次氯酸钠辅助的循环冷却水无磷钝化方案研究

Sodium hypochlorite assisted phosphorus-free passivation program of recirculating cooling water

研究了一种次氯酸钠辅助的循环冷却水无磷钝化方案。结果表明,适量的余氯能改善钝化过程。随着余氯从0增加至0.5 mg/L,碳钢表面逐渐形成均匀致密的蓝色保护膜,红点出现时间从5 s增加至30 s,电化学测量的碳钢在冷却水中的实时腐蚀率从0.1 mm/a降低至0.005 mm/a;而过量的余氯会导致腐蚀。对比传统的含磷钝化,其显著优势是药剂投加量低,成膜时间短,钝化后可直接切换至正常运行阶段,现场操作更方便。

A sodium hypochlorite assisted phosphorus-free passivation program of recirculating cooling water was studied.The result showed that the proper amount of residual chlorine could improve passivation process.With the increase on residual chlorine from 0 to 0.5 mg/L,the uniform and compact blue protective film gradually formed on the surface of carbon steel(CS).The occurrence time of red point increased from 5 seconds to 30 seconds.The corrosion rate of passivated carbon steel in cooling water measured by electrochemical method decreased from 0.1 mm/a to 0.005 mm/a.However,the excess residual chlorine could result in corrosion.Compare with traditional phosphorus-based passivation program,the significant advantage of this program is the lower dosage,shorter passivation time,direct switch to normal running phase after passivation,and more convenient on-site operation.