Development of Electrical Porcelain Insulator from Locally Available Ceramic Raw Materials in Ethiopia.

Abstract

In this study three clay materials mined from Bombowha, Hosanna, Adamitulu and feldspar and quartz mined from Arero of Ethiopia were characterized to evaluate their potentials as raw materials for the production of quality electrical porcelain insulator. All samples collected from tabor ceramic share company ware oven dried at 1050C and pulverized, then the mineralogy, chemical composition, thermal property and plasticity of raw materials were characterized by using x-ray diffractometry (XRD), atomic absorption spectrometer (AAS), thermogravimetry analysis (DTA-TG) and Atterberg plasticity test respectively. Then five different porcelain insulator bodies were formulated based on raw materials chemical composition. By varying the proportion of selected clay, feldspar and quartz and fired at temperature of 1000 0C, 1100 0C, 1200 0C and 1300 0C separately. The fired product were analyzed with respect to, water absorbance, bulk density, and apparent porosity in accordance with ASTM standard, moreover the dielectric strength by measuring breakdown voltage and microstructure by XRD and SEM were analyzed. The results showed that Bombowha and Hosanna clays contain kaolinite as major mineral and contain 35.52wt% and 33.22wt% of Al2O3 respectively, but quartz is a predominant mineral in Adamitulu clay, it content 68.63wt% of SiO2. In other hand Arero feldspar has anorthoclase (Na, K)(Si3Al)O8 feldspar mineral with K2O+Na2O < 6.7wt%. And a formulated porcelain bodies consisting clay (40-50wt%), feldspar (40-50wt%) and quartz 10wt% yields a water absorbance (0.000%), apparent porosity (0.088 -0.141%), bulk density (2.463-2.5g/cm3), dielectric strength (6.53- 8kv/mm) at firing temperature 1300 0C and having a microstructure consisting of an optimum mullite and quartz crystals imbedded in sufficient glassy phase observed under XRD and SEM analysis. In conclusion the results of this study confirmed that locally available clay, quartz and feldspar have properties that can be potentially used to produce high quality electrical porcelain insulator in Ethiopia.