초록 ▼

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 fi

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.

대표청구항 ▼

A process for the preparation of an article of silicon nitride - bonded silicon carbide comprising: a. forming an admixture of finely divided silicon metal, and SiC grain, shaping said admixture into discrete pellets, drying said pellets, firing said dried pellets in a nitrogenous non-oxidative atmo

A process for the preparation of an article of silicon nitride - bonded silicon carbide comprising: a. forming an admixture of finely divided silicon metal, and SiC grain, shaping said admixture into discrete pellets, drying said pellets, firing said dried pellets in a nitrogenous non-oxidative atmosphere at a temperature and for a period sufficient to convert substantially all of said silicon metal to Si3N4, thereby resulting in formation of Si3N4-bonded SiC precursor material pellets having a Si3N4 content of at least 50 weight percent; b. crushing said precursor material pellets; c. mixing from 30 to 75 weight percent of said crushed precursor material with from 16 to 60 weight percent finely divided silicon metal to form a green composition; d. shaping said green composition and drying said shaped green composition; and e. firing said dried green composition in a nitrogenous non-oxidative atmosphere at a temperature and for a period sufficient to convert substantially all of said silicon metal to Si3N4.