Preparation and characterisation of metal powder slurries for use as precursors for metal foams made by gel casting

Abstract

Metal powder slurries were prepared by adding 316L stainless steel powder to a methylcellulose solution. The highly viscous solution, in combination with high particle loadings, hindered powder sedimentation. The efficacy of a dispersant to produce low viscosity slurry was assessed by measuring the torque required to stir the suspension, compared to that needed to stir the base solution under the same conditions. These measurements were in reasonable agreement with data from viscometry, indicating a dispersant addition of 1·5 wt-% (based on the mass of the powder added) was sufficient to reduce the viscosity to that for the base cellulose solution. Slurries containing 45 vol.-% of 316L powder in a 2 wt-% methylcellulose solution, to which a minimum of 1·5 wt-% dispersant had been added, had a viscosity of roughly 0·5 Pa s and is deemed suitable for the production of metal foams via dipping or by mechanical whisking methods.