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Andalusite

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Guihua Liao – 1st expert on this subject based on the ideXlab platform

  • preparation of Andalusite corundum kalsi2o6 material for the calcination of li ion battery cathode materials
    Journal of Alloys and Compounds, 2019
    Co-Authors: Dafei Ding, Guihua Liao, Liugang Chen, Lichun Zheng, Guotian Ye

    Abstract:

    Abstract The conventional refractory sagger materials, e.g., mullite, cordierite, and magnesium aluminum spinel, employed to calcine Li-ion battery (LIB) cathode materials, are easily attacked by the LIB material and thus have short lifetimes. To improve the corrosion resistances of refractory saggers to LIB materials, Andalusite–KAlSi2O6 (KAS4) materials with different contents of in-situ KAS4 were synthesized using Andalusite and KAS4 precursor calcined at 1300 °C. The microstructure evolution, phase development, corrosion resistances to Li(NixCoyMnz)O2 (LNCM) cathode materials and thermomechanical properties of the designed Andalusite-KAS4 materials were characterized. The results show that the corrosion resistances of the prepared Andalusite–KAS4 material were superior to those of the LNCM materials owing to the in–situ KAS4 wrapping Andalusite grains. The prepared Andalusite–corundum–KAS4 materials also exhibited improved strengths and appropriate thermal shock resistances compared with mullite-based refractories.

  • Andalusite transformation and properties of Andalusite bearing refractories fired in different atmospheres
    Ceramics International, 2019
    Co-Authors: Dafei Ding, Guihua Liao, Liugang Chen, Guotian Ye, Na Li, Xuekun Tian

    Abstract:

    Abstract We found in our research that Andalusite aggregate fired in a reducing atmosphere exhibits a lower mullitization rate than that fired in an air atmosphere. For investigating the effect of atmosphere on the transformation of Andalusite and the properties of Andalusite-containing refractories, Andalusite powder (≤0.074 mm) and refractories containing Andalusite aggregate (3–1 mm) were fired in air and carbon embedding, respectively. The phases and microstructure of the Andalusite fired in both atmospheres were characterized by X-ray diffraction and scanning electron microscopy, respectively. The correlations of the properties of the Andalusite-bearing refractories with the firing atmospheres were investigated in terms of volume stability, mechanical strength, and thermal shock resistance. The difference in the properties of the refractories was discussed with respect to the varied transformation rates of Andalusite, and in terms of the different viscosities of the silica-rich glass caused by the different atmospheres.

  • Densification behavior of mullite-Al2TiO5 composites by reaction sintering of natural Andalusite and TiO2
    Ceramics International, 2018
    Co-Authors: Liusheng Li, Guihua Liao, Qingfeng Wang, Kunpeng Li, Guotian Ye

    Abstract:

    Abstract In this work, mullite-Al2TiO5 composites were fabricated by natural Andalusite with TiO2 as an additive. The densification characteristic, phase composition and mullitization process of Andalusite with TiO2 addition was investigated by the Archimedes’ principle, dilatometry, X-ray diffraction and scanning electron microscopy (SEM-EDS) techniques. The results showed that the incorporation of TiO2 not only enhanced the thermal stability of in-situ Al2TiO5 in the silica liquid yielded from the mullitization of Andalusite, but also accelerated Andalusite decomposition and retarded mullite formation, which facilitated the sintering and densification of mullite-Al2TiO5 composites.

M Rigaud – 2nd expert on this subject based on the ideXlab platform

  • Andalusite‐Based High‐Alumina Castables
    Journal of the American Ceramic Society, 2004
    Co-Authors: L Rebouillat, M Rigaud

    Abstract:

    Andalusite is easily converted to mullite and silica on heating. A better understanding of the mullitization mechanisms provides new information on use of this mineral in refractory castables. By using specific particle-size distributions for Andalusite-based high-alumina castables, the primary mullite formation can be effectively enhanced by a secondary mullite reaction within castables matrices. The influence of ultrafine Andalusite grains on thermomechanical properties of specimens is underlined by testing hot modulus of rupture in combination with mineralogical and microscopic analyses. The results demonstrate that Andalusite has great promise as a component of high-alumina no-cement- or ultra-low-cement-containing castables.

  • Andalusite based high alumina castables
    Journal of the American Ceramic Society, 2004
    Co-Authors: L Rebouillat, M Rigaud

    Abstract:

    Andalusite is easily converted to mullite and silica on heating. A better understanding of the mullitization mechanisms provides new information on use of this mineral in refractory castables. By using specific particle-size distributions for Andalusite-based high-alumina castables, the primary mullite formation can be effectively enhanced by a secondary mullite reaction within castables matrices. The influence of ultrafine Andalusite grains on thermomechanical properties of specimens is underlined by testing hot modulus of rupture in combination with mineralogical and microscopic analyses. The results demonstrate that Andalusite has great promise as a component of high-alumina no-cement- or ultra-low-cement-containing castables.

  • Mullitization of Andalusite in bricks and castables
    UNIFIED INTERNATIONAL TECHNICAL CONFERENCE ON REFRACTORIES (UNITECR 97) VOL 1 – 3: 5TH BIENNIAL WORLDWIDE CONGRESS – REFRACTORIES A WORLDWIDE TECHNOLO, 1997
    Co-Authors: J P Ildefonse, V Gabis, M Rigaud, L Rebouillat, P Daniellou, Pascal Dubreuil

    Abstract:

    Observations on mullitized Andalusite in bricks and single crystals have\nrevealed that mullitization proceeds through a pseudormorphis, retaining\nthe grain form and bulk chemistry. Mullite is topotactically oriented in\nrelation with the Andalusite host crystal, the c-axis in both phases\nbeing parallel. The Andalusite monocrystal is transformed into a\ncomposite made of a 3:2 mullite monocrystal with a capillary network\nfilled with a silica-rich glass. The capillaries form highly\ninterconnected tubes with sections in the micrometer range and are\nelongated following the c-asis common to the neoformed mullite and the\nparent Andalusite. EDS chemical microanalysis show that this glass is\nsilica rich. It has been shown that near 80% of this glass remains\ntrapped in the capillary network of the neoformed mullite. Consequences\nof these findings have been tested reacting Andalusites of different\ngrain sizes with alumina powders, and are now put to use in the making\nof no-cement castable mises, with micronized Andalusite and hydratable\naluminas.

Jacques Poirier – 3rd expert on this subject based on the ideXlab platform

  • Andalusite an amazing refractory raw material with excellent corrosion resistance to sodium vapours
    Ceramics International, 2011
    Co-Authors: Jacques Poirier, P Prigent, M L Bouchetou

    Abstract:

    Abstract The chemical attack of alumina refractories by sodium vapours is far from been completely understood. In order to contribute to a better knowledge of this attack, a laboratory test was developed to simulate the sodium gaseous corrosion of different raw materials and refractories. Corrosion of alumina raw materials by sodium vapours is due to a dissolution–precipitation process by a Na 2 O rich liquid phase. The gaseous corrosion strongly depends on the microstructures and the assemblage of phases in alumina raw materials. Fire clay and Andalusite raw materials exhibit very high corrosion by Na vapours. In spite of an initial high silica glass content, and as a result of trapping of the main part of the glass in the capillary network of the mullite composite crystal, mullitised Andalusite leads to excellent corrosion resistance which is close to monocrystalline fused mullite. Consequently, The use of mullitised Andalusite particles in the matrix of alumina refractories limits the liquid phase formation during corrosion by sodium gas. These experimental results are in agreement with thermodynamic calculations.

  • the effect of the addition of fine Andalusite particles in refractory bricks on gaseous corrosion
    JOM, 2008
    Co-Authors: P Prigent, Marielaure Bouchetou, Jacques Poirier, P Hubert

    Abstract:

    In the past, the mechanisms of corrosion in refractory materials used in the flue wall of anode baking furnaces have been poorly understood. To better understand the processes of degradation, a study of corroded refractories from anode baking furnaces was conducted. This study found that all refractory bricks contain fine Andalusite particles in the matrix and fireclay as aggregates. The first stage of corrosion is the penetration of gaseous sodium, coming from recycled anodes, through the porosity of materials. Then, at high temperature, sodium becomes oxidized and is included in the liquid phase. The sodium-rich liquid phase corrodes the refractory material, in particular mullite networks. To understand why the Andalusite mineral is used in the refractory materials, a corrosion test able to simulate the gaseous corrosion of materials at laboratory scale was developed. Several recipes, composed of Andalusite or fireclay, were submitted to the corrosion test. The microstructural observations showed that the matrix is more sensitive to corrosion. Thus, the use of a raw material such as Andalusite in the matrix is advised in order to reduce the gaseous sodium corrosion of fireclay based bricks.

  • mullite grown from fired Andalusite grains the role of impurities and of the high temperature liquid phase on the kinetics of mullitization and consequences on thermal shocks resistance
    Ceramics International, 2005
    Co-Authors: Marielaure Bouchetou, J P Ildefonse, Jacques Poirier, Pierre Daniellou

    Abstract:

    Mullitization and microstructure of mullite grown from fired Andalusite grains has been studied in the literature. Mechanisms of mullite formation are well known: during heating, Andalusite single crystal grains are transformed into a composite made of a 3:2 mullite single crystal with a capillary network filled with silica rich liquid. But very few works studied the influence of the impurities on the kinetics of mullitization. This paper shows that the presence of impurities (mainly iron and alkalis) in the Andalusite increases the amount of the liquid phase and decreases the liquid viscosity. The mullitization kinetics depends on the Andalusite grain size, the chemical composition, the origin of the Andalusite deposit and the amount and the properties of the liquid phase. Because of the specific microstructure and the presence of the liquid phase, during thermal shocks in air, the mullitized Andalusite crystals exhibit a behaviour typical of composite materials: microcracks are deflected by mullite/glass interfaces and stopped in glass zones. During a further heating, cracks generated by a thermal shock are healed.