Quantitative evaluation of adhesion of diamond coatings

Abstract

This paper presents a model to evaluate quantitatively the adhesion of diamond coating according to indentation tests. It is found that small indentation load causes round spallation of the coating, no matter what the shape of the indenter. An exponential sink-in deformation of the coating under the indentation is proposed [y = −a × exp(−bx)]. The deformation stress at the spallation edge is considered the coating adhesion. Using an experimentally observed relation of the indentation load versus the film spallation radius, we evaluate the adhesion of a diamond coating on copper to be about 1.921–1.956 GPa, which is in agreement with thermal quench results. The validity of this model is also verified by its self-consistence.