Contact-Damage Behavior of Textured and Random Alumina Ceramics under Hertzian Indentation

Two alumina ceramics with different microstructures were prepared by tailoring the processing conditions. In one of them, elongated alumina grains were aligned parallel to each other ("textured" material), whereas in the other, the elongated grains were uniformly distributed ("random" material). Hertzian indentation was performed on these two materials. The results showed that, although both materials exhibited a diffuse damage zone rather than typical cone cracks, the extent of damage in the textured material is significantly less than that in the random material. The difference in damage behavior between these two materials was interpreted with the aid of the contact-stress field. A new microstructural design method for improving contact-damage resistance is suggested, based on the present results.