March 2008
Microcellular Al2O3-Ceramics
859
10C. E. Byrne and D. E. Nagle, ‘‘Cellulose Derived Composites—A New Meth-
od for Materials Processing,’’ Mater. Res. Innovat., 1 [1] 137–44 (1997).
11P. Greil, ‘‘Biomorphous Ceramics from Lignocellulosics,’’ J. Eur. Ceram. Soc.,
21, 105–18 (2001).
properties of the honeycomb-like structure characterized by the
methaxylem vessels with the brittle crushing of the 3D cellular
structure related to the phloem cells. A value of n 5 3.1 was
found for biomorphous Al2O3 derived from rattan under axial
loading (solid curve). C1 was found to be 0.05 (coefficient of
correlation, r 5 0.89) for the GA and 0.57 for n 5 3.1 (coefficient
of correlation, r 5 0.97). The value of n depends on the micro-
mechanical model used to describe the material as well as the
mechanism of load transfer among the constituents of the po-
rous material.41 Additionally, lower sS values can be related to
high degrees of pore disorder, yielding higher values of n.
12P. Greil, T. Lifka, and A. Kaindl, ‘‘Biomorphic Cellular Silicon Carbide
Ceramics from Wood: I. Processing and Microstructure,’’ J. Eur. Ceram. Soc., 18
[14] 1961–73 (1998).
13E. Vogli, J. Mukerji, C. Hoffmann, R. Kladny, H. Sieber, and P. Greil, ‘‘Con-
version of Oak to Cellular Silicon Carbide Ceramic by Gas-Phase Reaction with
Silicon Monoxide,’’ J. Am. Ceram. Soc., 84 [6] 1236–40 (2001).
14H. Sieber, E. Vogli, F. Muller, P. Greil, N. Popovska, H. Gerhard, and
¨
G. Emig, ‘‘Gas Phase Processing of Porous, Biomorphic SiC Ceramics,’’ Key Eng.
Mater., 206–213, 2013–6 (2002).
15E. Vogli, H. Sieber, and P. Greil, ‘‘Biomorphic SiC-Ceramic Prepared by
Si-Gas Phase Infiltration of Wood,’’ J. Eur. Ceram. Soc., 22 [14–15] 2663–8
(2002).
16C. R. Rambo, J. Cao, O. Rusina, and H. Sieber, ‘‘Manufacturing of Biom-
orphic (Si, Ti, Zr)-Carbide Ceramics by Sol–Gel Processing,’’ Carbon, 43 [6] 1174–
83 (2005).
IV. Conclusions
In summary, Al2O3 ceramics with uniaxial-directed porosity
in the micrometer range were produced from rattan via an Al
vapor phase infiltration reaction to carbon biotemplates and
subsequent oxidation of Al4C3. The biomorphous Al2O3 ceram-
ics retained the anatomical features of the original native bi-
ostructure down to the micrometer level. The air pressure drop
through the biomorphous Al2O3 ceramics within the tested su-
perficial air velocity range is described by a parabolic behavior
(Forchheimer’s equation), which is characterized by a Darcian
permeability constant (k1), and a non-Darcian permeability
constant (k2), related to viscous and inertial fluid regimes, re-
spectively. The Darcian permeability of the biomorphous Al2O3
ceramics was found to be in the range of 1–8 ꢀ 10ꢁ9 m2, which is
in the order of magnitude of gas filter supports, and, therefore,
also suitable for several technological applications. Owing to the
high anisotropy of biomorphous Al2O3, the compressive
strength behavior was strongly dependent on the loading direc-
tion, especially in rattan-derived samples. During processing, the
microstructure of rattan and pine was converted into alumina
and yielded a porous material with a novel, directed pore
morphology that cannot be prepared by conventional ceramic
processing technologies and may be interesting for micro-
structural-designed filter and micro reactor devices.
17T. Ota, M. Takahashi, T. Hibi, M. Ozawa, S. Suzuki, and Y. Hikichi, ‘‘Bio-
mimetic Process for Producing SiC Wood,’’ J. Am. Ceram. Soc., 78 [12] 3409–11
(1995).
18C. Zollfrank, R. Kladny, G. Motz, H. Sieber, and P. Greil, ‘‘Manufacturing of
Anisotropic Ceramics from Preceramic Polymer Infiltrated Wood,’’ Ceram.
Trans., 129, 43–50 (2002).
19C. R. Rambo and J. M. Martinelli, ‘‘Synthesis and Characterization of SiC
from Bamboo,’’ Key Eng. Mater., 189, 9–15 (2001).
20M. Patel and B. K. Padhi, ‘‘Production of Alumina Fibre Through Jute Fibre
Substrate,’’ J. Mater. Sci., 25, 1335–43 (1990).
21M. Patel and B. K. Padhi, ‘‘Titania Fibres Through Jute Substrates,’’
J. Mater. Sci. Lett., 12, 1234–5 (1993).
22T. Ota, M. Imaeda, H. Takase, M. Kobayashi, N. Kinoshita, T. Hirashita,
H. Miyazaki, and Y. Hikichi, ‘‘Porous Titania Ceramic Prepared by Mimicking
Silicified Wood,’’ J. Am. Ceram. Soc., 83 [6] 1521–3 (2000).
23H. Sieber, C. Rambo, J. Cao, E. Vogli, and P. Greil, ‘‘Manufacturing of Po-
rous Oxide Ceramics by Replication of Wood Morphologies,’’ Key Eng. Mater.,
206–213, 2009–12 (2002).
24J. Cao, C. R. Rambo, and H. Sieber, ‘‘Manufacturing of Microcellular,
Biomorphous Oxide Ceramics from Native Pine Wood,’’ Ceram. Int., 30 [7]
1967–70 (2004).
25T. M. Ul’yanova and L. T. Sivakova, ‘‘Production of High-Melting Ceramic
Fibers from Vegetable Raw Materials,’’ Russ. J. Appl. Chem., 71, 1450–4
(1998).
26C. R. Rambo, J. Cao, and H. Sieber, ‘‘Preparation and Properties of Highly
Porous, Biomorphic YSZ Ceramics,’’ Mater. Chem. Phys., 87 [2–3] 345–52
(2004).
27J. Cao, C. R. Rambo, and H. Sieber, ‘‘Preparation of Porous Al2O3-Ceramics
by Biotemplating of Wood,’’ J. Porous Mater., 11, 163–72 (2004).
28H. R. Maier, ‘‘Porous Ceramics Functional Cavities for System Innovation’’;
pp. 537–42 in Ceramic Materials and Components for Engines, Edited by J. G.
Heinrich and F. Aldinger. Wiley-VCH, Portland, OR, 2001.
29A. R. Studart, U. T. Gonzenbach, E. Tervoort, and L. J. Gauckler, ‘‘Pro-
cessing Routes to Macroporous Ceramics—A Review,’’ J. Am. Ceram. Soc., 89 [6]
1771–89 (2006).
Acknowledgments
C. R. Rambo thanks CNPq-Brazil for the scholarship. The authors thank the
Volkswagen Foundation for the financial support under contract I/73043.
30L. J. Gibson and M. F. Ashby, Cellular Solids: Structure and Properties. Per-
gamon Press, New York, 1988.
References
31C. R. Rambo, ‘‘Synthesis and Characterization of Biomorphic Ceramics,’’
1N. L. Freitas, J. A. S. Gon@alves, M. D. M. Innocentini, and J. R. Coury,
‘‘Development of a Double-Layered Ceramic Filter for Aerosol Filtration at High-
Temperatures: The Filter Collection Efficiency,’’ J. Hazard. Mater., 136 [3] 747–56
(2006).
˜
Ph.D. Thesis, Sao Paulo, Brazil, 2001.
32C. Couroyer, Z. Ning, M. Ghadiri, N. Brunard, F. Kolenda, D. Bortzmeyer,
and P. Laval, ‘‘Breakage of Macroporous Alumina Beads under Compressive
Loading: Simulation and Experimental Validation,’’ Powder Technol., 105, 57–65
(1999).
2P. Pastila, V. Helanti, A. P. Nikkila
¨ ¨
, and T. Mantyl, ‘‘Environmental Effects on
33N. W. Uhl and J. Dransfield, General Palmarum, A Classification of Palms
Based on the Work of H. E. Moore Jr. Bailei. Hortorium and International Palm
Society, Kansas, 1987.
Microstructure and Strength of SiC-Based Hot Gas Filters,’’ J. Eur. Ceram. Soc.,
21 [9] 1261–8 (2001).
3V. R. Salvini, A. M. Pupim, M. D. M. Innocentini, and V. C. Pandolfelli,
‘‘Processing Optimization for Production of Al2O3–SiC Ceramic Filters,’’ Ceraˆmi-
ca, 47 [301] 13–8 (2001).
34C. R. Rambo and H. Sieber, ‘‘Novel Synthetic Route to Biomorphic Al2O3
Ceramics,’’ Adv. Mater., 17 [8] 1088–91 (2005).
4V. R. Salvini, M. D. M. Innocentini, and V. C. Pandolfelli, ‘‘Influence of
Ceramic Processing on the Mechanical Resistance and Permeability of Filters in
the Al2O3–SiC System,’’ Ceraˆmica, 48 [308] 122–5 (2002).
35R. Brezny and D. Green, ‘‘Uniaxial Strength Behavior of Brittle Cellular
Materials,’’ J. Am. Ceram. Soc., 76 [9] 2185–92 (1993).
36C. Q. Dam, R. Brezny, and D. J. Green, ‘‘Compressive Behavior and Defor-
mation-Mode Map of an Open Cell Alumina,’’ J. Mater. Res., 5 [1] 163–71
(1990).
5V. R. Salvini, M. D. M. Innocentini, and V. C. Pandolfelli, ‘‘Relationship
Between Permeability and Mechanical Strength of Al2O3–SiC Ceramic Filters,’’
Ceraˆmica, 46 [298] 97–103 (2000).
37P. Greil, T. Lifka, and A. Kaindl, ‘‘Biomorphic Cellular Silicon Carbide
Ceramics from Wood: II. Mechanical Properties,’’ J. Eur. Ceram. Soc., 18 [14]
1975–83 (1998).
6M. D. M. Innocentini, P. Sepulveda, V. R. Salvini, and V. C. Pandolfelli,
‘‘Permeability and Structure of Cellular Ceramics: A Comparison Between Two
Preparation Techniques,’’ J. Am. Ceram. Soc., 81 [12] 3349–52 (1998).
7E. A. Moreira and J. R. Coury, ‘‘The influence of Structural Parameters on the
Permeability of Ceramic Foams,’’ Braz. J. Chem. Eng., 21 [1] 23–33 (2004).
8M. D. M. Innocentini, V. R. Salvini, V. C. Pandolfelli, and J. R. Coury,
‘‘Assessment of Forchheimer’s Equation to Predict the Permeability of Ceramic
Foams,’’ J. Am. Ceram. Soc., 82 [7] 1945–8 (1999).
38P. Greil, E. Vogli, T. Fey, A. Bezold, N. Popovska, H. Gerhard, and H. Sieber,
‘‘Effect of Microstructure on the Fracture Behavior of Biomorphous Silicon
Carbide Ceramics,’’ J. Eur. Ceram. Soc., 22 [14–15] 2697–707 (2002).
39A. S. Wagh, R. B. Poeppel, and J. P. Singh, ‘‘Open Pore Description of
Mechanical Properties of Ceramics,’’ J. Mater. Sci., 26 [14] 3862–8 (1991).
40L. J. Gibson, ‘‘Biomechanics of Cellular Solids,’’ J. Biomech., 38 [3] 377–99
(2005).
9A. H. Heuer, D. J. Fink, V. J. Arias, P. D. Calvert, K. Kendali, G. L. Messing,
J. Blackwell, P. C. Rieke, D. H. Thompson, A. P. Wheeler, A. Veis, and A. I.
Caplan, ‘‘Innovative Materials Processing Strategies: A Biomimetic Approach,’’
Science, 255 [5048] 1098–105 (1992).
41F. A. C. Oliveira, S. Dias, M. F. Vaz, and J. C. Fernandes, ‘‘Behaviour of
Open-Cell Cordierite Foams under Compression,’’ J. Eur. Ceram. Soc., 26 [1–2]
179–86 (2006).
&