Microstructure and phase evolution of alumina–spinel self-flowing refractory castables containing nano-alumina particles

Otroj, Sasan; Daghighi, Arash

doi:10.1016/j.ceramint.2010.11.013

Cited by 34 publications

(33 citation statements)

References 15 publications

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“…It is easy to understand that because of dehydration of binders, the bulk densities of all the specimens declined, while the apparent porosities increased gradually during the period of 110–1000°C. Compared with the period of 110–1000°C, specimen becomes much looser during the period of 1000–1500°C, and this should be considered as the result of the volume expansion caused by the formation of CA 6 in the matrix with the addition of AR78 and AR90 and by the formation of secondary spinel of sample with the addition of MR66 …”

Section: Resultsmentioning

confidence: 99%

“…Compared with the period of 110-1000°C, specimen becomes www.ceramics.org/ACT Effect of Spinel Kinds on Castables Properties much looser during the period of 1000-1500°C, and this should be considered as the result of the volume expansion caused by the formation of CA 6 in the matrix with the addition of AR78 and AR90 and by the formation of secondary spinel of sample with the addition of MR66. 16 The CMOR and CCS of three different test castables after curing at 20°C for 24, drying at 110°C for 24 h, firing at 1000 and 1500°C, respectively, are given in Figs 5 and 6. It can be seen that CMOR and CCS of the specimens with the addition of various spinel present the same changing tendency as the temperature increases, and the maximum CMOR and CCS are obtained after firing at 1500°C, following drying at 110°C, and the minimum CMOR and CCS are obtained after curing at 20°C.…”

Section: Resultsmentioning

confidence: 99%

“…This is very much desirable for steel ladles where the refractory lining has to withstand aggressive operational atmosphere of secondary refining process . There have been numerous studies on the effect of spinel on refractory castables properties, including the influence of spinel grain size, chemical composition, density, spalling resistance, slag attack resistance, and hot strength . Alumina–spinel castables have also been developed with in situ spinel‐forming material where fine MgO powder taken in batch reacts with Al 2 O 3 fines to form spinel on firing, and fine spinel formed “ in situ ” by the reaction of MgO–Al 2 O 3 in the matrix of alumina–magnesia castable increases resistance to corrosion and slag penetration compared with alumina–spinel castable .…”

Section: Introductionmentioning

confidence: 99%

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Effect of Spinel Kinds on Properties of Alumina—Spinel Castables

Qiu

Ruan

Ouyang

et al. 2014

Int J Applied Ceramic Tech

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Effect of spinel kinds on the properties of alumina—spinel castables was investigated. The results showed that the addition of various kinds of spinels has an effect on the physical and mechanical properties of these refractory castables. The reason is that the Al2O3‐rich spinel precipitated Al2O3 and MgO‐rich spinel solid solution and formed secondary spinel. In addition, stable spinel in castables during heat treatment process was found to be more effective for enhancing cold and hot strength.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Spinel Kinds on Properties of Alumina—Spinel Castables

Qiu

Ruan

Ouyang

et al. 2014

Int J Applied Ceramic Tech

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“…INTRODUCTION The up surge application and request for refractory bricks had motivated this research to investigate the raw clay materials used for production of refractory bricks. The raw clay materials were subjected to standard refractory fireclay brick tests requirement through the tests procedures for chemical, thermal, physical and mechanical properties [1]. Clay as a raw material varied considerably in terms of workability, structure, particle-size distribution, plasticity and mineralogical composition.…”

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confidence: 99%

Influence of Sintering Temperatures on Physico-Mechanical Properties and Microstructure of Refractory Fireclay Bricks

Amkpa¹,

Badarulzaman²,

Aramjat³

2016

IJET

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Abstract-ThisI. INTRODUCTION The up surge application and request for refractory bricks had motivated this research to investigate the raw clay materials used for production of refractory bricks. The raw clay materials were subjected to standard refractory fireclay brick tests requirement through the tests procedures for chemical, thermal, physical and mechanical properties [1]. Clay as a raw material varied considerably in terms of workability, structure, particle-size distribution, plasticity and mineralogical composition. These differences paved way for clays being categorized or classified into plastic clays, flint clays, kaolin clays, fireclays and ball clays [2]. In the refractory industries, they are grouped and referred to as illite, Montmorillonite and kaolinite [3]. Refractories are clay materials that are generally capable of enduring very high temperatures without deformation, structural changes or softening [4]. The type of refractories is determined by the type of refractory requirement for a specific purpose. The types are classified as acid, basic and neutral refractories [5]. Traditionally these clay materials containAl 2 O 3 .SiO 2 .H 2 O to produce alumino-silicates refractory fireclay bricks. They are further classified by temperature. When the temperature is between 1500-1700 0 C, it is branded as refractory e.g. fireclay.The temperaturebetween 1700-2000 0 Cis recognized as high refractory e.g. chromite. When thetemperature is 2000 0 C, it is referred to as super refractory e.g. zircon [5].The applications of refractories are employed in the construction of furnaceslinings, ladles, reactors, ovens and kiln [6]. This disposition proved that the raw clay material is a fireclay and belongs to the alumino-silicate subgroup. The uses for fireclay refractory brick comprise of porous refractory insulation behind furnace linings, refractory fireclay bricks and ladles [7].Refractories are frequently consumed basically in the iron and steel industries [8]. Contamination of refractories clays are usually with limited amount of impurity as contained in the oxides which are CaO, MgO, TiO 2 , Fe 2 O 3 , Mn, SO 3 , ZnO, Cl, K 2 O, P 2 O 5 , Cr 2 O 3 and alkali oxides that acts as fluxing mediator at very high temperature [9]. In the process ofiron and steel production, the use of basic oxygen furnace (BOF) for the molten iron that comes from the blast furnace is decontaminated from the scums.Refractories belonging to silica-alumina have heterogeneous microstructure with bulky grain size and reasonable rate of porosity [10]. In Nigeria, previous investigation work has been done on the characterization of the native refractory raw clay materials for the making of quality refractory fireclay bricks for furnace lining, ladles, ovens and kilns [11]. In many cases, the outcome and results of such previous work were inconclusive and not comprehensive enough to be used or adopted for industrial uses. They were not subjected to standard test requirement for refractory bricks production.The researches for an alterna...

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“…With increased amount of nano‐alumina particles in the castable, the self‐flow value and working time tend to decrease, and the cold crushing strength is enhanced after heat treatment. In addition, Sasan Otroj et al researched the microstructure and phase composition of alumina‐spinel self‐flowing refractory castables containing nano‐alumina particles at different temperatures. The results show that using nanometer‐sized alumina particles with large surface area, the solid phase sintering of the nano‐sized particles and CA 6 formation can occur at 1300°C.…”

Section: Introductionmentioning

confidence: 99%

Optimized microstructure with nano‐alumina and its effects on properties of corundum spinel castables

Zhu

Chen

et al. 2019

Int J Applied Ceramic Tech

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The mechanical properties, thermal shock resistance, and microstructure evolution of corundum spinel castables with different nano-alumina contents were investigated.The results show that the addition of nano-alumina has advantages on the microstructure evolution and properties of castables. An optimum nano-alumina amount is 2 wt%. When nano-alumina addition changes from 0 to 2 wt%, the cold modulus of rupture (CMOR) and cold compressive strength (CCS) improved by 69.7% and 78.1% after firing at 1100°C, respectively. The CMOR and CCS increased by 42.5% and 35.2% after firing at 1500°C, respectively. Meanwhile, the hot modulus of rupture (HMOR) was enhanced by 21.5% to 13.4 MPa. The retained Young's modulus values of castables were improved from 49.6% to 59.6% after eight thermal shock cycles. Furthermore, the HMOR and the retained Young's modulus values of castables slightly reduced when nano-alumina content up to 3 wt%. XRD, DSC, SEM, and EDS analyses revealed that the addition of nano-alumina leads to the formation of calcium dialuminate (CaO·2Al 2 O 3 ) at 1100°C and it is beneficial to the formation of more platelet hibonite (CaO·6Al 2 O 3 ) at 1500°C. As a result of using nano-alumina with large surface area, the solid phase sintering of the nanoscale particles can occur at lower temperatures. Moreover, the mechanical properties and thermal shock resistance of the castables were improved remarkably. K E Y W O R D SMatrix microstructure optimization, Nano-alumina, orundum spinel refractory castables, Thermal shock resistance

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Microstructure and phase evolution of alumina–spinel self-flowing refractory castables containing nano-alumina particles

Cited by 34 publications

References 15 publications

Effect of Spinel Kinds on Properties of Alumina—Spinel Castables

Effect of Spinel Kinds on Properties of Alumina—Spinel Castables

Influence of Sintering Temperatures on Physico-Mechanical Properties and Microstructure of Refractory Fireclay Bricks

Optimized microstructure with nano‐alumina and its effects on properties of corundum spinel castables

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