Diamond-like carbon coatings for biomedical applications

Abstract

Diamond-like carbon (DLC) films were prepared by introducing hydrocarbon gasses into a saddle field source that produces a neutral beam of carbon atoms which are deposited on a range of substrates. Good adhesion was achieved on stainless steels, cobalt chrome alloy, titanium alloy (TiVAl), polymers and quartz. Deposition parameters were varied to produce films with a range of refractive indices. Refractive index has previously been reported to be directly related to the mechanical properties of films. Hardness was measured on films with refractive indices (measured at 675 nm) in the range 1.85-2.45. Hydrogen content and impurity levels were below 1% and sp3 content was 55-75%. Films exhibited compressive stress and had coefficient of friction values between 0.08 and 0.25 against ultra high molecular weight polyethylene (UHMWPE). Films, when examined by SEM and AFM, were smooth down to nanonmetre scale. Cellular growth on coated titanium alloy gave results that show good biocompatibility, as determined by cytotoxicity, and adhesion using murine fibroblasts.