Specific Energy of Elastoplastic Deformation Required for Crack Formation at Indentation of Hardening Coatings

Abstract

Known methods for assessing the crack resistance of very hard or strengthened surface layers of materials by using a pyramid indenter are intended for the cases of the formation of radial cracks around the indent. However, at indentation of a pyramid into some types of hardening coatings, for example, made of titanium nitride, annular rather than radial cracks are formed around the indent. For this case of crack formation, we proposed to use the kinetic diagram of indentation for determination of the specific energy of elastoplastic deformation that is needed for the formation of the first visible crack. This energy can be used to compare the ability of the coating to resist crack formation of any kind.