Surface morphology studies and corrosion behaviour of plasma sprayed Cr3C2/8YSZ composite coating on SS316

Abstract

Abstract Austenitic Stainless Steel (SS316) is a commonly used material in marine and offshore locations. The components’ surface in such environments degrades due to chloride and moisture exposure. Hence, adding a ceramic coating to the surface enhances its functionality. In the present work, Cr3C2 and 8YSZ powders are mixed in an equal ratio to deposit unique composite coated layers on the SS316 substrate by plasma spray coating method. The performance of the composite coating is also compared to that of uncoated, Cr3C2-coated, and 8YSZ-coated substrates. The surface morphology and cross-sectional microstructures of the coated SS316 substrate are examined using scanning electron microscope (SEM) images, and The presence of chemical elements in the coatings is determined using Energy Dispersive x-ray Analysis (EDAX) with elemental mapping. Further, the corrosion resistance of the substrate is evaluated using potentiodynamic polarisation and Electrochemical Impedance Spectroscopy (EIS) methods. The results show that the composite coating has a decreased porosity of 1.33% area and a higher microhardness of 880.02HV compared to bare and other coated surfaces. The corrosion analysis reveals that the composite coating has a decreased corrosion current density (Icorr) of 3.233 × 10–6 mA cm−2 and an enhanced charge transfer resistance of 2396.23 ohms.cm2 due to strong passivation and restricted electrolyte penetration into the coating. Further, the electrochemical corrosion study reveals that the composite coating exhibits the lowest corrosion rate of 0.00004306 mm / year.