Lead-bismuth corrosion resistance of Ni-Al intermetallic compound layer prepared on 316L surface

A layer coating of Ni60 alloy powder was deposited on the surface of 316L stainless steel by laser cladding technology, and pure Al coating was prepared on the surface of Ni60 alloy coating by thermal spraying technology. Then, Ni-Al intermetallic compound was generated between Ni60 alloy coating and pure Al coating by 620 ℃×5 h high temperature diffusion test. Finally, the specimens prepared with Ni60 alloy and Ni-Al intermetallic compound coating were placed in liquid lead-bismuth alloy for 400 ℃×500 h to conduct corrosion test. SEM and XRD were used to test morphology, phase composition and element distribution of surface and section of intermetallic compound coating before and after corrosion, and corrosion resistance of Ni60 alloy coating and intermetallic compound coating in liquid lead-bismuth at 400 ℃ was analyzed. The test results showed that after high temperature diffusion test, a layer of Ni-Al intermetallic compound composed of Ni3Al and NiAl was generated on the surface of specimens. After 400 ℃ liquid lead-bismuth alloy corrosion test, surface corrosion of Ni60 alloy coating was more serious, a large number of metal elements on the surface were oxidized and dissolved, and discontinuous metal oxides and corrosion pits were formed on the surface of specimens. Ni-Al intermetallic compound coating was oxidized and became a stable metal oxide coating, which could effectively prevent Pb, Bi, O and other elements from penetrating into substrate and improve corrosion resistance of 316L to liquid lead-bismuth.Highlights: Intermetallic compounds were prepared by laser cladding, thermal spraying and high temperature diffusion, and corrosion situation of intermetallic compound layer in liquid lead-bismuth alloy was studied.