Synthesis of chromium silicide-silicon carbide composite powders

Abstract

A special class of materials of interests to the electronic industry are the intermatallic matrix composites, containing phases such as chromium silicide and silicon carbide. Our studies address this need by investigating a low cost method for synthesizing a chromium silicide-silicon carbide composite using a chemical processing technique. The precursor used in this synthesis route is a homogeneous aqueous solution of chromium chloride and sodium methylsiliconate. This solution may be either processed in bulk or spray dried, to form an intermediate precursor powder. Subsequent thermochemical treatment was carried out at temperatures of 900, 1100 and 1300°C, in a dynamic argon gas environment. Characterization of the chromium silicide-silicon carbide composite was performed using electron microscopy and X-ray analysis. A submicron spherical composite crystalline material was obtained using spray-dried precursor powders. Irregularly shaped particles were obtained when the precursor powder was made by chemical precipitation of the bulk solution. The relative Cr-to-Si concentration distribution of the composite particles has been studied and homogeneous composite particles were produced using the spray-drying process to produce the precursor powder. Structural analysis of the composite powder indicated the presence of two chromium silicide phases, namely CrSi 2 and Cr 5Si 3. Glocuse had a significant effect in reducing the oxide impurities.