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.

Ta₂O₅ coatings were prepared on highly transparent quartz glass and silicon wafer substrates using RF magnetron sputtering technology. Different flow rates (10%, 15%, and 20%) of N₂ were introduced during the sputtering process while keeping the total sputtering gas flow rate constant at 40 sccm. The effects of N₂ flow rate on the phase structure, micro-morphology, elemental composition, and optical properties of Ta₂O₅ coatings were investigated. The coatings were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), electron energy spectroscopy (EDS), and spectrophotometry. The results show that the phase composition of the coating is an amorphous structure when the sputtering gases are pure argon and nitrogen-argon mixed gases, respectively. The coating after the passage of N₂ is mainly composed of Ta, N, and O, which confirms that the deposited coating is a composite coating of Ta oxide and nitride. The EDS spectrum indicates that the ratio of O to Ta atoms in the composite coating is greater than the stoichiometric value of 2.5. It may be related to the deposition rate of Ta atoms during the preparation process. The optical properties show that the average transmittance of the composite coating is greater than 75% and the maximum light transmission is 78.03%. The transmittance in the visible range of Ta₂O₅ coatings prepared under nitrogen-argon mixed gas sputtering conditions is greater than that of those prepared under pure argon sputtering conditions. Finally, the coatings optical direct band gap E_dg and indirect band gap E_ig are obtained.

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.

The accuracy of the end-effector motion trajectory is a critical performance indicator for cable-driven parallel mechanisms. This study aims to address the problem of trajectory error during the end-effector motion in a cable-driven parallel mechanism. It proposes a comprehensive compensation method based on the simultaneous application of the improved sparrow search algorithm and the cable length space error compensation algorithm, leveraging kinematic analysis. To compensate for the motion trajectory error of the end-effector caused by the geometric parameter error, the study establishes the kinematic model of the cable-driven parallel mechanism using the vector method. It creates the end-effector position error model and motion trajectory error model using the differential kinematic theory, analyzes the impact of the geometric parameter error on the motion trajectory error, constructs the kinematic parameter identification matrix, and uses an improved sparrow search algorithm to compensate for the position error of the motion trajectory interpolation point. For the motion trajectory error of the end-effector caused by non-geometric parameter error, the study analyzes the intrinsic correlation between the adjacent position error of the end-effector and the variation of the cable length using the error similarity theory. It then compensates for the position error of the interpolation point of the trajectory using a cable length space interpolation compensation method to enhance the motion trajectory accuracy of the end-effector. The study experimentally verifies the proposed comprehensive compensation method for end-effector motion trajectory error on a 4-cable-driven 2-DOF parallel mechanism, which reduces the motion trajectory error of the end-effector by 75%.

WS₂ films exhibit excellent tribological properties in a vacuum, but they are prone to failure due to oxidation in air, which severely limits their application. Cu has great potential to improve the tribological properties of WS₂, similar to that of Au and Ag. Thus, to clarify the contribution of Cu to the tribological properties of WS₂ films and provide new insight for the development of new multi-environmentally adaptable films, this study deposited WS₂-Cu composite films under different sputtering powers of the Cu target by magnetron sputtering systems, and the Cu target was supplied by DC power. Then, the structure of films was analyzed by FESEM, EDS and XPS. The results show that Cu is difficult to uniformly dope on the WS₂ film at a high sputtering power of Cu target, showing possibly low solubility of Cu in WS₂ film. However, a uniform and dense WS₂-Cu composite film was deposited under the lower sputtering power of Cu target. Furthermore, the results of the nanoindentation test demonstrated that the WS₂-Cu composite films exhibited high hardness (6.6 GPa). Finally, the tribological properties of the WS₂-Cu films were examined, and their friction interface was characterized by SEM, EDS and TEM. The WS₂-Cu film demonstrated superior tribological behavior in air (the average friction coefficient is 0.09), based on a special sliding interface, low oxidation levels of WS₂ and Cu-rich transfer film. This study provides a new insight and a new method for improving the environmental adaptation ability of WS₂ film.

Ta₂O₅ was deposited on quartz glass and Si substrates as a protective coating. The inherent RF magnetron sputtering power of 140 W was maintained during the deposition process. During the deposition process, amounts of 5%, 10%, and 15% of N₂ were injected, and the total sputtering gas (N₂+Ar) flow was kept at 40 sccm. The microstructure and surface morphology of the coatings were characterized, and the friction and wear experiments of the coatings were carried out. The results show that the coatings’ surface is smooth and the main chemical compositions are Ta, O, and N. The maximum average roughness of the coatings was prepared by pure argon sputtering. It is proved that the introduction of N₂ reduces the surface roughness of the coatings and increases the surface hardness and elastic modulus of the coatings. Adhesive wear and brittle fracture are the two main wear forms of coatings. The wear debris is mainly composed of columnar particles and a flake structure.