Cavitation erosion of TiN and CrN coatings deposited on different substrates

TiN and CrN coatings with various thicknesses deposited on X6CrNiTi18-10 and X39Cr13 steel by means of the cathodic arc evaporation method were tested in a cavitation tunnel with a slot cavitator and tap water as the medium. Steels were subjected to thermal treatment in order to obtain substrates of different properties. Present investigation shows that the properties of the substrate, especially the thermal properties, influence the properties of the TiN coatings. Deposition of hard TiN and CrN coatings on the steel substrates has caused the improvement of the cavitation erosion resistance. The increase of coating thickness decreases the positive effect of the TiN and CrN coatings deposition. The 8 and 12 μm thick TiN and CrN coatings undergo degradation mostly via spalling by removal of the thin flakes of the coating. The resistance parameter, image where k is thermal conductivity, α is the thermal expansion coefficient, H is the hardness in GPa, LC2 is the adhesion force in N obtained in the scratch tests, E is the Young’s modulus in GPa, pc is the number of phases in the coating phase composition, h is the coating thickness in μm, subscript c applies for coating, s is for the substrate, has been positively verified by present investigations. This indicates that not only the mechanical properties of the coating and of the substrate influence the cavitation erosion resistance of the PVD coating–steel substrate system, but also their thermal properties.