可加工BN/B_4C复相陶瓷的制备与其抗热震性能

采用热压烧结工艺制备了BN/B4C微米复相陶瓷和BN/B4C纳米复相陶瓷。由淬水法测试了单相B4C陶瓷,BN/B4C微米复相陶瓷和BN/B4C纳米复相陶瓷的抗热震性能,用三点弯曲法测试了热震后样品的抗弯强度。结果表明:BN/B4C微米复相陶瓷和BN/B4C纳米复相陶瓷的抗热震性能明显高于单相B4C陶瓷的抗热震性能,而且BN/B4C纳米复相陶瓷的抗热震性能明显高于BN/B4C微米复相陶瓷的抗热震性能。BN/B4C微米复相陶瓷和BN/B4C纳米复相陶瓷具有良好的抗热震性能主要是由于具有较高的抗弯强度和较低的弹性模量;同时BN/B4C复相陶瓷中的BN/B4C弱界面和层状结构的h-BN晶粒能够显著提高复相陶瓷的抗热震性能。

FABRICATION AND THERMAL SHOCK RESISTANCE OF THE MACHINABLE BN/B4C COMPOSITE CERAMICS

BN/B4C micro-composite and BN/B4C nano-composite were fabricated by hot-pressing process. The thermal shock resistances of the BN/B4C micro-composite and the BN/B4C nano-composite were investigated by the water-quenching method compared with the B4C monolith ceramic. The residual fracture strength after thermal shock test was measured by the three-point bending method. The results show that the thermal shock resistances of the BN/B4C micro-composite and the BN/B4C nano-composite are much better than that of the B4C monolith ceramic. The thermal shock resistance of the BN/B4C nano-composite is much better than that of the BN/B4C micro-composite. The high thermal shock resistances of the BN/B4C micro-composite and the BN/B4C nano-composite can be attributed to their high fracture strength and low modulus of elasticity modulus. The microstructure analysis shows that the weak interface of BN/B4C and cleavage behavior of laminate-structured h-BN particles can remarkably improve the thermal shock resistance of the BN/B4C composites.