Electrodeposition and microstructure of Ni and B co-doped diamond-like carbon (Ni/B-DLC) films

Ni and B co-doped diamond-like carbon (Ni/B-DLC) films were synthesized on the surface of AZ91D magnesium alloy by electrodeposition under mild environment. The formation mechanism of Ni/B-DLC films was discussed. The microstructure of the films was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Results conveyed that the Ni-DLC and Ni/B-DLC films were hydrogenated amorphous carbon films. With the co-doping of Ni and B, the protruding mulberry-like structure of carbon-based films gave way to the compact and uniform granular structure. The intensity ratio (ID/IG) of D and G lines was decreased from 0.75 to 0.71. XRD patterns revealed that the doping of boron favored the sp3 hybridization of carbon atoms. Simultaneously, the infrared spectra demonstrated that hydrogen for Ni/B-DLC films was preferentially bonded with sp2 carbon atom. In addition, Ni/B-DLC films had excellent wear resistance, which was mainly attributed to the homogeneous and dense structure and considerable micro-indentation hardness. •Ni-DLC and Ni/B-DLC films were prepared by a simple electrodeposition route.•The formation mechanism of Ni/B-DLC films was explored.•With the doping of boron, the mulberry-like structure of the film was replaced by the dense and uniform granular structure.•Boron doping was beneficial to the sp3 hybridization of carbon atoms.•Hydrogen for Ni/B-DLC films was preferentially linked to sp2 site.