ABSTRACT
This chapter discusses some of the materials in the second row of the matrix of zirconia-toughened ceramics as classified by Nils Claussen. The development of toughened alumina-zirconia composite systems occurred almost simultaneously with the conceptual breakthrough in partially stabilized zirconias systems. The successful development of zirconia-dispersed nonoxide materials has been much slower than for oxide materials. The actual particle sizes of the zirconia in the fabricated bodies are somewhat larger than the admixed size. At low volume fractions, zirconia acts as a dispersed, inert phase in terms of sodium ion conduction and, thus, will tend to block ionic conductivity. Increasing the mechanical properties, particularly the toughness, has been demonstrated to greatly improve the toughness and thermal-shock resistance of zirconia-containing materials. The toughness, as measured by the indentation technique, was found to depend upon volume fraction of zirconia, particle size, and porosity.
