In-situ fabrication of a UHMWPE nanocomposite reinforced by SiO2 nanospheres and its tribological performance

Highlights: • An in-situ fabrication method of nanocomposites is disclosed. • The silica nanospheres were in situ filled into UHMWPE in liquid phase. • The filled silica nanospheres were well dispersed and combined with UHMWPE. • The COF against 45^# steel and wear rate in sand slurry were markedly reduced. • The content of aqueous ammonia and the loading of nanofillers were key points. -- Abstract: In-situ fabrication of nanocomposites facilitates the dispersion of nanofillers in organic matrixes by decreasing the agglomeration of nanofillers compared to a mechanical mixing method. UHMWPE nanocomposites filled SiO₂ nanospheres (SNS) were in-situ fabricated by a sol-gel method in this work. Their sliding coefficient of friction and wear rate were determined by a high-speed ring-block wear test apparatus against 45^# steel under dry friction conditions, and the tribological behaviors at elevated temperature were tested by a slurry abrasion wear configuration. The in-situ filled SiO₂ nanospheres presented an excellent dispersion on UHMWPE, and the fabricated SNS/UHMWPE nanocomposites were found a remarkable enhancement in stiffness, glass transition temperature and hydrophobicity. Furthermore, the SNS/UHMWPE nanocomposites exhibited markedly improved tribological performances than the matrix UHMWPE and the referenced sample prepared by a mechanical mixing method: the sliding coefficient of friction was reduced by over 50% than that of the pristine UHMWPE against a 45^# steel ring under dry friction, and the mass wear rate was ca. 59% of the UHMWPE matrix determined by a water-bath mortar at an elevated temperature.