Electrophoretic deposition of porous CaO-MgO-SiO ₂ glass-ceramic coatings with B ₂O ₃ as additive on Ti-6Al-4V alloy

The sub-micron glass-ceramic powders in CaO-MgO-SiO ₂ system with 10 wt% B ₂O ₃ additive were synthesized by sol-gel process. Then bioactive porous CaO-MgO-SiO ₂ glass-ceramic coatings on Ti-6Al-4V alloy substrates were fabricated using electrophoretic deposition (EPD) technique. After being calcined at 850°C, the above coatings with thickness of 10-150 lm were uniform and crack-free, possessing porous structure with sub-micron and micron size connected pores. Ethanol was employed as the most suitable solvent to prepare the suspension for EPD. The coating porous appearance and porosity distribution could be controlled by adjusting the suspension concentration, applied voltage and deposition time. The heat-treated coatings possessed high crystalline and was mainly composed of diopside, akermanite, merwinite, calcium silicate and calcium borate silicate. Bonelike apatite was formed on the coatings after 7 days of soaking in simulated body fluid (SBF). The bonding strength of the coatings was needed to be further improved.