Evaluation and optimization of dielectric strength of porcelain insulators containing Cattle Bone Ash as a fluxing material

Abstract

Environmental pollution from cattle bones has been a major concern of recent. Cattle bones when calcinated at 700 °C decompose into lime (CaO) and β-tricalcium Phosphate [Ca 3 (PO 4 ) 2 ]. CaO has fluxing behavior similar to Na 2 O and K 2 O found in feldspar. This study aimed at investigating the dielectric and mechanical properties of porcelain insulators containing cattle bone ash (CBA) as a replacement for feldspar. CBA at 0 wt%, 5 wt%, 10 wt%, 20 wt% and 25 wt% were added. The samples were pressed at 40 MPa and fired at 1000-1250 °C. The microstructure and phase analysis of the samples was carried out using scanning electron microscope and X-ray diffraction method respectively. Response surface method (RSM) was used to optimize the dielectric strength of the samples. The results revealed that in samples with 25 wt% CBA, a maximum dielectric strength of 15 kV/mm was achieved at 1000 °C. However, in samples with 0 wt% CBA, a dielectric strength of 15 kV/mm was obtained at 1250 °C. In addition, the optimal dielectric strength of 13 kV/mm using RSM was achieved at 1040 °C. The results indicate that adding CBA lowers the firing temperature by approximately 250 °C. Firing temperature was when the dielectric strength was at maximum. The low firing temperature was attributed to the high content of CaO (71%) in CBA. In all the samples with CBA, the dielectric strength of 6-15 kV/mm achieved was within the specification for porcelain insulators. Therefore, CBA can be used to replace feldspar in the production of porcelain insulators.