Manufacture of porcelain insulators from locally available materials
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ORIGINAL PAPER
Manufacture of porcelain insulators from locally available materials C. S. Onodu1 · T. C. Madueme1 Received: 6 June 2019 / Accepted: 8 April 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract This study discusses the local production, electrical characteristics and performance in service of porcelain insulators for outdoor low-voltage apparatus. Concern was given to the identification, beneficiation, characterization and utilization of locally available raw materials in Nigeria for the production of electrical porcelain insulators, taking benefits of the availability of these raw materials. The process control presents figures, tables, simulations. The basic raw materials were separately prepared using a 200-μm sieve. The composition of the triaxial constituents was varied to produce samples for testing. Altering the percentage content of silica and the alumina recorded a change in the mechanical strength and the sintering temperature; this was handled by adding fluxes suitable for improving tensile strength without increasing sintering temperature of the paste. Porcelain slab samples of different triaxial composition were formed. Tests on mechanical resistance, porosity and water absorption were carried out. Sample A, with specific percentage composition of 38% feldspar, 18% quartz, 32% kaolin and 12% ball clay, was used to produce porcelain suitable for the 480 V pin insulators. The produced sample possess an electrical dielectric constant of 9.80, a dissipating factor of 0.060, flashover voltage of above 5 kV all at 50 Hz of supply voltage frequency and a mechanical load support of 13.85 kN. Keywords Benefication · Sintering · Characterization · Flashover · Mechanical load · Triaxial composition
1 Porcelain as electrical insulators Porcelains are primarily composed of clay, feldspar and a filler material, usually quartz or Alumina [1]. The clay [Al2 Si2 O5 (OH)4 ] gives plasticity to the ceramic mixture; flint or quartz (SiO2 ), maintains the shape of the formed article during firing, and feldspar [KX Na1−X (AlSi3 )O8 ] serves as flux [1, 2]. These three constituents place electrical porcelain in the phase system [(KNa)2 O–Al2 O3 SiO2 )] in terms of oxide constituents, hence the term triaxial porcelains [1]. The distinguishing factor in the properties of different porcelain products was brought about. For electric porcelains, the period of kiln work has been to increase mechanical strength. In most efforts to increase strength, emphasis has been placed on minimization of quartz in the porcelain formula because of the β to α phase inversion of quartz, which occurs at 573 °C
during cooling, by variations in the proportion of these materials, the processing and the firing schedule adopted.
2 Sources of materials in Nigeria This research work attempts to take a general over view of ceramic raw materials based on our field exploration and studio experimentation on these materials that were accessed for producing products that satisfy aesthetic, functional and technical purp
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