Investigation of High-Velocity Oxy-Fuel Thermal spray Coating over Mild Steel Surface as Replacement for Stainless Steel Material

The critical components in earlier were manufactured by mild steel but due to low corrosion resistance, stainless steel and aluminium alloy are being utilised. However a component of aluminium alloy has to be enriched by anodizing for long durability and better corrosion resistance. But peel off, pit formation, low adhesion and white rust formation are still the downfalls faced by the industries in the coated components over cyclic duration.

High-Velocity Oxy-Fuel (HVOF) thermal spraying is an adaptable method that can produce high-density coating with less than 1% porosity, high resistant to chemical environment providing better adhesion and increase the life of mating components. Though stainless steel and anodized aluminium alloy offers far superior life span and corrosion resistance but still more expensive than mild steel. This work evaluates the behaviour of HVOF thermal sprayed with tungsten, nickel and chromium containing WC-Cr₃C₂-Ni coating material over mild steel were found to have better corrosion behaviour, mechanical, tribological and thermal properties as stainless steel and anodised aluminium exposes. To examine the properties of coated mild steel, prepared specimens were taken for salt spray chamber test to evaluate corrosion resistance and tribological behaviour were studied under dry sliding condition at a applied load of 40N at sliding distance of 3000m in room temperature. In this process due to the high velocity of the stream particles of higher percentage reached the substrate surface in a partially melted. Also coated specimen surface were tested for hardness at both conditions of before and after tribo test. Improved surface properties such as high corrosion resistance and hardness might be due to presence of thermal sprayed tungsten nickel and chromium elements. Significant improvements in the wear resistance are due to the formation of lubricious WO₃. Therefore HVOF method coated mild steel with WC-Cr₃C₂-Ni might be an alternate to replace expensive stainless steel and anodized aluminium alloy components in the chemical environment.