Effect of plate-like alumina seed on the fracture toughness of alumina ceramics

The effects of plate-like alumina seed amount on the microstructure and properties of alumina ceramics prepared by pressureless sintering were studied,when plate-like alumina seed was used as the second phase.The effects of plate-like alumina content on the microstructure of fracture surface of alumina ceramics were studied by SEM.The fracture toughness(KIC) of specimen was calculated by the indentation method and the effects of crystal seed with different contents on the fracture toughness of alumina ceramic were studied.The results demonstrate that the relative density of alumina ceramics reaches 96.7% when sintering temperature is 1575℃.The fracture toughness of alumina ceramics increases gradually as crack deflection and plate-like alumina seed pullout working.With the content of the plate-like alumina increasing,the mechanical properties of alumina ceramic gradually increased.When 35wt % seeds were added,the fracture toughness can reach 6.4MPa·m1/2