CHARACTERISTICS OF RAPIDLY SOLIDIFIED MULLITE CERAMIC POWDER PARTICLES CONTAINING ZIRCONIA

Mullite ceramics containing zirconia were rapidly solidified (RS) to o btain amorphous powder using Plasma Centrifugal Atomization. The morph ology, thermal properties and mechanical properties of individual RS a morphous (RSA) powder particles were investigated. The mechanical and thermal properties of RS crystallized (RSC) powder particles were stud ied for comparison. The hardness of RSC powder appeared to be independ ent of zirconia content, unlike the fracture toughness, which increase d with zirconia content. The fracture toughness of RSA powder was high er than that of RSC powder. The RSA powder exhibited a strong exotherm ic peak in DTA and a high degree of shrinkage in a dilatometric examin ation. The results obtained in this investigation are discussed in ter ms of the ultrafine microstructure exhibited by the RSA powder. (C) 19 98 Acta Metallurgica Inc.