| Abstract: |
The excellent corrosion resistance and biocompatibility of titanium make of it the material to choose for biomedical applications. Cold spraying, as a new coating technique, can be used to deposit protective Ti coatings onto less performing materials such as stainless steel and Co-Cr alloys, commonly used for biomedical implants. In addition, Cold Spray has the advantage, in comparison with conventional thermal spray techniques, to permit to deposition of oxygen-sensitive materials. The impurity contents, such as oxygen in particular, may be therefore carefully controlled. In fact oxygen has a great influence on the ductility and strength of Ti and consequently also on the biocompatibility and bone-growth properties. In this study, Cold Sprayed Ti coatings were prepared on Co-Cr alloy substrates by using different spray process conditions. The microstructure of coatings was observed by SEM and the inner porosity was estimated by image analysis. Oxygen and nitrogen contents were investigated on a set of free standing deposits obtained using different process parameters. In the same way, the roughness and microhardness of deposits, such as the adhesion strength with the substrate, were measured. Finally, the corrosion performance of the coatings was evaluated by mean of open circuit potential measurement (OCP) and potentiodynamic polarizations scans. The electrochemical response was therefore discussed and compared to the corrosion behaviour of the Co-Cr alloy substrate and the bulk Titanium.
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