【摘要】 从原子量级揭示了金刚石刀具机械研磨过程中材料的去除机理——研磨过程中,研磨区域原子的相变是材料去除的主要原因.使用分子动力学方法建立了金刚石刀具和刚性金刚石磨粒的三维模型.采用Tersoff势函数计算了所有原子之间的作用力,并以1.5个晶格的切深进行了研磨过程模拟.通过观测模型内部原子位置的变化发现,研磨区域刀具原子的晶胞在研磨过程中被压扁,发生了从金刚石体心立方结构向无定形碳结构的转变.计算了研磨区域原子研磨前后的径向分布函数,进一步验证了该相变过程.同时,使用X射线衍射方法分析了研磨实验过程中产生的碎屑,分析结果表明研磨过程中确实有相变发生.更多还原

【Abstract】 The material removing mechanism for mechanical lapping of diamond cutting tools was illuminated at the at- omistic scale. In lapping process,phase transformation of the lapping region was the main reason for the material removal. Thus a three-dimensional model of a specimen of the diamond monocrystal and rigid diamond grit was built with the aid of the molecular dynamics(MD)simulation. The force between all of the atoms was calculated by the Tersoff potential. After that,lapping with a certain cutting depth of 1.5 lattice constants was simulated. By monitoring the positions of atoms within the model,the microstructure in the lapping region changes as diamond transformed from its diamond cubic structure to amorphous carbon were identified. The change of structure was accomplished by the flattening of the tetrahedron structure in diamond. This was verified by comparing the radial distribution functions of atoms in the lapping and un-lapping regions. Meanwhile,the debris produced in lapping experiment was analyzed by XRD(X-ray diffraction). The results show that the phase transformation happens indeed.更多还原