Surface modification of 6150 steel substrates for the deposition of thick and adherent diamond-like carbon coatings

► In-situ low-temperature plasma carbonitriding followed by DLC deposition. ► The temperature was varied gradually just prior to DLC deposition. ► We obtained one-micron thick coating with hardness of about 18 GPa. ► Adhesion comparable to that obtained by a more elaborate process. ► This improved adhesion is due to the lower interfacial energy.