低氧分压预处理对镍基合金028耐蚀性的影响

摘要

对镍基合金Alloy028在900 C进行低氧分压预处理10 h,金相观察和硬度测试结果表明,预处理后析出物减少,组织得到细化,硬度明显提高.SEM、EDS及XRD分析比较试样表面微观形貌与结构特征表明,预处理后钝化膜形成元素Cr在表面发生富集,且部分形成由Cr2O3和NiCr2O4组成的氧化膜.极化曲线测试表明,预处理后合金的自腐蚀电位从-0.37 V正移至-0.25 V(SCE),腐蚀电流密度比空白试样显著降低.电化学阻抗测试表明,预处理试样的电荷转移电阻比空白试样提高一个数量级,膜电阻提高2倍多.%The pretreatment of nickel base alloy 028 at low oxygen partial pressure was carried out at 900 C for lOh. After the pretreatment, the microstructure of the nickel alloy 028 sample was refined, precipitation along with its boundaries decreased and its hardness increased. The Cr2O3 and NiC2O4 oxide films with continuously compact structural feature were formed primarily on the sample surface. They were examined by SEM, EDS and XRD. The polarization curve of the sample after the pretreatment indicated that its corrosion potential moved from -0. 25V to 0. 37 V(SCE), and corrosion current density obviously reduced compared with those of the control sample. The measurements of EIS showed that the charge transfer resistance after pretreatment rose by an order of magnitude and the film resistance reached 2 times or more compared with those of the control sample.