暗棕壤中Cl-/SO42-质量比对镀锌钢和不锈钢腐蚀行为的影响

Effect of Cl^(-)/SO_(4)^(2-) mass ratio on corrosion behavior of zinc-coated steel and stainless steel in dark brown forest soil

[目的]探究吉林地区暗棕壤中氯离子(Cl^(-))和硫酸根离子(SO_(4)^(2-))对典型接地材料腐蚀的影响。[方法]通过室内加速腐蚀试验考察不同Cl^(-)/SO_(4)^(2-)质量比下镀锌钢和不锈钢腐蚀速率的变化,采用X射线衍射仪和扫描电子显微镜分析金属腐蚀产物的变化,探讨镀锌钢和304不锈钢的腐蚀机理。[结果]低浓度SO_(4)^(2-)的存在会促进Cl^(-)对镀锌钢的点蚀,SO_(4)^(2-)浓度高则能减缓Cl^(-)对镀锌钢的腐蚀。但镀锌层厚度有限,在强酸性环境下会因为快速溶解而逐渐失去防腐作用。与镀锌钢相比,304不锈钢在暗棕壤中的耐蚀性更优,但其成本更高,并且304不锈钢的点蚀随着Cl^(-)/SO_(4)^(2-)质量比的增大而加剧。[结论]镀锌钢较适用于温和的中性土壤环境。304不锈钢比镀锌钢更耐腐蚀,但不适用于腐蚀性阴离子含量高的土壤环境。

[Introduction]The effects of chloride ions(Cl^(-))and sulfate ions(SO_(4)^(2-))on the corrosion of typical grounding materials in dark brown forest soil in Jilin need to be studied.[Method]The corrosion rates of zinc-coated steel and 304 stainless steel at different Cl^(-)/SO_(4)^(2-)mass ratios were examined by indoor accelerated corrosion test.The changes of corrosion products of zinc-coated steel and 304 stainless steel were analyzed by X-ray diffraction(XRD)and scanning electron microscopy(SEM).The corrosion mechanisms of zinc-coated steel and 304 stainless steel were discussed.[Result]The presence of low concentration of SO_(4)^(2-)promoted the pitting corrosion of zinc-coated steel caused by Cl^(-),while high concentration of SO_(4)^(2-)slowed down the pitting corrosion of zinc-coated steel.However,the zinc coating whose thickness was limited would gradually lose its anticorrosive effect due to rapid dissolution in strongly acidic environment.Compared to zinc-coated steel,304 stainless steel had better corrosion resistance in dark brown forest soil,but its cost was higher.In addition,the pitting corrosion of 304 stainless steel became worse with the increasing of Cl^(-)/SO_(4)^(2-)mass ratio.[Conclusion]Zinc-coated steel is applicable to mild neutral soil condition.304 stainless steel is not suitable for soil environments with high concentration of corrosive anions though it has better corrosion resistance than zinc-coated steel.