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Zhu Z.,Huazhong University of Science and Technology | Yi C.,Huazhong University of Science and Technology | Shi T.,Huazhong University of Science and Technology | Gao Y.,Jiangxi Province Key Laboratory of Numerical Control Technology and Application | And 2 more authors.
Advances in Mechanical Engineering | Year: 2014

A suction casting process for fabricating Zr55Cu30Al10Ni5 bulk metallic glass microcomponent using silicon micromold has been studied. A complicated BMG microgear with 50 m in module has been cast successfully. Observed by scanning electron microscopy and laser scanning confocal microscopy, we find that the cast microgear duplicates the silicon micromold including the microstructure on the surface. The amorphous state of the microgear is confirmed by transmission election microscopy. The nanoindentation hardness and elasticity modulus of the microgear reach 6.5 GPa and 94.5 GPa. The simulation and experimental results prove that the suction casting process with the silicon micromold is a promising one-step method to fabricate bulk metallic glass microcomponents with high performance for applications in microelectromechanical system. © 2014 Zhijing Zhu et al.


Zhu Z.,Huazhong University of Science and Technology | Yi C.,Huazhong University of Science and Technology | Shi T.,Huazhong University of Science and Technology | Zhang Y.,Huazhong University of Science and Technology | And 2 more authors.
Advances in Materials Science and Engineering | Year: 2015

We demonstrated hot embossing of Zr65Cu17.5Ni10Al7.5 bulk metallic glass micropart using stacked silicon dies. Finite element simulation was carried out, suggesting that it could reduce the stress below 400 MPa in the silicon dies and enhance the durability of the brittle silicon dies when using varying load mode (100 N for 60 s and then 400 N for 60 s) compared with using constant load mode (200 N for 120 s). A micropart with good appearance was fabricated under the varying load, and no silicon die failure was observed, in agreement with the simulation. The amorphous state of the micropart was confirmed by differential scanning calorimeter and X-ray diffraction, and the nanohardness and Young's modulus were validated close to those of the as-cast BMG rods by nanoindentation tests. The results proved that it was feasible to adopt the varying load mode to fabricate three-dimensional Zr-based bulk metallic glass microparts by hot embossing process. Copyright © 2015 Zhijing Zhu et al.


Gao Y.,Jiangxi Province Key Laboratory of Numerical Control Technology and Application | Peng Z.,Intel Corporation | Shi T.,Huazhong University of Science and Technology | Tan X.,Huazhong University of Science and Technology | And 4 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2015

In this paper, we developed a top-down method to fabricate complex three dimensional silicon structure, which was inspired by the hierarchical micro/nanostructure of the Morpho butterfly scales. The fabrication procedure includes photolithography, metal masking, and both dry and wet etching techniques. First, microscale photoresist grating pattern was formed on the silicon (111) wafer. Trenches with controllable rippled structures on the sidewalls were etched by inductively coupled plasma reactive ion etching Bosch process. Then, Cr film was angled deposited on the bottom of the ripples by electron beam evaporation, followed by anisotropic wet etching of the silicon. The simple fabrication method results in large scale hierarchical structure on a silicon wafer. The fabricated Si structure has multiple layers with uniform thickness of hundreds nanometers. We conducted both light reflection and heat transfer experiments on this structure. They exhibited excellent antireflection performance for polarized ultraviolet, visible and near infrared wavelengths. And the heat flux of the structure was significantly enhanced. As such, we believe that these bio-inspired hierarchical silicon structure will have promising applications in photovoltaics, sensor technology and photonic crystal devices. Copyright © 2015 American Scientific Publishers All rights reserved.

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