Air permeable alumina-based porous ceramics with high performance prepared by novel gel casting route

In the present work, porous ceramics with open pores were fabricated using the gel casting method, which utilizes carrageenan as a cross-linking agent. Beyond the foaming agents or templates techniques, this approach employed large-sized Al 2 O 3 particles (~ 45 μm) as the underlying framework material, enabling the direct formation of minute open pores within the green bodies and sintered samples. In order to finely adjust the pore structure and bolster flexural strength, micropowders of α-Al 2 O 3 and Kaolin were incorporated as filling materials, alongside the introduction of rare-earth oxides as sintering additives. The study diligently examined the impact of varying the content of sintering additives as well as the sintering temperatures on the characteristics of the porous ceramics. As a result, remarkable achievements were obtained, culminating in the production of Al 2 O 3 -based porous ceramics measuring 8 mm in thickness, exhibiting flexural strength exceeding 160 MPa, porosity surpassing 30%, and exceptional gas permeability of over 30 L/min/cm 2 under a pressure drop of 100 kPa.