In-situ observation of Hertzian cracks in indentation damage of brittle materials

In-situ observation of Hertian crack growth of brittle materials in indentation tests were carried out using soda lime glass bars as the model materail. Silicon nitride, alumina and hardened steel spheres were used for the indenter. The cracking behavior was observed continuously during loading by a CCD camera with lens assembly installed behind the glass bar. The cracking behavior was also monitored by acoustic emission (AE). The stress filed at the interface in sliding contact was estimated using the determined indentation strength, then the effect of cracking behavior on the wear of the glass bar was examined. As results, the interaction of the crack growth in sliding contact forms larger wear debris and shows greater wear loss.