Reasons for crack propagation and strength loss in refractory castables based on changes in their chemical compositions and micromorphologies with heating: special focus on the large blocks

Kazemi, Nader

doi:10.1080/21870764.2019.1597957

Cited by 16 publications

(9 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the slope of the curve (directly related to the permeability) for the LC‐PP batch was clearly larger. PP fibers are in fact specifically used to increase the permeability of castables 8 . Moreover, the permeability of all samples slightly increased with the applied pressure.…”

Section: Resultsmentioning

confidence: 90%

“…Alternatively, metallic or Kevlar fibers can be used to increase the green strength and allow the castable to withstand higher thermomechanical stresses without cracking. 7,8 Both the volume fraction of fibers and their geometry (shape, thickness, and length) have a significant influence on the castable's permeability, which ultimately affects the drying behavior. 9 Salomao et al 10 reported that a 0.09 wt% addition of polypropylene (PP) fibers (3 mm long, 15 𝜇m in diameter) effectively improved the permeability of highalumina castables.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electrospun fibers as drying additive in cement‐bonded alumina castables

Storti

Himcinschi

Neumann

et al. 2022

Int J Applied Ceramic Tech

View full text Add to dashboard Cite

A simple system to produce titanium dioxide precursor fibers by electrospinning was developed. The phase composition of the fibers was analyzed before and after heat treatment by means of Raman spectroscopy. The effect of these fibers and commercial polypropylene fibers (PP) on low‐cement high‐alumina castables was evaluated. Thermogravimetry was used to investigate the drying behavior of the different batches. In addition, the permeability of sintered cylinders was compared. Elastic moduli and cold modulus of rupture were measured on sintered and on thermally shocked samples to evaluate the thermal shock resistance. As in our previous work, the results showed that the fiber addition was beneficial for the drying behavior. However, the use of electrospun fibers likely caused water retention in the samples during storage. The batch containing PP fibers showed the highest final permeability, confirmed also by mercury intrusion porosimetry and by scanning electron microscopy. Otherwise, the precursor fibers left no pore channel after sintering and the permeability of this batch was the lowest. Thermal shock had no clear impact on bulk density or open porosity for any of the batches. Due to the presence of calcium oxide from the cement binder, hibonite (CaAl12$_{12}$O19$_{19}$) was detected by XRD alongside corundum in all samples.

show abstract

Section: Resultsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Electrospun fibers as drying additive in cement‐bonded alumina castables

Storti

Himcinschi

Neumann

et al. 2022

Int J Applied Ceramic Tech

View full text Add to dashboard Cite

show abstract

“…At high temperature, the diffusion rate of O 2− in the direction perpendicular to the c ‐axis is faster than the diffusion rate in the direction parallel to the c‐axis, thereby preferentially generating flake or plate‐like crystals interspersed between the corundum phase and the matrix during the formation of CA 6 7,8 . The in‐situ CA 6 interface layer generated around the aggregates can improve the TSR of the castables by improving the bonding strength of aggregates and matrix, thus, making the crack propagation along the edge of grain boundary for multiple times, and the crack propagation path becomes tortuous y 43–45 …”

Section: Resultsmentioning

confidence: 99%

Preparation of Al₂O₃@CaCO₃ aggregates and its effects on the thermal shock resistance of Al₂O₃‐MgO castables

Ding

Xiao

et al. 2021

Int J Applied Ceramic Tech

View full text Add to dashboard Cite

Al 2 O 3 @CaCO 3 aggregates were prepared by impregnating corundum aggregates (particle sizes with 3-1 and 5-3 mm) in precursor solutions (Calcium hydrogen citrate, CaHC 6 H 5 O 7 ) followed by heat treatment at 430°C. The phase composition and microstructure of the coatings were characterized via X-ray diffraction and scanning electron microscope, respectively. The novel aggregates were used in Al 2 O 3 -MgO castables. The effects of the Al 2 O 3 @CaCO 3 aggregates on the physical properties and thermal shock resistance (TSR) of castables were investigated. The results show that uniform CaCO 3 coating of aggregates (C15) with thickness about 10 µm can be attained when the concentration of Ca 2+ in solution was 0.15 mol L −1 . There was a strong bonding between the aggregates and coating that was constituted by particles with size about 0.2 µm. Both improving physical and TSR properties of the castables are related with the unique layer structure, calcium hexaluminate (CA 6 ) layer in-situ formed at the aggregate-matrix interface, of added Al 2 O 3 @CaCO 3 aggregates. There is a mass of multi-deflection of cracks along with the CA 6 layer which consumes more fracture surface energy. The castables with C15 exhibit optimal TSR and the residual strength ratio after the thermal shock test is 29.5%, which is 12.8% higher than the castables with corundum aggregates.

show abstract

“…They concluded that only SiC oxidation and anorthite formation are predicted in the 400 − 1200°C temperature range. While Kazemi [29] explained that in the presence of CaO, the superfine silica and alumina particles react with this CaO at high T° (1000-1500°C) leading to the formation of low melting phases, such as anorthite (CaO. Al 2 O 3 .2SiO 2 ) and gehlenite (2CaO.Al 2 O 3 .SiO 2 ) and causes reduction of the strength of the refractory at high temperatures.…”

Section: Effect Of Silica Fume On the Weight And Dimensions Of Castabmentioning

confidence: 99%

Influence of lithium carbonate and superplasticizer as admixtures on low calcium dialuminate cement castable submitted to thermal shock

Tchamba

Nkeng

Randy

et al. 2021

Journal of Asian Ceramic Societies

View full text Add to dashboard Cite

The purpose of this study was to investigate the hot properties of low calcium dialuminate cement castable as binder with varying amount of Li 2 CO 3 and castament FS20 superplasticizer as admixtures. Thermal damage test was carried out through quenching in air for five cycles ΔT = 1175°C. The samples were preheated at 1500°C for 2 h. The results gave a retained Young's modulus of low-cement castable with 0.3 wt.% Li 2 CO 3 and 0.5 wt.% castament down to 10.36% while 0.1 wt.% Li 2 CO 3 and 0.5 wt.% castament showed a retained modulus down to 13.47%. For the samples without admixture, the loss of Young modulus was 92.4% and 93.7% with 0.3 wt.% of Li 2 CO 3 admixture. The superplasticizer has a great effect on thermal shock resistance of low calcium dialuminate cement castable. The results confirmed that 0.1 wt%Li 2 CO 3 and 0.5 wt% castament have better thermal shock resistance and longer service life for applications in refractories. The increase of mass of the refractory materials during five thermal shock cycles in air is the main factor affecting the degradation of this refractory material due to the oxidation of SiC to SiO 2 .

show abstract

Reasons for crack propagation and strength loss in refractory castables based on changes in their chemical compositions and micromorphologies with heating: special focus on the large blocks

Abstract: To cite this article: Nader Kazemi (2019) Reasons for crack propagation and strength loss in refractory castables based on changes in their chemical compositions and micromorphologies with heating: special focus on the large blocks,

Cited by 16 publications

References 55 publications

Electrospun fibers as drying additive in cement‐bonded alumina castables

Electrospun fibers as drying additive in cement‐bonded alumina castables

Preparation of Al₂O₃@CaCO₃ aggregates and its effects on the thermal shock resistance of Al₂O₃‐MgO castables

Influence of lithium carbonate and superplasticizer as admixtures on low calcium dialuminate cement castable submitted to thermal shock

Contact Info

Product

Resources

About

Reasons for crack propagation and strength loss in refractory castables based on changes in their chemical compositions and micromorphologies with heating: special focus on the large blocks

Abstract: To cite this article: Nader Kazemi (2019) Reasons for crack propagation and strength loss in refractory castables based on changes in their chemical compositions and micromorphologies with heating: special focus on the large blocks,

Cited by 16 publications

References 55 publications

Electrospun fibers as drying additive in cement‐bonded alumina castables

Electrospun fibers as drying additive in cement‐bonded alumina castables

Preparation of Al2O3@CaCO3 aggregates and its effects on the thermal shock resistance of Al2O3‐MgO castables

Influence of lithium carbonate and superplasticizer as admixtures on low calcium dialuminate cement castable submitted to thermal shock

Contact Info

Product

Resources

About

Preparation of Al₂O₃@CaCO₃ aggregates and its effects on the thermal shock resistance of Al₂O₃‐MgO castables