MWCNTs filled high-density polyethylene composites to improve tribological performance

Abstract

The water-lubricated stern tube bearings play a considerable role in the marine propulsion system. Due to poor mechanical properties and temperature resistance, polymer materials are prone to plastic deformation during friction under extreme conditions, which could induce frictional vibrations and noise. Reducing the coefficients of friction (COFs) and weakening the plastic deformation of the contact surface could significantly decrease its frictional vibrations and noise. A novel composite material composed of high-density polyethylene (HDPE) and multi-walled carbon nanotubes (MWCNTs) was prepared to investigate its tribological properties, which slid against ceramic balls under low velocity and heavy load. The influence of MWCNTs on wear behaviours was examined by comparing and analyzing the mechanical properties, scratch testing results, coefficients of friction (COFs), wear volumes, and wear morphologies. The results indicated that MWCNTs obviously enhanced the mechanical properties of HDPE and weakened the deformation behaviours on the friction interface, which resulted in reductions of COFs and wear volumes under dry and water-lubricated conditions. HDPE modified by 7.5 wt% MWCNTs presented the best COF reduction and wear resistance improvement, and the effect mechanism of the MWCNTs was revealed. The knowledge obtained in this research would be useful to develop polymer matrix composites with low COFs, and good deformation resistance and enhance the tribological properties and frictional vibration reduction ability of water-lubricated polymer bearings.