Bioinertness and fracture toughness evaluation of the monoclinic zirconia surface film of Oxinium™ femoral head by Raman and cathodoluminescence spectroscopy.

Raman and cathodoluminescence spectroscopic methods were employed for clarifying important stoichiometric and mechanical properties so far missing in the specification of the physical origin of the structural behavior of Oxinium™ femoral head components. Spectroscopy proved helpful in rationalizing the actual physical and chemical reasons behind the mechanical integrity of the ceramic–film/metal–substrate interface, which is responsible for both the good adherence and the surface durability reported in prosthetic applications of Oxinium™ components. Raman spectroscopy coupled with the crack opening displacement (COD) method was used to evaluate the intrinsic fracture toughness of the surface oxide film. In addition, cathodoluminescence spectroscopy provided new evidences on both the oxygen vacancy gradient developed during the metal-oxidation manufacturing process and the bioinertness of Oxinium™ femoral components.