Product Code: ICAL06_M404

Corrosion Behavior of Laser-Oxidized NiTi in Hanks' Solution
Authors:
Man Hon Wong, Department of Applied Physics, The Hong Kong Polytechnic University; - Hong Kong
F.T. Cheng, The Hong Kong Polytechnic University; Hung Hom, Kowloon Hong Kong
H.C. Man, The Hong Kong Polytechnic University; Hung Hom, Kowloon Hong Kong
Presented at ICALEO 2006

NiTi was surface treated with a pulsed Nd:YAG laser to accomplish oxidation without melting. The oxide layer was characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) to obtain information on the thickness, morphology, and the composition profile. The oxide layer was less than 100 nm thick with an average surface roughness (Ra) of about 13 nm. The corrosion behavior of the laser oxidized sample and the untreated sample was studied using electrochemical impedance spectroscopy (EIS) at open-circuit potential and cyclic polarization test in Hanks' solution at 37 C. EIS results indicated that the polarization resistance of the laser oxidized sample was about 12 times that of the untreated sample while cyclic polarization tests similarly recorded reduction of the passive current density for the laser oxidized sample by an order of magnitude.