采用放电等离子烧结技术(SPS)快速烧结了SiC晶须增强的Si3N4/BN层状复合材料.利用SPS技术,在烧结温度为1650℃、保温15min的条件下,材料的密度可达3.18g/cm3,抗弯强度高达600MPa,断裂功达到3500J/m2.研究表明:特殊的层状结构、SiC晶须的拔出与折断是材料断裂功提高的主要原因.X射线衍射及扫描电子显微镜研究表明:α-Si3N4已经在短短的烧结过程中全部转变成长柱状的β-Si3N4,并且长柱状的β-Si3N4和SiC晶须具有明显的织构.
SiC whisker reinforced laminated Si3N4/BN ceramics with additives Y2O3, Al2O3 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.
参考文献
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