Effect of Indenter Materials on Hertzian Crack Growth of Alumina Ceramics

摘要

Our study describes the effect of indenter materials on Hertzian cracking behavior of alumina ceramics in sphere indentation. Numerical analysis (finite element modeling, FEM) was applied to investigate the influence of the coefficient of friction at the interface on the stress distribution near the contact area. Cemented carbide (WC-Co), silicon nitride, alumina, and hardened steel spheres used for the indenter were penetrated into the alumina disc with an electromechanical testing apparatus at a constant crosshead speed in air. The indentation fracture was monitored with acoustic emission. FEM shows that the stress distribution is different depending on the elastic modulus of the indenter when the deformation at the interface is restrained by frictional resistance. The experimental data reveals that the ring crack radius and the indentation strength also depend on the elastic modulus. From the results of numerical analysis and experimental data, we found that the minimum value of the ring crack radius corresponds to the position of maximum tensile stress.