The hardness of thin film coating is one of the analysis indicators of its quality. There are many hardness testing methods. Yang Guang and Ge Zhihong systematically introduced two methods of film hardness testing in their paper "Comparison of Several Hardness Testing Methods of Thin Film Coatings" : Direct test method, indirect test method, direct test method is to use microHardness Tester and nano indenter to test, and indirect test method is to use Jonsson-Hogmark (JH) formula to calculate the coating film hardness and extrapolation method to calculate layer film hardness. Finally, the advantages and disadvantages of several methods are analyzed and compared.
The conclusion is that indirect method measurement is more troublesome than direct method measurement. If the intrinsic hardness of the coating is not required, but only to compare the hardness value of the film, the composite hardness comparison of equal load or equal film thickness can be used, and it is not necessary to separate the hardness value of the film. For specific information, please read the original text of "Comparison of Several Hardness Test Methods for Thin Film Coatings".
