CaO–MgO–SiO2 glass ceramics: Transferred arc plasma (TAP) synthesis and microstructural characterization

In this paper, synthesis of CaO–MgO–SiO2 glass ceramic using transferred arc plasma (TAP) processing method is illustrated. Homogeneous mixture of 51.6% SiO2, 35.6% CaO and 12.8% MgO prepared by dry mixing in a ball mill was kept in the anode well (which is the melting bed) of the 10 kW transferred arc plasma torch. It was melted in plasma at an operating power of 5 kW (by varying the processing time for 3, 5 and 8 min). The melt was cooled to solidify by applying forced air on it. The resulting samples were characterized for microstructure and phase composition. The phases were identified by scanning electron microscopy (SEM), using the back-scattered electron (BSE) image mode and X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). The microstructure was examined using optical microscopy (OM) and scanning electron microscopy. The micro-hardness, density and porosity measurements for the synthesized samples were carried out. Differential thermal analysis (DTA) was performed to study the thermal evolution. The results show the formation of diopside phase in the transferred arc plasma melted CaO–MgO–SiO2 glass ceramic system achieved with in a quite considerable short time of plasma processing. The method indicated that TAP technique could be a promising, time saving and one-step manufacturing process for the production of functional bulk glass ceramics.