Comparative hot corrosion performance of APS and Detonation sprayed CoCrAlY,NiCoCrAlY and NiCr coatings on T91 boiler steel

摘要

Hot corrosion performance of Atmospheric Plasma Spray (APS) and Detonation spray (DSC) CoCrAlY, NiCoCrAlY, and NiCr coatings on T91 steel were investigated at 650 degrees C for 100 cycles under Na2SO4-K2SO4-Fe2O3 mixed salt deposit in ambient air. The hot corrosion resistance of DSC coatings was found to be superior to their APS counterparts. Chromia and spinel oxides provided excellent corrosion resistance while no alpha-Al2O3 was observed. DSC NiCr and APS NiCoCrAlY offered the most and the least corrosion resistance, respectively. DFT calculation was performed to validate the thermodynamic stability of each oxide and identify the precise oxide formation.