Tribo-corrosion, mechanical and morphological performance of multilayer ceramic deposited on cast iron via HVOF thermal spray

This study investigated the mechanical, morphological, tribological and electrochemical performance of a multilayer deposited coating of Al₂O₃ and TiO₂ over the cast iron substrate using the HVOF thermal spray coating method. The morphological study revealed the deposition mechanism and confirmed that the coating materials achieved the desired thickness on the surface. The microhardness of the coated sample and the substrate material was measured. The residual stresses induced in the material were investigated by X-ray residual stress analyzer. The coated specimen was investigated on the high-temperature rotary tribometer at constant load of 20 N, the sliding speed and temperature were kept variable i.e 0.75 m/s, 1.25 m/s, 1.75 m/s and ambient 150°C and 300°C respectively. The tribological behaviour was compared with the substrate material. The results showed a decrease in the specific wear rate by ∼57 % as compared to pure cast iron. The SEM investigations reveal that the predominant wear mechanisms observed were smearing shown by the plactice deformation zone and abrasion shown by scratches and wear debris over the surface. The breakdown voltage for substrate and coating was −0.46 V and −0.38 V, showing the more corrosion resistance of the coated samples.