Journal of the American Ceramic Society, Vol.99, No.9, 2947-2955, 2016
Effect of Dispersants on the Electrophoretic Deposition of Hydroxyapatite-Carbon Nanotubes Nanocomposite Coatings
Isopropanolic Suspensions of HA nanoparticles (20 g/L) plus various concentrations of carbon nanotubes (CNTs) were prepared using Tris and triethanolamine as dispersant. The positively charged HA nanoparticles were heterocoagulated on the negatively charged CNTs and generated the HA-CNT composite particles with net positive surface charge. The heterocoagulation was more intensive in dispersant-containing suspensions (DCS) due to the higher zeta potential of HA nanoparticles in them. HA-CNTs particles can be rotated and aligned parallel to electric field as a result of torque exerted on them due to the generation of a dipole moment in CNTs during electrophoretic deposition (EPD). The mobility of HA-CNTs particles aligned parallel to electric field is similar to 50% higher than that of HA nanoparticles leading to the faster EPD from DCS when CNTs are added into them. CNTs more efficiently reinforced the coatings deposited from DCS due to the stronger electrostatic bonding between CNTs and HA nanoparticles in them.
Keywords:electrophoretic deposition;hydroxyapatite nanoparticles;carbon nanotubes;composite coatings;reinforcing