碳纳米管-ZrB_2-SiC陶瓷基复合材料的制备与性能研究

Preparation and Properties of ZrB_2-SiC Ceramic Composites Reinforced by Carbon Nanotubes

研究了用热压烧结方法制备的不同碳纳米管(CNTs)含量的ZrB_2-SiC-xwt%CNTs(x=0、1.0、2.5、4.0)复合材料的工艺条件、力学性能和微观结构.用TEM观察了试样的微观结构,用SEM观察了试样断口形貌和裂纹扩展情况,并对其强韧化机制进行了分析.研究表明,碳纳米管主要分布沉积在ZrB_2颗粒内部,形成内晶型结构,在CNTs含量为2.5%时,相对密度、维氏硬度和弯曲强度分别为99.6%、21.7GPa和542MPa,断裂韧性达到6.10MPa·m^(1/2).碳纳米管加入后材料致密性提高、晶粒细化,所形成的内晶型结构是材料强度和韧性得以提高的原因.

ZrB2-SiC-xwt% carbon nanotubes （x=0, 1.0, 2.5, 4.0） ceramic composites were fabricated by the hot-pressing sintering. The prepared conditions, mechanical properties and microstructure were also investigated. TEM was used to observe the microstructure and SEM was used to analyze the fracture surface and crack propagation. Then, the strengthening and toughening mechanism of carbon nanotubes were discussed. Results show that carbon nanotubes can deposit in the ZrB2 crystal grain and form intragranular structure. When the carbon nanotubes content is 2.5wt%, the flexural strength and toughness reach 542MPa and 6.10MPa.m^1/2 respectively, with the relative density of 99.6% and Vickers hardness value of 21.7GPa. The reasons of the mechanical properties improvement are the increased compactness, grain refining and the intragranular structure caused by the introduction of carbon nanotubes.