Effect of substituting Na2O with B2O3 on the crystallization and properties of MgO–Al2O3–SiO2 transparent glass-ceramics

MgO–Al2O3–SiO2 (MAS) transparent glass-ceramics were prepared with ZrO 2 as a nucleating agent, and the substitution of B 2 O 3 for Na 2 O on the properties of the MAS glass-ceramics was investigated systematically. The results show that the substitution of B 2 O 3 increased the glass transition temperature , crystallization temperature, and crystallization activation energy . Additionally, there was no change in the main crystal phase of the glass-ceramics, which were ZrO 2 (JCPDS PDF#.50-1089) and Al 0.52 Zr 0.48 O 1.74 (JCPDS PDF#.53-0294). The crystal growth mode shifted from three-dimensional growth to two-dimensional growth, and the crystal morphology transformed from a spherical appearance to a star-shaped appearance. Moreover, the mechanisms of the property changes induced by B 2 O 3 substitution are revealed and discussed. The transmittance of MAS glass-ceramics without B 2 O 3 decreased from 88 % to 32 % as the crystallization temperature increased from 800 °C to 920 °C, and decreased from 90 % to 8 % when B 2 O 3 was added. Additionally, the Vickers hardness of MAS glass-ceramics decreased from 6.37 GPa to 6.13 GPa, after the introduction of B 2 O 3 , while, the fracture toughness increased from 1.48 MPa m 1/2 to 1.55 MPa m 1/2 . The scratch behaviour of glass-ceramics exhibits a negative correlation with the applied load, but a positive correlation with the crystallization temperature. In particular, the incorporation of B 2 O 3 substantially enhances the scratch resistance of glass-ceramics. The conclusions provide researchers with the roles of B 2 O 3 in crystallization kinetics , microstructure, transmittance, and mechanical properties of MAS transparent glass-ceramics for various applications such as covers.