On the adhesion of nitride coatings of HSS substrates

The adhesion of reactively rf magnetron-sputtered nitride coatings (TiN, HfN, NbN) on HSS substrates was studied as a function of substrate temperature (775-300 K) and sputtering atmosphere (various total pressures and different N2/Ar ratios). The adhesion was tested by means of the scratch test and correlated to the film morphology. The critical load, as measured by the scratch test, is influenced by the properties of the substrate, the deposition conditions, the properties of the coating and the testing method. These dependencies are discussed in detail. (author)