Ultrahigh molecular weight polyethylene (UHMWPE) was
implanted with O~+ and C~+ ions at different energies and doses. The
friction and wear behaviors of the ion implanted UHMWPE sliding against Si_3N_4 under the lubrication of plasma were investigated on a pin-on-disk test rig. The morphologies of the original surface and wear scar of the un-implanted and implanted UHMWPE
specimens were observed on a scanning electron microscope, while the chemical features of the un-implanted and implanted UHMWPE specimens were examined by means of reflection infrared spectrmetry. It was found that O~+ and C~+ ion-
implantation contributed to increasing the wear resistance of UHMWPE, which was related to the ion-implantation-induced surface carbonization and the formation of a diamond-like structure therewith. Moreover, O~+ implanted UHMWPE specimen showed better wear resistance than the C~+ implanted one, and the UHMWPE specimen implanted with O~+ at an energy of 450 kV and dose of 5×10~(15)/cm~2 had the smallest wear rate. The un-implanted UHMWPE was characterized by adhesion, plowing, and plastic deformation as it slid against the ceramic ball under the lubrication of plasma; while the ion-implanted UHMWPE was dominated by fatigue and abrasive wear under the same testing conditions.