Correlation Between Mechanical Properties and Cavitation Erosion Damage of Carbide and Nitride Thick Coatings for Turbomachinery Applications

Abstract

The cavitation erosion resistance of carbide and nitride thick (up to 20 μm) coatings by means of the rotating disk testing method was analysed in the present study. The effect of the coatings composition and mechanical properties on the damage mechanism and material weight loss has been confirmed. Results show that all coated samples under investigation are characterised by lower cavitation wear than that of the uncoated ones. Both nitride TiN, CrN, and carbide CrC coatings significantly improve erosion resistance of the stainless steel samples. The correlation between the evolution of mechanical properties of both nitride and carbide coatings and weight losses has been investigated. The differences in the composition affect the mechanical properties of coatings and, finally, cavitation erosion resistance of tested materials. Furthermore, the CrC coated samples have shown improved elastic behaviour and high resistance to plastic deformation as compared to the CrN and TiN coated ones. Young modulus E and hardness H parameters of coatings exceed those estimated for the reference samples. The higher H/E and H3/E2 coefficients in the case of carbide coatings in comparison with nitride ones and reference samples have been established. CrC thick coatings with the ability to form nanocrystalline structure and higher mechanical parameters demonstrate the best protective efficacy for various anti-erosion applications.