Effect of nanosilica addition on the physicomechanical properties,pore morphology,and phase transformation of freeze cast hydroxyapatite scaffolds

Freeze casting technique is a simple and effective method for the fabrication of porous ceramic structures. The objective of this work is to study the production and characterization of hydroxyapatite/nanosilica (HA/nSiO₂) scaffolds fabricated through this method. In the experimental procedure, the solidified samples were prepared by slurries containing different concentration of HA and nSiO₂ followed by sintering procedure at 1200 and 1350 °C. The phase composition, microstructure, and compressive strength of the scaffolds were characterized by X-ray diffraction, scanning electron microscopy, and mechanical strength test. It was found that the porosity of the scaffolds was in the range of 30–86.5 % and the value of compressive strengths lied between 0.16 and 71.96 MPa which were influenced by nSiO₂ content, cooling rate, and sintering temperature. With respect to porosity, pore size, and compressive strength, the scaffolds with 5 % nSiO₂, the cooling rate of 1 °C/min and the sintering temperature of 1350 °C showed preferable results for bone tissue engineering applications.