镀锌板在不同加速腐蚀环境下的腐蚀行为研究

目的研究中性盐雾环境、中性盐雾加周浸环境和中性盐雾加湿热环境下镀锌板的腐蚀行为,明确不同加速腐蚀试验环境对镀锌板腐蚀行为的影响。方法对镀锌板进行中性盐雾、中性盐雾加周浸、中性盐雾加湿热等不同类型的加速腐蚀试验,通过失重法、SEM、XRD以及极化曲线等方法,对比不同加速腐蚀试验类型对镀锌板腐蚀行为的影响。结果在三种加速腐蚀试验环境下,镀锌板的腐蚀过程基本相同:镀锌层及白色锌锈腐蚀、锌层破裂、锌层完全脱落、基体碳钢腐蚀。腐蚀产物都以Zn(OH)_2、γ-FeOOH、ZnO、Fe_2O_3等为主。三种环境下镀锌板的腐蚀都不均匀,不同位置的腐蚀情况存在一定差异。其中,中性盐雾环境下材料腐蚀情况最为严重,中性盐雾加周浸环境次之,中性盐雾加湿热环境下最轻。结论三种加速环境都是主要通过Cl~-在锌表面的沉降和溶解作用增强介质的导电性能,加剧锌层的腐蚀。在中性盐雾环境中,Cl~-浓度最高,试样腐蚀最严重。在中性盐雾加周浸环境中,SO_4~(2-)与Cl~-协同作用,腐蚀也较严重。而中性盐雾加湿热环境中,Cl~-被稀释,腐蚀情况最轻微。

Corrosion Behaviorof Galvanized Sheet in Different Accelerated Corrosion Environment

The work aims to study corrosion behavior of galvanized sheet in neutral salt spray,neutral salt spray & periodic immersion as well as neutralsalt spray &heat and humidity environments,so as to clarify effects of different accelerated corrosion test environment on corrosion behavior of galvanized sheet.Different kinds of accelerated corrosion test including neutral salt spray,neutral salt spray & periodic immersion as well as neutralsalt spray &heat and humidity environments were performed to galvanized sheet.Effects of different accelerated corrosion test types on corrosion behavior of galvanized sheet were compared in weight loss method and using SEM,XRD and polarization curve.Corrosion process of galvanized sheet was basically the same in three accelerated corrosion environment:zinc coating and white zinc were rusted and corroded,zinc coating fractured and fell off completely,and substrate carbon steel was corroded.Corrosion products were mainly Zn(OH)2,γ-FeOOH,ZnO,Fe2O3.Galvanized sheet was corroded unevenly in three environment,and corrosion conditions varied in different positions.Corrosion of galvanized sheet was most serious in neutral salt spray environment,more serious in neutral salt spray & periodic immersion environment,and the least in neutralsalt spray & heat and humidity environment.Three accelerated environments enhances conductivity of the medium based upon deposition and dissolution of CV on zinc surface,and accelerates corrosion of zin coating.Cl-concentration is the highest,and sample corrosion is the worst in neutral salt spray environment.SO42-and Cl-have synergistic effect and corrosion is relatively severe in salt spray and periodic immersion environment.The Cl-is diluted and corrosion is slight in neutralsalt spray &heat and humidity environment.