Biodegradable bi-layered coatings shaped by dipping of Ti films followed by the EPD of gelatin/hydroxyapatite composites

The work describes the incorporation of hydroxyapatite (HA) into gelatin (GN) films that gels on cooling shaped using electrophoretic deposition (EPD) on stainless steel substrates. Titanium buffer layer (Ti) prepared by dip coating was inserted to improve the bonding strength between HA/GN layer and substrate. Then suspensions composed of 1 vol% of HA/GN (76/24, 61/39, 50/50 wt/wt) were formulated to shape a bilayer structure Ti-HA/GN. Rheological properties of HA/GN suspensions, including the evolution of their viscoelastic behaviour at room conditions and at gelling temperature, were studied to determine the gel strength. Results demonstrate that the measurement of the suspension viscosity, its frequency dependent behaviour and the strength of its internal structure, are excellent tools to characterize slurry with regard to its suitability for shaping the polymer/ceramic composite by EPD. Obtained results confirmed the shaping of a bilayer system, growing by sequential dipping of Ti films and EPD of HA/GN coatings.