Phase Change of Carbon Atoms in Surface Layer Under Nanocutting During Diamond Lapping Process

Abstract

Lapping is still an efficient and economical way in diamond shaping process, which is important in both industrial and scientific applications. It has been known that the material removal originates from the phase change or amorphization of diamond crystal carbon atoms that are chemically activated by stress, forming a top layer of amorphous carbon atoms. In this paper, the phase change of amorphous carbon atoms undergoing the nanocutting of amorphous layer during diamond lapping process is studied by molecular dynamics (MD) simulation. Two regions, the debris layer and cutting surface underneath, are studied. In the debris layer, the change of sp2 carbon atoms is directly affected by impact, while underneath the cutting surface the changes of carbon atoms are almost not affected; the change speed of amorphous carbon atoms is higher than that of pristine crystal ones; the main phase change is transformation of sp3 into sp2; cutting depth to different extent affects the phase changes of sp3 and sp2 carbon atoms. Our study expands the understanding of diamond lapping process.