Study on Microstructure and Cyclic Oxidation Behaviour of WC-CoCr Cermet-Based Plasma-Sprayed Coatings Developed on the Austenite Steel

The cyclic oxidation behaviour of WC-10Co-4Cr powder coatings made by plasma spraying on austenitic AISI 316L stainless steel at 850 degrees C for 50 cycles was investigated. The rate of oxidation was compared in terms of measurements of the weight changes of coated and uncoated samples. Using scanning electron microscopy (SEM), the microstructure of the coating was observed both before and after cyclic oxidation. X-ray diffraction (XRD) was used to determine the presence of formed phases. The oxide scales formed on the coated austenite steel samples after oxidation in air were studied using XRD, SEM, and energy-dispersive spectroscopy (EDS). The uncoated AISI 316L steel had severe spalling, peeling off, and sputtering from its oxide scale. Additionally, the scale was rich in Fe2O3, which contributed to the significant weight gain. The findings showed that coatings outperform uncoated materials in terms of oxidation resistance. The coating lowered the weight gain of austenite 316 steel by 84.34%. It was also discovered that the protective WO3 and Cr2O3 phases generated on the oxide scale provided significant oxidation resistance.