Abstract: The present invention relates to a highly smooth zirconia-containing disk substrate produced by polishing a defect-free surface with fine diamond and/or alumina.

Abstract: This invention relates to a sintered silicon nitride ceramic material comprising:a) at least 80 wt % silicon nitride grains, andb) between 0.1 and 5 wt % additive grains characterized by at least one of:i)a Knoop hardness of at least 25 GPa,ii) a coefficient of thermal expansion of at least 6.times.10.sup.-6 /K, andiii) a modulus of elasticity of at least 600 GPa,wherein the maximum detectable grain size of the additive grains is no more than 4 um, as determined by a photomicrograph of a polished 75 mm.sup.2 microstructure of the silicon nitride material.

Abstract: This invention relates to tape casting a silicon carbide slip to eventually produce a silicon carbide wafer having a thickness of between 0.5 and 1 mm and a diameter of at least 150 mm, the wafer preferably having a strength of at least 30 MPa, and a porosity wherein at least 85% of the pores are no larger than 12 microns.

Abstract: This invention is a process for making crack-free silicon carbide components wherein the level of free silica in the raw batch is controlled.

Abstract: A reversible adapter designed to be disposed between the bottom of a standard mixer tap cartridge and the bottom of a standard mixer tap body chamber, said bottoms conforming to a substantially circular common design, with two inlet locations disposed symmetrically about a diameter, includes:a rigid part (10) having a transverse surface (11) flanked by a skirt (12) and including two inlet locations, two half-moon shape openings (17, 18) respectively radially inside and radially outside a half-circle,one of two elastic material seals, the first of which includes two angularly offset chambers respectively surrounding the inlet locations and the second (40) of which includes two concentric circumferential chambers disposed on radially opposite sides of this semicircle, and each of which includes, at its end axially aligned with one of the half-moons, a web (40F, 40G) defining, facing that half-moon, a cup the depth of which increases in the direction towards the other end.

Abstract: The present invention relates a ceramic igniter comprising:a) a pair of electrically conductive portions, each portion having a first end,b) a hot zone disposed between and in electrical connection with each of the first ends of the electrically conductive portions, the hot zone having an electrical path length of less than 0.5 cm, andc) an electrically non-conductive heat sink material contacting the hot zone.

Abstract: A mixer tap cartridge including a body (10) having a bush (23) with a reference axis, internal flowrate adjustment members disposed inside the body and a lever (20) cooperating with these internal members to adjust the flowrate hinged to the bush (23) about a transverse pin (24) and having an exterior part (21) projecting out of the body, the lever and the bush having complementary bearing surfaces (25, 26) conjointly defining an extreme flowrate configuration of the lever, characterised in that the bearing surface (25) of the lever is part of a projecting portion of a pin (27) sliding in a transverse hole (28) in the lever, this pin cooperating with an adjustment member (31) mobile in a housing (30) in the lever accessible from outside the cartridge.

Abstract: The present invention relates to a refractory shield for protecting a superheater tube against fluid attack comprising first and second partial-tubes (2, 8), each partial-tube having a C-shaped cross section, the C-shaped cross section defining first (3, 9) and second (4, 10) ends; wherein the ends of the partial-tubes are opposably engaged, and wherein the partial-tubes comprise means (5) for preventing radial movement of the first partial-tube relative to the second partial-tube.

Abstract: This invention relates to an acetabular cup having a substantially hemispherical ceramic concave surface comprising at least one debris reservoir thereon having a width of between 0.010 mm and 2 mm, and also to a ceramic hip joint prosthesis head whose outer surface comprises a similar debris reservoir.

Abstract: A method of producing aluminum, comprising the steps of:a) providing an aluminum reduction Hall cell for reduction of alumina in molten fluoride electrolyte containing cryolite, the cell comprising a cathode, an anode and a sidewall, the sidewall having a thickness and comprising:i) a lining consisting essentially of a material selected from the group consisting of silicon nitride, silicon carbide, and boron carbide, and having a density of at least 95% of theoretical density, and no apparent porosity, andii) an insulating layer backing the lining,b) contacting the lining with an electrolyte comprising at least 60% cryolite and having a temperature of between 650.degree. C. and 1100.degree. C.

Abstract: This invention relates to a biojoint prosthesis comprising:a) a prosthetic comprising a first component having an outer surface comprising at least 90 mol% zirconia, andb) a second component having a surface shaped to receive the outer surface of the first component,wherein the outer surface of the first component is received on the surface of the second component, andwherein a) at least a portion of the surface of the second component receiving the first component comprises a ceramic having a surface roughness of no more than 100 nm, and b) the outer surface of the first component has a surface roughness of no more than 100 nm.

Abstract: Vertical rack for supporting semiconductor wafers, the rack having either continuously upward angled arms or horizontal arms for providing near center support of the wafers.

Abstract: A process comprising the steps of:a) providing a fiber preform comprising a non-oxide ceramic fiber with at least one coating, the coating comprising a coating element selected from the group consisting of carbon, nitrogen, aluminum and titanium, and the fiber having a degradation temperature of between 1400.degree. C. and 1450.degree. C.,b) impregnating the preform with a slurry comprising silicon carbide particles and between 0.1 wt % and 3 wt % added carbonc) providing a cover mix comprising:i) an alloy comprising a metallic infiltrant and the coating element, andii) a resin,d) placing the cover mix on at least a portion of the surface of the porous silicon carbide body,e) heating the cover mix to a temperature between 1410.degree. C. and 1450.degree. C. to melt the alloy, andf) infiltrating the fiber preform with the melted alloy for a time period of between 15 minutes and 240 minutes, to produce a ceramic fiber reinforced ceramic composite.

Abstract: A method for producing a crack-free recrystallized silicon carbide body, icluding the steps of:a) providing a raw powder batch including:i) at least 40 w/o fine fraction having a particle size of less than 10 microns, the fine grain fraction including silicon carbide and fine free carbon, wherein the fine free carbon is present in an amount of at least 0.10 w/o of the raw batch, the fine free carbon having a surface area of at least 10 m.sup.2 /g,ii) at least 40 w/o coarse grain fraction having a particle size of at least 30 microns, the coarse grain fraction including silicon carbide and coarse free carbon, wherein the coarse free carbon is present in an amount of at least 0.10 w/o of the coarse grain fraction,the raw batch having a total silica content of at least 0.5 w/o,the raw batch having a total silicon carbide content of at least 96 w/o,b) forming the raw batch into a green body, andc) recrystallizing the green body to provide a recrystallized silicon carbide body having a density of between 2.

Abstract: There is provided an improved kiln furniture assembly:wherein the improvement comprises vertical posts comprising:i) a vertically disposed channel, andii) a spacer block (13a) vertically separating the upper and lower horizontal beams which extend from the same post,wherein at least a portion of the spacer block or the horizontal beam is positioned within the vertically disposed channel.

Abstract: Silicon carbide sintered bodies having controlled porosity in the range of about 2 to 12 vol %, in which the pores are generally spherical and about 50 to 500 microns in diameter, are prepared from raw batches containing a polymer fugitive. Sintered bodies in the form of mechanical seal members exhibit lower power consumption at low PV and, in addition, lower wear rates at high PV in comparison to commercially available silicon carbide seal members.

Abstract: This invention relates to polishing YTZP zirconia disk substrates with colloidal silica to achieve a surface roughness Ra of no more than 8 angstroms.

Abstract: This invention relates to a disk substrate consisting essentially of zirconia partially stabilized by a rare earth oxide, the disk substrate having a thickness of no more than 0.635 mm, a diameter of at least 10 mm, and a mean pore size of no more than 0.1 um.

Abstract: A method of heating, comprising the step of providing a line voltage of between 120V and 230 V across a ceramic igniter having a hot zone composition comprising:(a) between 50 and 80 v/o of an electrically insulating ceramic having a resistivity of at least about 10.sup.10 ohm-cm;(b) between 10 and 45 v/o of a semiconductive material having a resistivity of between about 1 and about 10.sup.8 ohm-cm;(c) between 5 and 25 v/o of a metallic conductor having a resistivity of less than about 10.sup.-2 ohm-cm; and(d) between 2.0 and 20 v/o of a resistivity-enhancing compound selected from the group consisting of metallic oxides, metallic oxynitrides, rare earth oxides, rare earth oxynitrides, and mixtures thereof.

Abstract: The invention includes a process for producing a reaction bonded silicon carbide composite reinforced with coated silicon carbide fibers which is suitable for high temperature applications. The process includes the steps of coating SiC fibers with AlN, BN or TiB.sub.2 ; treating the coated fibers with a mixture of SiC powder, water and a surfactant; preparing a slurry comprising SiC powder and water; infiltrating the coated fibers with the slurry to form a cast; drying the cast to form a green body; and reaction bonding the green body to form a dense SiC fiber reinforced reaction bonded matrix composite.The invention further includes a SiC fiber reinforced SiC composite comprising a reaction bonded SiC matrix, a SiC fiber reinforcement possessing thermal stability at high temperatures and an interface coating on the fibers having chemical and mechanical compatibility with the SiC matrix and with the SiC fibers.