Development of Mechanical Testing Machine for Microelements

研制了一台专门设计的试验机（载荷范围：0.1mN -5 N，精度：小于0.02 μ N，施加位移范围：0 - 250 μ m），可以进行包括微元件疲劳在内的力学测试。通过电磁致动器将载荷施加到试样上，并使用差动Transformer（测量精度：0.1 μ m）测量位移。因此，可以以足够的精度进行微型元件和纤维增强材料的机械测试。通过使用该开发的机器，准静态弯曲试验的单晶硅微元件制造的划片和光刻和横向压缩和纵向拉伸试验的各种类型的纤维增强体，包括芳纶纤维和陶瓷纤维进行。单晶硅微元件发生弹性变形直至最终发生灾难性破坏，表现出脆性性质，其弹性模量与晶体取向有关。研究了制备工艺和试样尺寸对断裂强度的影响，讨论了影响断裂强度的主要因素。在纤维增强材料的力学性能试验中，研究了真空和潮湿环境对纤维增强材料断裂强度的影响。无论是芳纶纤维还是Al_2O_3、SiC和Si-C-Ti-O陶瓷纤维，其拉伸强度都因环境中水分的存在或吸水而降低。

A specially designed testing machine (load range : 0.1mN - 5N, accuracy : less than 0.02muN, applied displacement range : 0 - 250mum) was developed, which enables mechanical testing including fatigue of microelements. Loads were applied to a specimen by means of an electromagnetic actuator, and the displacement was measured with a differential transformer (measuring accuracy : 0.1mum). Mechanical testing of microelements and fiber reinforcements could thereby be performed with a sufficient precision. By using this developed machine, quasi-static bending tests of single-crystalline silicon microelements fabricated by dicing and photoetching and lateral compression and longitudinal tensile tests of various types of fiber reinforcements including aramid fibers and ceramic fibers were performed. Single-crystalline silicon microelements deformed elastically until final catastrophic failure, showing a brittle nature, and the elastic modulus was dependent on crystal orientation. The influences of the fabrication process and specimen size on the fracture strength were investigated, and the dominating factor on the strength was discussed. In the case of mechanical tests of fiber reinforcements, the influence of environments including vacuum and humidified environments on the fracture strength were investigated. For both aramid fibers and ceramic fibers of Al_2O_3, SiC and Si-C-Ti-O, tensile strength decreased by existence of water in the environment or water absorption.