Effects of Al2O3 addition on the phases, flow characteristics and morphology of the porous kaolin ceramics

Chen, Yung-Feng; Chang, Yu Huai; Wang, Moo–Chin; Hon, Min–Hsiung

doi:10.1016/j.msea.2004.01.036

Cited by 25 publications

(9 citation statements)

References 21 publications

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“…Kyanite crystallizes in triclinic system and starts decomposition only at temperature > 1100 °C. With the presence of both free silica and reactive Al 2 O 3 at high temperature, the formation of the acicular mullite is favored through atomic diffusion [11][12][13]. Additionally, the microstructural evolution of the kyanite during sintering is particular with the development of fibrous and acicular mullite between 1200 and 1350 °C far from the large size and elongated secondary mullite developed in the semi-vitrified matrix of porcelain considering the same range of temperature [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Semi-vitrified porous kyanite mullite ceramics: Young modulus, microstructure and pore size evolution

et al. 2019

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Microporous porcelain formulations are successfully carried out through sintering processing. During the thermal treatment of ceramic products, it was found that the addition of kyanite together with ϕand γ-Al 2 O 3 allowed to enhance interconnected pores network with micrometric size from 0.1 to 9 µm in a semi-vitrified composite. Between 1200 and 1350 °C, the mullitization of kyanite hindered the extension of vitrification and the growth of acicular mullite from the transformation of metakaolin. The main pores size decreased from 4.33 to 1.54 µm for the formulation containing 32 wt% of kyanite. In this interval the specific pore area increased from 0.64 to 8.75 m 2 g −1 due to the total conversion of the kyanite to fibrous and acicular mullite that reduced the voids provided by the earlier mullitization. The improvement in the mullitization without extensive vitrification and grain growth and the reduction of the pores size with the increase in the specific pore area contributed to the formation of a microporous matrix with the Young's modulus increased from 7 to > 20 GPa. The microstructure of the microporous porcelain, their specific pore area and pores size as well as the interconnection of pores was found innovative for the applications in the field of engineering filtration where high mechanical strength, strain, stiffness and pressure resistance are required.

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Section: Introductionmentioning

confidence: 99%

Semi-vitrified porous kyanite mullite ceramics: Young modulus, microstructure and pore size evolution

et al. 2019

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“…Formation of complete mullite occurred at 1550 °C. Chen et al [14] presented the effects of Al2O3 addition on the phases, flow characteristics and morphology of the porous kaolin ceramics, reported that the mullite content increases with increasing the sintering temperature, but it decreases with increasing the Al2O3 addition. Esharghawi et al [11] noted that the synthesis of pure and porous mullite has been shown to be possible by adding aluminium powder to kaolinitic clay before sintering in air.…”

Section: Introductionmentioning

confidence: 99%

Influence of heating rate and mechanical activation on the reaction between kaolin and aluminium powder

et al. 2018

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In this work, the effect of heating rate and mechanical activation on the reaction of kaolin and aluminium powder was investigated. A batch comprised of 89.5 wt% kaolin and 10.5 wt% aluminium powders was mixed and milled in a planetary ball-mill for 1, 5, 10, 20 and 40 h. The mixture powders were heat treated with a heating rate of 5, 10, 15, 20, 30 and 40 °C/min, respectively. After milling for 20 and 40 h, the results showed the formation of free silicon, quartz and nacrite (Al2Si2(OH)4) at room temperature. The kaolinite dehydroxylation, aluminium oxidation and the θto α-Al2O3 transformations are highly affected by heating rate and mechanical activation. As compared with the smallest heating rate, the mixtures heated with faster heating rate show the disappearance of the peak corresponding to the oxidation of aluminium and the appearance of a second peak corresponding to the formation of α-Al2O3. The intensity of the last peak increases with increasing of the heating rate and milled at lower milling time. The effects of heating rate in the reaction of kaolin and aluminium powder are attributed to the amorphization of kaolinite, the diffusion of Al 3+ to form an amorphous alumina layer on the particle surface and the generation of microcracks at the particle surface of aluminium powder.

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“…[1][2][3][4] Many methods have been made to fabricate porous mullite ceramics using different raw material, such as industrial grade and chemical method derived mullite. [5][6][7][8][9][10] Nevertheless, it is still necessary to develop new route in order to obtain porous mullite ceramics with desired structures and excellent performances.…”

Section: Introductionmentioning

confidence: 99%

Porous mullite ceramics fabricated by co-pyrolysis alumina powders filled silicone resin

Peng

Duan

et al. 2014

Materials Research Innovations

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Nanoporous mullite ceramics were fabricated by pyrolysis of micron alumina powders filled with silicone resin. The mixture of silicone resin and micron c-Al 2 O 3 began transforming to mullite at 1250uC in air, and could be entirely transformed to mullite when the pyrolysis temperature exceeded 1300uC. The effect of shaping pressure on microstructure and mechanical property of the porous mullite ceramics was investigated. The experimental results showed that the porosity and flexural strength can be easily tuned by changing shaping pressure. Both of the open porosity and average pores size of the obtained samples decreased at elevated shaping pressure. With a shaping pressure of 65 MPa, nanoporous mullite ceramics with an average pore size of 32 nm can be obtained, showing 23?5% in open porosity and 50 MPa in flexural strength. Interestingly, the microstructure of porous mullite ceramics consisted of loose region and dense region for the most possible reason that the Al 2 O 3 powders were un-homogeneously distributed in silicone resin.

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Effects of Al2O3 addition on the phases, flow characteristics and morphology of the porous kaolin ceramics

Cited by 25 publications

References 21 publications

Semi-vitrified porous kyanite mullite ceramics: Young modulus, microstructure and pore size evolution

Semi-vitrified porous kyanite mullite ceramics: Young modulus, microstructure and pore size evolution

Influence of heating rate and mechanical activation on the reaction between kaolin and aluminium powder

Porous mullite ceramics fabricated by co-pyrolysis alumina powders filled silicone resin

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