Biocompatibility evaluation and corrosion resistance of tungsten added Co-30Cr-4Mo-1Ni alloy

Biomaterials are continuously being developed to overcome the drawbacks of existing materials and provide improved function in artificial organs. Currently Co-Cr based alloys are used in many medical applications such as hip and knee implants which still require modification to better perform. In this article, therefore, the influence of tungsten allying element on electrochemical corrosion resistance and biocompatibility behaviour of a recently developed Co-30Cr-4Mo-1Ni alloy composition were investigated. The tungsten modified alloys were prepared by using a high temperature vertical vacuum casting technique at five different weight percentages (0-4wt.% tungsten). The electrochemical corrosion behaviour of all the samples under NaCl solution was studied by using potentiodynamic scan method. The corrosion characteristics were investigated in terms of corrosion potential (Ecorr) and corrosion current density (Icorr). From the results of the analysis, it was observed that out of all samples, an alloy with 2wt.% of tungsten in composition (i.e. Co-30Cr-4Mo-1Ni-2W) exhibited better corrosion resistance. Furthermore, histopathological evaluations in subcutaneous tissue were performed in rats according to the standard ISO 10993 to examine the biocompatibility of the prepared samples. The results showed no evidence of inflammatory cell migration, no epidermal necrosis, no vacuolar degeneration of basal cell, no adnexal atrophy and vesicle formation of any samples. The obtained findings indicate that Co-30Cr-4Mo-1Ni-2W can be used in biomedical applications including femoral component of hip and knee implants.