Comparative Assessment on the Behavior of HVOF Sprayed Ni-Based Alloy Coatings on SA213-T22 Boiler Tube Steel in Actual Biomass Fired Boiler Environment

Corrosion occurrence issue at high temperature has often come across in biomass boilers for the reason that burnt fuels mainly comprise of alkali, chlorine and other molten salts. Due to this, material depletion, leakages and unexpected shutdown of plants have been reported. Utilizing thermal spray for protective coatings is one of the striking solutions for obviating this issue. Commercial Inconel 625 and Inconel 718 powders were deposited on SA213-T22 boiler steel by means of a high velocity oxy-fuel (HVOF) spraying technique in the present investigation. In order to assess the performance of coating in actual environment, bare and coated samples were subjected to biomass-fired boiler for 15 cycles. The erosion-corrosion kinetics was determined using thickness loss data. The as-sprayed and eroded-corroded specimens were examined using different characterization techniques. XRD and SEM/EDS were utilized for examining the phases and surface morphologies of powder, coating and eroded-corroded samples. The HVOF sprayed coated steel outperformed than the bare steel in actual boiler environment.