两种高铬铸铁在热强碱中的腐蚀行为

Corrosion behavior of two types of cast iron containing Cr in hot concentrated NaOH solutions

高铬铸铁是工业上应用较为广泛的材料之一,但此类材料在热强碱冲刷腐蚀条件下寿命较短.以工业上常用的两种高铬铸铁Cr13和Cr26为试验材料,研究其在热强碱介质中静态浸泡的腐蚀行为,并通过电位-时间曲线、极化曲线实验和电子显微进行了分析.研究结果表明:高铬铸铁在试验介质中的腐蚀分3个阶段,氧化膜的溶解、基体溶解、腐蚀产物保护下的溶解;3个阶段历时不同,第2阶段具有最大的溶解速度;腐蚀形式是均匀腐蚀兼有腐蚀开裂和相界腐蚀;腐蚀开裂在第2阶段就可被观察到并且有可能是第3阶段腐蚀的主要形式;在热强碱介质中静态浸泡时,Cr13的耐腐蚀性能优于Cr26.

High chromium cast iron is widely used in industry, but the service life of this kind of material is short when suffering from wearcorrosion in hot concentrated alkaline solution, and there are few researches on the subject. This work focuses is on the corrosion behavior of Cr13 and Cr26 irons when they are immersed in the hot concentrated alkaline solution. Curves of potential versus time, polarization curves and micrographs are analyzed. It is concluded that the corrosion includes three stages: oxidize film dissolution, basic body dissolution and dissolution under the corrosion product. The dissolution of three stages last different period of time, and the highest dissolution rate is in the second stage. The corrosion form is general corrosion with corrosion cracking and corrosion at interface, and the corrosion cracking can be observed in the second stage and may be the chief kind of corrosion in the third stage. The experiments demonstrated that Cr13 iron resists corrosion better than Cr26 when they are immersed in the hot concentrated alkaline solution.