Influence of Solid Loading and Ratio of Monomers on Mechanical and Dielectric Properties of Hybrid Ceramic Composites

Hybrid ceramic (SiO2-Si3N4-Al2O3) composites were prepared by gel casting process, a near net shape technique. The effects of solid loading and monomers ratio on flexural strength, porosity, room temperature dielectric properties and thermal conductivity were investigated. Methylacrylamide (MAM) and N, N1- methylenebisacrylamide (MBAM) were used as monomers because of their low toxicity. The hybrid ceramics were sintered to a temperature of 1250 °C and the monomer content kept constant at 10 wt%. The flexural strength of the ceramics increases and porosity decreases with increase in solid loading. The flexural strength increases up to a certain stage and then decreases by showing an optimum point at monomer ratio of 10:1. The maximum flexural strength and minimum porosity obtained were 95.12 MPa, and 28.5% respectively. The dielectric constant and dielectric loss were increased slightly by the addition of Si3N4-Al2O3 and found to be 4.822 and 0.00351 at a frequency of 30 MHz at room temperature. The minimum thermal conductivity at room temperature of the composite was found to be 0.2131 W/mK.