不锈钢在湿法磷酸中腐蚀行为研究

Corrosion behaviour study of stainless steels in wet phosphoric acld

本文采用腐蚀实验和电化学测试方法对不锈铜在湿法磷酸中的腐蚀行为进行了研究，并进行钝化膜的组成与结构分析。研究表明，磷酸中加入Ｓ、Ｃｌ￣－、Ｆ￣－均提高合金的维钝电流密度和致钝电流密度，加速材料的腐蚀，这些杂质共存时腐蚀性更大。湿法磷酸中存在的Ｓｉ￣（４＋）、Ａｌ￣（３＋）、Ｍｇ￣（２＋）和Ｆｅ￣（３＋）起缓蚀作用。不锈钢钝化膜主要由Ｃｒ和Ｆｅ的氧化物组成，表面形成致密稳定的Ｃｒ＿２Ｏ＿３保护膜是提高不锈铜耐蚀性的关键。

study was conducted for corrosion behaviour ofstainless steels in wet phosphoric acid by using corrosionexperiments and electrochemical tests,and the compositionand structure of passive film were analysed. The researchshowed that the passivation current density and passivecurrent density of alloys were increased by adding Cl￣-,F￣-to phosphoric acid, and the corrosion of materialswould be accelerated, corrosion would be more seriouswhen,Cl￣-,F￣- were put together at the same time.Si￣(4+),Al￣(3+),Mg￣(2+),and Fe￣(3+) acted as inhibitors in wet phos-phoric acid.The passive film of stainless steels compositedmainly of oxidates of chromium and iron,stable and com-pact Cr_2O_3 protection film formed on surface of stainlesssteel was the key factor for raising corrosion resistance of stamless steels.