王楠,周勇.超音速电弧喷涂NiAl复合涂层的电化学行为研究[J].表面技术,2017,46(2):184-188.
WANG Nan,ZHOU Yong.Electrochemical Behavior of NiAl Composite Coating by Supersonic Arc Spraying[J].Surface Technology,2017,46(2):184-188 |
| 超音速电弧喷涂NiAl复合涂层的电化学行为研究 |
| Electrochemical Behavior of NiAl Composite Coating by Supersonic Arc Spraying |
| 投稿时间：2016-09-12 修订日期：2017-02-20 |
| DOI：10.16490/j.cnki.issn.1001-3660.2017.02.030 |
| 中文关键词: 超音速电弧喷涂 NiAl复合涂层 极化 电化学阻抗 |
| 英文关键词:supersonic speed arc spraying NiAl composite coating polarization electrochemical impedance |
| 基金项目: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） |
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| 中文摘要: |
| 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380 μm，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。 |
| 英文摘要: |
| The work aims to provide a theoretical basis for practical application to engineering by studying the corrosion behavior and failure mechanism of NiAl composite coating in corrosive environment. NiAl composite coating was prepared on 20# steel substrate by virtue of supersonic arc spraying technology. On this basis, organizational structure of the coating was characterized, and comparative study was performed to explore polarization behavior and EIS behavior of coating and 20 steel substrate in 3.5% NaCl solution. The surface layer of NiAl composite coating was mainly composed of Ni solid solution, NiAl intermetallic compound and few Al diffusing into the surface of the composition through pores. The coating was a typical dense layered structure, of which the porosity of surface layer (Ni) was 5.3% while that of base layer (Al) was 4.4%. The self-corrosion potential of NiAl composite coating was lower than that of the substrate, hence it could play favorable cathodic protection. During early test, corrosive medium pored entered the internal coating through microcracks and pores in the coating since thickness of the composite coating was up to 380 μm. The coating was consumed quickly and few insoluble corrosion products were produced. Coating impedance was lower and corrosion rate was smaller. With the extension of corrosion time, insoluble corrosion products gradually accumulated in the pores and the polarization resistance increased rapidly, playing a role in delaying corrosion. NiAl composite coating exhibits better corrosion resistance after combining the corrosion effect of Ni and the passivation effect of Al. The increase of coating impedance is mainly due to self-sealing effect of the coating. |
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