Improvers of pressure-viscosity coefficients of two-phase liquid-solid lubricants.

Abstract

The prediction of the pressure-viscosity coefficient, α, is one of the most important properties for Elastohydrodynamic lubrication (EHL) condition; thereby, the need for improvers to aid its measurement and performance is necessitated. This article presented two phase liquid – solid lubricants of PTFE and MoS2 solution in SAE 30 oil at varying compositions. The lubricants tested are SAE #30, SAE #30 plus PTFE and SAE #30 plus MoS2. High-pressure viscosity measurement was done at pressure up to 1.5 GPa and temperature range at 20°C to 100°C. Viscosity indices are calculated from the measured viscosity at 40 and 100 ºC using ASTM D 2270. However, an attempt to predict α for the blended lubricants using the relationship between pressure-viscosity coefficient and Walther’s logarithm of kinematic viscosity at atmospheric pressure was used. The pressure-viscosity coefficient of two phase liquid – solid lubricants were successfully predicted and the influence of solid lubricant concentration, and temperature on the lubricants viscosity were determined, and compared with SAE #30 oil. The properties and viscosity of mixtures obtained are optimal lubricant factors which optimze the measurement and performance of the highest EHL pressure-viscosity coefficient of the mixtures, and also enhance the better chance to improve the lubrication of machine element than the SAE #30 conventional engine oil.