Fabrication of SiC Whisker Reinforced Laminated Si_3N_4 /BN Ceramics by Spark Plasma Sintering

SiC whisker reinforced laminated Si3N4/BN ceramics with additives Y2O3, A12O3 and MgO were prepared by spark plasma sintering(SPS) in 13min of heating to 1650℃ and 15min dwell time. The density of the samples densified by SPS was 3.18g/cm3. Bending strength reached 600 MPa, and the work of fracture reached 3500 J/m2. The arrangement of hard Si3N4 layer and soft BN layer, the pull-out and broken of SiC whisker were the main reason for improving toughness of this ceramic. XRD and SEM indicated SiC whisker, long rod like β-Si3N4 and platelet like hex-BN were the main phase and SiC whisker, long rod like β-Si3N4 had strong preferred orientation.