预氧化对高温CO_(2)环境下典型耐热材料腐蚀行为的影响研究

Effect of Pre-Oxidation on Corrosion Behavior of Typical Heat-Resistant Materials in High Temperature CO_(2)

为提高耐热材料在高温CO_(2)中的抗腐蚀性能,以耐热材料Sanicro 25、HR6W、HR230和740H为对象,经高温O_(2)短时预氧化后开展CO_(2)腐蚀实验。采用分析天平测量耐热材料腐蚀前后质量变化;利用X射线衍射仪、扫描电镜及能谱分析仪表征腐蚀产物形貌、成分及其分布。实验结果表明:预氧化后耐热材料在900℃CO_(2)中的腐蚀动力学曲线符合抛物线规律;预氧化后4种耐热材料表面氧化物主要为Cr的氧化物和少量零星团状的Fe氧化物,该富Cr氧化膜有效减低腐蚀行为的离子扩散,从而降低耐热材料的腐蚀质量增加;耐热材料Sanicro 25和HR6W表面腐蚀层厚度减薄,而740H内氧化加剧。结合耐热材料腐蚀质量变化与腐蚀产物,高温预氧化处理可提高HR6W和HR230的抗高温CO_(2)腐蚀性能。

To improve the corrosion resistance of heat-resistant materials in high-temperature CO_(2),such heat-resistant materials as Sanicro 25,HR6W,HR230 and 740H are pre-oxidized for a short period in high-temperature O_(2) and then tested for their corrosion resistance.An analytical balance is used to measure the mass of the heat-resistant materials before and after the test.X-ray diffractometer,scanning electron microscope and energy dispersive analyzer are used to characterize the morphology,composition and distribution of corrosion products.The test results show that the corrosion kinetics curves of the pre-oxidized heat-resistant materials in 900℃CO_(2) conform to the parabolic law;the surface oxides of the four heat-resistant materials after pre-oxidation are mainly Cr oxides and a small amount of sporadic Fe oxides,the Cr-rich oxide film effectively reduces the ion diffusion during the corrosion process,thereby reducing the corrosion weight gain of these materials.The corrosion layer on the surface of Sanicro 25 and HR6W is thinned,while the oxidation in 740H is intensified.It can be seen from their mass changes and corrosion products that high-temperature pre-oxidation can improve the corrosion resistance of HR6W and HR230 in high-temperature CO_(2).