【作者】 周晖；

【导师】 薛德胜；

【作者基本信息】 兰州大学 ， 材料物理与化学， 2007， 博士

【摘要】 尽管溅射沉积MoS₂薄膜已成为星上精密活动件表面润滑改性的主要手段之一，但是当前的薄膜制备技术依然存在大气防潮能力低、真空环境中耐磨寿命不够长以及复杂形状活动件表面均匀成膜、批量生产困难等缺陷。为了满足我国空间飞行器后续发展对功能扩展、寿命提高以及研制周期缩短提出的工程应用急需，本研究采用近年来新开发的非平衡磁控溅射沉积技术，并通过在MoS₂薄膜中掺杂金属Ti有效地弥补了当前制备技术的缺陷，提高了薄膜的性能。本文重点研究了薄膜制备工艺参数变化对其结构和性能的影响及作用机理，最终获得了优化的工艺并达到了工程应用水平。研究工作取得的主要创新性结果如下：1、首次系统、细致地研究了溅射靶功率、非平衡磁控线圈电流、工件台偏压、工作气体流量、工件台转速、薄膜沉积温度、沉积时间多项工艺参数与薄膜的结构和性能之间的关系，对变化机理进行了深入的分析和探讨，掌握了优化的薄膜制备工艺。2、首次阐明在大气和真空环境中，使MoS₂-Ti复合薄膜具有润滑能力的允许Ti含量不同，大气环境为17～20 wt．％，真空为12～15 wt．％，大气中允许的Ti含量较高与氧存在下摩擦对偶间形成Fe₂O₃和MoO₃，从而有利于MoS₂转移膜的形成以及加强了转移膜与摩擦对偶间的附着力有关。3、首次提出通过薄膜硬度以及附着力测试图片来预测其在真空环境中的摩擦学性能，当薄膜纳米压入硬度高于5 GPa或附着力测试图片上的划痕表现为锯齿状崩落时，薄膜在真空环境中的耐磨寿命差甚至失去润滑能力，产生的机理是在加强的离子流轰击作用下薄膜颗粒尺寸不断减小以致破坏了MoS₂晶间和晶内的滑移能力。4、开展了试验条件与薄膜真空摩擦学性能的关系研究，获得了多种试验载荷、转速、基底材料、表面处理状态下薄膜的真空耐磨寿命，发现转速在250～1000 r／min内变化时薄膜耐磨寿命基本不变，从而提出可利用此特点对经该工艺润滑的活动机构开展有效的加速寿命试验。5、首次证明该工艺在空间精密滚动轴承上具有较好的适用性，获得了在30℃，85％相对湿度环境中贮存1年以上轴承各项摩擦力矩变化的数据，以及在优于10^-3Pa级真空环境中沿同一方向累计运转1.8×10⁸转以上的寿命试验数据，为该项技术在空间精密活动件中的应用提供了有力的支撑。更多还原

【Abstract】 Though magnetron sputtering MoS₂ films have already been used in aerospace precision moving mechanical parts as one of the main surface lubricating modification methods, there are still some deficiencies existed in current deposition technology. For example , film has poor humidity-resistant ability; in vacuum the wear resistant life of the film is not long enough; and for mechanical parts with complicated configurations the film can’t been deposited uniformly throughout the surface; additionally the current method has trouble on mass production. At present, spacecraft development on function expansion, life lengthening and manufacture periods shortening appeals to improve MoS₂ deposition technology to content their urgent engineering application needs. In this paper, we use unbalanced magnetron sputtering deposition system to obtain uniform MoS₂ film and by doping Ti in MoS₂ film to improve the film’s properties. The study is emphasized on the effects and mechanisms of the deposition parameters on the structure and properties of the film. Ultimately we got optimized technology parameters for producing high quality film which can meet the need of aerospace engineering application.The main results and innovations of this study are :1. For the first time, the systematic and detailed relationships and alteration mechanisms between structure, properties of MoS₂ film and deposition parameters such as target sputtering power, unbalanced magnetron coil current, substrate bias, gas flow during deposition, substrate table rotation, deposition temperature and time are acquired, and the optimized deposition parameters are procured.2. For the first time, we find that in ambient and in vacuum environments, the Ti content allowed to be doped in MoS₂ film is different if the film’s lubricating ability is maintained. In ambient environment, this value is between 17 wt.% and 20 wt.%; while in vacuum it is 12～15 wt.%. The result can be interpreted as in ambient environment , the oxidation of portions of MoS₂ to MoO₃ and Fe to Fe₂O₃ will promote the transfer of MoS₂ to opposite part and realize strong substrate-film-opposite part bonding.3. We find a simply method to predict film’s wear resistant life in vacuum by measuring film’s nano-indention and analyzing scratch testing pictures. If the film’s nano- indention hardness is above 5 GPa or if there are jagged scores in the scratch testing picture, the film will has poor wear resistant life or even has no lubricating ability. It is proposed that since the size of the crystallite in the MoS₂ film is so small at higher ion flux bombardment, the intercrystallite or innercrystallite slips in MoS₂ film are prohibited.4. The effects of test conditions such as load, speed and substrate on film’s tribological properties in vacuum are studied. We find that when test speed is changed between 250～1000 r/min, the film’s wear resistant life keeps almost the same, then space moving mechanisms used such lubricating method can have effective accelerated life test method.5. For the first time we indicate that such film deposition technology can be used on aerospace precision ball bearings. The test data show that the change of bearing’s friction torque in 30°C, 85% humidity environment which is beyond one year andthe bearing’s running properties in 10^-3 Pa grade vacuum which is beyond 1.8×10⁸ round. These experimental data can provide strong support for the application of the technology in space.更多还原