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2 2024

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Unconventional Elements in the Gating System and Their Influence on the Melt Flow and Casting Quality

Brůna Marek, Galčík Marek, Medňanský Martin, Kasińska Justyna

Archives of Metallurgy and Materials

2024

Vol. 69, iss. 3

1143--1149

The naturally pressurized gating system appears to be an appropriate solution for reoxidation reduction, but this type of gating system can result in supercritical melt velocity. The paper is focused on the determination of the unconventional elements effect in the gating system on the melt velocity and melt flow and their influence on the mechanical properties and microstructure. In experimental works was observed the influence of dimensioned gate, foam filters with 10 and 30 ppi density, trident gate and combination of trident gate and vortex element. Melt velocity was observed by simulation software and via velocity measurement by contact method in the mold during casting. Melt flow was analyzed by simulation software and water model experiment. Experimental casts have been made for the purpose of evaluating mechanical properties and microstructure determination. The best results were achieved by 30 ppi foam filter.

Research of Hybrid Aluminium Castings with the Use of Porous Cores

Brůna M., Medňanský Martin, Oslanec P.

Archives of Foundry Engineering

2024

Vol. 24, iss. 3

18--24

The paper focuses on the research of hybrid aluminium castings produced by overcasting technology. This is an advanced technology for ensuring the lightness of castings by using the principle of overcasting a core with a porous cellular structure produced by foaming. Process parameters in the foaming phase of the material have a great influence on the resulting porous structure. The article focuses on controlling the influence of pressure during the foaming process on the resulting porosity and evaluating by X-ray tomograph and measuring the relative density. Variants using an initial pressure of 0.3 MPa appear to be the most satisfactory. The challenge of this technology is to ensure adequate bonding of the metals at the interface between the porous core and the solidified metal without penetrating the coating layer. For this reason, the surface treatment of foamed cores with various etchants has been proposed to disrupt the oxide layer on their surface. Macrographs of the uncoated sample and samples etched with 0.5% HF and 10% H3PO4 demonstrated the need for core surface treatment to prevent liquid metal penetration. EDX analysis confirmed the presence of AlPO4 at the core/casting interface in the treated sample.