The Secondary Lubrication Effect under Fluid Lubrication

Surface texturing under fluid lubrication has been effectively used to improve the tribological performance. However research on the ‘secondary lubrication effect’ in the later stage of fluid lubrication is scarce. This study aimed to examine the friction reduction mechanism of the ‘secondary lubrication effect’ under fluid lubrication and to investigate factors that affect the effect. Lubrication models were developed under fluid lubrication. Friction force and hydrodynamic pressure of the lubricant were analyzed. Furthermore, the texture's oil-storage and -release capacities which may affect the ‘secondary lubrication effect’ were studied respectively. The results showed that the ‘secondary lubrication effect’ reduced friction by generating hydrodynamic pressure. The friction force in the later stage was higher than that in the early stage of fluid lubrication. The decrease in friction caused by the ‘secondary lubrication effect’ decreases in proportion with the loss of the lubricant. The lubricant infiltration capacity will affect the ‘secondary lubrication effect’ by influencing the texture's oil-storage capacity. Additionally, the release mechanism of the lubricant inside the texture was also obtained. Texture depth had a significant effect on the‘secondary lubrication effect’ by affecting the texture's oil-release capacity.