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SOLID ELECTROLYTES STRENGTHENED BY METAL DISPERSIONS An improvement in solid electrolytes of advanced secondary batteries of the sodium-sulfur, sodium-halogen, and like combinations is achieved by providing said battery with a cermet electrolyte containing a metal dispersion ranging from 0.1 to 10.0 vol. % of a substantially nonreactive metal selected from the group consisting essentially of Pt, Cr, Fe, Co, Ni, Nb, their alloys, and their physical mixtures in the elemental or uncombined state, the remainder of said cermet being an ion-conductive ceramic material. |
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PROCESS FOR FABRICATING ZNO-BASED VARISTORS The invention is a process for producing ZnO-based varistors incorporating a metal oxide dopant. In one form, the invention comprises providing a varistor powder mix of colloidal particles of ZnO and metal-oxide dopants including Bi2O3. The mix is hot-pressed to form a compact at temperatures below 850C and under conditions effecting reduction of the ZnO to sub-stoichiometric oxide. This promotes densification while restricting liquid formation and grain growth. The compact then is heated under conditions restoring the zinc oxide to stoichiometric composition, thus improving the varistor properties of the compact. The prss produces fine-grain varistors characterized by a high actual breakdown voltage and a high average breakdown voltage per individual grain boundary. |
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OXIDATION RESISTANT FILLER METALS FOR DIRECT BRAZING OF STRUCTURAL CERAMICS 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. |
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DISPERSION TOUGHENED CERAMIC COMPOSITES AND METHOD FOR MAKING SAME Ceramic composites exhibiting increased fracture toughness are produced by the simultaneous codeposition of silicon carbide and titanium disilicide by chemical vapor deposition. A mixture of hydrogen, methyltrichlorosilane and titanium tetrachloride is introduced into a furnace containing a substrate such as graphite or silicon carbide. The thermal decomposition of the methyltrichlorosilane provides a silicon carbide matrix phase and the decomposition of the titanium tetrachloride provides a uniformly dispersed second phase of the intermetallic titanium disilicide within the matrix phase. The fracture toughness of the ceramic composite is in the range of about 6.5 to 7.0 MPaVm which represents a significant increase over that of silicon carbide. |
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METHOD FOR PREPARING CONFIGURED SILICON CARBIDE WHISKER-REINFORCED ALUMINA CERAMIC ARTICLES A ceramic article of alumina reinforced with silicon carbide whiskers suitable for the fabrication into articles of complex geometry are provided by pressureless sintering and hot isostatic pressing steps. In accordance with the method of the invention a mixture of 5 to 10 vol. % silicon carbide whiskers 0.5 to 5 wt. % of a sintering aid such as yttria and the balance alumina powders is ball-milled and pressureless sintered in the desired configuration an inert atmosphere at a temperature of about 1800C to provide a self-supporting configured composite of a density of at least about 94% theoretical density. The composite is then hot isostatically pressed at a temperature and pressure adequate to provide configured articles of at least about 98% of theoretical density which is sufficient to provide the article with sufficient strength and fracture toughness for use in most structural applications such as gas turbine blades, cylinders, and other components of advanced heat engines. |
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SILICON CARBIDE WHISKER-ZIRCONIA REINFORCED MULLITE AND ALUMINA CERAMICS The flexural strength and/or fracture toughness of SiC whisker-reinforced composites utilizing mullite or alumina as the matrix material for the composite are increased by the addition of zirconia in a monoclinic or tetragonal phase to the matrix. The zirconia addition also provides for a lower hot-pressing temperature and increases the flexural strength and/or fracture toughness of the SiC whisker-reinforced composites over SiC whisker-reinforced composites of the similar matrix materials reinforced with similar concentrations of SiC whiskers. |
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PROCESS FOR PREPARING FINE GRAIN TITANIUM CARBIDE POWDER A method for preparing finely divided titanium carbide powder in which an organotitanate is reacted with a carbon precursor polymer to provide an admixture of the titanium and the polymer at a molecular-level due to a crosslinking reaction between the organotitanate and the polymer. The resulting gel is dried, pyrolyzed to drivee off volatile components and provide carbon. The resulting solids are then heated at an elevated temperature to convert the titanium and carbon to high-purity titanium carbide powder in a submicron size range. |
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COPPER-SILVER-TITANIUM FILLER METAL FOR DIRECT BRAZING OF STRUCTURAL CERAMICS 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. |
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COPPER-SILVER TITANIUM-TIN FILLER METAL FOR DIRECT BRAZING OF STRUCTURAL CERAMICS A method of joining ceramics and metals to themselves and to one another at about 800C 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. |
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PROCESS FOR FABRICATION OF LARGE TITANIUM DIBORIDE CERAMIC BODIES A process for manufacturing large, fully dense, high purity TiB2 articles by pressing powders with a sintering aid at relatively low temperatures to reduce grain growth. The process requires stringent temperature and pressure applications in the hot-pressing step to ensure maximum removal of sintering aid and to avoid damage to the fabricated article of the die. |
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PROTECTIVE COATING FOR ALUMINA-SILICON CARBIDE WHISKER COMPOSITES Ceramic composites formed of an alumina matrix reinforced with cilicon carbide whiskers homogenously dispersed therein are provided with a protective coating for preventing fracture strength degradation of the composite by oxidation during exposure to high temperatures in oxygen-containing atmospheres. The coating prevents oxidation of the silicon carbide whiskers within the matrix by sealing off the exterior of the matrix so as to prevent oxygen transport into the interior of the matrix. The coating is formed of mullite or mullite plus silicon oxide and alumina and is formed in place by heating the composite in air to a temperature greater than 1200C. This coating is less than about 100 microns thick and adequately protects the underlying composite from fracture strength degradation due to oxidation. |
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METHOD FOR MOLDING CERAMIC POWDERS A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant for the metal-containing powder, and a monomer solution. The monomer solution includes at least one multifunctional monomer, a free-radical initiator, and an organic solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product may be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, whereafter the product may be sintered. |
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CERAMIC COMPOSITES REINFORCED WITH MODIFIED SILICON CARBIDE WHISKERS Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the compoiste. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevanted temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material. |
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FLUID CASTING OF PARTICLE-BASED ARTICLES An improved ceramic-metal composite comprising a mixture of a ceramic material with a ductile intermetallic alloy, preferably Ni3Al. |
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CERAMIC COMPOSITES REINFORCED WITH MODIFIED SILICON CARBIDE WHISKERS AND METHOD FOR MODIFYING THE WHISKERS Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material. |
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DUCTILE NI3AL ALLOYS AS BONDING AGENTS FOR CERAMIC MATERIALS IN CUTTING TOOLS An improved ceramic-metal composite comprising a mixture of a ceramic material with a ductile intermetallic alloy, preferably Ni3Al. |
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MODIFIED SILICON CARBIDE WHISKERS Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the compoiste. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevanted temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material. |
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METHOD FOR MOLDING CERAMIC POWDERS USING A WATER-BASED GEL CASTING A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant, and a monomer solution. The monomer solution includes at least one monofunctional monomer and at least one difunctional monomer, a free-radical initiator, and a aqueous solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product may be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, whereafter the product may be sintered. |
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PROCESS FOR FABRICATING DOPED ZINC OXIDE MICROSPHERE GEL A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel. |
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THERMAL STORAGE MODULE FOR SOLAR DYNAMIC RECEIVERS A thermal energy storage system comprising a germanium phase change material and a graphite container. |
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Method for Molding Ceramic Powders Using a Water-Based Gelcasting Process A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant, and a monomer solution. The monomer solution includes at least one monofunctional monomer and at least one difunctional monomer, a free-radical initiator, and a aqueous solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product may be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, whereafter the product may be sintered. |
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METHOD OF NITRIDING, CARBURIZING, OR OXIDIZING REFRACTORY METAL ARTICLES USING MICROWAVES A method of nitriding an article of refractory-nitride-forming metal or metalloids. A consolidated metal or metalloid article is placed inside a microwave oven and nitrogen containing gas is introduced into the microwave oven. The metal or metalloid article is heated to a temperature sufficient to react the metal or metalloid with the nitrogen by applying a microwave energy within the microwave oven. The metal or metalloid article is maintained at that temperature for a period of time sufficient to convert the article of metal or metalloid to an article of refractory nitride. In addition, a method of applying a coating, such as a coating of an oxide, a carbide, or a carbo-nitride, to an article of metal or metalloid by microwave heating. |
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CESIUM IODIDE ALLOYS A transparent, strong CsI alloy having additions of monovalent iodides. Although the preferred iodide is AgI, RbI and CuI additions also contribute to an improved polycrystalline CsI alloy. |
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PROCESS FOR MANUFACTURING TANTALUM CAPACITORS A process for manufacturing tantalum capacitors in which microwave energy is used to sinter a tantalum powder compact in order to achieve higher surface area and improved dielectric strength. The process comprises cold pressing tantalum powder with organic binders and lubricants to form a porous compact. After removal of the organics, the tantalum compact is heated to 1300 to 2000C by applying microwave radiation. Said compact is then anodized to form a dielectric oxide layer and infiltrated with a conductive material such as MnO2. Wire leads are then attached to form a capacitor to said capacitor and is hermetically packaged to form the finished product. |
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DEVICE AND METHOD FOR SKULL-MELTING DEPTH MEASUREMENT A method of skull-melting comprises the steps of:
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PRESURELESS SINTERING OF WHISKER-TOUGHENED CERAMIC COMPOSITES A pressureless sintering method is disclosed for use in the production of whisker-toughened ceramic composites wherein the sintered density of composites containing up to about 20 vol. % of SiC whiskers is improved by reducing the average aspect ratio of the whiskers to from about 10 to about 20. Sintering aids further improve the density, permitting the production of composites containing 20 vol. % SiC with sintered densities of 94% or better of theoretical density by a pressureless sintering method. |
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ZINC OXIDE VARISTORS AND/OR RESISTORS Varistors and/or resistors that includes doped zinc oxide gel microspheres. The doped zinc oxide gel microspheres preferably have from about 60 to about 95% by weight zinc oxide and from about 5 to about 40% by weight dopants based on the weight of the zinc oxide. The dopants are a plurality of dopants selected from silver salts, boron oxide, silicon oxide and hydrons oxides of aluminum, bismuth, cobalt, chromium, manganese, nickel, and antimony. |
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DAMAGE TOLERANT LIGHT ABSORBING MATERIAL A light absorbing article comprised of a composite of carbon-bonded carbon fibers, prepared by: blending carbon fibres with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000C to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm3. |
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DOPED ZINC OXIDE MICROSPHERES A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel. |
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METHOD OF NITRIDING REFRACTORY METAL ARTICLES A method of nitriding a refractory-nitride forming metal or metalloid articles and composite articles. A consolidated metal or metalloid article or composite is placed inside a microwave oven and nitrogen containing gas is introduced into the microwave oven. The metal or metalloid article or composite is heated to a temperature sufficient to react the metal or metalloid with the nitrogen by applying a microwave energy within the microwave oven. The metal or metalloid article or composite is maintained at that temperature for a period of time sufficient to convert the article of metal or metalloid or composite to an article or composite of refractory nitride. In addition, a method of applying a coating, such as a coating of an oxide, a carbide, or a carbo-nitride, to an article of metal or metalloid by microwave heating. |
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METHOD FOR PRODUCING TEXTURED SUBSTRATES FOR THIN-FILM PHOTOVOLTAIC CELLS The invention pertains to the pruction of ceramic substrates used in the manufacture of thin-film photovoltaic cells used for directly converting solar energy to electrical energy. Elongated ribbon-like sheets of substrate precursor containing a mixture of ceramic particulates, a binder, and a plasticizer are formed and then while green provided with a mechanically textured surface region used for supporting the thin film semiconductor of the photovoltaic cell when the sheets of the substrate precursor are subsequently cut into substrate-sized shapes and then sintered. The textured surface pattern on the substrate provides enhanced light trapping and collection for substantially increasing the solar energy conversion efficiency of thin-film photovoltaic cells. |
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BLACKBODY MATERIAL A light emitting article comprises a composite of carbon-bonded carbon fibers, prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000C to form a carbon-bonded carbon fiber light emitting composite article having a bulk density less than 1 g/cm3. |
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VARIABLE FREQUENCY MICROWAVE FURNACE SYSTEM A variable frequency microwave furnace system designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity for testing or other selected applications. The variable frequency microwave furnace system includes a microwave signal generator or microwave voltage-controlled oscillator for generating a low-power microwave signal for input to the microwave furnace. A first amplifier may be provided tooamplify the magnitude of the signal output from the microwave signal generator or the microwave voltage-controlled oscillator. A second amplifier is provided for prcessing the signal output by the first amplifier. The second amplifier outputs the microwave signal input to the furnace cavity. In the preferred embodiment, the second amplifier is a traveling-wave tube (TWT). A power supply is provided for operation of the second amplifier. A directional coupler is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter is provided for measuring the power delivered to the microwave furnace. A second power meter detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load. |
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SCINTILLATOR ASSEMBLY FOR ALPHA RADIATION DETECTION AND AN ASSOCIATED METHOD OF MAKING A scintillator assemby for use in conjunction with a photomultiplier or the like in the detection of alpha radiation utilizes a substrate or transparent yttrium aluminum garnet and a relatively thin film of cerium-doped yttrium aluminum garnet coated upon the substrate. The film material is applied to the substrate in a sputtering process, and the applied film and substrate are annealed to effect crystallization of the film upon the substrate. The resultant assembly provides relatively high energy resolution during use in a detection instrument and is sufficiently rugged for use in field environments. |
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THIN FILM HYDROGEN SENSOR A hydrogen sensor element comprises an essentially inert, electrically-insulating substrate having a thin-film metallization deposited thereon which forms at least two resistors on the substrate. The metallization comprises a layer of Pd or a Pd alloy for sensing hydrogen and an underlying intermediate metal layer for providing enhanced adhesion of the metallization to the substrate. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors, and at least one of the resistors is left uncovered. The difference in electrical resistances of the covered resistor and the uncovered resistor is related to hydrogen concentration in a gas to which the sensor element is exposed. |
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PRESSURELESS SINTERING OF WHISKERED-TOUGHENED CERAMIC COMPOSITES A pressureless sintering method is disclosed for use in the production of whisker-toughened ceramic composites wherein the sintered density of composites containing up to about 20 vol. % SiC whiskers is improved by reducing the average aspect ratio of the whiskers to from about 10 to about 20. Sintering aids further improve the density, permitting the production of composites containing 20 vol. % SiC with sintered densities of 94% or better of theoretical density by a pressureless sintering method. |
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CALCIUM SILICATE INSULATION STRUCTURE An insulative structure including a powder-filled evacuated casing utilizes a quantity of finely divided synthetic calcium silicate having a relatively high surface area. The resultant structure provides superior thermal insulating characteristics over a broad temperature range and is particularly well-suited as a panel for a refrigerator or freezer or the insulative barrier for a cooler or an insulated bottle. |
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FLUID CASTING OF PARTICLE-BASED ARTICLES A method for the production of articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is introduced into an immiscible, heated fluid. The slurry sets or hardens into a shape determined by the physical characteristics of the fluid and the manner of introduction of the slurry into the fluid. For example, the slurry is pulse injected into the fluid to provide spherical articles. The hardened spheres may then be sintered to consolidate the particles and provide a high density product. |
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MICROWAVE FURNACE HAVING MICROWAVE COMPATIBLE DILATOMETER An apparatus for measuring and monitoring a change in the dimension of a sample being heated by microwave energy is described. The apparatus comprises a microwave heating device for heating a smplae by microwave energy, a microwave compatible dilatometer for measuring and monitoring a change in the dimension fo the sample being heated by microwave energy without leaking microwaves out of the microwave heating device, and a temperature determination device for measuring and monitoring the temperature of the sample being heated by microwave energy. |
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CASTING OF PARTICLE-BASED HOLLOW SHAPES A method for production of hollow articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is coated onto a prewarmed continuous surface in a relatively thin layer so that the slurry is substantially uniformly coated on the surface. The heat of the prewarmed surface conducts to the slurry to initiate a reaction which causes the slurry to set or harden in a shape conforming to the surface. The hardened configurations may then be sintered to consolidate the particles and provide a high density product. |
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THICK FILM HYDROGEN SENSOR A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors. |
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METHOD AND APPARATUS FOR MAKING ARTICLES FROM PARTICLE BASED MATERIALS A method and apparatus for the production of articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with the invention, a thermally settable slurry containing a relatively high concentration of the particles is conveyed through an elongate flow area having a desired cross-sectional configuration. The slurry is heated as it is advanced through the flow area causing the slurry to set or harden in a shape which conforms to the cross-sectional configuration of the flow area. The material discharges from the flow area as a self-supporting solid of near net final dimensions. The article may then be sintered to consolidate the particles and provide a high density product. |
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PROCESS FOR MANUFACTURING MULTILAYER CAPACITORS The invention is directed to a method of manufacture of multilayer electrical components, especially capacitors, and components made by such a method. High capacitance dielectric materials and low cost metallizations layered with such dielectrics may be fabricated as multilayer electrical components by sintering the metallizations and the dielectrics during the fabrication process by application of microwave radiation. |
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METHOD FOR PREPARING CERAMIC COMPOSITE A process for preparing ceramic composite comprising blending TiC particulates, Al2O3 particulates and nickle aluminide and consolidating the mixture at a temperature and pressure sufficient to produce a densified ceramic composite having fracture toughness equal to or greater than 7 MPa m1/2, a hardness equal to or greater than 18 GPa. |
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METHOD FOR PRODUCING TEXTURED SUBSTRATES FOR THIN-FILM PHOTOVOLTAIC CELLS The invention pertains to mthe production of ceramic substrates used in the manufacture of thin-film photovoltaic cells used for directly converting solar energy to electrical energy. Elongated ribbon-like sheets of substrate precursor containing a mixture of ceramic particulates, a binder, and a plasticizer are formed and then while green provided with a mechanically textured surface region used for supporting the thin film semiconductor of the photovoltaic cell when the sheets of the substrate precursor are subsequently cut into substrate-sized shapes and then sintered. The textured surface pattern on the substrate provides enhanced light trapping and collection for subtantially increasing the solar energy conversion efficiency of thin-film photovoltaic cells. |
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APPARATUS AND METHOD FOR MICROWAVE PROCESSING OF MATERIALS A variable frequency microwave heating apparatus designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity for testing or other selected applications. The variable frequency heating apparatus is used in the method of the present invention to monitor the resonant processing frequency within the furnace cavity depending upon the material, including the state thereof, from which the workpiece is fabricated. The variable frequency microwave heating apparatus includes a microwave signal generator and a high-power microwave amplifier or a microwave voltage-controlled oscillator. A power supply is provided for operation of the high-power microwave oscillator or microwave amplifier. A directional coupler is provided for detecting the direction and amplitude of signals incident upon and reflected from the microwave cavity. A first power meter is provided for measuring the power delivered to the microwave furnace. A second power meter detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load. |
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METHOD FOR JOINING CARBON-CARBON COMPOSITES TO METALS A method for joining carbon-carbon composites to metals by brazing. Conventional brazing of recently developed carbon-bonded carbon fiber (CBCF) material to a metal substrate is limited by the tendency of the braze alloy to "wick" into the CBCF composite rather than to form a strong bond. The surface of the CBCF composite that is to be bonded is first sealed with a fairly dense carbonaceous layer achieved by any of several methods. The sealed surface is then brazed to the metal substrate by vacuum brazing with a Ti-Cu-Be alloy. |
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Motor Vehicle Fuel Analyzer PATENT ABSTRACT NOT YET AVAILABLE. |
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CASTING OF PARTICLE-BASED HOLLOW SHAPES A method for the production of hollow articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is coated onto a prewarmed continuous surface in a relatively thin layer so that the slurry is substantially uniformly coated on the surface. The heat of the prewarmed surface conducts to the slurry to initiate a reaction which causes the slurry to set or harden in a shape conforming to the surface. The hardened configurations may then be sintered to consolidate the particles and provide a high density product. |
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METHOD FOR CURING POLYMERS USING VARIABLE-FREQUENCY MICROWAVE HEATING A method for curing polymers incorporating a variable frequency microwave furnace system designed to allow modulation of the frequency of the microwaves introduced into a furnace cavity. By varying the freuqency of the microwave signal, non-uniformities within the cavity are minimized thereby achieving a more uniform cure throughout the workpiece. A directional coupler is provided for detecting the direction of a signal and further directing the signal depending on the detected direction. A first power meter is provided for measuring the power delivered to the microwave furnace. A second power meter detects the magnitude of reflected power. The furnace cavity may be adapted to be used to cure materials defining a continuous sheet or which require compressive forces during curing. |
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RADIO-FREQUENCY AND MICROWAVE LOAD COMPRISING A CARBON-BONDED CARBON FIBER COMPOSITE A billet of low-density carbon-bonded carbon fiber (CBCF) composite is machined into a desired attenuator or load element shape (usually tapering). The CBCF composite is used as a free-standing load element or, preferably, brazed to the copper, brass or aluminum components of coaxial transmission lines or microwave waveguides. A novel braze method was developed for the brazing step. The resulting attenuator and/or load devices are robust, relatively inexpensive, more easily fabricated, and have improved performance over conventional graded-coating loads. |
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Method of Making Tantalum Capacitators A method for manufacturing tantalum capacitors includes preparing a tantalum compact by cold pressing tantalum powder, placing the compact, along with loose refractory metal powder, in a microwave-transparent casket to form an assembly, and heating the assembly for a time sufficient to effect at least partial sintering of the compact and the product made by the method. |
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Collector Surface for a Microwave Tube Comprising a Carbon-Bonded Carbon-Fiber Composite In a microwave tube, an improved collector surface coating comprises a porous carbon composite material, preferably a carbon-bonded carbon fiber composite having a bulk density less than about 2 g/cc. Installation of the coating is readily adaptable as part of the tube manufacturing process. |
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Method of Drying Articles A method of drying a green particle includes the steps of:
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PROCESS FOR STRENGTHENING SILICON BASED CERAMICS A process for strengthening silicon based ceramic monolithic materials and composite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400¡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. |
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