Abstract: A method of making a ceramic composite wherein a polymeric ceramic precursor or fiber reinforcement infiltrated with a polymeric ceramic precursor is associated with at least one metallic element to form a preceramic composite and the said composite is pyrolyzed by high frequency microwave radiation, preferably in the form of a beam, until the polymeric ceramic precursor is converted into a ceramic having the at least one metallic element integrally formed as part of said ceramic. The products obtained by such method comprising ceramic metal composites formed by pyrolyzing a preceramic composite to high frequency microwave radiation until the polymeric ceramic precursor is converted into a ceramic having at least one metallic element integrally formed as a part of said component.

Abstract: A method of making a ceramic composite wherein a polymeric ceramic precursor or fiber reinforcement infiltrated with a polymeric ceramic precursor is associated with at least one metallic element to form a preceramic composite and the said composite is pyrolyzed by high frequency microwave radiation, preferably in the form of a beam, until the polymeric ceramic precursor is converted into a ceramic having the at least one metallic element integrally formed as part of said ceramic.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.