Effect of microplasma modes and electrolyte composition on micro-arc oxidation coatings on titanium for medical applications

A method of micro-arc oxidation (MAO) has been used for the obtaining of the bioactive calcium–phosphate coatings on the surface of nanostructured titanium. A homogeneous alkaline electrolyte containing phosphate ions and calcium (II) complexes with EDTA was used. An effect of changes of current modes on the coating characteristics has been studied. Obtained coatings have the molar ratio Ca/P up to 1.5 and include the phase of calcium phosphate β-Ca3(PO4)2. The adhesion strength of coatings to the titanium substrate is in the range 10–35 MPa, the thickness is up to 100 μm. The experiments in vivo have been carried out. They have shown 75% probability of new bone tissue growth on coatings with roughness of 2.5–5.5 μm.