摘要
基于量子力学第一性原理,建立了IDB-B/Diamond、IDB-Al/Diamond、IDB-Sn/Diamond和IDB-Co/Diamond 4种膜基界面模型,计算了膜基界面结合能、差分电荷密度和布居数,以探究孕镶金刚石钻头(impregnated diamond bits,IDB)基体中的常用元素X(X=B、Al、Sn、Co)对IDB-X/Diamond膜基结合强度的影响机制。计算结果表明:膜基界面结合能大小为W_(ad-B)>W_(ad-Al)>W_(ad-Co)>W_(ad-Sn);B、Al是增强膜基结合强度的有益元素,因为B、Al原子的电荷主要转移到掺杂位点附近的C1~C3原子,其与C1~C3原子的键合作用强;Sn、Co会削弱膜基结合强度,这是由于Sn、Co原子与C1~C3原子的键合作用弱,同时膜基界面间的其他C原子因俘获电荷而相斥。压痕对比的实验结果与仿真结论相符。
Objectives:At present,resource exploration and mining continue to expand to deep underground.Impregnated diamond bits(IDB)with excellent performance have become the main tool for deep underground drilling.Our research group has found that depositing a layer of CVD diamond coating in situ on the surface of IDB can achieve homogeneous epitaxial growth and heterogeneous epitaxial growth of diamond coatings,which can improve the working life of IDB.This article is based on the first principles of quantum mechanics and uses the CASTEP computational tool to study the influence mechanism of X(X=B,Al,Sn,Co)elements commonly used in the IDB on the interfacial bonding performance of CVD diamond coatings on IDB from a microscopic perspective.It provides a theoretical reference and basis for further optimizing the formulation of drill bit substrates and improving the interfacial bonding strength between the film and substrate.Methods:This article uses the CASTEP module of the quantum mechanics computing software Materials Studio to study the influence mechanism of X(X=B,Al,Sn,Co)elements commonly used in IDB on the interfacial bonding performance of CVD diamond coatings on IDB from a microscopic perspective.Firstly,establish[100]crystal orientation,3×3 size IDB,and CVD diamond coating supercell models,with dimensions of 7.54Å×7.54Å×3.56Åalong the X,Y,and Z directions.After adding a vacuum layer with a thickness of 12Å,the IDB model and CVD diamond coating model are obtained.Then,replace the C atoms at specific locations on the surface of the IDB model with X(X=B,Al,Sn,Co)atoms.Afterwards,the IDB-X substrate is combined with the CVD diamond coating model along the[100]crystal plane to establish an IDB-X/Diamond film substrate interface model.After testing,the film-substrate interface spacing is set to 2Å.Next,the CASTEP module is used to optimize the IDB-X/Diamond filmsubstrate interface model doped with X(X=B,Al,Sn,Co)atoms.The properties of the four film-substrate interface models are analyzed from the aspects of film-substrate interface binding energy,differential charge density,and Mulliken population.Finally,verification is conducted with indentation experiments.Results:(1)From the perspective of film-substrate interface binding energy,the binding energies of B,Al,Co,and Sn atom doping are 11.68,9.94,7.38,and 6.85 J/m^(2),respectively.Based on the weakening phase Co of the film-substrate interface binding energy,the film-substrate interface binding energy doped with B and Al atoms is significantly higher than that of Co atoms,indicating that the B and Al elements in the substrate are beneficial for improving the film-substrate interface binding energy.The filmsubstrate interface binding energy doped with Sn atoms is similar to that of Co atoms,indicating that the Sn element in the substrate also weakens the bonding strength between the film and substrate.(2)From the perspective of differential charge density,the charges of B,Al,Sn,and Co atoms all tend to transfer to the surrounding C atoms,especially to the C1−C3 atoms in CVD diamond coatings,and the tendency to transfer charges to C1 atoms is more pronounced.This indicates that the four doped atoms have a stronger effect on the charges generated by the C atoms in the film.The density of charge transfer from B atom to C1−C3 atom is relatively high,which reflects the strong charge interaction between B atom and C1−C3 atom.The tendency of Al atoms to transfer charges is mainly concentrated in C1 and C2 atoms,and the tendency to transfer charges to C3 atoms is not obvious,indicating that the bonding between Al atoms and C1 and C2 atoms may be stronger.The tendency of Sn atoms to transfer charges to C1 atoms is obvious,but the tendency to transfer charges to C2 and C3 atoms is slightly weaker,indicating that the charge interaction force between Sn atoms and C atoms in the substrate is weak.Co atoms have a weak tendency to transfer charges to C1 and C3 atoms,while their tendency to transfer charges to C2 atoms is not significant,indicating that the charge interaction between Co atoms and the film and substrate is weak.(3)From the perspective of atomic and chemical bond Mulliken population,B,Al,Sn,and Co all lose electrons and carry positive charges,with charge loss numbers of 0.59e,1.89e,2.06e,and 1.71e,respectively.Meanwhile,the C1−C3 atoms near the four doping elements all receive negative charges,indicating significant charge transfer between the four doped atoms and C1−C3 atoms.This suggests the existence of four types of bonding interactions between the film-substrate interface interface:C−B,C−Al,C−Sn,and C−Co.The effective utilization rates of the lost charges of B,Al,Sn,and Co atoms by C1~C3 atoms are 98%,58%,43%,and 39%,respectively.The Mulliken population of the C−B bond is the largest and the bond length is the smallest,followed by the Mulliken population of the C−Al bond.The Mulliken populations of the C−Sn bond and C−Co bond are relatively small.(4)From the indentation experiment,it can be seen that the indentation of diamond films pretreated with B and Al elements is shallow and the pit area is small,indicating that the film-substrate interface binding strength of IDB-B/Diamond and IDB-Al/Diamond is high.Among them,the indentation pit area of diamond films pretreated with B element is the smallest,indicating that B element is most conducive to enhancing the film-substrate interface binding strength,followed by Al element.The diamond coatings pretreated with Sn and Co elements have deeper indentation and a larger indentation pit area,indicating poor film-substrate interface effect of IDB-Sn/Diamond and IDB-Co/Diamond.Conclusions:(1)From the perspective of energy,the binding energy of the film-substrate interface doped with four elements is W_(ad-B)(11.68 J/m^(2))>W_(ad-Al)(9.94 J/m^(2))>W_(ad-Co)(7.38 J/m^(2))>W_(ad-Sn)(6.85 J/m^(2)).Based on the weakening phase of the film-substrate interface binding energy of the Co element,the doping of B and Al elements are conducive to improving the filmsubstrate interface bonding strength.The film-substrate interface binding energy of Sn element doped is similar to that of Co element,indicating that Sn element doped also weakens the film-substrate interface bonding strength.(2)From the perspective of charge,the charges of B and Al atoms mainly transfer to the C1−C3 atoms near the doping site,with effective charge utilization rates of 98%and 58%,respectively.In addition,the Mulliken populations of C−B and C−Al bonds are relatively high,indicating that the bonding between B and Al atoms and C1−C3 atoms is strong,playing the role of film substrate connection nodes and improving the film substrate interface binding strength.The effective charge utilization rates of Sn and Co atoms are both less than 50%,indicating that a large amount of charge is transferred to other C atoms at the film substrate interface except for C1−C3 atoms,resulting in weak bonding between Sn and Co atoms and C1−C3 atoms.At the same time,other C atoms repel each other due to the charge obtained,weakening the film substrate interface binding strength.(3)From the indentation experiment,it can be seen that the film-substrate interface bonding strength of B element-induced crystal pretreatment is the highest,followed by Al element,while Sn and Co elements are relatively poor.
作者
简小刚
姚文山
张毅
梁晓伟
胡吉博
陈哲
陈茂林
JIAN Xiaogang;YAO Wenshan;ZHANG Yi;LIANG Xiaowei;HU Jibo;CHEN Zhe;CHEN Maolin(School of Mechanical Engineering,Tongji University,Shanghai 201804,China)
出处
《金刚石与磨料磨具工程》
北大核心
2025年第1期37-45,共9页
Diamond & Abrasives Engineering
基金
国家自然科学基金(51275358)
中央高校专项基金(20140750)。
关键词
第一性原理
金刚石涂层
膜基结合
电荷转移
布居数
压痕实验
first-principles
diamond coating
membrane-based binding
charge transfer
Mulliken population
indentation experiments
