In situ spinel bonded refractory castable in relation to co-precipitation and sol–gel derived spinel forming agents

Mukhopadhyay, Siddhartha; Sen, Sandipan; Maiti, Tanmoy; Mukherjee, M.; Nandy, R.N.; Sinhamahapatra, B.K.

doi:10.1016/s0272-8842(03)00028-2

Cited by 23 publications

(13 citation statements)

References 18 publications

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“…Calcium aluminate powders prepared by chemical processing techniques proved to be X-ray amorphous and of high surface area when calcined at low temperatures. 14 Parr 15 prepared CaAl 2 O 4 by evaporative decomposition of a solution made from calcium and aluminum nitrate precursors. After heat treatment at 900°C for less than 1 h, crystalline CaAl 2 O 4 was obtained.…”

Section: Introductionmentioning

confidence: 99%

Low Temperature Synthesis of High Alumina Cements by Gel‐Trapped Co‐Precipitation Process and Their Implementation as Castables

et al. 2012

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Use of high alumina cement (HAC) as low cement castables (LCC) and ultra-cement castables (ULCC) has increased for refractories applications over the last few years. HAC is being prepared commercially, by fusing or sintering a mixture of argillaceous and calcareous materials above 1500°C and subsequent grinding to obtain a fine powder. Powders produced by this method have low specific surface area. Therefore, the present work was aimed to prepare nano structured HAC powders at lower temperatures than the conventional one. The powder process adopted here was modified gel-trapped precipitation method as described earlier. Two compositions of calcium aluminate powders containing 70 and 80 wt% Al 2 O 3 , respectively, were selected. The remaining material was CaO in both mixtures. The gel powders obtained by the abovementioned process were calcined at different temperatures with varying soaking periods. The prepared cements were characterized for structural, mechanical, and cementing properties. Finally, the calcination temperature and time were optimized to obtain the desired phases in HAC. The prime cementing phases observed were CA, CA 2 , CA 6 , C 3 A 5 , and C 4 A 3 SO 4 . These cements were then used with bauxite of different grain sizes to prepare LCC and then their physical properties were studied. The XRD patterns of the bauxite-based castables indicated the formation of the corundum phase along with a mullite phase in all samples. Castable containing HAC and 10 wt% zirconia substituted for bauxite improved physico-mechanical and refractory properties. Mullite formed at high temperature acts as a bonding phase and is accounted for high CCS values. These excellent properties of such castables may enable their use in various applications such as refractory lining for fabrication of steel, aluminum,

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Section: Introductionmentioning

confidence: 99%

Low Temperature Synthesis of High Alumina Cements by Gel‐Trapped Co‐Precipitation Process and Their Implementation as Castables

et al. 2012

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“…However, this process is associated with excessive volume expansion, dusting, and hydration problem during fabrication with the appearance of dawsonite and hydrotalcite phases. During the last few decades, a variety of new techniques have been used to prepare MgAl 2 O 4 spinel, for example, hydrothermal synthesis, coprecipitation, plasma spray decomposition, sol‐gel methods, freeze drying and decomposition of organometallic compounds etc . In these processes, good quality of the spinel product is expected primarily due to the purity of the precursor materials used and chemical homogeneity obtained from the synthesis route .…”

Section: Introductionmentioning

confidence: 99%

“…During the last few decades, a variety of new techniques have been used to prepare MgAl 2 O 4 spinel, for example, hydrothermal synthesis, coprecipitation, plasma spray decomposition, sol‐gel methods, freeze drying and decomposition of organometallic compounds etc . In these processes, good quality of the spinel product is expected primarily due to the purity of the precursor materials used and chemical homogeneity obtained from the synthesis route . Sol‐gel technique is a successful route for spinel production in terms of purity, homogeneity, and relatively lower formation temperature …”

Section: Introductionmentioning

confidence: 99%

Improvement of Mullite and Magnesia‐Based Refractory Castables Through Addition of Nano‐Spinel Powder

Khalil

Wahsh

Ewais

et al. 2012

Int J Applied Ceramic Tech

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Two different commercial refractory castables based on mullite or magnesia aggregates have been improved through addition of 0-25 wt.% nano-magnesium aluminate spinel (MA) powder. Physico-mechanical and refractory properties were tested at different firing temperatures. The phase composition, thermal analysis, and microstructure of these refractory castables were detected using X-ray diffraction (XRD), differential thermal analysis (DTA), as well as scanning electron microscope (SEM) attached with energy dispersive X-ray unit, respectively. The castable sample mix containing 10 wt.% nano-MA spinel powder was chosen as an optimum composition according to its good sintering, mechanical as well as refractory properties. *nagy2071@yahoo.com

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“…MAspinel is now extensively applied in high performance refractory castables. The conventional method of the preparation of MA-spinel is solid state sintering between high purity MgO and Al 2 O 3 where the temperature needed is normally between 1200 and 1400 8C for commercial practice [6,7]. The self-forming (in situ) spinel is fabricated during service by reaction of fine magnesia (MgO) additions with alumina present in the matrix (bond) fines, often in the calcium aluminate cement.…”

Section: Introductionmentioning

confidence: 99%

Phase composition of bauxite-based refractory castables

Abou-Sekkina

Abo-El-Enein

Khalil

et al. 2011

Ceramics International

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In situ spinel bonded refractory castable in relation to co-precipitation and sol–gel derived spinel forming agents

Cited by 23 publications

References 18 publications

Low Temperature Synthesis of High Alumina Cements by Gel‐Trapped Co‐Precipitation Process and Their Implementation as Castables

Low Temperature Synthesis of High Alumina Cements by Gel‐Trapped Co‐Precipitation Process and Their Implementation as Castables

Improvement of Mullite and Magnesia‐Based Refractory Castables Through Addition of Nano‐Spinel Powder

Phase composition of bauxite-based refractory castables

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