Interatomic Description of Clustered Structure for Strength of Diamond-like-carbon Film

类金刚石碳膜强度簇状结构的原子间描述

基本信息

批准号：
11650092
负责人：
SHIBUTANI Yoji
金额：
$ 1.6万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

A diamond-like carbon (DLC) film is mainly composed of both sp^3 bonded atoms as in diamond and sp^2 bonded atoms as in graphite. Many reports concerning their mechanical and tribological properties have been published, while there are not enough studies on deformation mechanism yet. In the present research, the change of bonding form under uniaxial loading is investigated using the molecular dynamics. From uniaxial tension analyses of the DLC film obtained by the random walk method, the content rate of sp^3 bonded atom decreases as opposed to the one of sp^2 bonded atom under the tension. The morphological changes of bonding which are accompanied by the annihilation and the generation of the bonding forms are observed. By these changes, local atomic environment which includes the back-bond interaction comes to stabilize energetically. And, it is concluded that bending and torsion effects between atoms are more predominant rather than bond-stretching under the deformation. However, the well-established Tersoff type potential can not represent its torsion effect.The above-mentioned fact may be fatal defect when considering the deformation of the amorphous-like inhomogeneous structure. Therefore, Order (N) tight-binding molecular dynamics scheme (O(N)TB-MD) is applied to elucidate these problems at the next stage. The density matrix method as an Order (N) scaling is adopted to reduce the drastic computational time with keeping the reasonable accuracy of an interatomic force as the first-order gradient of the potential energy and elastic stiffness as the second-order gradient. It is found that the high content of sp^3 in the initial DLC model by quenching process is obtained, which is in good agreement with the experimental results. And the torsional resistance plays an important role in the deformation of the DLC film.

钻石样碳（DLC）膜主要由钻石中的Sp^3键合原子和Sp^2键合原子组成，如石墨中。有关其机械和摩擦学特性的许多报告已经发表，而对变形机制的研究还没有。在本研究中，使用分子动力学研究了单轴负荷下键合的变化。从随机行走方法获得的DLC膜的单轴张力分析中，Sp^3键原子的内容速率降低了，而不是张力下的Sp^2键合的原子之一。观察到伴随歼灭和粘结形式产生的键合的形态变化。通过这些变化，包括背键相互作用在内的局部原子环境可以稳定在能量上。而且，可以得出结论，原子之间的弯曲和扭转效应在变形下更为主导，而不是键拉伸。然而，建立的tersoff型电势不能代表其扭转效应。在考虑异形类不均匀结构的变形时，上述事实可能是致命的缺陷。因此，应用（n）紧密结合分子动力学方案（O（n）TB-MD）在下一阶段阐明这些问题。采用密度矩阵方法作为阶尺度（n）缩放，以减少剧烈的计算时间，以保持原子间力作为势能和弹性刚度的一阶梯度作为二阶梯度的一阶梯度。发现通过淬灭过程，在初始DLC模型中SP^3的高含量与实验结果非常吻合。扭转抗性在DLC膜的变形中起着重要作用。