Tribological behaviors of carbon fibers (CF) reinforced poly-ether-ether-ketone (PEEK) composites are investigated at low speeds ranging from 0.01 to 0.2 m/s under pressures varying from 1 to 30 MPa. Nano-Bi₂O₃, nano-SiO₂ and conventional solid lubricants (graphite and polytetrafluoroethylene) are further added into CFreinforced PEEK, respectively. It is demonstrated that a small load and relatively high speed are favorable for the wear-reduction role of nano-Bi₂O₃, while the positive role of nano-SiO₂ is pronounced at a high load and speed. Friction and wear-reduction roles of the solid lubricants are the most significant at low load and low speed. It turns out that functionalities of the fillers are closely associated with their roles in tribofilm growth
governed by complex physical and chemical actions.