Nanotechnologies for the Formation of Medical Implants Based on Titanium Alloys with Bioactive Coatings

The main approaches to the formation of modern functional materials for medical implants, including the principles of material choice on the criteria of their biochemical and biomechanical compatibility and their technological effectiveness, are represented in this review. Titanium alloys are considered the most prospective and extended materials for implants in traumatology, orthopedics, and stomatology. The trend over the last decade has been to exclude alloying components that may cause local allergic reactions on living tissues or general toxic effects on an organism from the structure of titanium alloys. One compromise to preserve high biochemical compatibility with the necessary increase in the mechanical properties of titanium alloys is based on the formation of submicrocrystalline (SMC) or nanostructured (NS) states in commercially pure titanium. The prospect of using SMC and NS titanium as a material for manufacturing implants is proven. An analysis of the results of experimental and theoretical research of the diffusion features on intergranular areas is carried out, and the role of diffusion-controlled processes in the formation of a microstructure of metals and alloys, as well as the microstructured state, is discussed. The efficiency of computer simulation on an atomic level in establishing the dependence of diffusion characteristics on intergranular areas from the average grain size and the structural state of internal boundaries of section is proven. A short description of simulation and semi-industrial methods of the formation of SMC and NS states in metals and alloys by means of severe plastic deformation- which are known as materials related to the top-down approach, assuming the initial structure is crushed to nanosized components- is presented. Special attention is given to the recent developed of low-cost and high-efficiency technological schemes for the mass production of nanostructured titanium alloys for medical purposes, including radial-shift and screw rollings, along with a combination of traditional methods of mechanical-thermal processing, which make it possible to receive an assortment of the titanium and its alloys necessary for the mass production of medical implants and tools.