ADHERENCE OF DIAMOND-LIKE CARBON COATINGS ON TOTAL JOINT SUBSTRATE MATERIALS

This paper reports the results of preliminary assessment of the relati ve adherence of diamondlike carbon coatings on typical metal, ceramic, and polymeric total joint prosthesis materials. Coatings were applied , using an ion assisted method, from a hydrocarbon precursor. The latt er was generated in vacuum and allowed to condense on the workpiece su rface while simultaneously being subjected to 20-50 keV nitrogen ion b ombardment. Such ion energies lead to disruption of C-H bonds, with mo st of the hydrogen escaping in gaseous form; this leaves behind a prin cipally carbonaceous amorphous residue, i.e. DLC. A cobalt-chrome allo y, an alumina, stainless steel, and a high density polyethylene (HDPE) were coated with DLC under varying surface preparation, and ion depos ition conditions. Adhesion was measured qualitatively by means of scra tch hardness testing. The smoothness of the DLC coating on glass was e xamined by atomic force microscopy. Differences in adhesive strength a nd damage mechanisms are discussed in terms of coating conditions, and implications for performance under realistic total joint loads of 6 t o 10 MPa are considered.