Lately we encounter still more new applications of metallic foams, as well as possible methods of their manufacture. These metallic materials have specific properties, such as large rigidity at low density, in some cases high thermal conductivity, capability to absorb energy, etc. The work is focused on the preparation of these materials using conventional casting technology, 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 a regular structure made of ferrous and non-ferrous alloys. For thus obtained castings we evaluated the achieved microstructure and mechanical properties, which determine the possible use of these materials. The samples were subjected to compression tests, by which we investigated deformation behaviour of selected materials and determined the value of energy absorption.
The presented paper is focused on the study of refining aluminium-alloy melts. The quality of castings is determined by the basic material, i.e., the input material (furnace charge), its subsequent melting and subsequent metallurgical modifications. To allow the profitability of production, low-quality input materials are currently used, which, although they have the required chemical composition, may contain a large amount of impurities, coming not only from the original input materials, but also from their processing. To allow a cost reduction, in addition to rejected castings, the residues of gating and chipping from the machining are used as charge materials in foundries. However, the melt thus prepared is heavily contaminated with gases and inclusions.The aim of the research was, therefore, to verify the use of graphite rotors functioning as degassing units for refining aluminium melts. The experiments were conducted under laboratory and pilot-plant conditions using the plant equipment. The refining efficiency was monitored with respect to the type and shape of the graphite rotor and the refining medium used. The achieved purity of the resulting melt was evaluated to establish the density index and the final cast microstructure.
The aim of this paper is to summarize the possibilities of foundry methods for the production of metallic foams. At present, there are a number of production technologies for this interesting material, to which increasing attention has been paid in recent years. What is unique about metallic foams is the combination of their physical and mechanical properties. As part of our research, we designed and verified four main methods of metallic foam production by the foundry technology, whose products are metallic foam castings with regular and irregular arrangements of internal cavities. All these methods use materials and processes commonly used in conventional foundry technologies. The main idea of the research is to highlight such technologies for the production of metallic foams that could be provided by manufacturing companies without the need to introduce changes in production. Moreover, foundry methods for the production of metallic foams have the unique advantage of being able to produce even complex shaped parts and can thus be competitive compared to today’s established technologies, the output of which is usually only a semi-finished product for further processing. This fact was the main motivation for the research.
Metallic foams are the materials, the research of which is still ongoing, with a broad applicability in many different areas (e.g., automotive industry, building industry, medicine, etc.). These materials have interesting potentials due to a combination of properties, which are, on the one hand, related to their metallic character and, on the other hand, to the porous structure. Since the discovery of porous metallic materials numerous methods of production have been developed. This work deals with the optimization of the foundry method for the manufacture of metallic foams using the evaporable polymeric pattern. This technology was used for the manufacture of metallic foams with an irregular cell structure and with fully open pores. Attention, in the experimental part, is devoted particularly to the chosen moulding material -plaster. We checked the suitably of the proposed procedure of manufacturing a plaster mould, the drying process and the subsequent annealing that significantly influence the final properties of the mould and, therefore, the quality of the resulting casting of the metallic foam. Keywords: metallic foams, casting, irregular cell structure, plaster, annealing Kovinske pene so materiali, ki se {e preiskujejo in imajo {iroko podro~je uporabnosti na razli~nih podro~jih (npr. avtomobilska industrija, gradbena industrija, medicina in podobno). Ti materiali so perspektivni zaradi kombinacije lastnosti, ki imajo po eni strani kovinske lastnosti, po drugi pa porozno strukturo. Od odkritja poroznih kovinskih materialov so se razvile {tevilne metode njihove izdelave. Delo obravnava optimizacijo livarske metode izdelave kovinske pene z uporabo izparljivega polimernega modela. Ta tehnologija je bila uporabljena za izdelavo kovinske pene z nepravilno celi~no strukturo in popolnoma odprtimi porami. V eksperimentalnem delu je pozornost usmerjena v izbiro mavca kot materiala za model. Preverjen je bil predlagani postopek izdelave mav~nega modela, postopka su{enja in`arjenja, ki imajo najve~ji vpliv na kon~ne lastnosti modela in na kvaliteto ulivanja kovinske pene.
2 SaM Nové Ransko, s.r.o., Nové Ransko 234, 582 63 @dírec nad Doubravou, Czech Republic Prejem rokopisa -The presented work was devoted to the development of the production processes for metallic foams, which were based on conventional casting technologies. The use of the standard casting processes and standard materials made it possible to identify the range of metallic foams amongst affordable materials, thereby making a full use of their application potentials. The experimental part was focused on the development and subsequent optimization of the casting processes for manufacturing cast metallic foams with irregular inner-cell structures, and especially on the development of the technology of infiltrating molten metal into a mold cavity filled with precursors.Avtorji predstavljajo razvoj procesa izdelave kovinskih pen, ki temelji na konvencionalnih tehnologijah litja. Zaradi uporabe standardne livarske prakse in materialov spadajo kovinske pene med dostopne materiale, in tako je mogo~poln izkoristek njihovega potenciala. Eksperimentalni del {tudije je bil osredoto~en na razvoj in takoj{njo optimizacijo livarskega postopka izdelave kovinskih pen z nepravilno notranjo celi~no strukturo. Delo je bilo {e posebej osredoto~eno na razvoj tehnologije infiltracije kovinske taline v votlino orodja, ki je bila pred tem napolnjena s predhodno surovino (prekurzorjem).
Metallic foams are materials that are subject of an ongoing research with the broad applicability in many different areas (e.g. automotive industry, building industry, medicine, etc.). These metal materials contain in their structure artificially created pores. These pores give them specific properties, such as: large rigidity at low density, high thermal conductivity, capability to absorb energy, etc. Since the discovery of porous metallic materials numerous methods of production have been developed. The aim of the paper is to introduce effective casting methods of manufacturing of metallic foams, namely cast metal filters from the aluminum alloy. Research deals with investment casting with use of pattern made of polymeric foam, which is used for production of metallic foam with open pores. The main disadvantage of this procedure consists in removing the mould material without damaging the fine structure of the cast filter. Plaster is used as the mould material and the most important result of this paper is the presentation of the effective procedure of plaster removal from the porous structure of cast filters.Keywords: metallic foam; aluminum foam; manufacturing of metal foam; cast metal filter Piany metalowe są przedmiotem wielu badań gdyż znajdują szerokie zastosowanie w wielu dziedzinach np. produkcji samochodów, budownictwie czy w medycynie. W swojej strukturze zawierają sztucznie wytworzone pory, zapewniające uzyskanie specyficznych właściwości jak duża wytrzymałość, niewielka gęstość, wysokie przewodnictwo cieplne zdolność do absorpcji energii itp. Od czasu wynalezienia porowatych materiałów metalowych opracowano wiele metod ich wytwarzania. Celem opracowania jest wprowadzenie efektywnych metod odlewniczych produkcji pian metalowych, szczególnie ze stopów glinu. Studium zajmuje się precyzyjną metodą odlewania przy zastosowaniu modelu wykonanego z piany polimerowej stosowanej w produkcji piany z otwartymi porami. Główna niedogodność metody polega na trudności usuwania materiału formierskiego, bez naruszenia delikatnej struktury odlewanego filtra. Jako materiał formierski stosuje się gips i najważniejszym wynikiem pracy jest przedstawienie efektywnej procedury usuwania gipsu z porowatej struktury odlanego filtra.
The aim of this study is the evaluation of the parameters of core mixtures using different binder systems with regard to the collapsibility of cores after casting and the resulting product quality of castings reflecting surface requirements based on non-ferrous alloys. The research compares organically bonded core mixtures based on phenol-formaldehyde resins for the production of cores with the shell molding (resin coated sand), currently used in the production of aluminum alloy castings in the Brembo Czech s.r.o., and mixtures using innovative inorganic binder systems based on geopolymers; GEOPOL® W. The aim of the research is to compare the advantages and disadvantages of these binder systems in order to evaluate the potential of inorganically bonded mixtures to replace organically bonded mixtures, which would lead to a significant reduction in the environmental impacts of industrial production of castings.
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