A water-soluble epoxy resin and hardener system for gelcasting of ceramics was developed. Polymerization of the system is a nucleophilic addition reaction, and not affected by oxygen. Therefore, this gelcasting system can be carried out in an air atmosphere. The ceramic slurries were prepared by mixing the aqueous premix solution of epoxy resin with alumina powder and dispersant. For cross-linking, a polyamine hardener was added. Both the rheological properties of the slurries and the gelling behaviors of the aqueous premix solutions were evaluated. The slurry with a solid loading of 80 wt% is optimized for gelcasting. The flexural strength of the sintered ceramics is 335747 MPa with 98% of theoretical density.

Abstract

Transparent aluminum oxynitride (AlON) ceramics have been prepared through aqueous gelcasting forming technique starting from the raw materials of single phase AlON powders. The powder was specially treated for anti‐hydrolysis in ethanol before the shaping technique. The surface‐treated AlON powders could then be dispersed in an aqueous‐organic solution to prepare stable slurries containing 35 vol% solids loading. The obtained stable slurries were subsequently casted, calcined, and pressureless sintered at 1950°C for 8 h in nitrogen atmosphere. High transparent AlON ceramics with an average grain size of 112 μm and the in‐line transmittance of 81% at wavelength 1100 nm have been obtained.