INTERACTION BETWEEN SIC AND TI POWDER

The interaction between SiC and Ti powder at 1073-1523 K was investiga ted employing a combination of x-ray diffraction, scanning electron mi croscopy with EDS, Auger spectroscopy, and transmission electron micro scopy. As a result of the interaction, a triple-layer reaction zone wa s formed. The most important part of the reaction zone was a mixed TiC -Ti5Si3(C) layer. Thin TiC sublayers were formed on both the inner and the outer sides of the mixed reaction layer. The reaction zone was fo und to grow by a parabolic law with the kinetic constant, k = 1.3 X 10 (-3) exp(-21800/T) cm2/s. The growth process of the SiC/Ti reaction zo ne was assumed to be controlled by diffusion of all three components o f the system: Ti, Si, and C. Thin reaction layers (<5 mum) obtained af ter short exposures at relatively low temperatures formed coatings on the SiC surface; thicker reaction layers spalled off the ceramic surfa ce. Experiments with the samples partially immersed into the metal pow der showed that interaction between SiC and Ti was very sensitive to t he environment.