Hf添加入Ti-30Nb-1Fe與Ti-40Nb合金 於電化學腐蝕行為之探討

Abstract

本研究針對不同Hf含量(1~4%)之Ti-30Nb-1Fe-xHf與Ti-40Nb-yHf生醫用合金，分別在0.9%NaCl(pH 5.6)與0.2%NaF(pH 4)溶液中，以極化試驗及浸泡試驗來探討合金之耐腐蝕性質，並以掃描式電子顯微鏡觀察合金浸泡於含氟離子溶液後之表面形貌，再以X光電子能譜儀分析合金於含氟離子浸泡試驗後之表面之化學組成。 研究結果指出，Ti-30Nb-1Fe-xHf合金之抗腐蝕能力以Ti-30Nb-1Fe-1Hf最佳；Ti-40Nb-yHf合金之抗腐蝕能力則無明顯差異。觀察合金浸泡於含氟離子溶液之表面形貌，推論Ti-30Nb-1Fe-xHf合金其腐蝕行為屬於選擇性腐蝕(selective corrosion)，而Ti-40Nb-yHf合金其腐蝕行為屬於均勻性腐蝕(uniform corrosion)。另外，合金浸泡後的表面化學組成為氫氧化物與TiO2及Nb2O5組成之金屬氧化物，但並無發現相關之氟化物。

The purpose of this research is to investigate the electrochemical corrosion behaviros of Ti-30Nb-1Fe-xHf and Ti-40-Nb-yHf (x, y= 1, 2, 3, and 4 wt%) alloys in 0.9%NaCl (pH=5.6) and 0.2%NaF (pH=4.0) solutions, utilizing potentiodynamic polarization and immerse tests. After testing, the surfaces of the alloys were examined by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results reveal that the corrosion resistance of Ti-30Nb-1Fe-1Hf alloy is the best among Ti-30Nb-1Fe-xHf alloys studied. Whereas, for Ti-40-Nb-yHf alloys, no significant difference in corrosion resistance can be obtained with different Hf content. The analyses of surface morphologies of the Ti-30Nb-1Fe-xHf alloys after immersed in flouride solution suggest that the corrosion behavior is a selective type. On the other hand, a uniform corrosion mode is responsible for Ti-40-Nb-yHf alloys. The constituents on the surfaces of both types of alloy consist of hydroxide, TiO2 and Nb2O5, but not fluoride.