A model for hardness determination of thin coatings from standard micro-indentation tests

Determination of surface hardness of thin films using standard micro-indentation testers has to address the problem of the range of indentation loads available with these testers. In fact, they are often too high to allow the direct determination of the film hardness without involving a contribution of the substrate. As a consequence, the calculated hardness value is not the hardness of the film but an apparent surface hardness. Since this “composite” hardness is the result of two contributions, models are necessary to separate them in order to determine the true film hardness. The application of such models may however require the introduction of coefficients or data or involve some other adjustment method. In order to avoid the need for such other data parameter, we propose a new model, which gives predictions in good accordance with the average ones of the other models.