LAUSR

Abstract Gelcasting method with nontoxic biopolymer as gel former can be used to prepare ceramics with complex shape. AlN ceramic bonded carbon (AlN/CBC) composites with light weight were fabricated by gelcasting and pressureless sintering method using nontoxic agarose as gel former with Y2O3 + CaF2 as sintering additive. The effect of sintering additive content and sintering temperature on the microstructure, flexural strength and thermal conductivity of composites was investigated. The results reveal that, as the temperature decreases, the raw powders solidify into three-dimensional net structures through abundant hydrogen bonds in the agarose. High sintering temperature facilitates densification and improves mechanical and thermal properties of the composites. Increasing sintering additive content can also tune the density and raise flexural strength. The AlN/CBC composite containing 7 wt% sintering additive content, which was sintered at 2000 °C, exhibits the highest thermal conductivity. Relative density, C content and microstructure uniformity have effects on properties of AlN/CBC composite.