A tracer method to determine extremely low wear rates of ultrahigh molecular weight polyethylene

Wear testing protocols of ultrahigh molecular weight polyethylene (UHMWPE), which rely on gravimetric or topographic measurements, or both, for wear determination, are usually complicated due to fluid absorption or creep, or both, of the polyethylene samples. In this study we report the feasibility of using a tracer material to quantify wear of polyethylene. Europium (Eu), a rare earth element, has been identified as a suitable tracer material. Eu can be quantified with ICP-MS. Nascent UHMWPE powder has been mixed with a solution of Eu-acetate. Different mixing techniques were tried to homogenize the tracer distribution before consolidation. After molding, the 10-mm diameter pins were worn on a pin-on-disk testing apparatus. In addition, lubricant samples were taken at regular time intervals. The Eu content was analyzed and the derived polyethylene wear rate was compared with the weight loss of the pins.