Corrosion and ion release behavior of ultra-fine grained bulk pure copper fabricated by ECAP in Hanks solution as potential biomaterial for contraception

Ultra-fine grained (UFG) bulk pure copper has been successfully fabricated by equal-channel angular pressing (ECAP), with the grain size about 380 nm after 8 passes. The potentiodynamic polarization results of the ECAP copper specimens tested in Hanks solution revealed that the corrosion current of UFG copper is higher than that of the coarse grained copper. The cupric ion release behaviors of UFG copper immersed in Hanks solution for 30 days only displayed a burst release during the first 3 days (in comparison to the 1-2 months for the conventional Cu) from 115 μg/day to 12.5 μg/day, after which the ion release remained constant and slow. During the immersion experiments, Cu₂O was the only corrosion product found on the surface and it took 10 days or so to form a uniform Cu₂O layer. Uniform corrosive damage on the surface and few localized corrosion is observed. The above results indicate that UFG copper could have high potential as biomedical materials for contraception.