Comparative Evaluation of Hot Corrosion Resistance of 83WC–17CO and 86WC–10CO–4Cr Coatings on Some Boiler Steels in Actual Boiler in Thermal Power Plant

Abstract

This research work was focused on the performance of HVOF-sprayed 83WC–17CO and 86WC–10CO–4Cr coatings on boiler steel alloys ASME SA213 T22 and ASME SA213 T91 in a coal-fired boiler environment. Both coated and bare steel alloys were subjected to cyclic exposures, in the superheater zone of a coal-fired boiler for 10 cycles at 900 °C to compare the effect of the coatings in actual boiler environment. During the study, each cycle consisted of 100-h heating followed by 1-h cooling at ambient conditions and thereafter thermogravimetric method was used to establish the kinetics of corrosion. Corrosion products were examined by x-ray diffraction, scanning electron microscopy/energy-dispersive spectroscopy techniques. The hot corrosion resistance of both the coatings 83WC–17CO and 86WC–10CO–4Cr coating was found better on ASME SA213 T22, whereas 86WC–10CO–4Cr coating showed the higher corrosion resistance on ASME SA213 T22 as compared to 83WC–17CO coating.