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Abstract

Several research projects have been completed as part of an ongoing programme of work into solid-lubricated bearings for high-temperature space operation.

Testing of bearings indicated that MoS₂ lubrication is effective at high temperature, but highlighted a potential problem with the commonly used material PGM-HT – that it can shrink permanently during initial heating, leading to loss of clearances and high torques. This effect was subsequently measured quantitatively – components have been shown to contract by ∼ 1.5 per cent on heating to 250 °C. A thermal conditioning regime was devised to avoid the problems of shrinkage.

A number of alternatives to conventional cages were also designed, manufactured, and tested. Hybrid cages, with a metal body and inserts made of self-lubricating materials – PGM-HT and SINTIMID 15M-HT, were identified to be an effective option, which avoids problems with conventional cage designs. Toroidal ball separators made of three different self-lubricating materials – PGM-HT, PTFE, and Vespel SP3 – were also designed, manufactured, and tested.

Keywords

tribology space tribology self-lubrication molybdenum disulfide lead high temperature ball bearings lubrication solid lubricant vacuum

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