Properties of Alumina Coagulated Bodies Prepared by Direct Coagulation Casting via High Valence Counter Ions (DCC‐HVCI)

Abstract

Alumina green bodies were prepared by direct coagulation casting via increasing high valence counter ions (DCC‐HVCI) method. Influence of calcium iodate concentration, coagulation temperature, and the solid loading on the compressive strength of coagulated bodies was investigated. The results show that the wet‐coagulated bodies display higher compressive strength than dried ones. The wet strength is above 2.0 MPa which is about one order higher than that prepared by DCC method, whereas the dried strength is in the range of 1.0 MPa. The wet‐coagulated body shows elastic deformation, whereas the dried body exhibits typical brittle failure behavior. The mechanism of high wet strength obtained by DCC‐HVCI is also proposed. The coagulated bodies prepared from slurries of alumina loading in the range of 50 vol% showed linear shrinkage of 2.6% after drying at 80°C for 24 h. The sample with the powder content of 50 vol% displays a narrow average pore channel size, showing a mean pore diameter of 40 nm. A homogeneous green body and high wet strength can be obtained via the DCC‐HVCI method.