Abstract: A sintered mullite-based body having an excellent dielectric constant and thermal expansion coefficient, and an improved flexural strength and surface smoothness, is obtained by heat treating a composition of 99.1 to 80% by weight of a mullite powder and 0.1 to 20% by weight of yttrium oxide as a sintering agent, optionally together with a colorant of MoO.sub.3.

Abstract: A ceramic substrate for densely integrated semiconductor arrays which is superior in a coefficient of thermal expansion, dielectric constant, strength of metallized bond, and mechanical strength, comprising a sintered body composed essentially of mullite crystals and a non-crystralline binder composed of SiO.sub.2, Al.sub.2 O.sub.3, and MgO, is provided.

Abstract: There is disclosed a raw composition, as well as a fired shape, known in the art as a clay-bonded graphite crucible for melting metals, which contains a quantity of fused silica and is particularly adaptable to melting metals in high-energy, induction furnaces.

Abstract: In the present invention, there is provided a method for producing a self-supporting ceramic or ceramic composite body by the oxidation of a parent metal to form a polycrystalline ceramic material comprising the oxidation reaction product of said parent metal with an oxidant, including a vapor-phase oxidant, and optionally one or more metallic constituents dispersed throughout the polycrystalline ceramic material. The method comprises the steps of providing at least a portion of said parent metal with a barrier means at least partially spaced from said parent metal for establishing at least one surface of the ceramic body, and heating said parent metal to a temperature above its melting point but below the melting point of the oxidation reaction product to form a body of molten metal. At that temperature, the molten metal is reacted with the oxidant, thus forming the oxidation reaction product.

Abstract: A lightweight oil and gas well proppant made by simultaneously mixing and compacting a milled calcined kaolin clay powder to form green pellets and then drying, screening and sintering the pellets to form proppant pellets having a specific gravity of 3.0 or less and a conductivity of at least 4,200 millidarci-feet and preferably at least 5,100 md-ft as measured by the Stim-Lab method after 50 hours at 8,000 psi and 275.degree. F. in the presence of deoxygenated aqueous 2% solution of KCl.

Abstract: A lightweight oil and gas well proppant made by simultaneously mixing and compacting a mixture of kaolin clay which has been calcined at a temperature low enough to prevent the formation of mullite and crystobalites to an LOI of 12 or less when tested at 1400.degree. C., and amorphous to microcrystalline silica both of which have been milled to an average agglomerated particle size of 7 microns or less to form green pellets, and then drying, screening, and sintering the pellets to form proppant pellets having a specific gravity of 2.7 or less, the proppant having a conductivity of at least 3,000 millidarci-feet as measured by the Stim-Lab Technique after 50 hours at 8,000 psi and 275.degree. F. in the presence of deoxygenated aqueous 2% solution of KCl using sandstone shims.

Abstract: The invention relates to a method for producing ceramic composites obtained by oxidation of a parent metal to form a polycrystalline ceramic material by providing a filler having a coating of a silicon source on at least a portion of the filler different in composition from the primary composition of the filler, said silicon source possessing intrinsic doping properties. A body of molten parent metal, adjacent a mass of the filler material, reacts with an oxidant to form an oxidation reaction product which infiltrates the adjacent mass of filler, thereby forming the ceramic composite.

Abstract: In processes of forming a refractory mass on a surface, a mixture of refractory particles and oxidizable particles which react exothermically with oxygen to generate sufficient heat to soften or melt at least the surfaces of the refractory particles are sprayed against that surface to bring about formation of said refractory mass. To promote the reliable and consistent formation of a durable refractory mass, the granulometry of the particles which are sprayed in the mixture is such that the 80% and 20% grain sizes of the refractory particles (that is, the screen mesh sizes G.sub.80 and G.sub.20 through which respectively 80% and 20% by weight of the particles will pass) have a mean greater than the mean of the 80% and 20% grain sizes of the oxidizable particles and the size range spread factor f(G) of the refractory particles is at least 1.

Abstract: A method for producing a self-supporting ceramic composite structure comprising a ceramic matrix embedding a filler, includes oxidizing a parent metal to form a polycrystalline material comprising the oxidation reaction product of the parent metal and, optionally, one or more metallic constituents. The method includes heating the parent metal to provide a source of molten parent metal and a reservoir of molten metal which is in communication with the parent metal having a chemical composition which is different from the parent metal and contacting the molten parent metal with a permeable bedding of filler. The molten parent metal reacts with the oxidant to form the oxidation reaction product and is replenished by the reservoir as the reacting continues for a time sufficient to grow the oxidation reaction product to a desired extent and thereby embed at least a portion of the bedding of filler within the oxidation reaction product to form the ceramic composite structure.

Abstract: A method of making self-supporting ceramic composite structures having filler embedded therein includes infiltrating a permeable mass of filler with polycrystalline material comprising an oxidation reaction product obtained by oxidation of a parent metal such as aluminum and optionally containing therein non-oxidized constituents of the parent metal. The structure is formed by placing a parent metal adjacent to a permeable filler and heating the assembly to melt the parent metal and provide a molten body of parent metal which is contacted with a suitable vapor-phase oxidant. Within a certain temperature region and optionally aided by one or more dopants in or on the parent metal, molten parent metal will migrate through previously formed oxidation reaction product into contact with the oxidant, causing the oxidation reaction product to grow so as to embed the adjacent filler and provide the composite structure.

Abstract: 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.

Abstract: This invention relates to the high temperature stabilization of aluminum titanate and aluminum titanate-mullite compositions by the addition of iron oxide. It has been found that iron oxide concentrations greater than 5 weight percent and as high as approxkmately 25 weight percent have a stabilization effect at high temperatures on aluminum titanates. The resultant ceramic body is further enhanced by the addition of from 0.1 to 5 weight percent rare earth oxide.

Abstract: A process for preparing mullite, 3Al.sub.2 O.sub.3.2SiO.sub.2, whiskers by(1) forming an intimate, anhydrous mixture of AlF.sub.3 and SiO.sub.2 powders in about a 12:13 molar ratio;(2) heating the mixture in an anhydrous, SiF.sub.4 atmosphere at about 700.degree. C. to about 950.degree. C. to form barlike crystalline topaz, Al.sub.2 (SiO.sub.4)F.sub.2 ; and(3) heating the barlike crystalline topaz under anhydrous conditions in a SiF.sub.4 atmosphere at a temperature of from about 1150.degree. C. to about 1400.degree. C. to produce mullite whiskers.The mullite whiskers produced can be used in ceramic and metal matrices without further chemical treatment.

Abstract: A process for preparing mullite whiskers by(1) forming an anhydrous, intimate, uniform mixture of AlF.sub.3, Al.sub.2 O.sub.3, and fused SiO.sub.2 powders in an amount selected to produce stoichiometric mullite or a solid solution of Al.sub.2 O.sub.3 in stoichiometric mullite;(2) heating the mixture in anhydrous SiF.sub.4 atmosphere at a temperature of from about 700.degree. to about 950.degree. C. to form barlike topaz crystals;(3) heating the barlike topaz in an anhydrous SiF.sub.4 atmosphere a a temperature of from about 1150.degree. C. to about 1700.degree. C. to produce the mullite whiskers.

Abstract: A process for producing an improved quality alumina-silica-chromia fiber from a mixture of an alumina powder, a silica powder and a powder of a solid solution of chromia in alumina, providing a flowing melt, and forming fibers.

Abstract: A hot-pressed ceramic composite having good resistance to thermal shock and good erosion/corrosion resistance in molten alloys, and a method for producing said composite which comprises the blending of fused zirconia mullite with boron nitride.

Abstract: A ceramic composite containing less than 90% of a single phase silicon aluminum oxynitride and titanium nitride in an amount of up to about 10% by weight. Also disclosed are silicon nitride containing compositions for forming the composite and methods of producing the composite from the composition.

Abstract: A method for producing a self-supporting ceramic composite structure, which includes a ceramic matrix embedding a filler, includes oxidizing a parent metal to form a polycrystalline material comprising the oxidation reaction product of the parent metal with an oxidant and, optionally, one or more metallic constituents, and the filler embedded by the matrix. The method includes heating a first source of molten parent metal and a reservoir source of molten parent metal and contacting the first source of molten parent metal with a permeable bedding of filler. The first source of molten parent metal is reacted with the oxidant to form the oxidation reaction product and is replenished from the reservoir as the reacting continues for a time sufficient to grow the oxidation reaction product to a desired extent and thereby embed at least a portion of the bedding of filler within the oxidation reaction product to form the ceramic composite structure.

Abstract: The present invention provides a method of synthesizing amorphous cordierite-forming glasses from organometallic precursors. Either the sol-gel/.beta.-diketonate technique or the amorphous chelating hydroxycarboxylate process can be used advantageously. The method of the present invention can also be used to form 5 component comprised and 2 component comprised amorphous compositions wherein one of the components is an oxide of silicon.

Abstract: Disclosed is a starting mixture for the preparation of a sintered body on a basis of aluminum titanate consists of more than 46 wt.-% TiO.sub.2, up to 49.5 wt.-% Al.sub.2 O.sub.3, 3 to 5 wt.-% quartz, and less than 0.2 wt.-% impurities, Al.sub.2 O.sub.3 and TiO.sub.2 being present in the weight ratio of 1:0.95 to 1:1.05. The sintered body according to the invention is composed of:15 to 35 wt.-% TiO.sub.2 ;60 to 85 wt.-% Al.sub.2 TiO.sub.5 (aluminum titanate);up to 5 wt.-% Al.sub.2 O.sub.3 ;up to 17 wt.-% Mullite; andmax. 0.2 wt.-% impurities,all parts by weight together totaling 100 wt.-%.Also disclosed are processes for making the sintered body.

Abstract: An alumina silica sintered ceramic that is produced by the normal sintering method and which has bending strength of at least 300 MPa at room temperature and at least 400 MPa at an elevated temperature, for example, 1,300.degree. C. is disclosed.This sintered ceramic is produced by a process comprising the following steps: providing a chiefly amorphous starting powder that consists of 62-73 wt % Al.sub.2 O.sub.3 and correspondingly 38-27 wt % SiO.sub.2 ; calcining this starting powder to make a calcined product that is chiefly composed of a crystalline phase and which contains oxides of an alkali metal and an alkaline earth metal in a total amount of no more than 1,500 ppm; pressing the ground particles of the calcined product into a compact; and sintering the compact at 1,500.degree.-1,750.degree. C. and at atmospheric pressure.

Abstract: Sintered, spherical composite pellets or particles comprising one or more clays as a major component and bauxite, alumina, or mixtures thereof, are described, along with the process for their manufacture. The pellets may have an alumina-silica (Al.sub.2 O.sub.3 -SiO.sub.2) ratio from about 9:1 to about 1:1 by weight. The use of such pellets in hydraulic fracturing of subterranean formations is also described.

Abstract: A low dielectric constant ceramic substrate comprised of 90 to 98% of mullite (3Al.sub.2 O.sub.3. 2SiO.sub.2) and 10 to 2% of a sintering promotor comprised of 0.5 to 3% of magnesia (MgO) and 1.5 to 7% of calcium oxide (CaO).

Abstract: High surface area, submicron ceramic powders are synthesized by reducing an oxide in the presence of another metal (i.e., Mg, Al, Ca, and the like) and a source of carbon, nitrogen or boron to form a new oxide and a carbide, nitride (or carbonitride). or boride. The oxide phase can be leached out to leave submicron carbides, nitrides or borides. Alternatively milling of reacted powders allows intimate mixtures of uniform, fine grained ceramic powders to be prepared inexpensively. These multiple-phase composite powders can be formed into a body and densified using conventional techniques to form dense, fine-grained ceramic bodies. Alternatively, containment of unreacted powders and subsequent heating results in multiple-phase dense ceramics with unique microstures. Transformation toughening of composites is possible by adding zirconia or hafnia either before or after the powder synthesis step.

Abstract: SiC-Al.sub.2 O.sub.3 composite sintered bodies having high strength and toughness are constructed by dispersing SiC particle and SiC whisker into a matrix of Al.sub.2 Ohd 3 particles.

Abstract: SiC-Al.sub.2 O.sub.3 composite sintered bodies having high strength and toughness are constructed by dispersing SiC particles essentially inside individual of Al.sub.2 O.sub.3 grains constituting a material.

Abstract: A method is provided for producing a self-supporting ceramic composite body having a plurality of spaced apart wall members, each wall member having a bounded cross-section for defining substantially continuous, fluid passageways. The wall members generally inversely replicate in opposed directions the geometry of a positive pattern. Each of the wall members, which are axially aligned, comprises a ceramic matrix having a filler embedded therein, and is obtained by the oxdiation reaction of a parent metal to form a polycrystalline material which comprises the oxidation reaction product of the parent metal with an oxidant and, optionally, one or more metals, e.g. nonoxidized constituents of the parent metal.

Abstract: A method is provided for producing a self-supporting ceramic or ceramic composite body by oxidation of a parent metal, the self-supporting body having a graded microstructure characterized by a plurality of zones differing from each other in one or more properties. The zones in the body are attained by altering the process conditions during formation of the body such that a zone of the oxidation reaction product formed posterior to said altering has at least one property different from a zone of the oxidation reaction product formed anterior to said altering.

Abstract: Sintered, spherical composite pellets or particles comprising one or more clays as a major component and bauxite, alumina, or mixtures thereof, are described, along with the process for their manufacture. The pellets may have an alumina-silica (Al.sub.2 O.sub.3 --SiO.sub.2) ratio from about 9:1 to about 1:1 by weight. The use of such pellets in hydraulic fracturing of subterranean formations is also described.

Abstract: A ceramic consisting essentially of from 1 to 15 percent of glass and 99 to 85 percent of a mixture of particulate Al.sub.2 O.sub.3 and particulate ZrO.sub.2 is disclosed. ZrO.sub.2 is present in a sufficient amount usually from 1/4 to 6 percent base on the of the ZrO.sub.2 and Al.sub.2 O.sub.3, to strengthen the ceramic significantly, by comparison with an otherwise identical ceramic where the particulate ZrO.sub.2 is replaced either by the glass or by particulate Al.sub.2 O.sub.3. The glass constitutes a vitreous phase bonding the particulates into a dense, gas impervious structure, and can be a calcium magnesium silicate glass containing from 45 to 80 percent of SiO.sub.2, from 8 to 55 percent of CaO and MgO, and not more than 15 percent of Al.sub.2 O.sub.3.

Abstract: A refractory composition comprising a fused silica composition comprising a silica compound and a binder and for each 100 parts by weight of said fused silica composition from about 3 to 15 parts by weight of alumina-silica based hollow microspheres.

Abstract: Insulating lightweight refractory materials which are resistant to attack by molten metals, particularly molten aluminum and its alloys and compositions used to form such materials. The materials are settable compositions which comprise a mixture of ceramic fibers, wollastonite powder and aqueous colloidal silica having a solids content of about 5-25% and preferably 12-15% by weight. The weight ratio of the ceramic fibers to the wollastonite powder is 0.8-1.2:1.5-2.5, respectively. The composition optionally contains carbon fibers or metal fibers as reinforcements. The composition can be cast to form shaped products or used as a joining material or as a "face-off" material to protect an underlying article. When dried, the composition forms a material which is insulating, light-weight and resistant to high temperature and chemical attack by metals. The material can be made even more resistant to attack by a silicate and/or fluoride surface treatment.

Abstract: A method of manufacturing a molten metal-resisting ceramic fiber composition includes mixing ceramic fibers, a frit, ceramic additives, a low temperature binder, and water. The mixture is formed into a desired shape, preferably by being extruded through a die. The shaped mixture is baked at low temperature, and then is fired at high temperature. During firing, the low temperature binder is oxidized and the frit is melted so as to substantially coat the fibers and fuse them into a porous matrix.

Abstract: A process for the production of a refractory boride or silicide which comprises producing an oxygen-containing polymeric product by reacting a compound of the metallic or non-metallic element having two or more groups reactive with hydroxyl groups and a compound of boron or silicon having two or more groups reactive with hydroxyl groups with an organic compound having two or more hydroxyl groups and heating the polymeric product in an inert atmosphere to pyrolyse the polymeric product and produce a refractory boride or silicide of the metallic or non-metallic element.

Abstract: A method for producing a self-supporting ceramic composite body having a negative pattern which inversely replicates the positive pattern of a parent metal precursor having thereon a positive pattern section which is emplaced in conforming engagement with a bed of conformable filler. The parent metal precursor, which also has a non-replicating section, is melted and reacted with an oxidant to form a polycrystalline oxidation reaction product which grows primarily only from the positive pattern section of the parent metal precursor and through the filler. The molten parent metal is drawn through the growing polycrystalline material and oxidized at the interface between the oxidant and previously formed oxidation reaction product. The reaction is continued for sufficient time to at least partially embed the filler within the oxidation reaction product and form the ceramic composite body containing a negative pattern which inversely replicates the positive pattern of the parent metal precursor.

Abstract: This invention relates to the high temperature stabilization of aluminum titanate and aluminum titanate-mullite compositions by the addition of iron oxide. It has been found that iron oxide concentrations greater than 5 weight percent and as high as approximately 25 weight percent have a stabilization effect at high temperatures on aluminum titanates. The resultant ceramic body is further enhanced by the addition of from 0.1 to 5 weight percent rare earth oxide.

Abstract: A method to produce an article of commerce comprising a self-supporting ceramic body by oxidation of a molten parent metal with a vapor-phase oxidant, includes applying to a surface of the parent metal a layer at least one dopant material therein. The layer is thin relative to the thickness of the ceramic body. Upon heating the parent metal to a molten state in the presence of the oxidant, e.g., air, an oxidation reaction product is formed on the molten metal which, because of the effect of the dopant material, migrates through the growing oxidation reaction product so as to be exposed to the oxidant to form additional oxidation reaction product to and beyond the depth of the applied dopant material layer. Suitable temperature and oxidizing conditions are maintained for a time sufficient to produce a self-supporting ceramic body.

Abstract: A method of making self-supporting ceramic composite structures having filler embedded therein includes infiltrating a permeable mass of filler with polycrystalline material comprising an oxidation reaction product obtained by oxidation of a parent metal such as aluminum and optionally containing therein non-oxidized constituents of the parent metal. The structure is formed by placing a parent metal adjacent to a permeable filler and heating the assembly to melt the parent metal and provide a molten body of parent metal which is contacted with a suitable vapor-phase oxidant. Within a certain temperature region and optionally aided by one or more dopants in or on the parent metal, molten parent metal will migrate through previously formed oxidation reaction product into contact with the oxidant, causing the oxidation reaction product to grow so as to embed the adjacent filler and provide the composite structure.

Abstract: A ceramic munitions projectile, particularly useful for practice or target munitions is provided. The projectile is preferably made of zirconia which is densified by a pressureless sintering method. The projectile has sufficient toughness to withstand acceleration and torque created during projectile firing and trajectory.

Abstract: This invention relates to a cutting tool material with improved toughness behavior. The improved toughness behavior is obtained by using carefully selected reinforcing materials. The objectives of this invention are realized by simultaneously utilizing additives resulting in different toughening mechanisms. By the simultaneous utilization of different toughening additives, synergistic effects occur giving the tool excellent material properties. The tool material of the present invention comprises reinforcing whisker additives of one dimensional single crystals with preferably different diameter and aspect ratios, two dimensional single crystals with different thickness and aspect ratios, and, in combination therewith, phase transformation additives such as ZrO.sub.2.

Abstract: A lightweight refractory is disclosed which is a shaped porous body having refractory particles and aluminous short fibers bound to each other with mullite. The crtystalline structure of the refractory is chiefly composed of mullite and corundum. The mullite content is at least 12 mol % of the sum of mullite and corundum. The refractory is substantially free of free silica.

Abstract: The invention relates to a method for producing ceramic composites obtained by oxidation of an aluminum parent metal to form a polycrystalline ceramic material by providing a filler having a coating of a silicon source on at least a portion of said filler different in composition from the primary composition of said filler, said silicon source possessing intrinsic doping properties. A body of molten parent metal, adjacent a mass of the filler material, reacts with an oxidant to form an oxidation reaction product which infiltrates the adjacent mass of filler thereby forming the ceramic composite.

Abstract: Ceramic composites formed of an alumina matrix reinforced with silicon 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 1200.degree. C. This coating is less than about 100 microns thick and adequately protects the underlying composite from fracture strength degradation due to oxidation.

Abstract: The invention concerns self-supporting ceramic structures, including ceramic composite structures embedding a filler, and methods of making them. The ceramic structures comprise a polycrystalline material made by oxidation of a body of molten parent metal with an oxidant. The polycrystalline material has a first region substrate surmounted by a terminal region stratum which is integral with the first region. The terminal region stratum is harder and of denser, finer crystalline structure than the first region substrate and is formed in a reaction stage subsequent to the reaction stage in which the first region of polycrystalline material is formed. Growth of the first stage is attained by attenuating or interrupting the transport of molten parent metal to the first region under conditions which nonetheless leave or maintain therein enough oxidizable molten parent metal to form the polycrystalline material of the terminal region.

Abstract: A method for producing a self-supporting ceramic composite body which comprises preparing a polycrystalline material as the oxidation reaction product of a parent metal with a vapor-phase oxidant, comminuting the resulting material to a particulate, forming a permeable mass of said particulate as filler, and infiltrating said particulate with an oxidation reaction product of a parent metal with a vapor-phase oxidant, thereby forming said ceramic composite body.

Abstract: A ceramic substrate for densely integrated semiconductor arrays which is superior in a coefficient of thermal expansion, dielectric constant, strength of metallized bond, and mechanical strength, comprising a sintered body composed essentially of mullite crystals and a non-crystalline binder composed of SiO.sub.2, Al.sub.2 O.sub.3, and MgO, is provided.

Abstract: There is disclosed a method for producing a self-supporting ceramic body by oxidation of a molten precursor metal with a vapor-phase oxidant to form an oxidation reaction product and inducing a molten flux comprising said molten precursor metal through said oxidation reaction product. A second metal is incorporated into said molten flux during the oxidation reaction. The resulting ceramic body includes sufficient second metal such that one or more properties of said ceramic body are at least partially affected by the presence and properties of said second metal in the metallic constituent.

Abstract: Process for producing monolithic ceramic articles by sintering at temperatures from about 900.degree. C. to about 1350.degree. C. a shaped zeolite charge comprised of selected zeolites with Si/Al ratios of from about 0.7 to about 5.

Abstract: Disclosed herein is a foamable, self-setting ceramic composition which can be poured into molds or injection-molded or extruded to achieve desired shapes, and thereafter fired to produce shaped, porous ceramic articles useful as filter elements, insulation, kiln furniture, molds furnace linings or other like articles, the composition containing agents capable of developing an aluminosilicate hydrogel and capable of generating gas to produce porosity within the hydrogel bound molded shape.

Abstract: A method of synthesizing ceramic oxides using the Sol-Gel process to control particle size distribution, crystal structure and to achieve the selective incorporation of transition metals within a ceramic oxide matrix in order to produce tailored oxides with specific particle morphology and near zero expansion optical ceramics.