Environmentally Sustainable Optimization of Plasma Spray Technique for Chromium Oxide Coatings on SS306 Steel

This study investigates the plasma spray coating of chromium oxide nanoparticles (nCr2O3) on SS306 stainless steel substrates to enhance surface performance, addressing the growing demand for elevated-temperature, wear resilience coatings in engineering uses. Utilizing a Taguchi L9, the impact of key process parameters, viz., plasma arc current (PAC), plasma gas flow rate (PGFR), carrier gas flow rate (CGFR), and spray distance (SD), were optimized using desirability function. ANOVA test revealed SD as the most influential factor for micro-Vickers hardness (p = 0.0027) and % porosity (p = 0.0109). Optimal parameters (PAC = 500 A, PGFR = 40 L/min, CGFR = 2 L/min, SD = 100 mm) resulted in a maximum predicted hardness of 726.58 HV and minimum porosity of 3.24%. A confirmation trial showed a 1.27% increase in hardness and a 4.52% reduction in porosity over predicted values. Formation of a dense, homogenous coating with minimal surface defects was confirmed by SEM analysis. The integration of nCr2O3 with optimized process parameters significantly enhances coating quality through improved particle melting, splat formation, and grain boundary strengthening.