pH值对车用AZ91B镁合金LDH/HPP膜组织和耐腐蚀性能的影响  

Effect of pH Values on Microstructure and Corrosion Resistance of LDH/HPP Film on Automotive AZ91B Magnesium Alloy

作　　者：李高磊[1] 朱学军[1] 孙胤胤 赵信 LI Gao-lei;ZHU Xue-jun;SUN Yin-yin;ZHAO Xin(College of Automobile,Henan Vocational And Technical College of Transportation,Zhengzhou 450000,China;Suzhou Automotive Research Institute,Tsinghua University,Suzhou 215000,China;Beijing Zhenmeng Magnesium Alloy Technology Co.,Ltd.,Beijing 100036,China)

机构地区：[1]河南交通职业技术学院汽车学院,河南郑州450000 [2]清华大学苏州汽车研究院,江苏苏州215000 [3]北京臻梦镁合金科技有限公司,北京100036

出　　处：《材料保护》2021年第9期96-100,共5页Materials Protection

基　　金：河南省高等学校青年骨干教师培养计划项目(2017GGJS242)资助。

摘　　要：目前关于有机磷酸(HPP)pH值对镁合金表面层状双羟基金属氧化物(LDH)膜的影响规律研究不多。为此,选择一步水热工艺处理镁合金试样使其表面生成LDH膜,通过有机磷酸完成LDH膜的表面结构转化,采用两步制备工艺得到LDH/HPP膜复合结构,并通过试验测试方法对其组织和腐蚀性能进行分析。研究结果表明:对试样表面进行有机磷酸处理后存在具有片状形态的水滑石微观结构。当有机磷酸溶液pH值达到6和8时,在LDH/HPP膜内检测到了MgHPO_(4)特征峰。相对于LDH膜,LDH/HPP膜腐蚀电位逐渐提高,腐蚀电流密度不断降低。pH为8的条件下,膜获得了最高腐蚀电位,腐蚀电流密度达到了最小,表现出了最优的耐腐蚀性能。各成膜试样都形成了一个高频容抗弧与低频容抗弧,未观察到感抗弧与扩散阻抗产生。以pH值为8的有机磷酸溶液进行处理时,膜获得了最大容抗弧半径。经过有机磷酸处理后,LDH/HPP膜获得了更大极化电阻,获得了更强的耐蚀性能。At present,there are few studies on the effect of pH value of organic phosphoric acid(HPP)on layered dihydroxy metal oxide(LDH)film on magnesium alloy surface.For this,the LDH film was formed on the surface of magnesium alloy samples by one-step hydrothermal treatment.Then,the surface structure of the LDH film was transformed by HPP to form the LDH/HPP film composite structure by a two-step preparation process.Furthermore,the microstructure and corrosion properties of LDH/HPP film were analyzed by experimental test methods.Results showed that the surface of the sample treated with HPP had the microstructures of hydrotalcite with flake shape.When the pH of HPP solution reached 6 and 8,the characteristic peak of MgHPO_(4) was detected in LDH/HPP film.Compared with LDH film,the corrosion potential of LDH/HPP film increased gradually,and the corrosion current density decreased.Under the condition of pH=8,the film had the highest corrosion potential,the corrosion current density reached the minimum,showing the optimal corrosion resistance.A high frequency capacitive reactance arc and a low frequency capacitive reactance arc were formed in each film sample,and inductive arc and diffusion impedance was not observed.The maximum capacitive reactance arc radius was obtained when the pH of HPP solution was 8.After the treatment of the HPP,the LDH/HPP film had greater polarization resistance and stronger corrosion resistance.

关 键 词：镁合金 LDH/HPP膜 耐腐蚀性 PH值 

分 类 号：TG174[金属学及工艺—金属表面处理]