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.

Based on the cohesive zone model (CZM), a finite element model of the film–substrate bearing system in the rolling–sliding contact state is established. Through analyzing the normal and tangential bearing states of the film–substrate system, the effects of the sliding–rolling ratio and the film–substrate adhesion strength on the interfacial stress and the interfacial energy release rate of the film–substrate system are studied. The results show that there is an almost symmetric stress distribution at both sides of the contact zone in rolling contact. In rolling–sliding contact, obvious shear flow along the rolling–sliding direction occurs at the front edge of the contact zone, which results in a significant increase in the shear stress at the interface at the front edge of the contact zone, increasing the risk of interface damage and delamination failure. Meanwhile, the shear flow causes a normal tensile stress concentration along the film surface behind the contact zone, which very easily causes the emergence and expansion of the film surface cracks. In addition, there is a clear positive correlation between the adhesion strength and the load-bearing capacity of the film–substrate interface. The tangential delamination damage mainly occurs at the interface regardless of the rolling or rolling–sliding contact state.

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.

MoS 2 -based self-lubricating coating many excellent properties and has broad application in aerospace and civil fields. MoS 2 coating is loose and easy to be oxidized at high temperatures and humidity. Since rare earth elements have the effect of inhibiting grain growth and coarsening in the material， Ti doping has been widely proven to effectively regulate the coating structure. In order to solve this problem， the influence of Ce-Ti alloy target power on tribological properties of MoS 2 -based coatings is investigated to prepare MoS 2 -based self-lubricating coatings with excellent dry friction properties. The influence of the power of the alloy on the microstructure， mechanical properties， and tribological properties of Ce-Ti /MoS 2 coating is studied by dc and RF dual-target non-equilibrium co-sputtering technology. The doping content of the coating is controlled by adjusting the power of the Ce-Ti （1:1） target. The composition， crystal phase structure， and microstructure of the coating are analyzed by field emission scanning electron microscopy （FESEM）， energy dispersive spectroscopy （EDS）， atomic force microscopy （AFM）， and grazing incidence X-ray diffraction （GIXRD）. The mechanical properties of the coating are tested by nano indentation apparatus. The friction and wear properties of the coating are characterized by friction and wear testing machine， white light interferometer， and Raman spectrometer. The composition changes of the coating surface and wear marks are analyzed. The coating initially grew in （002） preferred orientation， accompanied by （100）， （105） and （110） three growth orientation MoS 2 characteristic peaks. With the increased power of the doped metal， the crystal structure of the MoS 2 coating becomes similar to the amorphous structure. The surface changes from pure MoS 2 vermicular shape to fine aggregate shape gradually， and the aggregate size becomes coarse after reaching 90W power. The friction coefficient and wear rate decreased first and then increased. When the deposition power of Ce-Ti target reaches 70W（Ce:2.32at.%， Ti:7.21at.%）， the densification of Ce-Ti target changes from undoped porous columnar crystal to fine columnar growth structure， the nano-hardness reaches 7.85GPa， and the oxidation phenomenon is obviously improved. In terms of friction and wear， the wear scar shows micro abrasive wear at 70W power， the average friction coefficient is as low as 0.073， and there is no apparent sharp increase. In the process of friction， the coating did not produce evident adhesion and plastic fracture， and the wear rate was reduced to 9.42×10 -8 mm 3 N -1 m -1 . The steel balls formed transfer films， which effectively reduced the shear force in the friction process. Under the condition of 70W， the area of transfer film is the smallest， which slows down the adhesion between interfaces. The MoS 2 structure is reconstructed at the wear scar during friction， which significantly reduces material’s friction coefficient and wear rate. Magnetron sputtering Ce-Ti doped MoS 2 based coating improves the compactness and friction and wear performance of the coating and achieves the optimal comprehensive performance when the power is up to 70W， and the friction coefficient and wear rate of the coating is significantly reduced.

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.

针对TiAlN薄膜耐磨性不够优异的问题,研究了Al质量分数对Ti1-x Alx N薄膜结构和摩擦学性能的影响.采用磁控溅射沉积技术制备了4种不同Al质量分数的Ti1-x Alx N薄膜.利用扫描电镜(SEM)、能谱仪(EDS)及X射线衍射仪(XRD),对薄膜的微观形貌、元素成分与晶体结构进行了表征.采用纳米压痕仪测试薄膜的硬度和弹性模量,用摩擦磨损试验机和白光干涉三维形貌仪测试薄膜的摩擦磨损性能.研究结果表明:随着Al质量分数在一定范围内的增加,薄膜从沿c-TiN(111)晶面生长逐渐转向h-AlN(200)晶面择优取向,Ti1-x Alx N薄膜疏松结构得到了改善,柱状结晶发生细化,表面形貌更加致密.同时,Ti1-x Alx N薄膜的硬度和弹性模量得到提高,磨损机理由严重的磨粒磨损、黏着磨损转变为轻微的磨粒磨损,平均体积磨损率降低.Ti0.67 Al0.33 N薄膜的综合性能最优,硬度和弹性模量分别为14.059 GPa和203.37 GPa,摩擦因数最低为0.182,平均体积磨损率为1.321×10-8 mm3/(N·m),呈现出较好的摩擦学性能.