Comparative investigation of surface modification and corrosion behaviour on SS304 and SS316 Coated with Inconel 625 in Air and Molten Salt Environment

Abstract

The high operating temperature-based industry extensively requires coating of material surfaces that are subjected to a high-temperature environment to improve their surface and resistance to corrosion. The current study investigated the surface modification and corrosion behaviour of Inconel 625-coated SS304 and SS316 materials in an air and molten salt environment at 800 °C. The plasma spray method was used to coat the Inconel 625 powder over the substrates. Techniques like quantitative weight gain/loss method, surface roughness, hardness measurement, and characterization through microstructure analysis were used to characterize and analyze the corrosion behaviour and microstructure of Inconel coated SS. It was observed that the coat had a noticeably layered structure with layers parallel to the surface of the substrate. The experimental results revealed that the uncoated SS suffered corrosion in the form of residue and peeling up of its oxide scale. Whereas the surface of the IN625-coated SS showed excellent resistance to corrosion formation. It was found that the coating lowered the mass gain of the SS316 by 65% when compared to uncoated SS.

High temperature corrosion performance of Inconel 625 hard overlays deposited on stainless steel substrate

“…The appearance of the iron oxides is because of the interaction between the molten salt and the alloy material due to the melting of the substrate at elevated conditions. [ 2 ]…”

“…Even though these materials have excellent properties, deterioration is common when exposed to harsh environments. [ 2 ] In the service life at high‐temperature conditions, the component is subjected to oxidation and reduction reactions, leading to the degradation of the equipment. [ 3 ] The corrosion effect on the boiler piping system is because of the entrapped deposits on their surface, mostly with molten salts like Na, S, K, and Cl, which are highly corrosive.…”