林碧兰.铝合金表面钼酸盐改进植酸转化膜的耐蚀性能[J].表面技术,2016,45(3):115-119. LIN Bi-lan.Corrosion Resistance of Phytic Acid Conversion Coating Modified by Molybdate on Aluminum Alloy[J].Surface Technology,2016,45(3):115-119 |
铝合金表面钼酸盐改进植酸转化膜的耐蚀性能 |
Corrosion Resistance of Phytic Acid Conversion Coating Modified by Molybdate on Aluminum Alloy |
投稿时间:2016-01-21 修订日期:2016-03-20 |
DOI:10.16490/j.cnki.issn.1001-3660.2016.03.019 |
中文关键词: 铝合金 耐蚀性 植酸 钼酸盐 转化膜 |
英文关键词:aluminum alloy corrosion resistance phytic acid molybdate conversion coating |
基金项目:国家自然科学(51408517) |
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中文摘要: |
目的 通过钼酸钠(SM)添加剂、SM前处理、SM后处理三种方案对铝合金表面植酸转化膜进行改进研究,以进一步提高其耐蚀性。方法 通过动电位极化测试研究改进后铝合金在3.5wt.% NaCl溶液中的耐蚀性。结果 随着SM添加剂浓度的增加,铝合金表面植酸转化膜的耐蚀性先增强再减弱,SM浓度为30 g/L时的腐蚀保护效率Pe最大、达95.5%,而不含SM时的Pe仅为86.8%。pH值太大(pH8.0)或太小(pH3.0)都不利于形成耐蚀性更好的膜层,pH为6.0时的Pe达98.6%。SM后处理会严重影响植酸转化膜的耐蚀性,腐蚀电流密度jcor大幅增大;SM前处理可提高植酸转化膜的耐蚀性,Pe达98.2%;SM前处理与添加剂同时应用时,植酸转化膜耐蚀性提高幅度更显著,jcor仅为0.042 μA/cm2、降低了两个多数量级,极化电阻Rp达222 kΩ?cm2,Pe达99.5%。结论 SM添加剂和SM前处理均可明显提高铝合金表面植酸转化膜的耐蚀性,且复合作用时的效果更显著,而SM后处理不能提高铝合金表面植酸转化膜的耐蚀性。 |
英文摘要: |
Objective To further enhance the corrosion resistance of phytic acid conversion coating on aluminum alloy, sodium molybdate (SM) additives, SM pre-treatment and SM post-treatment were applied to modify the process. Methods The corrosion resistance of the modified aluminum alloy in 3.5wt.% NaCl solution was investigated through dynamicpotential polarization test. Results With an increase in concentration of SM additives, the corrosion resistance of phytic acid conversion coating first increases and then decreases, and the corrosion protection efficiency Pe is largest, about 95.5% when SM was 30 g/L, while that is 86.8% when it was without SM additives. For pH6.0 the Pe value reaches to 98.6%, while a larger or a smaller pH (i.e. pH8.0 or pH6.0) is not beneficial to form a more anti-corrosive coating. However, the corrosion resistance of phytic acid conversion coating is seriously impaired by SM post-treatment, and the corrosion current density jcor is substantially increased. SM pretreated can enhance the corrosion resistance of phytic acid conversion coating, and Pe is 98.2%. When SM pretreatment and SM additives were applied meanwhile, the corrosion resistance of phytic acid conversion coating is improved most significantly, jcor is merely 0.042 μA/cm2, decreasing for about two orders of magnitude; the polarization resistance Rp is 222 kΩ•cm2, and Pe is highly up to 99.5%. Conclusion The corrosion resistance of phytic acid conversion coating on aluminum alloy can be largely enhanced by SM additives and SM pre-treatment, and the inhibition efficiency is more outstanding when these two modified schemes were applied simultaneously. However, SM post-treatment can not improve the corrosion resistance of phytic acid coating on aluminum alloy. |
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