Surface Roughness Influence on Tribological Behavior of HiPIMS DLC Coatings

AbstractThe application of diamond-like carbon (DLC) coatings in dry machining of difficult-to-machine materials has been gaining popularity due to high inertness, low coefficient of friction (COF), and high hardness of these coatings. Although the effect of surface roughness on the tribological properties of DLC coatings is of paramount importance, usually it is overlooked and coatings performance analysis was accomplished generally on highly polished substrates. The generation of polished surfaces is a time-consuming, labor-intensive process and, in most cases, not feasible for the industry due to its high cost. This article focuses on determining the effect of substrate (cemented carbide, WC-Co) surface roughness on the load-bearing capacity and tribological properties of DLC coatings deposited by High Power Impulse Magnetron Sputtering (HiPIMS) in Ne–Ar gas plasma. The DLC films were deposited onto WC-Co substrates with three different surface roughness profiles and their tribological performance were evaluated using a reciprocating tribotest. The high surface roughness resulted in increased wear rate due to high levels of asperities and increased potential for premature delamination of the coatings, while also causing severe damage to the counterbody due to inhibition of transfer film formation.Keywords: Coefficient of frictionwearWC-Co substratesurface roughnessHiPIMSDLC coating AcknowledgementsThe authors acknowledge Sandvik Coromant AB, Sweden, for providing the cemented carbide (WC-Co) substrate for this work. We also thank Alireza Vahidi for assistance in the deposition of DLC coatings. The authors would like to thank Dr. Todor Vuchkov at Instituto Pedro Nunes (IPN) for help with white light interferometry.Conflict of InterestThe authors report there are no competing interests to declare.Additional informationFundingThe project received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 860246. This research was sponsored by national funds through FCT–Fundação para a Ciência e a Tecnologia, under projects UIDB/00285/2020 and LA/P/0112/2020.