Indentation of Coatings at micro/nano scale: Crack formation and deflection

Nanoindentation is an effective way of finding mechanical properties at nanoscale. They are especially useful for thin films where elimination of the substrate effect is required. The mechanism is based upon depth sensing indentation based on Oliver and Pharr modeling. Nanoindentation was used to evaluate the nanomechanical and fractographic properties of hard coatings deposited by magnetron sputtering. Radial and lateral cracks accompanied by delamination of the coatings were observed during the indentation tests. A novel phenomenon of stress induced crystallization was observed in case of the CNx films which resulted in crack deflection. Indentations at micro scale using Vickers Indenter were also done and the cracking phenomena were analyzed.