Hydroxyapatite formation on bioactive-glazed alumina

Alumina was coated with bioactive glass which is known to show a bonding behavior to living tissue. Another glass also coated between alumina and bioactive glass to compensate their differences in thermal expansion. After coating the alumina with bioactive glass, it reacted in simulated body fluids to investigate the formation of hydroxyapatite. The bioactive-glazed layer crystallized into α-wollastonite and β-wollastonite crystalline phases when the glaze was fired at 1200 °C and 1100 °C, respectively. When the samples reacted in SBF, α-wollastonite easily leached out of the surface and hydroxyapatite formed on the leached site. The leaching rate of α-wollastonite was faster than that of β-wollastonite, and the hydroxyapatite-forming rate was also faster in the sample containing α-wollastonite than in the other sample. No silica-rich layer was found underneath the newly developed hydroxyapatite.