The purpose of the research was to form a Ti-Ta-N- system bioinert coating on Ti6Al4V alloy surface as well as to study its structure and properties. The main contribution of the research is in the following. Electro-explosion spraying of tantalum coating on VT6 titanium alloy surface was pioneered in the research. After that the processing of the coating by low-energy high-current electron beam and subsequent nitriding was carried out in a single technological cycle. It has been established that a nanocrystalline coating based on tantalum, nitrogen and titanium was formed as a result of the technological operations. The phase composition of the coatings has been detected. The variations in crystal lattice parameters being formed in coating of phases and coherent scallering regions of these phases depending on power density of electron beam have been determined. Structural characteristics of the coatings at nano- and microlevel have been detected. Tests of coatings for nanohardness, the Young modulus, wear resistance and friction factor have been carried out. By all technical characteristics Ti-Ta-N-system coating exceeds titanium of VT6 grade. The cause of the increase in mechanical characteristics of the Ti-Ta-N-system coating is their nanostructural state and strengthening phases. Tests for proliferation activity of fibroplasts and antimicrobial activity have shown better results in comparison with VT6 titanium alloy as well. It is due to escape of vanadium ions from VT6 alloy into nutrient cell medium and their destructive effect on cell cultures. Variations in proliferation and antimicrobial activity develop due to amplification of cell proliferation. A complex of the obtained characteristics makes it possible to recommend Ti-Ta-N-system coating for its application as a bioinert coating on different implants in furure.

The coatings of Ti-Ta-N system have been obtained for the first time. Production of bioinert coatings of Ti-Ta-N system was realized by means of promising technique of electroexplosion spraying and subsequent electron-ion-plasma modification with nitrogen ions. Titanium of VT6 grade was used as a substrate for spraying of coatings. Electroexplosion spraying with use of tantalum foil leads to formation of tantalum coating on titanium substrate. Subsequent electron-ion-plasma modification with nitrogen ions results in synthesis of the following phases: TiN, Ta and β-Ti. Average microhardness values of the coatings formed vary from 449 kgf/mm2 (E = 11.47 %) to 530 kgf/mm2 (E = 10.02 %). Electroexplosion processing promotes the increase in titanium substrate microhardness near coating – substrate interface. In volume of titanium substrate the microhardness decreases to values corresponding to reference data. Irradiation of electroexplosive tantalum coating by electron beam with subsequent nitriding leads to homogenization of structure. Optimum mode of irradiation should be considered the one at powder density of electron beam of 0.5 MW/cm2. At lower value of power density the electron beam melts the electroexplosion coating to insufficient depth. At higher values of power density the electron beam leads to boiling of the melted coating and formation of larger quantities of pores. These phenomena are caused by thermal and physical characteristics of titanium substrate.

No abstract

No abstract