Abstract
Diamond-like carbon (DLC) films possess excellent tribological properties, such as low friction and high wear resistance. However, DLC films detach easily owing to the high residual stress, which limits their application on mechanical sliding surfaces. To overcome this problem, it is crucial to clarify the residual stress generation mechanism in DLC films. In this study, molecular dynamics simulations were conducted on the deposition process of a DLC film to clarify the residual stress generation mechanism. The results suggest that sp(3) hybridization clusters are nucleated in the sp(2) formed on the film surface, and sp(3) clusters grow in the sp(2 )carbon through the sp2 -> sp(3 )bond change during the film growth process. The bond length of sp(3) was approximately 8.5% larger than that of sp(2) under stress-free bulk conditions. Thus, when the sp2 -> sp3 bond change occurs under construction by surrounding atoms, compressive stress is generated in the sp(3) cluster, which increases with the growth of the sp(3) cluster. Based on the results, we conclude that the nucleation and growth of sp(3) clusters in sp(2) result in residual compressive stress in the DLC film. We believe that the present mechanism clarification of the stress development process in DLC films will facilitate the development of new methods for residual stress reduction.
NSTL
Elsevier