The Influence of Suspension Properties on Electrophoretic Deposition of Hydroxyapatite Coatings

It is essential to study the crack controlling and deposition rate for the design and optimization of the coatings fabricated by the electrophoretic deposition(EPD) process.The property of the suspension is a key factor in the electrophoretic deposition of coatings.The parameters related to the property of the suspension such as particle size,zeta potential of the particle,conductivity and stability were characterized and then their effects on both the crack controlling and deposition rate in the electrophoretic deposition process of hydroxyapatite(HA) coatings were discussed.Results showed that the deposition rate increases at the first stage as the pH of the suspension increased and then decreased,gaining a maximum at the pH value of about 2.9.In addition,the aging time plays an important role in the deposition rate.Again,the pH of the suspension showed a significant influence on the crack controlling of HA coatings and cracks were minimized in the coating deposited from the suspension with a pH value of about 2.9.The suspension at pH 2.9 approximately with a conductivity of 11 μs/cm to 12 μs/cm and aging for 1 d to 2 d is appropriate for the electrophoretic deposition of needle-like HA coatings.