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

Abstract

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 β-quartz solid solution and its transformation to β-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 °C) increased from −5.810×10⁻⁷ to 5.322×10⁻⁷°C⁻¹.

Keywords

low thermal expansion / Na₂O content / LAS glass-ceramics / spodumene