Probing the Stress Reduction Mechanism of Diamond-Like Carbon Films by Incorporating Ti, Cr, or W Carbide-Forming Metals: Ab Initio Molecular Dynamics Simulation

• Published in: Journal of physical chemistry. C Vol. 119; no. 11; pp. 6086 - 6093
• Main Authors: Li, Xiaowei, Ke, Peiling, Wang, Aiying
• Format: Journal Article
• Language: English
• Published: American Chemical Society 19-03-2015
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.5b00058

Ab initio molecular dynamics simulation based on density functional theory was performed to investigate (Ti, Cr, or W)-incorporated diamond-like carbon (DLC) films. The structure models were generated from liquid quench containing 64 atoms. The dependence of the residual compressive stress, bulk modulus and tetra-coordinated C content on the Ti, Cr, and W concentrations in the range of 1.56 to 7.81 atom % was studied. The present simulation results reveal that the residual stress strongly depends on the incorporated Ti, Cr, and W atoms. With the incorporation of Ti at 1.56 atom %, Cr at 4.69 atom %, and W at 3.13 atom % to DLC films, the compressive stress was reduced by 46.9%, 81.4%, and 82.5%, respectively, without obvious deterioration of the mechanical properties. However, at higher Ti, Cr, and W concentrations, the compressive stress increased for each case, which was consistent with the experimental results. Structural analysis using both the bond angle and bond length distributions indicates that the small amount of Ti or W incorporation efficiently relaxes both the highly distorted bond angles and bond lengths, whereas the Cr incorporation only relaxes the distorted bond lengths, which decreases the residual compressive stress and provides theoretical explanations for the experiments.