Postcasting Contraction: Improving the Density of Gelcast Nanoparticle Green Bodies with Heated Liquid Desiccants

Abstract

To achieve high‐density green bodies, a novel route without needing high solids loading suspensions, that is postcontraction process has been developed. In this process, the wet green body is immersed in heated liquid desiccants (polyethylene glycol [PEG] aqueous solution), which is prepared by gelcasting with thermoresponsive gel system. The density of green bodies is improved through releasing water quickly and shrinking rapidly. It is attributed to the cooperative action of the interior aggregation forces stemming from the shrinkage of network‐structured polymer and the exterior osmotic pressure from PEG aqueous solution. Alumina nanoparticle green bodies with different solids loadings were prepared by gelcasting with PNIPAM Poly(N‐isopropylacrylamide) gel system. The postcontraction process was almost completed in 30 min in liquid at 50°C, and meanwhile the bodies were almost dried. The relative densities of all green bodies and sintered parts are in accordance with each other, around 43% and 94%, respectively.