Medical titanium wire It is a very corrosion resistant metal. The thermodynamic data of titanium indicate that titanium is a thermodynamic unstable metal. If titanium can be dissolved to generate Ti2+, its standard electrode potential is very negative (-1.63V), and its surface is always covered with a passive oxide film. In this way, the stable potential of titanium is stably biased to a positive value. For example, the stable potential of titanium in seawater at 25 ℃ is about+0.09V. In chemistry manuals and textbooks, standard electrode potentials corresponding to a series of titanium electrode reactions can be obtained. It is worth pointing out that in fact, these data are not directly measured, but can only be calculated from thermodynamic data. Moreover, due to different data sources, it is not surprising that different data may appear for several different electrode reactions.
The electrode potential data of the electrode reaction of titanium shows that its surface is very active, and is usually covered with the oxide film formed naturally in the air. Therefore, the excellent corrosion resistance of titanium is due to the existence of a stable, highly adherent and protective oxide film on the titanium surface. In fact, the stability of this natural oxide film determines the corrosion resistance of titanium, including titanium bars, wires and plates of titanium and titanium alloys. Of course, the corrosion resistance of various brands is different, We talked about it in the previous content of the website, but today we won't talk much about it. In theory, the P/B ratio of the protective oxide film must be greater than 1. If it is less than 1, the oxide film cannot completely cover the metal surface, so it is impossible to play a protective role. If the ratio is too large, the compressive stress in the oxide film will increase accordingly, which is easy to cause the rupture of the oxide film, and will not play a protective role. The P/B ratio of titanium varies from 1 to 2.5 with the composition and structure of the oxide film. From this basic point, titanium oxide film can have better protection performance.
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