Characterization of alumina ceramics by ultrasonic testing

Some material characteristics of alumina ceramics, e.g., porosity, Youngʹs modulus and Poissonʹs ratio, have been evaluated using ultrasonic sound. Experimental results showed that the velocity of an ultrasonic sound wave in alumina ceramics decreased proportionally with increasing porosity. Youngʹs modulus and Poissonʹs ratio calculated from the longitudinal and transverse ultrasonic velocities were found to be dependent on porosity. The results from the present program have been compared with data from the literature, and similarities and differences discussed. The deviation of these data from a theoretical prediction may be due to the texture of the porosity introduced by different alumina-forming processes.