Microstructural Characterization of Biofunctionalized Titanium Foams

Titanium and its alloys are widely used in orthopaedic and dental implants due to their mechanical properties and high corrosion resistance. It is known that porous metals can increase the in vivo lifetime of metallic implants by decreasing the effective Young’s modulus of implant material to match that of bone as well as increasing the interfacial bond between living cells and implant materials via compositional or structural modification [1–4]. The present study aims at processing, biofunctionalizing and characterization of titanium foams having porosity from nano- to macro-scale. In order to reach that aim, first titanium foams were produced by powder metallurgy with space-holder technology. Powders of Ti and urea having average sizes of 32 and <500 µm, respectively, were blended in a planetary ball mill for 3h. The green compacts containing 30, 50, and 70 vol.% of urea (corresponds to 30, 50, and 70 vol.% of nominal porosity, respectively) were prepared by cold pressing in a stainless steel die under 350 MPa. After compacting, the space holder was removed by immersing the samples in water for 9, 10, and 11h for 30, 50, and 70 vol.% of nominal porosity, respectively. Finally, Ti foams were sintered at 1250 ºC for 3 h under vacuum. The anodic treatment was performed at 200 V for 1 min in H3PO4 (1M). After processing, porosity values were determined by image analysis technique using Leica DM2500 OM and Image J 1.37v image analysis software and microstructures were investigated by FEI Nova 200 field emission gun scanning electron microscope (FEG-SEM), equipped with EDAX energy dispersive X-ray spectroscopy (EDS).