Optimization of a Nanoparticle Suspension for Freeze Casting

Poly(acrylic acid) (PAA) dispersant concentration, suspension pH, and Al 2 O 3 solids loading effects on PAA adsorption onto Al 2 O 3 nanoparticles were studied; the stability and rheology of the Al 2 O 3 nanoparticle suspensions were examined. The most desirable suspension conditions were 7.5–9.5 for pH and 2.00–2.25 wt% of Al 2 O 3 for the PAA concentration. Electrical double‐layer thickness and PAA adsorption layer thickness comparison showed that electrosteric stabilization was dominant. 45.0 vol% Al 2 O 3 solids loading can be achieved for freeze casting. The maximum solids loading was predicted to be 50.7 vol%. The freeze‐cast sample showed that pre‐rest before freezing was critical for achieving desirable microstructures.