Influence of line defect in cemented carbide substrate on bonding strength between diamond coating film and substrate
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摘要: 基于密度泛函理论的第一性原理平面波赝势方法,研究了不同硬质合金基底线缺陷率下的金刚石涂层膜基界面结合强度。通过建立[111]、[110]、[100]3种不同晶向的金刚石涂层膜基界面分子模型,研究了硬质合金基底线缺陷率对涂层膜基界面结合强度的影响以及[111]、[110]、[100]3种不同金刚石涂层晶向下的最优膜基界面结合强度。研究结果表明:硬质合金基底的表面能随着基底线缺陷率的增加而逐步增大;当线缺陷率ρ=12.5%时,基底表面能达到最大值;其后,随着基底线缺陷率继续增大,基底表面能逐渐呈减小趋势。进一步研究显示,不同晶向的金刚石涂层膜基界面的最优界面结合能的最优线缺陷率不同,[111]晶向和[110]晶向的金刚石涂层的最优基底线缺陷率均为6.25%,而[100]晶向金刚石涂层的最优基底线缺陷率则为0%。Abstract: The first principles plane wave pseudopotential method based upon density functional theory (DFT) is used to investigate the bonding strength of diamond coating film on cemented carbide substrate with different line defect ratios.The interface molecular models between diamond coating film and substrate are built with different crystal orientations namely[111],[110]and[100], which are used to study the influence of the line defect ratio in cemented carbide substrate on the bonding strength of boundary and best interfacial bonding strength with three different crystal orientations.Resultsshow that the surface energy of cemented carbide substrate increases at first and then decreases as the line defect ratio in substrate surface grows and that when the line defect ratio ρ is 12.5%, the surface energy reaches to the maximum.It is further found that the optimal bonding energy of diamond coating interface with different crystal orientations have different optimal line defect ratios of substrate.The optimal line defect ratio ρ is 6.25%for diamond crystal of[111]and[110]orientations, but ρ=0for[100]orientation.
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Key words:
- diamond coating /
- interfacial bonding strength /
- first principle /
- line defect ratio
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