电化学方法在不锈钢腐蚀研究中的应用现状及发展趋势

Current application and development trend in electrochemical measurement methods for the corrosion study of stainless steels

电化学手段可以实现对不锈钢材料的快速评价和腐蚀机理研究,因而受到广泛应用.在不锈钢耐蚀性评价方面,最常采用的电化学手段主要有腐蚀电位测试、交流阻抗测试、恒电位极化测试以及循环动电位极化测试.本文分别针对上述四种电化学方法在不锈钢耐蚀性评价上的应用情况进行了介绍,明确了各种检测方法的特点.腐蚀电位及交流阻抗测试是无损检测手段,可以满足长周期腐蚀监测需求;恒电位极化和循环动电位极化测试可以获得材料的极化特征参数,有利于对材料的腐蚀机理及耐蚀性进行评价.结合当前的不锈钢腐蚀研究现状,展望了电化学方法在腐蚀研究领域的发展趋势:未来电化学方法将更多作为腐蚀调控手段,需要结合其他检测技术实现对不锈钢腐蚀过程的精细分析.

Carbon steels are prone to a high level of corrosion when exposed to harsh environments.Stainless steels,having better corrosion resistance,are therefore,used in many applications to mitigate the high risk of failure due to corrosion.However,stainless steels are also not 100%corrosion-resistant;hence,they may suffer uniform corrosion,pitting corrosion,and/or corrosion cracking.It is,therefore,necessary to evaluate the corrosion resistance of stainless steel prior to its large-scale applications.The two main techniques used in studying the corrosion behavior of stainless steels are the immersion and electrochemical tests.Due to the high corrosion resistance of stainless steels,analyzing its corrosion behavior using the immersion test method takes a long period.Consequently,the application of the immersion test method is highly limited.The electrochemical methods are,therefore,widely used due to its faster rate of evaluation of corrosion behavior and mechanisms.The most commonly used electrochemical methods in the corrosion assessment of stainless steels include the corrosion potential test,AC impedance test,potentiostatic test,and cyclic polarization test.This paper introduced these four electrochemical methods of corrosion evaluation of stainless steels.The advantages and disadvantages of various detection methods were also clarified.Long-period corrosion monitoring can be achieved with the implementation of corrosion potential and AC impedance methods,due to their nondestructive features.The polarization characteristic parameters of materials can be obtained by analyzing the potentiostatic or potentiodynamic polarization results.These help to evaluate the corrosion resistance of materials.Comprehensive utilization of various electrochemical methods is beneficial to the analysis of corrosion mechanisms.Given the current research status and trend of corrosion in stainless steel,the electrochemical method is projected to be mainly implemented in the control of the corrosion processes.Therefore,there is need for better detection technologies to achieve a better analysis of the corrosion processes of stainless steels.