Thermomechanical behaviour of Al2O3–MgO–C refractories under non-oxidizing atmosphere

Muñoz, Vanesa; Martínez, A.G. Tomba

doi:10.1016/j.ceramint.2014.10.146

Cited by 22 publications

(19 citation statements)

References 16 publications

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“…The explanations are discussed differently in literature. Some authors argue that the minimum of strength corresponds to the thermoplastic point of the bonding agent . This is not the case in this study, since all specimens were preheated to 1400°C before testing.…”

Section: Discussionmentioning

confidence: 78%

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High‐Temperature Compression Deformation Behavior of Fine‐Grained Carbon‐Bonded Alumina

et al. 2016

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Carbon-bonded alumina with 33 wt% residual carbon was tested in compression at room temperature and at temperatures between 700°C and 1500°C in quasi-static tests, creep tests, and stress relaxation tests. Therefore, a new high-temperature test set up with inert gas chamber and inductive heating was used. The tests were accomplished by investigations of microstructure and Young's modulus. At room temperature, the results exhibit a pronounced hysteresis for the first loading cycle, which almost completely disappeared in subsequent cycles. The creep tests showed characteristic curves for compression whereas primary and secondary (stationary) creep occurred. Above 1000°C, a strong increase in creep rate was detected, whereas almost no creep was observed below this temperature. All creep curves were approximated with the models of logarithmic and Andrade creep. The activation energy for creep was found to be 263 kJ/mol above 1150°C. The resistance against stress relaxation showed an anomaly with a minimum between 1000°C to 1200°C and a maximum between 1300°C and 1400°C.M. Rigaud-contributing editor Manuscript No. 37046.

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Section: Discussionmentioning

confidence: 78%

“…Muñoz et al and Musante et al explained the increase in strength with temperature for MgO–C and Al 2 O 3 –MgO–C refractories with the formation of a new hardening phase at certain temperatures. These phases are formed due to addition of antioxidants, which was not the case for the material tested in this study.…”

Section: Discussionmentioning

confidence: 98%

High‐Temperature Compression Deformation Behavior of Fine‐Grained Carbon‐Bonded Alumina

et al. 2016

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“… During the wait, other chemical and mineralogical changes happen within the refractory brick, especially those involving Al, Si and MgO; some of these contribute to enhancing the mechanical properties of the bricks [33], although they may also contribute to increased porosity volume [34]. In spite of the oxidant atmosphere, the loss of graphite and/or residual carbon does not seem to contribute to refractory degradation in a significant way.…”

Section: Degradation Mechanisms In Amc Bricks By Aluminate Calcium Slagsmentioning

confidence: 99%

Post-mortem analysis of alumina-magnesia-carbon refractory bricks used in steelmaking ladles

Calvo

Pena

Martínez

2019

Ceramics International

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Post-mortem studies in secondary steelmaking ladles are an important way to determine the factors related to Alumina-Magnesia-Carbon (AMC) refractory corrosion. AMC refractory bricks installed in the impact zone of a steelmaking ladle bottom were analyzed after 100 castings. X-ray diffraction, X-ray fluorescence chemical analysis, reflected optical light microscopy, scanning electron microscopy, energy dispersive X-ray spectrometry, density and porosity measurements, and mercury porosimetry were used to analyze the chemical and physical characteristics of the slag, the unused refractory and the slag+steel attacked bricks. The corrosion process produced a specific microstructure characterized by: i) a thick discontinuous slag layer composed by secondary spinel+steel+liquid; ii) a thick dense, cracked, and continuous layer consisting of calcium aluminates+steel+liquid at the slag/refractory interface; iii) next to this layer, a wide densified layer with a uniform microstructure in which corundum aggregates and spinel crystals were linked together by elongated CaAl 12 O 19 crystals.The formation of these reaction layers constituted a barrier that effectively suppressed the massive slag penetration and surely reduced the wear rate. Thermodynamic calculations based on simplified and complex condensed phase equilibrium diagrams, were used to further understanding of the corrosion mechanism.During the service of the ladle, when the secondary metallurgy takes place (i.e., the adjustment of the steel composition), refractories of the working lining are exposed to very aggressive conditions: the high temperature of the process, the oxidant atmosphere that prevails because it is an open vessel, and contact with corrosive agents, especially the liquid slag, among others. The refractories are zoned in type and thickness to provide maximum ladle performance at a minimum cost.However, the particular loading of each refractory depends not only on its location in the vessel, but also on the stage of the ladle cycle [6]: the lifetime of the refractory in the impact zone of the bottom is limited by the thermo-mechanical loading, thermal shock and erosion, which are developed during the tapping and the refining of the steel. For this reason, the use of refractories with high mechanical strength and erosion resistance at high temperatures is convenient, which is why alumina is incorporated into the refractory formulation. However this addition makes the brick incompatible with the ladle slag. Nevertheless, liquid slag is in contact with these refractories during the casting stage, giving corrosion a chance to occur before slag solidification. This paper deals with the degradation of AMC bricks used in the impact zone of a steelmaking ladle (post-mortem study) with a focus on slag corrosion, bearing in mind that it undoubtedly contributed to the refractories' wear. The literature on the corrosion of AMC bricks is scarce, and the papers available concern work implemented in lab tests to the study the phenomenon [7-9]. These tests provi...

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“…3,30 It is known from the literature that the amorphous carbon fibers also can enhance the thermal shock resistance of carbon containing refractories by "pulling out" mechanism. 3,30 It is known from the literature that the amorphous carbon fibers also can enhance the thermal shock resistance of carbon containing refractories by "pulling out" mechanism.…”

Section: Mechanical Properties and Thermal Shock Resistancementioning

confidence: 99%

“…This behavior was mainly attributed to the high content of flake graphite as it can decrease the thermal stress by rapid heat transfer and inelastic deformation. 3,30 It is known from the literature that the amorphous carbon fibers also can enhance the thermal shock resistance of carbon containing refractories by "pulling out" mechanism. 16 High thermal stress could be easily generated in the thermal cycling of the low carbon Al 2 O 3 -C refractory, owing to the more pronounced thermal expansion during heating, as shown in Figure 7.…”

Section: Mechanical Properties and Thermal Shock Resistancementioning

confidence: 99%

Microstructure, properties, and application of low carbon Al₂O₃‐C refractories used as submerged entry nozzles

Bao

Bao³

et al. 2019

Int J Applied Ceramic Tech

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With the aim to achieve the application of low carbon Al2O3‐C refractory as submerged entry nozzle (SEN) materials, a comprehensive study on the microstructure, thermo‐mechanical properties, as well as application performance during use in the continuous casting was carried out by comparing with the traditional one. Both hot and cold modulus of ruptures of the low carbon Al2O3‐C refractory were superior to the traditional one, and its thermal shock resistance still kept in an acceptable level. The increase in the amount of SiC whiskers and the enhancement in the sintering are considered as the strengthening mechanism. In the industrial trial, the rapid loss of graphite caused by the large level fluctuation made the traditional Al2O3‐C refractory more susceptible to flux corrosion. For the low carbon Al2O3‐C refractory, however, the dense structure and the adhesion of viscous slag layer suppressed the slag penetration. Besides, the remaining SiC phases were also difficult to be wetted and dissolved by the flux. As a consequence, a better corrosion resistance was obtained, achieving a decrease of 27.6% in the average depth of the corrosion groove after working for 8 hous.

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Thermomechanical behaviour of Al2O3–MgO–C refractories under non-oxidizing atmosphere

Cited by 22 publications

References 16 publications

High‐Temperature Compression Deformation Behavior of Fine‐Grained Carbon‐Bonded Alumina

High‐Temperature Compression Deformation Behavior of Fine‐Grained Carbon‐Bonded Alumina

Post-mortem analysis of alumina-magnesia-carbon refractory bricks used in steelmaking ladles

Microstructure, properties, and application of low carbon Al₂O₃‐C refractories used as submerged entry nozzles

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Thermomechanical behaviour of Al2O3–MgO–C refractories under non-oxidizing atmosphere

Cited by 22 publications

References 16 publications

High‐Temperature Compression Deformation Behavior of Fine‐Grained Carbon‐Bonded Alumina

High‐Temperature Compression Deformation Behavior of Fine‐Grained Carbon‐Bonded Alumina

Post-mortem analysis of alumina-magnesia-carbon refractory bricks used in steelmaking ladles

Microstructure, properties, and application of low carbon Al2O3‐C refractories used as submerged entry nozzles

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Microstructure, properties, and application of low carbon Al₂O₃‐C refractories used as submerged entry nozzles