Effect of zirconia sol on the microstructure and properties of Al2O3-based ceramic fabricated from natural bauxite

Abstract

In this study, Al2O3-based ceramics were fabricated by adding zirconia sol into natural bauxite powder. With the addition of zirconia sol, the grain boundary migration during the sintering process was accelerated, numerous intracrystalline pores were then formed in materials. Due to the combined toughening effect of intracrystalline pores and secondary phase, the fracture toughness and flexural strength of material were increased. When adding 0.25 wt% zirconia sol, although the sample exhibited increased porosity, the fracture toughness and flexural strength were improved. However, the formation of intracrystalline pores is often accompanied with the formation of large intercrystalline pores, which are harmful to the mechanical properties of materials. With further increased zirconia sol addition, the mechanical properties of the samples decreased due to the further increase of porosity and pore size.