循环水微碱化的换热器腐蚀控制  

Corrosion Inhibiting of Heat-Exchanger during Circulating Cooling Water Micro-Alkalization Process

作　　者：曾惠明[1] 金洁[2] 范蕊[1] 徐天有[1] 吕亮[1] 

机构地区：[1]衢州学院化学与材料工程学院,浙江衢州324000 [2]武汉大学动力与机械工程学院,湖北武汉430072

出　　处：《材料保护》2015年第10期41-44,8,共4页Materials Protection

基　　金：国家自然科学基金面上项目(21271116;21476127)资助

摘　　要：为实现循环冷却水微碱化调质的平稳控制，抑制换热器金属件表面的腐蚀，考察了H68黄铜在以H2O2为钝化剂的Na2CO3-NaHCO3缓冲溶液中的腐蚀行为。通过正交试验优选了H2O2浓度、温度及碱度等成膜条件；通过电化学试验研究了循环冷却水微碱化阶段换热器钝化膜形成及发展过程。结果表明：H2O2浓度为0．6％，溶液碱度为18mmol／L，温度20—30℃条件下钝化后，H68黄铜表面产生了薄而致密的Cu2O膜，在碱度为3．0mmol／L的碳酸盐溶液中挂片12d后，其腐蚀速率仅为0．0006mm／a；在碱度为2．0-3．0mmol／L的微碱化循环冷却水中，氧化膜的阻抗和厚度先逐渐降低，48h之后最低，之后上升，至144h后达到稳定，并恢复至初始水平，氧化膜转化为颗粒较粗CuO膜；本工艺实现了循环冷却水微碱化过程中钝化膜形成与发展的平稳过渡，换热器H68黄铜件表面形成了致密的氧化膜，既防止了局部腐蚀又抑制了均匀腐蚀。Corrosion behavior of H68 brass standard test pieces in the buffered solution(Na_2CO_3-NaHCO_3) with H_2O_2 as passivator was investigated.The operating parameters like the concentration of H_2O_2,the temperature and alkalinity were optimized through orthogonal experiments,and the passive film forming and developing procedures were studied by electrochemical tests.Results showed that the optimized operating parameters to form the thin and dense Cu_2O film were as follows:volume fraction of H_2O_2 of0.6%,the alkalinity of 18 mmol/L and temperature of 20-30℃.Under the optimized conditions,the corrosion rate of the test pieces was 0.000 6 mm/a after the hanging-sheet test for 12 d in the solution with an alkalinity of 3.0 mmol/L.In the simulated micro-alkalization circulating cooling system(alkalinity of 2.0-3.0 mmol/L),the impedance and thickness of the oxide film were firstly decreased and reached the lowest at 48 h and then increased gradually to a stable value at 144 h,which was equal to the initial level.The process fulfilled the smooth transition from the forming to the developing of the passivation film in the circulating cooling water micro-alkalization process,and the dense oxide film was formed and developed on the heat exchanger brass parts H68,which inhibited both the localized corrosion and the uniform corrosion.

关 键 词：H20:钝化 微碱化 换热器H68黄铜件 钝化膜发展规律 循环冷却水 

分 类 号：TG146.11[一般工业技术—材料科学与工程] TQ051.5[金属学及工艺—金属材料]