Hydroxyapatite Coatings on a 3D Porous Surface Using Thermal Substrate Method

Abstract

Hydroxyapatite (HAp) coated films were obtained using a thermal substrate method, whereby an aqueous solution at pH=7 or 8 containing Ca²⁺ and PO₄³⁻ ions was used to deposit a coating on porous-surfaces substrates formed by sintering 44–150 μm-sized Ti6Al4V powders on a solid commercially pure titanium (cpTi) base. The HAp coating conditions used were: coating time = ∼900 s and substrate temperature equal to 373 or 393 K. Coatings formed in a pH=7 solution at 373 K for 900 s and in a pH=8 solution at 393 K for 300 s showed that all of the surfaces of the Ti6Al4V sintered particles (both front and back faces) and the base cpTi substrate were covered with HAp, and that they maintained their original open-pored geometry. The precipitated HAp appeared to be denser on porous-surfaced samples compared with plain-surfaced cpTi samples. Use of the thermal substrate method with appropriate pH control, and substrate heating temperature and time was effective for forming HAp coatings on powder-sintered samples with a complex topography.