摘要
目的提高镁锂合金微弧氧化陶瓷层的耐蚀性能。方法在镁锂合金表面原位生长包覆GO的复合陶瓷层。用SEM观察陶瓷层的表面形貌和截面形貌,用XRD和XPS分别检测陶瓷层的物相及成分组成,并采用动电位极化曲线方法和浸泡试验研究陶瓷层在3.5%NaCl溶液中的腐蚀过程。结果添加GO制备的复合陶瓷层表面微孔部分堵塞,致密度较高,但厚度略低,其陶瓷层物相主要包括SiO2、Mg2Si O4和Mg O。微弧氧化陶瓷层的自腐蚀电流密度较镁锂合金基体降低了3个数量级,其极化电阻值则相应地升高了2个数量级。而加入GO所制备的复合陶瓷层的腐蚀电流密度仅为陶瓷层的57%,其极化电阻值约为7.69×104Ω·cm^2,是微弧氧化陶瓷层的2.5倍。浸泡在NaCl溶液中的复合陶瓷层能够长时间维持较低的腐蚀电流密度。结论 GO添加剂能够堵塞微弧氧化陶瓷层表面部分微孔,增加陶瓷层的致密性,进而阻止腐蚀性离子的渗入,可有效提高陶瓷层的耐腐蚀性能。
The work aims to improve the corrosion resistance of micro-arc oxidation coatings on Mg-Li alloy. GO-containing composite coating was in-situ fabricated on Mg-Li alloy. Surface and cross section morphologies of the prepared coatings were observed by SEM. The composition and crystal structure were identified by XPS and XRD, respectively. Meanwhile, the corrosion behaviors of the prepared samples were studied by the potentiodynamic polarization and immersion test in 3.5%NaCl aqueous solution. The GO-containing composite coating possessed blocked pores, evidently higher compactness and relatively lower thickness and mainly consisted of SiO2, Mg2SiO4, and MgO phases. The corrosion current density of GO-free coating decreased by two orders of magnitude and the polarization resistance was correspondingly increased by two orders of magnitude, respectively. However, the corrosion current density of the GO-containing coating was only 57% of that of the GO-free coating. Besides, the polarization resistance of the GO-containing was estimated at up to 7.69×104 Ω·cm^2, which was approximately 2.5 times the value of Rp for the GO-free coating. The composite coating immersed in NaCl solution could effectively maintain a low corrosion current density value for a long time. The GO additive can seal some micropores on the surface of MAO coating and increase the coating’s compactness to prevent corrosive ions from permeating into the substrate through discharge channels, thereby enhancing corrosion resistance of the MAO coating.
作者
张志莲
张玉林
陈飞
ZHANG Zhi-lian;ZHANG Yu-lin;CHEN Fei(School of Mechanical Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617, China;School of Materials Science and Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617, China;Beijing Key Lab of Special Elastomeric Composite Materials, Beijing Institute of Petrochemical Technology, Beijing 102617, China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2019年第6期306-313,345,共9页
Surface Technology
基金
大学生研究训练计划项目(2017J00174,2017J00175)~~
关键词
镁锂合金
氧化石墨烯
微弧氧化
致密性
耐蚀性
Mg-Li alloy
graphene oxide
micro-arc oxidation
compactness
corrosion resistance
