摘要
T-carbon is a new allotrope of carbon materials,and it displays high hardness and low density.Nevertheless,the hardening mechanisms of T-carbon thin films under nanoindentation remain elusive.This work utilizes molecular dynamics simulation to explore the hardening mechanisms of T-carbon thin films under nanoindentation with variations of loading velocities and temperatures.The results reveal that a loading velocity increase at a given temperature raises the nanoindentation force.The increase in nanoindentation force is due to graphitization,which is related to the fracture of tetrahedral structures in T-carbon thin films.However,increased graphitization caused by an increased temperature lowers the nanoindentation force at a given loading velocity.The increased graphitization is influenced by both the fractured tetrahedrons and the deformation of inter-tetrahedron bond angles.This is attributed to the loss of thermal stability and the lower density of T-carbon thin films as the temperature increases.These findings have significant implications for the design of nanodevices for specific application requirements.
T-碳是一种新型的碳材料同素异形体,具有高硬度、低密度的特点.然而T-碳薄膜在纳米压痕下的硬化机制仍不清楚.本文利用分子动力学模拟研究了纳米压痕下T-碳薄膜在加载速度和温度变化下的硬化机制.结果表明,在一定温度下,加载速度的增加会增加纳米压痕力.纳米压痕力的增加是由于石墨化,这与T-碳薄膜中四面体结构的断裂有关.然而,在给定的加载速度下,温度升高引起的石墨化增加会降低纳米压痕力.石墨化程度的提高受四面体断裂和四面体间键角变形的影响.这是由于随着温度的升高,T-碳薄膜的热稳定性丧失和密度降低.这些发现对于设计特定应用需求的纳米器件具有重要意义.
