Preparation of Low-Dielectric-Constant Kaolin Clay Ceramics by Chemical Cleaning Method

Abstract

Kaolin clay is an inexpensive and abundant material with potential for use as a low-dielectric-constant ceramic; however, the natural metallic oxides the clay contains hinder such applications. In this study, kaolin clay ceramics with excellent physical and dielectric properties were synthesized using kaolin clay as the raw material by chemical cleaning and sintering. Characterization of the resulting samples showed that the sulfuric acid treatment has a significant influence on the metallic oxide content and dielectric properties of the kaolin clay ceramics. When the kaolin clay raw material was treated with sulfuric acid three times, the dielectric constant decreased from 5.12 to 3.75 and the Vickers hardness increased from 946 to 1,214 kg/mm2 relative to the ceramic prepared from the untreated clay. Therefore, these ceramics exhibit significant potential for use in the microelectronics industry.

Characterization of Ceramic Membrane based on Calcium Carbonate from Onyx Stone and Its Application for Coconut Sap Treatment

“…Figure 1a presents the XRD patterns of the unsintered membrane sample and those sintered at 1200 o C. It reveals that the crystalline phases detected for the un-sintered sample (M1) consists of kaolin at 2θ = 20.9 o and 24.9 o [16][17][18], quartz, zeolite at 2θ = 27.2 o [19], and calcite (CaCO3) at 2θ = 30 o . In the sample sintered at 1200 o C (CM1), a zeolite crystal is formed followed by cristobalite, mullite (3Al2O32SiO2), and then by the crystallization of gehlenite (Ca2Al2SiO7).…”

“…Figure 1b presents the FTIR spectra of the sample sintered at 1200 o C. The absorption band of peak 1 at about 464 cm -1 is associated to tetrahedral Si-O bending vibrations, which is characteristic of the starting metakaoline [17]. The intensity decreases as the onyx stone content increases.…”

Applications of Clays in Nanocomposites and Ceramics

“…Clays and clay minerals have many industrial applications such as ceramics [12,13], paper coatings [14,15], pesticides [16], paints [17,18], pharmaceuticals [19,20], agriculture [21,22], construction industry [23], ion exchangers, separators, plastics [24][25][26], cosmetics [27], insulations [28], and electrical applications. Clay minerals can also be used as a good adsorbent for water purification due to lamellar structure, high cation exchange capacity, pore size distribution, and large surface area [29].…”