MoS2 dry lubricated contacts exposed to space environments

对空间机构进行润滑是非常具有挑战性的，因为必须在多种环境下、在较宽的温度范围内保持润滑，同时在整个机构寿命期间(进入空间长达15年)避免任何污染航天器机载设备的风险，特别是光学设备。在过去的60年里，摩擦学研究表明，物理化学和力学之间存在耦合，影响润滑剂的摩擦学行为和效率。尽管如此，仍然缺乏信息来制定有效的干式润滑预测模型。 自1941年以来，推荐用于真空使用，空间应用中最常用的干式润滑剂是二硫化钼MoS2。然而，对MoS_2的真实润滑机理的预测还很欠缺。最近，在为詹姆斯·韦伯太空望远镜设计的一些设备的开发过程中，仍然遇到了MoS2的润滑问题，这是COM DEV International非常感兴趣的问题。前人对MoS_2的研究对MoS_2在不同条件下提供良好或不良润滑的原因给出了深刻的见解和完整的定性解释。低摩擦的关键在于一层薄层的流变性，这种薄层被称为第三体，在运动部件和 其特征取决于环境。 该项目旨在开发实验工具来测量第三物体的机械性能，以表征其流变性，并为并行开发的数值模型提供信息。该项目将启动COM DEV国际公司和多伦多大学纳米机械和材料实验室(NanoM2)之间的合作。最终，该项目的目标是开发一种通用模型，可以用于不同类型的空间应用材料。

Lubricating space mechanism is very challenging as lubrication must be sustained in several environments, over a wide temperature range while avoiding any risk of contamination of the spacecraft on-board equipment, especially optics, all along the mechanism life (up to 15 years once in space). Throughout the last 60 years, tribological studies have shown that coupling exists between physicochemistry and mechanics, influencing the tribological behaviour and efficiency of lubricants. Nonetheless, information is still lacking in order to formulate efficient predictive models of dry lubrication. Recommended for vacuum use since 1941, the mostly used dry lubricant for space application is the molybdenum disulphide MoS2. However, prediction of the MoS2 lubrication in real mechanism is still lacking. Recently, lubrication issues with MoS2 have still been encountered in the development of some equipment intended for the James Webb Space Telescope, which is a problem of great interest for COM DEV International. A former study on MoS2 gave strong insights and a complete qualitative explanation on the reason for the good or bad lubrication provided by MoS2 under different conditions. The key for low friction relies on the rheological properties of a thin layer, called the 3rd body, created between both moving parts and whose characteristics depends on the environment. The project aims to develop experimental tools to measure the mechanical properties of the 3rd body to characterize its rheology and inform a numerical model developed in parallel. The project will initiate a collaboration between COM DEV International and the NanoMechanics and Materials Laboratory (NanoM2), University of Toronto. Ultimately the project aims to develop a general model that can be used with different kind of materials for space applications.