Low-temperature synthesis of aluminum silicon carbide using ultrafine aluminum carbide and silicon carbide powders

The conditions for preparing alpha-aluminum silicon carbide (alpha-Al4SiC4) were examined by heating stoichiometric mixtures of ultrafine Al4C3 and SiC powders with sizes of (0.1 mu m at and below 1600 degrees C. The starting Al4C3 powder was obtained by the pyrolysis of trimethylaluminum; the starting SIC powders mere obtained by the pyrolyses of triethylsilane (3ES), tetraethylsilane (4ES), and hexamethyldisilane (6MDS). The reactivity of SIC with Al4C3 to form alpha-Al4SiC3 varies according to the kind of starting alkylsilane: 3ES > 4ES > 6MDS, The reaction of 3ES-derived SiC with Al4C3 produced alpha Al4SiC4 at temperatures as low as 1400 degrees C for 240 min, regardless of the presence of Al4C3 (trace). Only alpha-Al4SiC4 was formed at and above 1500 degrees C for 60 min; the crystal growth was appreciable.