Diamond-like carbon (DLC) coating on graphite: Investigating the achievement of maximum wear properties using the PECVD method

Abstract

Considering the potential for morphological changes and the adjustment of the sp3/sp2 ratio in diamond-like carbon (DLC) coatings, and consequently the possibility of adjusting the properties of self-lubricating, hardness, and wear of these coatings, the present study investigates the effect of varying the power applied during the deposition of coatings using plasma-enhanced chemical vapor deposition (PECVD) method. Raman spectroscopy, Atomic Force Microscopy (AFM), Field Emission Scanning Electron Microscopy (FESEM), nanoindentation, wear, and wear depth tests were employed for this purpose. The results obtained from the Raman spectroscopy indicated that the percentage of sp3 hybridization, as well as the amount of internal stress, increased with the higher applied power of the coating. AFM results also reveal an increase in surface roughness with increasing applied power, and FESEM results indicate a reduction in the diameter of DLC grains with increasing applied power. Moreover, the alternating increase in hardness and modulus of elasticity, along with a decrease in friction coefficient and wear depth, are among the other effects of increasing the applied power. Therefore, the results of this research suggest an enhancement in the tribological properties of the applied coating at higher powers (up to 250 W).