水冷壁镍涂层Na盐结渣的密度泛函理论研究

Study on Density Functional Theory of Water Wall Nickel Coating for Sodium Salt of Slagging

通过第一性原理(First principles)的密度泛函理论,利用Material studio的CASTEP模块,计算了不同覆盖度下Na盐在NiO涂层表面不同吸附位的吸附结构、吸附能、差分电荷密度及局域态密度,从原子层面研究通过铁基材料表面Ni涂层减轻结渣的机理。由表面吸附的分析可知,Na在涂层NiO(111)面的吸附稳定位为洞位;由差分电荷密度分析可知,涂层水冷壁表面发生的煤灰粘结过程主要是物理吸附过程;由洞位局域态密度分析可知,计算模型越接近实际模型,Na3s轨道和Ni3d轨道反键态电子越多,成键态电子越少,平均成键电子数越少,Na与Ni之间的相互作用越弱,导致吸附能数值减小,从而说明通过Ni涂层技术可以大大减轻Na盐结渣。

Using CASTEP module of material studio,adsorption structure,adsorption energy,differential charge density and the density of localized state of sodium salt in NiO coating surface at different adsorption sites were calculated at different coverage by first principles based on the density functional theory,the mechanism of reduce the slagging were studied using Ni coating on the iron-base material surface in the atomic level The stable adsorption site that Na in NiO（111） coating surface is the hole site according to the analysis of the surface adsorption; the bonding process in water wall coating surface of coal ash is mainly physical adsorption process according to the differential charge density analysis; when the calculation model more closer to the actual model,the more anti-bonding electrons of Na3s and Ni3d orbital electrons,the less bonding electrons and the number of average bonding electrons,weakens the interaction of Na and Ni,which results in lower numerical of adsorption energy,because of the density analysis of hole site localized state,using the coating technology of Ni can significantly reduce the slagging of sodium salt.