1996 Volume 45 Issue 4 Pages 357-361
Microwave digestion techniques were examined to determine impurities in silicon nitride and silicon carbide powders. Each sample was decomposed within two hours by the following procedures. A 0.5 g sample of silicon nitride powder and mixture of 9 ml of hydrofluoric acid and 3 ml of nitric acid were put into a Teflon pressure vessel with a polypropylene jacket, and then decomposed by heating in a microwave oven. Similarly an approximately 0.5 g sample of silicon carbide (β-SiC) powder was decomposed with a mixture of 3 ml of hydrofluoric acid, 3 ml of nitric acid and 6 ml of sulfuric acid by heating in a microwave oven. α-SiC powder, however did not dissolve, while β-SiC powder did. The proposed methods were applied to JCRM-R-005 and some commercial powders of silicon nitride and silicon carbide, and the impurities were determined by ICP-AES and AAS. Analytical results were compared with the results of conventional acid pressure decomposition method.
