Tas, A.C.

Article | 2007 | International Journal of Applied Ceramic Technology4 ( 2 ) , pp.152 - 163

Calcite (CaCO3) is a geologically abundant material, which can be used as a starting material in producing biomedical scaffolds for clinical dental and orthopedic applications. Bone-filling applications require porous, biocompatible, and resorbable materials. Commercially available CaCO3 powders were physically mixed, for 80-90 s, with an orthophosphoric acid (H3PO4) solution, which was partially neutralized to pH 3.2 by adding NaOH, to form biphasic, micro-, and macroporous calcite-apatitic calcium phosphate (Ap-CaP) cement scaffolds of low strength. The resultant carbonated and Na-doped Ap-CaP phase in these scaffolds crystallogra . . .phically and spectroscopically resembled calcium hydroxyapatite. Upon mixing CaCO3 powders and the setting solution, carbon dioxide gas was in situ generated and formed the pores. Thus formed scaffolds contained pores over the range of 20-750 µm. Scaffolds were also converted to single-phase Ap-CaP, without altering their porosity, by soaking them in 0.5 M phosphate buffer solutions at 80°C for 36 h in glass bottles. Soerensen's buffer solution was also shown to be able to convert the calcite powders into single-phase Ap-CaP powders upon soaking at 60-80°C. This robust procedure of synthesizing Ap-CaP bioceramics is simple and economical. © 2007 Blackwell Publishing Ltd Daha fazlası Daha az

Tas, A.C.

Article | 2009 | International Journal of Applied Ceramic Technology6 ( 1 ) , pp.53 - 59

Calcium carbonate particles with a unique tablet shape were produced by simply aging the prerefrigerated (at 4°C for 24h) CaCl2 -gelatin-urea solutions at 70°C for 24h in ordinary glass media bottles. Gelatin is known to be the denatured collagen. The thermal decomposition of dissolved urea was exploited to provide the Ca2+ ion and gelatin-containing solutions with aqueous carbonate ions. Monodisperse CaCO3 microtablets formed in solution had a mean particle size of 4 ± 2.5µm. CaCO3 microtablets were biphasic in nature and comprised of about 93% vaterite and 7% calcite. Identical solutions used without prerefrigeration yielded only . . .trigonal prismatic calcite crystals upon aging at 70°C for 24h. Prerefrigeration of CaCl2 -gelatin-urea solutions was thus shown to have a remarkable effect on the particle morphology. Samples were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and powder X-ray diffraction. © 2009 American Ceramic Society Daha fazlası Daha az