Multilayer diamond-like amorphous carbon coatings produced by ion irradiation of polymer films

Diamond-like carbon (DLC) is known to be a versatile coating material, being found in a wide variety of surface engineering applications. In this study, we produced DLC coatings by ion irradiation and thus reconstruction of a thin polymer film. This procedure leads to a thin diamond-like carbon layer which is characterized by its high hardness. Due to the finite ion range during implantation, however, the maximum thickness of such coatings is limited. Nevertheless, several applications for DLC coatings demand a larger thickness. We thus increased the thickness of such DLC coatings by repeatedly applying the deposition and transformation process, thus creating thicker multilayers. We show that their physical and mechanical properties like roughness, nano-hardness, sp3 fraction as well as the very important adhesion of thick DLC films produced this way are very well suited for the desired applications. Although we find a small decrease in hardness and a little bit less sp3 fraction with increasing coating thickness, our results exhibit a typical hardness as well as sp3 fraction for a-C:H even for the largest coating thicknesses produced so far.