Analysis of corrosion properties of medical titanium materials.

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

1. Corrosion of titanium

Titanium is a thermodynamically unstable metal with a relatively negative passivation potential, and the standard electrode potential is -1.63V. Therefore, it is easy to form an oxide film with passivating properties in the atmosphere and aqueous solution, and has 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 penetrate into biological tissues, which can trigger physiological reactions of varying degrees; on the other hand, due to the presence of body fluids, the performance of some materials may be seriously degraded, causing rapid damage or even Invalid. The human body environment is relatively complex, which is more likely to cause the dissolution of trace elements and change the stability of the oxide layer. Slight friction can cause varying degrees of damage to the passivation film formed on the titanium surface. For example, in an oxygen-poor environment, the stability of the oxide layer is weakened. When damaged, it cannot be repaired immediately or a new oxide layer is formed, making it more likely to cause corrosion. This situation is almore unavoidable during repeated movements of the human body and the use of equipment. Plastic deformation will change the structural state of the material, thereby affecting the corrosion performance of the material. Different degrees of plastic deformation have greatly different effects on the corrosion properties of materials. During the plastic deformation process, the concentration of internal stress causes defects in the interface and grains. Therefore, plastic deformation weakens the corrosion resistance of the material.

2. Titanium corrosion mechanism

Titanium is a transition element of Group IVB. It is chemically active and has a great affinity with oxygen. In any oxygen-containing medium, a dense passivation film is easily formed on the surface of titanium. This passivation film is thin, and its thickness is usually a few nanometers to tens of nanometers. The existence of titanium alloy passivation film reduces the area of surface active dissolution and slows down the dissolution rate, thus resisting the damage caused by dissolution. In addition, the passivation film can also be automatically repaired and can quickly form a new protective film when damaged. Therefore, titanium has good corrosion resistance. The corrosion forms of titanium metal implanted in living organisms can be divided into pitting corrosion, stress corrosion, crevice corrosion, galvanic corrosion and wear corrosion, etc.