Ductile behavior of fine-grained, carbon-bonded materials at elevated temperatures

Solarek, Johannes; Himcinschi, Cameliu; Klemm, Yvonne; Aneziris, Christos G.; Biermann, Horst

doi:10.1016/j.carbon.2017.06.041

Cited by 25 publications

(33 citation statements)

References 29 publications

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“…As reported recently, Al 2 O 3 ‐C foam filters show brittle material behavior up to 1300 °C . The frequent drops of force result from the porous and brittle nature of the filter material at 1100 °C and are caused by the unbalanced force distribution in the struts.…”

Section: Resultssupporting

confidence: 52%

“…As reported recently, Al 2 O 3 -C foam filters show brittle material behavior up to 1300 C. [17] The frequent drops of force result from the porous and brittle nature of the filter material at 1100 C and are caused by the unbalanced force distribution in the struts. The foam structures were loaded until the ultimate stress of a single strut was reached, resulting in local fracture.…”

Section: Mechanical Propertiesmentioning

confidence: 77%

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Influence of Carbon Nanotubes‐Based Coatings on the High‐Temperature Compression Strength of Al₂O₃‐C Foam Filter Structures

et al. 2019

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Materials for steel‐melt filtration have to fulfill different thermomechanical requirements and especially withstand the thermal shock attack in the beginning of casting. In particular, carbon‐bonded alumina materials provide an excellent thermomechanical performance and have been used in functional components such as submerged entry nozzles, stoppers, and sliding gates for several years. The present study investigates the mechanical high‐temperature behavior of Al2O3‐C foam filter structures with coatings based on carbon nanotubes+Al2O3‐nanosheets (CNT‐ANS) and carbon nanotubes+Al2O3‐nanospheres (CNT‐ANB) at 1100 and 1450 °C. The foam filters are tested in an electromechanical testing machine under argon atmosphere in quasi‐static compression. The tests show a brittle material behavior at 1100 °C with higher compressive strength of the coated filter samples. At 1450 °C, a loss of strength occurs, accompanied by an increase in plastic deformation. Rupture of struts and behavior of the coatings are microstructurally analyzed by scanning electron microscopy. As the mechanical load during the tests is much longer than in real immersion tests, the high‐temperature performance is considered trustworthy.

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Section: Resultssupporting

confidence: 52%

Section: Mechanical Propertiesmentioning

confidence: 77%

Influence of Carbon Nanotubes‐Based Coatings on the High‐Temperature Compression Strength of Al₂O₃‐C Foam Filter Structures

et al. 2019

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“…At lower temperatures, first, small cracks and gaps are closed due to the thermal expansion mismatch among the particles and the matrix. Increasing the temperature, larger sized cracks and gaps are also progressively closed. VII–VIII: The increase in the Young's modulus during the second dwell time at 1000°C was possibly motivated by a viscoplastic behavior of the carbon matrix . As the thermal expansion coefficient of the alumina is higher than the matrix one, compressive stresses are generated at the alumina‐matrix interface (thermal stresses).…”

Section: Resultsmentioning

confidence: 99%

“…As the thermal expansion coefficient of the alumina is higher than the matrix one, compressive stresses are generated at the alumina‐matrix interface (thermal stresses). Solareck et al and Liu et al demonstrated that, at high temperatures, creep effects start to affect the behavior of carbon‐bonded materials. Therefore, due to local creep, the matrix deforms more easily, allowing the alumina and graphite to expand further.…”

Section: Resultsmentioning

confidence: 99%

“…VII-VIII: The increase in the Young's modulus during the second dwell time at 1000°C was possibly motivated by a viscoplastic behavior of the carbon matrix. 30,[43][44][45] As the thermal expansion coefficient of the alumina is higher than the matrix one, compressive stresses are generated at the alumina-matrix interface (thermal stresses). Solareck et al [43][44][45] and Liu et al 30 demonstrated that, at high temperatures, creep effects start to affect the behavior of carbon-bonded materials.…”

Section: Resultsmentioning

confidence: 99%

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On the nonlinear behavior of Young's modulus of carbon‐bonded alumina at high temperatures

et al. 2018

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The origin of the nonlinear behavior of the Young's modulus (E) of carbon‐bonded alumina at high temperatures was addressed, based on the microstructural changes observed during processing and their thermo‐mechanical properties. Impulse excitation technique, thermogravimetric analysis, porosity measurement, and scanning electron microscopy were conducted in order to highlight and explain the E behavior. The finite element model of a virtual microstructure was simulated and the results attained are in good agreement with the experimental data. The tests revealed that the Young's modulus of a cured sample heated from room temperature up to 500°C was governed by the release of volatiles. Above this temperature, the thermal expansion mismatch among alumina, graphite, and the carbon matrix is dominant resulting in an increase in the effective Young's modulus. During cooling, crack networks and gaps between alumina particles and the carbon matrix were developed. The former were induced by volatile release and by the graphite's highly anisotropic thermal expansion. The latter was derived by the thermal expansion mismatch between the alumina and the carbon matrix. The closure of the gaps and cracks governed the expansion behavior during the second heating cycle and a nonlinear effective Young's modulus increase as a function of temperature was observed.

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Carbon‐Bonded Alumina Spaghetti Filters by Alginate‐Based Robo Gel Casting

et al. 2019

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Metal melt filtration has become very popular over the past decades as it provides the possibility of removing nonmetallic inclusions from metal melts and reduces the amount of flow turbulence during mold filling. However, especially, the filtration of steel melts is associated with particularly harsh conditions which might require special filter solutions regarding increased strength and specified flow path. Herein, a novel approach for the manufacturing of cellular ceramic materials is investigated. Thereby, a slurry containing alginate is pumped into an aqueous solution containing Ca2+ or Ba2+ ions. The natural capability of the alginate for gelation leads to the in situ stiffening of the slurry in contact with the cross‐linking solution. Periodic strut patterns can be realized by moving the nozzle with the aid of a computer‐assisted robotic system. The influence of sodium alginate and solid content on the slurry rheology and the process parameters is analyzed based on a fixed carbon‐bonded alumina composition. Furthermore, alternative combinations of alginate types and alkaline earth sources are tested on their suitability for gel casting and their influence on the residual carbon content after pyrolysis. A suitable filter is successfully applied in steel melt immersion tests.

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Ductile behavior of fine-grained, carbon-bonded materials at elevated temperatures

Cited by 25 publications

References 29 publications

Influence of Carbon Nanotubes‐Based Coatings on the High‐Temperature Compression Strength of Al₂O₃‐C Foam Filter Structures

Influence of Carbon Nanotubes‐Based Coatings on the High‐Temperature Compression Strength of Al₂O₃‐C Foam Filter Structures

On the nonlinear behavior of Young's modulus of carbon‐bonded alumina at high temperatures

Carbon‐Bonded Alumina Spaghetti Filters by Alginate‐Based Robo Gel Casting

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Ductile behavior of fine-grained, carbon-bonded materials at elevated temperatures

Cited by 25 publications

References 29 publications

Influence of Carbon Nanotubes‐Based Coatings on the High‐Temperature Compression Strength of Al2O3‐C Foam Filter Structures

Influence of Carbon Nanotubes‐Based Coatings on the High‐Temperature Compression Strength of Al2O3‐C Foam Filter Structures

On the nonlinear behavior of Young's modulus of carbon‐bonded alumina at high temperatures

Carbon‐Bonded Alumina Spaghetti Filters by Alginate‐Based Robo Gel Casting

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Product

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Influence of Carbon Nanotubes‐Based Coatings on the High‐Temperature Compression Strength of Al₂O₃‐C Foam Filter Structures

Influence of Carbon Nanotubes‐Based Coatings on the High‐Temperature Compression Strength of Al₂O₃‐C Foam Filter Structures