In order to improve the bioactivity of NiTi alloys, which are being known as the suitable materials for biomedical
applications, numerous NiTi disks were electrophoretically coated by hetero-coagulated hydroxyapatite/
aluminum composite coatings in three main voltages from suspensions with different Al concentrations. In
this paper, the amount of Ni ions release and bioactivity of prepared samples as well as bonding strength of
the coating to substrate were investigated. The surface characterization of the coating by XRD, EDX, SEM, and
FTIR showed that HA particles bonded by Al particles. It caused the formation of a free crack coating on NiTi
disks. Moreover, the bonding strength of HA/Al coatings to NiTi substrate were improved by two times as compared to that of the pure HA coatings. Immersing of coated samples in SBF for 1 week showed that apatite formation ability was improved on HA/Al composite coating and Ni ions release from the surface of composite coating
decreased. These results induce the appropriate bioactivity and biocompatibility of the deposited HA/Al composite coatings on NiTi disks.