Phase assemblages of (Ca,Mg)-α-sialon ceramics derived from an α-sialon powder prepared by SHS

(Ca,Mg)-alpha-sialon powders were previously [J. Mater. Chem. 12 (2002) 1199] prepared by Self-propagating high-temperature synthesis (SHS) technology using slag as a raw material (abbreviated as Slag alpha-sialon powder). In this study, phase assemblages of the Slag alpha-sialon samples hot-pressed from 1450 to 1700 degreesC were investigated. Results indicated that a-sialon was the main crystalline phase in the whole sintering process, however, a small amount of beta-sialon appeared in the samples sintered at 1500 degreesC and above. In addition, the SHS technique was also used to prepare a-sialon powders using chemical agents as raw materials (named Chem alpha-sialon). Samples made from the Chem alpha-sialon powder were hot-pressed under the same conditions for a comparison. Similar phase assemblages were obtained for the samples starting from Chem alpha-sialon powders, except for even more amount of betasialon phase contained. Material with a single alpha-sialon phase could be got in both samples when 10 wt.% additional slag and CaCO3 were introduced into the Slag alpha-sialon and Chem alpha-sialon starting powders respectively. (C) 2003 Elsevier Ltd. All rights reserved.