摘要
为提高镀锌层的耐蚀性,以氟钛酸钾、双氧水、硝酸为辅助成分,制备了单宁酸钝化液,并对低碳钢上的碱性镀锌层进行了钝化处理。通过质量分数为5%的NaCl溶液浸泡试验,确定了最佳钝化液组成和钝化工艺条件为:单宁酸40g/L,HNO35mL/L,氟钛酸钾10g/L,H2O260mL/L,温度25°C,时间20～30s。采用扫描电镜研究了钝化膜的形貌;通过分析塔菲尔曲线和电化学阻抗谱,研究了钝化膜的耐蚀性。结果表明:锌镀层经钝化后出现白锈的时间长达120h;锌镀层表面生成致密的钝化膜;与镀锌基体相比,钝化后的镀锌层腐蚀电流明显降低,腐蚀电位、腐蚀电阻明显增大。单宁酸钝化膜有效抑制了镀锌层腐蚀的阳极过程。
To improve the corrosion resistance of zinc coating,low-carbon steel substrate coated by alkaline zinc plating process was passivated in tannic acid system using potassium fluotitanate,hydrogen peroxide and nitric acid as the auxiliary agents. The composition of passivation bath and process parameters of passivation were optimized by immersion test in 5wt% NaCl solution. The optimal bath composition and process parameters are as follows：tannic acid 40 g/L,HNO3 5 mL/L,potassium fluotitanate 10 g/L,H2O2 60 mL/L,temperature 25 °C,and time 20-30 s. The surface morphology of passive film was analyzed by scanning electron microscopy,and the corrosion resistance was studied by Tafel polarization and electrochemical impendence spectroscopy. The results showed that no white rust appears on the surface of passivated zinc coating within 120 h and the obtained passive film is compact. The passive film is characterized with lower corrosion current,higher corrosion voltage and better corrosion resistance thanthe zinc coating,implying that the passive film prepared from tannic acid can effectively inhibit the anodic process of zinc coating corrosion.
出处
《电镀与涂饰》
CAS
CSCD
北大核心
2011年第8期32-35,共4页
Electroplating & Finishing
关键词
镀锌层
无铬钝化
单宁酸
耐蚀性
zinc coating
non-chromium passivation
tannic acid
corrosion resistance
