, M.

2012-11-01

A physically motivated theory of rubber reinforcement based on filler cluster mechanics is presented considering the mechanical behaviour of quasi-statically loaded elastomeric materials subjected to arbitrary deformation histories. This represents an extension of a previously introduced model describing filler induced stress softening and hysteresis of highly strained elastomers. These effects are referred to the hydrodynamic reinforcement of rubber elasticity due to strain amplification by stiff filler clusters and cyclic breakdown and re-aggregation (healing) of softer, already damaged filler clusters. The theory is first developed for the special case of outer stress-strain cycles with successively increasing maximum strain. In this more simple case, all soft clusters are broken at the turning points of the cycle and the mechanical energy stored in the strained clusters is completely dissipated, i.e. only irreversible stress contributions result. Nevertheless, the description of outer cycles involves already all material parameters of the theory and hence they can be used for a fitting procedure. In the general case of an arbitrary deformation history, the cluster mechanics of the material is complicated due to the fact that not all soft clusters are broken at the turning points of a cycle. For that reason additional reversible stress contributions considering the relaxation of clusters upon retraction have to be taken into account for the description of inner cycles. A special recursive algorithm is developed constituting a frame of the mechanical response of encapsulated inner cycles. Simulation and measurement are found to be in fair agreement for CB and silica filled SBR/BR and EPDM samples, loaded in compression and tension along various deformation histories.

Method of sintering ceramic materials

DOEpatents

Holcombe, Cressie E.; Dykes, Norman L.

1992-01-01

A method for sintering ceramic materials is described. A ceramic article is coated with layers of protective coatings such as boron nitride, graphite foil, and niobium. The coated ceramic article is embedded in a container containing refractory metal oxide granules and placed within a microwave oven. The ceramic article is heated by microwave energy to a temperature sufficient to sinter the ceramic article to form a densified ceramic article having a density equal to or greater than 90% of theoretical density.

Translucency of dental ceramics with different thicknesses.

PubMed

Wang, Fu; Takahashi, Hidekazu; Iwasaki, Naohiko

2013-07-01

The increased use of esthetic restorations requires an improved understanding of the translucent characteristics of ceramic materials. Ceramic translucency has been considered to be dependent on composition and thickness, but less information is available about the translucent characteristics of these materials, especially at different thicknesses. The purpose of this study was to investigate the relationship between translucency and the thickness of different dental ceramics. Six disk-shaped specimens of 8 glass ceramics (IPS e.max Press HO, MO, LT, HT, IPS e.max CAD LT, MO, AvanteZ Dentin, and Trans) and 5 specimens of 5 zirconia ceramics (Cercon Base, Zenotec Zr Bridge, Lava Standard, Lava Standard FS3, and Lava Plus High Translucency) were prepared following the manufacturers' instructions and ground to a predetermined thickness with a grinding machine. A spectrophotometer was used to measure the translucency parameters (TP) of the glass ceramics, which ranged from 2.0 to 0.6 mm, and of the zirconia ceramics, which ranged from 1.0 to 0.4 mm. The relationship between the thickness and TP of each material was evaluated using a regression analysis (α=.05). The TP values of the glass ceramics ranged from 2.2 to 25.3 and the zirconia ceramics from 5.5 to 15.1. There was an increase in the TP with a decrease in thickness, but the amount of change was material dependent. An exponential relationship with statistical significance (P<.05) between the TP and thickness was found for both glass ceramics and zirconia ceramics. The translucency of dental ceramics was significantly influenced by both material and thickness. The translucency of all materials increased exponentially as the thickness decreased. All of the zirconia ceramics evaluated in the present study showed some degree of translucency, which was less sensitive to thickness compared to that of the glass ceramics. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Phase-change materials handbook

NASA Technical Reports Server (NTRS)

Hale, D. V.; Hoover, M. J.; Oneill, M. J.

1972-01-01

Handbook describes relationship between phase-change materials and more conventional thermal control techniques and discusses materials' space and terrestrial applications. Material properties of most promising phase-change materials and purposes and uses of metallic filler materials in phase-change material composites are provided.

Industrial waste utilization for foam concrete

NASA Astrophysics Data System (ADS)

Krishnan, Gokul; Anand, K. B.

2018-02-01

Foam concrete is an emerging and useful construction material - basically a cement based slurry with at least 10% of mix volume as foam. The mix usually containing cement, filler (usually sand) and foam, have fresh densities ranging from 400kg/m3 to 1600kg/m3. One of the main drawbacks of foam concrete is the large consumption of fine sand as filler material. Usage of different solid industrial wastes as fillers in foam concrete can reduce the usage of fine river sand significantly and make the work economic and eco-friendly. This paper aims to investigate to what extent industrial wastes such as bottom ash and quarry dust can be utilized for making foam concrete. Foam generated using protein based agent was used for preparing and optimizing (fresh state properties). Investigation to find the influence of design density and air-void characteristics on the foam concrete strength shows higher strength for bottom ash mixes due to finer air void distribution. Setting characteristics of various mix compositions are also studied and adoption of Class C flyash as filler demonstrated capability of faster setting.

High Temperature Tolerant Ceramic Composites Having Porous Interphases

DOEpatents

Kriven, Waltraud M.; Lee, Sang-Jin

2005-05-03

In general, this invention relates to a ceramic composite exhibiting enhanced toughness and decreased brittleness, and to a process of preparing the ceramic composite. The ceramic composite comprises a first matrix that includes a first ceramic material, preferably selected from the group including alumina (Al2O3), mullite (3Al2O3.2SiO2), yttrium aluminate garnet (YAG), yttria stabilized zirconia (YSZ), celsian (BaAl2Si2O8) and nickel aluminate (NiAl2O4). The ceramic composite also includes a porous interphase region that includes a substantially non-sinterable material. The non-sinterable material can be selected to include, for example, alumina platelets. The platelets lie in random 3-D orientation and provide a debonding mechanism, which is independent of temperature in chemically compatible matrices. The non-sinterable material induces constrained sintering of a ceramic powder resulting in permanent porosity in the interphase region. For high temperature properties, addition of a sinterable ceramic powder to the non-sinterable material provides sufficiently weak debonding interphases. The ceramic composite can be provided in a variety of forms including a laminate, a fibrous monolith, and a fiber-reinforced ceramic matrix. In the laminated systems, intimate mixing of strong versus tough microstructures were tailored by alternating various matrix-to-interphase thickness ratios to provide the bimodal laminate.

Free-standing oxide superconducting articles

DOEpatents

Wu, Xin D.; Muenchausen, Ross E.

1993-01-01

A substrate-free, free-standing epitaxially oriented superconductive film including a layer of a template material and a layer of a ceramic superconducting material is provided together with a method of making such a substrate-free ceramic superconductive film by coating an etchable material with a template layer, coating the template layer with a layer of a ceramic superconductive material, coating the layer of ceramic superconductive material with a protective material, removing the etchable material by an appropriate means so that the etchable material is separated from a composite structure including the template lay This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

Acoustic emission as a screening tool for ceramic matrix composites

NASA Astrophysics Data System (ADS)

Ojard, Greg; Goberman, Dan; Holowczak, John

2017-02-01

Ceramic matrix composites are composite materials with ceramic fibers in a high temperature matrix of ceramic or glass-ceramic. This emerging class of materials is viewed as enabling for efficiency improvements in many energy conversion systems. The key controlling property of ceramic matrix composites is a relatively weak interface between the matrix and the fiber that aids crack deflection and fiber pullout resulting in greatly increased toughness over monolithic ceramics. United Technologies Research Center has been investigating glass-ceramic composite systems as a tool to understand processing effects on material performance related to the performance of the weak interface. Changes in the interface have been shown to affect the mechanical performance observed in flexural testing and subsequent microstructural investigations have confirmed the performance (or lack thereof) of the interface coating. Recently, the addition of acoustic emission testing during flexural testing has aided the understanding of the characteristics of the interface and its performance. The acoustic emission onset stress changes with strength and toughness and this could be a quality tool in screening the material before further development and use. The results of testing and analysis will be shown and additional material from other ceramic matrix composite systems may be included to show trends.

The stability mechanisms of an injectable calcium phosphate ceramic suspension

PubMed Central

Fatimi, Ahmed; Tassin, Jean-François; Axelos, Monique A. V.; Weiss, Pierre

2010-01-01

Calcium phosphate ceramics are widely used as bone substitutes in dentistry and orthopedic applications. For minimally invasive surgery an injectable calcium phosphate ceramic suspension (ICPCS) was developed. It consists in a biopolymer (hydroxypropylmethylcellulose: HPMC) as matrix and bioactive calcium phosphate ceramics (biphasic calcium phosphate: BCP) as fillers. The stability of the suspension is essential to this generation of “ready to use” injectable biomaterial. But, during storage, the particles settle down. The engineering sciences have long been interested in models describing the settling (or sedimentation) of particles in viscous fluids. Our work is dedicated to the comprehension of the effect of the formulation on the stability of calcium phosphate suspension before and after steam sterilization. The rheological characterization revealed the macromolecular behavior of the suspending medium. The investigations of settling kinetics showed the influence of the BCP particle size and the HPMC concentration on the settling velocity and sediment compactness before and after sterilization. To decrease the sedimentation process, the granule size has to be smaller and the polymer concentration has to increase. A much lower sedimentation velocity, as compared to Stokes law, is observed and interpreted in terms of interactions between the polymer network in solution and the particles. This experimentation highlights the granules spacer property of hydrophilic macromolecules that is a key issue for interconnection control, one of the better ways to improve osteoconduction and bioactivity. PMID:20229185

The stability mechanisms of an injectable calcium phosphate ceramic suspension.

PubMed

Fatimi, Ahmed; Tassin, Jean-François; Axelos, Monique A V; Weiss, Pierre

2010-06-01

Calcium phosphate ceramics are widely used as bone substitutes in dentistry and orthopedic applications. For minimally invasive surgery an injectable calcium phosphate ceramic suspension (ICPCS) was developed. It consists in a biopolymer (hydroxypropylmethylcellulose: HPMC) as matrix and bioactive calcium phosphate ceramics (biphasic calcium phosphate: BCP) as fillers. The stability of the suspension is essential to this generation of "ready to use" injectable biomaterial. But, during storage, the particles settle down. The engineering sciences have long been interested in models describing the settling (or sedimentation) of particles in viscous fluids. Our work is dedicated to the comprehension of the effect of the formulation on the stability of calcium phosphate suspension before and after steam sterilization. The rheological characterization revealed the macromolecular behavior of the suspending medium. The investigations of settling kinetics showed the influence of the BCP particle size and the HPMC concentration on the settling velocity and sediment compactness before and after sterilization. To decrease the sedimentation process, the granule size has to be smaller and the polymer concentration has to increase. A much lower sedimentation velocity, as compared to Stokes law, is observed and interpreted in terms of interactions between the polymer network in solution and the particles. This experimentation highlights the granules spacer property of hydrophilic macromolecules that is a key issue for interconnection control, one of the better ways to improve osteoconduction and bioactivity.

Wear characteristics of current aesthetic dental restorative CAD/CAM materials: two-body wear, gloss retention, roughness and Martens hardness.

PubMed

Mörmann, Werner H; Stawarczyk, Bogna; Ender, Andreas; Sener, Beatrice; Attin, Thomas; Mehl, Albert

2013-04-01

This study determined the two-body wear and toothbrushing wear parameters, including gloss and roughness measurements and additionally Martens hardness, of nine aesthetic CAD/CAM materials, one direct resin-based nanocomposite plus that of human enamel as a control group. Two-body wear was investigated in a computer-controlled chewing simulator (1.2 million loadings, 49N at 1.7Hz; 3000 thermocycles 5/50°C). Each of the 11 groups consisted of 12 specimens and 12 enamel antagonists. Quantitative analysis of wear was carried out with a 3D-surface analyser. Gloss and roughness measurements were evaluated using a glossmeter and an inductive surface profilometer before and after abrasive toothbrushing of machine-polished specimens. Additionally Martens hardness was measured. Statistically significant differences were calculated with one-way ANOVA (analysis of variance). Statistically significant differences were found for two-body wear, gloss, surface roughness and hardness. Zirconium dioxide ceramics showed no material wear and low wear of the enamel antagonist. Two-body wear of CAD/CAM-silicate and -lithium disilicate ceramics, -hybrid ceramics and -nanocomposite as well as direct nanocomposite did not differ significantly from that of human enamel. Temporary polymers showed significantly higher material wear than permanent materials. Abrasive toothbrushing significantly reduced gloss and increased roughness of all materials except zirconium dioxide ceramics. Gloss retention was highest with zirconium dioxide ceramics, silicate ceramics, hybrid ceramics and nanocomposites. Temporary polymers showed least gloss retention. Martens hardness differed significantly among ceramics, between ceramics and composites, and between resin composites and acrylic block materials as well. All permanent aesthetic CAD/CAM block materials tested behave similarly or better with respect to two-body wear and toothbrushing wear than human enamel, which is not true for temporary polymer CAD/CAM block materials. Ceramics show the best gloss retention compared to hybrid ceramics, composites and acrylic polymers. Copyright © 2013 Elsevier Ltd. All rights reserved.

Reduction of liquid metal embrittlement in copper-brazed stainless steel joints

NASA Astrophysics Data System (ADS)

Uhlig, T.; Fedorov, V.; Elßner, M.; Wagner, G.; Weis, S.

2017-03-01

Due to its very good formability and the low raw material cost, pure copper in form of foils is commonly used to braze plate heat exchangers made of stainless steel. The difference in the electrochemical potentials of brazing filler and base material leads to corrosion effects in contact with electrolytes. This may lead to leakages, which decrease the reliability of the heat exchanger during service in potable water. The dissolution of the emerging corrosion products of brazing filler and base material induces the migration of heavy metal ions, such as Cu2+ and Ni2+, into the potable water. The so-called liquid metal embrittlement, which takes place during the brazing process, may intensify the corrosion. The brazing filler infiltrates the stainless steel along the grain boundaries and causes an embrittlement. This paper deals with the determination of the grain boundary erosion dependent on the degree of deformation and heat treatment of the stainless steel AISI 316L.

Processing and characterization of polyols plasticized-starch reinforced with microcrystalline cellulose.

PubMed

Rico, M; Rodríguez-Llamazares, S; Barral, L; Bouza, R; Montero, B

2016-09-20

Biocomposites suitable for short-life applications such as food packaging were prepared by melt processing and investigated. Biocomposites studied are wheat starch plasticized with two different molecular weight polyols (glycerol and sorbitol) and reinforced with various amounts of microcrystalline cellulose. The effect of the plasticizer type and the filler amount on the processing properties, the crystallization behavior and morphology developed for the materials, and the influence on thermal stability, dynamic mechanical properties and water absorption behavior were investigated. Addition of microcrystalline cellulose led to composites with good filler-matrix adhesion where the stiffness and resistance to humidity absorption were improved. The use of sorbitol as a plasticizer of starch also improved the stiffness and water uptake behavior of the material as well as its thermal stability. Biodegradable starch-based materials with a wide variety of properties can be tailored by varying the polyol plasticizer type and/or by adding microcrystalline cellulose filler. Copyright © 2016 Elsevier Ltd. All rights reserved.

On dissimilar metal welding of AISI4140 and AISI410 by GTAW

NASA Astrophysics Data System (ADS)

Velu, M.; Dixit, Shantanu; Choure, Shubham

2017-11-01

This paper presents the results of metallurgical and mechanical examinations of Gas Tungsten Arc Welding of dissimilar steels AISI4140 and AISI410. Two different filler materials viz., ERNiCr3 and SS410 were used. The various properties of the weldments made using the fillers were compared to select the most appropriate one to get the sound joint. The ultimate tensile and yield strengths of the weldments of SS410 were greater than those of ERNiCr3. The fracture occurred at the weld in weldments made with ERNiCr3, whereas, in the base metal of AISI410 for weldments made with SS410. Microstructure of fusion zone of ERNiCr3 was fully austenitic. Microhardness values in the weld of SS410 were higher and fluctuating compared to those in the weld of ERNiCr3. From this research work, it shall be concluded that SS410 is the best filler material to weld these base materials.

Filler features and their effects on wear and degree of conversion of particulate dental resin composites.

PubMed

Turssi, C P; Ferracane, J L; Vogel, K

2005-08-01

Based on the incomplete understanding on how filler features influence the wear resistance and monomer conversion of resin composites, this study sought to evaluate whether materials containing different shapes and combinations of size of filler particles would perform similarly in terms of three-body abrasion and degree of conversion. Twelve experimental monomodal, bimodal or trimodal composites containing either spherical or irregular shaped fillers ranging from 100 to 1500 nm were examined. Wear testings were conducted in the OHSU wear machine (n = 6) and quantified after 10(5) cycles using a profilometer. Degree of conversion (DC) was measured by FTIR spectrometry at the surface of the composites (n = 6). Data sets were analyzed using one-way Anova and Tukey's test at a significance level of 0.05. Filler size and geometry was found to have a significant effect on wear resistance and DC of composites. At specific sizes and combinations, the presence of small filler particles, either spherical or irregular, may aid in enhancing the wear resistance of composites, without compromising the percentage of reacted carbon double bonds.

Bioactive ceramic-based materials with designed reactivity for bone tissue regeneration

PubMed Central

Ohtsuki, Chikara; Kamitakahara, Masanobu; Miyazaki, Toshiki

2009-01-01

Bioactive ceramics have been used clinically to repair bone defects owing to their biological affinity to living bone; i.e. the capability of direct bonding to living bone, their so-called bioactivity. However, currently available bioactive ceramics do not satisfy every clinical application. Therefore, the development of novel design of bioactive materials is necessary. Bioactive ceramics show osteoconduction by formation of biologically active bone-like apatite through chemical reaction of the ceramic surface with surrounding body fluid. Hence, the control of their chemical reactivity in body fluid is essential to developing novel bioactive materials as well as biodegradable materials. This paper reviews novel bioactive materials designed based on chemical reactivity in body fluid. PMID:19158015

Finite-Element Modeling of a Damaged Pipeline Repaired Using the Wrap of a Composite Material

NASA Astrophysics Data System (ADS)

Lyapin, A. A.; Chebakov, M. I.; Dumitrescu, A.; Zecheru, G.

2015-07-01

The nonlinear static problem of FEM modeling of a damaged pipeline repaired by a composite material and subjected to internal pressure is considered. The calculation is carried out using plasticity theory for the pipeline material and considering the polymeric filler and the composite wrap. The level of stresses in various zones of the structure is analyzed. The most widespread alloy used for oil pipelines is selected as pipe material. The contribution of each component of the pipeline-filler-wrap system to the level of stresses is investigated. The effect of the number of composite wrap layers is estimated. The results obtained allow one to decrease the costs needed for producing test specimens.

Method of sintering ceramic materials

DOEpatents

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

1992-11-17

A method for sintering ceramic materials is described. A ceramic article is coated with layers of protective coatings such as boron nitride, graphite foil, and niobium. The coated ceramic article is embedded in a container containing refractory metal oxide granules and placed within a microwave oven. The ceramic article is heated by microwave energy to a temperature sufficient to sinter the ceramic article to form a densified ceramic article having a density equal to or greater than 90% of theoretical density. 2 figs.

Cytocompatibility and response of osteoblastic-like cells to starch-based polymers: effect of several additives and processing conditions.

PubMed

Gomes, M E; Reis, R L; Cunha, A M; Blitterswijk, C A; de Bruijn, J D

2001-07-01

This work reports on the biocompatibility evaluation of new biodegradable starch-based polymers that are under consideration for use in orthopaedic temporary applications and as tissue engineering scaffolds. It has been shown in previous works that by using these polymers it is both possible to produce polymer/hydroxyapatite (HA) composites (with or without the use of coupling agents) with mechanical properties matching those of the human bone, and to obtain 3D structures generated by solid blowing agents, that are suitable for tissue engineering applications. This study was focused on establishing the influence of several additives (ceramic fillers, blowing agents and coupling agents) and processing methods/conditions on the biocompatibility of the materials described above. The cytotoxicity of the materials was evaluated using cell culture methods, according to ISO/EN 109935 guidelines. A cell suspension of human osteosarcoma cells (HOS) was also seeded on a blend of corn starch with ethylene vinyl alcohol (SEVA-C) and on SEVA-C/HA composites, in order to have a preliminary indication on cell adhesion and proliferation on the materials surface. In general, the obtained results show that all the different materials based on SEVA-C, (which are being investigated for use in several biomedical applications), as well as all the additives (including the novel coupling agents) and different processing methods required to obtain the different properties/products, can be used without inducing a cytotoxic behaviour to the developed biomaterials.

An Investigation of Reliability Models for Ceramic Matrix Composites and their Implementation into Finite Element Codes

NASA Technical Reports Server (NTRS)

Duffy, Stephen F.

1998-01-01

The development of modeling approaches for the failure analysis of ceramic-based material systems used in high temperature environments was the primary objective of this research effort. These materials have the potential to support many key engineering technologies related to the design of aeropropulsion systems. Monolithic ceramics exhibit a number of useful properties such as retention of strength at high temperatures, chemical inertness, and low density. However, the use of monolithic ceramics has been limited by their inherent brittleness and a large variation in strength. This behavior has motivated material scientists to reinforce the monolithic material with a ceramic fiber. The addition of a second ceramic phase with an optimized interface increases toughness and marginally increases strength. The primary purpose of the fiber is to arrest crack growth, not to increase strength. The material systems of interest in this research effort were laminated ceramic matrix composites, as well as two- and three- dimensional fabric reinforced ceramic composites. These emerging composite systems can compete with metals in many demanding applications. However, the ongoing metamorphosis of ceramic composite material systems, and the lack of standardized design data has in the past tended to minimize research efforts related to structural analysis. Many structural components fabricated from ceramic matrix composites (CMC) have been designed by "trial and error." The justification for this approach lies in the fact that during the initial developmental phases for a material system fabrication issues are paramount. Emphasis is placed on demonstrating feasibility rather than fully understanding the processes controlling mechanical behavior. This is understandable during periods of rapid improvements in material properties for any composite system. But to avoid the ad hoc approach, the analytical methods developed under this effort can be used to develop rational structural design protocols.

Method for sealing an oxygen transport membrane assembly

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

Gonzalez, Javier E.; Grant, Arthur F.

An improved method of sealing a ceramic part to a solid part made of ceramic, metal, cermet or a ceramic coated metal is provided. The improved method includes placing a bond agent comprising an Al 2O 3 and SiO 2 based glass-ceramic material and organic binder material on adjoining surfaces of the ceramic part and the solid part. The assembly is heated to a first target temperature that removes or dissolves the organic binder material from the bond agent and the assembly is subjected to a second induction heating step at a temperature ramp rate of between about 100.degree. C.more » and 200.degree. C. per minute to temperatures where the glass-ceramic material flows and wets the interface between adjoining surfaces. The assembly is rapidly cooled at a cooling rate of about 140.degree. C. per minute or more to induce nucleation and re-crystallization of the glass-ceramic material to form a dense, durable and gas-tight seal.« less

Advanced functional polymers for regenerative and therapeutic dentistry.

PubMed

Lai, W-F; Oka, K; Jung, H-S

2015-07-01

Use of ceramics and polymers continues to dominate clinical procedures in modern dentistry. Polymers have provided the basis for adhesives, tissue void fillers, and artificial replacements for whole teeth. They have been remarkably effective in the clinic at restoration of major dental functions after damage or loss of teeth. With the rapid development of polymer science, dental materials science has significantly lagged behind in harnessing these advanced polymer products. What they offer is new and unique properties superior to traditional polymers and crucially a range of properties that more closely match natural biomaterials. Therefore, we should pursue more vigorously the benefits of advanced polymers in dentistry. In this review, we highlight how the latest generation of advanced polymers will enhance the application of materials in the dental clinic using numerous promising examples. Polymers have a broad range of applications in modern dentistry. Some major applications are to construct frameworks that mimic the precise structure of tissues, to restore tooth organ function, and to deliver bioactive agents to influence cell behavior from the inside. The future of polymers in dentistry must include all these new enhancements to increase biological and clinical effectiveness beyond what can be achieved with traditional biomaterials. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Calcium Orthophosphates as Bioceramics: State of the Art

PubMed Central

Dorozhkin, Sergey V.

2010-01-01

In the late 1960s, much interest was raised in regard to biomedical applications of various ceramic materials. A little bit later, such materials were named bioceramics. This review is limited to bioceramics prepared from calcium orthophosphates only, which belong to the categories of bioactive and bioresorbable compounds. There have been a number of important advances in this field during the past 30–40 years. Namely, by structural and compositional control, it became possible to choose whether calcium orthophosphate bioceramics were biologically stable once incorporated within the skeletal structure or whether they were resorbed over time. At the turn of the millennium, a new concept of calcium orthophosphate bioceramics—which is able to promote regeneration of bones—was developed. Presently, calcium orthophosphate bioceramics are available in the form of particulates, blocks, cements, coatings, customized designs for specific applications and as injectable composites in a polymer carrier. Current biomedical applications include artificial replacements for hips, knees, teeth, tendons and ligaments, as well as repair for periodontal disease, maxillofacial reconstruction, augmentation and stabilization of the jawbone, spinal fusion and bone fillers after tumor surgery. Exploratory studies demonstrate potential applications of calcium orthophosphate bioceramics as scaffolds, drug delivery systems, as well as carriers of growth factors, bioactive peptides and/or various types of cells for tissue engineering purposes. PMID:24955932

Ceramic substrate including thin film multilayer surface conductor

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

Wolf, Joseph Ambrose; Peterson, Kenneth A.

2017-05-09

A ceramic substrate comprises a plurality of ceramic sheets, a plurality of inner conductive layers, a plurality of vias, and an upper conductive layer. The ceramic sheets are stacked one on top of another and include a top ceramic sheet. The inner conductive layers include electrically conductive material that forms electrically conductive features on an upper surface of each ceramic sheet excluding the top ceramic sheet. The vias are formed in each of the ceramic sheets with each via being filled with electrically conductive material. The upper conductive layer includes electrically conductive material that forms electrically conductive features on anmore » upper surface of the top ceramic sheet. The upper conductive layer is constructed from a stack of four sublayers. A first sublayer is formed from titanium. A second sublayer is formed from copper. A third sublayer is formed from platinum. A fourth sublayer is formed from gold.« less

Cladding material, tube including such cladding material and methods of forming the same

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

Garnier, John E.; Griffith, George W.

A multi-layered cladding material including a ceramic matrix composite and a metallic material, and a tube formed from the cladding material. The metallic material forms an inner liner of the tube and enables hermetic sealing of thereof. The metallic material at ends of the tube may be exposed and have an increased thickness enabling end cap welding. The metallic material may, optionally, be formed to infiltrate voids in the ceramic matrix composite, the ceramic matrix composite encapsulated by the metallic material. The ceramic matrix composite includes a fiber reinforcement and provides increased mechanical strength, stiffness, thermal shock resistance and highmore » temperature load capacity to the metallic material of the inner liner. The tube may be used as a containment vessel for nuclear fuel used in a nuclear power plant or other reactor. Methods for forming the tube comprising the ceramic matrix composite and the metallic material are also disclosed.« less

Collagen/hydroxyapatite composite materials with desired ceramic properties.

PubMed

Andronescu, Ecaterina; Voicu, Georgeta; Ficai, Maria; Mohora, Ioana Anita; Trusca, Roxana; Ficai, Anton

2011-01-01

Our purpose was to obtain and characterize some collagen/hydroxyapatite (COLL/HA) hybrid composite materials with desired ceramic properties. The ceramic properties of these materials were achieved by combining two drying methods: controlled air drying at 30°C followed by freeze-drying. Through the function of the air drying times, the materials morphology varies from porous materials (when the materials are freeze-dried) up to dense materials (when the materials are air-dried), while the combined drying allows us to obtain an intermediary morphology. The composite materials intended to be used as bone grafts and in a drug delivery system were characterized by XRD, FTIR, SEM, and also by determining the ceramic properties by using the Arthur method. The ceramic properties of these COLL/HA composite materials vary in large range, for instance the density of the materials varies from 0.06 up to 1.5 g/cm(3) while the porosity varies from 96.5% down to 27.5%.

Modeling the Mechanical Behavior of Ceramic Matrix Composite Materials

NASA Technical Reports Server (NTRS)

Jordan, William

1998-01-01

Ceramic matrix composites are ceramic materials, such as SiC, that have been reinforced by high strength fibers, such as carbon. Designers are interested in using ceramic matrix composites because they have the capability of withstanding significant loads while at relatively high temperatures (in excess of 1,000 C). Ceramic matrix composites retain the ceramic materials ability to withstand high temperatures, but also possess a much greater ductility and toughness. Their high strength and medium toughness is what makes them of so much interest to the aerospace community. This work concentrated on two different tasks. The first task was to do an extensive literature search into the mechanical behavior of ceramic matrix composite materials. This report contains the results of this task. The second task was to use this understanding to help interpret the ceramic matrix composite mechanical test results that had already been obtained by NASA. Since the specific details of these test results are subject to the International Traffic in Arms Regulations (ITAR), they are reported in a separate document (Jordan, 1997).

Development and Sliding Wear Response of Epoxy Composites Filled with Coal Mine Overburden Material

NASA Astrophysics Data System (ADS)

Das, Prithika; Satapathy, Alok; Mishra, M. K.

2018-03-01

The paper reports on development and characterization of epoxy based composites filled with micro-sized mine overburden material. Coal mine overburden material is typically highly heterogeneous and is considered as waste material. For excavating each ton of coal, roughly 5 tons of overburden materials are removed and is dumped nearby occupying large space. Gainful utilization of this waste is a major challenge. In the present work, this material is used as filler materials in making a new class of epoxy matrix composites. Composites with different weight proportions of fillers (0, 10, 20, 30 and 40) wt. % are prepared by hand layup technique. Compression tests are performed as per corresponding ASTM standards to assess the compressive strength of these composites. Further, dry sliding tests are performed following ASTM G99 standards using a pin on disk machine. A design of experiment approach based on Taguchi’s L16 orthogonal arrays is adopted. Tests are performed at different sliding velocities for multiple sliding distances under varying normal loads. Specific wear rates of the composites under different test conditions are obtained. The analysis of the test results revealed that the filler content and the sliding velocity are the most predominant control factors affecting the wear rate. This work thus, opens up a new avenue for the value added utilization of coal mine overburden material.

The Micromorphological Research of the Internal Structure of Chairside CAD/CAM Materials by the Method of Scanning Impulse Acoustic Microscopy (SIAM)

PubMed Central

Goryainova, Kristina E.; Morokov, Egor S.; Retinskaja, Marina V.; Rusanov, Fedor S.; Apresyan, Samvel V.; Lebedenko, Igor Yu.

2018-01-01

Aim: The aim of the present work was to compare the elastic properties and internal structure of 4 different CAD/CAM chairside materials, by the method of Scanning Impulse Acoustic Microscopy (SIAM). Methods: Four chairside CAD/CAM materials with different structures from hybrid ceramic (VITA Enamic, VITA Zahnfabrik), feldspatic ceramic (VITABlocs Mark II, VITA Zahnfabrik), leucite glass-ceramic (IPS Empress CAD, Ivoclar Vivadent) and PMMA (Telio CAD, Ivoclar Vivadent) were examined by Scanning Impulse Acoustic Microscope (SIAM). Results: The results of micromorphological research of CAD/CAM chairside materials using SIAM method showed differences between the internal structures of these materials. The internal structure of feldspatic and glass-ceramic samples revealed the presence of pores with different sizes, from 10 to 100 microns; the structure of polymer materials rendered some isolated defects, while in the structure of hybrid material, defects were not found. Conclusion: Based on the results obtained from the present study, in cases of chairside production of dental crowns, it would be advisable to give preference to the blocks of hybrid ceramics. Such ceramics devoid of quite large porosity, glazing for CAD/CAM crowns made from leucite glass-ceramic and feldspatic ceramic may be an option. For these purposes, commercially available special muffle furnace for clinical and laboratory individualization and glazing of ceramic prostheses were provided. Further studies are needed to confirm the evidence emerging from the present research. PMID:29492178

Performance of Ceramics in Severe Environments

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.; Fox, Dennis S.; Smialek, James L.; Deliacorte, Christopher; Lee, Kang N.

2005-01-01

Ceramics are generally stable to higher temperatures than most metals and alloys. Thus the development of high temperature structural ceramics has been an area of active research for many years. While the dream of a ceramic heat engine still faces many challenges, niche markets are developing for these materials at high temperatures. In these applications, ceramics are exposed not only to high temperatures but also aggressive gases and deposits. In this chapter we review the response of ceramic materials to these environments. We discuss corrosion mechanisms, the relative importance of a particular corrodent, and, where available, corrosion rates. Most of the available corrosion information is on silicon carbide (SIC) and silicon nitride (Si3N4) monolithic ceramics. These materials form a stable film of silica (SO2) in an oxidizing environment. We begin with a discussion of oxidation of these materials and proceed to the effects of other corrodents such as water vapor and salt deposits. We also discuss oxidation and corrosion of other ceramics: precurser derived ceramics, ceramic matrix composites (CMCs), ceramics which form oxide scales other than silica, and oxide ceramics. Many of the corrosion issues discussed can be mitigated with refractory oxide coatings and we discuss the current status of this active area of research. Ultimately, the concern of corrosion is loss of load bearing capability. We discuss the effects of corrosive environments on the strength of ceramics, both monolithic and composite. We conclude with a discussion of high temperature wear of ceramics, another important form of degradation at high temperatures.

Zero valent zinc nanoparticles promote neuroglial cell proliferation: A biodegradable and conductive filler candidate for nerve regeneration.

PubMed

Aydemir Sezer, Umran; Ozturk, Kevser; Aru, Basak; Yanıkkaya Demirel, Gulderen; Sezer, Serdar; Bozkurt, Mehmet Recep

2017-01-01

Regeneration of nerve, which has limited ability to undergo self-healing, is one of the most challenging areas in the field of tissue engineering. Regarding materials used in neuroregeneration, there is a recent trend toward electrically conductive materials. It has been emphasized that the capacity of conductive materials to regenerate such tissue having limited self-healing ability improves their clinical utility. However, there have been concerns about the safety of materials or fillers used for conductance due to their lack of degradability. Here, we attempt to use poly(Ɛ-caprolactone) (PCL) matrix consisting of varying proportions of zero valent zinc nanoparticles (Zn NPs) via electrospinning. These conductive, biodegradable, and bioactive materials efficiently promoted neuroglial cell proliferation depending on the amount of Zn NPs present in the PCL matrix. Chemical characterizations indicated that the incorporated Zn NPs do not interact with the PCL matrix chemically and that the Zn NPs improved the tensile properties of the PCL matrix. All composites exhibited linear conductivity under in vitro conditions. In vitro cell culture studies were performed to determine the cytotoxicity and proliferative efficiency of materials containing different proportions of Zn NPs. The results were obtained to explore new conductive fillers that can promote tissue regeneration.

Degradation of strength properties of epoxy resin filled with natural-based particles

NASA Astrophysics Data System (ADS)

Valášek, Petr; Habrová, Karolína; Müller, Miroslav

2018-05-01

Degradation of polymeric materials can be considered as a limiting factor for their use. Mechanical characteristics of epoxy resins are reduced, for example, by the action and changes of temperature or humidity. Degradation also occurs in composite systems where the epoxy resins function as matrices, i.e. in polymer composite materials. If a natural filler is used together with the epoxy resin, we refer to these materials as biocomposites, where also the natural character of the filler material greatly affects the degradation process. The paper focuses on the description of the shear strength of the resin filled with particles prepared from the seeds of dates of Phoenix Dactylifera plant. The degradation was evaluated experimentally in laboratory conditions via the climatic chamber. The experiment describes composites with a particle size of filler 100-200 μm with a concentration of 5 - 10 wt%. As the number of degradation cycles increased, the tensile strength of both the unfilled and the filled epoxy resin decreased. After 5 weeks, the drop was up to 50%. The presence of the particles did not significantly affect the shear strength compared to the non-filled resin. The described way of utilization of the natural-based particles is the possibility of material utilization of secondary natural materials.

An optical coherence tomography investigation of materials defects in ceramic fixed partial dental prostheses

NASA Astrophysics Data System (ADS)

Sinescu, Cosmin; Negrutiu, Meda; Hughes, Michael; Bradu, Adrian; Todea, Carmen; Rominu, Mihai; Laissue, Philippe L.; Podoleanu, Adrian Gh.

2008-04-01

Metal ceramic and integral ceramic fixed partial prostheses are mainly used in the frontal part of the dental arch because for esthetics reasons. The masticatory stress may induce fractures of the bridges. There are several factors that are associated with the stress state created in ceramic restorations, including: thickness of ceramic layers, mechanical properties of the materials, elastic modulus of the supporting substrate material, direction, magnitude and frequency of applied load, size and location of occlusal contact areas, residual stresses induced by processing or pores, restoration-cement interfacial defects and environmental defects. The fractures of these bridges lead to functional, esthetic and phonetic disturbances which finally render the prosthetic treatment inefficient. The purpose of this study is to evaluate the capability of optical coherence tomography (OCT) in detection and analysis of possible material defects in metal-ceramic and integral ceramic fixed partial dentures.

Crystallization behaviors and seal application of basalt based glass-ceramics

NASA Astrophysics Data System (ADS)

Ateş, A.; Önen, U.; Ercenk, E.; Yılmaz, Ş.

2017-02-01

Basalt based glass-ceramics were prepared by conventional melt-quenching technique and subsequently converted to glass-ceramics by a controlled nucleation and crystallization process. Glass materials were obtained by melt at 1500°C and quenched in cold water. The powder materials were made by milling and spin coating. The powders were applied on the 430 stainless steel interconnector material, and heat treatment was carried out. The interface characteristics between the glass-ceramic layer and interconnector were investigated by using X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The results showed that the basalt base glass-ceramic sealant material exhibited promising properties to use for SOFC.

Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

DOEpatents

Meek, T.T.; Blake, R.D.

1985-04-03

A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate.

Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

DOEpatents

Meek, Thomas T.; Blake, Rodger D.

1987-01-01

A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate.

Nuclear Technology. Course 28: Welding Inspection. Module 28-8, Filler Metal Control.

ERIC Educational Resources Information Center

Espy, John

This eighth in a series of ten modules for a course titled Welding Inspection describes controls necessary to place the proper electrode or rod at each welding station. More specifically, the module describes use of the American Welding Society specifications, control of weld filler material after receipt from the supplier, and methods of ensuring…

Particle-filled microporous materials

DOEpatents

McAllister, Jerome W.; Kinzer, Kevin E.; Mrozinski, James S.; Johnson, Eric J.; Dyrud, James F.

1990-01-01

A microporous particulate-filled thermoplastic polymeric article is provided. The article can be in the form of a film, a fiber, or a tube. The article has a thermoplastic polymeric structure having a plurality of interconnected passageways to provide a network of communicating pores. The microporous structure contains discrete submicron or low micron-sized particulate filler, the particulate filler being substantially non-agglomerated.

Particle-filled microporous materials

DOEpatents

McAllister, Jerome W.; Kinzer, Kevin E.; Mrozinski, James S.; Johnson, Eric J.

1992-07-14

A microporous particulate-filled thermoplastic polymeric article is provided. The article can be in the form of a film, a fiber, or a tube. The article has a thermoplastic polymeric structure having a plurality of interconnected passageways to provide a network of communicating pores. The microporous structure contains discrete submicron or low micron-sized particulate filler, the particulate filler being substantially non-agglomerated.

Inorganic-organic separators for alkaline batteries

NASA Technical Reports Server (NTRS)

Sheibley, D. W. (Inventor)

1978-01-01

A flexible separator is reported for use between the electrodes of Ni-Cd and Ni-Zn batteries using alkaline electrolytes. The separator was made by coating a porous substrate with a battery separator composition. The coating material included a rubber-based resin copolymer, a plasticizer and inorganic and organic fillers which comprised 55% by volume or less of the coating as finally dried. One or more of the filler materials, whether organic or inorganic, is preferably active with the alkaline electrolyte to produce pores in the separator coating. The plasticizer was an organic material which is hydrolyzed by the alkaline electrolyte to improve conductivity of the separator coating.

Structural Ceramics Database

National Institute of Standards and Technology Data Gateway

SRD 30 NIST Structural Ceramics Database (Web, free access)   The NIST Structural Ceramics Database (WebSCD) provides evaluated materials property data for a wide range of advanced ceramics known variously as structural ceramics, engineering ceramics, and fine ceramics.

Ceramic Nanocomposites from Tailor-Made Preceramic Polymers

PubMed Central

Mera, Gabriela; Gallei, Markus; Bernard, Samuel; Ionescu, Emanuel

2015-01-01

The present Review addresses current developments related to polymer-derived ceramic nanocomposites (PDC-NCs). Different classes of preceramic polymers are briefly introduced and their conversion into ceramic materials with adjustable phase compositions and microstructures is presented. Emphasis is set on discussing the intimate relationship between the chemistry and structural architecture of the precursor and the structural features and properties of the resulting ceramic nanocomposites. Various structural and functional properties of silicon-containing ceramic nanocomposites as well as different preparative strategies to achieve nano-scaled PDC-NC-based ordered structures are highlighted, based on selected ceramic nanocomposite systems. Furthermore, prospective applications of the PDC-NCs such as high-temperature stable materials for thermal protection systems, membranes for hot gas separation purposes, materials for heterogeneous catalysis, nano-confinement materials for hydrogen storage applications as well as anode materials for secondary ion batteries are introduced and discussed in detail. PMID:28347023

Effects of Ceramic Density and Sintering Temperature on the Mechanical Properties of a Novel Polymer-Infiltrated Ceramic-Network Zirconia Dental Restorative (Filling) Material.

PubMed

Li, Weiyan; Sun, Jian

2018-05-10

BACKGROUND Polymer-infiltrated ceramic-network (PICN) dental material is a new and practical development in orthodontics. Sintering is the process of forming a stable solid mass from a powder by heating without melting. The aim of this study was to evaluate the effects of sintering temperature on the mechanical properties of a PICN zirconia dental material. MATERIAL AND METHODS A dense zirconia ceramic and four PICN zirconia dental materials, with varying porosities, were sintered at three different temperatures; 12 PICN zirconia dental materials based on these porous ceramics were prepared, as well as a pure polymer. After the specimen preparation, flexural strength and elastic modulus values were measured using the three-point bending test, and fracture toughness were determined by the single-edge notched beam (SENB) method. The Vickers hardness test method was used with an indentation strength (IS) test. Scanning electron microscopy (SEM) was used to examine the microstructure of the ceramic surface and the fracture surface. RESULTS Mechanical properties of the PICN dental materials, including flexural strength, elastic modulus, fracture toughness, and hardness, were more similar to the properties of natural teeth when compared with traditional dental ceramic materials, and were affected by the density and sintering temperature. SEM showed that the porous ceramic network became cohesive and that the length of cracks in the PICN dental material was reduced. CONCLUSIONS PICN zirconia dental materials were characterized by similar mechanical properties to natural dental tissues, but further studies are required continue to improve the similarities with natural human enamel and dentin.

Effects of Ceramic Density and Sintering Temperature on the Mechanical Properties of a Novel Polymer-Infiltrated Ceramic-Network Zirconia Dental Restorative (Filling) Material

PubMed Central

Li, Weiyan

2018-01-01

Background Polymer-infiltrated ceramic-network (PICN) dental material is a new and practical development in orthodontics. Sintering is the process of forming a stable solid mass from a powder by heating without melting. The aim of this study was to evaluate the effects of sintering temperature on the mechanical properties of a PICN zirconia dental material. Material/Methods A dense zirconia ceramic and four PICN zirconia dental materials, with varying porosities, were sintered at three different temperatures; 12 PICN zirconia dental materials based on these porous ceramics were prepared, as well as a pure polymer. After the specimen preparation, flexural strength and elastic modulus values were measured using the three-point bending test, and fracture toughness were determined by the single-edge notched beam (SENB) method. The Vickers hardness test method was used with an indentation strength (IS) test. Scanning electron microscopy (SEM) was used to examine the microstructure of the ceramic surface and the fracture surface. Results Mechanical properties of the PICN dental materials, including flexural strength, elastic modulus, fracture toughness, and hardness, were more similar to the properties of natural teeth when compared with traditional dental ceramic materials, and were affected by the density and sintering temperature. SEM showed that the porous ceramic network became cohesive and that the length of cracks in the PICN dental material was reduced. Conclusions PICN zirconia dental materials were characterized by similar mechanical properties to natural dental tissues, but further studies are required continue to improve the similarities with natural human enamel and dentin. PMID:29746449

Effect of Impact Angle on Ceramic Deposition Behavior in Composite Cold Spray: A Finite-Element Study

NASA Astrophysics Data System (ADS)

Chakrabarty, Rohan; Song, Jun

2017-10-01

During the cold spraying of particle-reinforced metal matrix composite coatings (ceramic and metal particles mixture) on metal substrates, ceramic particles may either get embedded in the substrate/deposited coating or may rebound from the substrate surface. In this study, the dependence of the ceramic rebounding phenomenon on the spray angle and its effect on substrate erosion have been analyzed using finite-element analysis. From the numerical simulations, it was found that the ceramic particle density and substrate material strength played the major roles in determining the embedding and ceramic retention behavior. Substrate material erosion also influenced the ceramic retention, and the material loss increased as the impact angles decreased from normal. In general, the results concluded that decreasing the impact angle promoted the retention possibility of ceramics in the substrate. This study provides new theoretical insights into the effect of spray angles on the ceramic retention and suggests a new route toward optimizing the spraying process to increase the ceramic retention in composite coatings cold spray.

Tribology of ceramics: Report of the Committee on Tribology of Ceramics

NASA Technical Reports Server (NTRS)

1988-01-01

The current state of knowledge of ceramic surface structures, composition, and reactivity is reviewed. The tribological requirements of advanced mechanical systems now being deployed (in particular, heat engines) exceed the capabilities of traditional metallic-based materials because of the high temperatures encountered. Advanced ceramic materials for such applications are receiving intense scrutiny, but there is a lack of understanding of the properties and behavior of ceramic surfaces and the influence of processing on the properties of ceramics is described. The adequacy of models, ranging form atomic to macro, to describe and to predict ceramic friction and wear are discussed, as well as what is known about lubrication at elevated temperatures. From this analysis, recommendations are made for coordination, research, and development that will lead to better performance of ceramic materials in tribological systems.

Corrosion of Ceramic Materials

NASA Technical Reports Server (NTRS)

Opila, Elizabeth J.; Jacobson, Nathan S.

1999-01-01

Non-oxide ceramics are promising materials for a range of high temperature applications. Selected current and future applications are listed. In all such applications, the ceramics are exposed to high temperature gases. Therefore it is critical to understand the response of these materials to their environment. The variables to be considered here include both the type of ceramic and the environment to which it is exposed. Non-oxide ceramics include borides, nitrides, and carbides. Most high temperature corrosion environments contain oxygen and hence the emphasis of this chapter will be on oxidation processes.

Interphase for ceramic matrix composites reinforced by non-oxide ceramic fibers

NASA Technical Reports Server (NTRS)

DiCarlo, James A. (Inventor); Bhatt, Ramakrishna (Inventor); Morscher, Gregory N. (Inventor); Yun, Hee-Mann (Inventor)

2008-01-01

A ceramic matrix composite material is disclosed having non-oxide ceramic fibers, which are formed in a complex fiber architecture by conventional textile processes; a thin mechanically weak interphase material, which is coated on the fibers; and a non-oxide or oxide ceramic matrix, which is formed within the interstices of the interphase-coated fiber architecture. During composite fabrication or post treatment, the interphase is allowed to debond from the matrix while still adhering to the fibers, thereby providing enhanced oxidative durability and damage tolerance to the fibers and the composite material.

Segmented ceramic liner for induction furnaces

DOEpatents

Gorin, Andrew H.; Holcombe, Cressie E.

1994-01-01

A non-fibrous ceramic liner for induction furnaces is provided by vertically stackable ring-shaped liner segments made of ceramic material in a light-weight cellular form. The liner segments can each be fabricated as a single unit or from a plurality of arcuate segments joined together by an interlocking mechanism. Also, the liner segments can be formed of a single ceramic material or can be constructed of multiple concentric layers with the layers being of different ceramic materials and/or cellular forms. Thermomechanically damaged liner segments are selectively replaceable in the furnace.

Segmented ceramic liner for induction furnaces

DOEpatents

Gorin, A.H.; Holcombe, C.E.

1994-07-26

A non-fibrous ceramic liner for induction furnaces is provided by vertically stackable ring-shaped liner segments made of ceramic material in a light-weight cellular form. The liner segments can each be fabricated as a single unit or from a plurality of arcuate segments joined together by an interlocking mechanism. Also, the liner segments can be formed of a single ceramic material or can be constructed of multiple concentric layers with the layers being of different ceramic materials and/or cellular forms. Thermomechanically damaged liner segments are selectively replaceable in the furnace. 5 figs.

A novel tool for the prediction of tablet sticking during high speed compaction.

PubMed

Abdel-Hamid, Sameh; Betz, Gabriele

2012-01-01

During tableting, capping is a problem of cohesion while sticking is a problem of adhesion. Sticking is a multi-composite problem; causes are either material or machine related. Nowadays, detecting such a problem is a pre-requisite in the early stages of development. The aim of our study was to investigate sticking by radial die-wall pressure monitoring guided by compaction simulation. This was done by using the highly sticking drug; Mefenamic acid (MA) at different drug loadings with different fillers compacted at different pressures and speeds. By increasing MA loading, we found that viscoelastic fillers showed high residual radial pressure after compaction while plastic/brittle fillers showed high radial pressure during compaction, p < 0.05. Visually, plastic/brittle fillers showed greater tendencies for adhesion to punches than viscoelastic fillers while the later showed higher tendencies for adhesion to the die-wall. This was confirmed by higher values of axial stress transmission for plastic/brittle than viscoelastic fillers (higher punch surface/powder interaction), and higher residual die-wall and ejection forces for viscoelastic than plastic/brittle fillers, p < 0.05. Take-off force was not a useful tool to estimate sticking due to cohesive failure of the compacts. Radial die-wall pressure monitoring is suggested as a robust tool to predict sticking.

Influence of implant abutment material on the color of different ceramic crown systems.

PubMed

Dede, Doğu Ömür; Armağanci, Arzu; Ceylan, Gözlem; Celik, Ersan; Cankaya, Soner; Yilmaz, Burak

2016-11-01

Ceramics are widely used for anterior restorations; however, clinical color reproduction still constitutes a challenge particularly when the ceramic crowns are used on titanium implant abutments. The purpose of this in vitro study was to investigate the effect of implant abutment material on the color of different ceramic material systems. Forty disks (11×1.5 mm, shade A2) were fabricated from medium-opacity (mo) and high-translucency (ht) lithium disilicate (IPS e.max) blocks, an aluminous ceramic (VITA In-Ceram Alumina), and a zirconia (Zirkonzahn) ceramic system. Disks were fabricated to represent 3 different implant abutments (zirconia, gold-palladium, and titanium) and dentin (composite resin, A2 shade) as background (11×2 mm). Disk-shaped composite resin specimens in A2 shade were fabricated to represent the cement layer. The color measurements of ceramic specimens were made on composite resin abutment materials using a spectrophotometer. CIELab color coordinates were recorded, and the color coordinates measured on composite resin background served as the control group. Color differences (ΔE 00 ) between the control and test groups were calculated. The data were analyzed with 2-way analysis of variance (ANOVA) and compared with the Tukey HSD test (α=.05). The ceramics system, abutment material, and their interaction were significant for ΔE 00 values (P<.001). Clinically unacceptable results (ΔE 00 >2.25) were observed for lithium disilicate ceramics on titanium abutments (2.46-2.50). The ΔE 00 values of lithium disilicate ceramics for gold-palladium and titanium abutments were significantly higher than for other groups (P<.05). The color results (ΔE 00 >2.25) of an implant-supported lithium disilicate ceramic restoration may be clinically unacceptable if it is fabricated over a titanium abutment. Zirconia may be a more suitable abutment material for implant-supported ceramic restorations. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Process for strengthening silicon based ceramics

DOEpatents

Kim, Hyoun-Ee; Moorhead, A. J.

1993-01-01

A process for strengthening silicon based ceramic monolithic materials and omposite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400.degree. C. The process results in a dense, tightly adherent silicon containing oxide layer that heals, blunts , or otherwise negates the detrimental effect of strength limiting flaws on the surface of the ceramic body.

Process for strengthening silicon based ceramics

DOEpatents

Kim, Hyoun-Ee; Moorhead, A. J.

1993-04-06

A process for strengthening silicon based ceramic monolithic materials and omposite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400.degree. C. The process results in a dense, tightly adherent silicon containing oxide layer that heals, blunts , or otherwise negates the detrimental effect of strength limiting flaws on the surface of the ceramic body.

The Influence of Processing and the Polymorphism of Lignocellulosic Fillers on the Structure and Properties of Composite Materials—A Review

PubMed Central

Paukszta, Dominik; Borysiak, Slawomir

2013-01-01

Cellulose is the most important and the most abundant plant natural polymer. It shows a number of interesting properties including those making it attractive as a filler of composite materials with a thermoplastic polymer matrix. Production of such composite materials, meeting the standards of green technology, has increased from 0.36 million tons in 2007 to 2.33 million tons in 2012. It is predicted that by 2020 their production will reach 3.45 million tons. Production of biocomposites with lignocellulosic components poses many problems that should be addressed. This paper is a review of the lignocellulosic materials currently used as polymer fillers. First, the many factors determining the macroscopic properties of such composites are described, with particular attention paid to the poor interphase adhesion between the polymer matrix and a lignocellulosic filler and to the effects of cellulose occurrence in polymorphic varieties. The phenomenon of cellulose polymorphism is very important from the point of view of controlling the nucleation abilities of the lignocellulosic filler and hence the mechanical properties of composites. Macroscopic properties of green composites depend also on the parameters of processing which determine the magnitude and range of shearing forces. The influence of shearing forces appearing upon processing the supermolecular structure of the polymer matrix is also discussed. An important problem from the viewpoint of ecology is the possibility of composite recycling which should be taken into account at the design stage. The methods for recycling of the composites made of thermoplastic polymers filled with renewable lignocellulosic materials are presented and discussed. This paper is a review prepared on the basis of currently available literature which describes the many aspects of the problems related to the possibility of using lignocellulosic components for production of composites with polymers. PMID:28811406

Wear characteristics of polished and glazed lithium disilicate ceramics opposed to three ceramic materials.

PubMed

Saiki, Osamu; Koizumi, Hiroyasu; Akazawa, Nobutaka; Kodaira, Akihisa; Okamura, Kentaro; Matsumura, Hideo

2016-01-01

This study compared the wear characteristics of a heat-pressed lithium disilicate ceramic material opposed to feldspathic porcelain, a lithium disilicate glass ceramic, and zirconia materials. Ceramic plate specimens were prepared from feldspathic porcelain (EX-3 nA1B), lithium disilicate glass ceramics (e.max CAD MO1/C14), and zirconia (Katana KT 10) and then ground or polished. Rounded rod specimens were fabricated from heat-pressed lithium disilicate glass ceramic (e.max press LT A3) and then glazed or polished. A sliding wear testing apparatus was used for wear testing. Wear of glazed rods was greater than that of polished rods when they were abraded with ground zirconia, ground porcelain, polished porcelain, or polished lithium disilicate ceramics. For both glazed and polished rods, wear was greater when the rods were abraded with ground plates. The findings indicate that application of a polished surface rather than a glazed surface is recommended for single restorations made of heat-pressed lithium disilicate material. In addition, care must be taken when polishing opposing materials, especially those used in occlusal contact areas. (J Oral Sci 58, 117-123, 2016).

Effect of filler loading and silane modification on the biodegradability of SBR composites reinforced with peanut shell powder

NASA Astrophysics Data System (ADS)

Shaniba, V.; Balan, Aparna K.; Sreejith, M. P.; Jinitha, T. V.; Subair, N.; Purushothaman, E.

2017-06-01

The development of biocomposites and their applications are important in material science due to environmental and sustainability issues. The extent of degradation depends on the nature of reinforcing filler, particle size and their modification. In this article, we tried to focus on the biodegradation of composites of Styrene Butadiene Rubber (SBR) reinforced with Peanut Shell Powder (PSP) by soil burial test. The composites of SBR with untreated PSP (UPSP) and silane modified PSP (SPSP) of 10 parts per hundred rubber (phr) and 20 phr filler loading in two particle size were buried in the garden soil for six months. The microbial degradation were assessed through the measurement of weight loss, tensile strength and hardness at definite period. The study shows that degradation increases with increase in filler loading and particle size. The chemical treatment of filler has been found to resist the degradation. The analysis of morphological properties by the SEM also confirmed biodegradation process by the microorganism in the soil.

Polymer Nanocomposite Materials with High Dielectric Permittivity and Low Dielectric Loss Properties

NASA Astrophysics Data System (ADS)

Toor, Anju

Materials with high dielectric permittivity have drawn increasing interests in recent years for their important applications in capacitors, actuators, and high energy density pulsed power. Particularly, polymer-based dielectrics are excellent candidates, owing to their properties such as high breakdown strength, low dielectric loss, flexibility and easy processing. To enhance the dielectric permittivity of polymer materials, typically, high dielectric constant filler materials are added to the polymer. Previously, ferroelectric and conductive fillers have been mainly used. However, such systems suffered from various limitations. For example, composites based on ferroelectric materials like barium titanate, exhibited high dielectric loss, and poor saturation voltages. Conductive fillers are used in the form of powder aggregates, and they may show 10-100 times enhancement in dielectric constant, however these nanoparticle aggregates cause the dielectric loss to be significant. Also, agglomerates limit the volume fraction of fillers in polymer and hence, the ability to achieve superior dielectric constants. Thus, the aggregation of nanoparticles is a significant challenge to their use to improve the dielectric permittivity. We propose the use of ligand-coated metal nanoparticle fillers to enhance the dielectric properties of the host polymer while minimizing dielectric loss by preventing nanoparticle agglomeration. The focus is on obtaining uniform dispersion of nanoparticles with no agglomeration by utilizing appropriate ligands/surface functionalizations on the gold nanoparticle surface. Use of ligand coated metal nanoparticles will enhance the dielectric constant while minimizing dielectric loss, even with the particles closely packed in the polymer matrix. Novel combinations of materials, which use 5 nm diameter metal nanoparticles embedded inside high breakdown strength polymer materials are evaluated. High breakdown strength polymer materials are chosen to allow further exploration of these materials for energy storage applications. In summary, two novel nanocomposite materials are designed and synthesized, one involving polyvinylidene fluoride (PVDF) as the host polymer for potential applications in energy storage and the other with SU-8 for microelectronic applications. Scanning elec- tron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy and ultramicrotoming techniques were used for the material characterization of the nanocomposite materials. A homogeneous dispersion of gold nanoparticles with low particle agglomeration has been achieved. Fabricated nanoparticle polymer composite films showed the absence of voids and cracks. Also, no evidence of macro-phase separation of nanoparticles from the polymer phase was observed. This is important because nanoparticle agglomeration and phase separation from the polymer usually results in poor processability of films and a high defect density. Dielectric characterization of the nanocomposite materials showed enhancement in the dielectric constant over the base polymer values and low dielectric loss values were observed.

Simulation of Impact Phenomena on the Composite Structures Containing Ceramic Plates and High Entropy Alloys

NASA Astrophysics Data System (ADS)

Geantă, V.; Cherecheș, T.; Lixandru, P.; Voiculescu, I.; Ștefănoiu, R.; Dragnea, D.; Zecheru, T.; Matache, L.

2017-06-01

Due to excellent mechanical properties, high entropy alloys from the system AlxCrFeCoNi can be used successfully to create composite structures containing both metallic and ceramic plates, which resists at dynamic load during high speeds impact (like projectiles, explosion). The paper presents four different composite structures made from a combination of metallic materials and ceramics plates: duralumin-ceramics, duralumin-ceramics-HEA, HEA-ceramics-HEA, HEA-ceramics-duralumin. Numerical simulation of impact behavior of the composite structures was performed by virtual methods, taking into account the mechanical properties of both materials. The best results were obtained using composite structures HEA-ceramics-HEA, HEA-ceramics-duralumin.

Pressurized heat treatment of glass ceramic

DOEpatents

Kramer, D.P.

1984-04-19

A method of producing a glass-ceramic having a specified thermal expansion value is disclosed. The method includes the step of pressurizing the parent glass material to a predetermined pressure during heat treatment so that the glass-ceramic produced has a specified thermal expansion value. Preferably, the glass-ceramic material is isostatically pressed. A method for forming a strong glass-ceramic to metal seal is also disclosed in which the glass-ceramic is fabricated to have a thermal expansion value equal to that of the metal. The determination of the thermal expansion value of a parent glass material placed in a high-temperature environment is also used to determine the pressure in the environment.

Mixture for producing fracture-resistant, fiber-reinforced ceramic material by microwave heating

DOEpatents

Meek, T.T.; Blake, R.D.

1987-09-22

A fracture-resistant, fiber-reinforced ceramic substrate is produced by a method which involves preparing a ceramic precursor mixture comprising glass material, a coupling agent, and resilient fibers, and then exposing the mixture to microwave energy. The microwave field orients the fibers in the resulting ceramic material in a desired pattern wherein heat later generated in or on the substrate can be dissipated in a desired geometric pattern parallel to the fiber pattern. Additionally, the shunt capacitance of the fracture-resistant, fiber-reinforced ceramic substrate is lower which provides for a quicker transit time for electronic pulses in any conducting pathway etched into the ceramic substrate. 2 figs.

Pressurized heat treatment of glass-ceramic to control thermal expansion

DOEpatents

Kramer, Daniel P.

1985-01-01

A method of producing a glass-ceramic having a specified thermal expansion value is disclosed. The method includes the step of pressurizing the parent glass material to a predetermined pressure during heat treatment so that the glass-ceramic produced has a specified thermal expansion value. Preferably, the glass-ceramic material is isostatically pressed. A method for forming a strong glass-ceramic to metal seal is also disclosed in which the glass-ceramic is fabricated to have a thermal expansion value equal to that of the metal. The determination of the thermal expansion value of a parent glass material placed in a high-temperature environment is also used to determine the pressure in the environment.

Ceramic Technology for Advanced Heat Engines Project. Semiannual progress report, October 1984-March 1985

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

Not Available

1985-09-01

A five-year project plan was developed with extensive input from private industry. The objective of the project is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applicationsmore » in these engines.« less

Ceramic technology for advanced heat engines project: Semiannual progress report for April through September 1986

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

Not Available

1987-03-01

An assessment of needs was completed, and a five-year project plan was developed with extensive input from private industry. Objective is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barriermore » and wear applications in these engines.« less

Hybrid Hydroxyapatite Nanoparticle Colloidal Gels are Injectable Fillers for Bone Tissue Engineering

PubMed Central

Gu, Zhen; Jamal, Syed; Detamore, Michael S.

2013-01-01

Injectable bone fillers have emerged as an alternative to the invasive surgery often required to treat bone defects. Current bone fillers may benefit from improvements in dynamic properties such as shear thinning during injection and recovery of material stiffness after placement. Negatively charged inorganic hydroxyapatite (HAp) nanoparticles (NPs) were assembled with positively charged organic poly(d,l-lactic-co-glycolic acid) (PLGA) NPs to create a cohesive colloidal gel. This material is held together by electrostatic forces that may be disrupted by shear to facilitate extrusion, molding, or injection. Scanning electron micrographs of the dried colloidal gels showed a well-organized, three-dimensional porous structure. Rheology tests revealed that certain colloidal gels could recover after being sheared. Human umbilical cord mesenchymal stem cells were also highly viable when seeded on the colloidal gels. HAp/PLGA NP colloidal gels offer an attractive scheme for injectable filling and regeneration of bone tissue. PMID:23815275

Studies on mechanical properties of graphene based hybrid composites reinforced with kenaf/glass fiber

NASA Astrophysics Data System (ADS)

Kumar, S. C. Ramesh; Shivanand, H. K.; Vidayasagar, H. N.; Nagabhushan, V.

2018-04-01

The polymer composites are developed with natural fibers and fillers as a alternate material for some of the engineering applications in the field of automobiles and domestic purposes are being investigated. The natural fiber composites such as banana, sisal, jute, coir, kenaf and hemp polymer composites appear more effective due to their lightweight, higher specific strength, biodegradable and cost is low. The main objective is to prepare the Kenaf/Glass fiber hybrid composite filled with graphene as nano filler and to investigate the mechanical properties of hybrid composites. The different types of hybrid composites laminates are fabricated without filler, 0.5, 1 & 1.5Wt % of graphene by using kenaf and glass fiber as reinforcing material with epoxy resin. The specimen were prepared as per the ASTM standards and results shows that the mixing of graphene in epoxy resin improves the mechanical properties of hybrid composites.

The characterization of high-density polyethylene/organoclay nanocomposites

NASA Astrophysics Data System (ADS)

Rodrigues, Tathiane Cordeiro; Tavares, Maria Inês Bruno; Soares, Igor Lopes; Moreira, Ana M.

2009-01-01

Polymeric nanocomposites, which are hybrids of polymers and modified inorganic clay with organic surfactants, are extremely attractive in both science and industry. These materials present improvements in such polymer properties as modulus, heat capacity, thermal stability, flame resistance, and so on. Research has been conducted in recent decades to obtain high-quality materials that can be used in applications like food packing, car components, and combustible cells. Polymeric nanocomposites present many advantages in relation to composites due to the quantity of filler added to the polymer and also to the improved properties. In a composite, the quantity of filler must be as high as possible (i.e., over 30%). In the polymeric nanocomposite the quantity of filler varies from 1% to 5% because of the nanosize of the particles. These nanoparticles often have a large surface area that results in improved polymer-matrix properties.

A review on the advances in 3D printing and additive manufacturing of ceramics and ceramic matrix composites for optical applications

NASA Astrophysics Data System (ADS)

Goodman, William A.

2017-09-01

This paper provides a review of advances in 3D printing and additive manufacturing of ceramic and ceramic matrix composites for optical applications. Dr. Goodman has been pioneering additive manufacturing of ceramic matrix composites since 2008. He is the inventor of HoneySiC material, a zero-CTE additively manufactured carbon fiber reinforced silicon carbide ceramic matrix composite, briefly mentioned here. More recently Dr. Goodman has turned his attention to the direct printing of ceramics for optical applications via various techniques including slurry and laser sintering of silicon carbide and other ceramic materials.

Ceramic fiber-reinforced monoclinic celsian phase glass-ceramic matrix composite material

NASA Technical Reports Server (NTRS)

Bansal, Narottam P. (Inventor); Dicarlo, James A. (Inventor)

1994-01-01

A hyridopolysilazane-derived ceramic fiber reinforced monoclinic celsian phase barium aluminum silicate glass-ceramic matrix composite material is prepared by ball-milling an aqueous slurry of BAS glass powder and fine monoclinic celsian seeds. The fibers improve the mechanical strength and fracture toughness and with the matrix provide superior dielectric properties.

Controlled removal of ceramic surfaces with combination of ions implantation and ultrasonic energy

DOEpatents

Boatner, Lynn A.; Rankin, Janet; Thevenard, Paul; Romana, Laurence J.

1995-01-01

A method for tailoring or patterning the surface of ceramic articles is provided by implanting ions to predetermined depth into the ceramic material at a selected surface location with the ions being implanted at a fluence and energy adequate to damage the lattice structure of the ceramic material for bi-axially straining near-surface regions of the ceramic material to the predetermined depth. The resulting metastable near-surface regions of the ceramic material are then contacted with energy pulses from collapsing, ultrasonically-generated cavitation bubbles in a liquid medium for removing to a selected depth the ion-damaged near-surface regions containing the bi-axially strained lattice structure from the ceramic body. Additional patterning of the selected surface location on the ceramic body is provided by implanting a high fluence of high-energy, relatively-light ions at selected surface sites for relaxing the bi-axial strain in the near-surface regions defined by these sites and thereby preventing the removal of such ion-implanted sites by the energy pulses from the collapsing ultrasonic cavitation bubbles.

Modified PZT ceramics as a material that can be used in micromechatronics

NASA Astrophysics Data System (ADS)

Zachariasz, Radosław; Bochenek, Dariusz

2015-11-01

Results on investigations of the PZT type ceramics with the following chemical composition: Pb0.94Sr0.06(Zr0.50 Ti0.50)0.99 Cr0.01O3 (PSZTC) which belongs to a group of multicomponent ceramic materials obtained on basis of the PZT type solid solution, are presented in this work. Ceramics PSZTC was obtained by a free sintering method under the following conditions: Tsint = 1250 °C and tsint = 2 h. Ceramic compacts of specimens for the sintering process were made from the ceramic mass consisting of a mixture of the synthesized PSZTC powder and 3% polyvinyl alcohol while wet. The PSZTC ceramic specimens were subjected to poling by two methods: low temperature and high temperature. On the basis of the examinations made it has been found that the ceramics obtained belongs to ferroelectric-hard materials and that is why it may be used to build resonators, filters and ultrasonic transducers. Contribution to the Topical Issue "Materials for Dielectric Applications" edited by Maciej Jaroszewski and Sabu Thomas.

Particle-filled microporous materials

DOEpatents

McAllister, J.W.; Kinzer, K.E.; Mrozinski, J.S.; Johnson, E.J.; Dyrud, J.F.

1990-09-18

A microporous particulate-filled thermoplastic polymeric article is provided. The article can be in the form of a film, a fiber, or a tube. The article has a thermoplastic polymeric structure having a plurality of interconnected passageways to provide a network of communicating pores. The microporous structure contains discrete submicron or low micron-sized particulate filler, the particulate filler being substantially non-agglomerated. 3 figs.

Facile preparation of nanofiller-paper using mixed office paper without deinking

Treesearch

Qianqian Wang; J.Y. Zhu

2015-01-01

Mixed office paper (MOP) pulp without deinking with an ash content of 18.1 ± 1.5% was used as raw material to produce nanofiller-paper. The MOP pulp with filler was mechanically fibrillated using a laboratory stone grinder. Scanning electron microscope imaging revealed that the ground filler particles were wrapped by cellulose nanofibrils (CNFs), which substantially...

Efficacy of a new filler-containing root coating material for dentin remineralization.

PubMed

Okuyama, Katsushi; Kadowaki, Yoshitaka; Matsuda, Yasuhiro; Hashimoto, Naoki; Oki, Saiko; Yamamoto, Hiroko; Tamaki, Yukimichi; Sano, Hidehiko

2016-08-01

To evaluate a new root coating material containing surface pre-reacted glass-ionomer (S-PRG) filler for remineralization of demineralized dentin. The dentin was exposed on root surfaces of human third molars and demineralized by immersion in demineralization solution for 4 days. The demineralized dentin surface was divided into three areas. The center area was left untreated. The area on one side of the center area was coated with protective wax. The area on the other side was coated with one of four test materials: fluoride-containing S-PRG filler (PRG Barrier Coat: PR), fluoride-containing bonding agent (Bond Force: BF), fluoride-containing glass-ionomer cement as a positive control (Fuji IX EXTRA: EX), or non-fluoride-containing bonding agent as a negative control (Clearfil MegaBond: MB). The samples were stored in remineralization solution for 7 days, and then cut into two slices. The mineral changes, defined as variation in mineral loss between wax-coated area and the central untreated area, were measured in one slice by transversal microradiography. The fluoride concentration was measured in the other slice by µ-particle-induced gamma/X-ray emission. Seven thin specimens (0.25-mm thickness) of each test material were used to determine fluoride ion release from the materials over 21 days. The mineral changes were greatest for EX, followed by PR, with no difference between BF and MB (P> 0.05). Regarding the fluoride concentrations in dentin, there was no difference between EX and PR (P> 0.05). MB had the lowest value (P< 0.01). Fluoride release from EX was largest, followed by PR, with BF showing low fluoride release (P< 0.05). MB had no fluoride release. A new coating material with S-PRG filler can be applied in a thin layer on root dentin, which could be especially useful for hard-to-access lesions. This material remineralized demineralized root dentin and had fluoride diffusion characteristics similar to those of glass-ionomer cement in vitro.

Safety of radiofrequency treatment over human skin previously injected with medium-term injectable soft-tissue augmentation materials: a controlled pilot trial.

PubMed

Alam, Murad; Levy, Ross; Pajvani, Urvi; Pavjani, Urvi; Ramierez, James A; Guitart, Joan; Veen, Heather; Gladstone, Hayes B

2006-03-01

Several soft-tissue augmentation materials are now available for reduction of nasolabial fold creases and perioral rhytides. Nasolabial folds and perioral rhytides can also be improved by skin tightening delivered by non-ablative radiofrequency (RF) treatment. The purpose of this study was to assess the safety of RF treatment over skin areas recently injected with medium-term injectable soft-tissue augmentation materials. Five subjects were assigned to the experimental arm (augmentation materials plus RF) and one to the control arm (augmentation materials alone). Each subject received injections of 0.3 mL of hyaluronic acid derivative (Restylane) and calcium hydroxylapatite (Radiesse) 3 cm apart on the upper inner arm. Two weeks later, two non-overlapping passes of RF (Thermage ThermaCool TC) were delivered at 63.5 setting with medium-fast 1.5 cm2 tip over injected sites in all of the experimental subjects. Punch skin biopsies were obtained 3 days later from each of the two injection sites on each subject. Light microscopy and digital photomicrographs obtained at low, medium, and high power showed no difference between filler materials in experimental and control subjects. In both cases filler was evident at the deep dermal-subcutaneous junction. Nodule formation, foreign body extravasation, or hemorrhage/clot was not observed grossly or histologically. Subjects and physicians did not report any difference in signs and symptoms between the experimental and control arms. Slightly increased transitory pain was noted when RF was delivered over filler versus over normal skin. Applying RF treatment over the same area 2 weeks after deep dermal injection with hyaluronic acid derivatives or calcium hydroxylapatite does not appear to cause gross morphological changes in the filler material or surrounding skin. Further studies with different parameters are necessary to confirm these findings. 2006 Wiley-Liss, Inc.

Thermomechanical properties of zirconium tungstate/hydrogenated nitrile butadiene rubber (HNBR) composites for low-temperature applications

NASA Astrophysics Data System (ADS)

Akulichev, Anton G.; Alcock, Ben; Tiwari, Avinash; Echtermeyer, Andreas T.

2016-12-01

Rubber compounds for pressure sealing application typically have inferior dimensional stability with temperature fluctuations compared with their steel counterparts. This effect may result in seal leakage failures when subjected to decreases in temperature. Composites of hydrogenated nitrile butadiene rubber (HNBR) and zirconium tungstate as a negative thermal expansion filler were prepared in order to control the thermal expansivity of the material. The amount of zirconium tungstate (ZrW2O8) was varied in the range of 0 to about 40 vol%. The coefficient of thermal expansion (CTE), bulk modulus, uniaxial extension and compression set properties were measured. The CTE of the ZrW2O8-filled HNBR decreases with the filler content and it is reduced by a factor of 2 at the highest filler concentration used. The filler effect on CTE is found to be stronger when HNBR is below the glass transition temperature. The experimental thermal expansion data of the composites are compared with the theoretical estimates and predictions given by FEA. The effect of ZrW2O8 on the mechanical characteristics and compression set of these materials is also discussed.

In vivo biofilm formation on different dental ceramics.

PubMed

Bremer, Felicia; Grade, Sebastian; Kohorst, Philipp; Stiesch, Meike

2011-01-01

To investigate the formation of oral biofilm on various dental ceramics in vivo. Five different ceramic materials were included: a veneering glass- ceramic, a lithium disilicate glass-ceramic, a yttrium-stabilized zirconia (Y-TZP), a hot isostatically pressed (HIP) Y-TZP ceramic, and an HIP Y-TZP ceramic with 25% alumina. Test specimens were attached to individually designed acrylic appliances; five volunteers wore these appliances for 24 hours in the maxillary arch. After intraoral exposure, the samples were removed from the appliances and the adhering biofilms vitally stained. Then, the two-dimensional surface coating and thickness of the adhering biofilm were determined by confocal laser scanning microscopy. Statistical analysis was performed using one-way ANOVA with the level of significance set at .05. Significant differences (P < .001) in the bacterial surface coating and in the thickness of the biofilm were found between the various ceramic materials. The lowest surface coating (19.0%) and biofilm thickness (1.9 Μm) were determined on the HIP Y-TZP ceramic; the highest mean values were identified with the lithium disilicate glass-ceramic (46.8%, 12.6 Μm). Biofilm formation on various types of dental ceramics differed significantly; in particular, zirconia exhibited low plaque accumulation. In addition to its high strength, low plaque accumulation makes zirconia a promising material for various indications (including implant abutments and telescopic crowns) that previously were met only with metal-based materials.

Effect of nanofillers' size on surface properties after toothbrush abrasion.

PubMed

Cavalcante, Larissa M; Masouras, Konstantinos; Watts, David C; Pimenta, Luiz A; Silikas, Nick

2009-02-01

To investigate the effect of filler-particle size of experimental and commercial resin composites, undergoing toothbrush abrasion, on three surface properties: surface roughness (SR), surface gloss (G) and color stability (CS). Four model (Ivoclar/Vivadent) and one commercial resin composite (Tokuyama) with varying filler-size from 100-1000 nm were examined. Six discs (10 mm x 2 mm) from each product were prepared and mechanically polished. The samples were then submitted to 20,000 brushing strokes in a toothbrush abrasion machine. SR parameters (Ra, Rt and RSm), G, and CS were measured before and after toothbrush abrasion. Changes in SR and G were analyzed by 2-way ANOVA, with Bonferroni post hoc test. CS values were submitted to one-way ANOVA and Bonferroni post hoc test (alpha=0.05). Initial G values ranged between 73-87 gloss units (GU) and were reduced after toothbrush abrasion to a range of 8-64 GU. Toothbrush abrasion resulted in significant modifications in SR and G amongst the materials tested, attributed to filler sizes. There was statistically significant difference in color (delta E* ranged from 0.38-0.88). Filler size did not affect color stability. Toothbrush abrasion resulted in rougher and matte surfaces for all materials tested. Although the individual differences in surface roughness among filler sizes were not always significant, the correlation showed a trend that larger filler sizes resulted in higher surface roughness after abrasion for the SR parameters Ra and Rt (r = 0.95; r = 0.93, respectively). RSm showed an increase after toothbrush abrasion for all resin composites, however no significant correlation was detected (r = 0.21).There was a significant correlation between G and Ra ratios (r = - 0.95).

Tailoring of physical properties in highly filled experimental nanohybrid resin composites.

PubMed

Pick, Bárbara; Pelka, Matthias; Belli, Renan; Braga, Roberto R; Lohbauer, Ulrich

2011-07-01

To assess the elastic modulus (EM), volumetric shrinkage (VS), and polymerization shrinkage stress (PSS) of experimental highly filled nanohybrid composites as a function of matrix composition, filler distribution, and density. One regular viscosity nanohybrid composite (Grandio, VOCO, Germany) and one flowable nanohybrid composite (Grandio Flow, VOCO) were tested as references along with six highly filled experimental nanohybrid composites (four Bis-GMA-based, one UDMA-based, and one Ormocer®-based). The experimental composites varied in filler size and density. EM values were obtained from the "three-point bending" load-displacement curve. VS was calculated with Archimedes' buoyancy principle. PSS was determined in 1-mm thick specimens placed between two (poly)methyl methacrylate rods (Ø=6mm) attached to an universal testing machine. Data were analyzed using oneway ANOVA, Tukey's test (α=0.05), and linear regression analyses. The flowable composite exhibited the highest VS and PSS but lowest EM. The PSS was significantly lower with Ormocer. The EM was significantly higher among experimental composites with highest filler levels. No significant differences were found between all other experimental composites regarding VS and PSS. Filler density and size did not influence EM, VS, or PSS. Neither the filler configuration nor matrix composition in the investigated materials significantly influenced composite shrinkage and mechanical properties. The highest filled experimental composite seemed to increase EM by keeping VS and PSS low; however, matrix composition seemed to be the determinant factor for shrinkage and stress development. The Ormocer, with reduced PSS, deserves further investigation. Filler size and density did not influence the tested parameters. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

New Manufacturing Method for Paper Filler and Fiber Material

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

Doelle, Klaus

2011-06-26

The use of fillers in printing and writing papers has become a prerequisite for competing in a global market to reduce the cost of materials. Use of calcium carbonates (ranging from 18% to 30%) as filler is a common practice in the paper industry but the choices of fillers for each type of papers vary widely according to its use. The market for uncoated digital printing paper is one that continues to introduce exciting growth projections and it is important to understand the effect that different types of calcium carbonates have on the paper properties made of 100% eucalyptus pulp.more » The current study is focused on selecting the most suitable market available calcium carbonate for the production of uncoated Eucalyptus digital printing paper, targeting a potential filler increase of 5% above the currently used filler content. We made hand sheets using 13 different varieties of widely used calcium carbonates [Nine samples of PCC (two rhombic and seven scalenohedral, covering a wide particle size range from 1.2 {micro}m to 2.9 {micro}m), and four samples of GCC (three anionic and one cationic, with a particle size range from 0.7 {micro}m to 1.5 {micro}m)] available in the market followed by a 12” pilot plant paper machine run. The detailed analysis on the main structural, optical and strength properties of the hand sheets found that the most suitable calcium carbonate for uncoated Eucalyptus digital printing paper production is scalenohedral PCC, with a particle size of 1.9 {micro}m for its positive effects on thickness, stiffness, brightness and opacity of paper.« less

Structure-Composition-Property Relationships in Polymeric Amorphous Calcium Phosphate-Based Dental Composites †

PubMed Central

O’Donnell, Justin N.R.; Schumacher, Gary E.; Antonucci, Joseph M.; Skrtic, Drago

2009-01-01

Our studies of amorphous calcium phosphate (ACP)-based materials over the last decade have yielded bioactive polymeric composites capable of protecting teeth from demineralization or even regenerating lost tooth mineral. The anti-cariogenic/re-mineralizing potential of these ACP composites originates from their propensity, when exposed to the oral environment, to release in a sustained manner sufficient levels of mineral-forming calcium and phosphate ions to promote formation of stable apatitic tooth mineral. However, the less than optimal ACP filler/resin matrix cohesion, excessive polymerization shrinkage and water sorption of these experimental materials can adversely affect their physicochemical and mechanical properties, and, ultimately, limit their lifespan. This study demonstrates the effects of chemical structure and composition of the methacrylate monomers used to form the matrix phase of composites on degree of vinyl conversion (DVC) and water sorption of both copolymers and composites and the release of mineral ions from the composites. Modification of ACP surface via introducing cations and/or polymers ab initio during filler synthesis failed to yield mechanically improved composites. However, moderate improvement in composite’s mechanical stability without compromising its remineralization potential was achieved by silanization and/or milling of ACP filler. Using ethoxylated bisphenol A dimethacrylate or urethane dimethacrylate as base monomers and adding moderate amounts of hydrophilic 2-hydroxyethyl methacrylate or its isomer ethyl-α-hydroxymethacrylate appears to be a promising route to maximize the remineralizing ability of the filler while maintaining high DVC. Exploration of the structure/composition/property relationships of ACP fillers and polymer matrices is complex but essential for achieving a better understanding of the fundamental mechanisms that govern dissolution/re-precipitation of bioactive ACP fillers, and, ultimately, the suitability of the composites for clinical evaluation. PMID:21966588

Electron tomography provides a direct link between the Payne effect and the inter-particle spacing of rubber composites

PubMed Central

Staniewicz, Lech; Vaudey, Thomas; Degrandcourt, Christophe; Couty, Marc; Gaboriaud, Fabien; Midgley, Paul

2014-01-01

Rubber-filler composites are a key component in the manufacture of tyres. The filler provides mechanical reinforcement and additional wear resistance to the rubber, but it in turn introduces non-linear mechanical behaviour to the material which most likely arises from interactions between the filler particles, mediated by the rubber matrix. While various studies have been made on the bulk mechanical properties and of the filler network structure (both imaging and by simulations), there presently does not exist any work directly linking filler particle spacing and mechanical properties. Here we show that using STEM tomography, aided by a machine learning image analysis procedure, to measure silica particle spacings provides a direct link between the inter-particle spacing and the reduction in shear modulus as a function of strain (the Payne effect), measured using dynamic mechanical analysis. Simulations of filler network formation using attractive, repulsive and non-interacting potentials were processed using the same method and compared with the experimental data, with the net result being that an attractive inter-particle potential is the most accurate way of modelling styrene-butadiene rubber-silica composite formation. PMID:25487130

Application and advantages of novel clay ceramic particles (CCPs) in an up-flow anaerobic bio-filter (UAF) for wastewater treatment.

PubMed

Han, Wei; Yue, Qinyan; Wu, Suqing; Zhao, Yaqin; Gao, Baoyu; Li, Qian; Wang, Yan

2013-06-01

Utilization of clay ceramic particles (CCPs) as the novel filter media employed in an up-flow anaerobic bio-filter (UAF) was investigated. After a series of tests and operations, CCPs have presented higher total porosity and roughness, meanwhile lower bulk and grain density. When CCPs were utilized as fillers, the reactor had a shorter start up period of 45 days comparing with conventional reactors, and removal rate of chemical oxygen demand (COD) still reached about 76% at a relatively lower temperature during the stable state. In addition, degradation of COD and ammonia nitrogen (NH4-N) at different media height along the reactor was evaluated, and the dates showed that the main reduction process happened within the first 30 cm media height from the bottom flange. Five phases were observed according to different organic loadings during the experiment period, and the results indicated that COD removal increased linearly when the organic loading was increased. Copyright © 2013 Elsevier Ltd. All rights reserved.

Microwave sintering of ceramic materials

NASA Astrophysics Data System (ADS)

Karayannis, V. G.

2016-11-01

In the present study, the potential of microwave irradiation as an innovative energy- efficient alternative to conventional heating technologies in ceramic manufacturing is reviewed, addressing the advantages/disadvantages, while also commenting on future applications of possible commercial interest. Ceramic materials have been extensively studied and used due to several advantages they exhibit. Sintering ceramics using microwave radiation, a novel technology widely employed in various fields, can be an efficient, economic and environmentally-friendlier approach, to improve the consolidation efficiency and reduce the processing cycle-time, in order to attain substantial energy and cost savings. Microwave sintering provides efficient internal heating, as energy is supplied directly and penetrates the material. Since energy transfer occurs at a molecular level, heat is generated throughout the material, thus avoiding significant temperature gradients between the surface and the interior, which are frequently encountered at high heating rates upon conventional sintering. Thus, rapid, volumetric and uniform heating of various raw materials and secondary resources for ceramic production is possible, with limited grain coarsening, leading to accelerated densification, and uniform and fine-grained microstructures, with enhanced mechanical performance. This is particularly important for manufacturing large-size ceramic products of quality, and also for specialty ceramic materials such as bioceramics and electroceramics. Critical parameters for the process optimization, including the electromagnetic field distribution, microwave-material interaction, heat transfer mechanisms and material transformations, should be taken into consideration.

Strength, fracture toughness and microstructure of a selection of all-ceramic materials. Part I. Pressable and alumina glass-infiltrated ceramics.

PubMed

Guazzato, Massimiliano; Albakry, Mohammad; Ringer, Simon P; Swain, Michael V

2004-06-01

The present study, divided into two parts, aimed to compare the strength, fracture toughness and microstructure of a range of all-ceramic materials. In part I, three hot-pressed glass-ceramics (IPS-Empress, Empress 2 and a new experimental ceramic) and alumina glass-infiltrated ceramics (In-Ceram Alumina), processed by both slip casting and dry pressing, were compared. Tensile strength was appraised on 10 bar-shaped specimens (20 x 4 x 1.2 mm3) for each material with the three-point bending method; the fracture toughness was measured from 20 specimens (20 x 4 x 2 mm3), by using the indentation strength technique. Data were compared with ANOVA and the Sheffé post hoc test (p = 0.05). The volume fraction of each phase, the dimensions and shapes of the grains, porosity and the crack patterns were investigated using SEM. The average and standard deviation in strength (MPa) and fracture toughness (MPa m(1/2)) were: IPS-Empress 106(17)1, 1.2(0.14)1; Empress 2 306(29)2, 2.9(0.51)2, new experimental ceramic 303(49)2, 3.0(0.65)2, In-Ceram Alumina dry-pressed 440(50)2, 3.6(0.26)2, In-Ceram Alumina slip 594(52)3, 4.4(0.48)3. Values with the same superscript number showed no significant statistical difference. Microscopy revealed the relationship between the glass matrix and the crystalline phase and the characteristics of the latter were correlated to the strengthening and toughening mechanisms of these glass-ceramics. The mechanical properties and microstructure of core materials have been advocated as crucial to the clinical long-term performance of all-ceramic dental restorations. This investigation provides the clinician with data regarding strength, fracture toughness and microstructure of a broad range of current materials. Copyright 2003 Academy of Dental Materials

Interdisciplinary research concerning the nature and properties of ceramic materials

NASA Technical Reports Server (NTRS)

1975-01-01

The nature and properties of ceramic materials as they relate to solid state physics and metallurgy are studied. Special attention was given to the applications of ceramics to NASA programs and national needs.

Shear bond strength of brackets on restorative materials: Comparison on various dental restorative materials using the universal primer Monobond® Plus.

PubMed

Ebert, Thomas; Elsner, Laura; Hirschfelder, Ursula; Hanke, Sebastian

2016-03-01

The purpose of this work was to analyze surfaces consisting of different restorative materials for shear bond strength (SBS) and failure patterns of metal and ceramic brackets. Bonding involved the use of a universal primer (Monobond® Plus, Ivoclar Vivadent). Six restorative materials were tested, including one composite resin (Clearfil Majesty™ Posterior, Kuraray Noritake Dental), one glass-ceramic material (IPS Empress® Esthetic, Ivoclar Vivadent), one oxide-ceramic material (CORiTEC Zr transpa Disc, imes-icore), two base-metal alloys (remanium® star, Dentaurum; Colado® CC, Ivoclar Vivadent), and one palladium-based alloy (Callisto® 75 Pd, Ivoclar Vivadent). Bovine incisors served as controls. Both metal and ceramic brackets (discovery®/discovery® pearl; Dentaurum) were bonded to the restorative surfaces after sandblasting and pretreatment with Monobond® Plus. A setup modified from DIN 13990-2 was used for SBS testing and adhesive remnant index (ARI)-based analysis of failure patterns. The metal brackets showed the highest mean SBS values on the glass-ceramic material (68.61 N/mm(2)) and the composite resin (67.58 N/mm(2)) and the lowest mean SBS on one of the base-metal alloys (Colado® CC; 14.01 N/mm(2)). The ceramic brackets showed the highest mean SBS on the glass-ceramic material (63.36 N/mm(2)) and the lowest mean SBS on the palladium-based alloy (38.48 N/mm(2)). Significant differences between the metal and ceramic brackets were observed in terms of both SBS values and ARI scores (p < 0.05). Under both bracket types, fractures of the composite-resin and the glass-ceramic samples were observed upon debonding. Opaque restorative materials under metal brackets were found to involve undercuring of the adhesive. Monobond® Plus succeeded in generating high bond strengths of both bracket types on all restorative surfaces. Given our observations of cohesive fracture (including cases of surface avulsion) of the composite-resin and the glass-ceramic samples, we recommend against using these material combinations in clinical practice.

Friction and wear properties of novel HDPE--HAp--Al2O3 biocomposites against alumina counterface.

PubMed

Bodhak, Subhadip; Nath, Shekhar; Basu, Bikramjit

2009-03-01

In an effort to enhance physical properties of biopolymers (high-density polyethylene, HDPE) in terms of elastic modulus and hardness, various ceramic fillers, like alumina (Al2O3) and hydroxyapatite (HAp) are added, and therefore it is essential to assess the friction and wear resistance properties of HDPE biocomposites. In this perspective, HDPE composites with varying ceramic filler content (upto 40 vol%) were fabricated under the optimal compression molding conditions and their friction and wear properties were evaluated against Al2O3 at fretting contacts. All the experiments were conducted at a load of 10 N for duration of 100,000 cycles in both dry as well as simulated body fluid (SBF). Such planned set of experiments has been designed to address three important issues: (a) whether the improvement in physical properties (hardness, E-modulus) will lead to corresponding improvement in friction and wear properties; (b) whether the fretting in SBF will provide sufficient lubrication in order to considerably enhance the tribological properties, as compared to that in ambient conditions; and (c) whether the generation of wear debris particles be reduced for various compositionally modified polymer composites, in comparison to unreinforced HDPE. The experimental results indicate the possibility of achieving extremely low coefficient of friction (COF approximately 0.047) as well as higher wear resistance (wear rate in the order of approximately 10(-7) mm3 N(-1) m(-1)) with the newly developed composites in SBF. A low wear depth of 3.5-4 microm is recorded, irrespective of fretting environment. Much effort has been put forward to correlate the friction and wear mechanisms with abrasion, adhesion, and wear debris formation.

Composite metal foil and ceramic fabric materials

DOEpatents

Webb, B.J.; Antoniak, Z.I.; Prater, J.T.; DeSteese, J.G.

1992-03-24

The invention comprises new materials useful in a wide variety of terrestrial and space applications. In one aspect, the invention comprises a flexible cloth-like material comprising a layer of flexible woven ceramic fabric bonded with a layer of metallic foil. In another aspect, the invention includes a flexible fluid impermeable barrier comprising a flexible woven ceramic fabric layer having metal wire woven therein. A metallic foil layer is incontinuously welded to the woven metal wire. In yet another aspect, the invention includes a material comprising a layer of flexible woven ceramic fabric bonded with a layer of an organic polymer. In still another aspect, the invention includes a rigid fabric structure comprising a flexible woven ceramic fabric and a resinous support material which has been hardened as the direct result of exposure to ultraviolet light. Inventive methods for producing such material are also disclosed. 11 figs.

Interdisciplinary research and development on the effects of the nature and properties of ceramic materials in the design of advanced structural components

NASA Technical Reports Server (NTRS)

1978-01-01

An educational development and supportive research program on ceramic materials established to advance design methodology, improve materials, and develop engineers knowledgable in design with and use of high performance ceramic materials is described. Emphasis is on the structures and related materials problems in a ceramic turbine engine, but applications in coal gasification, solar conversion, and magnetohydrodynamic technologies are considered. Progress of various research projects in the areas of new materials, processing, characterization, and nondestructive testing is reported. Fracture toughness determination, extended X-ray absorption fine structure measurements, and grain boundary effects in beta-alumina are among the topics covered.

Novel Attrition-Resistant Fischer Tropsch Catalyst

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

Weast, Logan, E.; Staats, William, R.

2009-05-01

There is a strong national interest in the Fischer-Tropsch synthesis process because it offers the possibility of making liquid hydrocarbon fuels from reformed natural gas or coal and biomass gasification products. This project explored a new approach that had been developed to produce active, attrition-resistant Fischer-Tropsch catalysts that are based on glass-ceramic materials and technology. This novel approach represented a promising solution to the problem of reducing or eliminating catalyst attrition and maximizing catalytic activity, thus reducing costs. The technical objective of the Phase I work was to demonstrate that glass-ceramic based catalytic materials for Fischer-Tropsch synthesis have resistance tomore » catalytic deactivation and reduction of particle size superior to traditional supported Fischer-Tropsch catalyst materials. Additionally, these novel glass-ceramic-based materials were expected to exhibit catalytic activity similar to the traditional materials. If successfully developed, the attrition-resistant Fischer-Tropsch catalyst materials would be expected to result in significant technical, economic, and social benefits for both producers and public consumers of Fischer-Tropsch products such as liquid fuels from coal or biomass gasification. This program demonstrated the anticipated high attrition resistance of the glass-ceramic materials. However, the observed catalytic activity of the materials was not sufficient to justify further development at this time. Additional testing documented that a lack of pore volume in the glass-ceramic materials limited the amount of surface area available for catalysis and consequently limited catalytic activity. However, previous work on glass-ceramic catalysts to promote other reactions demonstrated that commercial levels of activity can be achieved, at least for those reactions. Therefore, we recommend that glass-ceramic materials be considered again as potential Fischer-Tropsch catalysts if it can be demonstrated that materials with adequate pore volume can be produced. During the attrition resistance tests, it was learned that the glass-ceramic materials are very abrasive. Attention should be paid in any further developmental efforts to the potential for these hard, abrasive materials to damage reactors.« less

Ceramic Processing

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

EWSUK,KEVIN G.

1999-11-24

Ceramics represent a unique class of materials that are distinguished from common metals and plastics by their: (1) high hardness, stiffness, and good wear properties (i.e., abrasion resistance); (2) ability to withstand high temperatures (i.e., refractoriness); (3) chemical durability; and (4) electrical properties that allow them to be electrical insulators, semiconductors, or ionic conductors. Ceramics can be broken down into two general categories, traditional and advanced ceramics. Traditional ceramics include common household products such as clay pots, tiles, pipe, and bricks, porcelain china, sinks, and electrical insulators, and thermally insulating refractory bricks for ovens and fireplaces. Advanced ceramics, also referredmore » to as ''high-tech'' ceramics, include products such as spark plug bodies, piston rings, catalyst supports, and water pump seals for automobiles, thermally insulating tiles for the space shuttle, sodium vapor lamp tubes in streetlights, and the capacitors, resistors, transducers, and varistors in the solid-state electronics we use daily. The major differences between traditional and advanced ceramics are in the processing tolerances and cost. Traditional ceramics are manufactured with inexpensive raw materials, are relatively tolerant of minor process deviations, and are relatively inexpensive. Advanced ceramics are typically made with more refined raw materials and processing to optimize a given property or combination of properties (e.g., mechanical, electrical, dielectric, optical, thermal, physical, and/or magnetic) for a given application. Advanced ceramics generally have improved performance and reliability over traditional ceramics, but are typically more expensive. Additionally, advanced ceramics are typically more sensitive to the chemical and physical defects present in the starting raw materials, or those that are introduced during manufacturing.« less

Corundum ceramic materials modified with silica nanopowders: structure and mechanical properties

NASA Astrophysics Data System (ADS)

Kostytsyn, M. A.; Muratov, D. S.; Lysov, D. V.; Chuprunov, K. O.; Yudin, A. G.; Leybo, D. V.

2016-01-01

Filtering elements are often used in the metallurgy of rare earth metals. Corundum ceramic is one of the most suitable materials for this purpose. The process of formation and the properties of nanomodified ceramic materials, which are proposed as filtering materials with tunable effective porosity, are described. A silica nanopowder is used as a porosity-increasing agent. Vortex layer apparatus is used for mixing of precursor materials. The obtained results show that nanomodification with the vortex layer apparatus using 0.04 wt. % silica nanopowder as a modifying agent leads to an increase in the compression strength of corundum ceramic by the factor of 1.5.

Supramolecular Polymer Nanocomposites - Improvement of Mechanical Properties

NASA Astrophysics Data System (ADS)

Hinricher, Jesse; Neikirk, Colin; Priestley, Rodney

2015-03-01

Supramolecular polymers differ from traditional polymers in that their repeat units are connected by hydrogen bonds that can reversibly break and form under various stimuli. They can be more easily recycled than conventional materials, and their highly temperature dependent viscosities result in reduced energy consumption and processing costs. Furthermore, judicious selection of supramolecular polymer architecture and functionality allows the design of advanced materials including shape memory and self-healing materials. Supramolecular polymers have yet to see widespread use because they can't support much weight due to their inherent mechanical weakness. In order to address this issue, the mechanical strength of supramolecular polymer nanocomposites based on ureidopyrmidinone (UPy) telechelic poly(caprolactone) doped with surface activated silica nanoparticles was investigated by tensile testing and dynamic mechanical analysis. The effects of varying amounts and types of nanofiller surface functionality were investigated to glean insight into the contributions of filler-filler and filler-matrix interactions to mechanical reinforcement in supramolecular polymer nanocomposites. MRSEC NSF DMR 0819860 (PI: Prof. N. Phuan Ong) REU Site Grant: NSF DMR-1156422 (PI: Prof. Mikko Haataja)

The application of silicon sol-gel technology to forensic blood substitute development: Mimicking aspects of whole human blood rheology.

PubMed

Stotesbury, Theresa; Illes, Mike; Wilson, Paul; Vreugdenhil, Andrew J

2017-01-01

Solution-gelation chemistry has promising applications in forensic synthetic blood substitute development. This research offers a silicon-based sol-gel approach to creating stable materials that share similar rheological properties to that of whole human blood samples. Room temperature, high water content, silicon sol-gels were created using the organosilane precursors 3-glycidoxypropyltrimethoxysilane and tetraethylorthosilicate along with various concentrations of filler and pigment. Shear-thinning non-Newtonian properties were observed within most formulations of the presented materials. The effects of colloidal concentration, temperature, age and filler addition on the viscosity of the sol-gels were investigated. SEM-EDS analysis was used to identify the behavior of the fillers within the film and support their inclusion for basic bloodstain pattern simulation. A final proposed candidate sol-gel was assessed using a previously reported passive drip simulation test on a hard, dry surface and passed. This works represents encouraging development in providing safe material alternatives to using whole human blood for forensic training and research. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Liquid crystalline epoxy nanocomposite material for dental application.

PubMed

Tai, Yun-Yuan; Hsu, Sheng-Hao; Chen, Rung-Shu; Su, Wei-Fang; Chen, Min-Huey

2015-01-01

Novel liquid crystalline epoxy nanocomposites, which exhibit reduced polymerization shrinkage and effectively bond to tooth structures, can be applied in esthetic dentistry, including core and post systems, direct and indirect restorations, and dental brackets. The purposes of this study were to investigate the properties of liquid crystalline epoxy nanocomposites including biocompatibility, microhardness, and frictional forces of bracket-like blocks with different filler contents for further clinical applications. In this study, we evaluated liquid crystalline epoxy nanocomposite materials that exhibited various filler contents, by assessing their cell activity performance using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and their microhardness with or without thermocycling. We also evaluated the frictional force between bracket-like duplicates and commercially available esthetic bracket systems using Instron 5566. The liquid crystalline epoxy nanocomposite materials showed good biocompatibility. The materials having high filler content demonstrated greater microhardness compared with commercially available bracket materials, before and after the thermocycling treatment. Thus, manufacturing processes are important to reduce frictional force experienced by orthodontic brackets. The microhardness of the bracket-like blocks made by our new material is superior to the commercially available brackets, even after thermocycling. Our results indicate that the evaluated liquid crystalline epoxy nanocomposite materials are of an appropriate quality for application in dental core and post systems and in various restorations. By applying technology to refine manufacturing processes, these new materials could also be used to fabricate esthetic brackets for orthodontic treatment. Copyright © 2014. Published by Elsevier B.V.

NASA Glenn Research Center UEET (Ultra-Efficient Engine Technology) Program: Agenda and Abstracts

NASA Technical Reports Server (NTRS)

Manthey, Lri

2001-01-01

Topics discussed include: UEET Overview; Technology Benefits; Emissions Overview; P&W Low Emissions Combustor Development; GE Low Emissions Combustor Development; Rolls-Royce Low Emissions Combustor Development; Honeywell Low Emissions Combustor Development; NASA Multipoint LDI Development; Stanford Activities In Concepts for Advanced Gas Turbine Combustors; Large Eddy Simulation (LES) of Gas Turbine Combustion; NASA National Combustion Code Simulations; Materials Overview; Thermal Barrier Coatings for Airfoil Applications; Disk Alloy Development; Turbine Blade Alloy; Ceramic Matrix Composite (CMC) Materials Development; Ceramic Matrix Composite (CMC) Materials Characterization; Environmental Barrier Coatings (EBC) for Ceramic Matrix Composite (CMC) Materials; Ceramic Matrix Composite Vane Rig Testing and Design; Ultra-High Temperature Ceramic (UHTC) Development; Lightweight Structures; NPARC Alliance; Technology Transfer and Commercialization; and Turbomachinery Overview; etc.

Process for making a ceramic composition for immobilization of actinides

DOEpatents

Ebbinghaus, Bartley B.; Van Konynenburg, Richard A.; Vance, Eric R.; Stewart, Martin W.; Walls, Philip A.; Brummond, William Allen; Armantrout, Guy A.; Herman, Connie Cicero; Hobson, Beverly F.; Herman, David Thomas; Curtis, Paul G.; Farmer, Joseph

2001-01-01

Disclosed is a process for making a ceramic composition for the immobilization of actinides, particularly uranium and plutonium. The ceramic is a titanate material comprising pyrochlore, brannerite and rutile. The process comprises oxidizing the actinides, milling the oxides to a powder, blending them with ceramic precursors, cold pressing the blend and sintering the pressed material.

Development of Brazing Technology for Use in High- Temperature Gas Separation Equipment

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

Weil, K.S.; Hardy, J.S.; Kim, J.Y.

2003-04-23

The development of high-temperature electrochemical devices such as oxygen and hydrogen separators, fuel gas reformers, solid oxide fuel cells, and chemical sensors is part of a rapidly expanding segment of the solid state technology market. These devices employ an ionic conducting ceramic as the active membrane that establishes the electrochemical potential of the device, either under voltage (i.e. to carry out gas separation) or under chemical gradient (to develop an electrical potential and thereby generate electrical power). Because the device operates under an ionic gradient that develops across the electrolyte, hermiticity across this layer is paramount. That is, not onlymore » must this thin ceramic membrane be dense with no interconnected porosity, but it must be connected to the rest of the device, typically constructed from a heat resistant alloy, with a high-temperature, gas-tight seal. A significant engineering challenge in fabricating these devices is how to effectively join the thin electrochemically active membrane to the metallic body of the device such that the resulting seal is hermetic, rugged, and stable during continuous high temperature operation. Active metal brazing is the typical method of joining ceramic and metal engineering components. It employs a braze alloy that contains one or more reactive elements, often titanium, which will chemically reduce the ceramic faying surface and greatly improve its wetting behavior and adherence with the braze. However, recent studies of these brazes for potential use in fabricating high-temperature electrochemical devices revealed problems with interfacial oxidation and subsequent joint failure [1,2]. Specifically, it was found that the introduction of the ceramic electrolyte and/or heat resistant metal substrate dramatically affects the inherent oxidation behavior of the braze, often in a deleterious manner. These conclusions pointed to the need for an oxidation resistant, high-temperature ceramic-to-metal braze and consequently lead to the development of the novel reactive air brazing (RAB) concept. The goal in RAB is to reactively modify one or both oxide faying surfaces with an oxide compound dissolved in a molten noble metal alloy such that the newly formed surface is readily wetted by the remaining liquid filler material. In many respects, this concept is similar to active metal brazing, except that joining can be conducted in air and the final joint will be resistant to oxidation at high temperature. Potentially, there are a number of metal oxide-noble metal systems that can be considered for RAB, including Ag-CuO, Ag-V2O5, and Pt-Nb2O5. Our current interest is in determining whether the Ag-CuO system is suitable for air brazing functional ceramic-to-metal joints such as those needed in practical electrochemical devices. In a series of studies, the wetting behavior of the Ag-CuO braze was investigated with respect to a number of potential hydrogen separation, oxygen separation, and fuel cell electrolyte membrane materials and heat resistant metal systems, including: alumina, (La0.6Sr0.4)(Co0.2Fe0.8)O3, (La0.8Sr0.2)FeO3, YSZ, fecralloy, and Crofer-22APU. Selected findings from these studies as well as from our work on joint strength and durability during high-temperature exposure testing will be discussed.« less

Ceramic heat exchanger

DOEpatents

LaHaye, Paul G.; Rahman, Faress H.; Lebeau, Thomas P. E.; Severin, Barbara K.

1998-01-01

A tube containment system. The tube containment system does not significantly reduce heat transfer through the tube wall. The contained tube is internally pressurized, and is formed from a ceramic material having high strength, high thermal conductivity, and good thermal shock resistance. The tube containment system includes at least one ceramic fiber braid material disposed about the internally pressurized tube. The material is disposed about the tube in a predetermined axial spacing arrangement. The ceramic fiber braid is present in an amount sufficient to contain the tube if the tube becomes fractured. The tube containment system can also include a plurality of ceramic ring-shaped structures, in contact with the outer surface of the tube, and positioned between the tube and the ceramic fiber braid material, and/or at least one transducer positioned within tube for reducing the internal volume and, therefore, the energy of any shrapnel resulting from a tube fracture.

Ceramic heat exchanger

DOEpatents

LaHaye, P.G.; Rahman, F.H.; Lebeau, T.P.; Severin, B.K.

1998-06-16

A tube containment system is disclosed. The tube containment system does not significantly reduce heat transfer through the tube wall. The contained tube is internally pressurized, and is formed from a ceramic material having high strength, high thermal conductivity, and good thermal shock resistance. The tube containment system includes at least one ceramic fiber braid material disposed about the internally pressurized tube. The material is disposed about the tube in a predetermined axial spacing arrangement. The ceramic fiber braid is present in an amount sufficient to contain the tube if the tube becomes fractured. The tube containment system can also include a plurality of ceramic ring-shaped structures, in contact with the outer surface of the tube, and positioned between the tube and the ceramic fiber braid material, and/or at least one transducer positioned within tube for reducing the internal volume and, therefore, the energy of any shrapnel resulting from a tube fracture. 6 figs.

Protective coating for ceramic materials

NASA Technical Reports Server (NTRS)

Kourtides, Demetrius A. (Inventor); Churchward, Rex A. (Inventor); Lowe, David M. (Inventor)

1994-01-01

A protective coating for ceramic materials such as those made of silicon carbide, aluminum oxide, zirconium oxide, aluminoborosilicate and silicon dioxide, and a thermal control structure comprising a ceramic material having coated thereon the protective coating. The protective coating contains, in admixture, silicon dioxide powder, colloidal silicon dioxide, water, and one or more emittance agents selected from silicon tetraboride, silicon hexaboride, silicon carbide, molybdenum disilicide, tungsten disilicide and zirconium diboride. In another aspect, the protective coating is coated on a flexible ceramic fabric which is the outer cover of a composite insulation. In yet another aspect, a metallic foil is bonded to the outer surface of a ceramic fabric outer cover of a composite insulation via the protective coating. A primary application of this invention is as a protective coating for ceramic materials used in a heat shield for space vehicles subjected to very high aero-convective heating environments.

High-Temperature Active Soldering of SiC Particle-Reinforced Al-MMC Using a Novel ZnAlGaMgTi Filler Metal

NASA Astrophysics Data System (ADS)

Chen, Biqiang; Zhang, Guifeng; Zhang, Linjie; Xu, Tingting

2017-10-01

In order to broaden the application of SiC particle-reinforced aluminum matrix composite in electronics packaging, newly developed ZnAlGaMgTi filler with a low melting point of 418-441 °C was utilized as filler metal for active soldering of aluminum matrix composites (70 vol.%, SiCp/Al-MMCs) for the first time. The effect of loading pressure on joint properties of ZnAlGaMgTi active filler was investigated. The experimental results indicated that novel filler could successfully solder Al-MMCs, and the presence of Mg in the filler enhanced the penetration of Zn, while the forming of Zn-rich barrier layer influenced the active element MPD (melting point depressant) diffusion into parent composite, and the bulk-like (Mg-Si)-rich phase and Ti-containing phase were readily observed at the interface and bond seam. With the increase in loading pressure, the runout phenomenon appeared more significant, and the filler foil thickness and the Zn penetration depth varied pronouncedly. Sound joints with maximum shear strength of 29.6 MPa were produced at 480 °C at 1 MPa, and the crack occurred adjacent to the boundary of SiC particle and then propagated along the interface. A novel model describing the significant mutual diffusion of Al and Zn atoms between the parent material and solder was proposed.

A Viscoplastic Constitutive Theory for Monolithic Ceramic Materials. Series 1

NASA Technical Reports Server (NTRS)

Janosik, Lesley A.; Duffy, Stephen F.

1997-01-01

With increasing use of ceramic materials in high temperature structural applications such as advanced heat engine components, the need arises to accurately predict thermomechanical behavior. This paper, which is the first of two in a series, will focus on inelastic deformation behavior associated with these service conditions by providing an overview of a viscoplastic constitutive model that accounts for time-dependent hereditary material deformation (e.g., creep, stress relaxation, etc.) in monolithic structural ceramics. Early work in the field of metal plasticity indicated that inelastic deformations are essentially unaffected by hydrostatic stress. This is not the case, however, for ceramic-based material systems, unless the ceramic is fully dense. The theory presented here allows for fully dense material behavior as a limiting case. In addition, ceramic materials exhibit different time-dependent behavior in tension and compression. Thus, inelastic deformation models for ceramics must be constructed in a fashion that admits both sensitivity to hydrostatic stress and differing behavior in tension and compression. A number of constitutive theories for materials that exhibit sensitivity to the hydrostatic component of stress have been proposed that characterize deformation using time-independent classical plasticity as a foundation. However, none of these theories allow different behavior in tension and compression. In addition, these theories are somewhat lacking in that they are unable to capture creep, relaxation, and rate-sensitive phenomena exhibited by ceramic materials at high temperature. When subjected to elevated service temperatures, ceramic materials exhibit complex thermomechanical behavior that is inherently time-dependent, and hereditary in the sense that current behavior depends not only on current conditions, but also on thermo-mechanical history. The objective of this work is to present the formulation of a macroscopic continuum theory that captures these time-dependent phenomena. Specifically, the overview contained in this paper focuses on the multiaxial derivation of the constitutive model, and examines the scalar threshold function and its attending geometrical implications.

Porous ceramic scaffolds with complex architectures

NASA Astrophysics Data System (ADS)

Munch, E.; Franco, J.; Deville, S.; Hunger, P.; Saiz, E.; Tomsia, A. P.

2008-06-01

This work compares two novel techniques for the fabrication of ceramic scaffolds for bone tissue engineering with complex porosity: robocasting and freeze casting. Both techniques are based on the preparation of concentrated ceramic suspensions with suitable properties for the process. In robocasting, the computer-guided deposition of the suspensions is used to build porous materials with designed three dimensional geometries and microstructures. Freeze casting uses ice crystals as a template to form porous lamellar ceramic materials. Preliminary results on the compressive strengths of the materials are also reported.

Advanced Ceramics for NASA's Current and Future Needs

NASA Technical Reports Server (NTRS)

Jaskowiak, Martha H.

2006-01-01

Ceramic composites and monolithics are widely recognized by NASA as enabling materials for a variety of aerospace applications. Compared to traditional materials, ceramic materials offer higher specific strength which can enable lighter weight vehicle and engine concepts, increased payloads, and increased operational margins. Additionally, the higher temperature capabilities of these materials allows for increased operating temperatures within the engine and on the vehicle surfaces which can lead to improved engine efficiency and vehicle performance. To meet the requirements of the next generation of both rocket and air-breathing engines, NASA is actively pursuing the development and maturation of a variety of ceramic materials. Anticipated applications for carbide, nitride and oxide-based ceramics will be presented. The current status of these materials and needs for future goals will be outlined. NASA also understands the importance of teaming with other government agencies and industry to optimize these materials and advance them to the level of maturation needed for eventual vehicle and engine demonstrations. A number of successful partnering efforts with NASA and industry will be highlighted.

Natural radionuclides in ceramic building materials available in Cuddalore district, Tamil Nadu, India.

PubMed

Rajamannan, B; Viruthagiri, G; Suresh Jawahar, K

2013-10-01

The activity concentrations of radium, thorium and potassium can vary from material to material and they should be measured as the radiation is hazardous for human health. Thus, studies have been planned to obtain the radioactivity of ceramic building materials used in Cuddalore District, Tamilnadu, India. The radioactivity of some ceramic materials used in this region has been measured using a gamma-ray spectrometry, which contains an NaI(Tl) detector connected to multichannel analyzer. The specific activities of (226)Ra, (232)Th and (40)K, from the selected ceramic building materials, were in the range of 9.89-30.75, 24.68-70.4, 117.19-415.83 Bq kg(-1), respectively. The radium equivalent activity, absorbed gamma dose rate (D) and annual effective dose rate associated with the natural radionuclides are calculated to assess the radiation hazards of the natural radioactivity in the ceramic building materials. It was found that none of the results exceeds the recommended limit value.

Laser Surface Treatment of Sintered Alumina

NASA Astrophysics Data System (ADS)

Hagemann, R.; Noelke, C.; Kaierle, S.; Wesling, V.

Sintered alumina ceramics are used as refractory materials for industrial aluminum furnaces. In this environment the ceramic surface is in permanent contact with molten aluminum resulting in deposition of oxidic material on its surface. Consequently, a lower volume capacity as well as thermal efficiency of the furnaces follows. To reduce oxidic adherence of the ceramic material, two laser-based surface treatment processes were investigated: a powder- based single-step laser cladding and a laser surface remelting. Main objective is to achieve an improved surface quality of the ceramic material considering the industrial requirements as a high process speed.

Trends of microwave dielectric materials for antenna application

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

Sulong, T. A. T., E-mail: tuanamirahtuansulong@gmail.com; Osman, R. A. M., E-mail: rozana@unimap.edu.my; Idris, M. S., E-mail: sobri@unimap.edu.my

Rapid development of a modern microwave communication system requires a high quality microwave dielectric ceramic material to be used as mobile and satellite communication. High permittivity of dielectric ceramics leads to fabrication of compact device for electronic components. Dielectric ceramics which used for microwave applications required three important parameters such as high or appropriate permittivity (ε{sub r}), high quality factor (Q {sub f} ≥ 5000 GH z) and good temperature coefficient of resonant frequency (τ{sub f}). This paper review of various dielectric ceramic materials used as microwave dielectric materials and related parameters for antenna applications.

The precursors effects on biomimetic hydroxyapatite ceramic powders.

PubMed

Yoruç, Afife Binnaz Hazar; Aydınoğlu, Aysu

2017-06-01

In this study, effects of the starting material on chemical, physical, and biological properties of biomimetic hydroxyapatite ceramic powders (BHA) were investigated. Characterization and chemical analysis of BHA powders were performed by using XRD, FT-IR, and ICP-AES. Microstructural features such as size and morphology of the resulting BHA powders were characterized by using BET, nano particle sizer, pycnometer, and SEM. Additionally, biological properties of the BHA ceramic powders were also investigated by using water-soluble tetrazolium salts test (WST-1). According to the chemical analysis of BHA ceramic powders, chemical structures of ceramics which are prepared under different conditions and by using different starting materials show differences. Ceramic powders which are produced at 80°C are mainly composed of hydroxyapatite, dental hydroxyapatite (contain Na and Mg elements in addition to Ca), and calcium phosphate sulfide. However, these structures are altered at high temperatures such as 900°C depending on the features of starting materials and form various calcium phosphate ceramics and/or their mixtures such as Na-Mg-hydroxyapatite, hydroxyapatite, Mg-Whitlockit, and chloroapatite. In vitro cytotoxicity studies showed that amorphous ceramics produced at 80°C and ceramics containing chloroapatite structure as main or secondary phases were found to be extremely cytotoxic. Furthermore, cell culture studies showed that highly crystalline pure hydroxyapatite structures were extremely cytotoxic due to their high crystallinity values. Consequently, the current study indicates that the selection of starting materials which can be used in the production of calcium phosphate ceramics is very important. It is possible to produce calcium phosphate ceramics which have sufficient biocompatibility at physiological pH values and by using appropriate starting materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Biaxial flexural strength of Turkom-Cera core compared to two other all-ceramic systems.

PubMed

Al-Makramani, Bandar Mohammed Abdullah; Razak, Abdul Aziz Abdul; Abu-Hassan, Mohamed Ibrahim

2010-12-01

Advances in all-ceramic systems have established predictable means of providing metal-free aesthetic and biocompatible materials. These materials must have sufficient strength to be a practical treatment alternative for the fabrication of crowns and fixed partial dentures. The aim of this study was to compare the biaxial flexural strength of three core ceramic materials. Three groups of 10 disc-shaped specimens (16 mm diameter x 1.2 mm thickness - in accordance with ISO-6872, 1995) were made from the following ceramic materials: Turkom-Cera Fused Alumina [(Turkom-Ceramic (M) Sdn Bhd, Puchong, Selangor, Malaysia)], In-Ceram (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany) and Vitadur-N (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany), which were sintered according to the manufacturer's recommendations. The specimens were subjected to biaxial flexural strength test in an universal testing machine at a crosshead speed of 0.5 mm/min. The definitive fracture load was recorded for each specimen and the biaxial flexural strength was calculated from an equation in accordance with ISO-6872. The mean biaxial flexural strength values were: Turkom-Cera: 506.8 ± 87.01 MPa, In-Ceram: 347.4 ± 28.83 MPa and Vitadur-N: 128.7 ± 12.72 MPa. The results were analyzed by the Levene's test and Dunnett's T3 post-hoc test (SPSS software V11.5.0 for Windows, SPSS, Chicago, IL, USA ) at a preset significance level of 5% because of unequal group variances (P<0.001). There was statistically significant difference between the three core ceramics (P<0.05). Turkom-Cera showed the highest biaxial flexural strength, followed by In-Ceram and Vitadur-N. Turkom-Cera core had significantly higher flexural strength than In-Ceram and Vitadur-N ceramic core materials.

Method of manufacturing ceramic shaped articles

NASA Technical Reports Server (NTRS)

Inoue, K.

1983-01-01

A method of manufacturing ceramic shaped articles, wherein tapes of ceramic powder material in mixture with a binder material and special additives are shaped and then articles are stamped out from said tapes and sintered in a sintering furnace is described.

Shrinkage-stress kinetics of photopolymerised resin-composites

NASA Astrophysics Data System (ADS)

Satterthwaite, Julian D.

The use of directly-placed substances as restorative materials in teeth remains the technique of choice for preserving function and form in teeth that have cavities. The current aesthetic restorative materials of choice are resin-composite materials, although these undergo molecular densification during polymerisation, which has deleterious effects. Although shrinkage-strain is the cause, it is the shrinkage-stress effects that may be seen as being responsible for the problems with adhesive resin-based restorations that are encountered clinically, the bond may fail with separation of the material from the cavity wall, leading to marginal discolouration, pulpal irritation and subsequent necrosis, post operative sensitivity, recurrent caries and eventual failure of restorations. Other outcomes include cohesive fracture of enamel or cusps, cuspal movement (strain) and persistent pain. The aims of this research were to characterise the effects of variations in resin-composite formulation on shrinkage-strain and shrinkage-stress kinetics. In particular, the influence of the size and morphology of the dispersed phase was investigated through the study of experimental formulations. Polymerisation shrinkage-strain kinetics were assessed with the bonded-disk method. It was found that resin-composites with spherical filler particles had significantly lower shrinkage-strain compared to those with irregular filler particles. Additionally, shrinkage-strain was found to be dependent on the size of filler particle, and this trend was related, in part, to differences in the degree of conversion. The data were also used to calculate the activation energy for each material, and a relationship between this and filler particle size for the irregular fillers was demonstrated. A fixed-compliance cantilever beam instrument (Bioman) was used for characterisation of shrinkage-stress kinetics. Significant differences were identified between materials in relation to filler particle size and morphology. A hypothesis for these interactions, relating to surface area effects, was presented. The complex interactions leading to the development of shrinkage-stress were investigated further. Shrinkage-stress over a 24 hour period was assessed, and modelled through application of the Kohlrausch-Williams-Watts equation. The effect of variation in specimen dimensions were assessed, and it was shown that the relationship of the specimen height and diameter to shrinkage-stress is a function not only of the C-factor (the ratio of bonded to unbonded surfaces), but also how the C-factor is created. These relationships were characterised and descriptive equations fitted to the data to describe the phenomena. Shrinkage-stress measurements against a variety of test surfaces were also assessed, and the use of stainless steel as a test surface was validated. Finally, exploratory research was undertaken to develop a moire interferometer for the measurement of in-plane displacements and strain arising in teeth due to polymerisation of resin-composite restorations.

Acoustic Identification of Filler Materials in Unexploded Ordnance

DTIC Science & Technology

2006-04-01

PBXN- 103 CH-6 PBXW- 108 Parrafin ( wax ) Baratol (76/24) Plaster TNT Octol (50/50) Comp B PETN Concrete Lo ng itu di na l V el oc ity (m /s ec...26 3.7.3 Identification of Wax fillers...plaster and wax from “other” items including explosives. A series of field tests are described that focus on acoustic measurements on both inert and live

In vitro Fracture strength and hardness of different computer-aided design/computer-aided manufacturing inlays.

PubMed

Sagsoz, O; Yildiz, M; Hojjat Ghahramanzadeh, A S L; Alsaran, A

2018-03-01

The purpose of this study was to examine the fracture strength and surface microhardness of computer-aided design/computer-aided manufacturing (CAD/CAM) materials in vitro. Mesial-occlusal-distal inlays were made from five different CAD/CAM materials (feldspathic ceramic, CEREC blocs; leucite-reinforced ceramic, IPS Empress CAD; resin nano ceramic, 3M ESPE Lava Ultimate; hybrid ceramic, VITA Enamic; and lithium disilicate ceramic, IPS e.max CAD) using CEREC 4 CAD/CAM system. Samples were adhesively cemented to metal analogs with a resin cement (3M ESPE, U200). The fracture tests were carried out with a universal testing machine. Furthermore, five samples were prepared from each CAD/CAM material for micro-Vickers hardness test. Data were analyzed with statistics software SPSS 20 (IBM Corp., New York, USA). Fracture strength of lithium disilicate inlays (3949 N) was found to be higher than other ceramic inlays (P < 0.05). There was no difference between other inlays statistically (P > 0.05). The highest micro-Vickers hardness was measured in lithium disilicate samples, and the lowest was in resin nano ceramic samples. Fracture strength results demonstrate that inlays can withstand the forces in the mouth. Statistical results showed that fracture strength and micro-Vickers hardness of feldspathic ceramic, leucite-reinforced ceramic, and lithium disilicate ceramic materials had a positive correlation.

Thermoplastic rubberlike material produced at low cost

NASA Technical Reports Server (NTRS)

Hendel, F. J.

1966-01-01

Thermoplastic rubberlike material is prepared by blending a copolymer of ethylene and vinyl acetate with asphalt and a petroleum distillate. This low cost material is easily molded or extruded and is compatible with a variety of fillers.

Feasibility of using microencapsulated phase change materials as filler for improving low temperature performance of rubber sealing materials.

PubMed

Tiwari, Avinash; Shubin, Sergey N; Alcock, Ben; Freidin, Alexander B; Thorkildsen, Brede; Echtermeyer, Andreas T

2017-11-01

The feasibility of a novel composite rubber sealing material to improve sealing under transient cooling (in a so-called blowdown scenario) is investigated here. A composite of hydrogenated nitrile butadiene rubber (HNBR) filled with Micro Encapsulated Phase Change Materials (MEPCM) is described. The fillers contain phase change materials that release heat during the phase transformation from liquid to solid while cooling. This exotherm locally heats the rubber and may improve the function of the seal during a blowdown event. A representative HNBR-MEPCM composite was made and the critical thermal and mechanical properties were obtained by simulating the temperature distribution during a blowdown event. Simulations predict that the MEPCM composites can delay the temperature decrease in a region of the seal during the transient blowdown. A sensitivity analysis of material properties is also presented which highlights possible avenues of improvement of the MEPCMs for sealing applications.

Dental ceramics: a review of new materials and processing methods.

PubMed

Silva, Lucas Hian da; Lima, Erick de; Miranda, Ranulfo Benedito de Paula; Favero, Stéphanie Soares; Lohbauer, Ulrich; Cesar, Paulo Francisco

2017-08-28

The evolution of computerized systems for the production of dental restorations associated to the development of novel microstructures for ceramic materials has caused an important change in the clinical workflow for dentists and technicians, as well as in the treatment options offered to patients. New microstructures have also been developed by the industry in order to offer ceramic and composite materials with optimized properties, i.e., good mechanical properties, appropriate wear behavior and acceptable aesthetic characteristics. The objective of this literature review is to discuss the main advantages and disadvantages of the new ceramic systems and processing methods. The manuscript is divided in five parts: I) monolithic zirconia restorations; II) multilayered dental prostheses; III) new glass-ceramics; IV) polymer infiltrated ceramics; and V) novel processing technologies. Dental ceramics and processing technologies have evolved significantly in the past ten years, with most of the evolution being related to new microstructures and CAD-CAM methods. In addition, a trend towards the use of monolithic restorations has changed the way clinicians produce all-ceramic dental prostheses, since the more aesthetic multilayered restorations unfortunately are more prone to chipping or delamination. Composite materials processed via CAD-CAM have become an interesting option, as they have intermediate properties between ceramics and polymers and are more easily milled and polished.

Advanced Turbine Technology Applications Project (ATTAP)

NASA Technical Reports Server (NTRS)

1992-01-01

ATTAP activities during the past year included test-bed engine design and development, ceramic component design, materials and component characterization, ceramic component process development and fabrication, ceramic component rig testing, and test-bed engine fabrication and testing. Significant technical challenges remain, but all areas exhibited progress. Test-bed engine design and development included engine mechanical design, combustion system design, alternate aerodynamic designs of gasifier scrolls, and engine system integration aimed at upgrading the AGT-5 from a 1038 C (1900 F) metal engine to a durable 1372 C (2500 F) structural ceramic component test-bed engine. ATTAP-defined ceramic and associated ceramic/metal component design activities completed include the ceramic gasifier turbine static structure, the ceramic gasifier turbine rotor, ceramic combustors, the ceramic regenerator disk, the ceramic power turbine rotors, and the ceramic/metal power turbine static structure. The material and component characterization efforts included the testing and evaluation of seven candidate materials and three development components. Ceramic component process development and fabrication proceeded for the gasifier turbine rotor, gasifier turbine scroll, gasifier turbine vanes and vane platform, extruded regenerator disks, and thermal insulation. Component rig activities included the development of both rigs and the necessary test procedures, and conduct of rig testing of the ceramic components and assemblies. Test-bed engine fabrication, testing, and development supported improvements in ceramic component technology that permit the achievement of both program performance and durability goals. Total test time in 1991 amounted to 847 hours, of which 128 hours were engine testing, and 719 were hot rig testing.

Refractory Materials for Flame Deflector Protection System Corrosion Control: Refractory Ceramics Literature Survey

NASA Technical Reports Server (NTRS)

Calle, Luz Marina; Hintze, Paul E.; Parlier, Christopher R.; Curran, Jerome P.; Kolody, Mark; Perusich, Stephen; Whitten, Mary C.; Trejo, David; Zidek, Jason; Sampson, Jeffrey W.;

Electrical and Mechanical Properties of 3D-Printed Graphene-Reinforced Epoxy

NASA Astrophysics Data System (ADS)

Compton, Brett G.; Hmeidat, Nadim S.; Pack, Robert C.; Heres, Maximilian F.; Sangoro, Joshua R.

2018-03-01

Recent developments in additive manufacturing have demonstrated the potential for thermoset polymer feedstock materials to achieve high strength, stiffness, and functionality through incorporation of structural and functional filler materials. In this work, graphene was investigated as a potential filler material to provide rheological properties necessary for direct-write three-dimensional (3D) printing and electrostatic discharge properties to the printed component. The rheological properties of epoxy/graphene mixtures were characterized, and printable epoxy/graphene inks formulated. Sheet resistance values for printed epoxy/graphene composites ranged from 0.67 × 102 Ω/sq to 8.2 × 103 Ω/sq. The flexural strength of printed epoxy/graphene composites was comparable to that of cast neat epoxy ( 80 MPa), suggesting great potential for these new materials in multifunctional 3D-printed devices.

Process of producing a ceramic matrix composite article and article formed thereby

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

Corman, Gregory Scot; McGuigan, Henry Charles; Brun, Milivoj Konstantin

A CMC article and process for producing the article to have a layer on its surface that protects a reinforcement material within the article from damage. The method entails providing a body containing a ceramic reinforcement material in a matrix material that contains a precursor of a ceramic matrix material. A fraction of the reinforcement material is present and possibly exposed at a surface of the body. The body surface is then provided with a surface layer formed of a slurry containing a particulate material but lacking the reinforcement material of the body. The body and surface layer are heatedmore » to form the article by converting the precursor within the body to form the ceramic matrix material in which the reinforcement material is contained, and by converting the surface layer to form the protective layer that covers any fraction of the reinforcement material exposed at the body surface.« less

Process of producing a ceramic matrix composite article and article formed thereby

DOEpatents

Corman, Gregory Scot [Ballston Lake, NY; McGuigan, Henry Charles [Duanesburg, NY; Brun, Milivoj Konstantin [Ballston Lake, NY

2011-10-25

A CMC article and process for producing the article to have a layer on its surface that protects a reinforcement material within the article from damage. The method entails providing a body containing a ceramic reinforcement material in a matrix material that contains a precursor of a ceramic matrix material. A fraction of the reinforcement material is present and possibly exposed at a surface of the body. The body surface is then provided with a surface layer formed of a slurry containing a particulate material but lacking the reinforcement material of the body. The body and surface layer are heated to form the article by converting the precursor within the body to form the ceramic matrix material in which the reinforcement material is contained, and by converting the surface layer to form the protective layer that covers any fraction of the reinforcement material exposed at the body surface.

Turbine repair process, repaired coating, and repaired turbine component

DOEpatents

Das, Rupak; Delvaux, John McConnell; Garcia-Crespo, Andres Jose

2015-11-03

A turbine repair process, a repaired coating, and a repaired turbine component are disclosed. The turbine repair process includes providing a turbine component having a higher-pressure region and a lower-pressure region, introducing particles into the higher-pressure region, and at least partially repairing an opening between the higher-pressure region and the lower-pressure region with at least one of the particles to form a repaired turbine component. The repaired coating includes a silicon material, a ceramic matrix composite material, and a repaired region having the silicon material deposited on and surrounded by the ceramic matrix composite material. The repaired turbine component a ceramic matrix composite layer and a repaired region having silicon material deposited on and surrounded by the ceramic matrix composite material.

Thermal insulating conformal blanket

NASA Technical Reports Server (NTRS)

Barney, Andrea (Inventor); Whittington, Charles A (Inventor); Eilertson, Bryan (Inventor); Siminski, Zenon (Inventor)

2003-01-01

The conformal thermal insulating blanket may have generally rigid batting material covered by an outer insulating layer formed of a high temperature resistant woven ceramic material and an inner insulating layer formed of a woven ceramic fiber material. The batting and insulating layers may be fastened together by sewing or stitching using an outer mold layer thread fabricated of a high temperature resistant material and an inner mold layer thread of a ceramic fiber material. The batting may be formed to a composite structure that may have a firmness factor sufficient to inhibit a pillowing effect after the stitching to not more than 0.03 inch. The outer insulating layer and an upper portion of the batting adjacent the outer insulating layer may be impregnated with a ceramic coating material.

Stochastic modeling of filtrate alkalinity in water filtration devices: Transport through micro/nano porous clay based ceramic materials

USDA-ARS?s Scientific Manuscript database

Clay and plant materials such as wood are the raw materials used in manufacture of ceramic water filtration devices around the world. A step by step manufacturing procedure which includes initial mixing, molding and sintering is used. The manufactured ceramic filters have numerous pores which help i...

Glass-ceramic coating material for the CO2 laser based sintering of thin films as caries and erosion protection.

PubMed

Bilandžić, Marin Dean; Wollgarten, Susanne; Stollenwerk, Jochen; Poprawe, Reinhart; Esteves-Oliveira, Marcella; Fischer, Horst

2017-09-01

The established method of fissure-sealing using polymeric coating materials exhibits limitations on the long-term. Here, we present a novel technique with the potential to protect susceptible teeth against caries and erosion. We hypothesized that a tailored glass-ceramic material could be sprayed onto enamel-like substrates to create superior adhesion properties after sintering by a CO 2 laser beam. A powdered dental glass-ceramic material from the system SiO 2 -Na 2 O-K 2 O-CaO-Al 2 O 3 -MgO was adjusted with individual properties suitable for a spray coating process. The material was characterized using X-ray fluorescence analysis (XRF), heating microscopy, dilatometry, scanning electron microscopy (SEM), grain size analysis, biaxial flexural strength measurements, fourier transform infrared spectroscopy (FTIR), and gas pycnometry. Three different groups of samples (each n=10) where prepared: Group A, powder pressed glass-ceramic coating material; Group B, sintered hydroxyapatite specimens; and Group C, enamel specimens (prepared from bovine teeth). Group B and C where spray coated with glass-ceramic powder. All specimens were heat treated using a CO 2 laser beam process. Cross-sections of the laser-sintered specimens were analyzed using laser scanning microscopy (LSM), energy dispersive X-ray analysis (EDX), and SEM. The developed glass-ceramic material (grain size d50=13.1mm, coefficient of thermal expansion (CTE)=13.310 -6 /K) could be spray coated on all tested substrates (mean thickness=160μm). FTIR analysis confirmed an absorption of the laser energy up to 95%. The powdered glass-ceramic material was successfully densely sintered in all sample groups. The coating interface investigation by SEM and EDX proved atomic diffusion and adhesion of the glass-ceramic material to hydroxyapatite and to dental enamel. A glass-ceramic material with suitable absorption properties was successfully sprayed and laser-sintered in thin films on hydroxyapatite as well as on bovine enamel. The presented novel technique of tooth coating with a dental glass-ceramic using a CO 2 -laser holds a great potential as a possible method to protect susceptible teeth against caries and erosion. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Biaxial flexural strength of Turkom-Cera core compared to two other all-ceramic systems

PubMed Central

AL-MAKRAMANI, Bandar Mohammed Abdullah; RAZAK, Abdul Aziz Abdul; ABU-HASSAN, Mohamed Ibrahim

2010-01-01

Advances in all-ceramic systems have established predictable means of providing metal-free aesthetic and biocompatible materials. These materials must have sufficient strength to be a practical treatment alternative for the fabrication of crowns and fixed partial dentures. Objectives The aim of this study was to compare the biaxial flexural strength of three core ceramic materials. Material and methods Three groups of 10 disc-shaped specimens (16 mm diameter x 1.2 mm thickness - in accordance with ISO-6872, 1995) were made from the following ceramic materials: Turkom-Cera Fused Alumina [(Turkom-Ceramic (M) Sdn Bhd, Puchong, Selangor, Malaysia)], In-Ceram (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany) and Vitadur-N (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany), which were sintered according to the manufacturer's recommendations. The specimens were subjected to biaxial flexural strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. The definitive fracture load was recorded for each specimen and the biaxial flexural strength was calculated from an equation in accordance with ISO-6872. Results The mean biaxial flexural strength values were: Turkom-Cera: 506.8±87.01 MPa, In-Ceram: 347.4±28.83 MPa and Vitadur-N: 128.7±12.72 MPa. The results were analyzed by the Levene's test and Dunnett's T3 post-hoc test (SPSS software V11.5.0 for Windows, SPSS, Chicago, IL, USA ) at a preset significance level of 5% because of unequal group variances (P<0.001). There was statistically significant difference between the three core ceramics (P<0.05). Turkom-Cera showed the highest biaxial flexural strength, followed by In-Ceram and Vitadur-N. Conclusions Turkom-Cera core had significantly higher flexural strength than In-Ceram and Vitadur-N ceramic core materials. PMID:21308292

Low temperature joining of ceramic composites

DOEpatents

Barton, Thomas J.; Anderson, Iver E.; Ijadi-Maghsoodi, Sina; Nosrati, Mohammad; Unal, Ozer

1999-07-13

A method of joining similar or dissimilar ceramic and ceramic composite materials, such as SiC continuous fiber ceramic composites, at relatively low joining temperatures uses a solventless, three component bonding agent effective to promote mechanical bond toughness and elevated temperature strength to operating temperatures of approximately 1200 degrees C. The bonding agent comprises a preceramic precursor, an aluminum bearing powder, such as aluminum alloy powder, and mixtures of aluminum metal or alloy powders with another powder, and and boron powder in selected proportions. The bonding agent is disposed as an interlayer between similar or dissimilar ceramic or ceramic composite materials to be joined and is heated in ambient air or inert atmosphere to a temperature not exceeding about 1200 degrees C. to form a strong and tough bond joint between the materials. The bond joint produced is characterized by a composite joint microstructure having relatively soft, compliant aluminum bearing particulate regions dispersed in a ceramic matrix.

Low temperature joining of ceramic composites

DOEpatents

Barton, T.J.; Anderson, I.E.; Ijadi-Maghsoodi, S.; Nosrati, M.; Unal, O.

1999-07-13

A method of joining similar or dissimilar ceramic and ceramic composite materials, such as SiC continuous fiber ceramic composites, at relatively low joining temperatures uses a solventless, three component bonding agent effective to promote mechanical bond toughness and elevated temperature strength to operating temperatures of approximately 1200 C. The bonding agent comprises a preceramic precursor, an aluminum bearing powder, such as aluminum alloy powder, and mixtures of aluminum metal or alloy powders with another powder, and boron powder in selected proportions. The bonding agent is disposed as an interlayer between similar or dissimilar ceramic or ceramic composite materials to be joined and is heated in ambient air or inert atmosphere to a temperature not exceeding about 1200 C to form a strong and tough bond joint between the materials. The bond joint produced is characterized by a composite joint microstructure having relatively soft, compliant aluminum bearing particulate regions dispersed in a ceramic matrix. 3 figs.

Low temperature joining of ceramic composites

DOEpatents

Barton, T.J.; Anderson, I.E.; Ijadi-Maghsoodi, S.; Nosrati, M.; Unal, O.

1999-01-12

A method of joining similar or dissimilar ceramic and ceramic composite materials, such as SiC continuous fiber ceramic composites, at relatively low joining temperatures uses a solventless, three component bonding agent effective to promote mechanical bond toughness and elevated temperature strength to operating temperatures of approximately 1200 degrees C. The bonding agent comprises a preceramic precursor, an aluminum bearing powder, such as aluminum alloy powder, and mixtures of aluminum metal or alloy powders with another powder, and boron powder in selected proportions. The bonding agent is disposed as an interlayer between similar or dissimilar ceramic or ceramic composite materials to be joined and is heated in ambient air or inert atmosphere to a temperature not exceeding about 1200 degrees C. to form a strong and tough bond joint between the materials. The bond joint produced is characterized by a composite joint microstructure having relatively soft, compliant aluminum bearing particulate regions dispersed in a ceramic matrix. 3 figs.

Experimental investigation on IXV TPS interface effects in Plasmatron

NASA Astrophysics Data System (ADS)

Ceglia, Giuseppe; Trifoni, Eduardo; Gouriet, Jean-Baptiste; Chazot, Olivier; Mareschi, Vincenzo; Rufolo, Giuseppe; Tumino, Giorgio

2016-06-01

An experimental investigation related to the thermal protection system (TPS) interfaces of the intermediate experimental vehicle has been carried out in the Plasmatron facility at the von Karman Institute for fluid dynamics. The objective of this test campaign is to qualify the thermal behaviours of two different TPS interfaces under flight representative conditions in terms of heat flux and integral heat load ( 180 kW/m2 for 700 s). Three test samples are tested in off-stagnation configuration installed on an available flat plate holder under the same test conditions. The first junction is composed of an upstream ceramic matrix composite (CMC) plate and an ablative P50 cork composite block separated by a gap of 2 mm. The second one is made of an upstream P50 block and a downstream ablative SV2A silicon elastomer block with silicon-based filler in between. A sample composed of P50 material is tested in order to obtain reference results without TPS interface effect. The overheating at the CMC-P50 interface due to the jump of the catalytic properties of the materials, and the recession/swelling behaviour of the P50-SV2A interface are under investigation. All the test samples withstand relatively well the imposed heat flux for the test duration. As expected, both the ablative materials undergo a thermal degradation. The P50 exhibits the formation of a porous char layer and its recession; on the other hand, the SV2A swells and forms a fragile char layer.

The energetics of adhesion in composite materials

NASA Astrophysics Data System (ADS)

Harding, Philip Hiram

Composite materials are used throughout modern society, and often the most important parameter in determining their properties is the adhesion at material interfaces within the composite. A broad investigation is completed, the global objective of which is to develop understanding of the role of adhesion in composite materials. The scope of this study ranges from macroscopic effects of adhesion on filled polymer composites to microscopic adhesion measurements with engineered interfaces. The surface of a filler material is systematically modified and surface characterization techniques are used to quantify the influence of the surface treatments on surface energetics and wetting properties. Filled polymer composites are prepared and composite mechanical properties determined with beam deflection tests. Filler surface treatments significantly alter the composite yield stress for composites which fail interfacially and are observed to increase or decrease mechanical strength, depending on the chemical nature of the modification. Thermodynamic adhesion mechanisms active at the filler-matrix interfaces are then explored by making direct interfacial strength measurements whereby a single spherical particle is introduced into the polymeric matrix. Interfacial strength is determined by submitting the single-particle composite (SPC) to uni-axial tension and relating the macroscopic stress at interfacial failure to that experienced at the interface. The technique provides a measurement of interfacial strength between two elastic materials, one unaffected by frictional forces, viscoelasticity, and thermal stresses. The SPC measurements are used to verify proposed adhesion mechanisms at the various filler-polymer interfaces and establish the role of adhesion in the filled polymer composites. The SPC technique is then used to investigate the adhesion promotion mechanism of organofunctional silanes, which are shown to be controlled by the compatibility and penetration of the silane organofunctional group. The effects of thermal residual stresses on interfacial strength are also investigated using the SPC technique. Processing conditions, i.e., time-temperature profiles, are used to systematically vary the thermal residual stresses within the polymeric matrix. The interfaces studied are deleteriously affected by increases in thermal residual stresses.