Corrosion behaviour of SLM CoCrMo alloy in simulated body fluids

Traditional endoprosthesis are widely used to replace joint surfaces damaged by severe trauma or degenerative articular disease. Typical metallic biomaterials used to fabricate implant devices include austenitic stainless steels, Co-Cr and Ti alloys. In particular, the use of high-strength Co Cr based alloys for improving the durability of such devices has attracted much attention in the past years because of their excellent properties, including high mechanical strength, good biocompatibility, high wear and corrosion resistance . Although these materials have been used successfully for over 5 decades, in the case of some specific joint surfaces frequent failures and patient’s dissatisfaction have been reported. The reasons for these failures were related to a number of factors, such as: limited availability of prosthesis size and shape, difference in mechanical properties between bone and implant materials, unsatisfactory osteointegration, foreign body reaction induced by inflammatory cells .Selective laser melting (SLM) is a very promising technique that can overcome some of these issues. In fact, this technique allows obtaining complex shapes, completely customizable and scalable prostheses through the consolidation of metal powders layer by layer. It is, therefore, possible to control the microstructure characteristics of the product and to manufacture dense components, porous graded or fully customized architectures, improving osteointegration and bone adaptation Biofunctionality and biocompatibility are fundamentals factors for the selection of biomaterial alloys and the corrosion resistance of metal implants in the body fluids is closely related to their biocompatibility. The materials fabricated with SLM technology seem to be promising in terms of corrosion resistance, but their behavior in biological environments has not been studied in depth. So, this research aims at investigating the corrosion behaviour of the CoCrMo alloy, fabricated with different sets of process parameters in solutions simulating biological fluids both in the presence and in absence of inflammatory conditions.