高等级合金CO_(2)环境下的腐蚀行为研究

Corrosion Behavior of Heat-resistant Alloys in High Temperature CO_(2) Environment

以 Sanicro 25 奥氏体不锈钢和 HR230、740H 镍基合金为研究对象,在高温 CO_(2)环境下分别进行了 800、900 和 1000 ℃的腐蚀实验。利用分析天平获得材料反应前后的质量变化,利用 SEM/EDS 对合金反应后的形貌及腐蚀产物进行观察分析,利用XRD表征合金表面的腐蚀产物。结果表明:3种材料在高温CO_(2)环境下的腐蚀动力学曲线均符合抛物线规律,反应速率均随着温度的升高呈现量级的增加,表面腐蚀产物尺寸随着温度的升高不断增大。3种材料表面生成的腐蚀产物主要为富Cr氧化物。3种材料表面腐蚀产物结构存在差异,Sanicro 25 不锈钢上的呈多层,而 HR230 和 740H 合金上的为单层;HR230 和 740H 合金均存在内氧化现象,且740H 合金中高含量的 Al 和 Ti 使其内氧化程度更加严重,抗 CO_(2)腐蚀性能降低。因此,在高温CO_(2)环境下镍基合金HR230具有较为优越的抗腐蚀性能。

Corrosion behavior of Sanicro 25 austenitic steel, HR230 and 740H Ni-based alloys in CO_(2)environment at 800, 900 and 1000 ℃ was studied by means of weight gain measurement, scanning electron microscope with energy dispersive X-ray spectroscopy and X-ray diffractometer. The results showed that the corrosion kinetic curves of the three alloys in the high-temperature CO_(2)environment conformed to the parabolic law. The reaction rates of the three alloys all increased with the temperature, and the thickness of surface corrosion products also increased with the temperature. The corrosion products generated on the surface of the three alloys were mainly Cr-rich oxides, which were caused by the high content of Cr. However,the structure of the surface corrosion products of Sanicro 25 steel and HR230 and 740H alloys was different. Sanicro 25 steel was a composite layer type, HR230 and 740H alloys was a single-layer type;both HR230 and 740H alloys had internal oxidation, and the high content of Al and Ti in740H alloy made internal oxidation more serious, therewith degraded its corrosion resistance. According to the corrosion mass gain measurement results and the occurrence of internal oxidation phenomenon, the nickel-based alloy HR230 has superior corrosion resistance in high temperature CO_(2) environment.