【作者】 王兴海；

【导师】 许崇海；

【作者基本信息】 山东轻工业学院 ， 材料学， 2011， 硕士

【摘要】 目前,模具是现代工业生产中不可缺少的重要装备,但模具工作条件较为恶劣,如冷挤压时的单位挤压力可达2000MPa以上,伴随模具内流动的金属与模具表面的剧烈摩擦以致模具温度随之升高,所以常常发生模具氧化、粘模或焊合等现象,加剧了模具的磨损,并降低了模具寿命。因此,选择高耐磨性、高硬度的模具材料已经成为提高模具寿命的一个重要途径。本文从提高金属陶瓷模具材料的综合力学性能出发,采用热压烧结方法制备出较高综合力学性能的Ti（C,N）基纳米复合金属陶瓷模具材料,对材料组分、微观结构、烧结工艺及其与材料综合力学性能之间的关系进行了研究。分析了Ti（C,N）基纳米复合金属陶瓷模具材料的增韧补强机理,并对Ti（C,N）基纳米复合金属陶瓷模具材料的摩擦磨损特性进行了研究。实验研究了纳米ZrO₂、微米WC对Ti（C,N）基纳米复合金属陶瓷模具材料力学性能和微观结构的影响,并对Ti（C,N）基纳米复合金属陶瓷模具材料的热压烧结工艺进行了优化,最终制备了综合力学性能较好的Ti（C,N）基纳米复合金属陶瓷模具材料,其抗弯强度为1144MPa、断裂韧性为8.60MPa·m^1/2、硬度为14.57GPa,与Ti（C,N）基金属陶瓷模具材料相比,虽然硬度降低,但是抗弯强度和断裂韧性分别提高了16.73%和40.07%。所制备的Ti（C,N）基纳米复合金属陶瓷模具材料中,纳米ZrO₂粉体的添加,细化了Ti（C,N）基金属陶瓷模具材料的晶粒,与Ti（C,N）基体形成了“晶内/晶间混合型”结构,形成了穿晶断裂/沿晶断裂混合断裂模式。此外,在纳米ZrO₂的相变增韧、裂纹的桥联、裂纹的偏转及分支等各种增韧补强机理的协同作用下Ti（C,N）基纳米复合金属陶瓷模具材料的综合力学性能得到了提高。对所制备的Ti（C,N）基纳米复合金属陶瓷模具材料进行了摩擦磨损性能实验研究,并借助扫描电子显微镜和X射线衍射仪对磨损试样表面进行了微观结构形貌观察与分析,研究了Ti（C,N）基纳米复合金属陶瓷模具材料的磨损机理,其磨损机理主要为磨粒磨损、氧化磨损和粘着磨损,而Ti（C,N）基金属陶瓷模具材料的磨损机理为晶粒的剥落和脆性断裂。最后进行初步的模具制造工艺验证。更多还原

【Abstract】 Recently, die is one of the important equipments needed in modern industry. But the working condition of die is extremely harsh, for instance the unit extrusion pressure of cold extrusion is up to 2000MPa. So some phenomena often happen such as soldering, oxidation and even welding in the extrusion process, leading to the intensifying of wear and reduction of service life because of the friction between die and workpiece. Therefore, the major way of improving die service life is to select the materials with better wear resistance and higher hardness. From the performance requirement of cermet die materials, a new Ti（C,N）-based nano-composite cermet die material with better comprehensive mechanical properties was prepared by hot pressing technique under vacuum atmosphere. The correlations among the material composion, the microstrures, the hot pressing process technique and comprehensive mechanical properties were investigated. Then, the strengthening and toughening mechanism of the Ti（C,N）-based nano-composite cermets die material has been systematically investigated. Meanwhile, the friction and wear behaviors of the Ti（C,N）-based nano-composite cermets die material has been studied in detail.The influence of nano-ZrO₂ and micro-WC on the microstructure and mechanical properties of Ti（C,N）-based nano-composite cermets die material has been discussed, then the hot press sintering was optimized. Ti（C,N）-based nano-composite cermets die material were fabricated successfully with better comprehensive mechanical properties. Its flexural strength, fracture toughness and hardness is 1144MPa, 8.60MPa·m^1/2 and 14.57GPa, respectively. Although the hardness is slightly decreased, the flexural strength and fracture toughness is nearly 16.73% and 40.07% higher than that of the cermet without any addition of nano-ZrO₂ and micro-WC. It is found that grain-refining trend and inter/trans mixed fracture mode happens with adidtion of nano-ZrO₂. Morever, some strengthening and toughening mechanisms, such as crack bridging, crack deflection and branching has improved the comprehensive mechanical properties of Ti（C,N）-based nano-composite cermet die material.The friction and wear mechanisms of Ti（C,N）-based nano-composite cermets Die Material were investgated by the scanning electron microscopy and X-ray diffraction on the wearing sample of Ti（C,N）-based nano-composite cermets die material.Meanwhile, the friction and wear behaviors of the Ti（C,N）-based nano-composite cermets die material has been studied, its dominant wear mechanisms are abrasive wear, oxidative wear and adhesive wear, while the dominant wear mechanisms of Ti（C,N）-based cermet die material are grain stripping and brittle fracture. At last, a primary process validation of die manufacture was done.更多还原