Andalusite transformation and properties of andalusite-bearing refractories fired in different atmospheres

Ding, Dafei; Ye, Guotian; Li, Na; Liao, Guihua; Tian, Xuekun; Chen, Liugang

doi:10.1016/j.ceramint.2018.10.220

Cited by 15 publications

(8 citation statements)

References 14 publications

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“…The denser connection generated by silica-rich glass and secondary mullite between the aggregate and the matrix would also block oxygen diffusion [21], thereby promoting castable antioxidation. Figure 7 implies that the AP of the castable specimens F1-F4 is slightly lower than that of the castable sample M. It should be noted that, theoretically, the formation of mullite and secondary mullite would produce a volume expansion of approximately 3% and 8-10%, respectively [2,8,[15][16][17]. Due to these volume expansions, the AP in the castable should increase.…”

Section: Resultsmentioning

confidence: 92%

“…Materials 2020, 13, x FOR PEER REVIEW 7 of 10 Figure 7 implies that the AP of the castable specimens F1-F4 is slightly lower than that of the castable sample M. It should be noted that, theoretically, the formation of mullite and secondary mullite would produce a volume expansion of approximately 3% and 8-10%, respectively [2,8,[15][16][17]. Due to these volume expansions, the AP in the castable should increase.…”

Section: Resultsmentioning

confidence: 98%

“…Based on our previous study, adopting 19 wt% andalusite aggregates could significantly promote the antioxidation of ASC castables [8][9][10][11], as the high-temperature heating prompts the transformation of andalusite into mullite and silica-rich glass. This silica-rich glass obstructs the pore channels and impedes oxygen diffusion into the castable interior [15][16][17]. Furthermore, the exuded SiO 2 -rich glass from andalusite particles reacts with fine alumina to produce secondary mullite and raise the castable densification, thereby reducing the rate of oxygen diffusion into the castable interior and enhancing the oxidation resistance [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

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Enhancing the Oxidation Resistance of Al2O3-SiC-C Castables via Introducing Micronized Andalusite

Wang

et al. 2021

Materials

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Additions of andalusite aggregates (19 wt%) were shown in previous literature to enhance the antioxidation of Al2O3-SiC-C (ASC) castables. This work aims to investigate whether micronized andalusite has a greater influence on antioxidation improvement than andalusite aggregates. Various low contents (5 wt% and below) of micronized andalusite (≤5 μm) were introduced as a substitute for brown fused alumina in the matrix of ASC castables. The antioxidation of castable specimens was estimated by the oxidized area ratio on the fracture surface after a thermal shock test. The microstructure and phases of micronized andalusite and the castable specimens were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The results suggest that the antioxidation effects of ASC castables with a low addition of micronized andalusite are effectively enhanced. The heat-induced transformation of andalusite produces SiO2-rich glass, favoring the sintering of the castable matrix and impeding oxygen diffusion into the castable’s interior. Therefore, the castable antioxidation is enhanced without deteriorating the hot modulus of rupture.

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Enhancing the Oxidation Resistance of Al2O3-SiC-C Castables via Introducing Micronized Andalusite

Wang

et al. 2021

Materials

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“…The needle-like crystals were not seen in UF (Ar) and IL(Ar). In addition, Ding et al 49 reported that transformation of andalusite to mullite was depressed under the carbon-embedded conditions (reduction conditions), compared to air conditions. These are not contradicting with our results.…”

Section: Resultsmentioning

confidence: 99%

Analysis of Thermal Behavior of Crystalline Minerals in Bituminous Coal Samples under Air and Argon Atmospheres

et al. 2021

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The thermal behavior of ash components in two bituminous coal samples [Upper Freeport (the “UF”) and Illinois #6 (the “IL”)] was investigated under air and argon atmospheres in the temperature range of 800–1200 °C using thermal gravimetric–differential thermal analysis, X-ray diffraction transmission electron microscopy (TEM), and TEM–energy dispersive X-ray spectrometry measurements. The UF treated under air formed the needle-like crystals which were assumed to be mullite-related substances formed by transformation of andalusite, because the crystals are mainly composed of SiO2 and Al2O3. In contrast to the UF, the IL did not generate such crystals; however, when the IL was treated under air after carbonization under Ar, crystals appeared. The composition of the UF with an Al/Si ratio higher than that of the IL favored the formation of mullite-related substances, while the presence of lime in the IL inhibited the formation of mullite-related substances. Oldhamite was formed by the reaction of lime with sulfur at the carbonization of the IL under Ar and remained even at the successive air treatment. As lime was consumed, the formation of mullite-related substances was ceased to be inhibited under air after Ar treatment.

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“…This mineral is thermally unstable and transforms into 3-2 mullite and amorphous silica [12]. The great attention in andalusite is related to the fact that it is a suitable raw material to be employed in ceramics manufacturing including high-temperature applications such as refractory materials [1,13]. From the point of view of refractory applications, an extremely important phenomenon is the thermally activated transformation of andalusite into mullite.…”

Section: Introductionmentioning

confidence: 99%

Low‐temperature synthesis of mullite‐based ceramics from Moroccan naturally occurring andalusite and marble waste

Tabit

Borja

Saâdi

et al. 2021

Int J Applied Ceramic Tech

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The present work aims to prepare mullite-based ceramics at low temperature mainly from andalusite and marble byproduct by a solid-state interaction method. Marble powder byproduct was used, in the prospect of waste management, as a sintering aid. The influence of marble powder byproduct (5 wt.%) on the phase formation, microstructure-temperature evolution, densification, and mechanical strength was evaluated by means of XRD, TGA-DTA, and SEM. The results revealed that the andalusite remained present with mullite up to 1400 • C, while the addition of 5 wt.% of marble byproduct involved its complete transformation into mullite and a trace of anorthite. The transformation of andalusite into mullite upon the heating in the range 1300-1400 • C involved the densification of the matrix body and a significant increase in mechanical strength from 60 to 170 MPa, which promoted its application for refractory materials.

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Andalusite transformation and properties of andalusite-bearing refractories fired in different atmospheres

Cited by 15 publications

References 14 publications

Enhancing the Oxidation Resistance of Al2O3-SiC-C Castables via Introducing Micronized Andalusite

Enhancing the Oxidation Resistance of Al2O3-SiC-C Castables via Introducing Micronized Andalusite

Analysis of Thermal Behavior of Crystalline Minerals in Bituminous Coal Samples under Air and Argon Atmospheres

Low‐temperature synthesis of mullite‐based ceramics from Moroccan naturally occurring andalusite and marble waste

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