Abstract
In this work, bioceramic coatings were formed on Ti6Al4V titanium alloy using a combined technique of plasma electrolytic oxidation followed by gas detonation spraying of calcium phosphate ceramics, based on hydroxyapatite. Plasma electrolytic oxidation was carried out in electrolytes with various chemical compositions, and the effect of electrolytes on the macro and microstructure, pore size and phase composition of coatings was estimated. Three types of electrolytes based on sodium compounds were used: phosphate, hydroxide, and silicate. Plasma electrolytic oxidation of the Ti–6Al–4V titanium alloy was carried out at a fixed DC voltage (270 V) for 5 min. The sample morphology and phase composition were studied with a scanning electron microscope and an X-ray diffractometer. According to the results, the most homogeneous structure with lower porousness and many crystalline anatase phases was obtained in the coating prepared in the silicate-based electrolyte. A hydroxyapatite layer was obtained on the surface of the oxide layer using detonation spraying. It was determined that the appearance of α-tricalcium phosphate phases is characteristic for detonation spraying of hydroxyapatite, but the hydroxyapatite phase is retained in the coating composition. Raman spectroscopy results indicate that hydroxyapatite is the main phase in the coatings.
Highlights
In modern medical practice, implants made of titanium or titanium alloys are widely used to replace damaged or defective tissue areas [1]
In this work, medical titanium alloys Ti–6Al–4V are supposed to be used as substrates, on which bioceramic layers are applied in a specific sequence
As the material of such coatings, metal oxides with a specific phase composition can be used and coatings of calcium phosphate compounds based on hydroxyapatite
Summary
Implants made of titanium or titanium alloys are widely used to replace damaged or defective tissue areas [1]. To reduce the negative impact of such factors, it is necessary to create a transition zone between the implant and the bone, which can have a strong connection with the implant material and a macro and microstructure acceptable to the body Such a zone should be obtained in a coating with a developed morphology and a specific porosity for more effective implant engraftment. As the material of such coatings, metal oxides with a specific phase composition can be used (for example, for a titanium substrate—a TiO2 anatase film) and coatings of calcium phosphate compounds based on hydroxyapatite. These coatings increase the osseointegration of the implant surface and have improved adhesive properties [3,4,5]. The combination of “Ti-TiO2-HA” allows combining the high mechanical properties of the base material and the coating biological qualities, which give the implant surface properties as close as possible to the properties of bone tissue, which improves the ability of the implant to integrate with the organism
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