Single-mode fluorotellurite glass fiber

By multi-stage rod-in-tube fiber drawing process, a single-mode fluorotellurite glass fiber was fabricated and reported for the first time. Benefiting from chemical–physical dehydration process to remove water and OH⁻ groups, the propagation loss was decreased to 1.9 dB/m at 1550 nm and the infrared window is extended from 2.8 μm to 4.2 μm, i.e. a new kind of mid-infrared glass fiber. The fiber is with a small core of 3.52 μm in diameter to meet single-mode condition, and the effective nonlinear parameter γ was estimated to be 236.7 W⁻¹ km⁻¹ at 1550 nm by using continuous-wave self-phase modulation method. © 2015 Elsevier B.V. All rights reserved.     

生物质基碳气凝胶制备及应用研究

生物质材料成本低廉、碳源丰富,是碳气凝胶制备中最经济、环保和可持续性的原料。生物质基碳气凝胶展现出密度低、弹性高、比表面积大和导电性好等优异特性,有望广泛应用于电化学储能器件和吸附净化等领域。综述了生物质基碳气凝胶,如纤维素碳气凝胶、木质素基碳气凝胶、生物质衍生物基碳气凝胶以及碳气凝胶复合结构材料的制备工艺,总结了生物质基碳气凝胶在吸附和电化学等领域的应用研究。最后,分析了大规模制备结构均一和性能优良的生物质基碳气凝胶面临的机遇与挑战。     

Experimental investigation on carbon steel micro-rod machining by LS-WEDT

This article proposed for the first time the method of the low-speed wire electrical discharge turning (LS-WEDT) combined with the multiple cutting strategy to fabricate carbon steel micro-rods. First, the rotating apparatus submerged in working fluid is designed and manufactured to enable the low-speed wire electrical discharge machine to generate cylindrical geometries. Besides, material removal rate, surface roughness, and machining precision of the micro-rod manufactured by the LS-WEDT are, respectively, investigated. Moreover, the surface microstructure and surface chemical reaction of micro-rods are characterized using scanning electron microscopy and energy-dispersive spectroscopy analysis. Experimental results display that the micro-rod of 70?µm diameter and 1000?µm length can be successfully fabricated. More importantly, the mean absolute diameter deviation of the micro-rod fabricated by LS-WEDT is 0.65?µm and the surface roughness is 0.53?µm, which identified the high machining precision and good surface quality of the micro-rod.     

Selective Nanoscale Fabrication with Roughness Reduction of Polycrystalline Silicon by Physically Induced Fluorine Bonds Using Atomic Force Microscope

Polycrystalline silicon (poly-Si) is widely used as a gate layer in integrated circuits, transistors, and channels through nanofabrication. Nanoremoval and roughness control are required for nanomanufacturing of various electronic devices. Herein, a nanoscale removal method is developed to overcome the limitations of microcracks, complex procedures, and time-consuming conventional fabrication and lithography methods. The method is implemented with a mechanically induced poly-Si phase transition using atomic force microscope (AFM). Mechanical force induces the covalent bonds between silicon and fluorine atoms which cause the phase transition of poly-Si. Then, the bond structure of the Si molecules is weakened and selectively removed by nano-Newton-scale force using AFM. A selective nanoscale removal with roughness control is implemented in 0.5 mM TBAF solution after mechanical force (43.58–58.21 nN) is applied. By the magnitude of nano-Newton force, the removal depth of poly-Si is controlled from 2.66 to 21.52 nm. Finally, the nanoscale fabrication on poly-Si wafer is achieved. The proposed nanoremoval mechanism is a simple fabrication method that provides selective, nanoscale, and highly efficient removal with roughness control.     

Advances in the fabrication of titanium based composites

Titanium alloy metal matrix composites reinforced with silicon carbide fibre are being evaluated for a range of highly loaded aerospace applications. Although expensive, if used selectively they can have a dramatic effect on performance and weight. The SMC has one of the strongest capabilities in Europe for the development and production of titanium fibre reinforced MMCs. Consisting of the DRA Sigma silicon carbide fibre manufacturing facility, producing fibre on a commercial basis, and the manufacture of titanium alloy MMCs in commercial quantities by the foil fibre route, and at pilot scale using the alternative matrix coated fibre route. In the foil fibre route a filament winding and fugitive binder method is used to produce a range of component shapes with excellent fibre distribution and consistent properties. The matrix coated fibre process is seen to have advantages over the alternative methods and is likely to become an important manufacturing route for titanium MMCs, particularly for exotic high temperature titanium alloys and intermetallics, and for shapes such as rings, tubes and shafts. As no titanium MMCs components have yet reached full production, it is unclear which of these fabrication methods will become commercially viable, if any. But, the choice is likely to be based on cost, availability and product quality.     

晶圆制造物料运输系统实时调度方法

Interbay物料运输系统的运行效率对晶圆制造系统的影响较大。为减少运输小车平均搬运工件时间、晶圆工件的等待时间和运输小车的临时性堵塞,提出一种基于匈牙利算法的实时调度方法,并建立工件调度模型。基于300 mm晶圆制造系统数据的仿真结果表明,与传统的Interbay物料运输调度方法相比,该方法能有效提高Interbay物料运输系统的综合性能。     

Control of ignition delay in microfabricated hot-wire igniters: Simulation, fabrication, and experimental results

The presented work studied thermal interactions between laminated, metal-foil, hot-wire igniters and exothermic solid-state, composite chemical systems in order to demonstrate precise timing control of a thermal ignition process. The study includes FEA modeling, device fabrication, and characterization to demonstrate control microthruster ignition delays to within 2 ms. The modeling included studies of total ignition delay as well as the ignition delay variation versus process variations. Microthrusters were then fabricated via printed circuit board lamination, and the ignition performance was characterized. The characterization showed agreement with modeling to within 2-sigma for most cases. And the characterization demonstrated that the ignition delay could be controlled to within 0.36 and 0.84 ms for the best case. Furthermore, this performance was demonstrated with a small battery supply (200-600 mAh) and minimal electronics in the ignition system. This work extends the use of current microthrusters to short-lifetime applications that need high forces delivered in millisecond time intervals.     

A new DFM approach to combine machining and additive manufacturing

Design for manufacturing (DFM) approaches aim to integrate manufacturability aspects during the design stage. Most of DFM approaches usually consider only one manufacturing process, but product competitiveness may be improved by designing hybrid modular products, in which products are seen as 3-D puzzles with modules realized individually by the best manufacturing process and further gathered. A new DFM system is created in order to give quantitative information during the product design stage of which modules will benefit in being machined and which ones will advantageously be realized by an additive process (such as Selective Laser Sintering or laser deposition). A methodology for a manufacturability evaluation in case of a subtractive or an additive manufacturing process is developed and implemented in a CAD software. Tests are carried out on industrial products from automotive industry.     

基于神经网络的集成电路生产过程建模与优化

以提高半导体生产线的成品率为目标,利用神经网络对半导体芯片生产过程进行了建 模和优化.首先使用神经网络方法建立模型,确定生产线上工艺参数和成品率之间的映射关系, 构造多维映射函数曲面;随后对多维映射函数曲面进行搜索,搜索成品率最高的最优点,据此确 定工艺参数的规范值;最后,根据优化后的工艺参数规范进行实际生产.采用这种优化建议,半 导体生产线的平均成品率由51.7%提高到了57.5%.