Influence of indentation depth and film thickness on composite hardness and modulus of coating-substrate systems

A method using one load-displacement curve to calculate composite hardness distribution of coating-substrate system was proposed and varified on Nano-II indenter. To take into account the variation of composite elastic modulus through the indentation depth and its effect on hardness measurement, the Gao's model was introduced in the present method. The results of electroless Ni-P coatings with different thicknesses indicated that the composite hardness calculated by the proposed method agrees basically with experimental data. It appeared to be most important that the true hardness of coatings can be predicted provided that several composite hardnesses have been obtained experimentally.