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采用动电位极化、电化学阻抗及Mott-Schottky技术研究了316L不锈钢在pH值分别为4,7和11的硼酸溶液中钝化膜的电化学行为,并对钝化膜成分进行了X射线光电子能谱分析。结果表明:316L不锈钢在酸性、中性和碱性硼酸溶液中均能形成稳定的钝化膜,且随p H值增加钝化电位区间减小,过钝电位显著下降。碱性硼酸溶液中316L不锈钢过钝电流显著增加。钝化膜完整性在中性硼酸溶液中最好,酸性溶液中最差。MottSchottky曲线结果表明,在酸性环境中随着电位的升高,钝化膜由n型向p型转变;在中性和碱性环境中,钝化膜半导体类型分别为n型和p型。这是由于随p H值增加,Cr的氢氧化物消失,钝化膜中Fe由Fe O(OH)转变为Fe_3O_4;在碱性环境下钝化膜中Cr_2O_3含量减少导致耐蚀性下降。
The electrochemical behavior of the passivation film of 316L stainless steel in boric acid solutions with pH values of 4, 7 and 11 respectively was studied by potentiodynamic polarization, electrochemical impedance and Mott-Schottky technique. The passivation film composition was characterized by X-ray Photoelectron spectroscopy. The results show that 316L stainless steel can form a stable passive film in acidic, neutral and basic boric acid solutions. With the increase of p H, the passivation potential decreases and the blunted potential decreases significantly. 316L stainless steel in the basic boric acid solution dull current increased significantly. Passivation film integrity in the best neutral boric acid solution, the worst acidic solution. The MottSchottky curve shows that the passivation film changes from n-type to p-type with increasing potential in acidic environments. The n-type and p-type semiconductor semiconductors are in the neutral and alkaline environments, respectively. This is due to the fact that as the value of p H increases, the hydroxide of Cr disappears and the amount of Fe in the passivation film changes from Fe O (OH) to Fe 3 O 4. The reduction of Cr 2 O 3 content in the passivation film leads to a decrease of corrosion resistance.