AN EXPERIMENTAL STUDY OF THE KINETICS OF THE TETRAGONAL TO MONOCLINIC PHASE TRANSFORMATION OCCURRING DURING THE LOW TEMPERATURE ENVIRONMENTAL DEGRADATION OF ZIRCONIA CERAMICS

摘要

The isothermal tetragonal to monoclinic phase transformation that occurs in zirconia ceramics during low temperature environmental degradation (LTED) at 80 to 160°C was examined using x-ray diffraction (XRD) and white light interferometry (WLI) techniques. Analysis of the data using the Johnson-Mehl-Avrami (JMA) equation indicates that growth is in three directions and that the nucleation rate is constant. The WLI data indicated that the growth rate is independent of hydrothermal aging time. Nucleation and growth data from WLI in conjunction with the Johnson-Mehl-Avrami equation predict monoclinic content vs. time data that are in good agreement with the XRD results.