METALLIZING OF SILICON-CARBIDE CERAMICS W ITH TITANIUM VAPOR

Silicon-carbide ceramic was metallized with titanium by the vapor-diff usion method, where pure titanium powder was used as a vapor source at temperatures between 973 and 1323 K for up to 296.1 ks in a dynamic v acuum atmosphere, The structure and composition of the metallized laye rs were investigated by scanning electron microscopy, electron-probe m icroanalysis, and X-ray diffraction analysis, At the initial stage of the metallization, titanium vapor reacted preferentially with the so c alled free carbon in the grain boundaries of SIC ceramics to form a ti tanium carbide, and then a metallized layer was grown laterally, formi ng the sublayer structures. This sub-layer structure was composed of f ive sub-layers; TiC (top surface), Ti3Si3 containing TiC (outer layer) , TiC containing Ti5Si3 (middle layer), Ti5Si3 (inner layer) and Ti3Si C2 (bottom layer). Growth kinetics of each sub-layer and their total t hicknesses obeyed the parabolic rate law, and the parabolic rate const ants (kp) for the total layer varied between 10(-16) m(2) . s(-1) at 1 173 K and 10(-15) m(2) s(-1) at 1323 K. The activation energy (Q(kp)) obtained for the metallized layer was 153 kJ mol(-1).