单晶硅纳米切削中C—C键断裂对金刚石刀具磨损的影响  

Effect of C—C bond breakage on diamond tool wear in nanometric cutting of silicon

作　　者：王治国[1] 张鹏[1] 陈家轩[1] 白清顺[1] 梁迎春[1] 

机构地区：[1]哈尔滨工业大学机电工程学院,哈尔滨150001

出　　处：《物理学报》2015年第19期341-348,共8页Acta Physica Sinica

基　　金：中国博士后科学基金(批准号:2013M541362);黑龙江省自然科学基金(批准号:E201308)资助的课题~~

摘　　要：本文基于分子动力学方法模拟金刚石刀具纳米切削单晶硅,从刀具的弹塑性变形、C—C键断裂对碳原子结构的影响以及金刚石刀具的石墨化磨损等方面对金刚石刀具的磨损进行分析,采用配位数法和6元环法表征刀具上的磨损碳原子.模拟结果表明:在纳米切削过程中,金刚石刀具表层C—C键的断裂使其两端碳原子由sp3杂化转变为sp2杂化,同时,表面上的杂化结构发生变化的碳原子与其第一近邻的sp2杂化碳原子所构成的区域发生平整,由金刚石的立体网状结构转变为石墨的平面结构,导致金刚石刀具发生磨损;刀具表面低配位数碳原子的重构使其近邻区域产生扭曲变形,C—C键键能随之减弱,在高温和高剪切应力的作用下,极易发生断裂;在切削刃的棱边上,由于表面碳原子的配位严重不足,断开较少的C—C键就可以使表面6元环中碳原子的配位数都小于4,导致金刚石刀具发生石墨化磨损.It is well known that diamond is one of the most ideal cutting tool for materials, but the rapid tool wear can make surface integrity of the machined surface decline sharply during the nanometric cutting process for a single crystal silicon. Thus, a research on the wear mechanism of the diamond tool is of tremendous importance for selecting measures to reduce tool wear so as to extend service life of the tool. In this paper, the molecular dynamics simulation is applied to investigating the wear of the diamond tool during nanometric cutting for the single crystal silicon. Tersoff potential is used to describe the C—C and Si—Si interactions, and also the Morse potential for the C—Si interaction. The rake and flank faces are diamond （111） and （ˉ1ˉ12） planes respectively. A new method, by the name of 6-ring, is proposed to describe the bond change of carbon atoms. This new method can extract, all the worn carbon atoms in diamond tool, whose accuracy is higher than the conventional coordination number method. Moreover, the graphitized carbon atoms in the diamond tool also can be extracted by the combination of these two methods. Results show that during the cutting process, the C—C bond’s breaking in the surface layer of the diamond tool leads to the transformation of hybrid structure of the carbon atoms at both ends of the broken bond, from sp3 to sp2. Following to the bond breaking, the bond angle between the surface carbon atoms increases to 119.3° whose hybrid structure has changed, and the length between nearest neighboring atoms quickly decreases to 0.144 nm, indicating that the space structure formed by these carbon atoms has changed from 3D net structure of diamond to plane structure of graphite. Hence, the carbon atoms in the tool surface whose space structure has changed due to bond breaking should be defined as worn carbon atoms, but not only the carbon atoms whose hybrid structure has changed. The structure defects at both edges of the diamond tool are much more serious, which make the

关 键 词：分子动力学 纳米切削 金刚石刀具磨损 6元环法 

分 类 号：TG71[金属学及工艺—刀具与模具] TG501