Synthesis of nanostructured flower-like MoS2 and its friction properties as additive in lubricating oils

Purpose This paper aims to synthesize nanostructured flower-like molybdenum disulphide (MoS2) particles and evaluate their suitability to act as additives for lubricants. Design/methodology/approach A hydrothermal method without any surfactant successfully produced 250 nm mean diameter Nanostructured flower-like MoS2 particles. The resulting product was then solvothermally treated with absolute ethanol producing lipophilic powder particles which after being dispersed in two different lubricants were tribologicaly characterized by using a pin-on-disk tribometer geometry with reciprocal movement under immersion. Findings The influence on the stability and the coefficient of friction of the nano-oils is shown to be strongly dependent on their molecular structure. After 1 h of tribological testing, a ramified polyolester oil with 1 Wt.% of MoS2 nanoflowers did not show decrease in its average coefficient of friction, while an additive naphthenic oil with the same concentration of nanoparticles showed a decrease of 86 per cent. Originality/value In this paper, nanostructured flower-like MoS2 synthesized by the hydrothermal method was dispersed in lubricating oils to study its stability and tribological properties. To ensure good stability of the nano-oils, the particles were solvothermally treated with absolute ethanol to dehydrate and lipophilize them. A ramified polyolester-based nano-oil with 1 Wt.% of MoS2 nanoflowers showed no decrease in its steady state coefficient of friction, while a naphthenic-based nano-oil with the same concentration of nanoparticles presented a remarkable 86 per cent reduction.