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Bidirectional Freeze Casting

TITLEA and B: Unidirectional freeze casting generates lamellar structure aligned in only one direction because the particles are assembled under single temperature gradient. C and D: Bidirectional freeze casting generates large scale lamellar structure aligned in two directions because the particles are assembled under dual temperature gradients.

Scientific Achievement
Processing of ceramic scaffolds with large-scale aligned lamellar porous, nacre-like structure, and long-range order at the centimeter scale have been achieved.

Significance and Impact
This approach could provide an effective way of manufacturing novel bioinspired structural materials, in particular advanced materials such as composites, where a higher level of control over the structure is required.

Research Details

  • A polydimethylsiloxane wedge with different slopes was placed in between the cold finger and the ceramic slurry, which generates dual temperature gradients.
  • Gradient nucleation and propagation of ice crystals were achieved under such gradients.
  • Bidirectional freeze casting can manipulate alignment of ice crystals in two directions, and can be applied to generate larger porous scaffolds with highly controlled, ordered structures.

H. Bai, F. Walsh, B. Gludovatz, B. Delattre, C. Huang, Y, Chen, A. P. Tomsia & R. O. Ritchie, Advanced Materials (2015)