Using The Ultrasonic Waves For Studying Thermal And Elastic Properties as a Function of Porosity in Sintered ceramic

Ultrasonic pulse echo measurements on porous alumina as ceramic material with porosities ranging from (20-40)% showed effect of volume fraction of porosity on both thermal and elastic properties. A quadratic relationships, by using a least squares method, is deduced for the dependence of the shear velocity, longitudinal velocity, shear modulus, Young s modulus, bulk modulus, Poisson s ratio, Debye temperature, specific heat, and thermal conductivity on the total porosity. By these relationships, the thermal and clastic properties results of pore-free alumina were calculated. The elastic properties results of ceramic decrease substantially with increasing porosity, except Poisson s ratio which is the constant. Debye temperature and thermal conductivity decrease too substantially with increase of porosity, while specific heat increases.