Metallizing of Silicon-Carbide Ceramics with Titanium Vapor

Abstract

Silicon-carbide ceramic was metallized with titanium by the vapor-diffusion method, where pure titanium powder was used as a vapor source at temperatures between 973 and 1323K for up to 296.1ks in a dynamic vacuum atmosphere. The structure and composition of the metallized layers were investigated by scanning electron microscopy, electron-probe microanalysis, and X-ray diffraction analysis. At the initial stage of the metallization, titanium vapor reacted preferentially with the so called free carbon in the grain boundaries of SiC ceramics to form a titanium carbide, and then a metallized layer was grown laterally, forming the sublayer structures. This sub-layer structure was composed of five sub-layers; TiC (top surface), Ti5Si3 containing TiC (outer layer), TiC containing Ti5Si3 (middle layer), Ti5Si3 (inner layer) and Ti3SiC2 (bottom layer). Growth kinetics of each sub-layer and their total thicknesses obeyed the parabolic rate law, and the parabolic rate constants (kp) for the total layer varied between 10-16m2·s-1 at 1173K and 10-15m2·s-1 at 1323K. The activation energy (Qkp) obtained for the metallized layer was 153kJ·mol-1.