SHEN Xuefeng, HE Xi, NING Tianxiang, LUO Zhiwei, LU Anxian
(School of Materials Science and Engineering, Central South University, Changsha 410083, Hunan, China)
Abstract: The P2O5-B2O3-Bi2O3 system based lead-free low-melting glasses were prepared by using the melting method. The effect of Al2O3 on structure and physicochemical properties of the glasses was studied. With increasing content of Al2O3, the form of Al2O3 in the glass was changed from [AlO4] tetrahedron to [AlO6] octahedron, while its effect on the formation of the glass network structure was varied from positive to negative. At the same time, the coefficient of thermal expansion was decreased first and then increased, whereas Tg and Tf were increased first and then decreased. The sample with 2 mol% Al2O3 exhibited the minimum thermal expansion coefficient of 9.298×10-6/℃, while the maximum values of Tg and Tf were 424 ℃ and 456 ℃, respectively. Both the density and molar volume of the glasses were not significantly altered, which were in the ranges of 6.34-6.38 g/cm3 and 41.30-41.60 cm3/mol respectively. The addition of 2 mol% Al2O3 could greatly improve the chemical stability of the glass without sacrificing the Vickers hardness.
Key words: Al2O3; low-melting point glass; network structure; physicochemical properties