The analysis of different fracture toughness models for PVD coatings

The materials' resistance to brittle fracture is a very important parameter for the characterization of PVD coatings.The fracture toughness of solid materials is determined by the critical value of the stress concentration coefficient KIc [1,2].There are different models for determining the KIc coefficient of thin coatings.The most often used is the method proposed by Niihara [3] and Laugier [4].In this work, the authors present the possibility of characterization of the fracture toughness in mode I (KIc) for selected PVD coatings.The Young's modulus, hardness and fracture toughness of these coatings are extracted from nanoindentation experiments.The fracture toughness was evaluated using the calculation of crack length measurement, which was generated by the Vickers and Berkovich indenter.An important observation is that it is possible to use the micro indentation and nanoindentation methods for the mechanical characterization of micro-volume systems.