Addition of iron (III) oxide in the alkali fusion of silicon carbide prepared by chemical vapor deposition for a highly precise determination of total silicon

Abstract

Because SiC prepared by chemical vapor deposition(CVD) has a high density, high strength and oxidation resistance, its pulverizing with alumina or tungsten carbide mortar prior to alkali fusion causes severe contamination. On the contrary, the alkali fusion of coarse or crushed SiC is very vigorous, resulting in loss by bumping. A crushed sample of 0.25 g can be fused under a gentle condition with 0.1 g of iron(III) oxide and 3 g of a mixture(6 : 1) of sodium carbonate and boric acid. Alter a cake was dissolved in hydrochloric acid, the total silicon was determined with agglomerated mass plus inductively coupled plasma atomic emission spectrometry (ICP-AES). Through this method, it was possible to determine with high precision the total silicon content of SiC. The proposed method enables one to determine the relation between the synthetic condition and the composition of the main component. © 2001 The Japan Society for Analytical Chemistry.