Abstract:

Transparent Na₂O-ZnO-MgO-Al₂O₃-SiO₂ （NZMAS） glass-ceramics were prepared by a melting and heat treatment method. This study systematically investigated the effect of Na₂O content ranging from 0% to 10% （mole fraction） on the glass structure， crystallization behavior， and resultant properties. The results indicate that with increasing Na₂O content， both the glass transition temperature and crystallization temperature exhibit a decreasing trend. In samples with 0% and 2% Na₂O， the primary crystalline phases are MgAl₂Si₃O₁₀ and cordierite. When the Na₂O content reaches 4%， the MgAl₂Si₃O₁₀ phase disappears， and cordierite becomes the dominant phase. Further increasing the Na₂O content to 10% leads to the precipitation of the nepheline phase. For the base glass containing 8% Na₂O， heat-treated at 820 ℃ for 5 h （nucleation） followed by 970 ℃ for 1 h （crystallization）， the resulting glass-ceramics exhibit uniformly distributed fine crystals with an average grain size of approximately 105.9 nm and a visible light transmittance of up to ~80%. It exhibits high Vickers hardness and flexural strength， measuring 7.31 GPa and 134 MPa， respectively. After undergoing ion exchange in a pure KNO₃ salt bath at 460 ℃ for 4 h， this sample achieves a Vickers hardness of 7.81 GPa and a flexural strength of 375 MPa.This research demonstrates that the developed glass-ceramics possess a combination of excellent optical and mechanical properties， showing promising application potential in fields such as mobile terminal cover glass.

Key words: transparent glass-ceramics, cordierite, chemical strengthening, Vickers hardness, flexural strength