ABSOLUTE HARDNESS OF FILMS AND COATINGS

Previously published hardness models are discussed and a new model is presented to obtain the absolute hardness of thin films or coatings. On the basis of the relative plastic deformation Of the coating and the substrate this approach takes into account the role of the interface by the introduction of a function related to the substrate and to the film hardness coefficient. The model is verified for titanium nitride films on different substrate materials. For thick coatings (i.e. > 50 mu m, depending on the film hardness) several models are used and compared. Finally, to. apply Jonsson's model for thick coatings a modification is proposed. The interest of such a modification is validated by experimental results obtained for thick chromium carbide coatings.