1. Effect of voltage on microstructure and corrosion resistance of microarc oxidation coatings on CP-Ti.
- Author
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Chang, S. Y., Lin, H. K., Tsao, L. C., Huang, W. T., and Huang, Y. T.
- Subjects
CORROSION resistance ,SURFACE coatings ,COATING processes ,PROTECTIVE coatings ,CORROSION engineering ,CORROSION & anti-corrosives - Abstract
The surface modification of commercially pure titanium (CP-Ti) by microarc oxidation (MAO) under different voltages was investigated using 1%H
3 PO4 solution as an electrolyte. The microstructure, phase composition and elemental distribution of ceramic coatings were investigated using scanning electron microscopy (SEM) and X-ray diffraction. The corrosion behaviour of the coating was also examined by potentio dynamic polarisation testing in a 3-5 wt-%NaCl solution. Micropore oxide films were formed on all the sample groups by MAO. The thickness and micropore size of the MAO coating increased with the increasing voltage. Energy dispersive X-ray spectroscopy results indicate that Ti, O and P became incorporated into the MAO coatings. At a low voltage of 250 V, the MAO coatings were composed of amorphous, P2 O5 , TiP2 O7 and titania phases (rutile and anatase). Variation of treatment voltages increased the ceramic coatings from an amorphous structure to a phase structure, and the P2 O5 phase disappeared. The corrosion potential Φcorr of the MAO sample shifted towards nobler directions, and the corrosion density /corr fell significantly compared with that of the bare CP-Ti. Corrosion testing showed that the sizes of the micropore of the MAO samples obviously decrease, and the MAO surface becomes smooth. [ABSTRACT FROM AUTHOR]- Published
- 2014
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