权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

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.

类金刚石碳（DLC）膜主要由金刚石中的sp^3键原子和石墨中的sp^2键原子组成。有关其力学性能和摩擦学性能的研究已有很多报道，但对其变形机理的研究还不够深入。本文采用分子动力学方法研究了单轴载荷作用下键合形式的变化。通过随机游走法对DLC膜进行单轴拉伸分析，在拉伸下，sp^3键合原子的含量比sp^2键合原子的含量减少。观察到键合形态的变化，伴随着键合形式的湮灭和生成。通过这些变化，包括背键相互作用在内的局域原子环境在能量上趋于稳定。在形变作用下，原子间的弯曲和扭转效应比键的伸缩效应更为显著。然而，已有的Tersoff型势不能代表其扭转效应，这在考虑类非晶非均匀结构的变形时可能是一个致命的缺陷。因此，阶（N）紧束缚分子动力学方案（O（N）TB-MD）的应用，以阐明这些问题在下一阶段。采用密度矩阵方法作为N阶标度，在保持原子间力作为势能的一阶梯度和弹性刚度作为二阶梯度的合理精度的前提下，减少了大量的计算时间。结果表明，采用淬火工艺制备的初始类金刚石模型中sp^3的含量较高，这与实验结果吻合较好。扭转阻力对DLC膜的变形起着重要的作用。