低碳钢表面Fe-Ni合金层的制备及耐腐蚀性能

Preparation and Corrosion Resistance Performance of Fe-Ni Alloy Coating on Surface of Mild Steel

以纳米NiO粉体为Ni源,通过热扩渗在低碳钢表面制备Fe-Ni合金层,研究了处理温度对Fe-Ni合金层表面状态、结构和耐腐蚀性能的影响。结果表明:处理温度高于800℃可在低碳钢表面形成厚度20—25μm、表面Ni含量(原子分数)高于25%、与低碳钢基底形成了冶金结合的Fe-Ni合金层,处理温度不低于900℃时Fe-Ni合金层为单一α-Fe固溶体相。随着处理温度的提高,Fe-Ni合金层在质量分数为3.5%NaCl溶液中的耐腐蚀性能提高。在3.5%的NaCl溶液中Fe-Ni合金层的Ecorr均较低碳钢的Ecorr发生了正移,Fe-Ni合金层的icorr均较低碳钢的icorr有不同程度的降低,Fe-Ni合金层的电化学阻抗均大于低碳钢的电化学阻抗。

Fe-Ni alloy coatings were prepared on the surface of mild steel by means of thermal diffusion, using nano-NiO powder as the source of Ni element. The effects of treatment temperature on surface state, structure and corrosion resistance of the Fe-Ni alloy coatings were investigated. The result shows that： when the treatment temperature was higher than 800 ℃, 20-25 pm Fe-Ni alloy coatings formed and Ni content （atomic fraction） were higher than 25% on the surface, the coating and the substrate was integrated to metallurgy structure. When the treatment temperature was higher than 900 ℃, Fe-Ni alloy structure became single a-Fe solid solution phase. The corrosion resistance of Fe-Ni alloy coatings increased with the treatment temperature from 700 to 1000 ℃. In contrast with mild steel in 3.5% NaCI solution, the Fe-Ni alloy coatings have more positive corrosion potential, much lower corrosion current density. The electrochemical impedance of Fe-Ni alloy coatings was also bigger than that of mild steel in 3.5%NaCI solution.