Production of glass-ceramic from high frequency induction melted cordierite glass

• We designed and made a cold crucible for glass melting.
• Electrical resistivity of non-stoichiometric cordierite glass was measured between 1100  °C to 1550  °C.
• Cordierite glass was melted using cold crucible induction melting at about 2200°C.
• The glass was nucleated and crystallized to make glass-ceramic.
• The effects of graphite starter and high temperature melting on the microstructure and crystal phases were reported.
• Induction melting was compared with conventional melting in an Alumina crucible.

Cold crucible induction melting (CCIM) is a special method which can be used for producing high temperature materials. In this research, a cordierite glass was melted by CCIM at approximately 2200 °C. For determining the temperature which the glass adsorbs the induction currents, the electrical resistivity of the glass was measured in the range of 1100 to 1550 °C. Nucleation and crystallization temperatures of the glasses were determined by differential thermal analysis (DTA) and their microstructures were evaluated by scanning electron microscopy (SEM). The mechanical strength was measured by using the 3-point bending strength test and the dielectric constants were measured in the 1–10 MHz frequency range. For comparison, all of the mentioned tests were applied to the melted glass in an alumina crucible. The temperature which the glass starts to absorb the induction currents was 1500 °C with the electrical resistivity of 10 Ω.cm. The glass transition and crystallization temperatures were different for the alumina and CCIM samples. The bending strength of the CCIM sample was higher than the alumina sample. Cordierite was the major phase in all samples. The dielectric constant of the CCIM sample was the same of the alumina crucible sample.