SINTERING AND CHARACTERIZATION OF POLYCRYSTALLINE MONOCLINIC, TETRAGONAL, AND CUBIC ZIRCONIA

Polycrystalline monoclinic (m), tetragonal (t), and cubic (C) ZrO2, sintered at 1500-degrees-C, were annealed in the cubic stability field and rapidly cooled to permit the displacive c --> t' transformation to occur in compositions containing 0-6 mol% Y2O3. The bulk fracture toughness of coarse-grained (>25-mu-m) m, t', and c zirconias were compared with conventionally sintered, fine-grained (typically less than 1-mu-m) materials. The ferroelastic monoclinic and tetragonal zirconias were more than twice as tough as paraelastic cubic zirconia.