Calcium Aluminate Reactive Coatings on Carbon‐Bonded Alumina Filters for Clean Steel Approaches

Storti, Enrico; Farhani, Mahdi; Aneziris, Christos G.; Wöhrmeyer, Christoph; Parr, Christopher

doi:10.1002/srin.201700247

Cited by 32 publications

(29 citation statements)

References 16 publications

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“…The results of the ASPEX analysis on the steel samples are presented in Table and , where the detected inclusions are classified by size and chemistry, respectively. It is observed that the use of a filter had a mild impact on the total number of inclusions, compared with our previous investigations . Whereas the reference sample showed the maximum amount of inclusions within the 1–3 μm 2 size range, nanocoated filters presented the peak at 10–20 μm 2 .…”

Section: Resultscontrasting

confidence: 58%

Filter Coatings Based on Combination of Nanomaterials for Steel Melt Filtration

et al. 2019

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Carbon‐bonded alumina foam filters are coated using special slurries based on graphene oxide (GO), carbon nanotubes (CNTs), and alumina nanosheets. The aim of such filters is to reduce the concentration of nonmetallic inclusions in the steel melt prior to casting into the molds. To assess the purification efficiency of the coated filters, a steel casting simulator is used. After immersion for a short time into steel melts with artificially generated alumina impurities, the filters are analyzed by optical microscopy and scanning electron microscopy. In addition, the population of remaining inclusions in the treated steel is investigated by the means of a special scanning electron microscope. The results show that, compared with a reference melt where no filter is used, the nanocoated filters cause inclusion growth and the formation of new silicate inclusions. The best purification efficiency, regarding only alumina inclusions, is given by the GO–C sample, whereas the combination of GO with alumina nanosheets or CNTs deliver worse performance.

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Section: Resultscontrasting

confidence: 58%

Filter Coatings Based on Combination of Nanomaterials for Steel Melt Filtration

et al. 2019

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“…Consequently, the structures most likely consist of calcium aluminates and/or alumina. Calcium aluminates were found to have a favorable behavior on the steel melt cleanliness when applied as filter coating . In the present case, calcium is present due to the gel‐casting procedure.…”

Section: Resultsmentioning

confidence: 65%

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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“…Summary of processes in a steel melt during active and reactive cleaning by ceramic foam filters, including a) principal scheme and examples of main reaction effects: b) oxide layer deposition on filter, c) NMIs adhesion on filter, d) agglomeration of NMIs in a steel melt …”

Section: Discussionmentioning

confidence: 99%

“…Coating abbreviations in Table denote alumina (Al 2 O 3 , “+A” coating), alumina‐based slurry (AC5, “+AC5” coating), carbon nanotubes and alumina nanosheets (CNT and ANS, “+Nano” coating) and calcium hexaluminate (CA6, “+CA6” coating). Detailed description on the coatings design, production, and properties are given elsewhere …”

Section: Methodsmentioning

confidence: 99%

Effect of Filter Functional Coating on Detrimental Nonmetallic Inclusions in 42CrMo4 Steel and Its Resulting Mechanical Properties

et al. 2019

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Carbon‐bonded ceramic foam filters with different functional coatings are immersed in a 42CrMo4 steel melt within a steel casting simulator. The solidified steel is analyzed with respect to the size distribution and the chemical composition of the remaining nonmetallic inclusions (NMI). Cyclic loading and quasi‐static tests are performed to determine the fatigue limit, the strength, deformability, and toughness of the steel after filter immersion. The immersion of filter with calcium hexaluminate (CA6) coating significantly reduces the population of small (4–20 μm) NMIs. This leads to an increased deformability and, thus, ability for energy dissipation during deformation. However, the maximum size of NMIs is increased from 100 to 150 μm, which results in fatigue limit reduction, despite the decrease in NMIs total density. The majority of inclusions are found to be pure alumina. Large (up to 150 μm) plate‐like alumina inclusions introduce most of the detrimental effects on cyclic strength, whereas significant effect on quasi‐static strength is not found.

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Calcium Aluminate Reactive Coatings on Carbon‐Bonded Alumina Filters for Clean Steel Approaches

Cited by 32 publications

References 16 publications

Filter Coatings Based on Combination of Nanomaterials for Steel Melt Filtration

Filter Coatings Based on Combination of Nanomaterials for Steel Melt Filtration

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

Effect of Filter Functional Coating on Detrimental Nonmetallic Inclusions in 42CrMo4 Steel and Its Resulting Mechanical Properties

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