RHEOLOGICAL BEHAVIOR OF POWDER INJECTION-MOLDING MODEL SLURRIES

Slurries used in powder injection molding are typically made from high density fillers suspended in a molten wax or other carriers. Particle size and density and base fluid viscosity are the main experimental variables in this work. Slip corrections were made on all of the data for slurries of greater than 20 vol % solids content. Tests are reported on particles that cover a fivefold particle radius range. The data reflect a 1/r dependence on the particle radius. Particle densities range from 2.7 to 19.3 g/cm3. The data show a strong dependence on density. Base fluid viscosities range from 20 to 250 P, and it is shown that higher base-fluid viscosities result in lower particle concentration effects on the relative fluid viscosity of the slurry. Rheological data are shown to be a function of the mean interparticle spacing, and plots of the relative viscosity versus the mean interparticle spacing exhibit an interesting convergence at about 150-mu.