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<p>Alkali-free SiO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub>-CaO-MgO with different SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> mass ratios was prepared by conventional melt quenching method. The glass network structure, thermodynamic properties and elastic modulus changes with SiO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub> ratios were investigated using various techniques. It is found that when SiO<sub>2</sub> is replaced by Al<sub>2</sub>O<sub>3</sub>, the Q<sup>4</sup> to Q<sup>3</sup> transition of silicon-oxygen network decreases while the aluminum-oxygen network increases, which result in the transformation of Si-O-Si bonds to Si-O-Al bonds and an increase in glass network connectivity even though the intermolecular bond strength decreases. The glass transition temperature (<i>T</i><sub>g</sub>) increases continuously, while the thermal expansion coefficient increases and high-temperature viscosity first decreases and then increases. Meanwhile, the elastic modulus values increase from 93 to 102 GPa. This indicates that the elastic modulus is mainly affected by packing factor and dissociation energy, and elements with higher packing factors and dissociation energies supplant those with lower values, resulting in increased rigidity within the glass.</p>

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Effects of SiO2/Al2O3 Ratios on Microstructure, Properties and Elastic Modulus of SiO2-Al2O3-CaO-MgO Alkali-Free Glass

  • 期刊论文

  • 发表日期：

    2026年1月6日

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  • Peng Dong,
  • Zhou Teng,
  • Jun Xie,
  • Jihong Zhang,
  • Dehua Xiong,
  • Dequan Chen

摘要

Alkali-free SiO2-Al2O3-CaO-MgO with different SiO2/Al2O3 mass ratios was prepared by conventional melt quenching method. The glass network structure, thermodynamic properties and elastic modulus changes with SiO2 and Al2O3 ratios were investigated using various techniques. It is found that when SiO2 is replaced by Al2O3, the Q4 to Q3 transition of silicon-oxygen network decreases while the aluminum-oxygen network increases, which result in the transformation of Si-O-Si bonds to Si-O-Al bonds and an increase in glass network connectivity even though the intermolecular bond strength decreases. The glass transition temperature (Tg) increases continuously, while the thermal expansion coefficient increases and high-temperature viscosity first decreases and then increases. Meanwhile, the elastic modulus values increase from 93 to 102 GPa. This indicates that the elastic modulus is mainly affected by packing factor and dissociation energy, and elements with higher packing factors and dissociation energies supplant those with lower values, resulting in increased rigidity within the glass.