RF-Magnetron Sputtering법으로 TiN, ZrN 및 HA를 코팅한 Ti 합금의 전기화학적 특성

Abstract

Electrochemical characteristics of Cp-Ti and Ti alloys coated with TiN, ZrN, and HA using RF-magnetron sputtering method were studied. The Ti containing Nb, Zr up to 13.0 wt% were melted by using a vacuum furnace and then homogenized for 24hrs at 1050℃. The samples were cut and polished for corrosion test and coating. The specimens were coated with TiN, ZrN and HA, respectively, by RF-magnetron sputtering method. The microstructures were conducted by using optical microscope(OM), X-ray diffraction meter(XRD), energy dispersive X-ray spectroscopy(EDX) and field emission scanning electron microscope(FE-SEM). The corrosion behaviors were investigated using potentiostat(EG&G Co, 263A. USA) and electrochemical impedance spectroscopy(10 mHz ～ 100 kHz) in 0.9% NaCl solution at 36.5±1℃. Corrosion surface was observed using OM and FE-SEM. The results were as follows: 1. From the microstructure analysis, Cp-Ti showed the acicular structure of α-phase and Ti-6Al-4V showed the micro-acicular structure of α+β phase. Needle-like martensitic structure of near-β type was observed in the case of Ti-13Nb-13Zr alloy. 2. From the corrosion test results of Ti alloy, corrosion potential of Cp-Ti , Ti-6Al-4V, and Ti-13Nb-13Zr were -101 mV, -417 mV, and -328 mV. Corrosion current density of Cp-Ti , Ti-6Al-4V , and Ti-13Nb-13Zr showed 1.82×10-1 ㎂/㎠, 1.42×10-2 ㎂/㎠, and 3.71×10-1 ㎂/㎠. 3. From the analysis of TiN, ZrN and HA coated layer analysis, TIN and ZrN coated surface showed columlar structure with 600 nm and 100 nm thickness, respectively. Columlar structure was grown along the (111) and (200) in the case of TiN coated layer, and along the (111) and (220) in the case of ZrN coated layer. HA coated layer showed columnar structure growth along (102) and (202). 4. The corrosion resistance of TiN, ZrN and HA coated Ti alloys were higher than those of the non-coated Ti alloys in 0.9% NaCl solution, indicating better protective effect. Corrosion resistance of coated Ti alloys increased in the order of TiN, ZrN, and HA coating. 5. From the analysis A.C. impedance analysis in 0.9% NaCl solution, Rp value of TiN coated Ti alloy showed 3.58×108 Ωcm2 which was higher than those of other Ti alloy. Polarization resistance(Rp) values increased in the order of Cp-Ti, Ti-6Al-4V, and Ti-13Nb-13Zr alloy.