Laser oxidation of NiTi for improving corrosion resistance in Hanks' solution


NiTi plates were surface treated to form an oxide film with a pulsed Nd:YAG laser in ambient air using a carefully selected set of processing parameters. The oxidized samples had a yellowish interference color. The temperature rise of the sample bulk was only about 20 °C though the surface temperature reached could be much higher. Atomic force microscopy (AFM) recorded an average surface roughness of 12.5 nm for the oxidized surface. X-ray photoelectron spectroscopy (XPS) showed that the surface Ni/Ti atomic ratio was reduced from 0.30 for the mechanically polished samples to 0.17 for the oxidized samples, indicating improved biocompatibility. Measurements using electrochemical impedance spectroscopy (EIS) at open-circuit potential recorded a 15.8-fold increase in corrosion resistance in Hanks' solution. In cyclic polarization tests, the laser oxidized NiTi samples did not show pitting up to an applied potential of 1550 mV SCE, similar to bare NiTi, but the passive current density was an order of magnitude lower. The present study positively indicates the feasibility of employing laser oxidation for improving the corrosion resistance of NiTi.Department of Industrial and Systems Engineerin

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oaioai:ira.lib.polyu.edu.hk:10397/16712Last time updated on 2/10/2018

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