放电等离子烧结石墨烯增韧氧化锆陶瓷基复合材料力学性能研究-机械工程专业论文.docx

PAGE PAGE IV 放电等离子烧结石墨烯增韧氧化锆陶瓷基复合材料力学性能研究 5.6MPa m0.5).。 研究发现 GNS/TZP 复合材料主要增韧机制是石墨烯的拔出，桥接， 裂纹的偏转和裂纹的分叉。采用已有模型计算了复合材料界面在应力，并得出了 GNS 的临界增韧长度。计算了 GNS 的拔出应力释放率和复合材料的残余热应力，结果表 明残余热应力对于复合材料的力学性能影响可以忽略。仪器化划入测试结果表明，尽 管 GNS/TZP 复合材料的摩擦系数高于 TZP，但纯 TZP 材料在仪器化划入过程中的 损伤机制主要表现为脆性断裂，而 GNS/TZP 复合材料则转变为粘着磨损为主、脆性 断裂为辅的损伤机制，这主要源于 GNS/TZP 复合材料断裂韧性的显著改善。 关键词：石墨烯；氧化锆；力学性能；增韧。 作 者： 苏佳楠 指导老师： 陈 瑶 The mechanical properties of graphene nanoplatelets reinforced zirconia composite The mechanical properties of graphene nanoplatelets reinforced zirconia composite Abstract Zirconia ceramic material possesses very excellent chemical and physical properties. It has good physical and mechanical properties at room temperature, and also because of its high temperature resistance, good chemical resistance, it usually served in harsh environments and load conditions, so it is a very promising high-temperature ceramics. However, its intrinsic brittleness of ceramic and poor tribological properties, greatly limit it’s the wider applications. To achieve high mechanical performances, much effort has been devoted to develop zirconia ceramic-based composites , in whch ZrO2 matrix is toughened with high strength fibers, whiskers, hard particles and carbon nanotubes (CNTs). Graphene nanosheets (GNSs) are composed of a few graphene layers held together through weak van der Waals force, and they display compatible properties similar to that of monolayer graphene (e.g. tensile strength 130 GPa and Young’s modulus 0.5-1 TPa) , and GNSs are expected to be used as nanofillers in ceramics to produce composites with improved fracture toughness. Therefore, fabrication of the GNS reinforced 5 mol.% yttria stabilized tetragonal zirconia polycrystals (TZP) composites using spark plasma spray sintering (SPS) was proposed in this research, and the microstructure characteristics and the mechanical properties such as elastic modulus, hardness and fracture toughness of sintered composites were analyzed. Ultrasonic dis