O1264 THE USE OF CARBON ION IMPLANTATION TO MODIFY THE FRICTIONAL BEHAVIOUR OF PRESENT-DAY BIOMATERIALS

Abstract

Aims: Stribeck analyses were performed using both unimplanted and carbon (C) implanted heads of alumina, zirconia, zirconia-toughened-alumina and stainless steel so as to study the influence of C implantation on the frictional behaviour of these orthopaedic bearing materials. Methods: The selected biomaterials were implanted using an ion dose of 1 and 2.5 x 10¹⁷ C ions/cm² (75 keV). Friction testing was carried out on unimplanted and C implanted heads using a Hip Joint Friction Simulator with aqueous solutions of carboxy-methyl cellulose (CMC). Results: Both the unimplanted and C implanted bearing couples displayed a similar trend, i.e. by increasing the viscosity of the CMC fluid, the friction factor was found to decrease due to the formation of a fluid film between both bearing surfaces. However, the friction factor for the treated couples at low viscosities was lower than that of their unimplanted counterparts, with a drop of approximately 10% for the steel-on- UHMWPE and a drop of up to 85% being observed in the friction between the ceramic-on-ceramic bearing couples. This decrease can be explained by ion beam smoothening of the treated surface. Conclusions: The results from this study indicate a beneficial reduction in the friction factor of the C ion implanted surfaces. These results indicate that the use of C ion implantation to modify the bearing surfaces of present-day orthopaedic implants may be an effective means of reducing detrimental wear debris at the bearing interface.