On the size effect of molybdenum disulfide particles on tribological performance

Abstract

Purpose

To provide a suitable useful mixing ration of nano‐sized molybdenum disulfide and commercial common molybdenum sulfide (MoS₂) particles (approximately 1.5 μm in diameter) in liquid paraffin, which can lead to a better tribological performance.

Design/methodology/approach

The MoS₂ nanoparticles and commercial common MoS₂ particles (approximately 1.5 μm in diameter) were dispersed in liquid paraffin with different concentrations and ratios by means of ultrasonic in order to study their lubrication capacity, friction reduction and wear resistance. The tribological experiments were carried out by MQ‐800 four‐ball tribometer, in which extreme pressure, wear scan diameter and friction coefficient were measured. It was analyzed that the chemical status of elements on the rubbed surface by X‐ray photoelectron spectroscopy (XPS), and it was observed that the surface topography of wear scan by scanning electron microscope (SEM).

Findings

The results showed that the loading capacity of liquid paraffin with different kinds of MoS₂ particles were increased with their contents. The liquid paraffin containing the mixture of MoS₂ nanoparticles and common MoS₂ particles has a better wear resistance, friction‐reducing performance and extreme pressure property than the liquid paraffin containing pure common MoS₂ or pure nano‐MoS₂ particles. The optimal mixing ratio of nano‐MoS₂ and common MoS₂ is 20 wt percent, the loading capacity reaches the highest value. By XPS and SEM it was suggested that the difference in the tribological performance between MoS₂ nanoparticles and MoS₂ common particles was attributed to the surface and interfacial size‐effect of nanoparticles and the formation of molybdenum trioxide thin film on the rubbed surface.

Research limitations/implications

It is not studied that the effects of mixing of common MoS₂ and nano‐MoS₂ in the actual lubricating oil with various additives.

Practical implications

It provided a basic research results and data for the application of nano‐MoS₂ particles.

Originality/value

The mixing of nanoparticles and non‐nano‐sized particles will lead to new tribological results, which is different from results obtained from other nanoparticles before.

Citation

Hu, X. (2005), "On the size effect of molybdenum disulfide particles on tribological performance", Industrial Lubrication and Tribology, Vol. 57 No. 6, pp. 255-259. https://doi.org/10.1108/00368790510622353