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Influence of Intensification Factors on Quality of Fe Agglomerates Made with Alternative Fuel

Semanová Z., Legemza J., Hrubovčáková M., Findorák R., Fröhlichová M.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 4

1853--1857

EN

Currently is the biggest problem of metallurgical companies the increase of fossil fuel prices and strict environmental regulations. As a result of this, companies must look for alternatives that would reduce the amount of fossil fuels and reduce emissions. Wood sawdust has huge energy potential, which can be used in the process of agglomerate production. This type of energy is locally available, has some similar properties as fossil fuels and is economically advantageous. For these reasons, experimental study using laboratory agglomeration pan was realized to study the possibility of agglomerate production with a mixed fuel. Experimental results show the viability of mixed fuel use in the agglomeration process, but also show significant possibility for improvement. The maximum acceptable substitution ratio, which corresponds to qualitatively suitable agglomerate is 20% of pine sawdust. Based on the realized experiments and the obtained results we have acceded to the intensification of the agglomeration process with an objective to increase the amount of added substitution fuel while maintaining the required quality of agglomerate.

2

Technological Properties of Moulding Sands with Geopolymer Binder for Aluminium Casting

Vaskova I., Conev M., Hrubovčáková M.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 4

45--49

EN

The use of environmentally friendly inorganic binders and new technologies for cores production is widely discussed topic in recent years. This paper contains information about new hot curing process for core making with alumina-silicate based inorganic binders – geopolymers. Main differences between hot cured geopolymers and hot cured alkali silicate based inorganic binders are discussed. The main objective of this research paper was to investigate basic technological properties of geopolymer binder system such as strength, compaction, storage ability and knock-out properties. For this purpose, three mixtures with different powder additives were prepared and tested in laboratory conditions using specific methods. Strength properties evaluation showed sufficient levels as well as knock-out properties measurement, even with additives B and C originally designed for the use with alkali silicate based two component binder systems. Additives B and C were considered compatible with geopolymer binders after casting production trial results. Storage ability of geopolymers seems to be more sensitive than of alkali silicate based binders in the same tested conditions. Mixtures with geopolymer binder showed 20% more decrease of strength compared to alkali silicate binders after 24 hours in conditions of 25 °C and 65 %RH.

3

Influence of additives in core-forming mixture

Vasková I., Hrubovčáková M., Conev M.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 1

335--338

EN

In recent years, ingredients, also known as additives, which appreciably affect the quality of the casting surface, come to the fore. Additives - lower the temperature at which SiO2 (major component of silica sand) begins to soften and create a melt on the surface of the grains, increase the reactivity and decrease the temperature of a transition to tridimite and cristobalit. These passages support the increase of volume of subsurface sand stress and the tension for the formation of burrs and other casting defects on the surface of the core or the mold. Nowadays, as a great emphasis is put on the quality of the casts, it is therefore necessary to pay attention to these additives, which can effectively reduce the labor intensity in the production of castings and ensure a quality surface of castings.

4

Decoring Behaviour of Chosen Moulding Materials with Alkali Silicate Based Inorganic Binders

Conev M., Vasková I., Hrubovčáková M., Hajdúch P.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2A

703--706

EN

This paper contains basic information about new processes for cores for cylinder heads production with alkali silicate based inorganic binders. Inorganic binders are coming back to the foreground due to their ecologically friendly nature and new technologies for cores production and new binder systems were developed. Basically these binder systems are modified alkali silicates and therefore they carry some well-known unfavourable properties with their usage. To compensate these disadvantages, the binder systems are working with additives which are most often in powder form and are added in the moulding material. This paper deals with decoring behaviour of different moulding sands as well as the influence of chosen additives on knock-out properties in laboratory terms. For this purpose, specific methods of specimen production are described. Developed methods are then used to compare decoring behaviour of chosen sands and binder systems.

5

Opening Material as the Possibility of Elimination Veining in Foundries

Hrubovčáková M., Vaskova I., Benkova M., Conev M.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 3

157--161

EN

The main bulk density representation in the molding material is opening material, refractory granular material with a particle size of 0.02 mm. It forms a shell molds and cores, and therefore in addition to activating the surface of the grain is one of the most important features angularity and particle size of grains. These last two features specify the porosity and therefore the permeability of the mixture, and thermal dilatation of tension from braking dilation, the thermal conductivity of the mixture and even largely affect the strength of molds and cores, and thus the surface quality of castings. Today foundries, which use the cast iron for produce of casts, are struggling with surface defects on the casts. One of these defects are veining. They can be eliminated in several ways. Veining are foundry defects, which arise as a result of tensions generated at the interface of the mold and metal. This tension also arises due to abrupt thermal expansion of silica sand and is therefore in the development of veining on the surface of casts deal primarily influences and characteristics of the filler material – opening material in the production of iron castings.

6

Dimensional Changes, Microstructure, Microhardness Distributions And Corrosion Properties Of Iron And Iron-Manganese Sintered Materials

Kupková M., Hrubovčáková M., Zeleňák A., Sułowski M., Ciaś A., Oriňáková R., Morovská Turoňová P., Žáková K., Kupka M.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2A

639--642

EN

Iron samples and Fe-Mn alloys with Mn content of 25 wt.% and 30 wt.% were prepared by blending, compressing and sintering with the aim to study their dimensional changes, microstructure, microhardness distribution and primarily the electrochemical corrosion behaviour in a simulated body environment. The light microscopy (LM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and micro-hardness measurements revealed a microheterogeneous multiphase structure of sintered Fe-Mn samples. The potentiodynamic tests have demonstrated that the corrosion rates of such Fe-Mn alloys immersed in Hank’s solution were higher than those for a pure iron, and also higher than the rates reported for homogeneous Fe-Mn alloys.

PL

Próbki żelazne oraz stopy Fe-Mn, zawierające 25 i 30% mas. Mn, przeznaczone na biomateriały, zostały przygotowane na drodze mielenia, prasowania oraz spiekania w celu zbadania ich zmian wymiarowych, mikrostruktury, rozkładu mikrotwardości oraz odporności korozyjnej w skumulowanych w warunkach laboratoryjnych, panujących w ciele człowieka. Badania z wykorzystaniem mikroskopii optycznej i skaningowej, wraz z EDX oraz pomiary mikrotwardości ujawniły mikroniejednorodność wielofazowej struktury spiekanych stopów Fe-Mn. Testy potentiometryczne wykazały, że współczynniki korozji spieków Fe-Mn były wyższe niż spieków wykonanych z czystego żelaza oraz z jednorodnych stopów Fe-Mn.

7

Influence of Technological Parameters of Furane Mixtures on Shrinkage Creation in Ductile Cast Iron Castings

Vasková I., Hrubovčáková M., Eperješi Š., Malik J.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 3

1037--1040

EN

Ductile cast iron (GS) has noticed great development in last decades and its boom has no analogue in history humankind. Ductile iron has broaden the use of castings from cast iron into areas, which where exclusively domains for steel castings. Mainly by castings, which weight is very high, is the propensity to shrinkage creation even higher. Shrinkage creation influences mainly material, construction of casting, gating system and mould. Therefore, the main realized experiment was to ascertain the influence of technological parameters of furane mixture on shrinkage creation in castings from ductile iron. Together was poured 12 testing items in 3 moulds forto determine and compare the impact of various technological parameters forms the propensity for shrinkage in the casting of LGG.

PL

W ostatnich latach obserwuje sie intensywny wzrost produkcji odlewów z żeliwa sferoidalnego. Dotyczy to także zastępowania tym tworzywem odlewów staliwnych. W przypadku masywnych odlewów szczególnie duże znaczenie odgrywa przebieg skurczu tworzywa. Powstawanie skurczu wiąże się z materiałem odlewu, jego konstrukcja, układem wlewowym oraz materiałem formy. Celem badan zaprezentowanych w artykule jest ocena wpływu właściwości technologicznych formy na podstawie skurczu. Odlano 12 kształtek w 3 formach, aby ocenić wpływ jakości formy na skurcz odlewów z żeliwa sferoidalnego.

8

Ecological Binding Material of First Generation

Vasková I., Hrubovčáková M.

Archives of Foundry Engineering

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2014

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Vol. 14, iss. 2

123--128

EN

Bentonite is clay rock, which is created by decomposition of vulcanic glass. It is formed from mixture of clay minerals of smectite group, mainly montmorillonite, beidellite and nontronite. Its typical characteristics is, that when in contact with water, it intensively swells. First who used this term was W.C. Knight in 1887. The rock had been named after town Fort Benton in American state Montana. For its interesting technological properties and whiteness has wide technological use. Bentonite is selectively mined and according to its final use separately modified, which results in high quality product with specific parameters. In the beginning of 21st century belong bentonite moulding mixtures in foundry to always perspective. Mainly increased ratio of ductile cast iron castings production cannot be ensured without the need of quality bentonite. Great area of scope remains to further research of moulding materials, which return also to bentonite producers.