Mechanical and Dielectric Properties of High Temperature Coating Insulators Based on By-Product of Algerian Kaolin

Abstract

The main objective of this work is to study the mechanical and dielectric properties of high temperature coating insulators based on the by-product resulted from the raw kaolin treatment; this by-product represents about 21 wt% of the kaolin as commercial products. During sintering, the mineralogical phases are mainly mullite, quartz and vitreous silica besides rutile phase which is identified only at 1200 o and 1500 o C. The sample porosity decreases from 21% to 16%. Mechanical properties carried out by Young's modulus values are enhanced during calcinations from 54 to 57 GPa. Dielectric properties, in the frequency range of 10 5 -10 9 Hz, of the samples fired at 1400 o and 1500 o C show that they can be considered as insulators since they exhibit a high relative permittivity ( exp ) varying from 6.95 to 7.89 respectively. These parameters depend on glassy, quartz and mullite phases besides porous structures. Porosity affects considerably both the corrected relative permittivity ( c ) considering the large difference between  exp ,  c and the dielectric loss of the samples.

Study of the microstructure and mechanical properties of halloysite–kaolinite/BaCO3ceramic composites

“…4). The first endothermic peaks recorded at 494, 497 and 501°C for KB2, KB3 and KB4, respectively, are attributed to the dehydroxylation of kaolinite and halloysite (Bouzidi et al , 2014). In fact, with increasing amounts of BaCO 3 , the temperature of dehydroxylation decreased.…”

“…At temperatures >1200°C, the primary mullite crystals begin to grow by reacting with amorphous aluminosilicate phases, forming secondary mullite (mullite 3:2 or 3Al 2 O 3 •2SiO 2 ) (Ribeiro et al , 2005). Above 1100°C, the diffraction maxima of mullite appear, becoming more intense with increasing sintering temperature (Bouzidi et al , 2014).…”