Preparation of Cordierite Materials with Tailored Porosity by Gelcasting with Polysaccharides

Abstract

This paper deals with the rheological characterization of agar and foaming surfactant‐containing suspensions for obtaining stoichiometric cordierite samples with tailored open macroporosity and their characterization through density and microstructural studies. The influence of the processing parameters solid loading (20, 30, and 45 vol%), slip temperature (65°C, 45°C, and 40°C), and agar/surfactant ratio (10.2, 8.0, and 5.6) on the obtained bodies is discussed. Open Porosity (up to 76 vol%) and average cell size were found to be strongly dependent on solids loading.

Microstructural, mechanical and thermal characterization of alumina gel-cast foams manufactured with the use of agarose as gelling agent

“…Agarose and agar belong to polysaccharides which are formed as a result of transitions hydrogels of a double helix. These environmentally friendly polysaccharides had been recognised as excellent gelling agents not only for alumina but for other kinds of cellular ceramic such as hydroxyapatite, calcium phosphate bioceramics [15,16], glass-hydroxyapatite nanocomposites [17], silicon carbide [12], cordierite [18] and BaTiO 3 [19]. In our present study special attention was directed towards microstructure characterization of alumina foams by micro-computer tomography and mechanical characterization of Young's modulus of alumina foam determined by impulse excitation and ultrasonic sound velocity measurements.…”

Rheology of aqueous mullite–starch suspensions

“…Cooling of agaroids has been widely used for obtaining dense bodies, 8 although porous materials can be easily obtained also. 9,10 The ability to form strong gels on heating is the basis of the so-called "starch consolidation process", a new non-contaminating lowcost consolidation technique based on the gelling capability of starch in aqueous media at temperatures between 55 and 85 • C. In this method, starch acts as a consolidator/binder agent of the ceramic particles as well as a pore former after consolidation by burnout at high-temperature. [11][12][13][14][15] This technique takes advantage of the insolubility of starch granules in water below 50 • C, which allows handling and processing at room temperature without affecting the structure.…”

Porous alumina ceramics prepared with wheat flour

“…When pure native starch is used, the difference is only about one order of magnitude. 23,34 The cell window size (pore throat diameter) measured here corresponds to that in porous ceramics prepared with pure native starch. 23,34 That means, the large pore cavities (cells with median diameters 120-240 m) are usually embedded in a matrix containing medium-sized pores (cells with medium diameters 20-29 m, i.e.…”

“…23,34 The cell window size (pore throat diameter) measured here corresponds to that in porous ceramics prepared with pure native starch. 23,34 That means, the large pore cavities (cells with median diameters 120-240 m) are usually embedded in a matrix containing medium-sized pores (cells with medium diameters 20-29 m, i.e. residual pores resulting from burnout of individual wheat starch granules), which are by themselves connected via small windows (with median diameters 1-2 m), cf.…”