Fe-based amorphous coating prepared using high-velocity oxygen fuel and its corrosion behavior in static lead–bismuth eutectic alloy

The Fe_49.7Cr₁₈Mn_1.9Mo_7.4W_1.6B_15.2C_3.8Si₂ amorphous coating was deposited on T91 steel substrate by using the high-velocity oxygen fuel (HVOF) spray technique to enhance the corrosion resistance of T91 stainless steel in liquid lead–bismuth eutectic (LBE). The corrosion behavior of the T91 steel and coating exposed to oxygen-saturated LBE at 400°C for 500 h was investigated. Results showed that the T91 substrate was severely corroded and covered by a homogeneously distributed dual-layer oxide on the interface contacted to LBE, consisting of an outer magnetite layer and an inner Fe–Cr spinel layer. Meanwhile, the amorphous coating with a high glass transition temperature (T_g = 550°C) and crystallization temperature (T_x = 600°C) exhibited dramatically enhanced thermal stability and corrosion resistance. No visible LBE penetration was observed, although small amounts of Fe₃O₄, Cr₂O₃, and PbO were found on the coating surface. In addition, the amorphicity and interface bonding of the coating layer remained unchanged after the LBE corrosion. The Fe-based amorphous coating can act as a stable barrier layer in liquid LBE and have great application potential for long-term service in LBE-cooled fast reactors.