Cavitation erosion resistance of Ti/TiN multilayer coatings

The results of cavitation erosion tests of the Ti/TiN multilayer coatings protecting the X6CrNiTi18-10 steel are presented in this paper. The Ti/TiN multilayer coatings were deposited on the X6CrNiTi18-10 steel surface by means of the cathodic arc evaporation PVD method. The multilayer coatings were deposited as 4, 12 and 40-layer structures with the Ti layer at the bottom and the TiN layer on the top. All layers showed similar thickness; the total thickness of the Ti/TiN multilayer coatings was approximately 4 μm. ated specimens showed better cavitation erosion resistance than the uncoated stainless steel. With an increase of the number of coating layers the cavitation erosion resistance of the Ti/TiN multilayer coating was lower. It was shown experimentally that the Ti/TiN-4 coating provided the best protection against cavitation erosion. gree of cavitation erosion was estimated by mass measurements and surface roughness measurement tests. The value of surface roughness of the Ti/TiN-4 coating was closest to that of the uncoated steel. The surface profiles of the Ti/TiN-12 and Ti/TiN-40 coatings showed little undulation, not visible in the profiles of the Ti/TiN-4 coating and the uncoated X6CrNiTi18-10 steel. The microscopic observation showed that deformation of the multilayer coatings developed via cracking, which further propagated by simultaneous fracture of numerous coating layers.