Comparison of hydroxyapatite ceramics and hydroxyapatite/borosilicate glass composites prepared by slip casting

Borosilicate glass powder with a softening point of 821 °C was prepared by crushing Pyrex® borosilicate glass fragments. Hydroxyapatite (HA) ceramics and HA/borosilicate glass (50 wt.%) composites were prepared by slip casting. The influence of borosilicate glass on the densification and phase change of hydroxyapatite was studied over sintering temperatures from 500 to 1200 °C. It was found that the borosilicate glass inhibited the decomposition of HA phase and enhanced the densification of the composites. When the sintering temperature was higher than 1100 °C, the glass liquid flowed away from the sample surface and was trapped inside the sample, leading to a structure of a relatively strong and dense HA/glass core and a bioactive and porous HA surface layer.