Colloidal processing of highly concentrated aqueous copper suspensions

This work deals with the preparation of copper dense compacts using an aqueous colloidal route. Concentrated suspensions of Cu powders were prepared in water with a polyelectrolyte and tetramethylammonium hydroxide at alkaline pH as dispersing agents. Suspensions were optimized by measuring the rheological behavior as a function of pH and volume fraction of solids. The slurries showed a pseudoplastic behavior with thixotropy due to the additives added. The suspensions were slip cast in plaster molds leading to high green densities (~ 61% TD), as a consequence of the particlesʹ shape and size distribution packing characteristics. Sintering studies were performed at 900 °C in flowing Ar/5% H2 atmosphere. The green and dense compacts shaped by this route were characterized by SEM and Archimedesʹ density.