钝化液中的杂质离子对镀锡板钝化膜性能的影响

Influence of impurity ions in passivation solution on performances of passivation film on tinplate

通过电位-时间曲线、Tafel曲线测试和中性盐雾试验,研究了镀锡板铬酸盐体系钝化液中硫酸根、铁、锡等杂质离子对钝化膜铬含量和耐蚀性的影响。结果表明,上述3种杂质离子的存在会导致钝化膜的铬含量与耐蚀性下降。当SO_4^(2-)、Fe^(2+)和Sn^(2+)的含量分别超过10、7和11 mg/L时,钝化膜的铬含量与耐蚀性明显下降。在实际生产中,应将钝化液中这3种杂质离子的含量控制在上述质量浓度以下。可通过加强酸洗与带出回收后的水洗,加快淬水液更新,加强钝化液的过滤,及时更换钝化阳极,以及保证钝化液原材料的纯度等方法来控制杂质离子的含量。

The influence of sulfate ion, ferric ion and tin ion in passivation solution on chromium content and corrosion resistance of passivation film was studied by determination of potential vs. time curves and Tafel curves and neutral salt spray test. It is indicated that the existence of the said three kinds of impurity ions reduces the chromium content and corrosion resistance of passivation film. A sharp decrease of chromium content and corrosion resistance of passivation film occurs when the content of SO2/, Fe2＋ and Sn2＋ exceeds 10, 7 and 11 mg/L, respectively. In practical production, the concentration of the three impurity ions in passivation solution should be controlled below the mass concentrations mentioned above. Some control methods are as follows： enhancing the water rinse after pickling and reclaiming of drag-out water, accelerating the renewal of quenching solution, enhancing the filtration of passivation solution, replacing the passivation anode in time, and ensuring the purity of raw materials for passivation solution.