Study on gelcasting of silicon nitride-bonded silicon carbide refractories

Abstract

Gelcasting is a very useful technique for producing ceramic green parts with near-net-shapes. Although it has been successfully applied to shape fine ceramic systems where micrometer- and submicrometer-size particles are used as starting powders, there is little report on gelcasting of refractories manufactured by coarse raw materials. In the present paper, dispersion and rheological properties of concentrated suspensions of SiC/Si mixtures with coarse particles (∼350 μm) and their gelcasting processes were discussed. A stable SiC/Si suspension with solids loading up to 70 vol.% was prepared, from which uniform green bodies with complex shapes were successfully gelcast. The performances of green bodies and sintered samples were measured and their microstructures were studied. After nitridation of the gelcast components at 1450 °C for 10 h in 0.1 MPa nitrogen atmosphere, the bulk density of 2.61 g cm −3 and flexural strength of 55.4 MPa were obtained.