Effect of talc and titania on the microstructure and mechanical properties of alumina ceramics

Alumina (Al 2 O 3 ) ceramics were prepared with nucleating agent of titania (TiO 2 ) and fluxing agent of talc by the normal pressure sintering method. The effects of TiO 2 and talc on phase composition, microstructure, and mechanical properties of Al 2 O 3 ceramics, as well the strengthening and toughening mechanism were investigated. It was found that the introduction of TiO 2 could be favorable for mullite formation and the improved densification of ceramics, resulting in improved mechanical properties of ceramics as well. Ceramics possess the best comprehensive mechanical performance with fracture toughness of 3.69 MPa·m 1/2 and flexural strength of 255.9 MPa when 4 wt.% TiO 2 and 15 wt.% talc were added. Mineral bridges and nanocrystallites were found in the glass-ceramics, which caused the deflection of cracks so that it strengthened the grain boundary and improved the mechanical properties of ceramics.