The bio-eye porous hydroxyapatite (HAP) orbital implants are attracting considerable attention for the requirement of anophthalmus reconstruction. It is crucial to have the highly interconnected porous structure including appropriate macropores and micropores for improving the penetration and ingrowth of vascular orbital tissues. However, the mechanical strength of HAP to maintain the natural lid shape and prevent damage over time will decrease with the porosity increasing. Addressing this challenge, HAP with good mechanical performance for orbital implants were designed and prepared through a simple process. Hydroxyapatite powders with different particle sizes were synthesized by homogeneous precipitation method using commercially available calcium salt and phosphate salt as raw materials. The effects of addition method of reactants and pH value of system on morphology and composition of HAP powders were investigated. HAP powders were characterized by SEM, TEM, XRD, Raman spectrum and FT-IR. Uniform porous hydroxyapatite bulks were sintered at 1000℃ and fabricated using urea as pore generator and silica sol as binder. Detailed studies were performed to evaluate its structure, porosities, and mechanical properties, emphasizing the effect of different particles size of HAP and feeding content of urea. The results showed that the HAP microspheres with a diameter of 39?154 ?m and rod-shaped HAP powders with a diameter of 10?15 nm and a length of 24?36 nm were prepared. The as-prepared samples were hexagonal hydroxyapatite and had good crystallinity, due to the abundant phosphate and hydroxyl groups on the surface of powders, good biocompatibility can be expected. Nano-sized powders was helpful to the formation of porous bulks and the porosity was controlled by adjusting the amount of urea. The apparent porosity up to 69% and compressive strength reached 8 MPa when the mass ratio of HAP to urea was 1.5:1.
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