Rapid deposition of spherical apatite on alkali–heat treated titanium in modified simulated body fluid at high temperature

Abstract Biomimetic deposition in simulated body fluid (SBF) has been widely used to evaluate the bioactivity of implants and to prepare bioactive coatings. In this research, deposition of hydroxyapatite (HA) was studied during immersion in modified simulated body fluid (3 × SBF) at 57 °C of titanium samples heat-treated in alkaline solution (alkali–heat treatment, AH). SEM results show uniform large spherical agglomerates formed by soaking for only 1 day. In addition, the results of XRD and FTIR indicate that the coating consists of hydroxyapatite (HA) and brushite (CaHPO 4 ·2H 2 O). The large spherical apatite agglomerates were embedded into the whole deposited layer. High temperature and high concentration of SBF can greatly accelerate the deposition and increase the size of HA, even affect the morphology of deposited HA. In addition, the mechanical adhesive strength between the deposited coating and the substrate is relatively high, and slightly enhances with increasing immersion time.