Porcelain insulator locally sourced materials Results and Discussion are introduced in this article from Linear Shrinkage, Water Absorption and Porosity, Bulk Density, and Failing Load, as well as the conclusion.
Porcelain insulator locally sourced materials Results and Discussion:
Table 3 shows the summary of the results obtained on the physical properties of the various specimens. The voltage and the corresponding resistance at which the materials demonstrate discontinuity are shown in Figure 1. The insulation resistance shown in Figure 2 reveals that at the injection of 1000 volts the porcelain samples show nearly the same resistance against the voltage injected. However, the insulation resistance was observed to generally decrease at higher values of voltage injected.
Installation resistance of insulator at various voltage injection
Physical properties variation with respect to kaolin and feldspar
Linear Shrinkage:
The total linear shrinkage percentage of porcelain insulators were found to increase with increasing kaolin content and reduction of feldspar as indicated by Tables 3, and Figure 2. This is characterized by the plastic nature of kaolin as a clay material. The shrinkage experienced was due to drying and firing of the insulators.
Water Absorption and Porosity:
There was a correlation between water absorption and porosity which were observed to decrease with increasing kaolin content and reduction of feldspar as indicated by Tables 3 and Figure 2. Feldspar as a flux, permit better flow of the mixture, it also allows for reaction with impurities to form slag which are burnt off at elevated temperatures during firing, hence creation of more porosity which automatically results in higher water absorption.
Bulk Density:
The bulk density experienced a general slight reduction with increasing amount of kaolin as feldspar was reducing as shown by Table 3 and Figure 2. This phenomenon was as a result of higher value of loss on ignition of kaolin (12.94) as against feldspar (0.22) given by the chemical analysis shown in Table 1.
Failing Load:
From Tables 3 and Figure 2, it was observed that as the percentage composition of kaolin increases while the percentage of feldspar reduces the strength of the insulator increases. This goes to show that porcelain strength are enhanced as kaolin content is increased and firing subsequently carried out.
Conclusion:
Good quality low voltage porcelain bodies were produced from kaolin clay, ball clay, feldspar and quartz. The sample 3 with composition of 33% Kaolin, 15% ball clay, 32% feldspar and 20% quartz was found to possess the highest failing load of 8.0 kN, corresponding to water absorption (1.55%), porosity (4.64%), bulk density (1.73 g/cm3), with appreciable insulation resistance of 6,630 Mega ohms at injection of 5,000 volts. Some constraints were encountered during firing which led to abnormality in the properties of some specimens produced and tested. Further work is recommended on the investigation of the internal structure of clay or porcelain particles, before and after firing to determine their effect on the physical, thermal and electrical properties of porcelain insulators.
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