摘要
Novel ZTA/Al 2O 3 SiC w TiC polyphase ceramics were fabricated by hot pressing techniques. Phase transformation toughening, particle dispersion and whisker reinforcement have obviously superposed strengthening and toughening effects. It is observed that ZTA 20SiC w 20TiC has better comprehensive mechanical properties compared with Al 2O 3 20SiC w 20TiC. For the optimum processing, the ZTA 20SiC w 20TiC exhibited a flexural strength of 567MPa, a fracture toughness of 6.3MPa·m 0.5 , a hardness of HRA93.6 and a relative density of ≥99.6%. The tensile stress in matrix introduced by SiC whisker and TiC could be relaxed by the compress stress produced by tetragonal zirconia(ZrO 2(t)) transformation. TiC formed a continuous skeleton which prevented the grain growth of the matrix. The grain sizes of the matrix became finer with increasing TiC. The major fracture mode of the matrix was transcrystalline cleavage rupture.
Novel ZTA/Al 2O 3 SiC w TiC polyphase ceramics were fabricated by hot pressing techniques. Phase transformation toughening, particle dispersion and whisker reinforcement have obviously superposed strengthening and toughening effects. It is observed that ZTA 20SiC w 20TiC has better comprehensive mechanical properties compared with Al 2O 3 20SiC w 20TiC. For the optimum processing, the ZTA 20SiC w 20TiC exhibited a flexural strength of 567MPa, a fracture toughness of 6.3MPa·m 0.5 , a hardness of HRA93.6 and a relative density of ≥99.6%. The tensile stress in matrix introduced by SiC whisker and TiC could be relaxed by the compress stress produced by tetragonal zirconia(ZrO 2(t)) transformation. TiC formed a continuous skeleton which prevented the grain growth of the matrix. The grain sizes of the matrix became finer with increasing TiC. The major fracture mode of the matrix was transcrystalline cleavage rupture.
基金
theYoungScienceFoundationofShanghaiMunicipalCommissionofEducation!( 98QN5 5 )
