Hot Corrosion Evaluation of Cr3C2/8YSZ-Based Plasma-Sprayed Coatings on SS316 in Na2SO4–V2O5 Molten Salt Environment at 700 °C

Austenitic stainless steel used in power plants and chemical industries is susceptible to corrosion in high-temperature environments. The corrosion is accelerated in high-temperature applications due to chemical substances like sodium, sulfur, and vanadium. The current investigation involves the assessment of the hot corrosion performance of two distinct coatings, namely 8 wt.% yttria-stabilized zirconia (8YSZ) and chromium carbide (Cr3C2), which have been applied using air plasma spraying onto SS316. Coatings were analysed after being heated in the furnace for 50 h at 700 °C at 5 h/cycle with a salt mixture of Na2SO4− 60 wt.% of V2O5 (30 mg/cm2). Elemental analysis of the hot corroded specimen was performed using scanning electron microscopy (SEM), x-ray diffraction analysis (XRD), and energy-dispersive spectroscopy (EDS). The findings indicate that the 8YSZ coating exhibited enhanced adherence to the substrate for the entire duration of the hot corrosion test. In contrast, it was observed that the Cr3C2 coating underwent total delamination subsequent to the fifth cycle of the hot corrosion test. Bare material shows a substantial degradation surface that peels off without substantial formation of strong surface adherence corrosion products.