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Electroplating zinc transition layer for electroless nickel plating on AM60 magnesium alloys 总被引:1,自引:0,他引:1
Electroplating zinc coating as transition layer of electroless nickel plating on AM60 magnesium alloys was investigated. The zinc film can be deposited in a pyrophosphate bath at 50-60 ℃ under current density of 0.5-1.5 A/dm^2. A new fore treatment technology was applied by acid cleaning with a solution containing molybdate and phosphorous acid, by alkaline cleaning in a bath containing molybdate and sodium hydroxide. The subsequent electroless plating was carried out in nickel sulfate bath. The SEM observation shows that the deposition is uniform and compact. The polarization curve measurements show that the corrosion potential of the zinc plating in 3.5% NaCl is about -1.3 V(vs SCE) which is noble than that of magnesium substrate. The zinc eleetroplating can be applied as the pretreatment process for electroless nickel plating on magnesium alloys. 相似文献
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Corrosion behavior of AZ91 magnesium alloy in simulating acid rain under wet-dry cyclic condition was investigated.The results show that corrosion potential shifts positively and the corrosion current density decreases at low wet-dry cyclic time.Further increase of the cyclic time results in the negative movement of corrosion potential and the increase of current density.SEM observation indicates that corrosion occurs only inαphase,βphase is inert in corrosive medium,and the corrosion of AZ91 magnesium a... 相似文献
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以环境友好型钼酸盐化学转化膜替代传统高污染的铬酸盐钝化膜,是镀锌层钝化工艺技术的发展方向。随着累计处理热浸镀锌钢板面积的增加,新制的钼酸盐钝化处理液会逐渐失去钝化能力。探索出一种能够使失效的处理液恢复钝化性能的氧化型添加剂,研究了添加剂对失效钝化液性能恢复的影响。用电化学极化曲线研究了转化膜的腐蚀行为。结果表明,添加剂的补加使极化曲线阳极分支重新出现钝化特征,即失效钝化液恢复钝化能力。扫描电子显微镜观察表明,补加添加剂后形成的转化膜表面平整、均匀。X-射线能量分析表明,转化膜中含有Mo、P、O和Zn等元素。经24 h盐雾试验表面转化膜具有较好的抗盐雾腐蚀能力。 相似文献
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目的 增强双极板在质子交换膜燃料电池(PEMFC)工作条件下的耐腐蚀性能.方法 以1-乙基-3-甲基咪唑硫酸乙酯(EMIES)离子液体作为聚合反应电解质,采用循环伏安法在316L不锈钢(SS)上电聚合聚苯胺(PANI)薄膜制备PANI/316L SS双极板.采用SEM观察表面形貌,采用FTIR分析官能团结构,采用XPS分析元素组成和键合状态.采用恒电位法控制PANI/316L SS电位分别为0.5、0.6、0.7 V(vs.SCE)以模拟PEMFC阴极电位,测量恒电位极化后开路电位、极化曲线和电化学阻抗谱(EIS)的变化.结果 PANI膜均匀平整局部有微裂纹.FTIR显示有苯环、醌环、S=O和—COOH伸缩振动.XPS表明PANI膜含有C、N、O和S等元素.PANI/316L SS极化曲线在钝化区内电流密度波动较大,EIS的Nyquist图由高频容抗弧和低频直线构成,容抗弧半径随着极化电位的升高而增大.结论 PANI为中间氧化态结构,EMIES阴离子(CH3CH2SO4–)和草酸阴离子(HOOC-COO–)在PANI分子链中均有掺杂.在PEMFC阴极工作电位下PANI/316L SS处于阳极极化状态,电位对PANI/316L SS的耐蚀性影响显著,在0.6 V下PANI/316L SS呈现很好的耐蚀性,电位升高至0.7 V时,发生PANI过度氧化,导致"对阴离子"脱掺杂,使PANI/316L SS的导电性和耐蚀性下降. 相似文献