Search

Gelcasting is a colloidal processing method for fabricating high-strength and complex shape ceramic green bodies. However, industry has been reluctant to use the gelcasting technique because the most commonly used gel, acrylamide ( AM), is a neurotoxin. Here, we report an attempt at the gelcasting of fused silica glass using a natural and nontoxic gel, glutinous rice flour ( GRF) as binder. The GRF-based aqueous system was found to behave excellently in the gelcasting process. Flexural strength of fused silica green bodies solidified with only 3 wt% GRF is up to 11.87 MPa. Bulk density and flexural strength of fused silica glass sintered at 1275 °C are 1.75 g/cm3 and 47.02 MPa, respectively. [ABSTRACT FROM AUTHOR]

Fused silica ceramics were fabricated by gelcasting, by use of a low-toxicity N′ N-dimethylacrylamide gel system, and had excellent properties compared with those obtained by use of the low-toxicity 2-hydroxyethyl methacrylate and toxic acrylamide systems. The effect of sintering temperature on the microstructure, mechanical and dielectric properties, and thermal shock resistance of the fused silica ceramics was investigated. The results showed that sintering temperature has a critical effect. Use of an appropriate sintering temperature will promote densification and improve the strength, thermal shock resistance, and dielectric properties of fused silica ceramics. However, excessively high sintering temperature will greatly facilitate crystallization of amorphous silica and result in more cristobalite in the sample, which will cause deterioration of these properties. Fused silica ceramics sintered at 1275°C have the maximum flexural strength, as high as 81.32 MPa, but, simultaneously, a high coefficient of linear expansion (2.56 × 10/K at 800°C) and dramatically reduced residual flexural strength after thermal shock (600°C). Fused silica ceramics sintered at 1250°C have excellent properties, relatively high and similar flexural strength before (67.43 MPa) and after thermal shock (65.45 MPa), a dielectric constant of 3.34, and the lowest dielectric loss of 1.20 × 10 (at 1 MHz). [ABSTRACT FROM AUTHOR]