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Ti -addition to hydroxyapatites [Ca10(PO4)6(OH)2–HA] with 5.0 wt.% Ti content, was successfully deposited on titanium substrate by mechanical alloying (MA) method. The X-ray Diffraction (XRD) data indicated that some changes take place in the HA lattice as well as in the Ti substrate. The coating thickness of the as-synthesized sample was about 91.1 μm. Ti incorporation into the apatite structure caused lattice shrinkage. The heat treated sample shows that dominant phase was HA up to 600°C. The Ti -doped HA steadily transformed to β- and α-tricalcium phosphate at 800°C. Scanning Electron Microscopy (SEM) observations revealed cracks above the temperature of 600°C. The presence of cracks could be due to the difference in coefficients of thermal expansion of Ti -doped HA and Ti -alloy substrate.

The research represents a newly-developed simple method to apply hydroxyapatite by gas-dynamic spraying. The hydroxyapatite coating formed on VT1-0 titanium were obtained following the mechanochemical interaction of hydroxyapatite and titanium with gas-dynamic spraying. The article proposes the phase composition, surface morphology, and roughness of these coatings. The surface morphology of the hydroxyapatite coating had a porous structure. The transverse sections of coatings were researched to study the interaction of hydroxyapatite with a titanium base. It was shown that the coatings mainly form in the titanium bedding depressions. Analyzing the roughness parameter Ra of hydroxyapatite coatings made it possible to conclude that the samples obtained fell almost within the same limits. These data are within the roughness optimum (Ra = 2-3 μm) of artificial surfaces aimed to manifest the best human osteogenic properties. The analyzed phase composition enabled to establish the fact that the hydroxyapatite layer composition does not change significantly after spraying that is important for biomedical use.

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