Analysis of the current density characteristics in through-mask electrochemical micromachining (TMEMM) for fabrication of micro-hole arrays on invar alloy film

Invar alloy consisting of 64% iron and 36% nickel has been widely used for the production of shadow masks for organic light emitting diodes(OLEDs) because of its low thermal expansion coefficient(1.86 ? 10à6cm/°C).To fabricate micro-hole arrays on 30 lm invar alloy film,through-mask electrochemical micromachining(TMEMM) was developed and combined with a portion of the photolithography etching process.For precise hole shapes,patterned photoresist(PR) film was applied as an insulating mask.To investigate the relationship between the current density and the material removal rate,the principle of the electrochemical machining was studied with a focus on the equation.The finite element method(FEM) was used to verify the influence of each parameter on the current density on the invar alloy film surface.The parameters considered were the thickness of the PR mask,inter-electrode gap(IEG),and electrolyte concentration.Design of experiments(DOE) was used to figure out the contribution of each parameter.A simulation was conducted with varying parameters to figure out their relationships with the current density.Optimization was conducted to select the suitable conditions.An experiment was carried out to verify the simulation results.It was possible to fabricate micro-hole arrays on invar alloy film using TMEMM,which is a promising method that can be applied to fabrications of OLEDs shadow masks.     

基于墩头轮廓钛合金铆接夹具的优化设计

针对某型号机在弹塑性理论和逆向工程的基础上,采用普通铆接方式,通过计算和数值模拟对铆接的夹具进行优化设计。结果表明,此夹具的优化设计可使铆接后的干涉量均匀度大大提高,残余应力分布更合理且得出了铆接后干涉量检测的重要评估手段,为飞机制造过程中工艺的优化和装配效率的提高提供重要参考价值。     

Preparation of bimodal grain size 7075 aviation aluminum alloys and their corrosion properties

The bimodal grain size metals show improved strength and ductility compared to traditional metals; however, their corrosion properties are unknown. In order to evaluate the corrosion properties of these metals, the bimodal grain size 7075 aviation aluminum alloys containing different ratios of coarse(100 μm in diameter) and fine(10 μm in diameter) grains were prepared by spark plasma sintering(SPS). The effects of grain size as well as the mixture degree of coarse and fine grains on general corrosion were estimated by immersion tests, electrochemical measurements and complementary techniques such as scanning electron microscope(SEM) and transmission electron microscope-energy disperse spectroscopy(TEM-EDS). The results show that, compared to fine grains, the coarse grains have a faster dissolution rate in acidic NaCl solution due to the bigger size,higher alloying elements content and larger area fraction of second phases in them. In coarse grains,the hydrogen ions have a faster reduction rate on cathodic second phases, therefore promoting the corrosion propagation. The mixture of coarse and fine grains also increases the electrochemical heterogeneity of alloys in micro-scale, and thus the increased mixture degree of these grains in metal matrix accelerates the corrosion rate of alloys in acidic NaCl solution.     

激光熔化沉积TA15+Ti_2AlNb合金的组织与力学性能

将TA15和Ti_2AlNb合金粉末以不同比例预混,采用激光熔化沉积工艺,制备出40%TA15+60%Ti_2AlNb,50%TA15+50%Ti_2AlNb,60%TA15+40%Ti_2AlNb(质量分数)3种比例的合金薄壁,分析了薄壁的成分、组织及力学性能。结果表明:3种沉积薄壁的成分分布均匀,合金由α相、α2相及β/B2相组成,针状α相和α2相呈网篮状分布在初生β/B2晶粒内部;3种合金的抗拉强度分别为1108 MPa,1071 MPa,1105 MPa,断裂伸长率分别为3.0%,2.2%,3.8%;拉伸断口可见沿α2相撕裂产生的撕裂棱,断裂方式均为准解理断裂。     

高速永磁电机综合设计与分析

高速非晶合金永磁电机设计受电磁、机械、温升的制约,因此高速非晶合金永磁电机的设计是一个多物理场综合设计的过程。针对高速非晶合金永磁电机设计受多物理场制约的问题,基于多物理场的分析方法,分析了非晶合金材料对高速永磁电机电磁性能的影响；研究了内置式永磁转子在高速运行状态下的应力分布,并分析了轴承支撑刚度对转子系统临界转速的影响；针对高速非晶合金永磁电机损耗分布特点研究了其温度场的分布。基于提出的多物理场综合设计方法,设计并制造了一台额定功率15 kW、最高转速30 000 r/min的高速内置式非晶合金永磁电机,并对样机进行了试验,验证了仿真分析与设计方法的可行性,为高速非晶合金永磁电机的设计提供参考。     

钛合金蜂窝三层结构的扩散焊接研究

介绍了俄罗斯钛合金蜂窝三层结构扩散焊接的研究成果.详细介绍了铝合金、焊接规范选择、接头应力变形状态的分析、模拟计算等,有助于国内钛合金的焊接研究.     

基于响应曲面的时效成形材料参数修正

为了提高时效成形中回弹现象的有限元仿真精度,使用均匀试验设计结合响应曲面设计的方法,建立了仿真误差对于材料参数的响应函数,求解出材料参数的修正解。以此法得到的仿真结果与试验结果相吻合。     

Modeling urban heat islands in heterogeneous land surface and its correlation with impervious surface area by using night-time ASTER satellite data in highly urbanizing city,Delhi-India

The present study is an assessment and identification of urban heat island (UHI) in the environment of one of the fastest urbanizing city of India, Delhi Metropolis, employing satellite image of ASTER and Landsat 7 ETM+ in the thermal infrared region 3–14 μm. Temporal (2001 and 2005) ASTER datasets were used to analyze the spatial structure of the thermal urban environment subsequently urban heat island (UHI) in relation to the urban surface characteristics and land use/land cover (LULC). The study involves derivation of parameters governing the surface heat fluxes, constructing statistics of ASTER thermal infrared images along with validation through intensive in situ measurements. The average images reveal spatial and temporal variations of land surface temperature (LST) of night-time and distinct microclimatic patterns. Central Business District (CBD) of Delhi, (Connaught Place, a high density built up area), and commercial/industrial areas display heat islands condition with a temperature greater than 4 °C compared to the suburbs. The small increase in surface temperature at city level is mainly attributed to cumulative impact of human activities, changes in LULC pattern and vegetation density. In this study the methodology takes into account spatially-relative surface temperatures and impervious surface fraction value to measure surface UHI intensity between the urban land cover and rural surroundings. Both the spatial and temporal variation in surface temperature associated with impervious surface area (ISA) has been evaluated to assess the effect of urbanization on the local climate.     

CO2焊模糊波控逆变电源与平特性逆变电源焊接性能对比研究

本文介绍了CO2 焊模糊波控逆变电源的原理 ,对其焊接性能与带电子电抗器的平特性逆变电源作了对比研究。结果表明 :模糊波控逆变电源无论在焊接飞溅量 ,焊缝成型及可控性 ,还是在焊接过程的稳定性上都较带电子电抗器的平特性逆变电源有很大的提高。并对其原因进行了探讨     

沉淀硬化不锈钢的应用工艺探讨

阐述了沉淀硬化不锈钢（ＺＧｏＣｒ１６Ｎｉ４ＮｂＣｕ３）在铸造、热处理、无损探伤过程中易出现的问题及解决方法。