Effects of carbon soot from the combustion of diesel fuels on the tribological properties of lubricating oil and diesel fuels

Abstract

Purpose

This paper aims to explore the effects of mineral diesel fuel carbon soot (MCS) and biodiesel carbon soot (BCS) on the lubrication of polyalphaolefin (PAO) and diesel fuels.

Design/methodology/approach

Two styles of carbon soot were prepared from the natural combustion of mineral diesel fuel oil (MDO) and biodiesel oil (BDO). Tribological tests were conducted on a high-frequency reciprocating rig. Friction surfaces were characterized using three-dimensional laser scanning confocal microscopy and Raman spectroscopy.

Findings

The addition of MCS and BCS to PAO could reduce friction in most cases. MCS had a negligible effect on the wear for contents not exceeding 1.0 per cent. By contrast, BCS exhibited a considerable negative influence on the wear resistance even at low contents. For diesel fuels, MCS reduced both friction and wear, whereas BCS substantially deteriorated the lubrication of BDO. MCS formed a Fe₃O₄/C composite lubricating film on the friction surface. BCS also entered the contact region, but it did not form an effective Fe₃O₄/C composite lubricating film.

Originality/value

This work compared MDO and BDO from a different perspective, i.e. the effects of their combustion carbon soot on the lubrication of lubricating oil and fuel oil. The significant negative effect of BCS on the lubrication of lubricating oil and BDO is a problem that could occur in the industrial application of BDO.

Citation

Shi, B., Guo, J.H., Cao, X.A., Hu, E.Z. and Hu, K.H. (2018), "Effects of carbon soot from the combustion of diesel fuels on the tribological properties of lubricating oil and diesel fuels", Industrial Lubrication and Tribology, Vol. 70 No. 3, pp. 532-537. https://doi.org/10.1108/ILT-09-2016-0197