A rheological and tribological study has been performed for six available lubricants for space applications. PFPE oil PTFE-thickened greases have shown interesting properties. Among these Krytox 240AD appears too viscous for space applications even if its thickener size and nature seem compatible with space lubricaton requirements. On the other hand, much too large particles have been found in both Braycote greases. Braycote 608 behaves like a semi-fluid lubricant and displays good performance during tribological experiments. This first part leads to the realisation of thirteen experimental PTFE and MoS2 thickened greases. This second part aims at a better understanding of the influence of each component in the lubricant behaviour. Some rheological results have been presented here, the thickener and base oil influence has been pointed out. These steady-state measurements will be completed by dynamic rheological characterisations. The elastic parameters will be determined following the Doraiswamy's analysis which has been successfully applied to the existing suspensions. As this work initiates a more general study dealing with the contact replenishment under space conditions, complementary actions have been conducted. Thermocapillary migration experiments have been performed for the base oils and the LMC lubricants. Future tribological simulations for the most interesting lubricants should allow to validate the first conclusions in the lubricant behaviour optimisation, from the replenishment point of view.
Optimisation of rheological behaviour of thickened liquid lubricants for spacecraft applications
Optimierung des rheologischen Verhaltens verdickter flüssiger Schmiermittel für Raumfahrt-Anwendungen
1995
10 Seiten, 9 Bilder, 3 Tabellen, 13 Quellen
Conference paper
English
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