Medical titanium material As an important functional material, it is widely used in aerospace, energy industry, medical supplies and other fields due to its low density, high specific strength and good corrosion resistance.

1、 Corrosion of titanium

Titanium is thermodynamically unstable metal, with relatively negative passivation potential and standard electrode potential of -1.63V. Therefore, it is easy to form a passivating oxide film in the atmosphere and aqueous solution, with good corrosion resistance.

1. Corrosion resistance of titanium in different media

It is very important to study the corrosion resistance of medical materials. On the one hand, some metal ions or corrosion products of implanted materials infiltrate into biological tissues, which can cause physiological reactions to varying degrees; On the other hand, due to the presence of body fluid, the performance of some materials may decline seriously, resulting in rapid damage or even failure. The human environment is relatively complex, which is more likely to cause the dissolution of trace elements and change the stability of the oxide layer. The passive film formed on the titanium surface can be damaged to varying degrees by slight friction. For example, in the oxygen poor environment, the stability of the oxide layer is weakened, and when it is damaged, it cannot be repaired immediately or a new oxide layer is formed, which is more likely to cause corrosion. This kind of situation is almost unavoidable in the repeated movement of the human body and the use of equipment. Plastic deformation will change the microstructure of the material, which will affect the corrosion performance of the material. The influence of plastic deformation on the corrosion property of materials is different. In the process of plastic deformation, the internal stress concentration causes defects in the interface and grains, so plastic deformation will weaken the corrosion resistance of materials.

2. Corrosion mechanism of titanium

Titanium is a transition element of the IVB group. It is chemically active and has great affinity with oxygen. In any oxygen containing medium, the surface of titanium is easy to form a dense passive film, which is thin and usually several nanometers to tens of nanometers thick. The existence of titanium alloy passive film reduces the area of surface active dissolution and the dissolution rate, thus resisting the damage caused by dissolution. In addition, the passive film can also be automatically repaired, and when damaged, a new protective film can be quickly formed. Therefore, the corrosion resistance of titanium is good. The metal titanium implanted in organism can be divided into pitting corrosion, stress corrosion, crevice corrosion, galvanic corrosion and abrasion corrosion

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