In the present experiments, friction coefficient and wear of polyester composites reinforced by nanoparticles of iron, copper, aluminum, and aluminum oxide and dry sliding against steel were investigated to develop new engineering materials with low friction coefficient and high wear resistance which can be used as bearing materials. Experiments were carried out at dry sliding. Cylindrical test specimens of 10 mm diameter and 30 mm length of polyester resin filled by nanoparticles were tested. Pin on disc tribometer was used to perform friction and wear experiments under the application of electric direct current of 0, ± 1.5, ± 3 and ± 4.5 volts. Experiments showed that, when the test specimenswere negative charged, friction coefficient increased with increasing electric voltage for composites filled by aluminium, while at no voltage, friction coefficient decreased with increasing aluminium content. As the electric voltage increased wear decreased. The lowest wear values were displayed by polyester filled by 6 – 10 wt. % aluminium content. Polyester composites filled by copper displayed relatively lower friction than that observed for composites filled by aluminium. In condition of applying electric voltage friction coefficient increased with increasing copper content. As for positive charged test specimens, application of electric voltage showed significant wear decrease. Wear resistance when applying negative voltage was better than that observed for positive voltage. Besides, friction coefficient showed relatively higher values than that observed for composites of negative voltage. Wear showed the same trend observed for composites of negative voltage. Composites filled by 10 wt. % copper at 4.5 volt showed the lowest wear value.
Magda et al. (Sun,) studied this question.