高温浓硫酸中氟离子掺入对不锈钢耐蚀性能的影响

Effects of fluoride ions on corrosion resistance of stainless steel in high-temperature concentrated sulfuric acid

采用浸泡法和电化学测试方法结合扫描电镜和能谱仪研究了高温浓硫酸中氟离子的掺入对304、2507以及904L三种不锈钢耐蚀性能的影响.结果表明:氟离子的掺入对三种不锈钢在浓硫酸中的腐蚀具有抑制作用,综合来看,904L具有更为稳定的耐蚀性能;三种不锈钢在高温浓硫酸中由于生成了热力学不稳定的硫化镍而产生了活化转钝化现象,而掺入氟离子会和硫离子发生竞争使其排挤出电极表面,氟离子与镍离子结合形成另外一种更稳定的阻挡层使不锈钢耐蚀性提高.

The effects of fluoride ions on the corrosion resistance of 304,2507,and 904L stainless steels in high-temperature concentrated sulfuric acid were investigated by immersion and electrochemical tests as well as scanning electron microscopy（SEM）and energy-dispersive X-ray spectroscopy（EDS） analyses.The results show that the corrosion resistances of these three stainless steels improve when fluoride ions are added in high-temperature concentrated sulfuric acid.Of the three,the corrosion resistance of 904L is more stable and reliable.The nickel sulfide formed in sulfuric acid,which is thermodynamically unstable,causes active-passive transition.The corrosion resistance of stainless steel increases upon the addition of fluorine ions because the nickel and fluorine ions form a more stable compound to replace nickel sulfide.