Effect of the content of Al2O3 on structure and properties of calcium-phosphate glasses: Two experimental case studies

Abstract

Two series of phosphate glasses [AC:xAl2O3-(35-x)CaO-65P2O5 and AP:xAl2O3-35CaO-(65-x) P2O5], including different contents of Al2O3, were prepared and the structure and properties were investigated. The structure of glasses were test by XRD and FTIR, and the thermal property were experiment by DSC. Density in room temperature of all the samples could be measured by Archimedes methods with deionized water. The chemical properties of glass were carried out in deionized water and alkaline water in 80°C. The surface of samples were investigated by SEM and the samples after corrosion were retest by XRD. XRD test shows that all the glass was amorphous and non-crystalline. Results from FTIR show that the Al2O3 in the glass can break the PO and the formation of new P-O-Al, which can make the glass structure more compact. Besides, the Al2O3 will take part in the glass structure mainly as the types of [AlO4] and [AlO6]. The glass transition temperature (Tg) and the crystallization temperature (Tc) approximately show an increased tendency, which is due to the glass structure becoming more compact. The density of AP and AC series glasses approximately shows a decreased tendency, which is attributable to the variation of the glass structure and the different values of molar mass. The weight loss of glasses shows a decreased tendency as the content of Al2O3 increases, the chemical properties can be significant improved. This result is due to the glass structure becoming more compact as the content of Al2O3 increases. The result of SEM and XRD shows that, and the CaO in the glass structure can form a thin film that can protect the glass from corrosion. In this two series of glass, AP4 glass has the best combination properties.