Mineralogical and dielectric properties of mullite and cordierite ceramics produced using wastes

Silva, Valmir José da; Almeida, Ester Pires de; Gonçalves, Wherllyson Patrício; Nóbrega, Raphael Borges da; Neves, G. A.; Lira, Hélio de Lucena; Menezes, Romualdo Rodrigues; Santana, Lisiane Navarro de Lima

doi:10.1016/j.ceramint.2018.11.161

Cited by 37 publications

(38 citation statements)

References 37 publications

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“…In general, by analyzing the porosity and frequency, lower dielectric constant values were observed for the most porous specimens when submitted to higher frequencies. This effect was due to the contribution of the pores to the value of dielectric constant; the air presents dielectric constant of ~1.0 [8], lower than those of the crystalline and amorphous phases present in the microstructure. The highest dielectric constant 100 kHz values at low frequencies were observed for samples A and C, which presented mullite and alumina as the main crystalline phases, behavior also observed by other researchers [4] who analyzed dielectric properties of mullite and alumina composites.…”

Section: Resultsmentioning

confidence: 99%

“…The electronic polarizations are oriented with the electric field in the lowfrequency range, but at a higher frequency, the individual internal dipoles that contribute to the dielectric constant cannot move instantaneously [26]. Some researchers [8] related the reduction of dielectric constant for mullite composites with the electronic polarization and accumulated energy in the interfaces of the phases present in the system. It was observed that the values of dielectric constant were lower for the samples fired at higher temperatures, behavior that was probably related to the phases and their quantities, as well as to the size of the grains.…”

Section: Resultsmentioning

confidence: 99%

“…For the substrate made with these materials, a signal delay can be diminished in very high-frequency communication systems [3]. Among the ceramic materials, mullite and mullite-based composites are highlighted in the electronic industry due to their low values of dielectric constant and loss tangent, as well as low coefficient of thermal expansion, being applied as electronic substrate, microelectronic packaging, electrical insulators and ceramic capacitors [4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Fabrication and characterization of dielectric ceramics using alumina and aluminosilicates

et al. 2020

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The aim was to study formulations containing aluminosilicate and alumina in order to obtain compositions with suitable properties to fabricate dielectric ceramic devices. Initially, the precursors were subjected to chemical, mineralogical and granulometric characterization. The formulations were defined and specimens were pressed (19.6 MPa) in shapes of disc and rectangular bar. Specimens were dried, heat-treated at 1400, 1450 and 1500 °C and the mineralogical, morphological, physical, dielectric and mechanical properties were evaluated. The relative dielectric constant (εr) and loss tangent (tanδ) were evaluated at 0.1, 1, 10 and 100 kHz at room temperature. The mullite was the major phase for the studied temperature range. Compositions with a higher content of fluxes showed lower porosity and better dielectric properties and flexural strength. Values of εr at 1 kHz (~3.5 to 4.5) were close to that of the mullite for the samples fired at 1400 °C.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fabrication and characterization of dielectric ceramics using alumina and aluminosilicates

et al. 2020

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“…Scanning electronic microscopy images (SEM) also showed that the microstructure of the ceramic formulation developed is similar to the standard ceramic mass. Silva et al [ 11 ] investigated the mineralogical, physical, and dielectric characteristics of the ceramic formulations contained industrial inorganic residues (kaolin and alumina), clay, and magnesium oxide. After sintering treatment (temperatures range between 950 °C and 1400 °C), the mullite and cordierite were the major mineralogical phases identified.…”

Section: Introductionmentioning

confidence: 99%

Development of Scheelite Tailings-Based Ceramic Formulations with the Potential to Manufacture Porcelain Tiles, Semi-Stoneware and Stoneware

et al. 2020

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New ceramic formulations based on scheelite tailing were developed, and their potential in the ceramic industry was evaluated. Green bodies with different contents of scheelite tailing (0–8 wt%) were sintered (1150 °C, 1200 °C, and 1250 °C) and characterized in terms of the main mineralogical phases, microstructure, and physico-mechanical properties. The mullite was the main phase identified in all sintered temperatures. This result was also ratified with the aid of scanning electron microscope (SEM) images, in which small needles of the mullite were detected. The presence of mullite is required because it contributes to increasing the mechanical resistance of the material. The physico-mechanical properties measured (water absorption, linear shrinkage, apparent porosity, and flexural strength) were compared to the ISO 13006, and the samples sintered at 1150 °C presented potential to be used as semi-stoneware, while those sintered at 1200 °C and 1250 °C can be employed stoneware and porcelain tiles, respectively.

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“…The ternary oxide system MgO‐Al 2 O 3 ‐SiO 2 (MAS) is characterized by two main minerals: cordierite (2MgO.2Al 2 O 3 .5SiO 2 ) and mullite (3Al 2 O 3 .2SiO 2 ), which have been the subject of several studies 1‐5 . However, in the MAS system, cordierite‐mullite composites attract much attention due to its: (i) high chemical and thermal stability; (ii) low expansion coefficient, conductivity, and dielectric constant; and (iii) excellent mechanical resistance at high temperature 4,6,7 . Thanks to these properties, they are widely used in various applications, such as: refractory materials, electrical porcelains, high temperature filtration applications (ie, as ceramic filters), and catalytic carriers 4,7 …”

Section: Introductionmentioning

confidence: 99%

Sintering and final properties of kaolinite‐magnesite tapes for the manufacture of cordierite‐mullite ceramics

Hammas

Lecomte‐Nana

Daou

et al. 2020

Int J Applied Ceramic Tech

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The present work aims at studying the effect of the sintering temperature and magnesite addition on the structure and final properties of silicate ceramics tapes. A kaolinitic clay from Algeria was selected and mixed with different magnesite contents (≤12 mass%). Tape casting process was used to produce the green tapes in an aqueous system with optimized amount of surfactants. The green tapes were fired from 1000°C to 1200°C using a dwelling time of 30 minutes. The effect of the dwelling time was investigated for a firing temperature of 1200°C namely: 30 minutes, 1 hour 30 minutes and 3 hours for samples with 6 and 12 mass% of magnesite. Regarding firing conditions, crystalline phases, thermal conductivity, porosity, and flexural strength were analyzed. The results showed that increasing the sintering temperature to 1200°C tended to significantly decrease the total porosity of samples, which led to the improvement of the stress to rupture values. Specimens with 6 and 12 mass% sintered during 3 hours exhibited highest stress to rupture values (≈117 MPa) and lowest thermal conductivity (<0.2 W.m−1.K−1) and moderate open porosity (27%). The as‐obtained ceramics appeared promising for further utilization in refractory industry, thanks to the presence of both cordierite and mullite phases.

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Mineralogical and dielectric properties of mullite and cordierite ceramics produced using wastes

Cited by 37 publications

References 37 publications

Fabrication and characterization of dielectric ceramics using alumina and aluminosilicates

Fabrication and characterization of dielectric ceramics using alumina and aluminosilicates

Development of Scheelite Tailings-Based Ceramic Formulations with the Potential to Manufacture Porcelain Tiles, Semi-Stoneware and Stoneware

Sintering and final properties of kaolinite‐magnesite tapes for the manufacture of cordierite‐mullite ceramics

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