Investigation of running-in process in water-based lubrication aimed at achieving super-low friction

• Published in: Tribology international Vol. 102; pp. 257 - 264
• Main Authors: Deng, Mingming, Li, Jinjin, Zhang, Chenhui, Ren, Jing, Zhou, Ningning, Luo, Jianbin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2016
• Subjects: Liquid surperlubricity; Running-in; Silica layer; Wear; Liquid surperlubricity; Silica layer; Running-in; Wear
• ISSN: 0301-679X; 1879-2464
• DOI: 10.1016/j.triboint.2016.05.023

In this work, effects of running-in process on achieving super-low friction between silicon nitride ball and sapphire disc under lubrication of mixtures of sulfuric acid and glycerin, was investigated. The results revealed that sulfuric acid plays the key role in the running-in process. Owing to this acid, a smooth worn region was generated on the silicon nitride ball through chemical-mechanical abrasion, which provided favorable conditions for super-low friction under elastohydrodynamic lubrication. Meantime, a silica layer formed on part of the worn region through tribochemical reaction during running-in process, contributing to the realization of super-low friction under boundary and mixed lubrication. Moreover, the adsorption of hydrogen ions on friction surfaces generated a repulsive double-layer force that also contributed to super-low friction. [Display omitted] •Surface composition and structure due to running-in process favor super-low friction.•Running-in provides condition for elastohydrodynamic lubrication to reduce friction.•Silica layer formed in running-in process provides excellent boundary lubrication.•Hydrogen ions adsorbed on the friction surfaces contribute to super-low friction.