Effect of solid loading on gelcasting of silica ceramics using DMAA

Silica ceramics with low porosity, high strength, low dielectric constant and loss were fabricated by gelcasting using a low-toxicity N′N-dimethyl acrylamide (DMAA) gel system. Effect of solid loading on rheological properties of slurries, properties of green bodies and sintered ceramics were investigated. The solid loading of suspension that can meet requirements for casting is as high as 68 vol%. However, it is found that the highest flexural strength of 15.4 MPa for green bodies and 67.4 MPa for sintered ceramics is obtained at the solid loading of 64 vol% and 66 vol%, respectively. Ceramics with dielectric constant of 3.27 and the lowest dielectric loss (1 MHz) of 7.82×10–4 are obtained at the solid loading of 64 vol%. Solid loading has a critical effect on properties of green and sintered silica bodies.