A Fundamental Study on the Development of Lubrication Performance in Space Mechanisms under the Model Atmosphere on the Mars Surface

火星探测的空间机制受到高真空、低温、二氧化碳气氛等多种条件的影响。为了研究包括液体润滑剂在内的各种润滑剂在火星表面大气环境下的润滑性能，研制了一台新型真空摩擦试验机。利用液态N_2捕获器获得了10^&lt；-7&gt；Pa真空度。残渣气体可以用质谱仪进行分析。通过在底板中循环液氮，可以将低摩擦试件支架冷却到-100℃左右。在这项工作中，使用了4种商用空间液体润滑剂，包括3种全氟乙烷(B型、D型和FZ型)和1种合成烃(多烷基环戊烷)。在真空条件下，所有润滑剂在室温下都表现出类似的良好润滑性能，但在摩擦过程中温度逐渐降低时，在一定的低温下，所有润滑剂都表现出突然的摩擦增加。观察到摩擦力突然增加的温度顺序如下。FPE-B&GT；PFPE-F&GT；PFPE-D&GT；MACMAC在-70℃左右保持着低而稳定的摩擦力，但MACMAC润滑的摩擦表面比PFPE润滑的表面粗糙且损伤严重。

Space mechanisms for mars investigation suffer from several conditions, such as high vacuum, low temperature, carbon dioxide atmosphere, and so on. A new vacuum tribometer was developed to investigate the lubrication performance of various lubricants including liquid lubricants considering the atmosphere on the mars surface. A vacuum of 10^<-7> Pa was attained using liquid N_2 trap. Residua gas could be analyzed using mass spectrometer. The lower friction specimen holder could be cooled down to around -100℃ by circulating liquid nitrogen in the base plate.In this work, commercially available 4 liquid lubricants for space applications, including 3 PFPEs (Type B, Type D and Type FZ) and 1 synthetic hydrocarbon (Malti-alkylated cyclopentan) were used. All the lubricants showed similar good lubricating performance under the room temperature in vacuum but when the temperature was gradually decreased during friction, all the lubricants showed sudden friction increase at the certain low temperatures. The order of the temperature where the sudden friction increase was observed is as follows. PFPE-B>PFPE-F>PFPE-D>MAC MAC maintain low and stable friction down to around - 70℃, but the friction surface lubricated with MAC was rougher and was much damaged compare to those lubricated with PFPEs.