Aluminium forming alloys for surgical implants
With the aid of thermal oxidation process, a highly specialised alloy, the Fe-20Cr-5Al alloy (PM 2000) that has been coated with alumina has the potential to be utilised as biomaterial. Unlike currently used biomaterials, this novelty includes neither nickel which is considered as a potentially allergenic and carcinogenic element, nor the geo-strategic cobalt element. The final product displays excellent mechanical properties that are comparable or superior to most of the commonly used biomaterials. Particularly the alloy in its pre-oxidised condition is shown to have high performance in terms of corrosion resistance and exhibits very low ion release even under friction conditions. Most importantly, the new material displays very good biocompatibility behaviour similar to that of well-known materials, such as alumina. Compared to other materials with bioinert coatings, the PM2000 displays an extremely high fatigue limit without being easily cracked under conditions of deformation of the coating. The advanced thermal oxidation technique offers increased capabilities of developing a very thin outer alumina layer of about 5 microns. The method also allows a significant reduction in density in comparison to cobalt-chromium alloys. This surface modification technique constitutes an easy, non-contaminant and cost-effective process. Despite the component's shape, it provides homogeny in terms of coating thickness without any modifications in the dimensional tolerance of the component. Due to its soft ferromagnetic behaviour, the PM2000 can not be employed under strong magnetic fields, such as those found in Nuclear Magnetic Resonance (NMR). This makes it unsuitable to be employed in certain medical devices, however, alternative control techniques are sought to this end. Collaboration is sought with producers of surgical impants for specialised components applications.