Research progress of surface modification of biomedical titanium alloy 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 to traditional stainless steel and cobalt-based alloys, titanium alloys have a lower elastic modulus, which has been shown to reduce the stress shielding effect and thus better induce and promote osseointegration. These advantages make it more suitable for clinical applications.

      However, titanium and its alloys cannot meet the clinical requirements of biomedical implants. Long-term clinical studies have observed that titanium implants have poor wear resistance, and the wear debris generated by the friction of titanium implants can cause inflammation problems and toxic effects on 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 antimicrobial properties of titanium and titanium alloys is a more economical and effective way to improve existing conventional biomaterials to meet 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. A ceramic coating with excellent wear resistance has been deposited on the titanium surface to improve the wear and corrosion properties. Commonly used wear resistant coatings include diamond-like carbon film (DLC), titanium nitride (TiN) coating, etc.

       Diamond-like carbon film (DLC)

      Diamond-like carbon film is often used as a wear-resistant coating for medical metal implants due to its high hardness, excellent wear resistance, low friction coefficient and good biocompatibility. Part of the diamond-like carbon film surface modification of the implant device has realized clinical application, has a broad application prospect in improving the wear resistance, corrosion resistance of metal components of artificial joints.

      Titanium nitride (TiN)

     TiN, which has good wear resistance and corrosion resistance, was first used in cutting tools to extend their service life. Later, titanium nitride was found to be biocompatible and began to be used in medical implants such as orthopedic surgery and dentures. At present, the main preparation methods of titanium nitride are physical vapor deposition (PVD), chemical vapor deposition (CVD) and thermal spraying.