Development of Corrosion Fatigue Testing Machine for Micro-Sized Specimens for Bio-MEMS

微电子机械系统(MEMS)设备有望作为生物MEMS(诊断和治疗设备)用于人体，并作为检测设备用于腐蚀环境。在这种MEMS器件中使用的组件的尺寸被认为是微米量级的。这一尺寸小于传统金属和合金中的晶粒度。这种微细材料的力学性能被认为不同于大块材料的力学性能。此外，由于微尺寸试件的比表面积比大块试件的比表面积大，因此认为腐蚀的影响更为突出。在MEMS器件中可能存在尺寸也在微米量级的缝隙，因此缝隙腐蚀也很重要。因此，微细材料的腐蚀疲劳性能对于设计腐蚀环境下的MEMS器件和微机械是非常重要的。然而，很少有研究对…进行研究微细材料具有更强的腐蚀疲劳性能。然而，在微小尺寸的试件上进行腐蚀疲劳试验存在一些困难。还有必要澄清该方法存在的问题，并找到解决办法。本文研制了一台微型疲劳试验机，并对微型Ni-P非晶态合金和304奥氏体不锈钢在空气和0.9%氯化钠溶液中进行了腐蚀疲劳试验，研究了尺寸效应对腐蚀疲劳性能的影响。利用聚焦离子束加工技术，以Ni-P非晶态合金薄膜和304奥氏体不锈钢薄板为原料，制备了尺寸为10微米×10微米×50微米的悬臂梁式试件。在空气中的疲劳寿命在100,000次以上，而在腐蚀环境中的疲劳寿命不到10,000次。在疲劳性能上观察到明显的环境效应。文中还讨论了该检测方法存在的几个问题及解决办法。较少

MEMS (Micro electro mechanical systems) devices are expected to be used in human body as Bio-MEMS (diagnosis and treatment devices) and in corrosive environments as inspection devices. The size of components used in such MEMS devices are considered to be in the order of microns. This size is smaller than the grain diameter in conventional metals and alloys. Mechanical properties of such micro-sized materials are considered to be different from those of bulk materials. In addition, the effect of corrosion is considered to be more prominent, because the specific surface area of micro-sized specimens is larger compared with that of bulk specimens. Crevices, the size of which is also in the order of microns, may exist in MEMS devices and thus crevice corrosion is also important. Therefore, corrosion fatigue properties of micro-sized materials are extremely important to design MEMS devices and micro-machines used in corrosive environments. However, there have been few studies that investiga … More te corrosion fatigue properties of micro-sized materials. However, there are several difficulties in corrosion fatigue tests on micro-sized specimens. It is also necessary to clarify the problems for the method and to find their solutions. In this investigation, we have developed a fatigue testing machine for micro-sized specimens, and corrosion fatigue tests for micro-sized Ni-P amorphous alloy and 304 austenitic stainless steel specimens have been carried out in air and 0.9% NaCl solution to investigate the size effects on corrosion fatigue properties. Specimens of cantilever-beam-type with dimensions of 10 microns × 10 microns × 50 microns were prepared from a Ni-P amorphous alloy thin film and a 304 austenitic stainless steel thin sheet by focused ion beam machining. The fatigue life of the specimen tested in air was more than 100,000 cycles, while that tested in the corrosive environment was less than 10,000 cycles. Distinct environmental effects on fatigue properties were observed. Several problems and solutions for the testing method were also discussed. Less