Phase equilibria in the system Si sub 3 B sub 4 -SiO sub 2 -BeO-Be sub 3 N sub 2

• Published in: Journal of the American Ceramic Society 1975-01, Vol.58 (9-10), p.377-380
• Main Authors: Huseby, Irvin C, Lukas, Hans L
• Format: Article
• Language: English
• ISSN: 0002-7820

The 1780 degrees C isothermal section of the reciprocal quasi-ternary system Si sub 3 N sub 4 -SiO sub 2 -BeO-Be sub 3 N sub 2 was studied by the X-ray analysis of hot-pressed samples. The equilibrium relations shown involve previously known compounds and 8 new ones: Be sub 6 Si sub 3 N sub 8, Be sub 11 Si sub 5 N sub 14, Be sub 5 Si sub 2 N sub 6, Be sub 9 Si sub 3 N sub 10, Be sub 8 SiO sub 4 N sub 4, Be sub 6 O sub 3 N sub 2, Be sub 8 O sub 5 N sub 2, and Be sub 9 O sub 6 N sub 2. Large solid solubility occurs in beta-Si sub 3 N sub 4, BeSiN sub 2, Be sub 9 Si sub 3 N sub 10, Be sub 4 SiN sub 4, and beta-Be sub 3 N sub 2. Solid solubility in beta-Si sub 3 N sub 4 extends toward Be sub 2 SiO sub 4 and decreases with increasing temp. from 19 mol% at 1770 degrees C to 11.5 mol% Be sub 2 SiO sub 4 at 1880 degrees. A 4-phase isotherm, liquid plus beta-Si sub 3 N sub 4 (ss) reversibly yields Si sub 2 ON sub 2 plus BeO, exists at 1770 degrees.