Study on Absolute Hardness of Thin Films by Monolayer Model Application

Abstract

In order to determine the absolute hardness of film or coating, it is necessary to separate the contribution of substrate. It is known that the film thickness and on the applied load are generally the principal two parameters that can determine in this case the absolute hardness of film.  The apparent hardness values obtained from indentation measurements are the result of the contributions of the substrate and the film. In order to determine the true hardness of the film, these two contributions must be separated. Several authors have worked on this topic over the years, and there are a large number of models written under an additive linear function that are available in the literature. The purpose of this research is to determine the absolute hardness of nitride thin layers produced by two activation rates of plasma of 50% and 65%. At the surface of the specimens, a series of classical Vickers indentation at various loads was applied. The separation of substrate contribution of the  on the measurement hardness of the film reported in the literature is very complicated due to several parameters that they intervene, and for this reason, we used in this study Jonsson- Hogmark model (J-H) which is simple and  gives according to the several previous studies the best results.