Gte Laboratories Incorporated

Osram Sylvania Inc.

Valenite, Inc.

John Walsh

George C Wei

Walter Peter Lapatovich

Jerry Martin Kramer

Romano G Pappalardo

An arc tube for an electrodeless metal halide discharge lamp has an arc chamber fabricated from a material selected from the group consisting of magnesia-doped polycrystalline alumina, silicon dioxide doped polycrystalline alumina and monocrystalline alumina. The arc chamber is tubular and has at least one end and has a given outside diameter. At least one end cap closes the at least one end of the arc chamber, the end cap being formed from magnesia-doped polycrystalline alumina and comprising a substantially cup-shaped member having an inside diameter which is sealed to the outside diameter of the arc chamber by a shrink-fit.

Arc tube for electrodeless lamp

An arc tube for an electrodeless metal halide discharge lamp has an arc chamber fabricated from a material selected from the group consisting of magnesia-doped polycrystalline alumina, silicon dioxide doped polycrystalline alumina and mono-crystalline alumina. The arc chamber is tubular and has at least one end and has a given outside diameter. At least one end cap closes the at least one end of the arc chamber, the end cap being formed from magnesia-doped polycrystalline alumina and comprising a substantially cup-shaped member having an inside diameter which is sealed to the outside diameter of the arc chamber by a shrink-fit.

A method of making a continuously sintered ceramic body. A ceramic green body is prepared from a powder mixture comprising alumina, TiC (or Ti(C,N)), in a weight ratio of alumina to TiC of about 40:60-95:5, a densification aid, and TiO.sub.2 in a weight ratio of TiO.sub.2 to alumina plus TiC of 0:100 to about 2:98. The green body is prefired, then continuously rapid sintered by heating in a belt furnace in Ar or N.sub.2 containing up to 8 w/o H.sub.2 to about 1800.degree.-1920.degree. C. for a time sufficient to achieve a density of at least about 4.12 g/cc. The rate of travel of the prefired body through the belt furnace provides a heating rate above about 800.degree. C. between about 225.degree. C./min. and the rate at which the body experiences thermal shock. Carbon monoxide is intoduced to the atmosphere during the sintering step only after the temperature exceeds about 1400.degree. C. The amount of CO introduced is selected to inhibit reaction between the alumina and TiC. The CO may be introduced by placing a mass of graphite in the furnace such that CO is released only above 1400.degree. C. The body may be prepared from a homogeneous slurry, and the green body may be presintered, isopressed, and sintered or sintered and hot-isostatic-pressed.

Continuous process for producing alumina-titanium carbide composites

A method of making a sintered ceramic body for applications such as wear resistant parts and cutting tools. A green body is prepared from a powder mixture including alumina, TiC or (Ti(C,N)), a densification aid, and TiO.sub.2. The weight ratio of alumina to TiC in the body is about 40:60 to about 95:5; that of TiO.sub.2 to alumina plus TiC is 0:100 to about 2:98. The green body is rapid sintered by heating in a sintering atmosphere to about 1800.degree.-1920.degree. C. for a time sufficient to achieve a density of at least about 4.20 g/cc. The heating rate above about 800.degree. C. is between about 120.degree. C./min and the rate at which the green body experiences thermal shock. The sintering atmosphere is Ar-H.sub.2 or N.sub.2 -H.sub.2 in a molar ratio of Ar or N.sub.2 to H.sub.2 of about 92:8 to 100:0. Carbon monoxide is introduced to the sintering atmosphere only after the sintering temperature exceeds about 1400.degree. C. The amount of CO introduced is selected to inhibit reaction between the alumina and TiC. The CO may be introduced by placing a mass of graphite including adsorbed oxygen and water in the furnace at initiation of sintering such that the mass releases CO only after the sintering temperature exceeds 1400.degree. C. The body may be prepared from a homogeneous slurry, which is dried and shaped to form a green body having a density of at least about 30% of theoretical. The green body may be presintered, isopressed to collapse any cracks, macroscopic pores, or voids, and sintered or sintered and hot-isostatic-pressed.

Rapid sintering method for producing alumina-titanium carbide composites

A thermal shock apparatus comprises a hot gas stream impinging means, a hot gas stream impinging control means, a positioning means for the hot gas stream impinging means, and a sample holding means. A sample is subjected to an essentially instantaneous impingement of a hot gas stream upon a predetermined area of the sample when a heat gun is moved past heat deflection foils and positioned above the sample causing a thermal shock within the sample.

Thermal shock test apparatus and the method of testing

Yellow emitting fluorescent lamp phosphors comprise cerium and manganese activated calcium-strontium fluoroapatite compositions represented by the approximate formula

Process for producing a yellow emitting phosphor

A luminescent phosphor composition having enhanced luminescent decay lifetime consists essentially of a non-stoichiometric cerium and manganese coactivated alkaline earth orthophosphate represented by the formula

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Milford, MA, United States of America

John Walsh