Beneficial effects of CeO2 addition on microstructure and corrosion behavior of electrodeposited Ni nanocrystalline coatings
Beneficial effects of CeO2 addition on microstructure and corrosion behavior of electrodeposited Ni nanocrystalline coatings
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DOI：
10.1016/j.surfcoat.2013.07.070
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发表时间：
2013-11
影响因子：
5.4
通讯作者：
Xiaowei Zhou;Yifu Shen
中科院分区：
文献类型：
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作者：
Xiaowei Zhou;Yifu Shen
本文通过实验研究了添加ceo_2对纳米晶Ni涂层的微观结构和腐蚀行为的影响。采用超声辅助脉冲电沉积的新方法制备了改性瓦茨镍电解液镀层。利用电子扫描电镜和透射电镜观察了时效前后涂层的表面形貌和微观组织演变。采用电化学技术，结合XRD和XPS分析研究了其在5 wt.% HCl水溶液中的腐蚀行为。详细讨论了富铈钝化层的缓蚀机理。实验结果表明，通过650℃时效处理4 h，涂层中存在分布均匀的ceo2相，促进了弥散强化，从而实现了界面边界之间有效的结合连接，使微观组织更加致密。极化曲线和交流阻抗测量结果表明，ni - ceo2镀层的耐蚀性优于纯镍镀层。在5 wt.% HCl酸性水溶液中长期静态浸渍试验中，富ce相的溶解沉淀中释放出少量Ce3 +/4 +离子，起到缓蚀剂的作用。此外，电化学反应过程中产生的一些不溶性腐蚀产物有利于防止腐蚀表面受到Cl−离子的腐蚀攻击和扩散行为。
This paper presents an experimental study of the effects of CeO2addition on the microstructure and corrosion behavior of nanocrystalline Ni coatings. A novel method of ultrasound-assisted pulsed electrodeposition was used to prepare the coatings from a modified Watts-nickel electrolyte.Surface morphologies and micro-structural evolution of the coatings before and after aging treatments were characterized using E-SEM and TEM observations. Furthermore, electrochemical techniques attached with the XRD and XPS analysis were applied to study their corrosion behavior in a 5 wt.% HCl aqueous solution. The underlying mechanisms of corrosion inhibition resulted from the Ce-rich passive layer were discussed in detail. Experimental results indicated that the existence of well-distributed CeO2phase in the coatings promoted dispersion strengthening through a proper aging treatment at 650 °C for 4 h, thereby achieving an effective bonding link between interfacial boundaries for denser microstructure. According to the measured results from polarization curves and the AC-impedance measurements, it exhibited superior corrosion resistance of the Ni-CeO2coatings as compared to pure nickel. During the long-term static immersion tests in an acid 5 wt.% HCl aqueous solution, a small amount of Ce3 +/4 +ions was released from the dissolution–precipitation of a Ce-rich phase and served as the corrosion inhibitors. Furthermore, some insoluble corrosion products resulted from the process of electrochemical reactions were favorable for precluding the corroded surface from the corrosive attack and diffusion behavior by Cl−ions.