Hydroxyapatite Formation on Cellular Alumina Coated with Bioactive Glasses

초록

In this study, we prepared cellular ceramics with high strength and high bioactivity. Cellular alumina was synthesized from poly-urethan sponge coated with alumina, and then the samples were coated by underglass to improve the mechanical strength and control the thermal expansion between cellular alumina and bioglass. In addition, the samples were coated by bioglass to characterize bioactivity. Poly-urethan sponge of 30ppi-size were wetted in alumina slurry and the samples were blowing with compressed-air for preparing cellular alumina without filling pores. And then, the samples were heat-treated varying temperature. In this way, alumina slurry was coated on the cellular alumina. With increasing the coating thickness of cellular alumina and varying heat treatment temperature, the compressive strength of the cellular alumina was measured. Also, the compressive strength of cellular alumina coated with glass was measured. The compressive strength of cellular alumina, which was heat-treated at 1550℃, was higher than that of the cellular alumina heat-treated at 1650℃ and 1400℃. The compressive strength of cellular alumina infiltrated with glass is higher approximately 3 times than that of the latter. The cellular alumina coated with bioactivity glass and heat-treated at 1100℃ was composed of α-wollastonite, β-wollastonite, and apatite, while the cellular alumina heat-treated at 1200℃ was crystallized into α-wollastonite and apatite. When heat-treated at 1100℃ hydroxyapatite was formed within 24hours in these cellular alumina reacted in SBF. On the contrary, When heat-treated at 1200℃ hydroxyapatite was formed with 18hours. Because capacity of Ca2+ ion released from α-wollastonite increased by heat-treatment at 1200℃. The hydroxyapatite was fastly formed.