Decomposition reactions in the SiC-Al-Y-O system during gas pressure sintering

The substantial densification, that occurred in the SiC-Al-Y-O system was e xplained in the present work by analysing possible chemical reactions and t heir dependence on initial particle associations, i.e. homogeneity of mixin g, the physical and chemical state of additives, pressurised sintering envi ronment over the reactants and temperature of sintering. Hydroxyhydrogel po wder precursors were found to be better than mechanically mixed SiC-YAG pow der and pre-forming of YAG by holding the specimens at the temperature of 1 400 degreesC for 2 h were found to be the best. Decomposition reactions wit hin the system could be controlled by using finer SIC and applying gas pres sure over the reactants. (C) 2001 Elsevier Science Ltd and Techna S.r.l. Al l rights reserved.