Ti-Ta-Zr합금의 전기화학적 특성에 미치는 HA/TiN 코팅의 영향

Abstract

Electrochemical characteristics of Ti-30Ta-xZr alloys coated with HA/TiN by using magnetron sputtering method were studied. The Ti-30Ta containing Zr(3, 7, 10 and 15 wt%) were 10 times melted to improve chemical homogeneity by using a vacuum furnace and then homogenized for 24hrs at 1000℃. The specimens were cut and polished for corrosion test and HA/TiN coatingand then coated with TiN and HA/TiN, respectively, by using DC and RF-magnetron sputtering method. The analysis of coated surface and coated layer were carried out by using optical microscope(OM), field emission scanning electron microscope(FE-SEM) and X-ray diffractometer(XRD). The electrochemical characteristics were examined using potentiodynamic (- 1500 mV∼+ 2000 mV) and A.C. impedance spectroscopy(100 kHz ~ 10 mHz) in 0.9% NaCl solution at 36.5±1℃.

The results were as follows;

1. From the microstructure analysis, homogenized Ti-30Ta-xZr alloys showed needle-like structure. In case of homogenized Ti-30Ta-xZr alloys, α-peak was increased with increasing Zr content.

2. From the analysis of TiN and HA coated layer, the thickness of TiN and HA coated layer showed 400 nm and 100 nm , respectively.

4. From the polarization behavior in 0.9% NaCl solution, the corrosion resistance of HA/TiN-coated Ti-30Ta-xZr alloys were higher than that of the HA-coated Ti-30Ta-xZr alloys, indicating better protective effect.

5. From the A.C. impedance in 0.9% NaCl solution, polarization resistance(Rp) value of HA/TiN coated Ti-30Ta-xZr alloys showed 8.40×105 Ωcm2 which was higher than that of HA-coated Ti-30Ta-xZr alloys.