HA/Ti 복합층 코팅한 Ti-30Ta-(3~15)Nb 합금의 전기화학적 특성

Abstract

Electrochemical properties of Ti-30Ta-(3~15)Nb alloys coated by HA/Ti compound layer have been studied by various electrochemical method. Ti-30Ta binary alloys contained 3, 7, 10, 15 wt% Nb contents were manufactured by the vacuum furnace system. and then specimen was homogenized for 24 hrs at 1000℃. The samples were cut and polished for corrosion test and coating. and then it was coated with HA/Ti compound layer by magnetron sputter. The non coated and coated morphology of Ti alloy were analyzed by x-ray diffractometer(XRD) and filed emission scanning electron microscope(FE-SEM). The corrosion behaviors were investigated using potentiodynamic test and A. C. impedance test (PARSTAT 2273, USA) in 0.9% NaCl solution at 36.5 ± 1 ℃.

The results were as follows;

1. From XRD analysis, homoginazed Ti-30Ta-(3~15wt%)Nb alloys showed the α+β phase, and β phase peak was predominantly appeared in the case of increasingly Nb contents.

2. From the microstructure analysis, The microstructures of Ti alloy were transformed from needle-like structure to equiaxed structure as Nb content increased.

3. From the analysis of coating surface, HA/Ti composite surface uniformed coating layer with 750nm thickness.

4. The polarization resistance of HA/Ti composite coated Ti-alloys were higher than those of the non-coated and HA coated samples in 0.9% NaCl solution at 36.5 ± 1 ℃. especially, corrosion resistance of Ti-Ta-Nb system increased as Nb content increased.