Cyclic oxidation behaviour of plasma sprayed metallic coatings

High temperature Co- and Ni-based metallic coatings of various compositions were applied on SS-310 samples using plasma spray technique. The coated samples were exposed to air under cyclic conditions at 900°Cfor upto 100 h.Adhesion of coatingswasmeasured using standard ASTM C 633-79 method. Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy was used to determine the surface morphology and microchemical constitution of coatings. X-ray diffraction was used to identify different phases formed during oxidation. Experimental results indicated that high temperature oxidation ofSS-310 alloywas greatly reduced by all coatings. The plasma sprayedmetallic coatings on SS-310 alloy performed better than that of bare SS-310 under the selected test conditions. Moreover, when compared among the selected metallic coatings used in the study, the Co-based coatings with higher Cr concentration exhibited superior performance compared to Ni-based coating with lower Cr concentration during the reported cyclic exposure.