Electrophoretic deposition of carbon nanotube-reinforced hydroxyapatite bioactive layers on Ti–6Al–4V alloys for biomedical applications

Ultra-fine (20 nm) hydroxyapatite powders-reinforced with multi-walled carbon nanotubes were coated on Ti–6Al–4V medical alloy using electrophoretic deposition in an attempt to increase poor mechanical properties of hydroxyapatite, in particular inter-laminar shear strength between coating layer and implant surface. It is shown that the addition of carbon nanotubes increases both hardness, elastic modulus and inter-laminar shear strength of monolithic hydroxyapatite layers. A deposit thickness of 25 μm is also found to be critical for preventing crack formation during sintering.