Ni-Cr合金在3.5%NaCl溶液中的腐蚀行为

Corrosion behavior of Ni-Cr alloys in 3.5% NaCl solution

针对Ni-Cr合金在含Cl离子溶液中的腐蚀行为,利用M273型电化学测试系统,测试了纯Ni金属、Ni-10Cr与Ni-20Cr合金在3.5%NaCl溶液中的动电位极化曲线.采用XPS测试技术分析了3种材料形成钝化膜的组成成分,并对材料的点腐蚀机理进行了探讨.实验结果表明:随着合金中w(Cr)的增大,合金的自腐蚀电位提高,钝化区间由200mV增大到600mV,钝化膜以由水合Ni的氧化物或氢氧化物组成为主,转变为以Cr的氧化物或氢氧化物组成为主,点蚀击破电位由-0.1V提高到+0.38V,明显提高了合金的耐蚀性能.因此,在含Cl-离子腐蚀溶液介质中,Ni-Cr合金体系的耐点蚀能力与其w(Cr)密切相关.

In order to investigate the corrosion behavior of Ni-Cr alloys in Cl^- containing solution, the potentiodynamic polarization curves of pure Ni as well as Ni-10Cr and Ni-20Cr alloys were measured in 3.5% NaCl solution using M273 electrochemical test system. The constituent of the surface passive film formed on three materials was analyzed by XPS testing technology, And the pitting corrosion mechanism of the materials was discussed. The results show that with increasing the Cr content, the self-corrosion potential of the Ni-Cr alloy increases and the passivation range gets incerased from 200 mV to 600 mV. The passive film is mainly composed of Cr containing oxides or hydroxides instead of hydrated Ni containing oxides or hydroxides. The pitting breakdown potential increases from -0. 1 V to ＋ 0. 38 V. It is suggested that the pitting corrosion resistance of the Ni-Cr alloys in Cl^- containing solution is closely related to the Cr content.