含卤体系不锈钢局部腐蚀发展研究的闭塞电池模型构建

Construction of Occluded Cell Model for the Study of Localized Corrosion Development in Stainless Steel in Halogen-Containing Systems

针对目前通过构建闭塞电池模型仅能对单一含卤体系不锈钢局部腐蚀展开研究的现状,构建氟氯离子共存体系中304不锈钢局部腐蚀发展的闭塞电池模型,通过单因素和正交实验分别确定模型的工作条件及主要影响参数,结合闭塞区pH值、离子迁移量、腐蚀电流和腐蚀速率对模型可用性进行验证。结果表明:构建的烟道气氨法脱硫浆液中304不锈钢局部腐蚀发展闭塞电池模型较好的工作环境为外加电压0.8 V、溶液温度50℃,模型本身的最佳影响参数组合为内溶液体积与阳极暴露面积比59、阴阳极暴露面积比10、模拟锈层厚度3 mm,该模型在含不同浓度氟氯离子的介质中均具有较好的可用性。

In view of the current situation that constructing an occluded cell model can only enable the study of localized corrosion of stainless steel in single halogen-containing system, a new occluded cell model for studying the development of localized corrosion of 304 stainless steel in a fluorine-chloride ion coexistence system was constructed, and the working conditions and main influencing parameters of such model were determined through single factor tests and orthogonal tests respectively. Meanwhile, the usability of the model was verified taking into account the pH value of the occluded zone, ion migration, corrosion current and corrosion rate. Results showed that for the constructed occluded cell model for the study of localized corrosion development of 304 stainless steel in the flue gas ammonia desulfurization slurry, an applied voltage of 0.8 V and a solution temperature of 50 ℃ were good working conditions. The optimal combination of influencing parameters was as follows: a ratio of internal solution volume to anode exposure area of 59, a ratio of cathode exposure area to anode exposure area of 10, and a simulated rust thickness of 3 mm. Moreover, the model presented good usability in media containing different concentrations of fluorine ions and chloride ions.