Study on Fabrication and Properties of Porous HA/SiO2Composite Coating on Titanium Substrate

Abstract

In order to obtain porous hydroxyapatite (HA) coating with high bonding strength to substrate, hydroxyapatite/silica/chitosan (HA/SiO2/CS) composite coatings were prepared on titanium substrate by electrophoretic deposition (EPD) in n-butylalcohol as dispersion medium and SiO2 powder as additive. And then a porous HA/SiO2 composite coating was obtained by sequentially sintering treatment. The surface morphology, chemical composition, phase composition and the bonding strength between composite coating and substrate were characterized by scanning electron microscopy (SEM), fourier transform infrared spec- trometer (FT-IR), X-ray diffraction (XRD) and shear strength testing experiment, respectively. The bioactiv- ity of the porous HA/SiO2 composite coating was evaluated by immersion in simulated body fluid (SBF). The results showed that the porous HA/SiO2 composite coating with uniform cavities was obtained by sin- tering at 700 ℃ from the HA/SiO2/CS composite coating fabricated by EPD in suspension with 1∶1∶1 mass ratio of HA/SiO2/CS. The large-pore diameter was about 10~15 μm, the small-pore diameter was about 1~5 μm, and the bonding strength between composite coating and substrate was up to 25.5 MPa. The coating surface was covered totally by carbonate-apatite after immersion in SBF for 7 d. This porous HA/SiO2 composite coating exhibits a good bioactivity and high bonding strength between composite coat- ing and substrate. Keywords hydroxyapatite; electrophoretic deposition; HA/SiO2 composite coating; porousity; bioactivity