Abstract: Al2O3 ceramics were prepared by the gelcasting and pressure-less sintering method, with Al2O3 as starting powder, TiO2+MgO as sintering additives, agarose as the monomer, and ammonium polyacrylate as the dispersing agent.The solidification mechanism of agarose, sintering mechanism of sintering additive and the effect of the agarose content on the microstructure and mechanical properties of green body and sintered body were investigated.The experimental results show that the three-dimensional net structures form by means of abundant hydrogen bonds in the agarose.So the raw Al2O3 powders solidify.The TiO2+MgO sintering additive realize liquid sintering mechanism, so it is beneficial to reduce the sintering temperature and promote densification process.With increasing agarose content, both the flexure strength and relative density of green body and sintered body firstly increase and then decrease.The composite containing 0.5wt; agarose exhibits the highest flexure strength.

Key words: Al2O3 ceramics were prepared by the gelcasting and pressure-less sintering method, with Al2O3 as starting powder, TiO2+MgO as sintering additives, agarose as the monomer, and ammonium polyacrylate as the dispersing agent.The solidification mechanism of agarose, sintering mechanism of sintering additive and the effect of the agarose content on the microstructure and mechanical properties of green body and sintered body were investigated.The experimental results show that the three-dimensional net structures form by means of abundant hydrogen bonds in the agarose.So the raw Al2O3 powders solidify.The TiO2+MgO sintering additive realize liquid sintering mechanism, so it is beneficial to reduce the sintering temperature and promote densification process.With increasing agarose content, both the flexure strength and relative density of green body and sintered body firstly increase and then decrease.The composite containing 0.5wt; agarose exhibits the highest flexure strength.