Effect of B₂O₃ substitution for Al₂O₃ on the structure and properties of calcium aluminosilicate glass

Calcium aluminosilicate (CaO-Al₂O₃-SiO₂, CAS) glass, with varying B₂O₃ to Al₂O₃ substitutions, was prepared using the melting method. The network structure of this CAS glass was analyzed through Raman spectroscopy and nuclear magnetic resonance spectroscopy. The results showed as the B₂O₃ to Al₂O₃ substitution increased, the proportion of [BO₄] gradually decreased from 57.2 to 41.6%, while the proportion of [BO₃] increased from 42.8 to 58.4%. The primary form of Al³⁺ mainly exists in the glass network structure is [AlO₄]. The Qⁿ group is dominated by Q² (25.6 ~ 35.0%) units and Q³ (51.8 ~ 65.5%) units. As the B₂O₃ substitution for Al₂O₃ increased, there was a gradual decrease in Q¹ and Q² units, and a corresponding increase in Q³ units and Q⁴ units, leading to an increase in the degree of polymerization of glass network structure. However, the substitution also reduced the stability of the glass network structure. While the replacement of Al₂O₃ by B₂O₃ diminished the hardness, bending strength, expansion softening temperature and other properties of the glass, it significantly reduced the viscous activation energy, melting temperature, and forming temperature of the glass. These changes have significant implications for practical industrial production.