Abstract: Transparent lithium aluminum silicon glass-ceramics with different Na₂O content was prepared by melting method, and the effect of different Na₂O content on the crystallization and properties of the glass were studied by DSC, XRD, FESEM and other test methods. The results show that the introduction of Na₂O can significantly reduce the transition temperature and crystallization temperature of glass, and inhibit the precipitation of LiAlSi₄O₁₀ crystalline phase. However, the introduction of Na₂O leads to the precipitation of a new Li₂Si₂O₅ phase in glass-ceramics, and with the increase of Na₂O content, Li₂Si₂O₅ transforms into the main crystal phase. Since the crystal size is in the nanometer range, the change of main crystal phase has little effect on transmittance, and the visible light transmittance of glass-ceramics is higher than 85%. The transition of main crystal phase significantly enhances the mechanical properties of glass-ceramics, and the flexural strength increases from 300 MPa to 331 MPa. The introduction of Na₂O effectively enhances the Na-K exchange. When the LAS glass-ceramics with Na₂O content of 4% (mass fraction) exchanges in KNO₃ molten salt at 410 ℃ for 6 h, the Vickers hardness increases from 7.108 GPa to 7.403 GPa, and the flexural strength increases from 331 MPa to 470 MPa.

Key words: Na₂O, LiAlSi₄O₁₀, Li₂Si₂O₅, Li₂O-Al₂O₃-SiO₂ glass-ceramics, main crystal phase transition, Na-K exchange