Cyclic Oxidation of 304L and 316L Stainless Steel Coated and Uncoated with Cr 3 C 2 –nicr at Elevated Temperatures

Failure of the boiler, gas turbine, incinerator, and other power-producing machines is mainly caused by the metals’ oxidation and alloys at high temperature service environment. It is a common practice to apply thermal barrier coating to increase the resistance to oxidation of metal alloys when subjected to high temperatures. In the current research, an effort has been made to apply a coating of Cr 3 C 2 –NiCr using the detonation gun (D-gun) technique on stainless steel (SS) 304L and SS 316L. The characteristics of coatings have been studied at 750 and 850°C. A cyclic oxidation process was carried out in a muffle furnace for 50 cycles. For each cycle, 304L and 316L SS, both bare and coated, are heated for 1 h in a muffle furnace and cooled for 20 min in ambient air. Under the investigated conditions, the Cr 3 C 2 –NiCr coating sprayed with a D-gun exhibited outstanding adhesion to the substrate alloy. A weight change/area versus the number of cycles plot has been drawn to understand the kinetics of oxidation. SS 304L coating has shown approximately 26.54 and 21.93% improvement in oxidation resistance at 850 and 750°C, respectively. For SS, 316L coating has shown approximately 27.67 and 25.92% improvement in the oxidation resistance, respectively, at 850 and 750°C. The oxide-scale-generated Cr 2 O 3 phase demonstrated notable resistance to oxidation throughout the 50 cycles of cyclic oxidation at 750 and 850°C. The weight change/area shows that 316L has much better oxidation resistance than 304L at both temperatures of 750 and 850°C. The application of such coatings at high temperatures may reduce the formation of oxide scale which attacks and corrodes exhaust valves, turbocharger nozzles, and blade.