哌啶作为AISI304不锈钢孔蚀缓蚀剂的电化学研究

AN ELECTROCHEMICAL INVESTIGATION ON THE INHIBITION EFFECT OF PIPERIDINE FOR TYPE 304 STAINLESS STEEL IN NaCl MEDIA

选用哌啶作为ＡＩＳＩ３０４不锈钢在中性氯化钠介质中的孔蚀缓蚀剂。运用稳态阳极极化曲线和Ｐ－Ｇ瞬态响应测试研究哌啶的缓蚀作用。研究结果表明哌啶（ＰＤ）对氯化钠溶液中３０４不锈钢孔蚀的发生有相当强的抑制作用；１１００小时的长时间测试证实哌啶能明显阻滞孔蚀的发展过程。哌啶通过竞争吸附机制起缓蚀作用。在缓蚀剂分子与侵蚀性阴离子的浓度比高于“临界浓度比”的体系，哌啶的缓蚀作用明显优于浓度低于“临界比”的体系。所研究体系的“临界浓度比”为ＰＤ：Ｃｌ－＝１：５０～８０（摩尔比）。初步分析了高于“临界浓度比’体系的缓蚀剂阳极脱附及其对缓蚀性能的影响。

The inhibition effect of piperidine (PD) for pitting initiation and propagation of AISI 304 stainless steel in NaCl solution of various concentrations was investigated by potentiodynamic anodic polarization and P-G transient inhibition measurements. In order to evaluate the long-term inhibition performance of PD, the pitting breakdown potentials of the system, 304 SS/0.5 mol/L NaCl + 5 mmol/L PD, were measured continuously for 1100 hours. The results showed that the pitting propagation was inhibited to a certain extent. The possible inhibition mechanism of PD for pitting initiation and propagation was discussed according to the competitive adsorption theory. In addition, a new idea of 'Critical Ratio' of PD concentration to Cl- concentration was suggested for the judgement of inhibition effect. For the system in which the ratio of PD concentration to Cl- concentration was greater than the 'Critical Ration', the inhibition role was more satisfactory than that in which the ratio is less than the criterion. The anodic desorption of the inhibitor was discussed preliminarily.