Ni-Cr-Mo-Nb超音速火焰喷涂层在模拟烟气中的热腐蚀行为

选用适量的Ni,Cr,Mo和Nb的配比,在20钢表面超音速火焰喷涂了Ni-Cr-Mo-Nb合金层,以期提高其耐蚀性。采用XRD,SEM/EDS技术对Ni-Cr-Mo-Nb合金层及其高温腐蚀产物成分、形貌进行了分析;对Ni-Cr-Mo-Nb合金层涂覆75%Na_2SO_4+25%NaCl(质量分数)混合熔盐后于600,650℃烟气中的热腐蚀行为进行了研究。结果表明:Ni-Cr-Mo-Nb合金层结构致密,孔隙率低;Ni-Cr-Mo-Nb合金层在涂覆75%Na2SO4+25%Na Cl盐膜后的烟气中600,650℃时先增重后失重,其腐蚀产物分为2层,外层富含Ni,内层富含Cr且S含量较高,具有良好的耐蚀性能。

Hot Corrosion Behavior in Simulated Flue Gas of Ni-Cr-Mo-Nb Coating Prepared by High Velocity Oxygen Fuel Spray

Ni-Cr-Mo-Nb alloy coating was prepared on 20 steel substrate by high velocity oxygen fuel spray,with choosing the appropriate ratio of Ni-Cr-Mo-Nb to improve the corrosion resistance of the material.XRD,SEM and EDS were employed to study compositions and structure of Ni-Cr-Mo-Nb alloy coating and high-temperature corrosion products.Moreover,the hot corrosion behavior of the prepared samples coated with a film of mixed salts 75％Na2SO4+25％NaCl (mass fraction) was investigated in simulated flue gas at 600 ℃ and 650 ℃,respectively.Results showed that the prepared Ni-Cr-Mo-Nb coating was dense with low porosity.The corrosion kinetics showed that mass gain of thesamples coated with a film of mixed salts 75 ％Na2SO4 + 25％NaCl at the beginning corrosion stage and subsequently mass loss occurred at 600 ℃ and 650 ℃.Moreover,the scale of corrosion products had duplex microstructure:the outer layer was rich in Ni,and the inner layer was rich in Cr and S.The Ni-Cr-Mo-Nb alloy coating exhibited good corrosion resistance in simulated flue gas.