The effect of thermal oxidation on the corrosion resistance of β-type titanium alloy Ti-29Nb-13Ta-4.6Zr (TNTZ) in simulated body fluid

Abstract Titanium alloys are widely used as medical biomaterials due to their superior properties. One promising alloy is a β-type titanium alloy Ti-29Nb-13Ta4.6Zr (TNTZ). This alloy consists of non-toxic and non-allergenic elements, making it safe for use as an implant material. Compared to stainless steel and cobalt-chromium (CoCr), TNTZ has the advantages of high strength, good biocompatibility, a Young’s modulus close to that of human bone, and superior mechanical performance. Although corrosion resistant, TNTZ can degrade when the oxide layer (TiO 2 ) on the surface is lost or fails to reform in simulated body fluid (SBF) solution. This condition has the potential to cause toxicity or allergic reactions, so surface treatment is needed to increase the stability of the oxide layer. One method used is the thermal oxidation process, with the aim of forming a thicker oxide layer to make the material more resistant to corrosion. Testing was carried out using the potentiodynamic polarization method in Kokubo SBF media with 13 samples, where 12 samples underwent oxidation treatment with variations in temperature and time, while 1 sample served as a control. The results show that the corrosion resistance of TNTZ is greatly influenced by the temperature and duration of oxidation. The corrosion rate tends to increase at higher temperatures and longer times. For example, at 800°C the corrosion rate reached 472.53 mmpy, while at 600°C it was only 28.5 mmpy. This increase in corrosion rate was influenced by surface roughness due to the oxidation process, which accelerated the formation of electrochemical poles.