The United States of America As Represented by the United States

Kennecott Corporation

University of California

The Carborundum Company

Thor Technologies, Inc.

Joel D Katz

Jonathan J Kim

Rodger D Blake

Carl H McMurtry

Stuart T Schwab

Viswanathan Venkateswaran

Peter D Shalek

Thomas W Hardek

Jeffrey A Eastman

Kurt E Sickafus

George F Hurley

Method of producing hybrid metal/ceramic composites

Apparatus and method for high temperature sintering of plate-shaped articles of alumina, magnesia, silica, yttria, zirconia, and mixtures thereof using microwave radiation. An article is placed within a sintering structure located within a sintering container which is placed in a microwave cavity for heating. The rates at which heating and cooling take place is controlled.

Microwave sintering of single plate-shaped articles

Apparatus and method for producing articles of alumina and of alumina and silicon carbide in which the articles are sintered at high temperatures using microwave radiation. The articles are placed in a sintering container which is placed in a microwave cavity for heating. The rates at which heating and cooling take place is controlled.

Microwave sintering of multiple articles

A method of sintering nanocrystalline material is disclosed wherein the nanocrystalline material is microwaved to heat the material to a temperature less than about 70% of the melting point of the nanocrystalline material expressed in degrees K. This method produces sintered nanocrystalline material having a density greater than about 95% of theoretical and an average grain size not more than about 3 times the average grain size of the nanocrystalline material before sintering. Rutile TiO.sub.2 as well as various other ceramics have been prepared. Grain growth of as little as 1.67 times has resulted with densities of about 90% of theoretical.

Microwave sintering of nanophase ceramics without concomitant grain

A process for the manufacture of high purity, ultra-fine aluminum nitride powder by the carbo-nitridization of alumina. Agglomerates uniform in both size, chemical composition and porosity are formed containing a stoichiometric mixture of alumina and carbon with the addition of a small amount of catalyst. The agglomerates are furnaced in a controlled manner in a well-mixed reaction vessel to achieve a uniform and consistent level of conversion. Milling of the as-reacted agglomerates under a controlled atmosphere will produce high purity, micron sized aluminum nitride powder.

Process for the continuous production of high purity, ultra-fine,

A prealloyed metal catalyst is used to grow silicon carbide whiskers, especially in the .beta. form. Pretreating the metal particles to increase the weight percentages of carbon or silicon or both carbon and silicon allows whisker growth to begin immediately upon reaching growth temperature.

Prealloyed catalyst for growing silicon carbide whiskers

A system to prevent, retard or reverse the decomposition of silicon carbide articles during high temperature plasma sintering. Preferably, the system comprises sintering a silicon carbide refractory or ceramic green body in a closed sintering environment, such as a closed tube, with strategic placement of the plasma torch or torches, exhaust outlet and tube. As sintering proceeds, a silicon vapor pressure builds up within the tube, retarding the decomposition of the silicon carbide body. The plasma torch, exhaust outlet, and tubes are positioned so that buoyant convective flow is maximized to increase the heat transfer and energy efficiency. In another embodiment, a 'sacrificial' source of silicon carbide is placed into the sintering furnace. The silicon carbide in the sacrificial source starts to decompose before the silicon carbide refractory or ceramic article, creating a supersaturated atmosphere of silicon vapor species in the furnace. This prevents, retards or reverses the silicon carbide decomposition reactions and thus maintains the integrity of the refractory or ceramic article being sintered. Preferably, the sacrificial source is placed in a closed sintering environment along with the silicon carbide articles being sintered.

Method for preventing decomposition of silicon carbide articles during

A system to prevent, retard or reverse the decomposition of silicon carbide articles during high temperature plasma sintering. Preferably, the system comprises sintering a silicon carbide refractory or ceramic green body in a closed sintering environment, such as a covered crucible, with strategic placement of the plasma torch or torches, exhaust outlet and crucibles. As sintering proceeds, a silicon vapor pressure builds up within the crucible, retarding the decomposition of the silicon carbide body. The plasma torch, exhaust outlet, and crucibles are positioned so that buoyant convective flow is maximized to increase the heat transfer and energy efficiency. In another embodiment, a 'sacrificial' source of silicon carbide is placed into the sintering furnace. The silicon carbide in the sacrificial source starts to decompose before the silicon carbide refractory or ceramic article, creating a supersaturated atmosphere of silicon vapor species in the furnace. This prevents, retards or reverses the silicon carbide decomposition reactions and thus maintains the integrity of the refractory or ceramic article being sintered. Preferably, the sacrificial source is placed in a closed sintering environment along with the silicon carbide article being sintered.

Growing community of inventors

Los Alamos, NM, United States of America

Joel D Katz