Filtration Efficiency of Functionalized Ceramic Foam Filters for Aluminum Melt Filtration

Voigt, Claudia; Jäckel, Eva; Taina, Fabio; Zienert, Tilo; Salomon, Anton; Wolf, Gotthard; Aneziris, Christos G.; Brun, Pierre Le

doi:10.1007/s11663-016-0869-5

Cited by 44 publications

(33 citation statements)

References 13 publications

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“…For CFFs with a nominal pore count of 30 PPI, as used for the continuous casting of aluminum, the filtration efficiency for inclusions of 20-30 mm size was reported to range between 75 and 87%, [2] which is still considered unsatisfactory, if one poses highest requirements on the melt cleanliness. It is evident that a further increase in h could be achieved by employing filters with higher pore count, [3] that is, smaller pores, or with greater dimensions, although at the cost of permeability and material consumption, respectively.…”

Section: Introductionmentioning

confidence: 99%

Influence of Foam Morphology on Effective Properties Related to Metal Melt Filtration

et al. 2017

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In this article, a numerical study on the sensitivity, related to the performance of open-cell foams used for the depth filtration of liquid metals, on two characteristic morphological properties is presented. Therefore, simulations of fluid flow and particle transport inside an artificial foam structure are carried out, whose porosity and strut shape is varied within a certain expected range. For comparison purposes, however, the simulations are also performed for three typical ceramic foam filters (CFF) with pore densities of 20 and 30 PPI, whose geometries are obtained from CT scans. In order to allow for a comparison between the different structures, a reference length is introduced that relies upon the actual ratio of pores per volume. The evaluation is mainly based on the comparison of the hydraulic tortuosity, the viscous and the inertial permeability coefficients as well as the initial filtration coefficient for alumina inclusions, with their size ranging from of 10 to 40 mm at process conditions typically encountered during the aluminum filtration. It is shown that the ratio of filtration coefficient and pressure drop increases with the porosity, while the material distribution between the struts and the joints is less influential. Finally, the article also provides information on the anisotropy of CFFs and on the transition behavior from steady to unsteady flow in open-cell foams.

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Section: Introductionmentioning

confidence: 99%

Influence of Foam Morphology on Effective Properties Related to Metal Melt Filtration

et al. 2017

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“…For the casting experiment, a resistance tilting furnace was employed in order to melt 730 kg AlSi7Mg0.3 ingots at 750 C. [16,17] A specific ceramic foam filter was inserted in the filtration box and was preheated to 650 C. [16,17] At the entrance of the filter, the melt temperature was recorded to be 735 C for the considered trial. [17] The physical properties of the liquid AlSi7Mg0.3 [18] and the alumina filter [19,20] at 700 C are provided in Table 1.…”

Section: Experimental Process Conditionsmentioning

confidence: 99%

“…In detail, alumina (Al 2 O 3 , 20-150 mm), spinel (MgAl 2 O 4 , 20-60 mm), mullite (3Al 2 O 3 2SiO 2 , 20-60 mm), and silicon carbide (SiC, 20-50 mm) particles were introduced in known quantities and in equal proportions. [16,17] The inclusions were added to the melt, which was then mechanically stirred inside the furnace in order to achieve an even particle concentration, before executing the casting operation. [16,17] The filtration efficiency was determined by employing two liquid metal cleanliness analyzers (LiMCA) in the casting line before and after the filter.…”

Section: Experimental Process Conditionsmentioning

confidence: 99%

“…[16,17] The inclusions were added to the melt, which was then mechanically stirred inside the furnace in order to achieve an even particle concentration, before executing the casting operation. [16,17] The filtration efficiency was determined by employing two liquid metal cleanliness analyzers (LiMCA) in the casting line before and after the filter. [16,17] Inclusions of size in the range 20-110 mm were detected, where the particles, belonging to different size classes of equal width, could be distinguished.…”

Section: Experimental Process Conditionsmentioning

confidence: 99%

“…[16,17] The filtration efficiency was determined by employing two liquid metal cleanliness analyzers (LiMCA) in the casting line before and after the filter. [16,17] Inclusions of size in the range 20-110 mm were detected, where the particles, belonging to different size classes of equal width, could be distinguished. [16,17] In the present investigation, however, the filtration efficiency for particles belonging only to the smallest size bin was considered.…”

Section: Experimental Process Conditionsmentioning

confidence: 99%

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Non‐Isothermal Simulations of Aluminum Depth Filtration

Demuth

Werzner²,

Mendes

et al. 2017

Adv Eng Mater

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The present article addresses the modeling issues, related to the numerical simulation of aluminum depth filtration inside a real filter section in presence of non-negligible temperature variation. The filter structure is obtained by digitizing the computed tomography (CT) scanned data of a characteristic ceramic foam filter. The modeling takes the process conditions of a filtration trial in a pilot casting line into account. The incompressible flow of liquid aluminum is solved by the lattice Boltzmann method (LBM) and the heat transfer is solved by the finite volume method (FVM). The temperature dependences of the viscosity and the density of liquid metal are specifically considered. Although the consideration of buoyancy force significantly affects the fluid flow, the temperature-dependent viscosity plays only a minor role. A Lagrangian tracking of particles is performed for modeling the filtration of inclusions. In accordance with the depth filtration theory, the computational results confirm an exponential decrease in the particle concentration with the filter depth. The overall filtration efficiency is found to remain almost unaffected by both buoyancy and temperature-dependent viscosity. Using the numerically determined filtration coefficient, the filtration efficiency is extrapolated for a real filter of larger length, although the experimental data are underpredicted.

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An Approach Toward Numerical Investigation of the Mechanical Behavior of Ceramic Foams during Metal Melt Filtration Processes

et al. 2017

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This article demonstrates an approach for the numerical modeling of open cell ceramic foams, in order to investigate the thermo-mechanical behavior during metal melt filtration processes. The described methods include the creation of the geometric models, the fluid-dynamic simulations of the melt flow using the lattice boltzmann method, and finite element simulations of the ceramic foam under general loads. The paper mainly focuses on the representative geometry generation process, such that the modeled geometry replicates the real foam as far as possible, since high quality models are essential for the quantitative analyses to be reliable. The present parametric studies demonstrate the manner, in which the foam properties may be influenced by changing the geometric and the topological properties, in order to improve the behavior during filtration processes.

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Filtration Efficiency of Functionalized Ceramic Foam Filters for Aluminum Melt Filtration

Cited by 44 publications

References 13 publications

Influence of Foam Morphology on Effective Properties Related to Metal Melt Filtration

Influence of Foam Morphology on Effective Properties Related to Metal Melt Filtration

Non‐Isothermal Simulations of Aluminum Depth Filtration

An Approach Toward Numerical Investigation of the Mechanical Behavior of Ceramic Foams during Metal Melt Filtration Processes

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