Mechanical Properties of Gel-Derived Materials
Rent the article at a discountRent now
* Final gross prices may vary according to local VAT.Get Access
The mechanical behaviour of xerogels and aerogels is generally described in terms of brittle and elastic materials, like glasses or ceramics. The main difference compared to silica glass is the order of magnitude of the elastic and rupture moduli which are 104 times lower. However, if this analogy is pertinent when gels are under a tension stress (bending test) they exhibit a more complicated response when the structure is submitted to a compressive stress. The network is linearly elastic under small strains, then exhibits yield followed by densification and plastic hardening. As a consequence of the plastic shrinkage it is possible to densify and stiffen the gel at room temperature. These opposite behaviours (elastic and plastic) are surprisingly related to the same two kinds of gel features: the silanol content and the pore volume. Both elastic modulus and plastic shrinkage depend strongly on the volume fraction of pores and on the condensation reaction between silanols. On the mechanical point of view (rupture modulus and toughness), it is shown that pores and silanols play also an important role. Pores can be considered as flaws in the terms of fracture mechanics and the flaw size, calculated from rupture strength and toughness is related to the pore size distribution. Different kinds of gels structure (fractal or not fractal) have been synthesized by a control of the different steps of transformation such as sintering and plastic compaction. The relationships between structural and the elastic properties are discussed in terms of the percolation theory and fractal structure.
- T. Calemczuk, A.M. de Goer, B. Salce, R. Maynard, and A. Zarembovitch, Europhys. Lett. 3, 1205 (1987).
- J. Gross, G. Reichenauer, and J. Fricke, J. Phys. D21, 1447 (1988).
- J.D. Lemay, T.M. Tillotson, H.W. Hrubesch, and R.W. Pekala, Mater. Res. Soc. Symp. Proc. 180, 321 (1990).
- T. Woignier and J. Phalippou, J. Non-Cryst. Solids 100, 404 (1988).
- G.W. Scherer, J. Non-Cryst. Solids 144, 210 (1992).
- R. Pirard, S. Blacher, F. Brouers, and J.P. Pirard, J. Mater. Res. 10, 1 (1995).
- L. Duffours, T. Woignier, and J. Phalippou, J. Non-Cryst. Solids 194, 283 (1996).
- G.W. Scherer, D.M. Smith, X. Qiu, and J. Anderson, J. Non-Cryst. Solids 186, 316 (1995).
- T. Woignier, J. Phalippou, and M. Prassas, J. Mater. Sci. 25, 3118 (1990).
- P. Etienne, J. Phalippou, T. Woignier, and A. Alaoui, J. Non-Cryst. Solids 188, 19 (1995).
- J.L. Chermant, F. Osterstock, and G. Vadam, Verres Refract. 33(6), 843 (1979).
- C. Janssen, Ceram. Soc. Japan 10, 23 (1974). Proc. 10th Int. Cong. on Glass (Kyoto), 1974.
- C.E. Inglis, Inst. National Architects Trans. 55 (1913).
- A.A. Griffith, Phil. Trans. Roy. Soc. Lon. 221A, 163 (1920).
- G.E. Irwin, Trans. ASM 40A, 47 (1948).
- I. Beurroies, Ph.D. thesis, Montpellier, 1995.
- A. Alaoui, T. Woignier, F. Pernot, and J. Phalippou, J. Non-Cryst. Solids 265, 29 (2000).
- T. Woignier, J. Phalippou, J.F. Quinson, M. Pauthe, and G.W. Scherer, J. Sol-gel Sci. and Tech. 2, 277 (1994).
- M. Wiederhorn, J. Amer. Ceram. Soc. 55, 81 (1972).
- T.A. Mischalske, W.L. Smith, and B.C. Bunker, J. Amer. Ceram. Soc. 74, 1993 (1991).
- B. Gauthier-Manuel and E. Guyon, J. Phys. Lett. France 41, L–503 (1980).
- M. Tokita, R. Niki, and J. Nikichi, J. Chem. Phys. 83, 2583 (1985).
- M. Adam, M. Delsanti, D. Durand, G. Hild, and J.P. Munch, Pure Appl. Chem. 53, 1489 (1981).
- Y. Kantor and I. Webman, Phys. Rev. Lett. 52, 1891 (1984).
- B.I. Halperin, S. Feng, and P.N. Sen, Rev. Phys. Lett. 54, 2391 (1985).
- J.W. Essam, Rep. Prog. Phys. 43, 904 (1980).
- A. Emmerling and J. Friche, J. Sol-gel Sci. and Tech. 8, 781 (1997).
- T. Woignier, J. Reynes, A. Alaoui, J. Beurroies, and J. Phalippau, J. Non-Cryst. Solids 241, 45 (1998).
- Mechanical Properties of Gel-Derived Materials
Journal of Sol-Gel Science and Technology
Volume 19, Issue 1-3 , pp 163-169
- Cover Date
- Print ISSN
- Online ISSN
- Kluwer Academic Publishers
- Additional Links
- mechanical properties
- elastic properties
- Industry Sectors