TiO2 nanotube arrays induced deposition of hydroxyapatite coating by hydrothermal treatment

Abstract

In recent years, the bioactivity TiO2 nanotube arrays fabricated by anodization of Titanium has attracted wide attention. TiO2 nanotube arrays in the saturated Ca(OH)2 and 0.01 mol L−1 Na2HPO4 solution induced deposition of hydroxyapatite (HAp) coating were studied in this paper. The effect of the cooling time after hydrothermal treatment, hydrothermal temperature, Na2HPO4 solution concentration on the morphology of HAp coating induced by TiO2 nanotube arrays was investigated. The results show that the formed HAp coating is in a special two-layer structure at suitable hydrothermal temperature and Na2HPO4 solution concentration: the bottom layer is weakly crystallized HAp which is short rod-like in “criss-cross” spread, while the upper layer is HAp of high-degree crystallinity which is long rod-like in scattering spread. With the increase of cooling time after hydrothermal treatment, HAp coating coverage is increased with evener distribution and the long rod-like HAp crystal grains on the upper layer grow significantly. The increase in Na2HPO4 concentration makes the boundary between the two layers of the HAP coating unclear and gradually disappears. Too low hydrothermal temperature results in failure to form “cross” structured coating on the bottom layer.