CNTs的添加对纳米Si_3N_4陶瓷组织与力学性能的影响

Effect of CNTs on Microstructure and Mechanical Properties of Si_3N_4 Nano-ceramic

采用热压烧结法制备了CNTs-Si3N4纳米复相陶瓷,研究了碳纳米管(CNTs)的添加对Si3N4陶瓷组织与力学性能的影响,用XRD分析了该复合材料的相组成,并对它的硬度、抗弯强度和断裂韧性进行了测试。结果表明,CNTs-Si3N4纳米复相陶瓷的相为α-Si3N4、β-Si3N4和Si2N2O;其抗弯强度和断裂韧性均随碳纳米管含量的增加呈先升后降的变化趋势,最大值分别在CNTs添加量为2wt%和4wt%时获得;CNTs添加量为2wt%时,硬度略有提高,然后随碳纳米管含量的继续增加而逐渐降低;CNTs-Si3N4纳米复相陶瓷的主要增韧机制为碳纳米管的拔出、桥联和裂纹偏转。

CNTs-Si3N4 nano-composite ceramic was fabricated by hot press sintering.The effects of CNTs on the microstructure and mechanical properties of Si3N4 nano-ceramics were investigated.The phase composition of the compound ceramic was investigated by XRD.The hardness,bending strength and fracture toughness of the compound ceramic was measured.The results show that the main phases in CNTs-Si3N4 nano-composite ceramic are α-Si3N4,β-Si3N4 and Si2N2O.The fracture toughness and flexural strength firstly increase with the increase of carbon nano-tube content and then decrease,and the maximum fracture toughness and flexural strength are obtained when the content of carbon nano-tube is 4wt% and 2wt%,respectively.The hardness has a little increase when the amount of carbon nano-tubes is 2wt%,then gradually decreases with the increase of carbon nano-tube content.The main toughening mechanism of CNTs-Si3N4 nano-composite ceramics is the extraction of CNTs,the bridging of CNTs and crack deflection.