Insights into the effect of thermocapillary migration of droplet on lubrication

Abstract

Thermocapillary migration, as a liquid lubricant loss mechanism, will lead to the failures of moving mechanical assemblies due to lack of lubricant. The purpose of this study was to determine the influence of thermocapillary migration of droplet on surface lubrication properties. An experimental set-up was designed to investigate the migration behavior of paraffin oil driven by temperature gradient. Friction tests were carried out to evaluate the influences of lubricant migration on tribological performance. Aspects of the temperature gradient, oil volume and initial migrating time were taken into account. The experimental results showed that the increment of temperature gradient and oil drop volume can both enhance the average velocity of drop migration, while the average velocity decreases over time. Temperature gradient exhibits the dominated effect on surface lubrication properties and starvation first takes place at the highest temperature gradient. In addition, a transition of wear mechanism from an abrasive to adhesion wear is observed in particular situations.