超临界二氧化碳中材料的腐蚀行为

Corrosion Behavior of Materials in Supercritical CO 2 Cycle

以超临界二氧化碳(SCO2)为工质的布雷顿循环相比于传统的水蒸气朗肯循环,具有更好的转换效率和经济优势。为了研究材料在SCO2系统中的耐腐蚀性能,自主设计搭建了SCO2循环腐蚀试验系统,对目前动力设备中常用的Cr-Mo-V合金钢、9%~12%Cr铁素体钢、奥氏体不锈钢和镍基高温合金等17种材料在600℃和700℃高温高压SCO2介质中的耐腐蚀性能进行了测试和分析。腐蚀称重、扫描电镜和能谱分析的结果表明:材料的抗二氧化碳腐蚀能力与合金Cr含量呈正相关性,Cr-Mo-V合金钢和9%~12%Cr铁素体钢的腐蚀增重随时间呈现抛物线规律,在钢的表面和内部裂纹处均发生了渗碳;奥氏体不锈钢在短期内能保持一定的抗腐蚀能力,但长时后腐蚀增重严重;镍基高温合金在700℃、20 MPa下3 000 h后仍表现出良好的耐腐蚀性能。

Compared with the traditional steam Rankine cycle,the Brayton cycle with supercritical carbon dioxide(SCO 2)as working medium has better conversion efficiency and economic advantages.In order to study the corrosion resistance of materials in SCO 2 system,a test system of corrosion in SCO 2 cycle was built.By means of weighing oxide,SEM and EDS,corrosion of 17 materials including Cr-Mo-V alloy steel,9%~12%Cr ferrite steel,austenitic stainless steel and nickel-based alloy was analyzed under SCO 2 of high temperature(600℃and 700℃)and high pressure.The results showed that there was a positive correlation between the content of chromium and the anti-carbon dioxide oxidation,and the weight gain of Cr-Mo-V alloy steel and 9%~12%Cr ferrite steel followed parabolic law.The phenomenon of carburizing was observed on the surface of steel and in the cracks.Austenitic stainless steel could maintain definite corrosion resistance in short time,however,its weight gain of oxidation was severe after a long time.The nickel-based alloy showed excellent corrosion resistance at 700℃and 20 MPa after 3000 h.