Influence of crystalline diamond nanoparticles on diamond-like carbon friction behavior

► The sp3/sp2 ratio slightly increased with the presence of CD particles. ► CD particles reduce DLC average friction coefficient by the formation of low-shear microfilms on the coating or by the asperity tips of the coating. ► DLC films with particles of 4 nm presented the most homogeneous friction map, with minor variation in friction coefficient with the increase/decrease of load and sliding speed, even when the nanoparticle concentration increase.