THE HOT HARDNESS TESTING FOR SUPERPLASTICITY IN NANOCRYSTALLINE YTTRIA-STABILIZED TETRAGONAL ZIRCONIA

Yttria Stabilized Tetragonal Zirconia (YSTZ) (3 mol% Yttria) was synthesized by a sol-gel chloride route. YSTZ sintered to > 99% theoretical density at temperatures above 1225 °C. This was used as starting material to perform hot hardness measurements. The hot indentation technique was used as a quick and convenient method to obtain preliminary information on the high temperature deformation characteristics of zirconia. Vickers micro-hardness measurements were carried out in the temperature range from room temperature to 1250 °C. Indentation size was in the range 25 to 250 μm. The temperature for the onset of superplasticity was determined to be about 1100 °C from a plot of hardness against temperature. The activation energy for superplastic deformation was determined to be approximately 550 kJ mol. © 1995.