Long-term Effects of Relative Humidity on Properties of Microwave Hardened Moulding Sand with Sodium Silicate

• Autorzy: Stachowicz M. , Granat K.

Identyfikatory

DOI

10.1515/afe-2017-0104

• Języki publikacji: EN

Abstrakty

EN

Moulding sands containing sodium silicate (water-glass) belong to the group of porous mixture with low resistance to increased humidity. Thanks to hydrophilic properties of hardened or even overheated binder, possible is application of effective methods of hydrous reclamation consisting in its secondary hydration. For the same reason (hydrophilia of the binder), moulds and foundry cores made of high-silica moulding sands with sodium silicate are susceptible to the action of components of atmospheric air, including the contained steam. This paper presents results of a research on the effect of (relative) humidity on mechanical and technological properties of microwave-hardened moulding mixtures. Specimens of the moulding sand containing 1.5 wt% of sodium water-glass with module 2.5 were subjected, in a laboratory climatic chamber, to long-term action of steam contained in the chamber atmosphere. Concentration of water in atmospheric air was stabilized for 28 days (672 h) according to the relative humidity parameter that was ca. 40%, 60% and 80% at constant temperature 20 °C. In three cycles of the examinations, the specimens were taken out from the chamber every 7 days (168 h) and their mechanical and technological parameters were determined. It was found on the grounds of laboratory measurements that moulds and cores hardened with microwaves are susceptible to action of atmospheric air and presence of water (as steam) intensifies action of the air components on glassy film of sodium silicate. Microwave-hardened moulding sands containing sodium silicate may be stored on a long-term basis in strictly determined atmospheric conditions only, at reduced humidity. In spite of a negative effect of steam contained in the air, the examined moulding mixtures maintain a part of their mechanical and technological properties, so the moulds and foundry cores stored in specified, controlled conditions could be still used in manufacture.

Słowa kluczowe

EN

foundry; sodium silicate; humidity; microwaves; high-silica sand

PL

odlewnia; krzemian sodu; wilgotność; mikrofale; piasek kwarcowy

• Wydawca: Komisja Odlewnictwa Polskiej Akademii Nauk Oddział w Katowicach
• Czasopismo: Archives of Foundry Engineering
• Rocznik: 2017
• Tom: Vol. 17, iss. 3
• Strony: 127--132
• Opis fizyczny: Bibliogr. 21 poz., il., tab., wykr.

Twórcy

autor

Stachowicz M.

• Department of Foundry Engineering, Plastics and Automation, Wroclaw University of Technology, ul. Smoluchowskiego 25, 50-372 Wrocław, Poland

autor

Granat K.

• Department of Foundry Engineering, Plastics and Automation, Wroclaw University of Technology, ul. Smoluchowskiego 25, 50-372 Wrocław, Poland

Bibliografia

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Uwagi

PL

Opracowanie ze środków MNiSW w ramach umowy 812/P-DUN/2016 na działalność upowszechniającą naukę (zadania 2017)