Fabrication and properties of mullite thermal insulation materials with in-situ synthesized mullite hollow whiskers

Liu, Hao; Xiong, Xiang; Li, Minghao; Wang, Zhoufu; Wang, Xitang; Ma, Yan; Yuan, Lin

doi:10.1016/j.ceramint.2020.02.245

Cited by 37 publications

(11 citation statements)

References 23 publications

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“…At the same time, there was a significant mass loss of about 6.4% before 500°C. An obvious exothermic peak near 1200°C could be explained by mullite formation, 38–40 and the mass loss at 500–1400°C was about 1.3%. With the continuous increase in temperature, weight of the samples remained stable, indicating that the ceramic samples exhibited excellent thermal stability 41 …”

Section: Resultsmentioning

confidence: 97%

High gas permeability and directional channels of mullite porous ceramics prepared by pectin‐based freeze‐drying method

Liu

Yuan

Tian

et al. 2023

Int J Applied Ceramic Tech

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New gel system for preparing mullite porous ceramics by gel‐casting freeze‐drying was proposed, using pectin as gel source and alumina and silica as raw materials. Directional channels were formed due to sublimation of water during freeze‐drying and decomposition of pectin during high temperature sintering to prepare porous mullite ceramic membranes. Effects of solid content on the properties of mullite ceramics in terms of phase composition, microstructure, apparent porosity, bulk density, pore size distribution, compressive strength, thermal conductivity, pressure drop, and gas permeability were investigated. It was found that prepared porous mullite possessed high apparent porosity (56.04%–75.34%), low bulk density (.77–1.37 g/cm3), uniform pore size distribution, relatively high compressive strength (.61–3.03 MPa), low thermal conductivity (.224–.329 W/(m·K)), high gas permeability coefficient (1.11 × 10−10–4.73 × 10−11 m2), and gas permeance (2.18 × 10−2–9.32 × 10−3 mol⋅m−2⋅s−1⋅Pa−1). These properties make prepared lightweight mullite ceramic membranes promising for application in high temperature flue gas filtration. Proposed gel system is expected to provide a new route to prepare porous ceramics with high porosity and directional channels.

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Section: Resultsmentioning

confidence: 97%

High gas permeability and directional channels of mullite porous ceramics prepared by pectin‐based freeze‐drying method

Liu

Yuan

Tian

et al. 2023

Int J Applied Ceramic Tech

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“…The possible reasons are high porosity and a certain amount of glass phase in these refractories. Mullite insulation material has low thermal conductivity (0.2 ∼ 0.4 W/(m K)) with excellent thermal insulation performance, but due to its poor mechanical properties (only 5 ∼ 10 MPa), its scope of application is limited [33,34]. In this work, although the thermal conductivity of the refractory materials was increased, but it is much lower than the theoretical thermal conductivity (3.98 W/(m K) at 1000°C).…”

Section: Discussionmentioning

confidence: 99%

Preparation of mullite refractories with low thermal conductivity and high strength

Sang

Wan

et al. 2023

Materials Science and Technology

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In the work, a novel mullite refractory was prepared by using coal gangue and low-grade raw bauxite as main raw materials, and the effect of the low-grade raw bauxite content and temperature on the microstructure and properties of mullite refractories was investigated. Both the green densities and cold compressive strength of mullite refractories increased with the increase of low-grade raw bauxite; also, the addition of low-grade raw bauxite had no significant effect on the thermal conductivity of such refractories treated at 1500°C. When the addition of low-grade raw bauxite was 34.5%, the compressive strength of the refractories treated at 1600°C was up to 104.3 MPa, and its thermal conductivity tested at 1000°C was only 1.02 W/(m K).

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“…Comportamentos semelhantes de transição morfológica foram observados por Liu et al (2020) ao estudar a fabricação de materiais de isolamento térmico de mulita, partindo de caulins comerciais.…”

Section: Caracterização Por Mevunclassified

Obtenção de mulita partindo de resíduo de caulim através de tratamento térmico em forno convencional

Silva

Chaves

Neves

et al. 2021

RSD

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Este trabalho teve como objetivo avaliar a capacidade de formação de mulita por meio de tratamento térmico aplicado em resíduo de caulim, em que foi investigada a influência da temperatura na formação desta fase. As amostras de resíduo de caulim e caulim comercial foram calcinadas a 1100 e 1200°C, com taxas de aquecimento de 2 e 30°C/min, para fins de comparação na obtenção da fase mulita, em forno convencional. Posteriormente, as amostras de partida e as tratadas termicamente foram caracterizadas por DRX, FTIR, MEV, EDX, TG/DTA, e quantificadas pelo método de Rietveld. Os resultados indicaram que as matérias primas são caulins de estruturas semelhantes, contendo como argilomineral predominante a caulinita, seguida de quartzo. Os eventos térmicos obtidos por TG/DTA evidenciaram nucleação de mulita em aproximadamente 903°C. O tratamento térmico aplicado favoreceu a formação das fases cristalinas: mulita (32 - 57%), seguida de quartzo (28 - 63%), uma componente amorfa rica em sílica (11 - 18% de fase vítrea) e, como fase minoritária, cristobalita (0,27 - 17%). As morfologias das amostras são de micro agulhas, com tamanhos e distribuição heterogêneas. O rejeito de caulim, comparado com o caulim comercial, apresentou potencial promissor como matéria prima para a obtenção da fase mulita. Esse contexto acarreta em ganhos econômicos e ambientais para a indústria cerâmica, uma vez que pode vir a substituir o caulim comercial na composição de massa para cerâmica branca, bem como reduzir a temperatura de sinterização devido à presença de fundentes como quartzo e feldspato.

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Fabrication and properties of mullite thermal insulation materials with in-situ synthesized mullite hollow whiskers

Cited by 37 publications

References 23 publications

High gas permeability and directional channels of mullite porous ceramics prepared by pectin‐based freeze‐drying method

High gas permeability and directional channels of mullite porous ceramics prepared by pectin‐based freeze‐drying method

Preparation of mullite refractories with low thermal conductivity and high strength

Obtenção de mulita partindo de resíduo de caulim através de tratamento térmico em forno convencional

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