Abstract
In this study, HVOF thermal spray technique was used to deposit Ni-20Cr coating on a commonly used boiler steel ASTM-SA213-T22.The specimens with and without coating were subjected to cyclic oxidation testing at an elevated temperature of 900°C to ascertain usefulness of the coating for 50 cycles. Each cycle consisted of 1 hour heating in a silicon carbide tube furnace followed by 20 min cooling in air. Mass change technique was used to approximate the kinetics of oxidation. The uncoated sample suffered intensive spallation along with a significant overall mass gain. The oxidation rate was found to reduce appreciably after the deposition of the coating by 91%. The exposed specimens were characterized by X-ray diffraction [XRD] and scanning electron microscopy/energy dispersive spectroscopy [SEM/EDS]. It was observed that HVOF-sprayed Ni-20Cr coating was suitable to provide oxidation resistance to the given steel in the air environment.
