Technical silicification of wood materials
- 1 — Freiberg University of Mining and Technology
- 2 — Freiberg University of Mining and Technology
- 3 — Freiberg University of Mining and Technology
- 4 — Freiberg University of Mining and Technology
Abstract
Technical silicification of wood was performed to improve the properties (e.g. wear resistance, water absorption, hardness) of the material. Experimental studies were carried out using two types of wood (oak and spruce) and three different sources of silica including sodium metasilicate (Na 2 SiO 3 ), a colloidal suspension of silica (CSS), and tetraethoxysilane (TEOS). Experiments were done in the temperature range between 40 °С and 80 °C under normal pressure in glass beakers and at higher temperatures (up to 138 °C) and pressures (up to 12 bar) in autoclaves. Besides microscopic investigations (binocular, polarizing microscopy, SEM, cathodoluminescence microscopy), measurements of water absorption and hardness were performed. CL microscopy proved to be the most effective method to reveal the distribution of SiO 2 within and on the surface of the wood samples. Material silicified with colloidal silica and TEOS, respectively absorbed about 40 % less water than untreated specimens. Likewise, the Brinell hardness of treated samples could be increased by nearly 100 % compared to fresh wood samples, which is mainly caused by vitreous silica coatings (generated by sol-gel transformation) at the sample surface.
References
- Drum, R.W. 1968a. Silicification of Betula woody tissue in vitro. Science 161: 175 – 176.
- Drum, R.W. 1968b. Petrification of plant tissue in the laboratory. Nature 218: 784 – 785.
- Leo, R.F. & Barghoorn, E.S. 1976. Silicification of wood. Harvard Bot. Mus. Leafl., Harvard Univ. 25: 1 – 47.
- McCafferty, P. 1992. Instant petrified wood. Popular Science 241 (4): 56 – 57.
- Nennewitz, I., Nutsch, W. & Peschel, P. 1999. Holztechnik, Tabellenbuch. Haan-Gruiten: Nourney, Vollmer GmbH & Co., Verlag Europa-Lehrmittel. 327p.
- Oehler, J.H. & Schopf, J.W. 1971. Artificial microfossils: experimental studies of permineralisation of blue-green algae in silica. Science 174: 1229 – 1231.
- Saka, S. & Tanno S. 1996. Wood-inorganic composites prepared by the sol-gel process. Part VI. Effects of a property-enhancer on fire-resistance in SiO2-P2O5 and SiO2-B2O3 wood inorganic composites. Mokuzai-Gakkaishi42 (1): 81 – 86.
- Schultze-Lam, S., Ferris, F.G., Konhauser, K.O. & Wiese, R.G. 1995. In situ silicification of an Icelandic hot spring microbial mat: implications for microfossil formation. Can. J. Earth Sci. 32: 2021 – 2026.
- Tanno, F., Saka, S., Yamamoto, A. & Takabe, K. 1998. Antimicrobial TMSAH-Added Wood-Inorganic Composites Prepared by the Sol-Gel Process. Holzforschung 52: 365 – 370.