INVESTIGATION OF RHEOLOGICAL PROPERTIES OF FEEDSTOCK USING THE BACKBONE BINDER POLYPROPYLENE FOR INJECTION MOLDING OF IN718 SUPERALLOY POWDER

In this study, optimum rheological properties for powder injection molding (pim) of in718 powder, widely usedin aerospace industry, were determined. the feedstocks were prepared 61, 63 and 65% (volume) powder loadingrates with three different binding cures using polypropylene as backbone binder.the mean particle size of usedin718 powder was 13.40 microns. components used in the binding (polyethylene glycol, paraffin wax,carnauba wax, stearic acid and polypropylene ) were mixed for 30 minutes as dry in three dimensional mixerto prepare binder cures. rheological properties of feedstock were characterized by using a capillary rheometer.in this experimental studies, shear stress (τ), shear rates (gamma), viscosity (η), flow behavior index (n) and the flowactivation energies (ea) of feedstocks were determined depending on the temperature and pressure.temperatures and pressure values of capillary rheometer changed 130-200°c and 0.165-2.069 mpa,respectively. shear stress (τ of pim feedstocks determined between 10.8-135.3 kpa. apparent shear rates (gamma) ofpim feedstocks were found to be 6.890-814.718 s^-1. apparent viscosities of feedstocks were calculated within the range 55.349-1571.707 pa.s depending on the temperature, binder formula, shear stress and shear rate. theflow behavior index (n) parameters for pim feedstocks were determined to be less than 1. effects of temperatureonto apparent viscosities of feedstocks were also studied and flow activation energies under various shearstresses were determined within the range of 11.750-51.958 kj/mol.