Effects of Sintering Temperature on Crystallization and Fabrication of Porous Bioactive Glass Scaffolds for Bone Regeneration

Abstract

<p>In this work the sintering ability of borosilicate (S53B50), borophosphate (P40B10) and phosphate (Sr) bioactive glasses was investigated. The glass powders were crushed and sintered in air at a heating rate of 10 °C/min for 2 hours at sintering temperatures between 480 °C-600 °C. The aim was to define the optimum sintering temperature prior to glass crystallization. The density of the samples was found to decrease when the temperature was increased up to 580 °C; probably due to the inhibition of the viscous flow of the particles during sintering thereby reducing the densification of the material. Such low porosity is not suitable in tissue engineering. To process highly porous scaffolds with porosity required for scaffold applicable to tissue engineering, the powders were further mixed with 60 vol.% and 70 vol.% of NH<sub>4</sub>(HCO<sub>3</sub>) foaming agent. Meanwhile, the density of the samples sintered with NH<sub>4</sub>(HCO<sub>3</sub>) was found to decrease with an increase in NH<sub>4</sub>(HCO<sub>3</sub>) content. This indicates an increase in porosity of the samples. The glass compositions reached an open porosity of more than 60% at the addition of 70 vol.% NH<sub>4</sub>(HCO<sub>3</sub>). In addition, SEM micrograph revealed large pores with good interconnection between the pores.</p>