Freezing Dilute Ceramic/Camphene Slurry for Ultra‐High Porosity Ceramics with Completely Interconnected Pore Networks

Highly porous alumina ceramics with completely interconnected pore channels were fabricated by freezing dilute alumina/camphene slurries with solid loadings ranging from 5 to 20 vol%. This method fundamentally made full use of the three-dimensional camphene dendritic network for producing interconnected pore channels and the concentrated alumina powder network for achieving dense alumina walls. Firstly, alumina/camphene slurries were prepared at 60°C using ball milling and then cast into molds at 20°C. After subliming the frozen camphene, the samples were sintered at 1400°C for 5 h. This method enabled us to freeze very dilute ceramic slurries with a low solid loading of ≤20 vol% without the collapse of the sample after sintering. As the initial solid loading decreased from 20 to 5 vol%, the porosity linearly increased from 66% to 90% with an increase in the pore size, while completely interconnected pore networks were obtained in all cases. In addition, the free surfaces of the alumina walls showed full densification after sintering even at a low temperature of 1400°C, while some pores were present in the inner regions of the alumina walls.

[1]  S. H. Lee,et al.  Improved compressive strength of reticulated porous zirconia using carbon coated polymeric sponge as novel template , 2006 .

[2]  H. Bahn,et al.  Fabrication of a Porous Bioactive Glass–Ceramic Using Room-Temperature Freeze Casting , 2006 .

[3]  J. Halloran,et al.  Particle Redistribution During Dendritic Solidification of Particle Suspensions , 2006 .

[4]  Hyoun‐Ee Kim,et al.  In situ Fabrication of a Dense/Porous Bi‐layered Ceramic Composite using Freeze Casting of a Ceramic–Camphene Slurry , 2006 .

[5]  Eduardo Saiz,et al.  Freezing as a Path to Build Complex Composites , 2006, Science.

[6]  Suresh C. Sharma,et al.  A Novel Process for Low‐Density Alumina Foams , 2005 .

[7]  J. Halloran,et al.  Porous Ceramic Bodies with Interconnected Pore Channels by a Novel Freeze Casting Technique , 2005 .

[8]  J. Halloran,et al.  New Freeze‐Casting Technique for Ceramics with Sublimable Vehicles , 2005 .

[9]  P. Colombo,et al.  Micro-/Macroporous Ceramics from Preceramic Precursors , 2004 .

[10]  Guo‐Jun Zhang,et al.  Fabrication of Porous Ceramics with Unidirectionally Aligned Continuous Pores , 2004 .

[11]  P. Bhargava,et al.  Effect of Sucrose on Fabrication of Ceramic Foams from Aqueous Slurries , 2004 .

[12]  S. Dhara,et al.  A Simple Direct Casting Route to Ceramic Foams , 2003 .

[13]  J. Vohs,et al.  Synthesis of Highly Porous Yttria‐Stabilized Zirconia by Tape‐Casting Methods , 2003 .

[14]  J. Binner,et al.  Processing of cellular ceramics by foaming and in situ polymerisation of organic monomers , 1999 .

[15]  Sridhar Komarneni,et al.  Porous Materials: Process technology and applications , 1998 .

[16]  N. Minh.  Ceramic Fuel Cells , 1993 .

[17]  S. Kanzaki,et al.  Synthesis of Porous Ceramics with Complex Pore Structure by Freeze‐Dry Processing , 2001 .

[18]  John Evans,et al.  Porous ceramics prepared from aqueous foams , 1999 .

[19]  José M.F. Ferreira,et al.  Processing of porous ceramics by ‘starch consolidation’ , 1998 .

[20]  M. Ashby,et al.  Cellular solids: Structure & properties , 1988 .