Research progress on surface modification of biomedical titanium alloys to improve wear resistance

Titanium and its alloys are the most commonly used metal materials for medical implants in orthopedic and dental applications because of their low density, high strength, non-toxicity and excellent corrosion resistance. Compared with traditional stainless steel and cobalt-based alloys, titanium alloys have a lower elastic modulus, and the low elastic modulus has been proven to reduce the stress shielding effect, thereby better inducing and promoting bone integration, which makes it more suitable for clinical medical applications.

However, titanium and its alloys can not meet the clinical requirements of biomedical implants. Long-term clinical research and observation have found that titanium implants have poor wear resistance, and the wear debris generated by the friction of titanium implants will cause inflammation and toxic effects on the human body.

In order to improve the biological and tribological properties of titanium alloys, the introduction of surface modification technology to enhance the biological activity, wear resistance and antibacterial properties of titanium alloys and titanium alloys is a more economical and effective way to improve existing conventional biomaterials to meet the current and evolving clinical needs.

At present, a variety of physical and chemical methods have been used to improve the wear and corrosion properties of titanium alloys by depositing a layer of ceramic coating with excellent wear resistance on the surface of titanium alloys. Commonly used wear-resistant coatings are diamond-like carbon film (DLC), titanium nitride (TiN) coating and so on.

Diamond-like carbon Film (DLC)
Because of its high hardness, excellent wear resistance, low friction coefficient and good biocompatibility, diamond-like carbon film is often used as a wear-resistant coating for medical metal implants. Some of the implants modified by diamond-like carbon film have been applied in clinical applications, and have broad application prospects in improving the wear and corrosion resistance of metal components of artificial joints.

Titanium nitride (TiN)
TiN, which has good wear and corrosion resistance, was initially applied to cutting tools to extend their service life, and later titanium nitride was found to be biocompatible and began to be applied to medical implants such as plastic surgery and dentures. At present, the main methods for preparing titanium nitride are physical vapor deposition (PVD), chemical vapor deposition (CVD) and thermal spraying.