Abstract:

The longitudinal wave velocity and attenuation and shear wave velocity for machinable aluminosilicate glass-ceramic (MACOR) samples were measured as functions of frequency and temperature with the pulse-echo method. Frequencies of 5--30 MHz were used in the temperature range of 100--300 K. The velocity differences between 100 and 300 K were about 1% for longitudinal waves and 3% for shear waves. The monotonic decrease in the longitudinal attenuation coefficient between 100 and 300 K was approximately 50%. The longitudinal wave attenuation coefficient increases linearly with frequency and nonlinearly with decreasing temperature. This contrasts with the longitudinal and shear wave velocities, both of which decrease with increasing temperature. These data were used to calculate the elastic moduli, Poisson's ratio, and Lame parameters for the material. These results are interpreted in terms of thermal stress cracking and microstructure-related absorption.