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. O n 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 comp ared. Finally, to. apply Jonsson's model for thick coatings a modifica tion is proposed. The interest of such a modification is validated by experimental results obtained for thick chromium carbide coatings.