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运用电化学测量、ICP-AES分析和SEM形貌观测技术研究铪在Et4NBr为支持电解质的无水异丙醇与乙腈(ACN)溶液中的电化学腐蚀行为。结果表明,开路电位随着浸入时间的增加而不断变正,直到达到一个较稳定数值,开路电位的上升与表面氧化膜钝化有关。在线性极化曲线中接近腐蚀电位的阳极极化段未出现活性溶解,这是其表面自发形成钝化膜的结果,之后,电位继续增加,点蚀发生。SEM形貌图证明电极表面点蚀坑的存在。循环伏安曲线与恒电流测量可以确定点蚀电位(φ_(pit))和再钝化电位(φ_p)。φ_(pit)随着扫描速率的增加而增大,但随着温度、溴离子浓度和ACN浓度增加而减小,连续重复扫描会使φ_(pit)正移。诱导时间对于点蚀长大必不可少。阻抗谱表明,溶液电阻和电荷转移电阻随着ACN浓度升高而降低。
The electrochemical corrosion behavior of hafnium in Et4NBr as the supporting electrolyte in anhydrous isopropanol and acetonitrile (ACN) was studied by electrochemical measurements, ICP-AES and SEM. The results show that the open circuit potential increases continuously with the immersion time until a stable value is reached. The rise of the open circuit potential is related to the passivation of the surface oxide film. In the linear polarization curve, there is no active dissolution in the anodic polarization near the corrosion potential, which is the result of the spontaneous formation of a passivation film on the surface. After that, the potential continues to increase and pitting occurs. SEM topographs demonstrate the existence of pits on the electrode surface. Cyclic voltammetry and galvanostatic measurements determine the pitting potential (φ pit) and the re-passivation potential (φ_p). φ pit increases with increasing scan rate but decreases with increasing temperature, bromide ion concentration, and ACN concentration, and continuous repetition of sweeps results in a positive shift of φ pit. Induction time is essential for pitting growth. Impedance spectroscopy showed that solution resistance and charge transfer resistance decreased with increasing ACN concentration.