Wyniki wyszukiwania - Biblioteka Nauki

1

Synthesis of SiO2 nanopowders containing quartz and cristobalite phases from silica sands

100%

Munasir Z. , Triwikantoro T. , Zainuri M. , Darminto D.

Materials Science Poland

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2015

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tom Vol. 33, No. 1

47--55

EN

In this study, extraction and synthesis of SiO2 nanoparticles from silica sands have been conducted by means of two different methods, i.e. dry method (method 1) and hydrothermal process (method 2). The basic difference between the two methods is in the extraction step. The two methods were compared in terms of being more efficient, economical, and superior in obtaining SiO2 nanoparticles. The SiO2 nanoparticles were characterized in terms of phase purity, crystallinity, Si–O functional bonding as well as particles size and morphology. The most interesting fact in this study was the formation of both quartz and cristobalite phases within all prepared SiO2 nanoparticles.

2

Alternative Evaluation of the Properties of the Silica Sands

88%

Beňo J. , Mikšovský F. , Jelinek P. , Konečná K. , Smysl P.

Archives of Metallurgy and Materials

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2014

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tom Vol. 59, iss. 2

735--738

EN

For the evaluation of silica sands, which belongs to the most employed sands of foundry molding mixtures, there are a number of methods and techniques to characterize their quality. This implies good knowledge of their strengths and weaknesses. However, a small proportion of published results are dedicated to the impact of transport on transport routes in the foundry and the processes of dry reclamation on the properties of the silica sands, in particular on changes to the granulometry and the formation of undesirable dust sands shares, which significantly affect the properties of the sand mixture. The aim of this contribution is the evaluation of inclination of the silica sand to crush (the formation of dust, change the granulometry) according to the newly developed methodology with regard to its nature of sand (genesis, the shape of the grains, the character of the surface).

PL

Piaski kwarcowe stanowią podstawowe tworzywo na osnowę mas formierskich i rdzeniowych. Stąd istnieje bardzo wiele metod charakteryzujących ich jakość, co umożliwia poznanie ich zalet i wad. Mało jest jednak prac opisujących wpływ systemów transportowych odlewni oraz systemów suchej regeneracji mas na zmianę ich składu granulometrycznego oraz zawartości frakcji pylastych na właściwości mas. Celem niniejszej pracy jest ocena skłonności piasku kwarcowego do rozkruszania, (tworzenia frakcji pyłowych i zmianie granulometrii) według nowo opracowanej metodyki uwzględniającej charakterystyczne cechy piasku wynikające z jego pochodzenia, kształty ziaren i charakteru powierzchni.

3

Influence the Composition of the Core Mixture to the Occurrence of Veinings on Castings of Cores Produced by Cold-Box-Amine Technology

88%

Delimanová P. , Vasková I. , Bartošová M. , Hrubovčáková M.

Archives of Metallurgy and Materials

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2023

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tom Vol. 68, iss. 3

947--953

EN

The main problem in the cores production by cold-box method is the occurence of surface defects due to the tension generated by thermal expansion of the silica sand. One of the possibilities of eliminination is exchange of silica sand from another location. Another interesting factor is the type of used binder and its amount. However, even these measures donʹt guarantee sufficient quality. Foundries most often solve this problem by adding expensive additives to the core mixture. Foundries may have a dilemma in choosing the right additive. The aim of this paper was to investigate the effect of silica sand from two different locations, the effect of dosing the amount of binder and the addition of several types of commonly available additives on the quality of casting cavities. For this purpose, a total of 11 differently composed core sand mixtures were prepared, but only one of these mixtures was successful.

4

Investigations of protective coatings for castings of high-manganese cast steels

63%

Holtzer M. , Bobrowski A. , Drożyński D. , Mocek J.

Archives of Foundry Engineering

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2013

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tom Vol. 13, iss. 1

39--44

EN

When cast steel castings are made in moulding sands on matrices of high-silica sand, which has a low fire resistance the problem of the so-called chemical penetration is distinctly visible. Whereas this effect appears to a small degree only when moulding sand matrices are of chromite, zircon or olivine sands. Therefore in case of making castings of high-manganese cast steel (e.g. Hadfield steel) sands not containing free silica should be applied (e.g. olivine sand) or in case of a high-silica matrix protective coatings for moulds and cores should be used. Two protective coatings, magnesite alcoholic (marked as coating 1 and coating 2) originated from different producers and intended for moulds for castings of the Hadfield steel, were selected for investigations. Examinations of the basic properties were performed for these coatings: viscosity, thermal analysis, sedimentation properties, wear resistance. In order to estimate the effectiveness of protective coatings the experimental castings were prepared. When applying coating 1, the surface quality of the casting was worse and traces of interaction between the casting material (cast steel) and the coating were seen. When protective coating 2 was used none interactions were seen and the surface quality was better.

5

Moulding sands grain size investigations by means of the laser method of measurement

63%

Dańko R. , Holtzer M.

Archives of Metallurgy and Materials

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2010

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tom Vol. 55, iss. 3

787-794

EN

The knowledge of the grain size distribution in polydispersive materials, which are among others, moulding sands used in foundry industry, is essential for the proper interpretation of results of technological processes investigations influencing, in consequence, the castings quality. Current tests of moulding sands grain size are performed by the sieve analysis methods according to the binding standards in the individual country. Those standards require recalculations of results obtained from different sources. Apart from a time-consumption of the sieve analysis methods their basic metrological and technique inconvenience is the limitation to grain classes, which number is determined by the number and mesh clearance of sieves applied in the set. However, in investigations of surface phenomena occurring in processes of preparation of multi-component moulding sands with binders moisturising the quartz matrix, in reclamation of spent sands, in washing out assessments, in investigating harmfulness of wastes, the high resolution of grain classes (in the total range of the technologically acceptable granular range) is necessary. The results of comparable analysis of grain sizes of the selected moulding sands performed by means of the normalised classic method and by means of the ANALYSETTE 22 Nano Tec equipment for measuring grain sizes in a solid phase and in suspension, are discussed in the paper. This apparatus, which is the most recent technical novelty, a convergent laser beam is applied for the determination of the grain size distribution in solids, water suspensions, emulsions and aerosols. The repeatability and accuracy of measurements fulfils demands of ISO 13320 standards [9]. Taking as an example the grain size analysis of used moulding sands and dusts from the dry reclamation process, the possibility of their deeper assessment was pointed out in the paper. Such assessment is especially important in designing of dust collection devices, used in several foundry processes, where identification of the total spectrum of grain sizes is essential.

PL

Znajomość rozkładu uziarnienia w materiałach polidyspersyjnych, którymi są między innymi piaski formierskie stosowane w odlewnictwie, ma istotne znaczenie dla właściwej interpretacji wyników badań procesów technologicznych wpływających w konsekwencji na jakosc odlewów. Aktualnie badania uziarnienia piasków formierskich są prowadzone metodami analizy sitowej zgodnie z obowiazującymi w danych krajach normami, które wymagają przetwarzania wyników uzyskiwanych z różnych źródeł. Pomijając pracochłonność metod analizy sitowej, ich podstawowa niedogodnościa metrologiczna i techniczna jest ograniczenie się do klas ziarnowych, których liczba jest determinowania przez ilość i rozmiary sit stosowanych w zestawie przesiewającym. W badaniach zjawisk powierzchniowych, zachodzących w procesach sporządzania wieloskładnikowych mas ze spoiwami zwilżającymi kwarcowa osnowe, regeneracji mas zużytych, ocenie wymywalności, w badaniach szkodliwości odpadów – konieczna jest duża rozdzielczość klas ziarnowych w całym przedziale ziarnistości akceptowalnym przez technologie oraz tych, które tworza odpad. W artykule omówiono wyniki analizy porównawczej ziarnistości wybranych piasków formierskich dokonanej znormalizowana metoda klasyczna oraz za pomocą aparatu ANALYSETTE 22 Nano Tec do pomiaru wielkości cząstek w fazie stałej i zawiesinie. W tym aparacie, który aktualnie stanowi nowość techniczna, wykorzystuje się zbieżny strumień laserowy do określania rozkładu uziarnienia w ciałach stałych, zawiesinie wodnej, emulsji i aerozolach z bardzo dużą powtarzalnością i dokładnością wyników, spełniajacych wymagania normy ISO 13320 [9]. W pracy, na przykładzie analizy uziarnienia masy zużytej formierskiej oraz pyłów z procesu regeneracji suchej, wykazano możliwosci ich pogłebionej oceny, szczególnie ważnej w projektowaniu urządzeń odpylajacych, stosowanych w wielu procesach odlewniczych, gdzie ważna jest identyfikacja pełnego spektrum składu granulometrycznego.

6

Influence of Silica Sand on Surface Casting Quality

63%

Beňo J. , Adamusová K. , Merta V. , Bajer T.

Archives of Foundry Engineering

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2019

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tom iss. 2

5--8

EN

The current casting production of castings brings increased demands for surface and internal quality of the castings. Important factors, that influence the quality of casted components, are the materials used for the manufacture of moulds and cores. For the preparation and production of moulds and cores, in order to achieve a low level of casting defects, then it used a high quality input materials, including various types of sands, modified binders, additives, etc. However, even the most expensive raw materials are not a guarantee to achieve the quality of production. It is always necessary to choose the appropriate combination of input material together with an appropriate proposal for the way of the production, the metallurgical treatment of cast alloy, etc. The aim of this paper is to establish the basic principles for the selection of the base core mixtures components – sands to eliminate defects from the tension, specifically veining. Various silica sand, which are commonly used in foundries of Middle Europe region, were selected and tested.

7

Effect of Technological Parameters on the Quality and Dimensional Accuracy of Castings Manufactured by Patternless Process Technology

63%

Krivoš E. , Pastirčák R. , Madaj R.

Archives of Metallurgy and Materials

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2014

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tom Vol. 59, iss. 3

1069--1072

EN

Submitted article deals with the effect of selected technological parameters on the quality and dimensional accuracy of prototype castings made by Patternless process technology. During experiments were used two types of molding compounds (foamed gypsum and compound based on silica sand and resin). Experiments were focused on optimization of cutting parameters in terms of efficiency, accuracy and possibilities to minimize tool wear. Article deals also with the dimensional and shape accuracy of the castings made by Z-Cast technology. The main aim of the research is to optimize Patternless process technology to such an extent, that achieved dimensional and shape accuracy will be comparable to castings made by the Z-Cast technology.

PL

Artykuł dotyczy wybranych parametrów technologicznych, które wpływają na jakość i dokładność wymiarową odlewów prototypowych wykonanych technologią bezmodelową. Podczas eksperymentów wykorzystano dwa rodzaje form (spienionego gipsu i mas do formowania na bazie piasku kwarcowego i żywicy). Badania maja na celu optymalizacje parametrów cięcia w zakresie wydajności, dokładności i zminimalizowania zużycia narzędzi. Artykuł zajmuje sie również dokładnością wymiarów i kształtem odlewów wytwarzanych za pomocaąZ-cast. Głównym celem tego badania jest bezmodelowa technika optymalizacji tworzenia do takiego stopnia, aby osiągnąć dokładność wymiarów i kształtu odlewu wytworzonego z pomocą Z-cast.

8

Badania mas formierskich i rdzeniowych przeznaczonych do produkcji odlewów staliwnych z zastosowaniem nowego spoiwa geopolimerowego

63%

Pezarski F. , Maniowski Z. , Izdebska-Szanda I. , Smoluchowska E.

Archiwum Odlewnictwa

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2006

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tom R. 6, nr 20

65--70

PL

W artykule przedstawiono wyniki badań laboratoryjnych właściwości technologicznych mas formierskich samoutwardzalnych z udziałem nowej ekologicznej kompozycji wiążącej - spoiwa geopolimerowego. Przedstawiono porównanie właściwości technologicznych tych mas z właściwościami mas samoutwardzalnych ze szkłem wodnym typu „floster”. Przedstawiono próby wykonywania mas formierskich, form i odlewów staliwnych z zastosowaniem nowej kompozycji wiążącej w warunkach przemysłowych.

EN

The article presents the results of laboratory tests of the technological properties of the self-setting moulding sands prepared with the addition of a new, ecological geopolymer binder composition. The technological properties of these sands were compared with the properties of the self-setting sands made with „floster” sodium silicate binder. The pilot production under industrial conditions of moulding sands, and of moulds and steel castings with the new binding composition was described.

9

Microstructure, SDAS and Mechanical Properties of A356 alloy Castings Made in Sand and Granulated Blast Furnace Slag Moulds

51%

Jinugu B. R. , Inampudi N. M.

Archives of Foundry Engineering

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2017

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tom Vol. 17, iss. 1

179--191

EN

Investigations were carried out to ensure the granulated blast furnace (GBF) slag as an alternative mould material in foundry industry by assessing the cast products structure property correlations. Sodium silicate-CO2 process was adopted for preparing the moulds. Three types of moulds were made with slag, silica sand individually and combination of these two with 10% sodium silicate and 20 seconds CO2 gassing time. A356 alloy castings were performed on these newly developed slag moulds. The cast products were investigated for its metallography and mechanical properties. Results reveal that cast products with good surface finish and without any defects were produced. Faster heat transfers in slag moulds enabled the cast products with fine and refined grain structured; and also lower Secondary Dendrite Arm Spacing (SDAS) values were observed than sand mould. Slag mould casting shows improved mechanical properties like hardness, compression, tensile and impact strength compared to sand mould castings. Two types of tensile fracture modes, namely cleavage pattern with flat surfaces representing Al−Si eutectic zone and the areas of broken Fe-rich intermetallic compounds which appear as flower-like morphology was observed in sand mould castings. In contrast, GBF slag mould castings exhibit majority in dimple fracture morphology with traces of cleavage fracture. Charpy impact fractured surfaces of sand mould castings shows both transgranular and intergranular fracture modes. Only intergranular fracture mode was noticed in both GBF slag and mixed mould castings.