Extrusion of alumina ceramic tubes with controlled bends

An extrusion die was introduced in which the internal geometry of the die could be controlled through a simple computer interface to produce alumina tubes with varyingly controlled bends. The relationship between the paste rheology and the bending behaviour is addressed through a detailed analysis of the rheological flow behaviour, such as paste composition and viscosity as well as the nature of the liquid binders. It is shown that the curvature of the tube is controlled by paste composition and binder rheological properties and the degree of bend increases with increasing viscosity of the paste (the greater the solids loading the greater the curvature). C 2005 Springer Science + Business Media, Inc.