空间运动部件液体润滑加速寿命试验可行性分析

空间运动部件是航天器及其有效载荷的关键部件,液体润滑已在其中得到广泛应用,而液体润滑的失效机制和寿命分析是目前关注的问题。加速寿命试验是用加大试验应力的方法来缩减试验周期的一种试验方法,这可使得在短时间内对高可靠性长寿命的可靠性评定成为可能。讨论了油润滑条件下对航天运动部件的加速寿命试验的可行性、原则和方法,指出在油润滑中,在保证润滑状态不变的情况下,选择温度、转速为加速应力是可行的。     

湿度、温度及润滑油对粘结MoS2固体润滑涂层微动磨损寿命的影响

在不同载荷和位移幅值条件下．研究了湿度、温度及润滑油对粘结MoS2固体润滑涂层微动磨损寿命的影响。试验结果表明：湿度、温度的变化及润滑油环境下都会不同程度地影响粘结涂层的磨损寿命。相对湿度愈高,寿命愈低;温度的影响分两个阶段,20～100℃范围,磨损寿命随温度升高而增加,在100～300℃范围,磨损寿命随温度的升高而下降;润滑油的影响强烈依赖于位移幅值和载荷变化,低位移幅值、高载荷下影响极小,而高位移幅值、低载荷下将导致磨损寿命下降。     

空间相机扫描机构固体润滑轴承组件的寿命试验

开展了固体润滑轴承组件的真空加速寿命试验,以验证固体润滑轴承组件的设计是否满足在轨寿命要求。研究了MoS2基薄膜固体润滑轴承组件在小角度摆动情况下的寿命。试验采用4对轴承模拟在轨±6°连续往复摆动,通过检测轴承组件工作时的摩擦力矩、电机电流和轴承温升判断轴承运行状态。结果显示,寿命试验运行正常,累计摩擦次数为6.2×10~7次。寿命试验后对轴承进行了尺寸精度和旋转精度复测,然后对轴承组件进行了解剖分析。复测结果显示,轴承尺寸精度和旋转精度与试验前一致,轴承润滑状态良好。试验结果验证了固体润滑轴承组件寿命满足在轨任务要求,为其它空间相机小角度摆动的扫描机构固体润滑轴承组件的长寿命设计提供了依据。     

固体润滑轴承的寿命分析

通过对固体润滑轴承寿命理论和试验分析,得出要获得固体润滑轴承更长的寿命,则需使轴承实现转移膜润滑,而合适转移膜润滑的实现与保持架的稳定性、材料的磨损及工况条件等有着密切关系     

大气环境下溅射MoS_2/Ti膜708C角接触球轴承寿命试验

以溅射MoS2/Ti润滑膜的708C角接触球轴承为对象,在大气环境下通过施加不同轴向载荷进行寿命试验,研究轴向载荷对轴承润滑寿命的影响。结果表明,内圈沟底和球表面的磨损程度随着轴向载荷的增大而加剧,但内沟道侧面的磨损程度随着轴向载荷的增加而减弱,特别是施加60和70 N轴向载荷时,内沟道侧面润滑膜仍然比较致密,这可能与轴向载荷增大使轴承在运转过程中沿轴向的摆动幅度减小有关。     

空间合成碳氢润滑油的真空边界润滑寿命评估

为评估空间润滑油能否满足处于边界润滑工况下的扫描机构8年长寿命要求,分析润滑油在空间环境下的摩擦磨损和长寿命润滑性能。以空间合成碳氢润滑油RP4751为研究对象,分别采用真空螺旋摩擦试验系统(SOT)和滑动摩擦试验系统(SRV)测试润滑油的名义润滑寿命(每消耗1μg润滑油时钢球转动的圈数)、磨斑直径和滑动摩擦因数,结合扫描电子显微镜和X射线能量色散谱仪进行微观分析。结果表明:RP4751润滑油在真空环境下滑动摩擦因数较小、耐磨寿命较长,具有良好的真空边界润滑性能和较高的名义寿命;红外透过率分析结果表明,SRV试验前后润滑油未发生质变。利用2台RP4751润滑油润滑的扫描电机开展1∶1真空寿命试验,结果表明:RP4751润滑油润滑时电机寿命满足红外地球敏感器运动机构的8年在轨运行寿命需求;试验得到的电机轴承中的钢球润滑寿命大于等于2 943 r/μg,该结果与SOT试验的润滑油名义寿命3 598 r/μg有较好的一致性,为其他空间运动机构润滑油的选用及长寿命润滑设计提供重要试验依据。     

空间用合成碳氢润滑油的长寿命润滑特性分析

为评估空间润滑油在空间环境下的摩擦磨损和长寿命润滑性能,以空间碳氢润滑油RP4752为研究对象,分别采用真空螺旋摩擦试验机(SOT)和滑动摩擦试验机测试润滑油的名义润滑寿命、磨斑直径和滑动摩擦因数,结合扫描电子显微镜和X射线能量色散谱仪进行微观分析。结果表明:RP4752润滑油在真空环境下滑动摩擦因数较小,耐磨寿命较长,具有良好的真空边界润滑性能,试验前后润滑油的红外透过率在14～16.25μm波段无明显变化。在真空寿命验证试验中,两台采用RP4752润滑油润滑轴承的扫描电机旋转圈数达3.02×10⁸,满足运动机构8年在轨运行寿命的需求。此寿命试验结果与SOT试验的润滑油名义寿命每微克1 615圈可形成比对关系,为其他空间运动机构润滑油的选用及长寿命润滑设计提供试验依据。     

MoS2固体润滑轴承跑合技术实践

介绍了航天用MoS2固体润滑轴承润滑膜的结构和磨损机理,分析了跑合对该类轴承应用的重要性以及对润滑膜形貌和性能的影响.结合固体润滑轴承的跑合实践,总结并剖析了MoS2固体润滑轴承跑合过程中常见的问题及解决措施.采用变载荷跑合,用绸布擦拭清洗沟道,合理设定跑合参数,通过跑合带宽度均匀性评估跑合效果等能够有效改善固体润滑膜...     

三种固液复合润滑系统的真空边界润滑特性

为研究MoS2/815Z、MoS2/RP4751和MoS2/RIPP4758三种固液复合润滑体系在真空边界润滑工况下的润滑特性,对三种固液复合润滑体系进行了真空往复滑动摩擦试验和真空螺旋轨道摩擦(SOT)试验研究,并对SOT试验后的球盘摩擦副平盘表面进行扫描电镜(SEM)和X射线能量色散谱仪(EDS)分析.试验结果表明...     

反旋转弯曲载荷下V型切口棒料的疲劳寿命估算方法

针对应力下料的实际要求,介绍反旋转拉弯复合应力加载模型。提出带缺口棒料的疲劳寿命由始裂寿命和裂纹扩展寿命两部分组成的思想。在考虑V型切口棒料几何参数及材料拉伸性能影响基础上,给出裂纹起始寿命估算公式。通过分析裂纹扩展过程中应力比的变化规律,提出当量应力比概念,结合Walker公式得到反旋转弯曲载荷下带缺口棒料疲劳寿命估算公式。结合具体案例计算棒料疲劳寿命,与已有的反旋转应力下料方式实验结果对比,表明该估算公式预测结果精度高,具有较好的应用价值。     

Effect of discontinuous hard under-coating on the life of solid film lubricant under extreme contact pressure

Wear life of bonded molybdenum disulfide film lubricant applied on discrete sections of chromium electroplated to an aluminum alloy substrate under extreme contact pressure was investigated. Block-on-ring tests with ridge-shaped, hardened stainless steel blocks and lubricant coated rings were carried out in a nitrogen atmosphere for several kinds of ring materials including this under-coating. All tests except those for the discontinuous chromium under-coating indicated large or unstable friction soon after the tests started. Discontinuous chromium coating demonstrated a stable friction coefficient of around 0.05 for a long time and the lubricant film remained intact after the test. This is because discontinuous chromium coating on aluminum substrate deformed along the shape of the ridged-block and contact pressure was decreased to several hundred MPa.     

Modern solid lubrication: Recent developments and applications of MoS2

An important and growing field of lubrication lies in the use of solid films, although they are in general more expensive than oils or greases, and require specialist attention both in mechanical design and in coating application techniques. In this paper, the general classification of solid lubricant types is reviewed, along with the reasons for choosing, and methods of depositing, solid lubricants, in particular MoS₂. The best‐performing and most flexible technique for making MoS₂ films is by physical vapour deposition (PVD), and the variants of that technology are considered. The intrinsically lubricating, lamellar structure of pure MoS₂ is described, along with a brief summary of its wear and failure modes. Present applications for lubrication by MoS₂ in spacecraft and dry machining are outlined, as are anti‐adhesive uses in extruding and moulding. The current state of the art of modification of MoS₂ films consists in the addition of dopants (co‐sputtering), in multilayering as a series of films, each fulfilling a specific task, or in stacking repeating nano‐metre‐scale films. Composite films of MoS₂ islands in a hard film matrix are also being developed.     

The effect of space irradiation on the lubricating performance of perfluoropolyether greases in simulated space environment

In this paper, 2 kinds of commercial perfluoropolyether (PFPE) greases were coated on the polyimide (PI) blocks, which were placed within simulated space environment including atomic oxygen (AO), proton (Pr), ultraviolet (UV), and electron (El) irradiations, and then the tribological performance has been investigated with a ball‐on‐disc tribometer. Results indicated that the MoS₂‐grease showed better lubrication performance than the PTFE‐grease. The changes in infrared spectroscopy induced by Pr and El irradiations were more obvious than that by AO and UV irradiations. Results of energy dispersive X‐ray spectroscopy indicated that Pr and El irradiations caused carbonation of greases, and AO and UV irradiations induced oxidation of greases. Referred to the tribological properties of PI coated with PFPE oil, PI coated with PFPE greases showed minor changes in friction coefficient and wear rate, and the MoS₂ additives could significantly improve the lubrication properties of PFPE greases in simulated space environment.     

IPSW方法及其在变工况滚动轴承退化状态跟踪中的应用

感知获取的一维快变信号不仅受工况变化的影响,且无法避免地受到噪声干扰,此时传统的相空间曲变(PSW)方法提取的健康指数(HI)将无法胜任变工况下的滚动轴承退化趋势跟踪.针对这一问题,提出了改进的相空间曲变法(IPSW).从确保PSW分量的独立性及其信息最大化的角度出发,通过高维重构分量间的综合平均互信息局部极小化和互信...     

阀门零件表面二硫化钼涂覆工艺的研究

介绍了表面技术的分类及特点,阐述了阀门零部件二硫化钼涂覆技术的应用工艺。     

Influence of different friction conditions on the process of cold backward extrusion of steel

Backward extrusion of steel is a deformation process in which very high forces and tool pressures occur. Reduction of such high forces and tool pressures is possible by using an efficient lubricant. This paper describes an experimental investigation of the influence of different lubricants on the stress-strain state within the workpiece volume as well as on the stressing of the die. Best results were obtained when a phosphate-coated specimen was lubricated with MoS₂.