【作者】 衣明东；

【导师】 许崇海；

【作者基本信息】 山东轻工业学院 ， 材料学， 2010， 硕士

【摘要】 本文针对现有陶瓷模具材料应用中所反映出的强度与韧性不足以及使用性能有待改善等问题,综合考虑模具材料、工件材料、工艺条件等影响因素,进行陶瓷模具摩擦学设计。另外提出从材料研制角度并行进行摩擦学设计、变被动设计为主动设计的设想,在设计阶段重点研究可以加强材料耐磨性的组分。在此基础上,将其应用到材料研发过程,采用热压烧结工艺制备一种新型氧化锆纳米复合陶瓷模具材料,并研究其制备工艺、微观结构、力学性能与摩擦磨损性能。系统探讨了不同组分含量与粒径、烧结工艺对氧化锆纳米复合陶瓷模具材料力学性能和微观结构的影响,研制成功了具有良好综合力学性能的ZrO2-TiB2-Al2O3纳米复合陶瓷模具材料。在烧结温度1430℃、保温时间60℃/min和压力35MPa条件下复合陶瓷材料的抗弯强度达到1055MPa、断裂韧性为10.57MPa·m1/2、硬度为13.59GPa,与单相氧化锆陶瓷材料相比,其抗弯强度和断裂韧性都得到了大幅度提高。在所制备的氧化锆纳米复合陶瓷模具材料中,优化后的烧结工艺可以将四方相氧化锆几乎全部稳定到室温状态,提高了氧化锆的相变增韧作用;微米TiB2和Al2O3的加入对基体材料起到较强的颗粒增强作用,与纳米ZrO2形成典型的晶内/晶间混合型结构,断裂模式变为沿晶/穿晶混合型断裂模式;另外,包括裂纹偏转、裂纹桥联、裂纹分支和颗粒拔出等各种增韧补强机理的协同作用,使氧化锆纳米复合陶瓷模具材料的综合力学性能得到了较大提高。对所制备的氧化锆纳米复合陶瓷模具材料进行了摩擦磨损性能实验研究,采用环境扫描电镜观察磨损表面的微观形貌,并对磨损表面的元素和物相变化进行了电子能谱和X射线衍射分析,研究了ZrO2-TiB2-Al2O3纳米复合陶瓷模具材料的磨损机理。研究表明,组分变化引起的力学性能和微观结构的变化是摩擦磨损性能变化的主要原因;氧化锆纳米复合陶瓷模具材料的摩擦系数随摩擦时间先升高后降低并在某一范围内上下波动,磨损率随磨损时间的延长逐渐降低;氧化锆纳米复合陶瓷模具材料的摩擦系数与磨损率都表现为高速摩擦下小而低速下较大,载荷的过高和过低都会导致磨损率的上升。氧化锆纳米复合陶瓷模具材料的主要磨损机理为机械冷焊和粘着磨损。更多还原

【Abstract】 From the problems in the application of the existing ceramic die materials such as poor flexural strength, fracture toughness and operational performance, tribological design of the ceramic die is carries out by overall evaluation factors such as die materials, work piece materials, and technological conditions to reduce the friction coefficient and wear rate. Tribological design is carried in parallel with the material development, changes the passive design for the initiative design and reinforcement the wear resistant component in the material design. Then, a new nanocomposite ceramic die material was prepared by vacuum hot pressing technique with the application of the material research and development process, and the processing techniques, microstructure, mechanical properties and the friction and wear behavior was studied.The effect of different particle size and content of component powders on the microstructure and mechanical properties of ZrO2-TiB2-Al2O3 nanocomposite ceramic die material is investigated systemically, ZrO2-TiB2-Al2O3 nanocomposite ceramic die material with good mechanical properties was fabricated successfully. The highest flexural strength, fracture toughness and hardness of ZrO2-TiB2-Al2O3 nanocomposite ceramic die material reaches 1055MPa, 10.57MPa·m1/2and 13.59GPa, respectively by means of the vacuum hot pressing technique at 1430℃for 60min at 35MPa. Compared to the single-phase ZrO2 ceramic materials, the flexural strength and fracture toughness has been improved greatly. In the ZrO2 nanocomposite ceramic die materials, the optimum sinter process could nearly completely stabilize the t-ZrO2 to the room temperature condition that can enhance the toughening effect of ZrO2. The particle toughening effect can be achieved by the addition of the micrometer TiB2 and Al2O3 powders, and the typical mixed granular fracture modes were happened. Besides, crack deflection, crack bridging, crack branching and particle pull-out are the significant strengthening and toughening mechanisms. As a result, the comprehensive mechanical properties of ZrO2 nanocomposite ceramic die materials have been greatly enhanced.The wear morphology of ZrO2 nanocomposite ceramic die materials were studied using a environment scanning electron microscopy (ESEM), and the element and the ______________________ phase composition were analyzed by energy dispersive analysis spectroscopy (EDAS) and X-ray diffraction (XRD). The friction and wear mechanisms of ZrO2 nanocomposite ceramic die materials were studied. It is indicated that the major cause of the friction and wear behavior is attributied to the changes of the microstructure and the mechanical properties by the component change. The friction coefficient of the ZrO2 nanocomposite ceramic die materials is first increased and then decreased, and reached a relative steady value. The wear rate reduces gradually along with the attrition time. The friction coefficient and wear rate of the ZrO2 nanocomposite ceramic die materials decreases with the increases of the rotational speed,and the over-high or over-low normal load is bad for the wear rate. While the dominant wear mechanisms of ZrO2 nanocomposite ceramic die materials are mechanical interlocking and adhesive wear.更多还原