Preparation and Characterization of Porous Ceramics with ultra-high
porosity
Prof. Chang-An Wang, State Key Laboratory of New Ceramics and Fine Processing, Dept. of
Materials Science & Engineering, Tsinghua University, Beijing 100084, China.
Email: wangca@tsinghua.edu.cn
Porous ceramics are usually understood as materials with porosity over 30%. Porous
ceramics are widely used in various forms and compositions for the purpose of filtration,
separation, diffusion, heat isolation, sound absorption, chemical filling, bioceramics,
chemical sensors and catalyst supporters in many fields, including metallurgy, chemical
engineering, environmental protection, energy sources, biology, food, medicine and etc. [1]
Processing methods used for the production of porous ceramics were recently reviewed
by Gauckler et al.[2], including replica, sacrificial template and direct foaming methods, while
many novel methods are being developed. In principle, the contemporary state of ceramic
technology makes it possible to produce porous ceramics from any nonmetal inorganic
materials. Articles with porosity of 20 – 27% can be produced without great difficulties.
However, production of porous ceramics with high and especially superhigh porosity requires
special techniques.
As a wet shaping technique, gelcasting, which is widely used in advanced ceramics
manufacturing, has also been used to fabricate porous ceramics. [3, 4] In this process, a
suspension with two phases including ceramic powders and a natural or synthetic
pore-forming agent is prepared and subsequently processed by gelcasting. The pore forming
agent is then burned out at temperatures between 200C and 600C, leaving pores with the
same shape. Strong green bodies with homogeneous porous structures can be acquired by this
gelcasting method, whereas materials with complex pore structures are difficult to fabricate.
In this project, gelcasting technology is used to fabricate porous ceramics with ultra-high
porosity (from 60 to 90%). Main work includes: 1) preparation of well-dispersed ceramic
suspension with high stability, 2) gelcasting processing for high quality green bodies, 3)
processing of heat-treatment and sintering, and 4) characterization of properties including
porosity, pore size distribution, and mechanical properties.
Research Tasks:
(1) Study the basic knowledge on advanced ceramics, especially on porous ceramics;
(2) Fabricate porous ceramics with ultra-high porosity (from 60 to 90%) by gelcasting
technology;
(3) Character the structure and properties of the prepared porous ceramics; and
(4) Analyze the relationship among processing, structure and properties of the porous
ceramics.
References
1. Guzman I Y, Certain Principles of Formation of Porous Ceramic Structures. Properties
and Applications (A Review), Glass and Ceramics, 60 [9-10] 280-283 (2003)
2. Studart A R, Gonzenbach U T, Tervoort E, and Gauckler L J, Processing Routes to
Macroporous Ceramics: A Review, J. Am. Ceram. Soc., 89 [6] 1771-1789 (2006)
3. Zhang F Z, Kato T, Fuji M, andu Takahashi M, Gelcasting Fabrication of Porous
Ceramics Using a Continuous Process, J. Eur. Ceram. Soc., 26, 667–671 (2006).
4. Ruifeng Chen, Yong Huang, Chang-An Wang and Jianqiang Qi Ceramics with Ultra
Low Density Fabricated by Gelcasting: An Unconventional View, J. Am. Ceram. Soc.,
90 [11] 3424–3429 (2007)