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Abstract

Metallic foams are materials of which the research is still on-going, with the broad applicability in many different areas (e.g. automotive

industry, building industry, medicine, etc.). These metallic materials have specific properties, such as large rigidity at low density, high

thermal conductivity, capability to absorb energy, etc. The work is focused on the preparation of these materials using conventional casting

technology (infiltration method), which ensures rapid and economically feasible method for production of shaped components. In the

experimental part we studied conditions of casting of metallic foams with open pores and irregular cell structure made of ferrous and nonferrous

alloys by use of various types of filler material (precursors).

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Authors and Affiliations

P. Lichý
I. Kroupová
F. Radkovský
V. Bednářová
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Abstract

Internal structure of metal foams is one of the most important factors that determine its mechanical properties. There exists a number of methods for studying the nature of the inner porous structure. Unfortunately most of these processes is destructive and therefore it is not possible to reuse the sample. From this point of view, as a suitable method seems to be the ability of using the so-called X-ray microtomography (also micro-CT). This is a non-destructive methodology used in a number of fields (industry, science, archaeology, medicine) for a description of the material distribution in the space (e.g. pores, fillers, defects, etc.). In principle, this technology works on different absorption of X-ray radiation by materials with changing proton number. The contribution was worked out in collaboration with experts from the Faculty of Electrical Engineering and Computer Science of the VŠB-Technical University of Ostrava and it is focused on the analysis of internal structure of the metal foam casting with irregular arrangement of internal pores by using micro-CT. The obtained data were evaluated in the commercial software VGStudio MAX 2.2 and in the FOTOMNG system. For the evaluation of these data a new specialized module was introduced in this system. Several methods of pre-processing the image was prepared for the measurement. This preliminary processing consists, for example, from a binary image thresholding for better diversity between the internal porosity and the material itself or functions for colour inversion.

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Authors and Affiliations

I. Kroupová
P. Lichý
L. Ličev
J. Hendrych
K. Souček
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Abstract

The paper deals with the possibilities of influencing the final microstructure of aluminium alloy castings by changing the external conditions of crystallization and solidification. Aluminum alloys, especially Al-Si alloys, are nowadays one of the most used non-ferrous metal alloys, especially due to their mass application in the automotive field. It is in this industry that extreme emphasis is placed on the quality of cast parts with regard to safety. For this reason, a key production parameter is the mastery of the control of the resulting microstructure of the castings and the associated internal quality, which is subject to high demands defined by international standards. The aim of the experiment of this paper is to evaluate the effect of different preheating of the metal mould on the resulting structure and hardness of test castings made of AlSi7Mg0.3 material. The hardness measurement will be evaluated on a hardness tester. The parameter SDAS, Microporosity, Content of excluded eutectic will be evaluated. Dependencies will be found and plotted.
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Authors and Affiliations

F. Radkovský
1
ORCID: ORCID
M. Gawronová
1
ORCID: ORCID
I. Kroupová
1
ORCID: ORCID

  1. VSB - Technical University of Ostrava, Czech Republic
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Abstract

This paper presents an overview of a research on six practical cases that were solved in a precise casting company where parts are cast by the mean of the low-wax casting method (investment casting) in order to decrease poor quality production. The steel cast parts production technology by the lost-wax method requires the detailed work procedures observation. On the base of statistical processing data of given types of casting products, it was possible to assess the significance of each particular checking events by using the statistical hypothesis testing. The attention was focused on wax and ceramic departments. The data in technological flow were compared before and after the implementation of the change and statistical confirmative influences were assessed. The target consisted in setting such control manners in order to get the right conditions for decreasing poor quality parts. It was evidenced that the cast part defect cause correct identification and interpretation is important.
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Bibliography

[1] Elbel, T., Havlíček, F., Jelínek, P., Levíček, P., Rous, J., Stránský, K. (1992). Defects of iron alloy castings (classification, causes and prevention). Brno: MATECS. (in Czech).
[2] Nenadál, J. (2004). Measurement in quality management systems. Praha: Management Press. (in Czech).
[3] Lakomá, R., Čamek, L. (2013). Possibilities for quality control of casting products . In 22nd International Conference on Metallurgy and Materials, Metal, 15th-17th May 2013 (p. 40). Brno, Czech Republic, TANGER s. r. o. Ostrava. ISBN 978-80-87294-39-0.
[4] Plura, J. (2001). Planning and continuous quality improvement. Praha: Computer Press. (in Czech).
[5] Čamek, L., Lichý, P., Kroupová, I., Duda, J., Beňo, J., Korbáš, M., Radkovský, F., Bliznyukov, S. (2016). Effect of cast steel production metallurgy on the emergence of casting defect. Metalurgija. 55(4), 701-704. ISSN 0543-5846.
[6] Jezierski, J., Dojka, K., Kubiak, K., et al. (2016). Experimental approach for optimization of gating system in castings. In 25th International Conference on Metallurgy and Materials, Metal 25th-27th May (pp. 104-109). Brno, Czech Republic, TANGER s. r. o. Ostrava. ISSN 0543-5846.
[7] Jaromin, M., Dojka, R., Jezierski, J., Dojka, M. (2019). Influence of Type and Shape of the Chill on Solidification Process of Steel Casting. Archives of Foundry Engineering. 19(1), 35-40. ISSN (1897-3310).
[8] Richtarech, L., Bolibruchova, D.; Bruna, M.; Caiss, J. (2015). Influence of Nickel Addition on Properties of Secondary AlSi7Mg0.3 Alloy‎. Archives of Foundry Engineering. 15(2), 95-98. ISSN (1897-3310). DOI: 10.1515/afe-2015-0046.
[9] Merta, V., Lána, I. (2020). Manufacturing of Cast-metal Sponges from Copper Alloys. Materiali in Technologije. 54(1), 117-119. DOI: 10.17222/mit.2019.159.
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Authors and Affiliations

R. Lakomá
1
L. Čamek
2
P. Lichý
2
ORCID: ORCID
I. Kroupová
1
ORCID: ORCID
F. Radkovský
1
ORCID: ORCID
T. Obzina
1

  1. VSB - Technical university of Ostrava, Czech Republic
  2. Brno University of Technology, Czech Republic
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Abstract

This paper describes the technology for the production of precursors (space holder material) used to form the complex internal structure of cast metal foam. The precursor material must exhibit sufficient refractoriness, resist contact with liquid metal and at the same time should exhibit good collapsibility after casting. With regard to the greening of foundry production, the focus of this paper was on materials that could exhibit the above properties and at the same time do not have a negative impact on the environment. In this paper, the technology for the production of spherical precursors from a self-hardening mixture with a geopolymer-based binder system is described and verified. The motivation for the choice of material and all the sub-steps of the process – molding into the core box, tumbling, including the necessary accompanying tests of the mechanical properties of the core mixture being verified – are described.
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Authors and Affiliations

I. Kroupová
1
ORCID: ORCID
M. Bašistová
1
ORCID: ORCID
P. Lichý
1
ORCID: ORCID
V. Merta
1
ORCID: ORCID
F. Radkovský
1
ORCID: ORCID
J. Jezierski
2
ORCID: ORCID

  1. VŠB-Technical University of Ostrava, Faculty of Materials Science and Technology, Department of Metallurgical Technologies, 17. Listopadu 2172/15, Ostrava-Poruba, Czech Republic
  2. Silesian University of Technology, Faculty of Mechanical Engineering, Department of Foundry Engineering, 2 Towarowa Str., 744-100 Gliwice, Poland

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