Use Of Local Clays For The Production Of Porcelain Pin Insulators

ABSTRACT  

The use of local clays for the production of porcelain pin insulators was investigated. Clays from Awo-omama, Ibere and Nsu were used for the study. Test samples were made by varying the compositions of feldspar and quartz needed to form a mouldable plastic body with each clay. The following properties were determined: electrical resistivity, apparent porosity, water absorption, bulk density, linear shrinkage as well as crystalline phases produced after firing. This characterization was carried out for both the locally made porcelains and the standard. Results obtained showed that for the three clays studied, apparent porosity, water absorption and electrical resistivity increased with increase in the composition of the non-plastic materials (feldspar and quartz) while bulk density and linear shrinkage decreased with increase in non-plastic materials. The chemical composition of the clays (43.94-59.09%SiO2, 23.3427.75%Al2O3) compare well with values in literature (4060%Si2O, 25-45%Al2O3) for the production of ceramic refractories. Linear shrinkage values (7.27-9.68%), apparent porosity (14.0020.80%), water absorption (7.62-12.15%) are in conformity with standards     (7-10%, 16.45% and 8.20% respectively). Electrical resistivities recorded (0.61-1.39 x 107Ω-m) are in agreement with values obtained for standard (0.45 x 107Ω-m). These results are obtained in samples containing 50-70% clay, 20-30% feldspar and 10-20% quartz. It is therefore concluded that imported porcelains used by Power Holding Company of Nigeria (PHCN) can be replaced with porcelains made from these local clays.   

 Key Words: Porcelain, clay, feldspar, quartz, mullite, sintering, electrical resistivity