| Wear was the primary cause of failure of joint replacement. In this study, in consideration of surface properties and environmental elements, two-step plasma immersion ion implantation technique, thermal oxidation (TO) treatment, laser surface texturing (LST) treatment and LST-TO treatment were developed and applied for modification of Ti6A14V alloy. The surface structure, composition, contact angle and microhardness of the modified alloys were measured. The friction and wear properties of ultra high molecular weight polyethylene (UHMWPE) sliding against the modified alloys under different lubrications were investigated using a pin-on-disc tribometer.After the two-step plasma immersion ion implantation, a graded titanium oxide-titanium nitride film was formed in the subsurface of Ti6A14V alloys, the wettability and the microhardness of the modified alloy surfaces were increased significantly. Under serum lubrication, the friction coefficient decreased by 3.3% and the wear resistance of UHMWPE increased by about 23 times against the ion implanted Ti6A14V alloy. Many deep furrows were found on the surface of the un-implanted alloy and were absent on the ion implanted surfaces of the alloy. After TO treatment, the wettability and the microhardness were increased significantly. The thickness and the oxygen concentration of the oxidizing film were increased as the oxidizing temperature rising. The oxidizing film began to scale off at 850℃. Under serum lubrication, the friction coefficient decreased by 63% and the wear resistance of UHMWPE increased by about 16 times against the alloy which was oxidized at 600℃ for 120min. The wear mechanism of TO-treated alloy was slightly abrasion. After LST treatment, the micropores on the surface of alloy would act as reservoirs for lubricants and wear particle traps. Under serum lubrication, the friction coefficient decreased by 52% and the wear resistance of UHMWPE increased by about 13 times against the textured alloy. The wear mechanism of tortured alloy and UHMWPE counterface were abrasion, fatigue wear cooperated with abrasion respectively. After LST-TO treatment, by virtue of both TO treatment and LST treatment, the friction coefficient decreased by 76% and the wear resistance of UHMWPE increased by about 17 times against the modified alloy under serum lubrication. There were almost no notable wear features on the modified surface of the alloy, and the wear mechanism of UHMWPE counterface changed from abrasion to fatigue wear. |
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