Investigation of structure and tribological behavior of nanostructured DLC coating, deposited by PACVD and Arc-PVD processes

In this Study, PACVD (plasma assistant chemical vapor deposition) and Arc-PVD (cathodic arc physical vapor deposition) methods were used to deposit of DLC (diamond like carbon) on St37 steel. Then, an interlayer was performed before applying the main DLC coating using arc-PVD. Field emission scanning electron microscopy, x-ray diffraction, Raman spectroscopy, energy dispersive spectroscopy, adhesion and tribological tests were performed to characterize and evaluate of coatings. Many factors are responsible for the excellent wear and mechanical behaviors of the DLC PVD coating including the presence of TiCrAlN interlayer, the fine grains (30-40 nm), hardness gradient as well as Ti and Cr carbides. These factors, also led to reach the high adhesion for this coating. The grain size of DLC PACVD coating was measured approximately 70-110 nm. In addition the thickness of arc-PVD coating was less than that of the PACVD coating which caused lower internal stress and subsequently appropriate adhesion to the substrate. The results revealed that this coating had lower hardness and adhesion to the substrate than that of the DLC PVD.