NONDESTRUCTIVE CHARACTERIZATION OF ZIRCONIA-TOUGHENED ALUMINA CERAMICS USING ULTRASONICS

Ultrasonics has been used for the characterization of sintered zirconi a-toughened alumina (ZTA) ceramics. The variation of ultrasonic veloci ty with volume fraction of zirconia in an alumina matrix was studied. Variation of ultrasonic velocity with volume fraction of ZrO2 content was analysed in terms of a second-degree polynomial in the volume frac tion of ZrO2. The elastic moduli and Poisson's ratio evaluated from th e longitudinal and shear velocities have also been described in terms of a similar equation. The observed variation in velocity and moduli w ith porosity has been compared with the predicted values based on elas ticity theory.