As an important functional material, titanium metal has been 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.
Corrosion of titanium
Titanium is a thermodynamically unstable metal with a negative blunt potential and a standard electrode potential of -1.63V. Therefore, it is easy to form an oxide film with passivation property and good corrosion resistance in atmosphere and aqueous solution.
Corrosion resistance of titanium alloys in living organisms
It is very important to study the corrosion resistance of medical materials. On the one hand, some metal ions or corrosion products of the implanted materials infiltrate into the biological tissues, which can cause physiological reactions of different degrees. On the other hand, due to the presence of body fluids, the properties of some materials may be seriously degraded, resulting in rapid damage or even failure.
The human body environment is relatively complex, it is easy to cause the dissolution of trace elements, change the stability of oxide layer. Slight friction can make the passivation film formed on the surface of titanium suffer varying degrees of damage, such as in the oxygen-poor environment, the stability of the oxide layer is weakened, and when damaged, it can not be repaired immediately or a new oxide layer can be formed, which is more likely to cause corrosion. And 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 materials, and then affect the corrosion properties of materials. The influence of plastic deformation on the corrosion properties of materials is quite different.
In the process of plastic deformation, the concentration of internal stress leads to defects in the interface and grain, so the plastic deformation will weaken the corrosion resistance of the material.
