Abstract: 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.

Abstract: Low or negative thermal expansion compounds are described having a formula of A.sub.2-x.sup.3+ A.sub.y.sup.4+ M.sub.z.sup.3+ M.sub.3-y.sup.6+ P.sub.y O.sub.12. It currently is believed that y can vary from about 0 to about 2, x equals the sum of y and z and varies from about 0.1 to about 1.9. Without limitation, novel compounds satisfying the formula A.sub.2-x.sup.3+ A.sub.y.sup.4+ M.sub.z.sup.3+ M.sub.3-y.sup.6+ P.sub.y O.sub.12 where y=0 may be selected from the group consisting of Al.sub.1.5 In.sub.0.5 W.sub.3 O.sub.12, Al.sub.1.6 In.sub.0.4 W.sub.3 O.sub.12, Al.sub.1.7 In.sub.0.3 W.sub.3 O.sub.12, Al.sub.1.8 In.sub.0.2 W.sub.3 O.sub.12, YAlW.sub.3 O.sub.12, ScAlW.sub.3 O.sub.12, ScGaW.sub.3 O.sub.12, ScInW.sub.3 O.sub.12, ScHoW.sub.3 O.sub.12, ScYbMo.sub.3 O.sub.12 and ErInW.sub.3 O.sub.12. Without limitation, novel compounds satisfying the formula A.sub.2-x.sup.3+ A.sub.y.sup.4+ M.sub.z.sup.3+ M.sub.3-y.sup.6+ P.sub.y O.sub.12 where y=2 may be selected from the group consisting of Hf.sub.2 WP.sub.2 O.

Abstract: To provide a high-temperature stable transition-type alumina that does not undergo transformation into .alpha.-alumina even at high-temperature exceeding 1300.degree. C., and a method for producing the transition-type alumina.A metal aluminum block is placed on a block of .alpha.-alumina composed of Al.sub.2 O.sub.3. Portions of the .alpha.-alumina block and the metal aluminum block close to their boundary was strongly heated by contacting the flame of burning gas with the portions. Alumina and a relatively small amount of magnesium are thereby vaporized, and allowed to react with oxygen in the atmosphere, thereby obtaining a transition-type alumina that contains a small amount of magnesium in the crystal structure. The transition-type alumina obtained by this method is substantially of single crystal type, and does not undergo transformation into .alpha.-alumina even at high temperatures exceeding 1300.degree. C.

Abstract: A novel ceramic composite of a solidified body consisting of at least two crystal phases of oxides selected from metal oxides and complex metal oxides, except for the Al.sub.2 O.sub.3 /Y.sub.3 Al.sub.5 O.sub.12 combination.

Abstract: The present invention provides for microporous ceramic materials having a surface area in excess of 70 m.sup.2 /gm and an open microporous cell structure wherein the micropores have a mean width of less than 20 Angstroms and wherein said microporous structure comprises a volume of greater than about 0.03 cm.sup.3 /gm of the ceramic. The invention also provides for a preceramic composite intermediate composition comprising a mixture of a ceramic precursor and finely divided silicon carbide or silicon nitride, whose pyrolysis product in inert atmosphere or in an ammonia atmosphere at temperatures of up to less than about 1100.degree. C. gives rise to the microporous ceramics of the invention. Also provided is a process for the preparation of the microporous ceramics of the invention involving pyrolysis of the ceramic intermediate under controlled conditions of heating up to temperatures of less than 1100.degree. C. to form a microporous ceramic product.

Abstract: The present invention relates to a refractory binder that comprises a mixture of aqueous phosphate and silica sol. The silica sol has been found to gel and set in a surprisingly effective and useful way. Preferably, the refractory binder further incorporates a small amount of magnesia as an accelerator. The present invention also provides a method of binding a refractory material such, for example, as alumina, zirconia mullite or aluminium silicate by using a refractory binder according to the invention.

Abstract: A porous lithium aluminate carrier for catalyst has a spinel structure which has a mean pore diameter in the range of 40 to 1,000 angstroms and a total pore volume in the range of 0.2 to 1.5 mL/g. The porous lithium aluminate carrier can be used for supporting a catalyst compound containing a platinum group metal. The catalyst on the carrier can be favorably employed for promoting catalytic reaction of a nitrite ester and carbon monoxide to prepare a carbonate diester such as dimethyl carbonate.

Abstract: New thermally- and hydrothermally-stable .delta.-alumina compositions stabilized with an oxide of silicon, germanium, phosphorus, arsenic or a mixture thereof and methods of preparation of same are provided. Also provided are catalyst supports and catalysts made using these stabilized .delta.-alumina compositions, methods for making same, and methods for treating the exhaust gas from an internal combustion engine using such catalysts.

Abstract: A sintered aluminum nitride contains rare earth elements (RE) in amounts of from 3 to 10% by weight in terms of RE.sub.2 O.sub.3, alkaline earth elements (R) in amounts of from 0.3 to 3.0% by weight in terms of RO, and silicon atoms in an amount of from 0.3 to 1.0% by weight in terms of SiO.sub.2, the grain boundaries of AlN crystals being chiefly a YAG type crystalline phase. The sintered product is obtained by firing at a temperature as low as 1700.degree. C. or lower, has a thermal conductivity of not smaller than 60 W/m.cndot.K, loses weight in an amount of not more than 10 mg/cm.sup.2 when it is left to stand in a 4N NaOH aqueous solution maintained at 70.degree. C. for one hour, and exhibits excellent resistance against the alkalis.

Abstract: A matrix for a carbonate electrolyte including a support material and an additive constituent having a relatively low melting temperature and a relatively high coefficient of thermal expansion. The additive constituent is from 3 to 45 weight percent of the matrix and is formed from raw particles whose diameter is in a range of 0.1 .mu.m to 20 .mu.m and whose aspect ratio is in a range of 1 to 50. High energy intensive milling is used to mix the support material and additive constituent during matrix formation. Also disclosed is the use of a further additive constituent comprising an alkaline earth containing material. The further additive is mixed with the support material using high energy intensive milling.

Abstract: A low frictional ceramic material for sliding member, consists essentially of oxide of aluminum (Al) and oxide of zirconium (Zr) and contains oxide of cerium (Ce). Aluminum (Al) content is 50 to 75 wt. % in terms of alumina (Al.sub.2 O.sub.3), zirconium (Zr) content is 20 to 45 wt. % in terms of zirconia (ZrO.sub.2), and cerium (Ce) content is 3 to 20 wt. % in terms of ceria (CeO.sub.2)in said low frictional ceramic material for sliding member.Instead of oxide of aluminum (Al) and oxide of zirconium (Zr), it is capable to use a .alpha.-sialon.

Abstract: The present disclosure is directed to a method of converting the preferred hydrated alumina oxide, boehmite, into a green particle which is then sintered to form an abrasive alumina particle. The process involves dispersing boehmite in water at a slightly elevated temperature with an acidic pH, then seeding it with alumina seed particles and drying it, then crushing to desired shapes and sizes, calcining the dried precipitate and sintering the calcined material. This forms high quality alumina abrasive grains. The apparatus used for sintering incorporates an elongate hollow tube, an insulative sleeve thereabout to define an elevated temperature zone, and a microwave generator coupled through a wave guide into a microwave cavity incorporated in the tube. The particles are moved through the tube at a controlled rate to assure adequate exposure to the microwave radiation.

Abstract: A composition suitable for admixture with refractory grains to make a refractory monolithic formulation, consisting essentially of:2 to 10 parts by weight of activated alumina;0.25 to 1.0 parts by weight of an additive material which comprises at least one of an alumino-silicate-phosphate compound; a resin derived from an aldehyde and either an amine or an aromatic hydroxy compound; cellulose; polyethylene glycol(s); and methoxy polyethylene glycols;0 to 50 parts by weight of fine alumina;0 to 10 parts by weight of fine silica;0 to 1 parts by weight of a dispersant; and0 to 1 part by weight calcium aluminate cement.

Abstract: An alumina sintered body containing, as impurities, sodium oxide, potassium oxide, silicon oxide, calcium oxide, ferric oxide and titanium oxide in a total amount in the range from 100 to 10000 ppm, in which a total amount of the sodium oxide and potassium oxide based on the total amount of the impurities is not more than 4 wt. %. In the manufacture of the sintered body, its starting powder is admixed with at least an acid compound to produce metal salts by a reaction of the acid compound with metals contained in the starting powder and the resulting metal salts are removed.

Abstract: A shaped, high-strength dental ceramic prosthesis is made by pressing a molding composition including from about 1 to 50 percent by weight glass particles and from about 99 to about 50 percent by weight inorganic oxide particles at a pressure of from about 10 to about 40 MPa and a temperature of from about 1000.degree. to about 1200.degree. C. Dental prostheses prepared in accordance with the invention include crowns, bridges, inlays and onlays.

Abstract: A process for preparing a stabilized alumina wherein an aqueous slurry of a precursor boehmite alumina is admixed with an effective amount of a stabilizer such as a water-soluble salt of a polyvalent metal cation of Groups IIA and IIIB of the periodic table, the slurry containing the alumina and the stabilizer being aged at a pH of from about 3 to about 9 and a temperature greater than about 70.degree. C. for a period of time sufficient to convert the greater portion of said alumina to a colloidal sol, the colloidal sol being recovered and calcined to produce a stabilized alumina.

Abstract: An aluminous sintered product comprising 70 to 96% by weight of an alumina component and 4 to 30% by weight of additives, said additives including at least the one selected from oxides of elements of the Group 5a of periodic table and at least the one selected from oxides of metals of the iron family and oxides of manganese, titanium, calcium, magnesium, chromium and silica, and said aluminous sintered product exhibiting a volume resistivity of from 1.times.10.sup.7 to 1.times.10.sup.13 .OMEGA.-cm over a temperature range of from 25.degree. to 75.degree. C. and an absolute value of the temperature coefficient of volume resistivity of not larger than 1.8%/.degree.C. under the application of high voltages.

Abstract: An aluminum nitride substrate composed of a sintered body base material composed mainly of aluminum nitride and an aluminum oxide layer formed on the surface of the base material, wherein at least one of the base material and the aluminum oxide layer contains at least one member selected from the group consisting of single substances, carbidies, nitrides, borides and oxides of Ti, V, Nb, Mo, W, Co and Ni. This aluminum oxide layer is formed by an oxidizing treatment of the base material, and a metal conductor layer is formed on this aluminum oxide layer. This substrate has a very high allusion to the metal conductor layer.

Abstract: Plasticized inorganic powder batches comprising a cellulosic binder, water, and at least one inorganic powder exhibiting relatively high water affinity are compounded by combining the inorganic powder, prior to any contact with the water or cellulosic binder, with an organic surface treatment agent to decrease the water affinity thereof; subsequent mixing of the treated powder with the water and the cellulosic binder forms a plasticized inorganic powder batch with improved extrusion, molding, or other shaping characteristics.

Abstract: Ceramic preforms comprising monocrystalline hexagonal platelets of .alpha.-alumina, well adopted for conversion into refractory bricks or ceramic composites, are prepared by crystallizing a settled fine powder of amorphous alumina, transition alumina or alumina hydrate, advantageously in the presence of a fluoro-compound flux, into a coherent mass of such hexagonal platelets of .alpha.-alumina.

Abstract: The disclosure refers to the art of remarkably increasing the hardness of alumina materials, such as alumina abrasives, alumina ceramics or aluminum oxide single crystal (sapphire), containing aluminum oxide (Al.sub.2 O.sub.3) as the main component, or the hardness of products using the same.The alumina material is partially or wholly hardened to have a micro-Vickers hardness of no less than 2600 kgf/mm2 (under a test load of 300.times.9.807 mN) by inclusion of an oxide or fluoride additive which is solid-soluble in aluminum oxide. Preferable examples of the additive include TiO.sub.2 and/or Y.sub.2 O.sub.3.

Abstract: The dielectric ceramic composition for use with a laminated capacitor to be used in a high frequency region improves in costs of manufacturing by lowering the temperature of calcination as relatively high as from ca. 1,200.degree. C. to 1,500.degree. C. required for conventional ones and by reducing the expensive costs of electricity required otherwise by the manufacture of conventional ones. The dielectric ceramic composition contains a magnesium silicate-zinc component, an alumina component and a strontium titanate component, as represented by formula:Z(Mg.sub.a Zn.sub.(1-a)).sub.x SiO.sub.x+2 --YAl.sub.2 O.sub.3 --ZSrTiO.sub.3wherein a is equal to or larger than 0.1 and equal to or smaller than 0.8; and x is equal to or larger than 0.67 and equal to or smaller than 1.5; and wherein a molar ratio (%) of the magnesium silicate-zinc component, as represented by (Mg.sub.a Zn.sub.(1-a)).sub.x SiO.sub.x+2, to the alumina component, as represented by Al.sub.2 O.sub.

Abstract: The present disclosure is directed to a method of converting the preferred hydrated alumina oxide, boehmite, into a green particle which is then sintered to form an abrasive alumina particle. The process involves dispersing boehmite in water at a slightly elevated temperature with an acidic pH, then seeding it with alumina seed particles and drying it, then crushing to desired shapes and sizes, calcining the dried precipitate and sintering the calcined. This forms a high quality alumina abrasive grains. The apparatus used for sintering incorporates an elongate hollow tube, an insulative sleeve thereabout to define an elevated temperature zone, and a microwave generator coupled through a wave guide into a microwave cavity incorporated in the tube. The particles are moved through the tube at a controlled rate to assure adequate exposure to the microwave radiation.

Abstract: Light-transmissive ceramics are disclosed composed of a plurality of oxides each having a negative standard Gibbs energy of formation (.DELTA.Gf.sup.0) with an absolute value greater than 1581.9 KJ/mol. The light-transmissive ceramics are produced by subjecting the oxides to hot isostatic pressing at a high temperature under a high pressure after they have been subjected to primary sintering. The light-transmissive ceramics of Al.sub.2 O.sub.3 /La.sub.2 O.sub.3 are of a composite structure with particles of La.sub.2 O.sub.3 being present between particles of Al.sub.2 O.sub.3, rather than Al.sub.2 O.sub.3 and La.sub.2 O.sub.3 forming a solid solution. In the composite structure, the particles of La.sub.2 O.sub.3 have sizes that are 1/3 to 1/30 of the particles of Al.sub.2 O.sub.3. Maximum size particles of Al.sub.2 O.sub.3 have a longer axis of 30 .mu.m or less and a shorter axis of 20 .mu.m or less, and maximum size particles of La.sub.2 O.sub.3 or the like have a longer axis of 10 .mu.

Abstract: Method for making alpha alumina-based abrasive grain from a dispersion comprising boehmite. The abrasive grain can be incorporated into abrasive products such as coated abrasives, bonded abrasives, and non-woven abrasives.

Abstract: An aluminum nitride ceramic having enhanced properties suitable for electronic packaging applications can be prepared from a synergistic aluminum nitride powder/sintering aid mixture, in which the sintering aid is formulated to provide a resultant desirable second phase within the sintered body. The aluminum nitride powder/sintering aid mixture can be formed into green sheet-metal laminates and sintered at low temperature to yield high density, high electrical resistivity, and high thermal conductivity metal ceramic sintered bodies with low camber.

Abstract: A synthetic clay for ceramics is formed of 30-65 wt % of amorphous silica, 30-65 wt % of alumina trihydrate, and 2-20 wt % of at least one element selected from a group consisting of sepiolite, palygorskite, and bentonite. The clay may have a slurry form, partially dehydrated form, or mass or dry powder. The synthetic clay is comparable or even superior to natural clay in plasticity, water retentivity and capability of forming water film. The synthetic lay is useful for ceramic industry or pottery.

Abstract: An alumina-based sintered material for ceramic heater having a resistance heater embedded in its ceramic material. With the total amount of Al.sub.2 O.sub.3, SiO.sub.2, MgO and CaO being 100 wt %, the sintered material contains 91 to 97 wt % of Al.sub.2 O.sub.3, 1 to 8 wt % of SiO.sub.2, 0.2 to 1.2 wt % of MgO and 0.2 to 1.2 wt % of CaO, the total amount of MgO and CaO being 0.4 to 1.8 wt %, whereas, for the total amount of Al.sub.2 O.sub.3, MgO and CaO of 100 wt %, 0.1 to 15 wt % of (a) at least one of rare earth elements and groups IVa excluding Ti, Va and VIa of the Periodic Table are contained in the sintered material. In place of (a), 0.2 wt % or less of other elements (Na, K, Fe, Ti etc.) may also be contained in an amount not more than 0.2 wt %, calculated in terms of oxides.

Abstract: An optically translucent polycrystalline alumina sintered body consists essentially of alumina, magnesia, terbia and, optionally, yttria. The magnesia is present in an amount of about 0.020 wgt. percent and the terbia is present in an amount of from about 0.005 to 0.060 wgt. percent. The yttria is present in an amount up to about 0.035 wgt. percent.

Abstract: This invention relates to a Hall-Heroult cell for aluminum production comprising a cryolite-resistant liner comprising:i) between 75 weight percent wt % and 95 wt % alumina-silica refractory grain, andii) between 1 wt % and 10 wt % of a sealant selected from the group consisting of feldspar and nepheline.

Abstract: A .beta.-alumina electrocast refractory formed of a composition of 91-95 wt. % of Al.sub.2 O.sub.3, 2.0 wt. % or less of K.sub.2 O, 4.0-7.0 wt. % of Na.sub.2 O and K.sub.2 O in total, 0.15-2.0 wt. % of BaO, SrO and CaO in total, and 0.1 wt. % or less of Fe.sub.2 O.sub.3 and TiO.sub.2 in total.

Abstract: The invention is directed to a non-vapor phase process for forming a metal/ceramic composite containing a relatively inert metal such as silver, copper, or nickel by the reaction of a reactive metal or metal alloy containing the inert metal, and a sacrificial ceramic preform. The resulting metal/ceramic composite is essentially the same shape and dimensions as the sacrificial ceramic preform, and exhibits improved physical and mechanical properties, including improved corrosion and wear resistance.

Abstract: Alumina composites of unusually high hardness and toughness are formed by combining alumina and diamond in nanocrystalline form, followed by sintering at high pressure.

Abstract: A method of treating spent potliner material from aluminum reduction cells is disclosed. The spent potliner material is introduced into a sulfuric acid digester to produce a gas component including hydrogen fluoride and hydrogen cyanide and a slurry component including carbon, silica, alumina, sodium sulfate, iron, calcium and magnesium. The gas component is recovered and heated an effective amount to eliminate hydrogen cyanide and produce a remaining gas component including CO.sub.2, H.sub.2 O, nitrogen oxides and HF. The remaining gas component is directed through a water scrubber to form hydrofluoric acid, and the hydrofluoric acid is admixed with aluminum hydroxide to create aluminum fluoride. The slurry component is rinsed with water to separate a first solid fraction containing carbon, alumina and silica from a second liquid faction. The pH of the liquid fraction is adjusted to first create and separate aluminum hydroxide and then to separate sodium sulfate.

Abstract: Method of lubricating a rubbed surface with a gaseous phase lubricant including a monomer constituent dispersed in a carrier fluid, where the monomer constituent is capable of forming in situ a polymer film directly on rubbing surfaces but is not polymerized in the carrier fluid, such that wear and friction of the rubbed surface are effectively reduced.

Abstract: Novel aluminum phosphates, in particular amorphous aluminum phosphate powders having a BET specific surface no greater than 25 m.sup.2 /g, well suited as binders/hardeners or for the production of ceramic shaped articles, are prepared by reacting at least one aluminum compound, e.g., an aluminum oxide, hydroxide or oxyhydroxide, with phosphoric acid or an aluminum phosphate, e.g., an acid aluminum orthophosphate, in a liquid reaction medium devoid of inorganic acid anions other than of phosphoric acid, and then spray- or freeze-drying the suspension thus obtained.

Abstract: A beta-alumina solid electrolyte for use in a sodium-sulfur battery is composed of beta-alumina crystals having a degree of orientation toward the C axis thereof, of 0.2-0.4 and an aspect ratio of 4.0 or less. The beta-alumina solid electrolyte is composed of the beta-alumina crystals having a degree of orientation toward the C axis thereof, of 0.2-0.4 and has such a particle diameter distribution that the average particle diameter is 3 .mu.m or less, the proportion of the particles having a particle diameter of 5 .mu.m or less is 90% or more, and the maximum particle diameter is 300 .mu.m or less. A process for producing a beta-alumina solid electrolyte using an alumina source material, a magnesium source material and a sodium source material, uses a magnesium-aluminum spinel as the magnesium source material and subjects all materials to mixing, granulation, molding and firing to obtain a beta-alumina solid electrolyte without subjecting the materials to calcination.

Abstract: Gamma-aluminum oxynitride ground powders, white in color and well suited for conversion into optically transparent ceramic shaped articles, 100% of the particles of which being less than 10 .mu.m in size and exhibiting a transmittance of at least 8%, are prepared by grinding particulate gamma-aluminum oxynitride agglomerates having a porosity of greater than 75%, such agglomerates themselves being produced by interreacting dry powdery admixture of aluminum nitride, alpha-alumina, and an alumina of high specific surface area or precursor thereof.

Abstract: A solid state method of converting a polycrystalline ceramic body to a single crystal body includes the steps of doping the polycrystalline ceramic material with a conversion-enhancing dopant and then heating the polycrystalline body at a selected temperature for a selected time sufficient to convert the polycrystalline body to a single crystal. The selected temperature is less than the melting temperature of the polycrystalline material and greater than about one-half the melting temperature of the material. In the conversion of polycrystalline alumina to single crystal alumina (sapphire), examples of conversion-enhancing dopants include cations having a +3 valence, such as chromium, gallium, and titanium.

Abstract: A ceramic which is thermal shock resistant and which is a sintered, homogeneous mixture of first and second ceramic powders, including a first ceramic powder which is based on at least one tetravalent oxide selected from the group including zirconium dioxide, hafnium dioxide, and thorium dioxide, and which is further composed of at least one stabilizer oxide selected from the group including oxides effective to stabilize the at least one tetravalent oxide; and a second ceramic powder which is based on at least one tetravalent oxide selected from the group including zirconium dioxide, hafnium dioxide, and thorium dioxide, which contains from 0 to 2.5 mole % of at least one stabilizer oxide based on that molar amount of Y.sub.2 O.sub.

Abstract: An optically transparent polycrystalline alumina sintered body consists essentially of alumina, magnesia, yttria and zirconia. The magnesia is present in an amount of about 0.020 wgt. percent, the yttria is present in an amount of about 0.035 wgt. percent, and the zirconia is present in an amount of about 0.018 wgt. percent. An arc tube for a high pressure sodium lamp made from this composition has greatly increased resistance to sodium loss and concomitant outer jacket darkening, whereby the effective amount of lumen output is increased.

Abstract: Composites in the form of a three-dimensional framework or skeleton of ceic particles are formed by a low cost, low temperature sintering process which decomposes a pre-ceramic inorganic or organic precursor. Upon heating, preferably in air, the precursor decomposes to form a ceramic phase in the form of necks between the individual ceramic particles. The properties of the resulting porous ceramic bodies can be modified, such as toughened by impregnation with monomers, oligomers or polymers which are polymerized or cured in situ. Such composites find use as cosmetic products or protheses for humans and animals, such as dental restoratives and bone implants. Methods of fabrication are disclosed which include the use of a pre-ceramic polymer as a binder for the ceramic particles which forms the necks of material between the individual ceramic particles upon firing.

Abstract: An alumina composition, an alumina molded article, prepared from the alumina composition, an alumina ceramic prepared by sintering the alumina molded article, and a process for producing the ceramic; the alumina composition comprising .alpha.-alumina particles having a ratio of the shortest diameter to the longest diameter of from 0.3 to 1; and a size distribution of not more than 5, as expressed in terms of a D.sub.90 /D.sub.10 ratio, wherein D.sub.10 and D.sub.90 represent a cumulative 10% diameter and a cumulative 90% diameter, respectively, of a cumulative distribution depicted from the small diameter side, or comprising .alpha.-alumina particles having a polyhedral shape; a D/H ratio of from 0.5 to 3.0, wherein D represents a maximum particle diameter parallel to a hexagonal lattice plane of a hexagonal close-packed lattice of .alpha.-alumina, and H represents a particle diameter perpendicular to the lattice plane; and a size distribution of not more than 5, as expressed in terms of a D.sub.90 /D.sub.

Abstract: A composite ceramic wafer including a beta silicon carbide layer. The composite ceramic wafer is useful for making thin film magnetic heads.

Abstract: The present invention relates to novel alumina-based ceramic composition containing a compound capable of forming a spinel-type aluminate phase detectable by x-ray diffraction, the composition having particular advantage for use as a water faucet seal.

Abstract: A method for improving the properties of ceramic green bodies is provided. In particular, ceramic green bodies having improved green strength are provided. Incorporating certain acid-containing polymers as binders at a level of at least about 1 to about 15, preferably at least about 3 to about 10 percent by weight based on the weight of ceramic particles improves the green strength of the resulting ceramic green bodies.

Abstract: A ceramic composition for sintering into sliding parts contains:at least 90% by weight alumina,1.7% by weight to 2% by weight Mn.sub.3 O.sub.4,0.8% by weight to 1% by weight TiO.sub.2,0.5% by weight to 1.5% by weight SiO.sub.2,0.6% by weight to 1.2% by weight CoO,not more than 1% by weight MgO,not more than 0.4% by weight Fe.sub.2 O.sub.3,the remainder, up to 0.5% in total, comprising impurities.After sintering, this composition produces sliding parts containing manganese aluminate and/or cobalt aluminate phases.

Abstract: Non-magnetic ceramics for recording/reproducing heads comprising an alumina and any one of a compound selected from silicon carbide, boron carbide, zirconium carbide, titanium oxide, aluminum boride or zirconium boride, said ceramics having a Young's modulus of not smaller than 370 Gpa and a surface coarseness Ra after milling of not larger than 100 nm, and a method of producing the same.

Abstract: A method of making an alpha alumina-based ceramic abrasive grain comprising, on a theoretical oxide basis, Al.sub.2 O.sub.3, Fe.sub.2 O.sub.3, and SiO.sub.2. The abrasive grain has a surface roughness height of greater than about 200 nanometers and a density of greater than about 3.50 g/cm.sup.3. Preferably, the alpha alumina-based ceramic abrasive grain has alpha alumina crystallites having an average crystallite size of less than about 0.5 micrometer (more preferably, less than about 0.3 micrometer). The presence of the SiO.sub.2 in combination with Fe.sub.2 O.sub.3 increases the amount of transgranular fracture of the abrasive grain, reduces the alpha alumina crystallite growth during sintering of the abrasive grain, dilates at least one of the unit cell dimensions of the abrasive grain, and generally improves the grinding performance of the abrasive grain.

Abstract: Methods for making abrasive articles (e.g., coated abrasives, bonded wheels, and three dimensional, low density abrasives) comprising crystalline ceramic, alpha alumina-based abrasive grain.