Effect of Fe2O3 content on the electrical resistivity of aluminous porcelain applied to electrical insulators

In general, the presence of Fe2O3 is claimed to reduce the insulating behavior of electrical porcelains, even if a rigorous proof has not yet been reported. The purpose of this study was to evaluate the real influence of Fe2O3 content on the electrical resistivity of a standard aluminous porcelain widely used in insulators. The electrical resistivity for the composition with 3 wt% Fe2O3 was higher than those found for standard aluminous porcelain, which was discussed in terms of the concentration of glassy and mullite phases. A reduction in the electrical resistivity was only observed in porcelain samples containing over 3 wt% Fe2O3. The presence of hematite phase was considered responsible for this reduction. These results suggest that low-cost raw materials with greater Fe2O3 content should not extensively affect the insulating properties and could therefore be used in manufacturing aluminous electrical porcelain.