Electrophoretic deposition and freeze casting

The shaping method of electrophoretic deposition uses the transport and the deposition of charged powder particles from suspensions under the influence of an electrical field. The outstanding advantage of this shaping method can be seen in the very homogeneous particle packing which can be attained in the ceramic green body. Electrophoretic deposition demands the development of stable suspensions with high particle surface charges. It is mainly used for producing thin-walled parts or coatings.

For freeze casting aqueous ceramic suspensions are frozen in a dye. Depending on the freezing conditions and the additives given to the suspension the suspension medium forms various ice crystals. Afterwards, the suspension medium is removed from the shaped body by sublimation drying. Owing to the fact that no capillary forces are acting during the sublimation process, the green parts show zero shrinkage during the drying step. After freeze drying the shape of the ice crystals is replicated in the pore structure. This offers the possibility to produce components with complex geometry and defined pore shape. Moreover, it is possible to achieve material compounds consisting of two ceramics showing novel pore structures.

 

Products and services offered

 

• Development and optimization of suspensions
  
• Electrophoretic deposition
  
• Freeze drying
  
• Freeze casting
  
• Spray freeze granulation

 

Examples and references

 

• Electrophoretically deposited dental crowns and bridges
  
• Development of optimized suspensions suitable for electrophoretical deposition
  
• Freeze cast bone scaffolds made of hydroxylapatite
  
• Freeze cast dental parts
  
• Freeze casting in ice molds and with ice cores
  
• Spray freeze granulation of ceramic suspensions for the manufacture of very soft, redispersable granules