摘要
针对超临界CO_(2)动力循环高温承压部件与工质相容性问题,研究了T92耐热钢在600和700℃超临界CO_(2)环境下的腐蚀过程动力学及其热力学产物。采用分子动力学计算了CO_(2)在FeCr合金表面的吸附过程,模拟了T92耐热钢在初始氧化阶段原子的迁移和分布规律,并基于腐蚀热力学原理,分析了氧化层和碳化物的分布规律,最后通过高温腐蚀实验进行了验证。研究结果表明:700℃时,T92耐热钢氧化层厚度约为600℃时的13.5倍,氧化层结构为外侧Fe_(3)O_(4)层、内侧FeCr_(2)O_(4)层,氧化层内部主要为C 23 C 6型碳化物;CO_(2)优先吸附于Cr原子(111)表面,当Cr与CO_(2)发生反应后,部分形成游离态的C沉积于氧化层表面,并以离子的形式向内扩散;腐蚀过程主要由离子扩散控制,扩散速率随着温度的升高而增大。该研究为超临界CO_(2)材料抗腐蚀性能评估提供了一种复合分析方法,也为关键高温承压部件材料的遴选及腐蚀寿命预测提供了数据支撑。
For the challenges arising from the compatibility between the high-temperature pressure-bearing parts in the supercritical CO_(2)power cycle system and the working medium,the corrosion kinetics and the corresponding thermodynamic products of T92 steel in supercritical CO_(2)environments at 600 and 700℃were studied.Firstly,the adsorption process of CO_(2)on the surface of T92 steel was calculated by molecular dynamics and the migration and distribution of atoms in T92 steel during the initial oxidation stage were simulated.Then,the distribution of oxide layers and carbides was analyzed based on the principle of corrosion thermodynamics.Finally,the high-temperature corrosion tests were carried out to verify the simulation results.The results showed that the thickness of the oxide layer on T92 steel at 700℃was about 13.5 times higher than that at 600℃.The oxide layer consisted of an outer layer of Fe 3O 4 and an inner layer of FeCr_(2)O(4).Under the oxide layer,there are C 23 C 6 carbides.CO_(2)was preferentially adsorbed on the surface of Cr(111).Then Cr reacted with CO_(2)to form some free C deposited on the surface of the oxide layer,which diffused inwards in the state of ions.The corrosion process was dominated by ion diffusion,and the diffusion rate increased with the temperature.The study provides a composite analysis method to evaluate the corrosion resistance of materials in the supercritical CO_(2)and data support for materials selection and corrosion lifetime prediction of key high-temperature pressure-bearing parts.
作者
郭亭山
梁志远
赵钦新
GUO Tingshan;LIANG Zhiyuan;ZHAO Qinxin(Key Laboratory of Thermo-Fluid Science and Engineering of MOE,Xi’an Jiaotong University,Xi’an 710049,China)
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2023年第12期136-145,共10页
Journal of Xi'an Jiaotong University
基金
国家自然科学基金资助项目(52276015)
中国博士后基金资助项目(2020M683474)。
关键词
超临界CO_(2)
分子动力学
腐蚀热力学
高温腐蚀
supercritical CO_(2)
molecular dynamics
corrosion thermodynamics
high-temperature corrosion
