镍在超临界H_(2)O/CO_(2)混合工质中腐蚀的反应力场分子动力学模拟

Reactive force field molecular dynamics study of nickel corrosion in supercritical H_(2)O/CO_(2)mixtures

超临界H_(2)O/CO_(2)混合物是煤炭超临界水气化新型热力循环的工质,研究结构材料在其中的腐蚀行为可为热力发电系统的安全、高效运行提供指导。该文采用反应力场分子动力学模拟方法研究了模型材料镍在超临界H_(2)O/CO_(2)混合工质(25 MPa、873 K)中的腐蚀过程。模拟结果既追踪了H_(2)O和CO_(2)分子在Ni表面的吸附、解离等微观过程,又观察到H_(2)、CO等宏观实验观测到的中间产物。该文跨尺度地揭示了Ni在超临界H_(2)O/CO_(2)混合工质中腐蚀并最终形成稳定的复杂氧化层的反应机理。

Supercritical H_(2)O/CO_(2)mixture is the working fluid of a novel power generation system with coal gasified in supercritical water.Understanding of the structural material corrosion behavior is important for safe and high-efficiency operations of the system.In this work,nickel corrosion in the supercritical H_(2)O/CO_(2)mixture is investigated using the reactive force field molecular dynamics simulations for 25 MPa and 873 K.The adsorption and dissociation processes of H_(2)O and CO_(2)are interpreted,and H_(2),CO and other intermediate products are also observed in simulation results.Therefore,this multi-scale work demonstrates the mechanism of the complex process of nickel oxidation and corrosion in the supercritical H_(2)O/CO_(2)mixture.