Smooth diamond-like carbon films prepared by cathodic vacuum arc deposition with large glancing angles

Diamond-like carbon (DLC) films were prepared by cathodic vacuum arc (CVA) deposition with different glancing angles (the angle between the normal reverse direction of the arc target and the normal direction of the substrate surface) in range of 0 to 135°. The effects of the glancing angle on the morphology, carbon structure, mechanical property and tribological behavior of the DLC films were investigated. The results show that the surface quality of the DLC films is significantly improved by increasing the glancing angle. The macroparticles in the surface as well as the surface roughness of the DLC films decrease sharply as the glancing angle increases. The sp3/sp2 of the DLC films decreases at first and then increases as the glancing angle increases. The normal incidence energy of the Cn+ species becomes suitable to the formation of sp3-C when the glancing angle is 45°. The variation in the film hardness and compress stress at different glancing angles are similar in profile to the sp3 bond fractions. However, the compressive stress of the films could be reduced effectively by avoiding the bombardment of the Cn+ species with excessively high energy through increasing glancing angle. The tribological behaviors of the films could be also improved by changing the glancing angle. It is supposed that the CVA with appropriate glancing angle might be one way to prepare the DLC films with smooth surface, high hardness, low compressive stress and good tribological performance.