Rheological and Structural Characterization of Ni–SiO2 Nanocomposites Produced by Aqueous Colloidal Processing
In this work, nickel–silica nanocomposites were fabricated via colloidal processing. A rheological approach was used to characterize and to optimize a 30 vol% nickel aqueous suspension with up to 10 vol% SiO2 nanoparticles.
The slurries showed a plastic and shear‐thinning behavior that retards sedimentation and facilitates the shaping of compacts. Slips were cast in plaster mold using ammonium polyacrylate as dispersant and tetramethylammonium hydroxide for adjusting the pH at 10.0 ± 0.1.
Green bodies were sintered at 900°C for 1 h in flowing argon/5% hydrogen atmosphere. Porous and dense materials were characterized by SEM/FE‐SEM, Archimedes’ densities, and Vicker's microhardness measurements. Composites showed homogeneous microstructure,
refined grain size, good densification (15 vol% pores), and hardness up to 250 Hv.