ISSN   1004-0595

CN  62-1224/O4

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MoS2基复合薄膜真空高温摩擦学性能及其机理研究

Tribological Properties of MoS2-Based Composite Films at Different Temperature in Vacuum and Its Mechanism

  • 摘要: 采用闭合场非平衡磁控溅射技术分别制备了纯MoS2薄膜以及MoS2-Ti和MoS2-Ti-TiB2复合薄膜,利用真空高温摩擦试验机对比考察三种薄膜在真空环境中25~300 ℃下的摩擦学性能,通过拉曼光谱(Raman)、X射线衍射(XRD)和透射电镜(TEM)等分析复合元素对薄膜结构的影响以及摩擦前后薄膜结构的变化,探讨摩擦磨损机理. 结果表明:纯MoS2薄膜以(002)和(100)晶面取向生长,结构疏松,硬度低,在真空不同温度下摩擦寿命很短;Ti和TiB2复合后,薄膜呈现致密的非晶结构,硬度升高;MoS2-Ti薄膜在低温下(25和100 ℃)下具有优异的摩擦学性能,当温度达到200 ℃以上时,摩擦寿命急剧降低;MoS2-Ti-TiB2复合薄膜在25~300 ℃全温度范围内都保持低的摩擦系数和磨损率,这与其致密的非晶结构、摩擦界面MoS2 (002)晶面有序化以及高硬度耐高温TiB2掺入有关;低温下薄膜以磨粒磨损为主,高温下以擦伤为主.

     

    Abstract: Molybdenum disulfide (MoS2) is an excellent solid lubricating material, which has been used extensively in space applications, because of its special structure. However, the resistance of MoS2 coatings against high temperatures is inadequate and the tribological properties of MoS2 coatings are degraded in high temperatures conditions, resulting in an increase of the friction coefficient and a decrease in its working lifetime. This paper aimed to improve the high-temperature resistance performance of Molybdenum disulfide and enable it to be used in a wide temperature range, the Ti and TiB2 were adoped in the MoS2 films, and the morpholgy, structure and tribology performance were investigated in detailed. Fristly, three kinds of films were successfully prepared by closed-field non-equilibrium magnetron sputtering technology, namely pure MoS2 films, MoS2-Ti composite films, and MoS2-Ti-TiB2 composite films. XRD and Raman spectroscopy were used to analyze the physical structure and composition of thin films, and the results demonstrated that the texture of the films changed from random mixed orientation with (002) and (100) planes of the pure MoS2 films to the preferred (002) orientation with the adoping of Ti, while the MoS2-Ti-TiB2 composite films were amorphous. The results of the Raman spectroscopy analysis indicated that the MoS2-Ti-TiB2 composite films had the the best ability of antioxidant than the other two kinds of films. The microstructure of the film was characterized by SEM and FIB-TEM, and the analysis showed that the surface of the pure MoS2 films were loosed, and that of the composite films were smooth and dense, and the cross section morphology were consistent with it. Thus, the hardness of the MoS2-Ti-TiB2 composite films were the highest, and the pure films with loose structure were the lowest. The tribological properties from 25 to 300 ℃ in vacuum environment were investigated by using a vacuum high temperature friction tester. The pure MoS2 film growed in (002) and (100) crystalline orientations had very short friction life at various temperatures (25~300℃) in vacuum. The MoS2-Ti films had excellent tribological properties at low temperatures of 25 and 100 ℃, however, the friction efficient and the wear rate were decreased dramatically when the test temperature beyond 200 ℃. Though the wear rate of the MoS2-Ti-TiB2 composite films were higher than that of MoS2-Ti films at room temperature, the wear rate and the friction coefficient of the MoS2-Ti-TiB2 composite films maintained low in the full temperature range of 25~300 ℃. That was mainly due to the dense amorphous structure of the composite film that prevented the diffusion of oxygen and the oxidation of the film. Besides, the morphology of the grinding crack showed that abrasive wear was the main mechanism for MoS2-Ti-TiB2 composite films at low temperature. At high temperature, a sliding interface with an ordered (002) crystal structure was formed during the friction process, and the friction mechanism was mainly scratch and interlayer transfer peeling.

     

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