Indenter wear study and proposal of a simple method for evaluation of indenter blunting

Knowledge of indenter shape and its blunting is crucial for exact evaluation of the indentation data and mechanical properties derived from them. In this study, the evolution of the Berkovich indenter tip with increasing number of indentations into fused silica and sapphire was described using a spheroconical model. It was found that the indenter tip radius increases by ~ 7% after several thousands of indentations into sapphire. In the second part of the paper, the shape of a large number of indenters in various states of use was evaluated using the same spheroconical model. The relation between the indenter tip radius, maximum indentation depth and elastic to total work of indentation ratio at 1 mN on fused silica was investigated. The correlation of indenter radius and maximum indentation depth at 1 mN is very convincing and it can be used as a fast and simple estimation of the indenter bluntness. Graphic abstract