Bonding and sliding wear behavior of diamond-like carbon coatings on fiber reinforced aluminum

Abstract

The deposition of the outstanding chemical and tribological resistant diamond-like carbon (DLC) films on the stiff and strong carbon fiber-reinforced aluminum offers the possibility to tailor an extreme lightweight, strong and wear-resistant material. In this study attention is given to the characterization of mechanical and tribological properties of DLC films on metal matrix composites (MMCs). In addition, the adherence of the DLC to the heterogeneous substrates is demonstrated by using the scratch test. For comparison, the sliding wear behavior of the unreinforced aluminum and the uncoated MMC were investigated in detail as well. The sliding wear resistance is increased due to the reinforcement with carbon fibers. The orientation of the anisotropic fibers strongly determines the wear behavior of the uncoated MMCs. The DLC films have an average hardness of between 16.5×103 and 21.8×103 N mm−2, and the sliding wear resistance of DLC-coated MMCs is about one order of magnitude higher than uncoated MMCs. Also the orientation of the fibers influences the properties of the DLC film. In general the perpendicular orientation of the fibers to the surface effects the most improved sliding wear resistance of the uncoated MMCs as well as of the DLC-coated materials. Finally, it was found that for wear protection under higher contact loads, MMC substrates deliver a more effective coating support than the relatively soft unreinforced aluminum.