C–HAp composite layers deposited onto AISI 316L austenitic steel

Abstract

Despite significant progress made in the selection of metallic materials used in various types of medical implants, their toxic effects on the human body have yet to be entirely eliminated. This is especially important in the case of metallic materials used in long-term medical implants. Hydroxyapatite and carbon coatings appear to be particularly interesting in this field. Surface engineering techniques can be applied to obtain a major improvement of biocompatibility, corrosion and wear resistance of metallic biomaterials without losing their beneficial mechanical properties. Carbon coatings were synthesized using RF PACVD method, whereas HAp layers were subsequently deposited by PLD technology. Morphology and chemical composition of composite layers were determined using SEM. X-ray diffraction was applied for phase composition investigation. Potentiostatic and potentiodynamic characteristics in Tyrode's solution allowed to determine the corrosion features of C–HAp layers. Adhesion of synthesized coatings was determined using nanoindentation technique. Results obtained in the present investigation prove the good influence of carbon interlayer on adhesion of HAp coatings, however the corrosion feature investigation gave ambiguous results. Carbon interlayer has been found to noticeably improve the corrosion features of AISI 316L alloy, however subsequent deposition of HAp layer resulted in decreased corrosion parameters, which can be an effect of applied PLD deposition technique.