Effect of Surface Topography and Chemical Composition on Wettability of Calcium Phosphate Coatings Formed on Ti-40Nb Alloy

The influence of the microarc oxidation parameters as electrical voltage and process duration on the surface morphology and topography, wettability and chemical composition of calcium phosphate coatings on the low elastic module Ti-40mas.%Nb (Ti-40Nb) alloy surface has been investigated. The linear growth of thickness and roughness and the linear decrease of the free surface energy with increasing process electrical voltage have been obtained. It was shown that calcium phosphate coatings have low contact angle with liquids and high free surface energy, as a consequence. It indicates a high hydrophilicity. X-ray diffraction analyses showed that the coatings after deposition have X-ray amorphous state that indicates high rate of coating dissolution. The coatings have maximum Ca/P ratio is 0.6. The optimal range of the oxidation voltage from 200 to 250 V and process duration from 5 to 10 min has been found. Such parameters allow to form the coating with the specific morphology, roughness and thickness and high hydrophylicity.