氯化钾镀锌层表面不同颜色钝化膜的结构及耐蚀性分析  

Microstructure and corrosion resistance analysis of different colored passive films on the surface of zinc coating obtained from potassium chloride system

作　　者：焦莎 刘燕 张晓斌 张涛 赵超 王帅星[4] 杜楠[4] Jiao Sha;Liu Yan;Zhang Xiaobin;Zhang Tao;Zhao Chao;Wang Shuaixing;Du Nan(Tianjin Key Laboratory of Fastening Technology,Tianjin 300300,China;Aerospace Precision Production Co.,Ltd.,Tianjin 300300,China;The Second Military Representative Office of Beijing Military Representative Bureau of Air Force Equipment Department in Tianjin,Tianjin 300300,China;School of Materials Science and Engineering,Nanchang Hangkong University,Nanchang 330063,China)

机构地区：[1]天津市紧固连接技术企业重点实验室,天津300300 [2]航天精工股份有限公司,天津300300 [3]空军装备部驻北京地区军事代表局驻天津地区第二军事代表室,天津300300 [4]南昌航空大学材料科学与工程学院,江西南昌330063

出　　处：《电镀与精饰》2025年第1期29-36,共8页Plating & Finishing

基　　金：天津市紧固连接技术企业重点实验室开放课题项目(TKFL2022-02-B-02)。

摘　　要：钝化是提高电镀锌层防护性能的关键工艺,但镀锌钝化膜往往由于工艺参数差异造成一些色差。对此,论文通过扫描电子显微镜、X射线衍射、动电位极化曲线及电化学阻抗谱较为系统地分析了不同颜色钝化膜在微观结构及耐蚀性方面的差异。结果表明,氯化钾镀锌层呈银白色,镀层呈随机取向分布、晶粒尺寸约为35~40 nm,其自腐蚀电流密度高达4.425×10^(-5)A/cm^(2)。钝化处理后镀锌层表面呈网状微裂纹结构、耐蚀性显著提升,但钝化体系及后续干燥方式对钝化膜颜色、微观结构及耐蚀性有较大影响。低铬体系钝化膜整体偏绿、膜层主要为Cr(Ⅲ)的化合物;60℃烘干后钝化膜呈绿紫色,网格结构更为规整,但表面仍存在孔洞。三酸体系钝化膜同时存在Cr(Ⅲ)和Cr(Ⅵ)的化合物、颜色更接近彩虹色,网状裂纹数量多且密集。偏绿和绿紫色的低铬钝化膜耐蚀性接近,但明显不如彩虹色的三酸钝化膜。Passivation is a key process to improve the protective performance of zinc plating,but the passive film of zinc plating often causes some color differences due to the differences in process parameters.In this paper,the differences in microstructure and corrosion resistance of different colored passive films are systematically analyzed through scanning electron microscopy,X-ray diffraction,potentiodynamic polarization curve,and electrochemical impedance spectroscopy.The results showed that zinc coating obtained from potassium chloride system is silver white with a random orientation distribution and a grain size of about 35~40 nm,the corrosion current density is as high as 4.425×10^(-5) A/cm^(2).After passivation treatment,the surface of zinc coating exhibits a network like micro-crack and the corrosion resistance is significantly improved.However,the passivation system and subsequent drying methods have a significant impact on the color,microstructure,and corrosion resistance of passive film.The passive film obtained in low chromium bath is generally green,and is mainly composed of Cr(III)compounds.After drying at 60,the passive film appears green purple with a more regular grid structure,℃but pores are still present on the surface.The tri-acid passive film contains both Cr(III)and Cr(VI)compounds,which is closer to rainbow color and has many and dense network cracks.Moreover,the corrosion resistance of low chromium passive films with green and green purple hues is similar,but is significantly inferior to that of rainbow colored tri-acid passive film.

关 键 词：镀锌 钝化膜 颜色 微观结构 耐蚀性 

分 类 号：TG174.453[金属学及工艺—金属表面处理]