Abstract: A combination of a cup shaped or cylindrically shaped grinding wheel and a mounting means for such a wheel.

Abstract: Butt joints between materials having different coefficients of thermal expansion are prepared having a reduced probability of failure of stress facture. This is accomplished by narrowing/tapering the material having the lower coefficient of thermal expansion in a direction away from the joint interface and not joining the narrow-tapered surface to the material having the higher coefficient of thermal expansion.

Abstract: Strong and durable alpha alumina ultrafiltration membranes with effective separating layers having effective pore diameters less than about 50 nm, and particularly at almost any point within the range of about 10 to about 50 nm, can be produced by seeding boehmite sols with appropriate seeds, such as very fine alpha alumina with a specific surface area of more than 100 sq. m. per g, gelling a thin layer of the sol by contact with a microfilter support, drying the gel, followed by controlled heating of the coated support both to convert the boehmite to alpha alumina and to simultaneously control the effective pore diameter of the resultant membrane.

Abstract: Useful ceramic bodies can be made by mixing zirconia powder with seeded alumina gel, drying, and firing at a high enough temperature to convert the alumina in the gel to microcrystalline alpha alumina. Abrasive grits made in this way, with a zirconia content between 15 and 30 weight percent and at least half the zirconia in the tetragonal crystal form are particularly valuable for use in grinding wheels for snagging steels.

Abstract: Filter for hot gases, comprising a mass of grains formed of a ceramic having a high melting temperature and bonded together at contact point by molten power of the same ceramic.

Abstract: An improved silicon nitride bonded silicon carbide refractory is disclosed. The improvement results from coating the silicon carbide grains with, or introducing into the bond during the mix preparation step, zirconium orthosulfate. The resulting product has higher moduli of rupture and elasticity as compared to prior art compositions where zirconia is introduced into the bond.

Abstract: The reliability of silicon nitride bodies for use in bearings can be greatly improved by control of microstructural flaws which produce bright specular reflections when metallographically prepared surfaces of the composites are examined microscopically in low angle incident light, dark field reflected light, or reflected polarized light viewed through a crossed polarizing analyzer. The population of such flaws can be controlled by modestly increasing the normal amount of intergranular phase and longer than normal milling times before sintering. Size classification of the powder before compression also improves the performance of the body.The fatigue cycles to failure of ten percent of the silicon nitride surfaces tested at 6.9 GPa contact stress in accelerated bearing failure ASTM Test STP 771 (L.sub.

Abstract: An oxygen sensing package includes a solid electrolyte sensor and a silicon carbide heating element arranged so as to surround the solid electrolyte and radiate heat to it from convex surfaces.

Abstract: A method of joining two pre-sintered pieces of silicon carbide is disclosed. It entails polishing the surfaces to be joined to a mirror-finish, fitting the polished surfaces together to form a composite structure, and then subjecting the composite structure to hot isostatic pressing under conditions which are sufficient to form a joint which is essentially indistinguishable from the original silicon carbide pieces.

Abstract: A method of joining two porous bodies of silicon carbide is disclosed. It entails utilizing an aqueous slip of a similar silicon carbide as was used to form the porous bodies, including the sintering aids, and a binder to initially join the porous bodies together. Then the composite structure is subjected to cold isostatic pressing to form a joint having good handling strength. Then the composite structure is subjected to pressureless sintering to form the final strong bond. Optionally, after the sintering the structure is subjected to hot isostatic pressing to further improve the joint and densify the structure. The result is a composite structure in which the joint is almost indistinguishable from the silicon carbide pieces which it joins.

Abstract: A novel process for rapid solidification of ceramic melts combines certain features of cooling by atomization and by contact with chilling surfaces. The material to be solidified is divided into fine liquid dropletes that are propelled by a rapid flow of gas toward a rapidly moving chill surface, striking the surface with sufficient velocity to flatten each drop into a flat flake like shape. Apparatus for the process is also disclosed. The process is particularly applicable to making very fine grained, or even amorphous, ceramic materials that can be powdered and then sintered into strong, tough ceramic structures.

Abstract: The grinding performance of organic bonded abrasive bodies whose abrasive portion is wholly or partially composed of aluminous abrasive grits is significantly improved by providing a magnesium oxide-rich or manganese oxide-rich coating on furfural-wetted grits just prior to addition of resin and filler in the mixing process.

Abstract: A two zoned grinding wheel is disclosed having a lower section or zone composed of bonded abrasive grain and an upper zone or section made up of bonded particles of a material that is softer than the abrasive grain and therefore less abrasive. The wheel is especially suitable for being held in clamps or a chuck when being used, with the clamps or chuck contacting the wheel on the upper less abrasive section thus greatly reducing wear on said clamp or chuck.

Abstract: A grinding device is disclosed which is particularly suited for grinding railroad tracks. The device is made up of back plate attached to a grinding wheel which is in turn attached to a grinding machine by way of a spindle. The surface of the plate which makes contact with the grinding wheel contains at least two lugs and at least two bolt holes pass through the plate. The lugs on the plate mate with correspondingly shaped depressions or indentations in the side surface of the wheel which contacts the plate and threaded nuts molded in the wheel line up with the bolt holes in the plates and bolts passed therethrough keep the two parts together.

Abstract: A product and process for reconditioning abrasive stones used to sharpen metal tools such as woodworking tools. The product is a slab made up of abrasive grain bond with an organic polymer.

Abstract: The flexural strength and stress rupture life of isostatically hot pressed silicon nitride containing between 1 and 12 weight percent of rare earth oxide and not more than 0.5 weight percent alumina is substantially increased by treating green bodies in flowing nitrogen at a temperature between 1000.degree. and 1500.degree. C. before degassing for the isostatic hot pressing. The iron content of the bodies is also reduced by this heat treatment, and this is believed to eliminate sources of fracture failure. Silicon nitride bodies with a flexural strength in excess of 525 MPa at 1370.degree. C. and with stress rupture lives reliably in excess of 200 hours at 300 MPa stress at 1370.degree. C. can be prepared in this way. The strain rates of silicon nitride under high temperature stress can also be reduced.

Abstract: A grinding wheel is disclosed which is made up of sintered aluminous abrasive and a vitrified bond, the vitrified bond being a frit. A large portion of the sintered aluminous abrasive may be replaced by a non-sintered abrasive and the bond may include fillers and/or grinding aids.

Abstract: Tough composites of polymer derived silicon carbide fibers in silicon nitride matrices, especially reaction bonded silicon nitride matrices, can be made by precoating the fibers with pyrolytic carbon and controlling the nitridation or other process which forms the silicon nitride matrix so that a thickness of at least 5 nanometers of carbon remains in the composite after it is formed. Failure of such composites is non-catastrophic. Alternatively, with at least some specific types of polymer derived silicon carbide fibers, composites with non-catastrophic failure can be made by controlling the nitriding conditions to produce an essentially void space around the fibers in the final composites. As still another alternative, the space around the fibers may be partially filled with silicon nitride whiskers generated during the nitridation process.

Abstract: Bag for receiving a gas stream containing solid particulate and undesirable gaseous components, consisting of inner and outer tubular porous walls arranged coextensively to define a space between them, which space is divided at discrete intervals into compartments containing solid particles of chemical to treat the gaseous components.

Abstract: Very tough composites of silicon carbide fibers in silicon nitride matrices, especially reaction bonded silicon nitride matrices, can be made by precoating the fibers with pyrolytic carbon and controlling the nitridation or other process which forms the silicon nitride matrix so that a thickness of at least 5 nanometers of carbon remains in the composite after it is formed. Failure of such composites is non-catastrophic.