Examples of medical titanium rods used in human cardiovascular aspects include artificial heart valves, blood filters, pacemakers and artificial heart pumps.
Its main advantages are:
① High strength, good chemical stability, and excellent biocompatibility;
② Titanium is non-magnetic and rarely produces artifacts in magnetic resonance spectra (MRI);
③ The elasticity and shape recovery function of NiTi memory alloy are very suitable for medical applications. NiTi alloy is in a martensitic state at low temperature (near zero degrees) and can easily change into a shape that is easy to be introduced into the human body. When the temperature rises to body temperature A reverse phase change will occur, thereby returning to the original set shape, and generating a larger restoring force to play an orthopedic and supporting role.
In recent years, the application of NiTi shape memory alloys in vascular stents has attracted much attention. However, NiTi alloys may dissolve Ni ions under physiological conditions, thereby inducing toxicity and inflammatory reactions. To this end, researchers have conducted a large number of surface modification studies on this alloy. The main methods include surface inert coating, surface oxidation, surface activation and surface grafting of macromolecules. Although the starting points are different, they can effectively inhibit the dissolution of Ni ions and improve the corrosion resistance and biocompatibility of NiTi alloys.
