Enhancing the high-temperature corrosion resistance of HVOF-sprayed NiCoCrAlY coating in marine environment by Pt modification and pre-oxidation

Abstract

To prolong the service lifetime of hot-section components used in marine environment at elevated temperatures, it is crucial to explore and develop high-temperature corrosion-resistant coatings. High-velocity oxygen fuel (HVOF) sprayed NiCoCrAlY, Pt-modified NiCoCrAlY and pre-oxidized Pt-modified NiCoCrAlY coatings were prepared and investigated. This study is concerned with the performance of three coatings in a simulated marine environment based on the phase composition of corrosion products and microstructure evolution of coating samples combined with first-principles density functional theory. The results show that the NiCoCrAlY coating was subject to accelerated corrosion and extensive aluminum depletion, leading to premature coating failure. The high-temperature corrosion resistance of Pt-modified NiCoCrAlY coating was found to be better than that of NiCoCrAlY coating. In contrast, the pre-oxidized Pt-modified NiCoCrAlY coating offered long-lasting protection and exhibited the best corrosion resistance, which is attributed to the positive synergistic effect between Pt modification and pre-oxidation.