热浸镀锌层有机物-无机物复合钝化工艺优选及其性能

为了进一步提高热浸镀锌层钝化膜的耐蚀性能,针对目前无铬钝化多为独立体系的有机物钝化或无机物钝化的情况,运用有机物与无机物进行复合钝化。通过正交试验法确立了热浸镀锌层无色钝化工艺,采用单因素变量法、点滴试验、中性盐雾腐蚀试验及电化学测试技术,研究了复合钝化工艺参数对钝化膜外观和耐蚀性的影响。结果表明:最佳复合钝化工艺为40 g/L丙烯酸树脂,20 g/L硝酸钠,40 g/L硅酸钠,15 m L/L过氧化氢;p H值11,钝化时间30 s,温度30℃,恒温烘干;钝化膜的耐蚀性能接近于三价铬钝化。

Process Optimization and Performance Evaluation of Organic and Inorganic Composite Passive Film on Hot-Dip Galvanized Layer

In order to improve corrosion resistance of passive film on hot-dip galvanized layer,for the situation that current systems of chromiumfree passivating were mostly independent inorganic or organic system,the organic passivation and inorganic passivation were combined.The colourless passivation technology of hot-dip galvanized coating was optimized by orthogonal experiment method.Meanwhile,the single factor variable method,drop test,neutral salt spray corrosion test and electrochemical test were employed to study the influences of passivation technology parameters on the surface morphology and corrosion resistance of passive film.Results showed that the optimal passivation technology was 40 g/L acrylic resin,20 g/L sodium nitrate,40 g/L sodium silicate,15 mL/L hydrogen peroxide,pH =11,30 s of passivation time,30 ℃ of temperature and drying in constant temperature.The corrosion resistance of composite passive film was close to that of trivalent chromium passive film.