General Electric Company

Momentive Performance Materials Gmbh

David Charles Pender

Mark Philip D'Evelyn

Charles Dominic Iacovangelo

Dong-Sil Park

Frederic F Ahlgren

Thomas Francis McNulty

Robert Arthur Giddings

Steven Alfred Tysoe

Suresh Shankarappa Vagarali

Victor Lien-Kong Lou

Frederic Francis Ahlgren

A fused quartz article, such as a muffle tube or crucible, with enhanced creep resistance. The enhanced creep resistance is the result of controlled devitrification of the fused quartz article. Controlled devitrification is achieved by coating the article with a colloidal silica slurry doped with metal cations, such as barium, strontium, and calcium. The metal cations in the slurry promote nucleation and growth of cristobalite crystals into the fused quartz at temperatures in the range from about 1000&#xb0; C. to about 1600&#xb0; C. The cristobalite has significantly higher viscosity, and therefore greater creep resistance at elevated temperatures, than fused quartz. Methods for applying a doped coating to a fused quartz article and improving the creep resistance of a fused quartz article are also disclosed.

Fused quartz article having controlled devitrification

Polycrystalline gallium nitride (GaN) characterized by having the atomic fraction of gallium ranging from between about 49% to 55%, an apparent density of between about 5.5 and 6.1 g/cm, and a Vickers hardness of above about 1 GPa. Polycrystalline GaN can be made by hot isostatic pressing (HIPing) at a temperature ranging from about 1150&#xb0; C. to 1300&#xb0; C. and a pressure ranging from between about 1 and 10 Kbar. Alternatively, polycrystalline GaN can be made by high pressure/high temperature (HP/HT) sintering at a temperature ranging from about 1200&#xb0; to 1800&#xb0; C. and a pressure ranging from about 5 to 80 Kbar.

Sintered polycrystalline gallium nitride and its production

A metal-infiltrated polycrystalline diamond composite tool comprising a plurality of diamond grains forming a continuous polycrystalline diamond matrix, a metallic phase being substantially palladium-free and contiguous to the continuous polycrystalline diamond matrix, wherein the metallic phase interpenetrates the continuous polycrystalline diamond matrix and substantially wets an outer surface of the continuous polycrystalline diamond matrix; and a working surface. The metallic phase is formed from an infiltrant and a wetting-enhancement layer disposed on the outer surfaces of the diamond particles, with both the infiltrant and wetting-enhancement layer being substantially palladium-free and comprising at least one metal from the group consisting of cobalt, iron, and nickel. The invention also includes a preform for a metal-infiltrated polycrystalline diamond composite tool, the perform comprising a container, a metallic infiltrant source, and a plurality of coated diamonds, each coated with a wetting-enhancement layer and, optionally, an activation layer, both of which are substantially palladium-free. Methods of forming the metal-infiltrated polycrystalline diamond composite tool, the preform, and the coated diamond particles used in the tool are also disclosed.

Metal-infiltrated polycrystalline diamond composite tool formed from coated diamond particles

Growing community of inventors

Schenectady, NY, United States of America

David Charles Pender