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This work presents a new experimental process for the thermal treatment of prosthetic coatings obtained by electrodeposition on titanium alloy Ti6Al4V. This thermal treatment is required to evaporate the solvent from the coating and to improve its cohesion and its adhesion to the titanium alloy substrate. When such treatment is carried out in air, the temperature is limited to 550°C due to the high oxidation of the titanium substrate. To overcome this limitation, we introduce a new thermal treatment process using a controlled atmosphere obtained by Argon injection under vacuum. In these conditions, the temperature can be increased up to 1 000°C. This process prevents the formation of the oxide layer onto the titanium alloy surface without noticeable modification of its mechanical properties. It also allows to obtain a fully crystallized biphasic coating made of hydroxyapatite and b-tricalcium phosphate. Consequently, this work resulted in obtaining an implant (calcium phosphate coating on Ti6Al4V) with improved mechanical properties.

Hydroxyapatite (HAP) and 58S Bioactive Glasses (BG) coatings are successfully synthesized by Electrophoretic Deposition (EPD) on Ti6Al4V alloy subjected to Surface Mechanical Attrition Treatment (SMAT). This process uses steel balls impacts on the Ti6Al4V surface to improve its mechanical properties. However when the Ti6Al4V substrate is treated by SMAT the industrial plasma spray technique is not efficient to obtain adherent HAP coatings. This problem is mainly related to the modifications of the Ti6Al4V surface topography due to the SMAT process. Therefore, in this work we demonstrate that EPD offers an efficient solution to solve this technical problem. Indeed we obtain a homogeneous and adherent HAP coating on the SMATed Ti6Al4V surface from a suspension of nanoparticles in ethanol. Moreover EPD is successfully employed to produce a 58S BG coating on the SMATed Ti6Al4V surface. Scanning Electron Microscopy (SEM) associated to Energy Dispersive X-Ray Spectroscopy (EDXS) reveals that the coatings obtained by EPD are adherent and compact without alteration of their chemical composition.