Synthesis and mechanical properties of mullite from beach sand sillimanite: effect of TiO2

Tripathi, Himanshu; Banerjee, Goutam

doi:10.1016/s0955-2219(98)00149-6

Cited by 34 publications

(25 citation statements)

References 9 publications

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“…The presence of TiO 2 impurities in the kyanite can account for the resumption of shrinkage at higher temperatures, because this oxide favors the formation of a liquid at a temperature close to 1400°C. 20 The consequence is that it is possible to attain relative densities for kyanite-based ceramics in excess of 99% by relatively simple and inexpensive ceramic processing methods based on attrition milling.…”

Section: Discussionmentioning

confidence: 99%

Mechanical Activation of the Decomposition and Sintering of Kyanite

Aguilar-Santillan¹,

Cuenca-Álvarez²,

Balmori‐Ramírez³

et al. 2002

Journal of the American Ceramic Society

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The influence of attrition milling on the thermal decomposition of kyanite (Al2O3·SiO2) to mullite (3Al2O3·2SiO2) and SiO2, and its subsequent sintering, was studied. A commercial kyanite was attrition‐milled for times up to 12 h. Dilatometry confirmed that as‐received unmilled kyanite decomposes between 1300° and 1435°C. The decomposition reaction is slow initially and accelerates during the later stages until about one‐half of the decomposition occurs in the last 35°C. For the attrition‐milled kyanite, the onset decomposition temperature decreases, the transformation temperature interval is reduced, and both the decomposition reaction and subsequent sintering are accelerated. A dense microstructure of fine equiaxed mullite grains in the 1 μm size range, evenly dispersed in a glassy matrix, is obtained by sintering the attrition‐milled kyanites. These results are explained in terms of the energy accumulated during attrition milling, a reduction of the milled kyanite particle size, and the presence of a liquid phase during sintering.

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Section: Discussionmentioning

confidence: 99%

Mechanical Activation of the Decomposition and Sintering of Kyanite

Aguilar-Santillan¹,

Cuenca-Álvarez²,

Balmori‐Ramírez³

et al. 2002

Journal of the American Ceramic Society

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show abstract

“…TiO 2 , as a nucleating agent, facilitated the nucleation of acicular mullite, and its subsequent growth for promoting crystallization of secondary mullite in the porous mullite sintered bodies. According to the SiO 2 -Al 2 O 3 -TiO 2 ternary system phase diagram, titania entered into the liquid glassy phase at high temperatures when the total amount of titania (including existing titania in raw materials and added chemically pure titania) reached its solid-solution limit in mullite lattice [30][31][32]. Therefore, a low-viscosity titaniacontaining glassy liquid phase was formed, which accelerated the reaction diffusion between corundum and silica-rich glassy phase, as well as the precipitation of mullite crystals from transient liquid glassy phase.…”

Section: Xrd Patternsmentioning

confidence: 99%

Recycling of fly ash for preparing porous mullite membrane supports with titania addition

Dong

Hampshire

Zhou

et al. 2010

Journal of Hazardous Materials

101

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“…Since mullite is typically produced from cheap and naturally occurring raw materials, the level and types of impurity (i.e., TiO 2 , Fe 2 O 3, alkali/alkaline earth) also play an important role in its properties. For example, Fe 3+ and Ti 4+ can enter the mullite structure by substituting for Al 3+ at the octahedral site resulting in a reduction in its mechanical strength . In addition, alkali and alkaline earth elements can react with alumina and silica producing liquid phase at lower temperatures (1450‐1550°C compared to 1587°C in pure system) …”

Section: Introductionmentioning

confidence: 99%

“…For example, Fe 3+ and Ti 4+ can enter the mullite structure by substituting for Al 3+ at the octahedral site resulting in a reduction in its mechanical strength. [28][29][30][31] In addition, alkali and alkaline earth elements can react with alumina and silica producing liquid phase at lower temperatures (1450-1550°C compared to 1587°C in pure system). 32,33 Spark plasma sintering (SPS), unlike conventional firing processes, employs rapid heating rates (up to 1000°C/min) in vacuum (or inert atmosphere) under an applied pressure.…”

mentioning

confidence: 99%

Impact of spark plasma sintering (SPS) on mullite formation in porcelains

et al. 2017

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The effect of the spark plasma sintering (SPS) process on mullite formation in porcelains was studied using X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. SPS affected the kinetics and morphology of formed mullite. After sintering at 1100°C, unlike conventional sintering, SPS promoted the formation of mullite due to the combination of vacuum and applied pressure. Mullite crystal growth was altered by the atmosphere (vacuum), dwell time (0‐15 minutes), and temperature (1000‐1200°C). The applied pressure caused the mullite needles to orient perpendicular to the direction of the applied load. Depending on SPS dwell time, the mullite formed after sintering at 1100°C also had different crystal structure (tetragonal for short dwell time of 0‐5 minutes and orthorhombic for a long dwell time of 10‐15 minutes). Dissolution of mullite was observed at 1100°C by extending the dwell time by up to 15 minutes and the dissolved mullite reprecipitated on the small needles (~40 nm) and coarsened via Oswald ripening resulting in larger mullite needles (~60 nm).

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Synthesis and mechanical properties of mullite from beach sand sillimanite: effect of TiO2

Cited by 34 publications

References 9 publications

Mechanical Activation of the Decomposition and Sintering of Kyanite

Mechanical Activation of the Decomposition and Sintering of Kyanite

Recycling of fly ash for preparing porous mullite membrane supports with titania addition

Impact of spark plasma sintering (SPS) on mullite formation in porcelains

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