Influence of Fe2O3 content on the dielectric behavior of aluminous porcelain insulators

Abstract

Due to the increasing availability of substitute materials for electrical porcelain, research is needed to adapt formulations involving these materials to the current economic realities of the industry. This study assessed the effect of iron oxide concentration (0, 1, 2, 3, 5, and 8 wt%) on the dielectric properties of an aluminous porcelain composition commonly employed for electrical insulation based on different values of temperature and frequency. Samples with iron oxide contents of 0, 3, and 5 wt% were analyzed using dilatometry, X-ray diffraction, and scanning electron microscopy to evaluate the thermal, structural, and microstructural changes related to their Fe2O3 concentrations. Both the dielectric constant (epsilon(r)) and the loss tangent (tan delta) were measured and evaluated in every sample. Results indicated that the presence of Fe2O3 increased the dielectric constant and loss tangent, which could result in an increase in heating by dielectric losses. Fe2O3 contents of up to 5 wt% had no significant effect on the performance of these insulators at room temperature (similar to 30 degrees C) and a high frequency (1 MHz), especially when the hematite phase was completely solubilized in the porcelain phases. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.