Electrophoretic Deposition of 45S5 Bioglass(R) Coatings on the Ti6Al4V Prosthetic Alloy with Improved Mechanical Properties

In this paper, 45S5 Bioglass(R) coatings were elaborated by electrophoretic deposition (EPD) on the titanium alloy Ti6Al4V. An adequate grinding protocol was developed to obtain a stable suspension of submicrometric particles in isopropanol. The voltage and the deposition time of EPD were optimized. An optimal voltage of 30 V and two deposition times (30 and 90 s) were chosen to obtain two different coatings with thicknesses of 21 and 85 mu m, respectively. The as-deposited coatings were thermally treated following a two-step protocol: one hour at 120 degrees C followed by one hour at 450 degrees C. The surface morphology and the chemical analysis of the 45S5 Bioglass(R) coatings were assessed, before and after heat treatment, by scanning electron microscopy associated to X-ray microanalysis (SEM-EDXS). Their structural analysis was performed by X-ray diffraction (XRD). A scratch test study was developed for mechanical properties analysis. The obtained results revealed that the obtained coatings were homogeneous, weakly crystallized with an important compactness. An increase in the critical load L-C associated with the cohesive limit of the film (from Lc = 3.39 N to Lc = 5.18 N) was observed when the coating thickness was decreased from 85 to 21 mu m. After the thermal treatment, the chemical composition of the coatings was not altered, and their mechanical properties were improved.