Experimental Investigations to Study the Effect on Coefficient of Friction and Heat Transfer Coefficient in the Lubricants With Nano Blending

Abstract

Worm gears are unique in their ability to achieve large speed reductions in a compact space with gear ratios of 20:1, 60:1 and 200:1 or even higher in some cases and have transmission efficiency between 50% and 70%. One of the major drawback in worm drive design is the relative motion between the two mating elements is entirely sliding. This sliding motion continuously expels the lubricant aside leading to higher wear and increase in temperature. This phenomenon leads to high wear and higher temperatures, which are the limiting factors in the worm drives. Nano particles have gained a greater attention in the recent years because of their highly enhanced thermal and tribological properties when blended with conventional lubricants. In the present investigations the addition of Al2O3 nano particles with average particle size of 30 nm in SAE 140 gear oil resulted in reducing the coefficient of friction, wear and enhanced the heat transfer coefficient. It is observed that coefficient of friction is decreased by 8.98%, 10.11% and 16.85% at nano particle volume concentration of 0.1%, 0.2% and 0.5% respectively at room temperature. Frictional force was found reduced by 26.02% at room temperature for 0.5% volume concentration. Further it was also noted 32.25% and 18.55% reduction in frictional force at the temperatures 60°C and 90°C respectively for 0.2% volume concentration. Convective heat transfer coefficient is increased with increasing particle volume concentration and maximum enhancement of 46.35% in heat transfer coefficient observed at 0.5% volume fraction. The results depict that lubricants blended with nano particles exhibit enhanced tribological and heat transfer properties.