Effect of burnishing on HVOF coated boiler steel against hot corrosion in actual boiler environment

Hot corrosion of boiler tubes used in steam-generating systems has been recognized as a severe problem, resulting in tube wall thinning and premature failure. In this study, the effect of burnishing the thermal sprayed coatings against high-temperature corrosion of SA213-T22 boiler steel in actual environmental conditions of coal-fired boiler has been investigated. An experimental study was carried out for ten cycles, where the individual cycle consists of one-hundred hours of exposure trailed by one hour of ambient cooling. The hot corroded specimens are visually inspected at the end of each cycle to check for any variation in colour, luster, spalling tendency, and other physical changes in scale. The tested specimens were characterized through Thermogravimetric Technique, Microhardness Tester, Optical Microscope, Scanning Electron Microscope, and X-Ray Diffractometer to study their hot corrosion performance. The findings of this work suggest that burnishing can be potentially used for providing superior hot corrosion protection to any of the thermal sprayed coated specimens.