Cavitation-corrosion analysis of HVOF-sprayed WC-Co-Cr-graphene nanoplatelets coatings with LST pre-treatment

The maritime sector, vital for global economic growth, encounters challenges due to the corrosive aquatic environment, particularly concerning cavitation erosion (CE). CE is a leading cause of turbo-machinery failure, causing critical damage to essential components like propellers and naval hulls. Recent research focuses on materials with improved CE resistance, emphasizing advanced coatings. Tungsten carbide (WC) cermet coatings, often containing cobalt (Co) and chromium (Cr), show promise in enhancing wear resistance and reducing cavitation erosion. With an aim to increase CE resistance, this paper investigates the application of a WC-10Co-4Cr + graphene nanoplatelet (GNPs) coating on an IS-2062 steel substrate using the High-Velocity Oxygen Fuel (HVOF) technique in conjunction with laser surface texturing as a pre-coating preparation technique. Also, Response Surface Methodology (RSM) is utilized to study and optimize the coating's erosion behaviour, offering valuable insights for practical applications in challenging maritime environments. The analysis revealed that WC-10Co-4Cr + 2% GNPs has the highest cavitation resistance, when compared to other coating configurations. Further, the HVOF-coated specimens exhibited significantly improved corrosion resistance, as evident from lower corrosion current densities (I_Corr) ranging from 9.36 × 10⁻⁶ to 19.31 × 10⁻⁶ A/cm² compared to the pristine substrate (I_Corr = 66.32 × 10⁻⁶ A/cm²). Effect of GNPs was envisioned to be investigated, and the results reveled that the WC-10Co-4Cr + 2% GNPs coated surface demonstrated the most notable reduction in corrosion rate (9.36 mm/y), highlighting its superior performance, attributed to GNPs reinforcement and a Cr binder that minimized porosity and mitigated micro-cavities and pitting corrosion.