Hard and well-adherent DLC coatings deposited by HiPIMS in Deep Oscillations Magnetron Sputtering (DOMS) mode.

Diamond-like carbon coatings (DLC) make up the largest proportion of coating solutions applied in the automotive industry, notably for engine applications, drivetrain components and transmission parts. DLC combine high hardness with low friction coefficient, chemical inertness, high thermal conductivity and high refractive index. In order to comply with the current trends of rising operating temperatures and lower viscosity oils, component manufacturer are currently seeking to develop a new generation of DLCs coatings, with improved properties. The main limitations of the existing DLC solutions stem from high internal stresses and limited thermal stability. The stresses, often in excess of 10 GPa, limit the maximum achievable thickness of hard DLCs due to adhesion problems. The main objective of this work is to develop a new generation of significantly improved well-adherent and hard DLC coatings, with high sp3/sp2 ratio and good temperature stability. DLC films were deposited by deep oscillation magnetron sputtering, a variant of high power impulse magnetron sputtering. The bombardment energy was controlled by changing the substrate bias. In order to improve the film’s adhesion an interlayer was deposited. In this work, the microstructure and mechanical properties of the films were characterized using scanning electron microscopy, Raman spectroscopy, X-ray reflectivity, nanoindentation.