On the modelling of non-monotonous viscosity describing feedstock behaviour in powder injection moulding

Abstract

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.

Feedstocks used in the process of powder injection moulding characterized by the flow of highly filled (60 vol.%) compound into a mould cavity, sometimes exhibit non- monotonous flow behaviour of viscosity in dependence on shear rate. A new 7-parameter rheological model was proposed and applied to the feedstock based on aluminium oxide powder and multicomponent partly water-soluble polymeric binder. Structural changes of the feedstock caused by shear deformation were quantified in terms of yield stresses obtained using the classical monotonous Herschel-Bulkley and Casson models. Unlike these models the newly proposed 7-parameter rheological model is valid in the whole shear rate range measured.