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 be strong enough in order to have longer lifetime. Based on density functional theory the first-principles discrete variational (DV) method was used to study TBC. The energy and electronic structure of the Cr-doped interface of TBC (ZrO₂/Ni) 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.