Abstract
Mg-bearing silicate precursor gels have been prepared by mixing 0.74 mol/L sodium metasilicate and 1.48 mol/L magnesium nitrate solutions. Caustic soda solution of 1.0 mol/L concentration was introduced to regulate pH. The magnesium nitrate solution was added dropwise to the sodium silicate solution in equi-volume at various pH values. Raw and heat-treated gels were characterized by XRF, TG-DTA, XRD and FE-SEM. As a result, gel compositions were dependent on pH values of mixing solutions. The pH value yielding stoichiometric forsterite composition, MgO/SiO2 = 2 was reached at pH 9.3. In addition, this value was pH 8.4 for stoichiometric enstatite composition, MgO/SiO2 = 1. With decreasing pH from 9.3, the ratio became less than 2 and forsterite and enstatite precipitated by heating the gels. With increasing pH from 9.3, the ratio became more than 2 and forsterite and periclase precipitated by heating the gels. DTA curves showed a characteristic exothermic peak centered at 700–900∘C, indicating relatively low temperature formation of crystalline phases due to the presence of polycondensed frame works of silicates in the precursor gels.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
G.W. Brindley and R. Hayami, Philos. Mag. 12, 505 (1965).
M.T. Tsai, J. Eur. Ceram. Soc., 23, 1283 (2003).
T. Ban, Y. Ohya, and Y. Takahashi, J. Am. Ceram. Soc. 82(1), 22 (1999).
D.G. Park, M.H.E. Martin, C.K. Ober, and J.M. Burlitch, J. Am. Ceram. Soc. 77(1), 33 (1994).
M.B.D. Mitchell, D. Jackson, and P.F. James, J. Sol-Gel Sci. Tech. 15, 211 (1999).
M.B.D. Mitchell, D. Jackson, and P.F. James, J. Sol-Gel Sci. Tech. 13, 359 (1998).
T. Iwahiro, Y. Nakamura, R. Komatsu, and K. Ikeda, J. Eur. Cerm. Soc. 21, 2515 (2001).
T. Iwahiro, R. Komatsu, and K. Ikeda, in Proc. Geopolymers 2002, edited by G. C. Luckey (Published by Organizing Committee of Geopolymers, Melbourne, 2002), p. 175.
K. Ikeda, K. Onikura, Y. Nakamura, and S. Vedanand, J. Am. Ceram. Soc. 84(8), 1717 (2001).
R. Vallepu, A. Mikuni, R. Komatsu, and K. Ikeda, J. Mineral. Petrol. Sci. (in press).
J. Davidovits, U.S.Pat. No.4349386, Sept.14 (1982).
A. Palomo, M. T. Macias, M.T. Blanco, and F. Puertas, in Proc. 9th Int. Cong. Chem. Cement, edited by National Council for the Cement and Building Materials (Published by Tara Art Press, New Delhi,1992), Vol. 5 p. 371.
K. Ikeda, Cem. Conc. Res. 27, 657 (1997).
K. Ikeda, T. Nunohiro, and N. Iizuka, Chem. Pap. 52, 214 (1998).
K. Ikeda and Y. Nakamura, in Proc.PacRim2, Cairns, Symp., edited by P. Walls, C. Sorrell, and A. Ruys (Published by Australian Ceramic Society, Menai, NSW, 1996), Vol. 18, p. 227.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Vallepu, R., Nakamura, Y., Komatsu, R. et al. Preparation of Forsterite by the Geopolymer Technique—Gel Compositions as a Function of pH and Crystalline Phases. J Sol-Gel Sci Technol 35, 107–114 (2005). https://doi.org/10.1007/s10971-005-1375-4
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s10971-005-1375-4