Nb质量分数对Al⁃15Si⁃xNb涂层组织与耐蚀性能的影响

Effect of Nb Content on Microstructure and Corrosion Resistance of Al⁃15Si⁃xNb Coating

彭贤民 林成 郭丽丽 史艳华 乔忠立 林丽彬

Xianmin Peng Cheng Lin Lili Guo Yanhua Shi Zhongli Qiao Libin Lin

辽宁石油化工大学 机械工程学院，辽宁 抚顺 113001 锦州锦恒汽车安全系统股份有限公司，辽宁 锦州 121007

School of Mechanical Engineering，Liaoning Petrochemical University，Fushun Liaoning 113001，China Jinzhou Jinheng Safety System of Automotive Co. ，Ltd. ，Jinzhou Liaoning 121007，China

以Al?15Si?xNb涂层为研究对象，探究了Nb质量分数对涂层显微组织结构和耐蚀性能的影响规律。采用金相显微镜观察涂层的组织形貌，运用XRD分析涂层的物相组成，应用电化学实验方法（包括开路电位、阻抗谱、极化曲线）表征并讨论了涂层在质量分数为3.5%的NaCl溶液中的腐蚀行为。结果表明，Al?15Si?xNb涂层主要由α?Al、初生Si、共晶Si组成，在涂层中加入Nb元素后生成少量的NbAl3相和Nb5Si3相；Nb元素的加入促进异质形核，较明显地改变涂层的组织分布；Al?15Si?10Nb涂层中的组织更细小且分布更均匀，均匀分布的α?Al、初生Si和共晶Si构成众多均匀分布的腐蚀微电池，促进α?Al阳极反应，使涂层表面生成的Al2O3氧化膜更加连续；Al?15Si?xNb涂层的极化曲线具有类钝化特征，其中Nb质量分数为10%时涂层的自腐蚀电位和点蚀电位较高，产物膜电阻较大，维钝电流密度较低，具有更好的耐腐蚀性能。

The Al?15Si?xNb coating was used as the research object to explore the effect of Nb content on the microstructure and corrosion resistance of the coating. The microstructure of the coating was observed by metallographic microscope, the phase composition of the coating was analyzed by XRD, and the corrosion behavior of the coating in 3.5% NaCl solution was characterized and discussed by electrochemical experimental methods (including open circuit potential, impedance spectrum analysis and polarization curve analysis). The results show that the Al?15Si?xNb coating is mainly composed of α?Al, primary Si and eutectic Si. A small amount of NbAl3 phase and Nb5Si3 phase are formed after Nb element is added to the coating; The addition of Nb promoted heterogeneous nucleation and significantly changed the microstructure distribution of the coating. The microstructure of Al?15Si?10Nb coating has a homogeneous distribution. Uniformly distributed α?Al, primary Si and eutectic Si will form many uniformly distributed corrosion micro?battery. It can promote Al anodic reaction and make the Al2O3 oxide film formed on the coating surface more continuous. The polarization curve of Al?15Si?xNb coating has passivation like characteristics. When 10% Nb is used, the self?corrosion potential and pitting potential of the coating are higher, the product film resistance is larger, and the dimensional passivation current density is lower. Therefore, Al?15Si?10Nb coating has better corrosion.

辽宁省教育厅科学研究经费项目(L2019023);辽宁石油化工大学引进人才科研启动基金项目(2019XJJ?004)

10.12422/j.issn.1672-6952.2023.01.009