E. N. D. Camargo, S. Baldissera, M. M. D. Silva, J. Otubo, Instituto Tecnologico de Aeronautica, S. J. dos Campos, Brazil; M. Ueda, National Institute for Space Research, S. J. dos Campos, Brazil
Although Nickel–titanium (NiTi) shape memory alloys are promising materials as a biomaterial due to their shape memory and superelastic properties, there is one concern which is the out-diffusion of nickel causing toxic reactions in humans, mainly in nickel hyper-sensitive patients. This work presents some preliminary results of surface modification by nitrogen implantation by plasma immersion ion implantation (PIII) in NiTi SMA. The nitrogen diffusion layer will be analyzed by Auger Spectroscopy and mechanical properties by nanoindentation techniques. The nickel release will be analyzed by immersion test on physiological serum at 37 oC and corrosion resistance by electrochemical measurements techniques as potentiodynamic polarization and electrochemical impedance measurement.
Summary: Nickel–titanium (NiTi) shape memory alloys are promising materials for surgical implants due to their shape memory and super-elasticity. Studies have also reported that nickel ions leached from the alloys cause toxic reactions in humans, more severely in nickel hyper-sensitive patients resulting in strong allergic reactions. The use of the process PIII process aims to avoid this negative characteristic of nickel release through the nitrogen implantation in the alloy surface keeping the Ni into deeper layer.
