Role of the clogging effect in the slip casting process

Particle segregation phenomena occurring during consolidation of the green bodies lead to non-homogeneous microstructures and poor reliability of the ceramic components. The two driving forces responsible for particle segregation in the slip casting process are the gravity force and the capillary suction of the plaster moulds. Both segregation mechanisms depend on other factors such as particle density, particle size distribution, particle interaction forces, and solid loading. The relative importance of each segregation mechanism was investigated by? using two commercial silicon carbide powders having different particle size distributions, as well as different colours. The effects of the interparticle forces, solid loading and the driving force of the slip casting process Ir cre studied. The results obtained showed that for moderately concentrated suspensions and a driving force given by the capillary suction of the plaster moulds, the clogging effect plays the main role in particle segregation, whilst sedimentation predominates for low driving forces. Inadequacy of the existing models to explain the clogging effect is discussed and a new model is proposed. (C) 1998 Elsevier Science Limited. All rights reserved.