Behaviour of different industrial ceramic pastes in extrusion process

It is well known that the extrudability of a ceramic paste is strongly dependent on materials composition and formulation, basically because it controls the resulting plasticity. Accordingly, the characterisation of the plastic behaviour is essential to adjust the fluxing properties of the material. In the current work, three industrially prepared ceramic pastes (porcelain, earthenware and terracotta) were tested, using stress-deformation curves obtained by compression of cylindrical probe tests. To achieve good extrusion performance, the design and operating conditions also need to be considered in detail. The ram extrusion of adjusted pastes was followed by the Benbow-Bridgwater model. Differences in the flow behaviour were related with stress-deformation curves and with the surface quality of the extrudate (by using the static friction coefficient).