低合金耐热钢T23在高温超临界CO2环境中的腐蚀特性研究

2021-05-10 15:50:31 作者：李瑞涛来源：中国腐蚀与防护学报分享至：

摘要

通过低合金耐热钢T23在650 ℃/25 MPa的高温超临界二氧化碳（s-CO2）下的1000 h氧化实验获得了T23钢的氧化动力学特性，并借助SEM、XRD及EDS对氧化膜的形貌、物相和成分进行了分析。结果表明：T23钢在650 ℃/25 MPa的高温s-CO2中的氧化动力学符合立方规律，时间指数0.30。氧化膜具有典型的双层结构，外层氧化膜为Fe3O4且氧化膜疏松多孔，内层氧化膜较为致密含有大量尖晶石结构的Fe3-xCrxO4。T23材料在高温超临界CO2环境中形成的氧化膜较容易发生剥落，剥落腐蚀现象明显。

关键词： T23钢 ; 高温氧化 ; 高温s-CO2 ; 剥落腐蚀

Abstract

The long term oxidation behavior of T23 steel, one of the low alloy heat resistant steels was examined in high-temperature supercritical CO2 at 650 ℃/25 MPa for 1000 h, so that, the oxidation kinetics of T23 steel was acquired. Meanwhile, the oxide scales formed on the steel were characterized by SEM, XRD and EDS. The results showed that the oxidation kinetics of T23 steel oxidized in high-temperature s-CO2 at 650 ℃/25 MPa followed the cubic law during the entire test duration. Meanwhile, the time index was also obtained by data analysis process and proved to be 0.30. The oxide scales formed on all the samples exposed for different time duration had a typical double-layered structure. Namely，the outer layer was porous and composed of Fe3O4. The inner layer composed of Fe3-xCrxO4 and was much denser than the outer layer. Also, the oxide scale formed on T23 steel in high-temperature s-CO2 was more likely to peel off and the exfoliation-like corrosion could be found obviously on the surface of the corroded steel.

Keywords： T23 steel ; high-temperature oxidation ; high-temperature s-CO2 ; exfoliated corrosion