Lubrication performance of multialkylatedcyclopentane oils for sliding friction of steel under vacuum condition

Abstract Sliding friction experiments under vacuum lubricated with additive‐free multialkylatedcyclopentane (MAC) were carried out using a ball‐on‐disc tribometer with 440C stainless steel as the material of the specimen. Antiwear characteristics of additive‐free MAC during the steady friction region under vacuum were shown to be better than those of perfluoropolyether (PFPE). However, it was found that the friction coefficient lubricated with the additive‐free MAC under vacuum showed an initial seizure‐like high friction of approximately 0.2 at the beginning of the test, followed by a steady low friction of approximately 0.1. It was also found in contrast that PFPE did not show the initial seizure‐like high friction but maintained a lower friction coefficient than 0.1 throughout the experiment. The initial high wear volume lubricated with the additive‐free MAC was found to be related to the initial seizure‐like high friction. The tricresylphosphate formulation prevented the initial seizure‐like high friction. Copyright © 2007 John Wiley & Sons, Ltd.