In preparing MoS₂-based coatings by magnetron sputtering, the working pressure of the vacuum chamber directly affects the number and kinetic energy of sputtering particles, which causes a difference in coatings structure and performance. In this paper, MoS₂ composite coatings with Ce and Ti binary doping were prepared by unbalanced magnetron sputtering technology, and the variation of composition, structure, and tribological properties of Ce-Ti/MoS₂ coatings under different working pressures was studied. The results demonstrated that Ce and Ti doping improves pure MoS₂ coatings. The Ce-Ti/MoS₂ coatings reached the hardness of 9.02 GPa and the friction coefficient of 0.065 when working pressure was at 0.6 Pa. It was also observed that the deposition efficiency and wear rate reached the optimal value at 0.9 Pa. With the increase of working pressure, the columnar structure of the coating was coarse due to the change of kinetic energy and quantity of particles in the chamber. The intensity of the MoS₂ (002) diffraction peak decreased, which eventually led to a poor lubrication effect and aggravated wear. This study provides technical guidance for preparing metal-doped MoS₂ composite coatings with excellent mechanical and tribological properties.

Exploring the doping components of the coating is of great significance for improving the tribological properties of the MoS₂-based coating. The optimization of magnetron sputtering process parameters can also improve the coating quality. In this paper, the effects of working gas flow rate on the microstructure in a vacuum chamber, nano-hardness, and tribological properties of Ce-Ti/MoS₂ coatings were studied using DC and RF unbalanced co-sputtering technology. It is found that the coating structure was coarse and porous when the Ar flow rate was excessive (70 sccm), significantly affecting the mechanical properties; there are pit defects on the surface of the coating when the flow rate is just minor (30 sccm), and the coating easily falls off during the friction process. When the flow rate is 40~60 sccm, the coating grows uniformly, the hardness reaches 7.85 GPa at 50 sccm, and the wear rate is only 4.42 × 10⁻⁷ mm³ N⁻¹ m⁻¹ at 60 sccm. The coating doped with Ce and Ti is an approximate amorphous structure. Under appropriate gas flow rate conditions, the friction induces a transfer film with a layered structure, and the MoS₂ (002) crystal plane orientation is arranged in parallel at the edge of the wear debris, effectively reducing the shear force during sliding and reducing wear. Based on rare earth doping, this study improves the tribological properties by optimizing the working gas parameters, which plays a reference role in preparing high-quality MoS₂-based coatings.

Adding alloying elements to binary nitrides enables the design of hard and tough coatings. To improve the mechanical and tribological performances of TiN-based coatings, La atoms were added to TiAlN coatings to form TiAlLaN coatings. Magnetron sputtering was conducted to prepare the TiAlLaN coatings. Thereafter, scanning electron microscopy (SEM), x-ray diffraction (XRD), nano-indentation, and a tribometer were utilized to test their microstructure, phases, and mechanical and tribological performances. Next, this study analyzed how lanthanum affected the microstructure and tribological performances of the TiAlLaN coatings. Incorporating La atoms in TiAlN coatings reduced the crystallite size and enhanced the coating toughness and hardness. The hardness H and elastic modulus E of the TiAlLaN coatings first increased and then decreased with the increase in La. Meanwhile, the coatings had improved wear and friction properties. The increased H/E and H³/E² levels, which have been considered to reflect the hard coating’s toughness, were acquired based on the TiAlLaN coating, possessing enhanced hardness (19.8 GPa). The coefficient of friction and the wear rates of the coatings reduced and then increased with the increase in La. The TiAlLaN coating with 1.4 % of lanthanum had the lowest friction coefficient and wear rate of around 0.383 and 1.59 × 10⁻⁸ mm³/N·m, respectively, corresponding to a higher H/E (~0.086) and H³/E² (~0.147 GPa). Adding an appropriate amount of La can substantially enhance the TiAlN coating’s tribological and mechanical properties. The TiAlLaN coating with remarkable characteristics may be applied to a steel substrate.