Performance Limits of Surface-Hardened Aluminum-Alloy Gears in Vacuum

摘要

The surfaces of aluminum alloy gears operating in vacuum were treated by Ematal anodizing and the Zinal diffusion process. Without lubrication, both surface treatments fail quickly by cracking of the brittle coatings and subsequent flaking. Treated aluminum gears are not, therefore, recommended for spacecraft applications which demand more than a few thousand tooth encounters. Lubrication with sputter-deposited MoS2 increases the endurance of the Ematal coating by a factor of 15, to 2 million gear revolutions. Coupling an Ematal-treated gear with a self lubricating polyimide/MoS2 gear extends the life further, with no failure after 10 million gear revolutions.