Gears manufactured from titanium alloy offer several potential advantages for spacecraft applications, if their propensity to adhesive wear (galling) can be inhibited. This paper reports on an experimental investigation into the performance of a range of surface treatments on the alloy IMI 318 (Ti-6Al-4V). The gears were tested unlubricated in vacuum, using a 'four square' rig. Gear performance was determined by life or number of tooth encounters before failure of the surface treatment rather than by wear depth. Conventional treatments such as nitriding or oxidation have been found to offer limited improved gear life, above that of the untreated alloy. Boronising gave the longest gear life but caused, during treatment, some dimensional growth of the gears. Sputter-deposited coatings of titanium nitride (TiN) were poorly adherent to the substrate and had short lives. Arc-evaporated coatings of TiN gave improved performance until coating fracture and subsequent galling of the titanium alloy occurred.
Surface-treated titanium alloy gears for space mechanisms
Getriebe aus oberflaechenbehandelter Titanlegierung fuer Raumfahrtmechanismen
Second European Space Mechanisms and Tribology Symp. European Space Agency (ESA), Meersburg ; SP-231 , Okt ; 167-171
1985
5 Seiten, 6 Bilder, 2 Tabellen, 10 Quellen
Conference paper
English
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