DOLOMITE ADDITION IN NON-STOICHIOMETRIC CORDIERITE GLASS-CERAMIC: EFFECTS ON DIELECTRIC CONSTANT

Abstract

Glass-ceramic was successfully synthesis using glass route by dolomite addition in cordierite (MgO-SiO₂-Al₂O₃) using natural mineral kaolin and talc. The raw materials have been dictated due to their natural abundance (low price) and their beneficial properties. In this study, non-stoichiometric cordierite glass xCaO.(21-x)MgO.26Al₂O₃.53MgO was melt at 1540 °C followed by quenching process. The quenched glass was milled to < 3 µm and was used to prepare glass ceramic. The phase evolution and physical properties of the samples sintered at 980 °C for 2 hour was characterized. It is found that when dolomite addition (x < 3), the predominant phase in glass ceramics was found to be α-cordierite and the secondary crystalline phase to be forsterite. Anorthite start to appear when x = 5 and subsequently increased when x = 10. The dielectric constant of the samples increases by addition of dolomite. However, when x = 10, the dielectric constant decreases. The results shows that, a dense and low dielectric loss glass ceramic with predominant crystal phase of α-cordierite and some amount of anorthite was achieved using fine glass powders from talc and kaolin with an addition of dolomite.