Higher operating temperatures coupled with biomass-derived fuels can lead to aggressive corrosion damage to the superheater/reheater tubes in power plants. In this study, a HVOF sprayed NiCr coating was deposited onto a 9 % Cr substrate, which were exposed in simulated coal-biomass combustion gases with a screening deposit containing Na2SO4, K2SO4 and Fe2O3 at 700-750°C for 1000 h. The tests were carried out using the “deposit-recoat” test method and pre and post-exposure dimensional metrology was used to quantify the coating damage in terms of metal loss distributions. The exposed samples were also examined in a SEM/ EDX. The coatings developed a protective Cr2O3 layer at the coatings/ deposit interface and a Cr depleted zone was observed underneath the oxide layer. NiCr coating provided suitable corrosion protection with a median metal loss of ~35μm in 1000h.

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