Abstract: Polycrystalline ceramic bodies of Si.sub.3 N.sub.4 when prepared to obtain an intergranular phase which is substantially crystalline, exhibits significantly improved mechanical strength at elevated temperatures above 1,000.degree. C. up to 1600.degree. C. over bodies having glass-containing intergranular phases.

Abstract: An article of manufacture comprising a substantially transparent high density polycrystalline yttria-based body consisting essentially of yttria and from 0.1 to 5 wt. % MgO or from 0.1 to 5 wt. % MgAl.sub.2 O.sub.4.Transparent yttria-based bodies according to this invention are particularly useful as envelopes for high pressure sodium vapor lamps.

Abstract: An article of manufacture is provided comprising a substantially transparent high density polycrystalline yttria-base body consisting essentially of yttria and from about 0.01 to 5 wt. % alumina.A method for preparing the transparent yttria doped with alumina is also provided comprising admixing alumina or a precursor thereof with yttria or a precursor thereof, drying the admixed powders, calcining the admixed powders and pressing the calcined powders into a desired shape and thereafter sintering the shaped powder for about 1/4 to six hours at a temperature above the eutectic temperature at a sufficiently low oxygen atmosphere to prevent oxidative contaminants.

Abstract: An article of manufacture is provided comprising a substantially transparent high density polycrystalline yttria-base body consisting essentially of yttria and from about 0.01 to 5 wt. % alumina.A method for preparing the transparent yttria doped with alumina is also provided comprising admixing alumina or a precursor thereof with yttria or a precursor thereof, drying the admixed powders, calcining the admixed powders and pressing the calcined powders into a desired shape and thereafter sintering the shaped powder for about 1/4 to 6 hours at a temperature above the eutectic temperature at a sufficiently low oxygen atmosphere to prevent oxidative contaminants.

Abstract: This application describes the step-wise application of heat during the sintering of a mixture of silver and cadmium oxide to give an alloy having improved characteristics. These alloys are useful as electric contacts in high electric current applications.

Abstract: This application describes a method of preparing cadmium-containing refractory metal-silver alloys by using a liquid phase sintering technique featuring a cadmium vapor over-pressure. The resultant alloys are useful as electric contacts in high electric current applications.

Abstract: This application describes the addition of an alkali metal, generally in the form of a salt thereof, to a mixture of silver and cadmium oxide, prior to the sintering step, to improve the as-sintered densities of the resultant alloy material.

Abstract: This application describes the addition of an alkali metal, generally in the form of a salt thereof, to a mixture of silver and cadmium oxide, prior to the sintering step, to improve the as-sintered densities of the resultant alloy material.

Abstract: This application describes the addition of an alkali metal, generally in the form of a salt thereof, to a mixture of silver and cadmium oxide, prior to the sintering step, to improve the as-sintered densities of the resultant alloy material.