The thermal shock resistance of zirconia with 15 mole ' % titanium prepared either by cold-pressing and vacuum-sintering or by vacuum hot-pressing was determined by radially quenching disks with thermally insulated faces under various conditions of heat transfer. The thermal shock resistance of calcia-stabilized zirconia disks was determined for comparison. For quenches from below the transformation temperature range of zirconia, the thermal shock resistance of zirconia with 15 mole yo titanium was much better than that of calcia-stabilized zirconia, but for quenches from above the transformation range it was slightly inferior. The thermal shock resistance of zirconia with 15 mole %titanium is fairly insensitive to the methods of manufacture used in this investigation. In an attempt to identify the physical properties responsible for the improved thermal shock resistance of zirconia with 15 mole yo titanium, the heat capacity, thermal expansion, modulus of rupture, modulus of elasticity, and thermal conductivity as functions of temperature were determined.

The relatively good thermal shock resistance of zirconia with 15 mole yo titanium for quenches from below the transformation temperature of zirconia is attributed to the metal in the grain boundaries. The discrepancy between calculated and experimental thermal shock resistance of the same compositions for quenches through the transformation range is traced to the plastic behavior of these materials through the transformation range. The same type of plasticity was observed through the transformation range of zirconia-zirconium compositions. Metals other than titanium also improved the thermal shock resistance of zirconia.

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