Microstructure and corrosion behavior of porous coatings on titanium alloy by vacuum-brazed method

✍ Scribed by T.M. Lee; E. Chang; C.H. Yen

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 448 KB
• Volume: 77B
• Category: Article
• ISSN: 1552-4973
• DOI: 10.1002/jbm.b.30440

✦ Synopsis

Abstract

The microstructural evolution and electrochemical characteristics of brazed porous‐coated Ti‐6Al‐4V alloy were analyzed and compared with respect to the conventionally 1300°C sintering method. The titanium filler metal of low‐melting‐point (934°C) Ti‐15Cu‐15Ni was used to braze commercially pure (CP) titanium beads onto the substrate of Ti‐6Al‐4V alloy at 970°C for 2 and 8 h. Optical microscopy, scanning and transmission electron microscopy, and X‐ray diffractometry (XRD) were used to characterize the microstructure and phase of the brazed metal; also, the potentiostat was used for corrosion study. Experimental results indicate that the bead/substrate contact interface of the 970°C brazed specimens show larger contact area and higher radius curvature in comparison with 1300°C sintering method. The microstructure of brazed specimens shows the Widmanstätten structure in the brazed zone and equiaxed α plus intergranular β in the Ti‐6Al‐4V substrate. The intermetallic Ti~2~Ni phase existing in the prior filler metal diminishes, while the Ti~2~Cu phase can be identified for the substrate at 970 for 2 h, but the latter phase decrease with time. In Hank's solution at 37°C, the corrosion rates of the 1300°C sintering and the 970°C brazed samples are similar at corrosion potential (E~corr~) in potentiodynamic test, and the value of E~corr~ for the brazed sample is noble to the sintering samples. The current densities of the brazed specimens do not exceed 100 μA/cm^2^ at 3.5 V (SCE). These results suggest that the vacuum‐brazed method exhibits the potentiality to manufacture the porous‐coated specimens for biomedical application. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006