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

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Warianty tytułu
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.
Rocznik
Strony
127--132
Opis fizyczny
Bibliogr. 21 poz., il., tab., wykr.
Twórcy
  • Department of Foundry Engineering, Plastics and Automation, Wroclaw University of Technology, ul. Smoluchowskiego 25, 50-372 Wrocław, Poland
autor
  • Department of Foundry Engineering, Plastics and Automation, Wroclaw University of Technology, ul. Smoluchowskiego 25, 50-372 Wrocław, Poland
Bibliografia
  • [1] Akademia Techniczno- Humanistyczna. (06.28.2016). Measurement of relative humidity of air. http://www.zt.ath.bielsko.pl/wilgotnosc_powietrza.pdf (in Polish).
  • [2] Lorenc, H. (2005). Atlas of Polish climate edited by Halina Lorenc. Warszawa: Instytut Meteorologii i Gospodarki Wodnej. (in Polish).
  • [3] Owusu, Y.A., Draper, A.B., Nowicki, R.M. & Cole, G.S. (1980). Humidity resistance of sodium silicate-bonded sands cured with microwave energy. Transactions of the American Foundrymen's Society. 8, 601-608.
  • [4] Wang, H.F., Lu, J.J., Chen, K.F. & Duan, H.L. (2015). Harmless treatment of used foundry sands and dewatered municipal sludge by microwave. Metalurgija. 54 (3), 459-461.
  • [5] Zych, J. (2007). Behaviour of moulding sands with hydrophilic binders in dry air. Archives of Foundry Engineering. 7(4), 189-192.
  • [6] Wang, H.F., Fan, Z.T., Yu, S., Liu, F.C. & Li, X. (2012). Wet reclamation of sodium silicate used sand and biological treatment of its wastewater by Nitzschia palea. China Foundry. 9 (1), 34-38.
  • [7] Dańko, J., Dańko, R. & Łucarz, M. (2007). Processes and equipment for reclamation of matrix of waste molding sands, Kraków: Scientific Publishing House Akapit (in Polish).
  • [8] Stachowicz, M. & Granat, K. (2015). Influence of melt temperature on strength parameters of cyclically activated used-up sandmixes containing water-glass, hardened with microwaves. Archives of Civil and Mechanical Engineering. 15(4), 831-855.
  • [9] Izdebska-Szanda, I. & Balinski, A. (2011). New generation of ecological silicate binders. Procedia Engineering. 10, 887–893.
  • [10] Bobrowski, A., Kmita, A., Starowicz, M., Stypuła, B. & Hutera, B. (2012). Effect of Magnesium Oxide Nanoparticles on Water Glass Structure. Archives of Foundry Engineering. 12(3), 9-12.
  • [11] Kmita, A. & Hutera, B. (2013). Water glass modification and its impact on the mechanical properties of moulding sands. Archives of Foundry Engineering. 13(2), 81-84.
  • [12] Wang, H.F., Fan Z.T., Liu, F.C. & Li, X. (2012). Preliminary study on humidity resistance of sodium silicate sand hardened by microwave heating coated with eutectic lithium salts. Zhuzao/Foundry. 61(4), 382-385.
  • [13] Liu, F.C., Fan, Z.T., Liu, X., Huang, Y. & Jiang, P. (2016). Effect of surface coating strengthening on humidity resistance of sodium silicate bonded sand cured by microwave heating. Materials and Manufacturing Processes. 31, 1639-1642.
  • [14] Huafang, W., Wenbang, G. & Jijun, L. (2014). Improve the humidity resistance of sodium silicate sands by ester-microwave composite hardening. Metalurgija. 53(4), 455-458.
  • [15] Liu, F., Fan, Z., Liu, X., Wang, H. & He, J. (2014). Research on humidity resistance of sodium silicate sand hardened by twice microwave heating process. Materials and Manufacturing Processes. 29(2), 184-187.
  • [16] Stachowicz, M., Granat, K. & Pałyga, Ł. (2016). The effect of wetting agent on the parameters of dry moulding silica sands bonded with sodium water glass. Transactions of the Foundry Research Institute. 56(1), 43-55.
  • [17] Stachowicz, M., Granat, K. & Pałyga, Ł. (2016). Effect of sand wetting on physically hardened moulding sands containing a selected inorganic binder. Part 2. Archives of Foundry Engineering. 16(1), 79-84.
  • [18] Stachowicz, M., Granat, K. & Nowak, D. (2010). Effect of hardening method and structure of linking bridges on strength of water glass moulding sands. Archives of Foundry Engineering. 10(spec. 2), 141-146.
  • [19] Stachowicz M. (2012). Effect of microwave heating and the composition of moulding sands with sodium silicate on properties of the casting molds and cores.. Unpublished doctoral dissertation, Wroclaw University of Technology, Wroclaw, Polan. (in Polish).
  • [20] Lewandowski, J.L. (1997). Materials for moulds. Kraków: Scientific Publishing House Akapit. (in Polish).
  • [21] Atkins, P.W. (2007) Physical chemistry. Warszawa: Wydawnictwo Naukowe PWN. (in Polish).
Uwagi
PL
Opracowanie ze środków MNiSW w ramach umowy 812/P-DUN/2016 na działalność upowszechniającą naukę (zadania 2017)
Typ dokumentu
Bibliografia
Identyfikator YADDA
bwmeta1.element.baztech-ec72fae6-833e-4aae-a7fd-2afaf2f97e41
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