Effects of superplastic forming on modification of surface properties of Ti alloys for biomedical applications

In the present work, both the surface chemical contamination and the mechanical alteration of Titanium Grade 5 and Grade 23 plates subjected to superplastic forming for the manufacturing of highly customized biomedical prostheses have been investigated. As case study, a cranial implant was considered. Free Inflation tests were conducted in order to determine the material behavior to be implemented in the numerical model used for simulating the implant manufacturing by superplastic forming. Glow Discharge Optical Emission Spectrometry analyses, nano-indentation tests and metallographic analyses allowed to relate the mechanical alteration to the Oxygen enrichment due to the environmental exposition during processing. Finally, real implants were produced and Cytotoxicity tests were conducted on the most oxidized part in order to determine the effect of the oxygen enrichment on the cells viability.