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.