Microestrutura, fases cristalinas e propriedades elétricas de porcelanas aluminosas contendo diferentes concentrações de Fe2O3sinterizadas em atmosfera redutora e oxidante

Piva, D.H.; Piva, Roger Honorato; Venturini, Janio; Morelli, M. R.; Bergmann, Carlos Pérez

doi:10.1590/0366-69132015613591912

Cited by 3 publications

(3 citation statements)

References 19 publications

(26 reference statements)

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“…Portanto, quanto maior a solubilidade de impurezas na mulita mais acicular é o formato cristal. Em [43] ainda se relata que menores viscosidades da fase líquida aumentam a difusão das espécies envolvidas na cristalização da mulita e, consequentemente, atenuam o crescimento do Tabela VI -Ponto de fusão incongruente aproximado e cone pirométrico equivalente das massas cerâmicas formuladas.…”

Section: Caracterização Das Amostras Tratadas Termicamenteunclassified

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: Caracterização Das Amostras Tratadas Termicamenteunclassified

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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“…Therefore, the greater the solubility of impurities in mullite, the more acicular the crystal format will be. Piva et al 43 further report that lower viscosity of the liquid phase increases diffusion of the species involved in the crystallization of mullite and consequently attenuates the crystal growth. Chen et al 44 add that the continuous increase in grain size with increasing temperature indicates the possibility of transformation of primary mullite into secondary mullite.…”

Section: Resultsmentioning

confidence: 98%

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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“…This behavior occurs because generally, the presence of impurities (such as CaO present in the scheelite tailing) acts to reduce the temperature of formation of the metastable siliceous liquid, favoring mullitilization. The mullite crystal growth is probably attenuated in the C 0 sample due to a less viscous liquid phase, which does not favor the dissolution of silica and alumina [ 37 ]. Anorthite crystals were not observed because they have isometric round morphology with a size smaller than those of mullite [ 29 ] and probably are immersed in the vitreous phase.…”

Section: Resultsmentioning

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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Microestrutura, fases cristalinas e propriedades elétricas de porcelanas aluminosas contendo diferentes concentrações de Fe2O3sinterizadas em atmosfera redutora e oxidante

Cited by 3 publications

References 19 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

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

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