Abstract: Components for semiconductor diffusion furnaces are constructed of a high purity impervious silicon carbide or silicon nitride matrix deposited onto and within a pre-shaped fibrous matrix of silicon carbide or silicon nitride which contains sufficient nucleation aids to produce a structure having a density greater than about 85% of theoretical density. The impregnation of the matrix material into the fibrous reinforcement prevents undesired gaseous components from contaminating the atmosphere of the furnace, and the fibrous reinforcement provides strength combined with light weight.

Abstract: A method of joining two porous bodies of silicon carbide is disclosed. It entails utilizing an aqueous slip of a similar silicon carbide as was used to form the porous bodies, including the sintering aids, and a binder to initially join the porous bodies together. Then the composite structure is subjected to cold isostatic pressing to form a joint having good handling strength. Then the composite structure is subjected to pressureless sintering to form the final strong bond. Optionally, after the sintering the structure is subjected to hot isostatic pressing to further improve the joint and densify the structure. The result is a composite structure in which the joint is almost indistinguishable from the silicon carbide pieces which it joins.

Abstract: Corrosion and thermal shock resistant high silicon nitride content silicon nitride-bonded silicon carbide article, e.g., nozzle for transfer of molten metal, is prepared by combining finely divided silicon metal, silicon carbide grain with processing aids, forming the mixture into an article, and firing the article in nitrogen. Even higher silicon nitride content is obtained by crushing the article to obtain a precursor grog material, combining this grog with more finely divided silicon metal and processing aids, forming the mixture into an article and firing in nitrogen. Silicon nitride content of up to about 70 weight percent may be obtained with single mixing and firing; up to about 98 weight percent with use of nitrided precusor grog, remixing and firing. With reiteration, a silicon nitride content of essentially 100 weight percent can be approached.