Synthesis and tribological properties of MoS 2 composite nanoparticles with different morphologies

Abstract

Molybdenum disulphide composite particles made of both hollow nanospheres and nanoplatelets were synthesised in a single process using a chemical method that was optimised by adjusting the relative proportions of Na₂S and thioacetamide (TAA) precursors. The composite nanoparticles were characterised using powder X-ray diffraction, transmission electron microscopy and thermal analysis; four-ball tribological tests were used to assess their lubricating effect when used as additives in liquid paraffin dispersions. The results showed that composite nanoparticles of appropriate shape distribution could only be synthesised with a high dosage of TAA: too high concentrations of Na₂S were shown to destroy the template chain of TAA and disturbed the formation of nanospheres. The MoS₂ composite particles exhibited a better lubricating effect as compared to composite particles produced by mechanical mixing of separately produced nanospheres and nanoplatelets, confirming that the chemical method can lead to a better synergistic lubrication between two kinds of MoS₂ nanoparticles.