锌在模拟工业大气环境下的腐蚀行为研究

摘要

目的：研究不同时间下锌在SO2环境中的腐蚀特性。方法采用室内加速试验法，向大气加速腐蚀箱中通入25 mg/L SO2气体，进行模拟工业大气环境下的加速腐蚀试验。对腐蚀后金属材料进行质量增量测量和电化学测试，通过XRD，SEM等表征锌腐蚀产物及腐蚀形貌，研究腐蚀特性。结果初期阶段锌在SO2环境中的腐蚀速率逐渐增加，到腐蚀后期逐渐降低，1/Rct值先增大后减小，锌的腐蚀产物中的元素包括Zn，O和少量的S，主要产物为Zn4SO4（OH）6。结论初期在锌表面生成的腐蚀产物疏松，SO2能够通过产物层到达基体，促进腐蚀，不具有保护性。到后期，产物增多并且致密使SO2与基体接触的概率降低，从而使腐蚀速率减缓。%ABSTRACT:Objective To study the characteristics of zinc corrosion on different time in SO2 environment. Methods Using the indoor accelerated test method, the accelerated corrosion experiment in simulated industrial atmospheric environment was carried out by filling 25 mg/L SO2 to the atmospheric accelerated corrosion box. Then mass weight measurement and electrochemical test were conducted for the corroded metal material. XRD and SEM were used to characterize the zinc corrosion products, observe the corrosion morphology and study the characteristics of corrosion. Results The corrosion rate of zinc in the SO2 environment increased in the early stages of corrosion, and decreased gradually in the late stage. The 1/Rct value first increased and then decreased. The elements in the corrosion products of zinc included Zn, O and a small amount of S, and the main product was Zn4SO4(OH)6. Conclusion In the early stage, the corrosion product formed on the zinc surface was loose, and SO2 could pass the product and arrive at the matrix to promote the corrosion, leaving the matrix unprotected. In the late stage, the increased and compact products decreased the probability for the contact of SO2 with the matrix, leading to reduced corrosion rates.