Effect of firing temperature on triaxial electrical porcelain properties made from Tanzania locally sourced ceramic raw materials

Abstract

The study has investigated the effect of firing temperature during the production of technical triaxial electrical porcelain, for electrical insulation applications using Tanzania locally sourced ceramic raw materials. The green triaxial porcelain samples containing 50 wt% of Pugu kaolin, 35 wt% of Same clay and 15 wt% of feldspar were produced and fired at 1200°C-1300°C with a heating rate of 10°C/min (dwell time of 1.5h) and cooled at 10 0 C/min to a room temperature. X-ray diffraction technique was used to investigate phases developed in the triaxial electrical porcelain after firing process. The main crystalline phases revealed were mullite and quartz. The technological properties of the triaxial electrical porcelain such as water absorption, apparent porosity, bulk density, bending and dielectric strength were determined for each porcelain sample fired at high temperature. The optimum physical-mechanical and electrical properties were found at 1250 0 C. However, the triaxial electrical porcelain properties were found to decrease with the increase in firing temperature. Keywords: Firing temperature, triaxial electrical porcelain, physical-mechanical and dielectric properties Kulcsszavak: Égetési hőmérséklet, triaxiális szigetelő porcelán, fiziko-kémiai és dielektromos jellemzők Blasius NGAYAKAMO MSc Materials Scientist and Engineer at NM-AIST. Department of Materials Energy Science and Engineering. Fields of interest: ceramic raw materials, flux materials and high voltage porcelain insulators.

Fabrication of electrical porcelain insulator from ceramic raw materials of Oromia region, Ethiopia

“…6d, the dielectric strength of porcelain insulators were found to increase with increasing firing temperature and reaches a maximum of 8 kv/mm at a firing temperature of 1300 °C. The increasing of the dielectric strength may be due to increased vitrification range of the electrical porcelain samples at the optimized firing temperature (Ngayakamo and Park, 2018). Among the desired batch composition, the dielectric strength of batch-2, batch -3 and batch- 4 found to fall in the specified range of 6.1–13 kv/mm for porcelain insulator (Olupot et al., 2010).…”

“…The quality and quantity of the raw materials plays a significant role on the properties of blended green body and the fired body/microstructure of porcelain body that ultimately affect the performance of electrical porcelain insulators. The clay [Al 2 Si 2 O 5 (OH) 4 ] content when wet, acts as a binder for the other body ingredients in the green state which confirm plasticity of the body for easy molding and shaping, while feldspar [K x Na 1-x (AlSi 3 )O 8 ] serve as flux and alternative source of alumina and silica, whereas quartz (SiO 2 ) used as a filler material helps to maintain the shape of porcelain body at green state and during firing (Ngayakamo and Park, 2018). Various scholars designed efficient high quality porcelain insulator using ball clay as a plastic materials (Anih et al., 2005; Oladiji et al., 2010).…”

“…A crystalline alumino-silicate mullite (Al 6 Si 2 O 13 ) compound primary originated from clay relictcalled primary mullite and has a cuboidal structure under SEM analysis (Carty and Senapati, 1998; Iqbal and Lee, 2000; Lee and Iqbal, 2001; Lee et al., 2008). Whereas, the glassy phase or liquid phase originated during sintering of feldspar, causes densification of the ceramic bodies (Ngayakamo and Park, 2018). But an excess amount of glassy phase promotes free movement of ions in the porcelain bodies that result in poor electrical insulation.…”

Use of Firewood Ash Waste in Electrical Siliceous Porcelain

“…In fact, the siliceous porcelains with density values ranging from 2.20 to 2.40 g/cm 3 are appropriated to be used as low-voltage insulators 20,21 . The results also showed that the porcelain specimens with higher amount of firewood ash waste (4.20 wt.%) in the composition had lower apparent density, which may be due to the closed porosity caused by the formation of gas bubbles inside them [22][23][24] . This result indicates that the replacement of sodium feldspar with firewood ash waste in electrical siliceous porcelain formulations is limited.…”

Production of Electrical Porcelain Insulators from Local Raw Materials: A Review

“…This suggests that the possibility of electric shock is low since the insulator has a good charge storage capacity. The samples exhibit electrical resistance that are above the recommended range 1.0x10 6 which is a quality of a good insulator [3,54]. Generally, this suggests that the fine nature of the talc powder helped to amplify the qualities of the other constituents in the porcelain insulators.…”