Sintering and dielectric properties of a technical porcelain prepared from economical natural raw materials

Abstract

In this study, the production of a technical porcelain, for the ceramic dielectric applications by using economical natural raw materials, was investigated. The basic porcelain composition was selected consisting of 30 wt% kaolin, 45 wt% potash-feldspar and 25 wt% quartz. The obtained phases in the sintered samples were investigated by X-ray diffraction, Fourier transform infrared spectroscopy analysis, and scanning electron microscopy images. It has been confirmed by these techniques that the main crystalline phases were quartz and mullite. Dielectric measurements of technical porcelains have been carried out at 1 kHz from room temperature to 200 °C. The dielectric constant, loss factor, dielectric loss tangent, and resistivity of the porcelain sample sintered at 1160 °C were 22-25, 0.32-1.80, 0.006-0.07, and 0.2-9 x 10 13 W.cm, respectively. The value of dielectric constant was significantly high when compared to that of conventional porcelains which did not exceed generally 9. ResumoNeste estudo, foi investigada a produção de uma porcelana técnica para aplicações cerâmicas dielétricas pelo uso de matériasprimas naturais de baixos custos. A composição básica da porcelana foi selecionada consistindo de 30% de caulim, 45% de feldspato potássico e 25% de quartzo. As fases obtidas nas amostras sinterizadas foram investigadas por difração de raios X, espectroscopia no infravermelho com transformada de Fourier e imagens de microscopia eletrônica de varredura. Foi confirmado por estas técnicas que as principais fases cristalinas foram quartzo e mulita. Medidas dielétricas das porcelanas técnicas foram realizadas a 1 kHz entre a temperatura ambiente de 200 °C. A constante dielétrica, fator de perda, tangente de perda dielétrica e resistividade da amostra de porcelana sinterizada a 1160 °C foram 22-25, 0,32-1,80, 0,006-0,07 e 0,2-9 x 10 13 .cm, respectivamente. O valor de constante dielétrica foi significativamente alto quando comparado ao de porcelanas convencionais que geralmente não excede 9. Palavras-chave: porcelana, caulim, feldspato, quartzo, sinterização, propriedades dielétricas.

Fabrication and characterization of dielectric ceramics using alumina and aluminosilicates

“…These two samples, which presented a higher Al 2 O 3 /SiO 2 ratio and smaller Fe 2 O 3 content, needed higher temperature (1500 °C) to increase the densification during the sintering process. For samples B and D, there was an increase in porosity when the specimens were fired at 1500 °C, the same behavior also observed by other researchers [2]. This effect may be related to the transformations and intensification of the formed phases; at this temperature, only the mullite phase was observed ( Fig.…”

“…The use of ceramic materials for electrical applications has motivated researches aiming to improve the performance of these materials and reducing costs in the manufacturing process [1]. The ceramics produced for electrical applications have excellent dielectric and thermal properties that favor the use in both electrical insulation, such as insulators and transformer bushings, and electronic devices such as capacitors, playing an important role in the electronics industry [2]. Ceramics with a low dielectric constant are of great importance for microwave integrated circuits.…”

Effect of cullet on firing temperature and dielectric properties of porcelain insulator

“…At the elevated temperature, a 1250 °C excess amount of low viscous glassy phase has formed and results in microstructure and crystalline phases change. Therefore it facilitates easy mobility of ions (Na + and K + ), which leads to decreasing dielectric strength at 1250 °C ( Figure 5 ) ( Kasrani et al., 2016 ). Besides, high concentrations of glassy phase in structure promote the releasing of trapped gasses, consequently yield new pore/void space in the porcelain that enhances conductivity.…”

Process and Development of Electrical Porcelain Insulator Using Edo State, Nigerian Raw Materials

“…Sample B3S had the highest density of 3.04 g/cm3, while sample A1S rated second highest value of 2.66 g/cm3. However, the bulk densities of all the samples produced are in the close range and are within the tolerable value for porcelain insulator compare with [23] since increase in temperature brings about decrease in bulk density. Table 4 revealed that only sample A1S met the required specification with compressive strength value of 25.67kN while others are below the recommended value.…”