Influence of the Manufacturing Technique on the Macro‐ and Microstructure of Reticulated Carbon‐Bonded Alumina Foams

Schramm, Alina; Voigt, Claudia; Hubálková, Jana; Scharf, Christiane; Aneziris, Christos G.

doi:10.1002/adem.201900525

Cited by 5 publications

(1 citation statement)

References 17 publications

(73 reference statements)

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“…Aqueous slurry was prepared, using the following additives: the temporary binder ammonium lignosulfonate (Otto‐Dille, Germany), the dispersion agent Castament VP 95 L (BASF, Germany), and the antifoam agent Contraspum K1012 (Zschimmer&Schwarz, Germany). The slurry layers were applied onto a polyurethane foam template (10 ppi) via rolling and spray coating, as described by Schramm et al, [ 20 ] following the Schwartzwalder technique. [ 21 ] After a drying period of 24 h at room temperature, the filter substrates were placed inside of petcoke‐filled steel retorts and heat treated at 800 °C for 3 h, resulting in the pyrolysis of the PU foam template, leaving the carbon‐bonded ceramic foam structure behind.…”

Section: Methodsmentioning

confidence: 99%

Immersion Testing of Variously Coated Ceramic Foam Filters in an AZ91 Magnesium Melt

et al. 2021

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Due to its low density, high specific strength, and resource availability, magnesium and its alloys, such as AZ91, have a high potential for various lightweight applications. [1][2][3] A major hindrance for its widespread processing and use is its high reactivity, contributing to high dross-and sludge formation in the melt, which results in the metal being prone to corrosion and containing high quantities of nonmetallic inclusions, if the handling of the melt has not been accurate. The inclusions can be divided into oxide films, lumps, and clusters, as well as intermetallic particles; gas-and shrinkage pores, may also be present. [1][2][3][4][5] While measures are taken to protect and cleanse magnesium melts on industrial scale, such as gas purging treatments by Ar, N 2 , or Cl 2 , the usage of a variety of possible cover gases or fluxes and the optimization of the casting system toward a high grade of enclosure, [1,6] the application of ceramic foam filters is seen as a promising method for cleansing the melt and improving the mechanical properties of the casting. [7][8][9] Ideally, an auxiliary addition of fluxes would be avoided, while delivering the same quality of melt cleanliness. [10][11][12] Wu et al. emphasized the effectiveness of ceramic foam filters made from MgO or Al 2 O 3 in AZ91, improving the elongation-to-failure of cast samples up to relative 58%. [13] In contrast to oxidic, sintered filters, carbon-bonded ceramic foam filters show higher resistance toward thermal shock and creep deformation, as well as lower energy consumption during their manufacture, due to their lower manufacturing temperature. [14] After carbon-bonded alumina filters showed promising results in the filtration of steel melts, [15] short-term immersion tests in AZ91 have been carried out to evaluate their applicability in a magnesium alloy melt. Interface reactions between the AZ91 melt and variously coated ceramic Al 2 O 3 -C filters have been investigated after immersion times of 10-120 s. [16] The investigated filter coatings consisted of Al 2 O 3 , MgO-C, MgAl 2 O 4 , or carbon nanotubes/ alumina nanosheets. The formation of MgO in situ layers was shown on filter surfaces containing Al 2 O 3 or MgAl 2 O 4 . [16] Therefore, the next step toward assessing the applicability of oxidic as well as carbon-bonded ceramic foam filters in the field of magnesium melt filtration is the evaluation of their long-term resistance toward the magnesium melt, with a special regard toward melt contamination and inclusion content.In this study, additional ceramic foam filter materials, namely ZrO 2 [13] and MgAlON, [17] were added to the selected materials

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Section: Methodsmentioning

confidence: 99%

Immersion Testing of Variously Coated Ceramic Foam Filters in an AZ91 Magnesium Melt

et al. 2021

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Novel Ceramic Foam Filter Materials for the Filtration of Magnesium Alloy Melts

Schramm,

Aneziris,

Scharf

2024

Springer Series in Materials Science

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Cleanliness of magnesium alloy melts plays an important role in producing high-quality, lightweight products exemplary for the automotive or aircraft industry with high-quality standards. Therefore, the applicability of ceramic foam filters in the active and reactive filtration of magnesium alloys was explored as an option of metallurgical refining. Carbon-bonded alumina foams were selected in their uncoated as well as variously coated states. To evaluate the applicability of selected ceramic filter materials, various tests were applied, investigating filter properties, interface interactions, melt cleanliness and wetting behavior of the filter, such as sessile drop tests, immersion and filtration tests, and metallographic evaluation of AZ91. Immersion tests in AZ91 at 680 °C for up to 60 min showed the durability of coated and uncoated Al2O3-C and the formation of finely-structured MgO in-situ layers on any alumina- or spinel-containing surfaces in contact with molten AZ91. These layers, resulting from interface reactions with the melt, are regarded to have the potential to attract and bind oxidic inclusions from the metallic melt during filtration, as AZ91 samples showed reduced inclusion amounts after their contact with Al2O3-C filters. Another milestone was the synthesis of MgAlON as a filter coating, proven to be resistant towards the reactive magnesium alloy melt.

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Granulation of Mn-based perovskite adsorbent for cyclic Hg0 capture from coal combustion flue gas

Yang

et al. 2023

Chemical Engineering Journal

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Influence of the Manufacturing Technique on the Macro‐ and Microstructure of Reticulated Carbon‐Bonded Alumina Foams

Cited by 5 publications

References 17 publications

Immersion Testing of Variously Coated Ceramic Foam Filters in an AZ91 Magnesium Melt

Immersion Testing of Variously Coated Ceramic Foam Filters in an AZ91 Magnesium Melt

Novel Ceramic Foam Filter Materials for the Filtration of Magnesium Alloy Melts

Granulation of Mn-based perovskite adsorbent for cyclic Hg0 capture from coal combustion flue gas

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