Erosion–corrosion behaviour of HVOF coated WC-10Ni-5Cr coatings on 35 CrMo steel

The degradation of engineering materials owing to erosion–corrosion remains a critical challenge in industries such as marine, oil and gas, mining, and slurry transportation, where components are exposed to aggressive environments. This study investigates the effectiveness of High-Velocity Oxyfuel (HVOF)-sprayed WC-10Ni-5Cr coatings in enhancing the erosion–corrosion resistance of 35CrMo steel, a widely used structural material in such demanding applications. The erosion–corrosion behaviour of WC-10Ni-5Cr coatings was systematically analysed in a 3.5 wt-% NaCl solution containing silica sand as the erodent under varying operational parameters, including sand concentration, rotational speed, and exposure time. Microstructural characterisation, volume loss measurements, and surface morphology analyses were conducted to elucidate degradation mechanisms. Results reveal that uncoated 35CrMo steel exhibits a severe volume loss of 3.21 mm³, whereas the coated counterpart demonstrates a significantly lower volume loss of 0.056 mm³, corresponding to a 76% reduction in material loss. Also, corrosion rate analysis indicates that the uncoated steel corrodes at 0.417 mils per year (mpy), whereas the WC-10Ni-5Cr coating reduces the corrosion rate to 0.108 mpy, representing a 74.1% improvement in corrosion resistance. This study conclusively establishes that HVOF-sprayed WC-10Ni-5Cr coatings offer exceptional protection against erosion–corrosion, significantly extending the service life of 35CrMo steel in aggressive environments.