Improved wear resistance of ultra-high molecular weight polyethylene by plasma immersion ion implantation

Surface modification of ultra-high molecular weight polyethylene (UHMWPE) has been explored using the novel non-line-of-slight plasma immersion ion implantation (PIII) with nitrogen. The modified surfaces were characterised by SEM and a Nano Test 600 testing machine. The tribological behaviour of PIII treated UHMWPE sliding against AISI 316L stainless steel counterfaces was evaluated using a pin-on-disc tribometer under water lubricated conditions. The experimental results show that PIII is a very promising surface engineering technique to improve such surface mechanical properties as surface hardness and elastic modulus of UHMWPE. As a result, the wear resistance of UHMWPE was significantly enhanced by a factor of three following PIII treatment, as compared with untreated material. It was found that the significantly improved wear resistance of PIII treated UHMWPE can be mainly attributed to ion bombardment induced cross-linking, and thus surface hardening.