微米级金属玻璃模具结构强度及疲劳性能

发布时间：2018-01-17 14:44

本文关键词：微米级金属玻璃模具结构强度及疲劳性能　出处：《郑州大学》2017年硕士论文　论文类型：学位论文

【摘要】：近些年来,微机电系统(MEMS)领域得到了快速发展,在对结构件精度提出更高要求的基础上,精密微模具的加工成为了关键的问题。现有的微模具加工方法均存在一定局限性。寻找一种成本低的加工方法制作出强度高、精度高的微模具具有十分重要的工程意义。金属玻璃,不仅具有优异的强度、硬度、耐磨损等力学性能,当温度升高至其过冷液相区时,又可以像高分子材料一样成型各种复杂的图形。由于缺少了传统晶态金属内部晶界结构特点的限制,对金属玻璃进行微热压印成型实验,可以在原子级别上精确复制模具上的结构化图案。降低温度,金属玻璃既可以保持这些被复制上的图案,又可以恢复原有优异的力学、物理以及化学性能。大部分金属玻璃的玻璃化转变温度都高于常用工程高分子材料的熔融温度,这使得金属玻璃可以作为模具应用于微成形领域。本文主要针对微米级金属玻璃模具结构强度及疲劳性能,开展以下几方面研究:(1)对Zr41.2Ti13.8Cu12.5Ni10Be22.5(Vitreloy1,简称Vit-1)大块金属玻璃进行切割,制备出不同尺寸的块状金属玻璃样品。利用自行设计的抛光装置抛光圆片状样品。通过原子力显微镜对抛光后的样品表面进行粗糙度测定。X射线衍射验证切割抛光后的金属玻璃样品仍然处于非晶状态。利用DSC测定出该金属玻璃的玻璃化转变温度及过冷液相区,为后续热压实验温度的设定提供参考。利用ICP体硅加工工艺,获得表面具有特定微结构的硅模具。对圆片状金属玻璃样品进行微热压印成型实验,获得单轴静态压缩和压-压疲劳实验所需微圆柱样品,通过扫描电子显微镜和激光共聚焦显微镜对微圆柱形貌进行表征。(2)取一部分微圆柱样品进行退火处理。利用X射线衍射对退火前后的样品进行表征,并进行单轴静态压缩实验,比较微圆柱样品退火前后的力学性能。利用扫描电子显微镜对静态压缩失效的样品进行形貌表征并分析其静态压缩断裂失效机理。(3)利用疲劳试验机分别对退火前后的微圆柱样品进行单轴压-压疲劳实验。取107次循环寿命为无限寿命。将实验获得的应力-寿命数据点拟合得到S-N曲线,比较退火前后样品的压-压疲劳性能。通过扫描电子显微镜对失效样品的整体及断裂表面形貌进行观测,并分析样品在循环载荷作用下失效的机理。(4)利用抛光机对不同尺寸的大块金属玻璃板材进行金相抛光,通过微热压印成型实验复制硅模具上不同形状的微流控芯片图形。在得到的金属玻璃微模具上利用热压成型工艺加工PMMA微流控芯片成品。再利用有限元模拟软件COMSOL,以实验获得的疲劳寿命S-N曲线作为失效判据,预测微模具结晶前后在高分子材料热压成型过程中的使用寿命。并对金属玻璃微模具在金属板材冷压过程中的应用进行展望,预测其结构强度及疲劳寿命。
[Abstract]:In recent years, the field of MEMS / MEMS) has been developed rapidly, on the basis of higher requirements for the accuracy of structural parts. The machining of precision micromold has become a key problem. The existing micromold processing methods have some limitations. To find a low-cost processing method to make high strength. Metal glass not only has excellent mechanical properties, such as strength, hardness, wear resistance and so on, when the temperature rises to its supercooled liquid region. Because of the lack of traditional crystalline metal internal grain boundary structure characteristics, metal glass microthermal imprinting molding experiment was carried out. At the atomic level, the structural patterns on the mould can be accurately copied. By lowering the temperature, the metallic glass can not only keep the duplicated patterns, but also restore the original excellent mechanics. Physical and chemical properties. The glass transition temperature of most metallic glasses is higher than the melting temperature of common engineering polymer materials. This makes metal glass can be used in the field of microforming. This paper mainly focuses on the structural strength and fatigue properties of micrometer metal glass dies. The following studies were carried out on Zr41.2Ti13.8Cu12.5Ni10Be22.5(Vitreloy1. Vit-1) large pieces of metallic glass are cut. Bulk metallic glass samples of different sizes were prepared. The wafer samples were polished with a self-designed polishing device. The surface roughness of polished samples was determined by atomic force microscope. X-ray diffraction was used to verify the cutting. The glass transition temperature and supercooled liquid region of the metallic glass were determined by DSC. By using the ICP bulk silicon processing technology, the silicon mold with specific microstructures on the surface was obtained. The microthermal imprinting experiments were carried out on the wafer metal glass samples. The microcylindrical samples for uniaxial static compression and compression compression fatigue tests were obtained. Scanning electron microscope (SEM) and laser confocal microscope (LSCM) were used to characterize the microcylinder shape. Some of the microcylindrical samples were annealed. X-ray diffraction was used to characterize the samples before and after annealing. The uniaxial static compression experiment was carried out. The mechanical properties of microcylindrical samples before and after annealing were compared. The morphology of static compression failure samples was characterized by scanning electron microscope (SEM) and the failure mechanism of static compression fracture was analyzed. The fatigue tests of microcylinder samples before and after annealing were carried out by using a fatigue tester. The life of 107 cycles was taken as infinite life. The S-N curve was obtained by fitting the stress-life data points obtained from the experiment. . The compressive and compressive fatigue properties of the samples before and after annealing were compared. The morphology of the failure samples and the fracture surface were observed by scanning electron microscope (SEM). The failure mechanism of the sample under cyclic loading is analyzed. (4) A polishing machine is used to finish the large metal glass plate with different sizes. The microfluidic chip graphics of different shapes on silicon die were reproduced by microthermal imprinting experiment. The finished products of PMMA microfluidic chip were processed by hot pressing process on the obtained metal glass micromold. Then the finite element model was used to process the finished product of PMMA microfluidic chip. Quasi software COMSOL. The fatigue life S-N curve obtained by experiment is used as the failure criterion. The service life of micromould in the process of hot pressing of polymer material was predicted before and after crystallization, and the application of metal glass micromould in cold pressing process of metal sheet was forecasted, and the structural strength and fatigue life were forecasted.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG139.8;TG76

【相似文献】