Rheological properties of nanosized AlN powder suspensions for advanced ceramics

The rheological properties (flow curves and viscoelastic behavior) of injection molding suspensions of a plasma-processed AlN nanosized powder (nanopowder) in paraffin are investigated over a broad range of shear rates (0.07-1350 s exp -1 ). Two viscosity plateaux are observed on the flow curves and two values of the yield stress are obtained. The lower value of the strain amplitude (0.66%), exceeding the linearly limit of periodic shear, is restricted by the rheometer resolution. The ultrasound treatment and shear deformation of suspensions affect the structure of particle packing, which is responsible for the dependence of their rheological properties on the prehistory of mechanical actions.