Influence of alumina and silica addition on the physico-mechanical and dielectric behavior of ceramic porcelain insulator at high sintering temperature

Abstract

The high-strength electrical porcelain insulator plays a vital role in the power industry. The present study investigates the effect of alumina and silica addition on the physico-mechanical and electrical properties of porcelain bodies over high sintering temperatures. The pallets were prepared in different shapes and dimensions with the help of hydraulic press machine by pressing at 160 MPa for a period of 10-min. Different characterizations techniques such as; dilatometer, X-ray diffraction (XRD), and scanning electron microscopy (SEM) used to evaluate the thermal, structural, and microstructural changes, respectively by increasing the concentration of silica (0-20 wt.%) and decreasing alumina (45-25 wt.%) concentration for the base composition of porcelain insulator. The measurement of mechanical strength and physical behavior were analyzed for all the samples prepared with different compositions of alumina and silica with varying sintering temperature (1250 and 1350 °C). The sample with a composition having silica 10 wt.% of alumina 35 wt.% and sintered at 1350 °C, shows the maximum density of 2.55 g/cc with water absorption of 0.94%. This sample also shows the highest value of bending and compressive strength of 129 ± 5 and 202 ± 5 MPa respectively. The highest dielectric value of 5.75 and minimum dielectric loss of 0.05 at a frequency (2-20 GHz) is achieved for the same composition with silica 10 wt.% of alumina 35 wt.% sintered at 1350 °C. The composition having silica 10 wt.% with alumina 35 wt.% sintered at 1350 °C, has enormous potential to serve as a high strength refractory and a dielectric ceramic material for microwave applications.