Porous Ceramics

Abstract

The unique chemical composition and microstructure of porous ceramics enable the ceramic products used in a number of applications such as filtration of molten metals and hot corrosive gases, high-temperature thermal insulation, support for catalytic reactions, filtration of diesel engine exhaust gases, etc. These applications take advantage of special characteristics of porous ceramics such as low thermal mass, low thermal conductivity, controlled permeability, high surface area, low density, and high specific strength. In this chapter, we emphasize on direct foaming method, a simple and versatile approach that allows fabrication of porous ceramics with tailored microstructure along with distinctive properties. Foam stability is achieved upon controlled addition of amphiphiles to the colloidal suspension, which induce in situ hydrophobization, allowing the wet foam to resist coarsening upon drying and sintering.

Sintering behavior of magnesium aluminate spinel MgAl2O4 synthesized by different methods

“…This shift reflects the increase in surface acidity of the Al 2 O 3 material. From this result, we can admit that the shift observed in our experiment is somewhat similar to that observed by Sarkar and Kim in their works. However, the MgO particles remain constant Zeta‐potential values ( ζ ≈ 15 mV) in the range of 4‐10 pH.…”

“…From Figure , we can also see that the Al 2 O 3 ζ ‐signal is mainly located in the range of 4‐12 pH, suggesting that the surface of Al 2 O 3 particles is negative and the cation is adsorbed. According to the literature, the IEP of Al 2 O 3 is found in the range of 4.5‐9.7 pH . Based on the work of Sarkar and Kim, the Zeta potential profile of Al 2 O 3 is shifted to lower pH values (with also an IEP shift from 6 to 4.5 pH) according to the use of particle sizes from 6 to 4 μm.…”

“…According to the literature, the IEP of Al 2 O 3 is found in the range of 4.5‐9.7 pH . Based on the work of Sarkar and Kim, the Zeta potential profile of Al 2 O 3 is shifted to lower pH values (with also an IEP shift from 6 to 4.5 pH) according to the use of particle sizes from 6 to 4 μm. This shift reflects the increase in surface acidity of the Al 2 O 3 material.…”

Porous alumina ceramics by gel casting: Effect of type of sacrificial template on the properties

“…Ceramics offer advantages compared to other materials such as polymers and metals, such as hardness, chemical inertness, thermal shock resistance, corrosion, and wear resistance . Addition of porosity to ceramics introduces low thermal mass, low thermal conductivity, controlled permeability, high surface area, low density, and high specific strength . These added properties make the porous ceramics attractive to be used widely in various versatile applications like filters for diesel emissions, molten metal filters, high‐temperature thermal insulation, membrane reactors, and catalyst supports .…”

“…Addition of porosity to ceramics introduces low thermal mass, low thermal conductivity, controlled permeability, high surface area, low density, and high specific strength . These added properties make the porous ceramics attractive to be used widely in various versatile applications like filters for diesel emissions, molten metal filters, high‐temperature thermal insulation, membrane reactors, and catalyst supports . Wet processing route in the processing of porous ceramic is promising compared to the dry processing route since it offers better control on particle‐particle interactions and homogeneity of particles, which lead to fewer defects in the ceramic microstructure .…”