Porous Alumina Ceramics with Unidirectional Oriented Pores Fabricated by Ionotropic Process of Sodium Alginate

doi:10.15541/jim20150049

Abstract

Abstract:

Alumina ceramic bodies with high porosity characterized by highly ordered and unidirectional oriented pores were successfully fabricated using the ionotropic process of sodium alginate by solvent exchange subsequently with freeze-drying. It is important to point out that the whole process and raw materials are eco-friendly. The average unidirectional pore size of samples sintered at 1500℃ for 2 h is 200 μm with minor porosity in the pore walls with average pore size of 0.3-0.5 μm. The properties of samples can be adjusted by controlling the solid loading in slurry. As the solid loading increasing from 5wt% to 15wt%, the density and compressive strength increased from 0.87 g/cm³ to 1.16 g/cm³ and from (18.9±3.2) MPa to (44.2±5.4) MPa, respectively with permeability decreasing from 2.57×10^-11m² to 2.16×10^-11m². In addition, with the solid loading increasing from 5wt% to 15wt%, the conductivity of the direction parallel and perpendicular to the unidirectional pores increased from 2.1 W/(m·K) to 3.1 W/(m·K) and from 1.3 W/(m·K) to 1.7 W/(m·K), respectively.

Key words: unidirectionally oriented porous alumina ceramics, permeability, thermal conductivity, ionotropic

CLC Number:

TQ174

SUN Yang, XUE Wei-Jiang, SUN Jia-Lin, ZHOU Guo-Zhi, HUANG Yong. Porous Alumina Ceramics with Unidirectional Oriented Pores Fabricated by Ionotropic Process of Sodium Alginate[J]. Journal of Inorganic Materials, 2015, 30(8): 877-881.

Figures/Tables 9

Fig. 1 Schematic illustrations for fabricating alumina ceramics by sodium alginate ionotropic

Fig. 2 Formation of unidirectional porous structures in samples[17]

Fig. 3 Microstructures of surface (a) and cross-section (b) of NaAlg/Al2O3 gels

Fig. 4 Effects of drying methods on microstructures (a) Freeze-drying; (b) Evaporating in air

Fig. 5 SEM images of microstructures with different solid loadings (a) 5wt%; (b) 10wt%; (c) 15wt%

Fig. 6 Microstructures of the pore walls of alumina porous ceramics

Fig. 7 Pore size distribution of samples with different solid loadings

Table 1 Density, open porosity, permeability and compressive strength of samples with different solid loadings

Solid loading /wt%	Open porosity /%	Density/ (g·cm^-3)	Compressive strength /MPa	Permeability /(×10^-11, m²)
5	70.5	0.87	18.9±3.2	2.57
10	66.1	0.99	32.8±4.1	2.42
15	63.5	1.16	44.2±5.4	2.16

Table 2 Thermal conductivity of samples with different solid loadings

Solid loading /wt%	Thermal conductivity_∥/(W·m^-1·K^-1)	Thermal conductivity_⊥/(W·m^-1·K^-1)
5	2.08	1.36
10	2.18	1.57
15	3.03	1.78

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