Characterization of biodiesel and soot contamination on four-ball wear mechanisms using electron microscopy and confocal laser scanning microscopy

Abstract

Utilization of biodiesel as an alternative fuel has been increasing nowadays in term of quantity and ratio of bio-resource derived esters from B7 to B100. The tribological characteristic due to biodiesel application has been more interesting. Not only fuel dilution but also soot contamination in engine oil must be taken into account for the effect to the engine wear. This research employed carbon black as soot model and B7, B20 and B100 as contaminated fuel. Two blended grades of diesel engine oils (API CI-4 and CK4) were tested by a four-ball wear tester. Scanning electron microscopy (SEM) was used to investigate the wear characteristic. Three-dimensional images of wear scars and surface roughness were observed from confocal microscopy technique. The result shows that CK-4 has greater anti-wear performance and can maintain the lubricating performance when the oil is contaminated. For CI-4 cases, soot contamination causes increasing wear, but biodiesel fuel dilution shows wear reduction.