Corrosion behaviour of titanium b type ti-12cr in 3% nacl solution

Abstract

Titanium alloy, especially titanium type Ti-12Cr for biomedical application has been a concern of many researchers recently. This titanium has excellent biocompatibility and controllable mechanical properties. Generally, titanium β type contains many alloying elements that lead to a high price. Therefore, it is interesting to develop β type with only one cheap alloying element such as Ti-12Cr that is designed as a low-cost implant material. Initially, Ti-12Cr has been developed, in particular for spinal fixation. Nowadays, the research of Ti-12Cr emphasizes only on mechanical properties. The corrosion behavior of this alloy has not been understood well yet. Therefore, corrosion characteristics of this alloy in any circumstances are necessary to investigate. This paper reports the corrosion behavior of Ti-12Cr in a salted environment using the weight loss method. Ti-12Cr samples were immersed in a 3% NaCl solution for 2, 4, and 6 weeks. Samples consist of Ti-12Cr (as-received), Ti-12Cr (ST) and Ti-12Cr (AT 30 ks). Weight of samples was measured before and after the immersing process using the digital balance. Microstructure and composition of the sample surfaces were examined by using SEM and EDX, respectively. The lowest corrosion rate after exposure for 6 weeks while the highest one is Ti-12Cr (as-received) is Ti-12Cr (AT 30 ks) that is 0,003 mmpy. The microstructure all of the samples shows black spots in the surfaces indicating corrosion has been started to occur on the samples. It was found that the corrosion is due to destruction of the chrome-oxide layer in some weak point as a result of a chemical reaction between the metal (Cr) with Cl- ions. Some oxides are formed on the surface of titanium, as indicated by a significant increment of oxygen content is the corrosive sample surface. This study indicates the corrosion resistance of Ti-12Cr (AT 30 ks) is much better than other materials in this research.