Wear and friction of self-lubricating coatings applied to spur gears in fluid- free aerospace actuation gearboxes

Finch, Thomas, Vitu, Tomas and Polcar, Tomas (2024) Wear and friction of self-lubricating coatings applied to spur gears in fluid- free aerospace actuation gearboxes. Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 238 (1), 26-43. (doi:10.1177/13506501231197486).

Record type: Article

Abstract

Aerospace actuation gearboxes operate in low temperature environments where increased lubricant viscosity leads to significant no-load power losses. Replacing fluid lubricants with coatings applied to the gear teeth is one potential approach to improving gearbox efficiency. Here we develop an approach to determining average wear rates of coated gears using a power-recirculating test stand, profile measurements, and a model of the tooth contact. Worn gears are inspected using scanning electron imagery, and energy dispersive x-ray and Raman spectroscopy to understand the wear mechanisms and failure modes. Average coefficients of friction are determined at 20°C and -40°C using a power-absorbing test stand and isolation of tooth friction losses by calculation. These methods are then demonstrated on a promising C/Cr composite coating.

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e-pub ahead of print date: 6 October 2023

Published date: January 2024

Additional Information: Funding Information: The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Ministerstvo Školství, Mládeže a Tělovýchovy (grant number CZ.02.1.01/0.0/0.016 026/0008396). Funding Information: The authors would like to thank Teer Coatings for performing the coating deposition and Collins Aerospace for funding the manufacture of the test rigs and samples. Funding Information: The authors would like to thank Teer Coatings for performing the coating deposition and Collins Aerospace for funding the manufacture of the test rigs and samples. The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Ministerstvo Školství, Mládeže a Tělovýchovy (grant number CZ.02.1.01/0.0/0.016 026/0008396). Publisher Copyright: © IMechE 2023.

Keywords: Dry friction, Dry wear, Self-lubricating coating, Spur gear, coatings, efficiency, Gears, dry sliding wear, dry friction