Tribological behavior of high-density polyethylene in dry sliding contact with ion-implanted CoCrMo

The surface of a CoCrMo alloy has been modified using beamline ion implanta tion of boron, carbon and nitrogen, and diamond-like carbon (DLC) depositio n. All surface treatments, with the exception of high-dose nitrogen-ion imp lantation, result in an increase in surface hardness. However, wear and fri ction either remain similar to, or become worse than, those of the unimplan ted alloy. Experiments show that adhesion energy and energy of deformation are the two major components influencing the frictional behavior of the CoC rMo-high-density polyethylene (HDPE) wear system. Wear was dominated by mat erial loss in the HDPE pin. No correlation between wear and CoCrMo hardness was observed, indicating that adhesion or plowing in HDPE pins is not corr elated with the mechanical properties of the counterface materials. A compa rison of the ion-implanted samples with DLC-coated CoCrMo showed the KDPE-D LC sliding system to have the largest coefficient of friction. The friction behavior of this system was found to be controlled by an adhesive build-up of HDPE on the DLC surface. (C) 1999 Elsevier Science S.A. All rights rese rved.