Abstract
High-power impulse magnetron sputtering (HiPIMS) is a plasma-based deposition process capable of significantly enhancing the ionization of sputtered species. The resulting ion bombardment of the substrate and the growing film during the sputtering-based process enables the synthesis of diamond-like carbon (DLC) films exhibiting both high hardness and excellent surface smoothness. However, in HiPIMS discharges the ion flux is typically dominated by Ar ions, and the associated energetic ion bombardment can cause significant substrate heating during deposition process. Such thermal effects may promote the formation of a graphite-like structure within the DLC films, thereby limiting the achievable film hardness. In this study, a substrate cooling system was implemented during HiPIMS deposition process by circulating coolants through a hollow sample holder. The effects of the substrate temperature on the surface roughness, hardness, internal film structure, and tribological properties of the DLC films were systematically investigated. The results show that substrate cooling effectively suppressed the formation of graphite domains within the films, thereby resulting in increased film hardness and improved wear resistance. These findings demonstrate that precise control of the substrate temperature is a critical factor for achieving high-hardness DLC films growth in HiPIMS deposition.
