Effect of Na2O Content on the Structure and Properties of LAS Glass-ceramics Prepared by Spodumene

The Li2O-Al2O3-SiO2 (LAS) glass-ceramics with low lithium content were prepared from spodumene mineral by melting method. XRD, DSC, and FTIR were used to study the crystallization process and structure of the samples. The results showed that the addition of Na2O promoted the precipitation of beta-quartz solid solution and its transformation to beta-spodumene solid solution. Mechanical performance tests and FESEM indicated that the larger grain size and inhomogeneous grain dispersion caused by the increase of Na2O content led to lower mechanical properties. In addition, low expansion glass-ceramics were prepared by an appropriate heat treatment according to DSC result, and when Na2O content was in the range of 1.22 wt% to 2.41 wt%, the average coefficient of thermal expansion (CTE) (30-300 degrees C) increased from -5.810x10(-7) to 5.322x10(-7)degrees C-1.