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TiC/Si_3N_4 composites were prepared using theβ-Si_3N_4 powder synthesized by self-propagating high-temperature synthesis(SHS)and 35 wt.% TiC by spark plasma sintering.Y_2O_3 and Al_2O_3 were added as sintering additives.The almost full sintered density and the highest fracture toughness(8.48 MPa·m~(1/2))values of Si_3N_4-based ceramics could be achieved at 1550℃.No interfacial interactions were noticeable between TiC and Si_3N_4.The toughening mechanisms in TiC/Si_3N_4 composites were attributed to crack deflection,microcrack toughening, and crack impedance by the periodic compressive stress in the Si_3N_4 matrix.However,increasing microcracks easily led to excessive con- nection of microcracks,which would not be beneficial to the strength.
TiC / Si_3N_4 composites were prepared using the β-Si_3N_4 powder synthesized by self-propagating high-temperature synthesis (SHS) and 35 wt.% TiC by spark plasma sintering. Y_2O_3 and Al_2O_3 were added as sintering additives.The almost full sintered density and the highest fracture toughness (8.48 MPa · m ~ (1/2)) values of Si_3N_4-based ceramics could be achieved at 1550 ℃ .No interfacial interactions were noticeable between TiC and Si_3N_4.The toughening mechanisms in TiC / Si_3N_4 composites were attributed to crack deflection, microcrack toughening, and crack impedance by the periodic compressive stress in the Si_3N_4 matrix. Still, increasing microcracks led to excessive con- nection of microcracks, which would not be beneficial to the strength.