【作者】 孝煦；

【导师】 许崇海；

【作者基本信息】 山东轻工业学院 ， 机械电子工程， 2009， 硕士

【摘要】 氧化铝陶瓷具有高硬度、耐磨损、耐高温、抗腐蚀、低密度、原料分布广等优点,但韧性和强度较差,限制了其广泛应用。寻求合适的方法提高氧化铝陶瓷的强韧性,具有重要的理论意义和应用价值。本文用纳米ZrO₂与Ti（C,N）多相复合协同强韧化Al₂O₃陶瓷,研制成功了纳米复合陶瓷工模具材料Al₂O₃/Ti（C,N）/ZrO₂,其抗弯强度为796 MPa、断裂韧性为8.92 MPa·m^1/2、硬度15.4GPa。探讨了组分含量、烧结工艺对纳米陶瓷工模具材料微观结构和力学性能的影响,与单一的Al₂O₃陶瓷材料相比,其抗弯强度和断裂韧性都得到大幅提高。在致密的烧结陶瓷中,纳米ZrO₂和Ti（C,N）与微米Al₂O₃形成了典型的晶内/晶间混合型结构,裂纹从晶间到晶内再到晶间的路径扩展,消耗了更多的断裂能,形成了沿晶/穿晶混合的断裂模式,是其综合力学性能得到较大提高的主要原因。裂纹偏转和桥联及裂纹分支和颗粒拔出,是复合材料韧性提高的表现。对纳米陶瓷工模具材料进行了摩擦磨损性能实验研究,其摩擦系数和摩擦率均明显低于单相Al₂O₃陶瓷。并对其磨损表面微观形貌进行了观察和分析,探讨了Al₂O₃/Ti（C,N）/ZrO₂纳米复合陶瓷工模具材料的磨损机理。单相Al₂O₃陶瓷的磨损机理为脆性断裂和磨粒磨损,Al₂O₃/Ti（C,N）/ZrO₂纳米陶瓷工模具材料的磨损机理为机械冷焊和磨粒磨损。分析了Al₂O₃/Ti（C,N）/ZrO₂纳米陶瓷刀具的磨损形貌和磨损机理,其主要磨损机理是磨粒磨损、粘结磨损。更多还原

【Abstract】 The alumina ceramic has excellent hardness, wear resistance, high-temperature wear resistance, corrosion resistance, low density and wide raw materials, but the low fracture toughness and low strength limit its wide application.Exploiting an effective approach to improve the mechanical properties of the alumina ceramic, especially its fracture toughness and flexural strength, will be significant for widening the actual application, as well as for the theoretical value.Nano-ZrO₂ and Ti（C,N） have been added in the study. Nanocomposite ceramic tool and die material of Al₂O₃/Ti（C,N）/ZrO₂ was fabricated successfully, its flexural strength, fracture toughness and Vickers hardness are 796 Mpa, 8.92 MPa-m^1/2 and 15.4 GPa respectively.The effects of constituent content and sintering technology on the microstructure and mechanical properties of nanocomposite ceramic tool and die materials were discussed. The flexural strength and fracture toughness are much higher than that of pure Al₂O₃ ceramic material. The nano-scale ZrO₂ and Ti（C,N） particles are located between or within Al₂O₃ matrix. Thus the typical mixture crystal microstructure is formed in the dense compacts, which resulted in the mixture granular fracture modes. The zigzag crack path, which is from the grain boundary into the grain and then turning to the boundary, can result in higher consumption of fracture energy and the increase of fracture toughness. Crack deflection, crack bridging, crack branching and grain pull-out reveals the improvement of the fracture toughness of the composites.The wear mechanism of nanocomposite ceramic tool and die materials were discussed by analyzing SEM micrographs of wear tracks on typical specimens. The friction coefficient and wear rate of Al₂O₃/Ti（C,N）/ZrO₂ nanocomposite ceramic tool and die materials are obviously lower than that of the monolithic Al₂O₃. The dominant wear mechanisms of pure Al₂O₃ may be brittle fracture and abrasive wear. While the dominant wear mechanisms of Al₂O₃/Ti（C,N）/ZrO₂ nanocomposite ceramic tool and die materials may be mechanical interlocking and abrasive wear. The wear pattern and mechanisms of Al₂O₃/Ti（C,N）/ZrO₂ nanocomposite ceramic tool and die materials were analyzed. The main wear mechanisms are abrasive and adhesion.更多还原