金属元素Co、Fe、Cu、Ti对孕镶金刚石基底CVD金刚石涂层膜基界面结合强度的影响

Effect of Metal Dopant on Interface Adhesion of Diamond Coating on Impregnated Diamond Substrate: A First Principle Calculation

采用基于密度泛函理论的第一性原理理论法,研究了金属元素Co、Fe、Cu、Ti对孕镶金刚石基底化学气相沉积金刚石涂层膜基界面结合强度的影响及其作用机理。界面结合能、电荷密度和化学键重叠布居数的计算结果表明:Co、Fe元素具有较强的电荷转移能力,Cu、Ti元素在沉积过程易生成金属碳化物过渡结构,且Cu、Ti元素掺杂模型膜基界面间C原子成键较强,成键也更接近理想金刚石C-C键,这些原因导致Cu、Ti元素掺杂模型的膜基界面结合强度较强,Co、Fe元素掺杂模型的膜基界面结合强度较弱。据此,可适当调整金属元素比例,优化工艺参数,从而改善孕镶金刚石钻头上沉积CVD金刚石涂层的性能。

The interface reactions of the metal-doped diamond coatings,deposited by chemical vapor deposition( CVD),and substrate of impregnated diamond bit( IDB) were mathematically modeled and theoretically analyzed in First Principle Calculation based on density functional theory. The influence of the metal dopants( Co,Fe,Cu and Ti) on the electronic structures,atomic structures and bonding energy at the interface was investigated. The calculated results show that the impact of dopants on interfacial adhesion can be listed in a descending order: Co > Fe > Cu and Ti. For example,Cu and Ti promote formation of carbide and diamond like C-C bond at the interface in diamond film growth,resulting in strong interfacial adhesion;Co and Fe dopants have a large charge transfer ability but an interface adhesion weaker than that of Cu and Ti. We suggest that the calculation be of some technological interest in surface modification of IDB.