Synthesis of Local Corrosion Inhibitors and Establishment of Evaluation Technique for Their Inbibiting Effect by Alternate Method

本研究的目的是首次合成新型杂环有机化合物作为不锈钢、铝等的局部缓蚀剂，从结果来看，嘧啶类化合物是合成的杂环化合物中最有效的缓蚀剂。结果表明，在环的第二位具有含O或S的取代基的衍生物是最有效的。噻唑系统也是有效的，但不依赖于取代基。这些缓蚀剂吸附在金属表面，控制阳极和阴极的腐蚀反应。对于交流阻抗测量，采用FFT方法进行测量，因为可以在短时间内测量。因此，时间依赖性可以很容易地测量。在点蚀过程中，一个电阻分量在诱导期内变化显著，而在点蚀形成时则趋于恒定。因此，可以通过电阻值和点蚀诱导时间来评价缓蚀剂的缓蚀效果，说明FFT阻抗法是评价缓蚀剂的有效工具。

The purpouse of this study is firstly synthesis of new hetero-cyclic organic compounds as the inhibitors for local corrosions of stainless steel,aluminum and etc.,and is secondly development of the alternate impedance measurement for the evaluation of inhibition.From the results, pyrimidines were the most useful as inhibitors among the synthesized heterocycric compounds. It was found that their derivatives which had substitutional functions containing O or S at second place of a cycle is the most effective. A thiazole system was also effective but independent of substitutional plase. These useful inhibitors adsorbed on the metals and controled both anodic and cathodic corrosion reactions.For the alternate impedance measurement, FFT-mathod for measurement was employed, because of possibility to measure in a short time. Therfore, time dependence could be easily measured. In the process of pitting, a resistance component was remarkably changing during the induction time, but atained a constant value when pits were generated. Therfore, the inhibition effects of the compounds could be evaluated by the values of resiprocal resistance and induction time to pitting coud be estimated.In conclusion, FFT method for impedance measurement was a powerful tool for evaluation of inhibitors.