Tribological properties of palm oil blended with zinc dioctyldithiophosphate

Abstract

This paper analyses the tribological properties of commercialised palm base oil blended with zinc dioctyldithophospate (ZnDoDP) as a substitute for mineral-based oil, which, despite its known drawbacks, is commonly used in the lubricant industry (automatic transmission fluid). Palm oil was mixed with ZnDoDP as an additive at a range of concentrations from 0 to 3.0 wt%. The samples were mixed using an ultrasonic homogeniser. Then, the samples were tested to determine their lubricant properties via elemental analysis as per ASTM D6595, viscosity index (VI) as per ASTM D2270, and total acid number (TAN) as per ASTM D664. A tribological test was then performed using a four-ball tester as per ASTM D4172, with the worn surfaces of the balls imaged using Scanning Electron Microscopy (SEM) and Energy-dispersive x-ray Spectroscopy (EDX). The results found that 2.0 wt% of ZnDoDP shows excellent characteristics in terms of its lubricant properties, coefficient of friction, and wear. However, ZnDoDP mixed with palm oil reported a higher acid number due to the acidic characteristic of the additive itself.