含镀层合金钢循环盐雾加速腐蚀行为与机理研究

目的 研究含镀层合金钢在室内模拟及强化腐蚀环境下的腐蚀行为与机理,建立快速评价含镀层钢腐蚀寿命的加速试验方法.方法 利用设计的室内加速腐蚀环境试验谱,通过实施模拟海洋大气环境效应的循环盐雾加速腐蚀试验,采用外观检查、SEM、XRD及电化学测试等手段,表征了暴露不同周期样品的腐蚀失重、腐蚀形貌、腐蚀产物成分、极化曲线及阻...

Accelerated Corrosion Behavior and Mechanism of Coated Alloy Ateel by Cyclic Salt-spray Test

This paper aims to study the corrosion behavior and mechanism of coated alloy steel under the laboratory simulation and strengthened corrosion environment, and establish the accelerated test methods for evaluating the corrosion life of coated steel.Utilizing the designed test spectrum of accelerated corrosion environment in laboratory simulation, cyclic salt-spray accelerated corrosion tests were performed to simulate the marine atmospheric environment effect. By such instruments as appearance inspection, SEM, XRD, electrochemical measurement etc., the corrosion performance of specimens with different exposure time, such as corrosion weight loss, corrosion morphology, corrosion product composition, polarization curves and impedance spectroscopy were characterized. Accelerated corrosion behavior and mechanism of coated alloy steel were analyzed and concluded. As the corrosion exposure time progresses, corrosion weight loss of the coated alloy steel specimen conformed to the power function law, the corrosion rate decreased, increased and decreased. The surface morphology transited gradually from corrosion products of the coating layer to the rust layer of substrate metal, and the main chemical constituents of corrosion products from hydroxy-zinc-chloride and zinc-hydroxide to iron-hydroxide gradually. The corrosion current density fitted by polarization curves fluctuated around the average value, and the corrosion potential fluctuated upwards. Capacitive loops of electrochemical impedance spectroscopy varied from one to two, and the low and medium frequency of capacitive loops appeared a straight line representing typical characteristics of Warburg impedance. Therefore conclusions are obtained as follows,the accelerated effect is significant for the coated alloy steel corrosion by cyclic salt-spray test, the corrosion behavior and mechanism of coated alloy steel are more comprehensively characterized from such aspects as corrosion kinetics, morphology and constitutes of corrosion products, and electrochemical mechanism to provide conditions for further investigating the simulation and correlation of accelerated corrosion test.