ESTIMATION OF THERMAL-SHOCK RESISTANCE OF AL2O3 CERAMICS BY LASER IRRADIATION

Various structural ceramics have been developed as heat-resistant mate rials. In some applications it is anticipated that they will be expose d to very-high-temperature environments of the order of thousands of d egrees. Moreover, these ceramics are subjected to thermal loadings whi ch change rapidly with time, Therefore, it is very important to invest igate their thermal shock characteristics. In this report, the distrib utions of temperatures and thermal stresses of cylindrical-shaped Al2O 3 ceramics under irradiation by laser beams are analyzed using the fin ite element method, Critical fracture curves are obtained from the rel ationships between spot diameters of laser beams and maximum values of thermal stresses for various power densities of laser beams. The irra diation experiments yield these critical fracture curves, and theoreti cal and experimental curves are in good agreement.