Friction reduction of water based lubricant with highly dispersed functional MoS2 nanosheets

Water based lubricant with superb features of low cost and good environmental compatibility, is considered to be a promising lubricating material. However, the poor lubrication properties of it greatly limit the practical application in a wide area. Two-dimensional MoS 2 nanosheets with special structural features and outstanding lubricating properties may be used as lubricant additives to enhance the tribological performance of water based lubricant. In this work, functional MoS 2 nanosheets modified with thiol molecules were obtained via a combined method of liquid exfoliation and thiol chemistry. The dispersion stability of the functional MoS 2 nanosheets in water were studied and the results showed that the nanosheets exfoliated by long sonication time could keep a stable dispersion over long periods of time. The results of tribological tests showed that the friction and antiwear properties of the water could be improved greatly with the addition of MoS 2 , and the water lubricant added with functional MoS 2 nanosheets had the best tribolgical properties. The low friction and improved antiwear of water could be attributed to the MoS 2 nanosheets which can be incessantly trapped between the contact junctions and then protect sliding surfaces. The enhanced tribological properties of the water lubricant with good dispersion stability of functional MoS 2 nanosheets may be useful for design of water lubricant with special surface characteristics of additives in the practical lubrication applications.