Heat Treatment and Anodic Oxidation Process of SP700 Titanium Alloy
ABSTRACT:Objective To fabricate nanoporous film on SP700 titanium alloy by electrochemical anodic oxidation. Methods The dynamic polarization curves and I-t curves were conducted using AutolabPGSTAT30 electrochemical workstation, which adopted three-electrode system, for instance, graphite as auxiliary electrode, SCE as reference electrode, and sample as working electrode. The micro-morphology of porous films on the matrix was observed by SEM. Meanwhile, the effects of process parameters such as heat treatments, anodic oxidation voltage and composites of electrolytes on anodic oxidation behavior were investigated. Results The relative content of α and βphase of titanium alloy changed after solid solution-aging treatment, which made oxygen ion reacted ac-cording to the inner stress on electrochemical reaction interface. Thus, smoother films and excellent corrosion resistance were ob-tained. The F- was a necessary condition of the formation of nanoporous films. The intensity of nanoporous and the thickness of films increased with the increase of F- concentration, what′s more, the diameter of porous decreased as the F- concentration in-creased. The thickness of oxide films increased with the increase of anodic oxidation voltage in certain range. However, excessively high voltage would damage the stability of the oxide films. Conclusion Porous films could be formed on the matrix of titanium alloy by electrochemical anodic oxidation, and gained ideal corrosion resistance. The corrosion resistance of titanium alloy increased un-der conditions of solid solution-aging treatment.
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