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Journal of Nanomaterials
Volume 2012 (2012), Article ID 126567, 6 pages
http://dx.doi.org/10.1155/2012/126567
Research Article

Microstructure and Glass Phase of Inorganic Binder Coated on Mold for Thin Casting

1School of Nano and Advanced Materials Engineering, Changwon National University, No. 9 Sarim-dong, Changwon, Gyeongnam 641-773, Republic of Korea
2High Temperature Materials Research Group, Korea Institute of Materials Science, 797 Changwondaero, Changwon, Gyeongnam 641-831, Republic of Korea

Received 11 June 2012; Accepted 4 December 2012

Academic Editor: Zhengren Huang

Copyright © 2012 Eun-Hee Kim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A new dual dipping process has been introduced for the increase in the fracture strength of casting mold through the effective glassification of inorganic binder precursors. Two different dipping processes have been employed to investigate the reactivity of the precursors. Process I is that the substrate was coated with a sodium oxide (Na2O) precursor through dipping in the solution, and then a silicon dioxide (SiO2) precursor was coated onto the substrate coated with the Na2O precursor. Process II is the inverse coating sequence for process I. In the case of the mold prepared by process I, the glass phase converted from the precursors is uniformly observed at the surface of the particle and the interface between particles, compared with that by process II, inducing that the fracture strength of the mold prepared by process I is significantly improved. In addition, when the PDMS without a sol-gel reaction was used as the SiO2 precursor, especially in process II, the glass phase is not absolutely observed at the surface of the particle owing to the evaporation of PDMS and Na ion during the heat treatment, resulting in the collapse of the mold sample after the heat treatment.