Ceramics-Silikáty 56 (4) 347-351 (2012)

Effect of different CaO/MgO ratios on the structural and mechanical properties of bioactive glass-ceramics

M. U. Hashmi, S. A. Shah, M. J. Zaidi, S. Alam

The aim of present work is to study the relationship between crystalline phases, microstructure and mechanical properties of bioactive glass-ceramics. For this purpose, glasses of composition (50-x) CaO–34SiO₂–14.5P₂O₅–1CaF₂–0.5MgF₂– xMgO (wt. %) (where x = 4, 25 and 46 respectively) were synthesized by conventional melt-quench method. Each glass was sintered according to the endothermal and exothermal peaks of differential scanning calorimetric (DSC) data to form three glass ceramics termed G1, G2 and G3 respectively. X-ray diffraction (XRD) revealed crystalline phases of hydroxyapatite and wollastonite in G1 and G2, whereas in G3, a new phase ‘whitlockite’ was observed probably due to a greater concentration of MgO in this sample. Bulk density of the samples was determined by Archimedes principle. Scanning electron microscope (SEM) data illustrated that the rate of densification of materials increased with the decrease of CaO/MgO ratio. Analysis of mechanical properties revealed that micro-hardness and bending strength of the samples increased with the increase in MgO content, which is in accordance with the results of XRD, SEM and bulk density.

Keywords: Melt-quench method, Crystalline phases, Densification, Hardness