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Christos G. Aneziris - One of the best experts on this subject based on the ideXlab platform.

  • Aluminum Melt Filtration with Carbon Bonded Alumina Filters.
    Materials (Basel Switzerland), 2020
    Co-Authors: Claudia Voigt, Tilo Zienert, Jana Hubálková, Beate Fankhänel, Michael Stelter, Alexandros Charitos, Christos G. Aneziris
    Abstract:

    The wetting behavior was measured for Al2O3-C in contact with AlSi7Mg with a conventional sessile drop test (vacuum, 950 °C and 180 min) and a sessile drop test with a capillary purification unit (vacuum, 730 °C and 30 min). The conventional test yielded contact angles of around 92°, whereas the sessile drop measurement with capillary purification showed a strongly non-wetting behavior with a determined apparent contact angle of the rolling drop of 157°. Filtration tests, which were repeated twice, showed that the Al2O3-C filter possessed a better Filtration behavior than the Al2O3 reference filter. For both Filtration trials, the PoDFA (porous disc Filtration analysis) index of the Al2O3-C filter sample was equal to half of the PoDFA index of the Al2O3 reference filter sample, indicating a significantly improved Filtration performance when using Al2O3-C filter. Notable is the observation of a newly formed layer between the aluminum and the Al2O3-C coating. The layer possessed a thickness between 10 µm up to 50 µm and consisted of Al, C, and O, however, with different ratios than the original Al2O3-C coating. Thermodynamic calculations based on parameters of the wetting and Filtration trials underline the possible formation of an Al4O4C-layer.

  • Influence of carbon content and coking temperature on the biaxial flexural strength of carbon-bonded alumina at elevated temperatures
    Carbon, 2020
    Co-Authors: H. Zielke, Cameliu Himcinschi, Martin Abendroth, Meinhard Kuna, Tony Wetzig, Christos G. Aneziris
    Abstract:

    Abstract Open cell ceramic foam filters are used for metal Melt Filtration to enhance the quality of cast products by reducing non-metallic inclusions and generating calm mold fill with less turbulences. A new generation of filters made of carbon-bonded alumina show an increased thermal shock resistance but a lower strength. The filters have to withstand high thermal and mechanical loads due to the Filtration process, whereas a temperature dependent mechanical characterization of the bulk material is required. This contribution concentrates on the influence of carbon content and coking temperature, which are two important manufacturing process parameters. In the ball on three balls test miniaturized disk-shaped specimens are loaded with a spherical tipped punch at temperatures up to 1500 ∘ C until failure occurs. The fracture stress is calculated and used to analyze the material strength by means of Weibull distribution. Two different mechanisms are identified, which change the micro-structure and therewith the strength of the material. Additionally, Raman spectroscopy supports the interpretation of the achieved results of the mechanically tested specimens.

  • Crack propagation behaviour of carbon free and carbon bonded alumina based filter materials
    Ceramics International, 2020
    Co-Authors: Marc Neumann, Tony Wetzig, Jens Fruhstorfer, Vicky Lampert, Hans Jelitto, Gerold A. Schneider, Christos G. Aneziris
    Abstract:

    Abstract The room temperature handling of ceramic foam filters for steel Melt Filtration strongly depends on the mechanical properties of the materials. Against this background, the filter materials Al2O3, Al2O3 – C, and Al2O3–ZrO2 – TiO2 were compared regarding the crack growth exponent n, R-curve behaviour, and energy release during crack growth. Besides, for pure alumina and alumina with zirconia and titania additions, the influence of grain size was addressed. Despite significant differences in Young's Modulus and plateau crack resistance of the R-curve, comparable n were found for Al2O3 - and Al2O3–C -materials. In contrast, the behaviour of the Al2O3–ZrO2 – TiO2 -material differed in many regards, e.g. in the scale of n or in the energy release during crack advance. Moreover, a statistical analysis of the variances in n and the scatter of the evaluated R-curves revealed a reciprocal relation between the scatter in n and the smoothness of the found R-curves.

  • impact of spinel forming systems fe mg mn al o as functional coating materials for carbon bonded alumina filters on steel Melt Filtration
    Ceramics International, 2019
    Co-Authors: Benjamin Bock, Steffen Dudczig, Gert Schmidt, Anne Schmidt, Edyta Sniezek, Jacek Szczerba, Christos G. Aneziris
    Abstract:

    Abstract Since solid, non-metallic inclusions influence considerably the quality of casted steel products, carbon-bonded alumina foam filters are used in secondary metallurgical treatments to remove these particles from steel Melts. In order to attain a significant improvement of the Filtration process, five different carbonaceous spinel compounds from the Fe-/Mg-/Mn-Al-O systems are applied on carbon-bonded alumina filters in this study and investigated with regard of their Filtration efficiency. However, these spinel compounds decompose partially during sintering at 1400 °C under reducing atmosphere, wherefore the resulting coatings contain not only spinel compounds, but also oxidic and metallic components. The subsequent interaction with molten steel leads to the development of multicrystal structures on the filter surface, which stem from interfacial reactions between coating materials, molten steel, and inclusions. As a result of this procedure, a reduction of almost 60% alumina inclusions is measured with the aid of an automatic SEM, whereby spinel compounds from the Fe-Mn-Al-O system achieve highest Filtration efficiencies.

  • Influence of the Wetting Behavior on the Aluminum Melt Filtration
    Light Metals 2019, 2019
    Co-Authors: Claudia Voigt, Lisa Ditscherlein, Eric Werzner, Tilo Zienert, Urs A Peuker, Natalia Sobczak, R. Nowak, Christos G. Aneziris
    Abstract:

    Although it is undisputed that the Filtration of aluminum Melt inside ceramic foam filters is influenced by the wetting behavior between the liquid Melt and the material of the filter coating, experimental proof is still pending. For the present study, the contact angle of an AlSi7Mg alloy on substrates made of Al2O3, MgAl2O4, 3Al2O3·2SiO2 and TiO2 was measured by the sessile drop method at 730 °C using non-contact heating and capillary purification technique. The contact angles were compared with Filtration efficiencies of filters with identical coating composition measured during Filtration trials performed at a pilot casting line. For inclusions smaller than 110 µm, a correlation between contact angle and Filtration efficiency was observed. Furthermore, adhesion forces of alumina inclusions on the four coating materials were experimentally determined using atomic force microscopy in a water-based model system. For inclusions larger than 70 µm, the Filtration efficiency correlates with the measured adhesion force.

Marcus Emmel - One of the best experts on this subject based on the ideXlab platform.

  • functional coatings on carbon bonded ceramic foam filters for steel Melt Filtration
    Steel Research International, 2016
    Co-Authors: Enrico Storti, Steffen Dudczig, Marcus Emmel, Paolo Colombo, Christos G. Aneziris
    Abstract:

    Ceramic foam filters (CFFs) have been used by steel foundries for several years as an effective physical refining solution after the ladle treatment. Recently, new approaches involving “active” and “reactive” coatings applied on the filters have been proposed, in order to improve their efficiency during operation. In this work, two different coating methods are presented. The first exploits the reaction of carbon-bonded alumina–magnesia filters when immersed in a steel Melt at about 1650 °C. In this case, the coating is formed directly during operation: due to the carbothermal reduction of magnesia and dissolution of alumina, in situ spinel formation is observed. This also results in a volume expansion that counteracts the shrinkage of the filter material related to sintering and pyrolysis phenomena. Next, multi-walled carbon nanotubes (MWCNTs) are applied on carbon-bonded alumina filters by means of spray coating to increase the reactivity of the surface. The performance of the coated filters is assessed in comparison to uncoated ones, using a special steel casting simulator under controlled atmosphere. The microscope investigations after 10 and 30 s of immersion indicate a better performance of the MWCNTs-coated filters.

  • Microstructure of Non‐Metallic Inclusions Identified in Cast Steel 42CrMo4 after Metal Melt Filtration by Novel Foam Filters
    steel research international, 2016
    Co-Authors: Anja Weidner, Christos G. Aneziris, Marcus Emmel, Anne Schmidt, Dominik Krewerth, Birgit Witschel, Johannes Gleinig, Olena Volkova, Horst Biermann
    Abstract:

    Non-metallic inclusions can affect significantly the mechanical properties of metallic materials. Mainly for safety relevant components, it is important to reduce size and number of non-metallic inclusions. Recent research work is focused on the development of new reactive, active, and functionalized filters for the reduction of non-metallic inclusions. A detailed knowledge on the genesis of inclusions is essential to improve the entrapment capability. The paper is focused on the microstructure of inclusions formed in cast steel 42CrMo4 after the application of two filter variants. Both, inclusions on the filter surface as well as inclusions in the as-cast steel are investigated using scanning electron microscopy. Their chemical composition and their crystal structure are identified by combined EBSD and EDS measurements. The three-dimensional morphology of the inclusions is analyzed by deep etching technique as well. Finally, the clusters and agglomerates exhibit a quite complex microstructure. Thus, the majority of inclusion clusters consists of alumina, spinel, mullite, MnS, and TiOx. This agrees well to the scenario of the evolution of inclusions described in the literature.

  • microstructure of non metallic inclusions identified in cast steel 42crmo4 after metal Melt Filtration by novel foam filters
    Steel Research International, 2016
    Co-Authors: Anja Weidner, Christos G. Aneziris, Marcus Emmel, Anne Schmidt, Dominik Krewerth, Birgit Witschel, Johannes Gleinig, Olena Volkova, Horst Biermann
    Abstract:

    Non-metallic inclusions can affect significantly the mechanical properties of metallic materials. Mainly for safety relevant components, it is important to reduce size and number of non-metallic inclusions. Recent research work is focused on the development of new reactive, active, and functionalized filters for the reduction of non-metallic inclusions. A detailed knowledge on the genesis of inclusions is essential to improve the entrapment capability. The paper is focused on the microstructure of inclusions formed in cast steel 42CrMo4 after the application of two filter variants. Both, inclusions on the filter surface as well as inclusions in the as-cast steel are investigated using scanning electron microscopy. Their chemical composition and their crystal structure are identified by combined EBSD and EDS measurements. The three-dimensional morphology of the inclusions is analyzed by deep etching technique as well. Finally, the clusters and agglomerates exhibit a quite complex microstructure. Thus, the majority of inclusion clusters consists of alumina, spinel, mullite, MnS, and TiOx. This agrees well to the scenario of the evolution of inclusions described in the literature.

  • Functional Coatings on Carbon‐Bonded Ceramic Foam Filters for Steel Melt Filtration
    steel research international, 2016
    Co-Authors: Enrico Storti, Steffen Dudczig, Marcus Emmel, Paolo Colombo, Christos G. Aneziris
    Abstract:

    Ceramic foam filters (CFFs) have been used by steel foundries for several years as an effective physical refining solution after the ladle treatment. Recently, new approaches involving “active” and “reactive” coatings applied on the filters have been proposed, in order to improve their efficiency during operation. In this work, two different coating methods are presented. The first exploits the reaction of carbon-bonded alumina–magnesia filters when immersed in a steel Melt at about 1650 °C. In this case, the coating is formed directly during operation: due to the carbothermal reduction of magnesia and dissolution of alumina, in situ spinel formation is observed. This also results in a volume expansion that counteracts the shrinkage of the filter material related to sintering and pyrolysis phenomena. Next, multi-walled carbon nanotubes (MWCNTs) are applied on carbon-bonded alumina filters by means of spray coating to increase the reactivity of the surface. The performance of the coated filters is assessed in comparison to uncoated ones, using a special steel casting simulator under controlled atmosphere. The microscope investigations after 10 and 30 s of immersion indicate a better performance of the MWCNTs-coated filters.

  • Development of multi-walled carbon nanotubes-based coatings on carbon-bonded alumina filters for steel Melt Filtration
    Journal of the European Ceramic Society, 2015
    Co-Authors: Enrico Storti, Steffen Dudczig, Marcus Emmel, Paolo Colombo, Christos G. Aneziris
    Abstract:

    Abstract Ceramic foam filters (CFFs) have been used by steel foundries for several years to remove non-metallic inclusions from the metal castings. In order to improve their Filtration efficiency, promising approaches which involve “active” and “reactive” coatings applied on the filters have recently been proposed. In this work, a new coating system containing multi-walled carbon nanotubes (MWCNTs) is presented. A special water-based dispersing technique for carbon nanotubes was developed. Xanthan gum was used both as a dispersing agent and as a rheology modifier for the spraying slurries. The synthetic coal tar pitch Carbores® P was added as a binder for the carbon nanotubes. The coatings were cold-applied on 10 pores per inch (ppi) carbon-bonded alumina filters previously manufactured via the Schwartzwalder process. After drying, the samples were heat treated at 800 °C. The performance of the coated filters was investigated with the aid of a special steel casting simulator in fully-controlled atmosphere.

Steffen Dudczig - One of the best experts on this subject based on the ideXlab platform.

  • impact of spinel forming systems fe mg mn al o as functional coating materials for carbon bonded alumina filters on steel Melt Filtration
    Ceramics International, 2019
    Co-Authors: Benjamin Bock, Steffen Dudczig, Gert Schmidt, Anne Schmidt, Edyta Sniezek, Jacek Szczerba, Christos G. Aneziris
    Abstract:

    Abstract Since solid, non-metallic inclusions influence considerably the quality of casted steel products, carbon-bonded alumina foam filters are used in secondary metallurgical treatments to remove these particles from steel Melts. In order to attain a significant improvement of the Filtration process, five different carbonaceous spinel compounds from the Fe-/Mg-/Mn-Al-O systems are applied on carbon-bonded alumina filters in this study and investigated with regard of their Filtration efficiency. However, these spinel compounds decompose partially during sintering at 1400 °C under reducing atmosphere, wherefore the resulting coatings contain not only spinel compounds, but also oxidic and metallic components. The subsequent interaction with molten steel leads to the development of multicrystal structures on the filter surface, which stem from interfacial reactions between coating materials, molten steel, and inclusions. As a result of this procedure, a reduction of almost 60% alumina inclusions is measured with the aid of an automatic SEM, whereby spinel compounds from the Fe-Mn-Al-O system achieve highest Filtration efficiencies.

  • Impact of spinel forming systems (Fe-/Mg-/Mn-Al-O) as functional coating materials for carbon-bonded alumina filters on steel Melt Filtration
    Ceramics International, 2019
    Co-Authors: Benjamin Bock, Steffen Dudczig, Gert Schmidt, Anne Schmidt, Edyta Sniezek, Jacek Szczerba, Christos G. Aneziris
    Abstract:

    Abstract Since solid, non-metallic inclusions influence considerably the quality of casted steel products, carbon-bonded alumina foam filters are used in secondary metallurgical treatments to remove these particles from steel Melts. In order to attain a significant improvement of the Filtration process, five different carbonaceous spinel compounds from the Fe-/Mg-/Mn-Al-O systems are applied on carbon-bonded alumina filters in this study and investigated with regard of their Filtration efficiency. However, these spinel compounds decompose partially during sintering at 1400 °C under reducing atmosphere, wherefore the resulting coatings contain not only spinel compounds, but also oxidic and metallic components. The subsequent interaction with molten steel leads to the development of multicrystal structures on the filter surface, which stem from interfacial reactions between coating materials, molten steel, and inclusions. As a result of this procedure, a reduction of almost 60% alumina inclusions is measured with the aid of an automatic SEM, whereby spinel compounds from the Fe-Mn-Al-O system achieve highest Filtration efficiencies.

  • functional coatings on carbon bonded ceramic foam filters for steel Melt Filtration
    Steel Research International, 2016
    Co-Authors: Enrico Storti, Steffen Dudczig, Marcus Emmel, Paolo Colombo, Christos G. Aneziris
    Abstract:

    Ceramic foam filters (CFFs) have been used by steel foundries for several years as an effective physical refining solution after the ladle treatment. Recently, new approaches involving “active” and “reactive” coatings applied on the filters have been proposed, in order to improve their efficiency during operation. In this work, two different coating methods are presented. The first exploits the reaction of carbon-bonded alumina–magnesia filters when immersed in a steel Melt at about 1650 °C. In this case, the coating is formed directly during operation: due to the carbothermal reduction of magnesia and dissolution of alumina, in situ spinel formation is observed. This also results in a volume expansion that counteracts the shrinkage of the filter material related to sintering and pyrolysis phenomena. Next, multi-walled carbon nanotubes (MWCNTs) are applied on carbon-bonded alumina filters by means of spray coating to increase the reactivity of the surface. The performance of the coated filters is assessed in comparison to uncoated ones, using a special steel casting simulator under controlled atmosphere. The microscope investigations after 10 and 30 s of immersion indicate a better performance of the MWCNTs-coated filters.

  • Functional Coatings on Carbon‐Bonded Ceramic Foam Filters for Steel Melt Filtration
    steel research international, 2016
    Co-Authors: Enrico Storti, Steffen Dudczig, Marcus Emmel, Paolo Colombo, Christos G. Aneziris
    Abstract:

    Ceramic foam filters (CFFs) have been used by steel foundries for several years as an effective physical refining solution after the ladle treatment. Recently, new approaches involving “active” and “reactive” coatings applied on the filters have been proposed, in order to improve their efficiency during operation. In this work, two different coating methods are presented. The first exploits the reaction of carbon-bonded alumina–magnesia filters when immersed in a steel Melt at about 1650 °C. In this case, the coating is formed directly during operation: due to the carbothermal reduction of magnesia and dissolution of alumina, in situ spinel formation is observed. This also results in a volume expansion that counteracts the shrinkage of the filter material related to sintering and pyrolysis phenomena. Next, multi-walled carbon nanotubes (MWCNTs) are applied on carbon-bonded alumina filters by means of spray coating to increase the reactivity of the surface. The performance of the coated filters is assessed in comparison to uncoated ones, using a special steel casting simulator under controlled atmosphere. The microscope investigations after 10 and 30 s of immersion indicate a better performance of the MWCNTs-coated filters.

  • Development of multi-walled carbon nanotubes-based coatings on carbon-bonded alumina filters for steel Melt Filtration
    Journal of the European Ceramic Society, 2015
    Co-Authors: Enrico Storti, Steffen Dudczig, Marcus Emmel, Paolo Colombo, Christos G. Aneziris
    Abstract:

    Abstract Ceramic foam filters (CFFs) have been used by steel foundries for several years to remove non-metallic inclusions from the metal castings. In order to improve their Filtration efficiency, promising approaches which involve “active” and “reactive” coatings applied on the filters have recently been proposed. In this work, a new coating system containing multi-walled carbon nanotubes (MWCNTs) is presented. A special water-based dispersing technique for carbon nanotubes was developed. Xanthan gum was used both as a dispersing agent and as a rheology modifier for the spraying slurries. The synthetic coal tar pitch Carbores® P was added as a binder for the carbon nanotubes. The coatings were cold-applied on 10 pores per inch (ppi) carbon-bonded alumina filters previously manufactured via the Schwartzwalder process. After drying, the samples were heat treated at 800 °C. The performance of the coated filters was investigated with the aid of a special steel casting simulator in fully-controlled atmosphere.

Paolo Colombo - One of the best experts on this subject based on the ideXlab platform.

  • functional coatings on carbon bonded ceramic foam filters for steel Melt Filtration
    Steel Research International, 2016
    Co-Authors: Enrico Storti, Steffen Dudczig, Marcus Emmel, Paolo Colombo, Christos G. Aneziris
    Abstract:

    Ceramic foam filters (CFFs) have been used by steel foundries for several years as an effective physical refining solution after the ladle treatment. Recently, new approaches involving “active” and “reactive” coatings applied on the filters have been proposed, in order to improve their efficiency during operation. In this work, two different coating methods are presented. The first exploits the reaction of carbon-bonded alumina–magnesia filters when immersed in a steel Melt at about 1650 °C. In this case, the coating is formed directly during operation: due to the carbothermal reduction of magnesia and dissolution of alumina, in situ spinel formation is observed. This also results in a volume expansion that counteracts the shrinkage of the filter material related to sintering and pyrolysis phenomena. Next, multi-walled carbon nanotubes (MWCNTs) are applied on carbon-bonded alumina filters by means of spray coating to increase the reactivity of the surface. The performance of the coated filters is assessed in comparison to uncoated ones, using a special steel casting simulator under controlled atmosphere. The microscope investigations after 10 and 30 s of immersion indicate a better performance of the MWCNTs-coated filters.

  • Functional Coatings on Carbon‐Bonded Ceramic Foam Filters for Steel Melt Filtration
    steel research international, 2016
    Co-Authors: Enrico Storti, Steffen Dudczig, Marcus Emmel, Paolo Colombo, Christos G. Aneziris
    Abstract:

    Ceramic foam filters (CFFs) have been used by steel foundries for several years as an effective physical refining solution after the ladle treatment. Recently, new approaches involving “active” and “reactive” coatings applied on the filters have been proposed, in order to improve their efficiency during operation. In this work, two different coating methods are presented. The first exploits the reaction of carbon-bonded alumina–magnesia filters when immersed in a steel Melt at about 1650 °C. In this case, the coating is formed directly during operation: due to the carbothermal reduction of magnesia and dissolution of alumina, in situ spinel formation is observed. This also results in a volume expansion that counteracts the shrinkage of the filter material related to sintering and pyrolysis phenomena. Next, multi-walled carbon nanotubes (MWCNTs) are applied on carbon-bonded alumina filters by means of spray coating to increase the reactivity of the surface. The performance of the coated filters is assessed in comparison to uncoated ones, using a special steel casting simulator under controlled atmosphere. The microscope investigations after 10 and 30 s of immersion indicate a better performance of the MWCNTs-coated filters.

  • Development of multi-walled carbon nanotubes-based coatings on carbon-bonded alumina filters for steel Melt Filtration
    Journal of the European Ceramic Society, 2015
    Co-Authors: Enrico Storti, Steffen Dudczig, Marcus Emmel, Paolo Colombo, Christos G. Aneziris
    Abstract:

    Abstract Ceramic foam filters (CFFs) have been used by steel foundries for several years to remove non-metallic inclusions from the metal castings. In order to improve their Filtration efficiency, promising approaches which involve “active” and “reactive” coatings applied on the filters have recently been proposed. In this work, a new coating system containing multi-walled carbon nanotubes (MWCNTs) is presented. A special water-based dispersing technique for carbon nanotubes was developed. Xanthan gum was used both as a dispersing agent and as a rheology modifier for the spraying slurries. The synthetic coal tar pitch Carbores® P was added as a binder for the carbon nanotubes. The coatings were cold-applied on 10 pores per inch (ppi) carbon-bonded alumina filters previously manufactured via the Schwartzwalder process. After drying, the samples were heat treated at 800 °C. The performance of the coated filters was investigated with the aid of a special steel casting simulator in fully-controlled atmosphere.

  • in situ spinel formation in al2o3 mgo c filter materials for steel Melt Filtration
    Ceramics International, 2014
    Co-Authors: Marcus Emmel, Christos G. Aneziris, Steffen Dudczig, Francesco Sponza, Paolo Colombo
    Abstract:

    Abstract Spinel-based ceramics for molten steel Filtration were prepared from a mixture of alumina, magnesia and carbon precursors. Samples were analyzed in the form of bars heat treated at different temperatures, or as reticulated foams, after immersion in a steel Melt at 1640 °C. An effect of the composition of the filters on the amount of spinel formed after the heat treatments was observed, which favored the MgO-rich composition. The formation of spinel successfully decreased the disadvantageous shrinkage occurring because of high temperature sintering and pyrolysis phenomena. The presence of carbon affected the rate of spinel formation, and led to additional carbide-based phases after heating at 1600 °C. The immersion of reticulated foams, only pre-heated at 800 °C, into molten steel at 1640 °C led to the virtual transformation of the starting oxides into spinel, and the foams survived well the thermal shock. These materials are therefore well suited for the fabrication of advanced ceramic filters for molten metal Filtration.

  • In situ spinel formation in Al2O3–MgO–C filter materials for steel Melt Filtration
    Ceramics International, 2014
    Co-Authors: Marcus Emmel, Christos G. Aneziris, Steffen Dudczig, Francesco Sponza, Paolo Colombo
    Abstract:

    Abstract Spinel-based ceramics for molten steel Filtration were prepared from a mixture of alumina, magnesia and carbon precursors. Samples were analyzed in the form of bars heat treated at different temperatures, or as reticulated foams, after immersion in a steel Melt at 1640 °C. An effect of the composition of the filters on the amount of spinel formed after the heat treatments was observed, which favored the MgO-rich composition. The formation of spinel successfully decreased the disadvantageous shrinkage occurring because of high temperature sintering and pyrolysis phenomena. The presence of carbon affected the rate of spinel formation, and led to additional carbide-based phases after heating at 1600 °C. The immersion of reticulated foams, only pre-heated at 800 °C, into molten steel at 1640 °C led to the virtual transformation of the starting oxides into spinel, and the foams survived well the thermal shock. These materials are therefore well suited for the fabrication of advanced ceramic filters for molten metal Filtration.

Anne Schmidt - One of the best experts on this subject based on the ideXlab platform.

  • impact of spinel forming systems fe mg mn al o as functional coating materials for carbon bonded alumina filters on steel Melt Filtration
    Ceramics International, 2019
    Co-Authors: Benjamin Bock, Steffen Dudczig, Gert Schmidt, Anne Schmidt, Edyta Sniezek, Jacek Szczerba, Christos G. Aneziris
    Abstract:

    Abstract Since solid, non-metallic inclusions influence considerably the quality of casted steel products, carbon-bonded alumina foam filters are used in secondary metallurgical treatments to remove these particles from steel Melts. In order to attain a significant improvement of the Filtration process, five different carbonaceous spinel compounds from the Fe-/Mg-/Mn-Al-O systems are applied on carbon-bonded alumina filters in this study and investigated with regard of their Filtration efficiency. However, these spinel compounds decompose partially during sintering at 1400 °C under reducing atmosphere, wherefore the resulting coatings contain not only spinel compounds, but also oxidic and metallic components. The subsequent interaction with molten steel leads to the development of multicrystal structures on the filter surface, which stem from interfacial reactions between coating materials, molten steel, and inclusions. As a result of this procedure, a reduction of almost 60% alumina inclusions is measured with the aid of an automatic SEM, whereby spinel compounds from the Fe-Mn-Al-O system achieve highest Filtration efficiencies.

  • Impact of spinel forming systems (Fe-/Mg-/Mn-Al-O) as functional coating materials for carbon-bonded alumina filters on steel Melt Filtration
    Ceramics International, 2019
    Co-Authors: Benjamin Bock, Steffen Dudczig, Gert Schmidt, Anne Schmidt, Edyta Sniezek, Jacek Szczerba, Christos G. Aneziris
    Abstract:

    Abstract Since solid, non-metallic inclusions influence considerably the quality of casted steel products, carbon-bonded alumina foam filters are used in secondary metallurgical treatments to remove these particles from steel Melts. In order to attain a significant improvement of the Filtration process, five different carbonaceous spinel compounds from the Fe-/Mg-/Mn-Al-O systems are applied on carbon-bonded alumina filters in this study and investigated with regard of their Filtration efficiency. However, these spinel compounds decompose partially during sintering at 1400 °C under reducing atmosphere, wherefore the resulting coatings contain not only spinel compounds, but also oxidic and metallic components. The subsequent interaction with molten steel leads to the development of multicrystal structures on the filter surface, which stem from interfacial reactions between coating materials, molten steel, and inclusions. As a result of this procedure, a reduction of almost 60% alumina inclusions is measured with the aid of an automatic SEM, whereby spinel compounds from the Fe-Mn-Al-O system achieve highest Filtration efficiencies.

  • Impact of the Roughness of Alumina and Al2O3–C Substrates on the Adhesion Mechanisms in a Model System
    Advanced Engineering Materials, 2017
    Co-Authors: Lisa Ditscherlein, Christos G. Aneziris, Enrico Storti, Anne Schmidt, Urs A Peuker
    Abstract:

    To improve metal purity by reducing solid and liquid inclusions, intelligent filters with a functionalized surface are studied for an application in metal Melt Filtration. Besides special coatings that increase the attraction of inclusions at the filter surface or react with gases inside the Melt, also the filter roughness might increase the Filtration efficiency. In this study, we investigate the influence of roughness on adhesion forces for hydrophilic and hydrophobic filter surfaces in a water-based model system with an atomic force microscope. In the case of hydrophilic filter substrates, adhesion forces decrease with an increase of roughness whereas on hydrophobic filter surfaces an inverse effect is observed. The primary cause for this is the formation of small cap-shaped bubbles due to poor wetting. To investigate the stability of these bubbles on smooth as well as rough samples of filter material, imaging in contact mode with increasing applied force is performed. On rough surfaces, the bubbles remain stable even at 30–50 nN because of pinning effects.

  • Influence of the Specimen Manufacturing Process on the Strength of Carbon‐Bonded Alumina (Al2O3–C)
    Advanced Engineering Materials, 2017
    Co-Authors: H. Zielke, Martin Abendroth, Anne Schmidt, Meinhard Kuna, Christos G. Aneziris
    Abstract:

    Open cell ceramic foam filters are used for metal Melt Filtration to reduce non-metallic inclusions. A new generation of multifunctional filters made of carbon-bonded alumina is investigated within the Collaborative Research Center CRC 920. These filters have to withstand high thermal and mechanical loads. Motivated by the problem of the filters integrity, a mechanical characterization of the bulk material is necessary. In the Ball On Three Balls Test (B3B) miniaturized disk-shaped specimens are loaded with a spherically tipped punch until failure occurs. With the help of the measured load displacement curve the fracture stress is calculated and analyzed by means of WEIBULL distribution.

  • Microstructure of Non‐Metallic Inclusions Identified in Cast Steel 42CrMo4 after Metal Melt Filtration by Novel Foam Filters
    steel research international, 2016
    Co-Authors: Anja Weidner, Christos G. Aneziris, Marcus Emmel, Anne Schmidt, Dominik Krewerth, Birgit Witschel, Johannes Gleinig, Olena Volkova, Horst Biermann
    Abstract:

    Non-metallic inclusions can affect significantly the mechanical properties of metallic materials. Mainly for safety relevant components, it is important to reduce size and number of non-metallic inclusions. Recent research work is focused on the development of new reactive, active, and functionalized filters for the reduction of non-metallic inclusions. A detailed knowledge on the genesis of inclusions is essential to improve the entrapment capability. The paper is focused on the microstructure of inclusions formed in cast steel 42CrMo4 after the application of two filter variants. Both, inclusions on the filter surface as well as inclusions in the as-cast steel are investigated using scanning electron microscopy. Their chemical composition and their crystal structure are identified by combined EBSD and EDS measurements. The three-dimensional morphology of the inclusions is analyzed by deep etching technique as well. Finally, the clusters and agglomerates exhibit a quite complex microstructure. Thus, the majority of inclusion clusters consists of alumina, spinel, mullite, MnS, and TiOx. This agrees well to the scenario of the evolution of inclusions described in the literature.