THE EFFECT OF Cr INTERLAYER ON THE CRYSTAL STRUCTURE AND CORROSION RESISTANCE OF CrN COATING ON STEEL

In this study, chromium nitride (CrN) hard coatings on stainless steel substrates with chromium (Cr) interlayers incorporated between the coatings and the steel substrates in order to improve adhesion of the coatings are investigated. Cr layers are prepared using d.c magnetron sputtering, and then CrN coatings are prepared using reactive d.c magnetron sputtering on these Cr layers. The effect of the Cr layer on the crystal structure and corrosion resistance of the CrN coating through surface modification is determined. The results show that regardless of whether the coatings include the Cr layers, face centered cubic structure of CrN phase with the preferred orientation on (111) planes parallel to coating surface remains and grain size of the CrN does not change. Nevertheless, the Cr layer induces stronger the (111) peak, reduces the residual stress and increases corrosion resistance of the CrN coatings. In addition, corrosion resistance of CrN coatings with the Cr layers deposited at different substrate bias and deposition time is similar although (111) peak intensity and residual stress of them change. The crystal structure and protection ability of the CrN/Cr coatings are optimum for Cr layers deposited with substrate bias of -60V and deposition time below 10min.