Freeze casting for near-net-shaping of dense zirconium diboride ceramics

Abstract

Zirconium diboride (ZrB2) was formed into dense complex shapes using freeze casting as a near-net-shaping technique. Aqueous-based formulations were compared with nonaqueous (cyclohexane) based formulations in terms of rheological behavior, particle packing in the green body, sintered density, macroscale porosity, and cracking. The influence of particle solids concentration and freezing rate was investigated. The aqueous formulations were found to be deficient in that they produced macroscale porosity that could not be eliminated during sintering resulting in low density and large pores in the final shaped objects. The nonaqueous-based system was able to produce complex shaped objects with s..