Corrosion and Cavitation Performance of Flame-Sprayed NiCrBSi Composite Coatings Reinforced with Hard Particles

To enhance the operational life of hydraulic machinery, protective coatings against wear, particularly cavitation erosion, and corrosion might be applied on the surfaces of components. The experiments conducted in this study aimed to assess the suitability of 80/20 NiCrBSi/WC-Co composite coatings for this purpose. A coating of NiCrBSi self-fluxing alloy, which served as the reference material, was deposited alongside a NiCrBSi coating reinforced with 20% WC-Co, both applied by flame spraying onto X3CrNiMo13-4 substrates, the martensitic stainless steel type frequently utilized in turbine blade manufacturing. The improved density of the coatings and adhesion to the substrate was achieved by remelting with an oxyacetylene flame. The cavitation and corrosion performance of both the reference and composite coating were evaluated through cavitation tests and electrochemical measurements conducted in the laboratory. The results demonstrate that the addition of 20% WC-Co significantly enhances the cavitation resistance of the composite material, as evidenced by the reduction to 3.76 times of the cumulative erosion (CE), while the stabilization rate remained at half the value observed for the reference self-fluxing alloy coating. Conversely, the addition of WC-Co into the NiCrBSi coating resulted in a slight decrease in the corrosion resistance of the self-fluxing alloy. Nevertheless, the corrosion rate of the composite coating (124.80 µm/year) did not significantly exceed the upper limit for excellent corrosion resistance (100 µm/year).