The Lifetime of Boundary Lubrication Performance of Small-Quantity-Applied Liquid Lubricants for Space Mechanisms Evaluated with a Vacuum Reciprocating Tribometer
A small quantity of additive-free multiply alkylated cyclopentanewas applied to the specimen to evaluate theboundary lubrication performance and its lifetime under highvacuum condition. A ball-on-disk type vacuum reciprocatingtribometer was used to measure the friction coefficient and theseparation voltage during the tribotest operated under high vacuum.The thickness of the liquid lubricants on the specimen wasaltered from less than 1 μm to 165 μm. The lubrication lifetimeof the additive-free MAC increased with the lubricant thickness.At the initial duration of the test, the friction coefficientat both edges and a center position of the reciprocating motionwas stable and low. After a certain sliding distance it wasobserved that the separation voltages became zero, the frictioncoefficient gradually increased with testing time, and finally aseizure-like high friction occurred. Generally, the friction coefficientat the edge of the stroke was larger than that at the center.In contrast, when the film thickness was large and the lubricationlifetime became long, the friction coefficient value at theedge and the center inverted after a certain sliding distance, andfinally the authors observed a seizure-like high friction. Thefriction coefficient inversion was possibly due to the insufficientsupply of the lubricant from the surrounding due to the viscosityincrease. The occurrence of oxidative polymerization underhigh vacuum catalyzed by a nascent surface was suggested.
各種検索
サポート
ヘルプ