超音速电弧喷涂NiAl复合涂层的电化学行为研究

发布时间：2019-02-09 18:02

【摘要】：目的研究NiAl复合涂层在腐蚀环境下的腐蚀行为及其失效机理,为其在工程中的实际应用提供理论依据。方法采用超音速电弧喷涂技术在20#钢基体表面制备了NiAl复合涂层,在此基础上对涂层的组织结构进行了表征,并对涂层与基体在3.5%NaCl溶液中的极化行为和交流阻抗谱行为进行了对比研究。结果 NiAl复合涂层的表层主要由Ni固溶体、NiAl金属间化合物和少量通过孔隙扩散到表层的Al组成。涂层呈典型的层状结构,结合较致密,表层(Ni)的孔隙率为5.3%,底层(Al)的孔隙率为4.4%。NiAl复合涂层的自腐蚀电位低于基体的自腐蚀电位,能起到良好的阴极保护效果。在测试初期,由于涂层厚度高达380μm,腐蚀介质通过涂层中存在的微裂纹和孔隙进入涂层内部,涂层快速消耗,形成较少的不溶性腐蚀产物,涂层阻抗较小,腐蚀速率较快。随腐蚀时间延长,不溶性腐蚀产物逐渐在孔隙内堆积,涂层内的极化电阻迅速增大,起到延缓腐蚀的作用。结论 NiAl复合涂层更好地发挥了Ni的耐蚀作用和Al的钝化保护作用,结合了两者的长处,表现出更好的耐蚀性能。涂层的自封闭作用是涂层阻抗值增加的主要原因。
[Abstract]:Aim to study the corrosion behavior and failure mechanism of NiAl composite coating in corrosion environment, and to provide theoretical basis for its practical application in engineering. Methods NiAl composite coatings were prepared on 20 # steel substrates by supersonic arc spraying, and the microstructure of the coatings was characterized. The polarization behavior and AC impedance spectrum behavior of the coating and substrate in 3.5%NaCl solution were studied. Results the surface layer of NiAl composite coating was mainly composed of Ni solid solution, NiAl intermetallic compound and a small amount of Al diffused through pores to the surface layer. The surface (Ni) porosity of the coating is 5.3 and the porosity of the bottom (Al) composite coating is lower than the self-corrosion potential of the 4.4%.NiAl composite coating. Can play a good cathodic protection effect. At the beginning of the test, because the thickness of the coating is up to 380 渭 m, the corrosion medium enters the coating through the microcracks and pores in the coating, and the coating is consumed rapidly, resulting in less insoluble corrosion products, lower coating impedance and faster corrosion rate. With the increase of corrosion time, the insoluble corrosion products gradually accumulate in the pores, and the polarization resistance in the coating increases rapidly, which plays the role of delaying corrosion. Conclusion the composite coating of NiAl has better corrosion resistance of Ni and passivation protection of Al, and combines the advantages of both, and shows better corrosion resistance. The self-sealing effect of the coating is the main reason for the increase of the coating impedance value.
【作者单位】：西安石油大学材料科学与工程学院;
【基金】：陕西省重点学科专项资金资助项目(ys37020203) 西安石油大学优秀硕士学位论文培育项目资助(2015yp140512)~~
【分类号】：TG174.4

【参考文献】