Cr对ZrO2/Ni热障涂层界面结合的影响

热障涂层广泛用于航空、航天领域,涂层与基体的界面结合强弱是决定涂层寿命的一个关键因素.为了提高其使用寿命,必须要求涂层与基体的界面有较好的结合.利用密度泛函理论框架下的第一性原理离散变分(DV)方法研究了ZrO₂Ni热障涂层界面的能量学和电子结构,讨论了替位型掺杂的Cr在ZrO₂Ni热障涂层界面中的作用.结果表明:Cr容易偏聚于界面处(偏聚能达6.03eV),Cr使得体系结合能增加,体系更稳定,有利于界面的结合;界面处原子电荷占据数和电荷密度计算表明:加入Cr后跨界面方向的电荷密度增加,同时也使得界面内电荷密度增加,这有利于跨界面方向的以及沿界面方向的成键,从而加强了涂层与基体材料的结合.

Effect of Cr on ZrO2/Ni thermal barrier coatings interface cohesion

The thermal barrier coatings (TBC) are widely used in aeronautics and astronautics industry. The cohesion between the coatings and substrate is a vital effect in determining the TBC lifetime. The interface cohesion must strong enough in order to have longer lifetime. Based on density functional theory the first-principles discrete variational (DV) method was used to study the thermal barrier coating. The energy and electronic structure of the Cr-doped interface of TBCs (ZrO₂Ni) were investigated. Result shows that after adding Cr on the interface, the system’s energy is reduced. The segregation energy of Cr is 6.03 eV. This means the system is more stable when Cr atom segregates on interface than that of clean system. Further analysis shows that the interface’s charge-density is increased after adding Cr, this is propitious to bond on the direction of spanning the interface, thereby the bonds between the substrate Ni and ZrO₂ are enhanced; the bonds between atoms neighboring to Cr atom in plane are also enhanced.