Mullite-based refractories fabricated by foam casting

Bartoníčková, Eva; Ptáček, Petr; Opravil, Tomáš; Šoukal, František; Másilko, Jiří; Novotný, Radoslav; Švec, Jiří; Havlica, Jaromír

doi:10.1016/j.ceramint.2015.07.032

Cited by 16 publications

(6 citation statements)

References 44 publications

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“…Um material cerâmico à base de mulita é um dos candidatos mais adequados para aplicações refratárias [16]. A refratariedade é a propriedade que o material tem de suportar altas temperaturas sem se deformar ou fundir.…”

Section: Introductionunclassified

Influência da composição e das variáveis de processamento deformulações à base de argilas - uso em materiais refratários

Figueiredo¹,

Fernandes²,

Silva³

et al. 2018

Cerâmica

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ResumoAs argilas são componentes fundamentais das massas para produção de materiais cerâmicos tradicionais, pois garantem plasticidade na etapa de conformação e resistência mecânica após a queima; também podem ser utilizadas nas formulações de cerâmicas refratárias devido ao desenvolvimento da fase mulita em temperaturas elevadas. O objetivo deste trabalho foi avaliar o efeito da composição, tempo de maturação e temperatura de queima em formulações à base de argilas para uso na fabricação de materiais refratários. As argilas foram caracterizadas por análise granulométrica, análise química, refratariedade, difração de raios X, análise térmica diferencial e termogravimétrica. As formulações contendo caulim mais ball clay e caulim mais esmectita foram submetidas à maturação por um período de 1 a 4 semanas. Em seguida, as massas foram conformadas por prensagem uniaxial obtendo-se corpos de prova, que foram submetidos a tratamento térmico em 1200, 1300 e 1400 °C, e, posteriormente, analisados quanto às propriedades: absorção de água, retração linear de queima e resistência à flexão em três pontos. Os resultados obtidos evidenciaram que as formulações em estudo apresentaram após queima fases de quartzo, cristobalita e mulita como fase majoritária. A temperatura de queima foi o parâmetro que apresentou maior influência nas propriedades avaliadas, com maior efeito da temperatura mais alta (1400 °C). Palavras-chave: argilas, composição, refratário. AbstractClays are key components of mass for traditional ceramic materials production because they ensure plasticity in the shaping step and mechanical resistance after firing. They can also be used in refractory ceramic formulations due to the development of mullite phase at high temperatures. The objective of this study was to evaluate the effect of composition, maturation time, and firing temperature on clay formulations for use in manufacturing refractory materials. The clays were characterized by particle size analysis, chemical analysis, refractoriness, X-ray diffraction, as well as differential thermal and thermogravimetric analyses. Formulations containing kaolin with ball clay and kaolin with smectite were submitted to a maturation period of 1 to 4 weeks. Next, the masses were shaped by uniaxial pressing to obtain test specimens, which were then subjected to heat treatment at 1200, 1300 and 1400 °C, and the following properties were subsequently analyzed: water absorption, linear firing shrinkage, and three-point flexural strength. The results showed that after firing the samples had quartz, cristobalite and mullite phases, with the latter as the major phase. The firing temperature was the parameter that had the greatest influence on the evaluated properties, with the highest temperature (1400 °C) exerting the most influence.

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Section: Introductionunclassified

Influência da composição e das variáveis de processamento deformulações à base de argilas - uso em materiais refratários

Figueiredo¹,

Fernandes²,

Silva³

et al. 2018

Cerâmica

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“…A considerable amount of mullite phase was observed in the sintered compositions at temperatures of 1300 and 1400ºC. According to Bartonickova et al 37 , the mullitebased ceramic is one of the most suitable candidates for refractory applications.…”

Section: Resultsmentioning

confidence: 99%

Influence of Processing Variables on Clay-Based Ceramic Formulations

et al. 2019

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The properties of ceramic materials and microstructural changes are dependent on the raw materials from which they are made and on the manner in which they are processed, from the composition to the established thermal treatment, heating rate, and firing temperature. In this study, the influence of some processing parameters (formulation, maturation time, and firing temperature) on the physical-mechanical properties and microstructural aspects of ceramic pieces produced from natural aluminosilicates was investigated. Because Brazil does not have many quality ball clays reserves, bentonite was included as a plasticizing agent in this study. The formulations were submitted to maturation for a period of one to four weeks and their characteristics were determined to evaluate plasticity. Following this, the specimens were extruded and subjected to heat at temperatures of 1200, 1300, and 1400ºC. The physical-mechanical properties determined were: water absorption, linear retraction, and flexural strength. Statistical analysis was applied. The results showed that, for the analyzed masses, neither the maturation time nor the physical and mechanical properties analyzed had influence on plasticity. The firing temperature was the factor that generated the greatest alteration in results, increasing the mechanical resistance and altering the size and interlocking of the mullite needles.

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“…However, mullite is an attractive engineering material as it has low thermal expansion and conductivity, high creep resistance, and corrosion stability together with suitable strength and fracture toughness, and is one of the crystalline phases most frequently found in the final phase composition of both traditional ceramics and new inorganic functional materials . The significant role of mullite in various materials has been reported in the large number of publications in recent years …”

Section: Introductionmentioning

confidence: 99%

“…[2][3][4][5][6][7][8] The significant role of mullite in various materials has been reported in the large number of publications in recent years. [9][10][11][12][13][14][15][16][17] Mullite whiskers, a special morphology of mullite crystal, have been considered as reinforcements in the high-temperature composites and porous ceramics for its excellent performance. 3,8,18,19 Various processing methods have been reported for preparing mullite whiskers.…”

Section: Introductionmentioning

confidence: 99%

Preparation of mullite whiskers from kaolin via the addition of tribasic calcium phosphate

Zhang

et al. 2017

Int J Applied Ceramic Tech

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Mullite whiskers are potential candidates for improving the mechanical and thermal properties of ceramic, glass, and composite material. In this work, well‐developed whisker‐shaped mullite has been produced by adding tribasic calcium phosphate (Ca3(PO4)2) into kaolin before calcining in air. In the raw kaolin, rod‐like mullite crystal of ~0.5‐1.0 μm length and ~0.05‐0.2 μm diameter formed at 1350°C, and mullite whiskers were not be observed; however, by doping 6 wt% Ca3(PO4)2 into kaolin, mullite whiskers of ~5.5 μm length and ~0.05‐0.10 μm diameter grew at 1250°C. The formation of high aspect ratio of mullite whiskers can probably be explained by the synergistic effect of P2O5 and CaO, resulting in the formation of liquid phase with a relatively higher content of Si and a lower viscosity at low temperature of 1250°C, which facilitates the growth of mullite displaying acicular morphology. The results are of interest in producing high aspect ratio of mullite whiskers from kaolin at reduced calcination temperatures.

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Mullite-based refractories fabricated by foam casting

Cited by 16 publications

References 44 publications

Influência da composição e das variáveis de processamento deformulações à base de argilas - uso em materiais refratários

Influência da composição e das variáveis de processamento deformulações à base de argilas - uso em materiais refratários

Influence of Processing Variables on Clay-Based Ceramic Formulations

Preparation of mullite whiskers from kaolin via the addition of tribasic calcium phosphate

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