碳纳米管分散增强AlN基复合材料的力学性能及增韧机制研究

Mechanical properties and toughening mechanisms of well-dispersed carbon nanotubes reinforced AlN-based composites

文章以氮化铝(AlN)粉末为基体材料,以氧化钙(CaO)和氧化钇(Y2O3)为烧结助剂,掺杂酸洗处理后的多壁碳纳米管(CNTs)为增韧材料,采用机械球磨后热压烧结的方法制备氮化铝-碳纳米管(AlN-CNTs)复合材料。通过X射线衍射仪(X-ray diffraction,XRD)和扫描电子显微镜(scanning electron microscope,SEM)对AlN-CNTs复合材料的成分结构及微观形貌进行表征,并测试其物理力学性能。研究表明:随着烧结温度的升高,AlN-CNTs复合材料的力学性能也随之提升;在1750℃的烧结温度下,随着碳纳米管质量分数的增加,AlN-CNTs复合材料的抗弯强度和断裂韧性先上升后下降,且当碳纳米管质量分数为1%时复合材料的力学性能最佳。碳纳米管在AlN-CNTs复合材料中的增韧机制主要是碳纳米管的拔出、碳纳米管的桥连和裂纹的偏转。

AlN-based composites containing different content of multi-wall carbon nanotubes(CNTs)as toughening material and certain content of calcium oxide(CaO)and yttrium oxide(Y2O3)as sintering aids were fabricated by hot-pressing method.CNTs were suffered from acid treatment and then mixed uniformly with AlN powders,Y2O3 and CaO by mechanical milling before hot-pressed sintering.Phase structures and morphologies of AlN-CNTs composites were characterized by X-ray diffraction(XRD)and scanning electron microscope(SEM),respectively.Physical and mechanical properties of AlN-CNTs composites were detected and analyzed.Results demonstrate that the mechanical properties of AlN-CNTs composites increase continuously with the increasing sintering temperature.Under the sintering temperature of 1750℃,the flexural strength and fracture toughness of AlN-CNTs composites firstly increases and then decreases as the CNTs content increases,and AlN-1wt%CNTs composites show the highest flexural strength and fracture toughness.The toughening mechanisms of CNTs in AlN-CNTs composites are CNTs pullout of the AlN matrix,CNTs bridging and crack deflection.