Achieving superior hot corrosion resistance by PVD/HVOF duplex design

In this study, an optimized duplex coating, consisting of a thick Cr3C2-NiCr interlayer and a top CrN film, were designed and deposited by HVOF and PVD. And then hot corrosion behaviors were systematically investigated, and corresponding corrosion mechanisms are discussed in detailed. Results showed that the thickness of the oxide scale of duplex coating is approximately one-tenth that of the Cr3C2-NiCr coating. Due to the formation of Cr2O3 oxide film, the CrN/Cr3C2-NiCr duplex coating exhibits superior hot corrosion resistance. However, chlorine-induced corrosion in uncovered holes is the main cause of local failure of duplex coating.