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1
Content available 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.
2
Content available The Measurement of High-Temperature Expansion as the Standard of Estimation the Knock-Out Properties of Moulding Sands with Hydrated Sodium Silicate
Major-Gabryś K., Dobosz S.M., Jelínek P., Jakubski J., Beňo J.
Archives of Metallurgy and Materials
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2014
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Vol. 59, iss. 2
739--742
EN
The necessity of receiving high quality castings forces undertaking research to elaborate moulding and core sands ensuring obtaining the materials with relevant technological parameters and also with high environmental standards. The most important group here are moulding sands with hydrated sodium silicate. Unfortunately, their fundamental disadvantages are weak knock-out properties. The article presents the most commonly used methods of measuring the knock-out properties of moulding and core sands. The authors propose a new method for estimation this parameter. The method is based on the measurement of high-temperature expansion.
PL
Potrzeba uzyskiwania wysokiej jakości odlewów wymusza podejmowanie prac badawczych dla otrzymania mas formierskich i rdzeniowych zapewniających uzyskanie tworzyw o odpowiednich parametrach technologicznych, jednocześnie spełniających wysokie wymogi ochrony środowiska. Najważniejszą grupę stanowią tutaj masy z uwodnionym krzemianem sodu. Niestety jedną z ich podstawowych wad jest słaba wybijalność. W artykule zostały przedstawione najczęściej stosowane metody pomiaru wybijalności mas formierskich i rdzeniowych Autorzy zaproponowali nową metodę oceny wybijalności opierającą się na pomiarze ekspansji wysokotemperaturowej.
3
Content available Nowoczesne spoiwo ekologicznych mas formierskich zawierające modyfikowany krzemian sodu
Major-Gabryś K., Dobosz S. M., Jakubski J.
Archives of Foundry Engineering
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2013
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Vol. 13, iss. 1 spec.
111--116
PL
Niniejszy artykuł dotyczy ekologicznych mas z uwodnionym krzemianem sodu jako spoiwem. Nieorganiczny charakter spoiwa – zapewniający niską szkodliwość dla środowiska - powoduje jednak złą wybijalność oraz małą zdolność do regeneracji mechanicznej mas. W niniejszym artykule autorzy skupili się na opracowaniu nowego składu tych przyjaznych dla środowiska mas formierskich- zapewniając ich lepszą wybijalność. W wyniku analizy danych literaturowych i badań własnych zastosowano do mas z uwodnionym krzemianem sodu nowe dodatki zawierające Al2O3. Dodatki te zapewniają lepszą wybijalność masy określaną na podstawie pomiaru wytrzymałości końcowej na ściskanie Rctk, a także pomiaru ekspansji cieplnej mas. Autorzy opracowali nowy dodatek zawierający Al2O3 i wykazali jego pozytywny wpływ na wybijalność mas z uwodnionym krzemianem sodu.
EN
The article is devoted to ecological foundry moulding sands with hydrated sodium silicate as a binder. Unfortunately the inorganic nature of the binder results in moulding sand’s poor knock-out properties and low ability to mechanical reclamation. In the present study authors focused on developing a new addition to these environmental friendly foundry moulding sands, given them better knock-out properties. The analysis of the literature data and own researches let authors usage of additives containing Al2O3 as components of moulding sands with hydrated sodium silicate. These additives provide better knock-out properties of moulding sands measured according to retained strength Rctk and also lead to lower thermal expansion of moulding sands. The authors have developed a new additive containing Al2O3 and proved its positive impact on moulding sand with hydrated sodium silicate knock-out properties.
4
Content available remote Influence of water-glass grade and quantity on residual strength of microwave-hardened moulding sands. Part 2
Stachowicz M., Granat K., Nowak D.
Archives of Foundry Engineering
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2011
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Vol. 11, iss. 2
143-148
EN
The paper continues dealing with the issues of influence of microwave hardening on mechanical properties of waterglass-based moulding sands. This second part of the research includes examining moulding sands containing 1.5, 2.5 and 3.5% of hydrated sodium silicate grade 150. Standardised, microwave-hardened cylindrical specimens for mechanical testing were held at temperatures from 100 to 1200 oC for 30 minutes, cooled-down to ambient temperature and then their residual strength was determined. An attempt was made to explain the effect of microwave hardening on strength of moulding sands as a function of baking temperature, supported by SEM observations of the baked sandmixes. On the grounds of these observations, destruction nature of linking bridges was identified. It was found that the applied microwave hardening is beneficial by reducing residual strength of waterglass-containing moulding sands and thus improving their knockout properties.
5
Content available remote Influence of water-glass grade and quantity on residual strength of microwave-hardened moulding sands. Part 1
Stachowicz M., Granat K., Nowak D.
Archives of Foundry Engineering
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2011
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Vol. 11, iss. 1
93-98
EN
The paper presents a research on influence of dielectric drying process on mechanical properties of water-glass containing moulding sands. Examined were moulding sands containing additions of 1.5 and 2.5 % of hydrated sodium silicate grades 145, 149 and 150, most often used in foundry practice. Standard, cylindrical specimens for mechanical testing were held at temperatures from 100 to 1200 oC for 30 minutes and next cooled-down to ambient temperature. Then their residual strength was determined. Comparison of the obtained results with literature data indicates that dielectric drying is favourable for reduction of residual strength of used water-glass moulding sands, and thus improves their knock-out properties.
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