INTERACTION BETWEEN SIC AND TI POWDER

The interaction between SiC and Ti powder at 1073-1523 K was investigated employing a combination of x-ray diffraction, scanning electron microscopy with EDS, Auger spectroscopy, and transmission electron microscopy. As a result of the interaction, a triple-layer reaction zone was 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 found 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 zone was assumed to be controlled by diffusion of all three components of the system: Ti, Si, and C. Thin reaction layers (<5 mum) obtained after short exposures at relatively low temperatures formed coatings on the SiC surface; thicker reaction layers spalled off the ceramic surface. Experiments with the samples partially immersed into the metal powder showed that interaction between SiC and Ti was very sensitive to the environment.