CARBONITRIDING OF CLAY - RELATION BETWEEN THE WEIGHT-LOSS AND CRYSTALLINE PHASES DURING REACTION

Beta'-sialons are phases of the Si-Al-O-N system. The carbonitriding o f clays and kaolins is a preparation method. The reaction mechanism of clay carbonitriding is verified by means of the relation among crysta lline phases formed and the weight loss produced in the samples during the reaction. Two clays were previously mixed with carbon black and p ressed into pellets, flowing through N2 atmosphere, at five temperatur es within the range 1335-1427-degrees-C. The phases formed (XRD)-mulli te, SiC, beta'-sialon, and oxynitrides-were related to the weight loss measured in the pellet independently of reaction temperature and time . The beta'-sialon and the nitrogenous phases were formed from SiC and mullite. A z value decrease for beta'-sialon was observed during reac tion progression.