硅台面结构凸角腐蚀原因探析

本文探讨了硅台面结构凸角腐蚀的原因。指出非理想的直角掩膜结构导致了凸角腐蚀，凸角处侧壁由横向腐蚀速率最快的晶面所构成。     

体硅湿法加工中凸角切削现象的分析

以硅(100)衬底为基础,详细介绍了一种针对体硅湿法加工中各向异性腐蚀带来的凸角切削现象的理论分析方法,指出了凸角切削现象具有唯一性和方向性的结论.该方法首先对凸角侧边类型进行划分,再利用现有理论资源,对凸角侧边和切削方向在凸角顶点的折算速率进行严格的数学计算和比较,最终确定腐蚀结束后的形变结构.选择了正五边形以及不规则六边形为代表,展示了该方法的实现过程,最后给出的模拟和实验结果都证实了该方法的正确有效.     

用3D动态元胞自动机模型模拟硅的各向异性腐蚀过程

建立了硅各向异性腐蚀的3D动态元胞自动机模型,模拟过程中表层元胞边界条件的确定只与表层元胞有关,简化了表层元胞边界条件的确定过程.此外,腐蚀模拟过程中只需要计算与腐蚀液接触的表面元胞的腐蚀过程,提高了模拟计算的速度.采用不同的掩模图形,模拟了硅的各向异性腐蚀过程,通过对模拟结果的理论分析及将模拟的三维输出结果与已有实验结果进行对比,验证了模型的模拟效果.     

硅各向异性腐蚀模拟的3-D连续CA模型研究

针对硅的各向异性腐蚀，直接采用硅的晶格结构作为CA（元胞自动机）的晶格结构，建立了硅各向异性腐蚀的3D连续CA模型。模型通过引入更多腐蚀过程中出现的晶面，使得腐蚀过程中表层元胞边界条件的确定只与表层元胞有关，提高了模拟的精度。通过对模似结果的理论分析及将模拟的三维输出结果与已有实验结果进行对比，验证了模型的模拟效果。     

氢氧化钾各向异性腐蚀制作近似圆形单晶硅膜的掩膜补偿技术

本文介绍我们通过掩膜图形的设计,在（１００）单晶硅上利用氢氧化钾各向异性腐蚀制作错综复杂的正八边形单晶硅膜的方法。据此技术可获得最小外接圆半径仅为腐蚀深度的２．６７倍的小尺寸正八边形单晶硅膜,其力学性能大大优于同样面积的等厚方形单晶硅膜,满足微动力机械的要求。     

硅基周期槽结构的刻蚀工艺研究

针对微电子机械系统(MEMS)湿法槽刻蚀技术,基于硅材料各向异性腐蚀特性研究了硅基周期槽的湿法刻蚀工艺,得出了优化的光刻参数。通过对比实验详细分析了搅拌在腐蚀过程中起到的重要作用,实验结果显示,搅拌可以增加腐蚀溶液的流通性,使硅表面不易产生气泡形成"伪掩膜"阻碍反应的进行,从而制备出表面光滑平整的周期槽结构。同时,在搅拌的条件下对槽深和腐蚀时间的关系也做出了相应的分析。为硅微机械加工技术的进一步研究提供了参考。     

表面无序亚微米结构高效扩散膜

提出了表面无序亚微米结构高雾度和高透光率扩散膜的制备方法。通过模板复制法,基于硅锥模板和阳极氧化铝模板制备了具有表面无序亚微米结构的聚二甲基硅氧烷(PDMS)和聚苯乙烯(PS)薄膜。结果表明,表面无序亚微米结构可以显著增加薄膜的雾度。结构的形貌和尺寸对薄膜光扩散性能有重要影响,其中利用锥径650nm的硅锥模板得到的具有表面无序亚微米孔结构的PDMS薄膜的雾度达到92%,透光率为90.9%,有效散射系数为83.7%;同一模板制备的PS薄膜的雾度达到97.9%,透光率为85%,有效散射系数为83.2%;这二种微结构薄膜都可用作高效扩散膜。结果表明:利用硅锥模板制备这种高效扩散膜,工艺简单、成本低,对聚合物材料没有选择性,有望实现高性能扩散膜的大规模生产。     

VC对微米级Ti(CN)基金属陶瓷微观结构和力学性能的影响

VC对于制备微米级的Ti(CN)基金属陶瓷,能够起到控制Ti(CN)晶粒长大的作用,并且能够使烧结体中晶粒粒度分布变得均匀。在液相烧结过程中,由于瓦尔德熟化效应使Ti(CN)晶粒长大,Ti(CN)晶粒的长大又分为连续长大和不连续长大。关于VC的抑制机理,目前还没有明确的结论,但有三种比较有代表性的说法:吸附机制、溶解机制和偏析机制。随着VC添加量的增加,Ti(CN)基金属陶瓷的抗弯强度呈现先升后降的趋势;VC的加入使材料的硬度减小。     

预腐蚀对30CrMnSiNi2A连接件疲劳寿命影响的试验研究

某型飞机疲劳关键件为30CrMnSiNi2A螺钉连接件,为了进行腐蚀条件下疲劳寿命评定,考虑地面停放预腐蚀的影响,采用周期浸润加速腐蚀试验方法,进行不同预腐蚀时间后在随机谱和两种恒幅谱下的成组疲劳试验.结果表明,疲劳寿命随腐蚀时间的增加而降低;在工程常用的时间范围内,若假定疲劳寿命服从对数正态分布,对数疲劳寿命标准差与预腐蚀时间基本无关;若假设疲劳寿命服从威布尔分布,其形状参数与预腐蚀时间基本无关.并以预腐蚀影响系数C(t)反映预腐蚀对疲劳寿命的影响,研究预腐蚀对30CrMnSiNi2A连接件疲劳寿命的影响.     

WNS型锅壳式燃油(气)锅炉烟气侧腐蚀的原因与防止办法

分析了低温腐蚀的机理,认为锅壳式燃油(气)热水锅炉受热面烟气侧腐蚀的主要原因是燃料中硫分高和壁温低,并提出了减轻和防止腐蚀的办法．     

Electric field-induced changes of W(110) and W(111) tips

Using field emission and scanning electron microscopy we have studied the influence of strong electric fields on the thermally induced growth behaviour of field emission tips. For smaller fields (i.e. smaller than needed for a satisfactory field emission image) we observe an enlargement of low-index faces, which for higher fields develops into a building-up of micro-structures and roughening on the initially spherical part of the tip surface. In an intermediate state only the region near the (111) directions contributes to the field emission pattern. For the highest fields employed the results indicate the growth of local protrusions preferentially near (100) faces. Our results show that in scanning tunnelling microscopy W(111) tips should be superior to the commonly used W(110) tips.     

Voltage-dependent imaging of antimony on the GaAs(110) surface

Using a scanning tunnelling microscope, voltage-dependent imaging of antimony on the GaAs(110) surface has been performed. For negative sample voltages, the images reflect surface dangling bonds. Depending on the magnitude of the voltage, either one or both of the Sb atoms in the surface unit cell are seen. At positive voltage the density of surface-states is observed to be greatly reduced compared to negative voltages. The results are analysed within the context of a simple tight-binding model for a one-dimensional biatomic chain.     

Structure of the (110) antiphase boundary in gallium phosphide

The morphology of antiphase boundaries in GaP films grown by molecular beam epitaxy on Si (001) has been studied by transmission electron microscopy. The inversion of the crystal polarity between antiphase domains was confirmed by convergent‐beam electron diffraction. The APBs were often found to facet parallel to {110} planes. Strong‐beam α‐fringe contrast observed along the (110) facets indicates that adjacent antiphase domains are related by an additional rigid‐body lattice translation. Diffraction‐contrast analysis shows that this R corresponds to a shear parallel to the [001] direction and a small expansion. The magnitude of the translation was inferred, quantitatively, through a comparison between energy‐filtered zero‐loss images of the α‐fringe contrast with numerical calculations. The components of the rigid‐body lattice translation were determined to be 0.023 ± 0.0033 nm in the [001] direction and 0.005 ± 0.002 nm in the 0 direction. Based upon a geometric model of the {110} antiphase boundary, the lengths of the Ga and P antisite bonds were calculated to be 254 ± 2 pm and 227 ± 4 pm, respectively.     

A real space investigation of the dimer defect structure of Si(001)-(2times8)

The atomic arrangement of the Si(001)-(2 times 8) surface has been directly imaged in real space by scanning tunnelling microscopy. The superstructure is impurity induced and stablilized by as little as 1% Ni. Clean Si(001) surfaces do not form the (2times8) phase. The two-dimensional Fourier transforms of the STM topographs correspond well to the (2times8) LEED pattern, but the real space images are in fact considerably more complex than previously concluded on the basis of recent diffraction technique measurements. The STM images clearly demonstrate that the (2times8) surface consists of a complex missing dimer structure, namely one and multiple dimer vacancies. Such a dimer defect appears related to the Ni impurity and intimately related to the ordering of the dimer defects probably by third layer dimerization to produce quasi-ordered ‘channels’.     

用同位素稀释电感耦合等离子体质谱法测定海水中的痕量铅

5 -磺基 -8-羟基喹啉用作微柱流动注射在线分离、富集和电感耦合等离子体质谱分析流程中的螯合剂 ,与铅反应生成铅螯合物被硅酸镁吸附剂吸附 ,实现痕量铅的分离、富集。对联用系统的参数如螯合剂用量、淋洗条件、洗脱条件和进样量等进行最优化 ,测定标准水样和加标海水的铅回收率分别为 1 0 1 %和 97.9% ,相对标准偏差为± 0 .98% ,检测限为 0 .2 0 4 μg/ L。可应用于生物、环境等高盐样品中铅的在线分离测定     

Boundary Lubrication of Oxide Surfaces by Poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) in Aqueous Media

In this work, we have explored the application of poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) as an additive to improve the lubricating properties of water for metal-oxide-based tribo-systems. The adsorption behavior of the polymer onto both silicon oxide and iron oxide has been characterized by optical waveguide lightmode spectroscopy (OWLS). Several tribological approaches, including ultra-thin-film interferometry, the mini traction machine (MTM), and pin-on-disk tribometry, have been employed to characterize the frictional properties of the oxide tribo-systems in various contact regimes. The polymer appears to form a protective layer on the tribological interface in aqueous buffer solution and improves both the load-carrying and boundary-layer-lubrication properties of water.     

DTII(A)型带式输送机CAD数据库系统的开发

通过对DTII（A）型带式输送机设计选型及绘图过程的研究,以AutoCAD软件为开发平台,利用VB语言结合VFP数据库,开发了一套实用的DTII（A）型带式输送机CAD系统,实现了DTII（A）型带式输送机的原始参数输入、设计计算、部件选型、设计选型、说明书输出、图纸绘制等的一条龙CAD设计。它不仅可以提高设计计算的准确性,缩短设计选型时间,减轻技术人员的劳动强度,而且对于今后其它类型带式输送机CAD软件的开发也有一定的借鉴意义。     

一种管道中T(0,1)模态单向电磁超声换能器

为了准确判定管道中缺陷位置且减少回波信号复杂程度,提出一种管道中单向传播的电磁超声换能器结构.根据电磁超声换能器理论,建立磁场、位移、超声波叠加数学模型,并对单向电磁超声换能器波动位移进行有限元仿真分析;实验采用双线圈激励方法对T(0,1)模态导波的传播强度进行控制.结果表明:换能器相邻导线间距为λ/4,且延迟时间为T...     

A numerical analysis on the curved bileaflet mechanical heart valve (mhv): leaflet motion and blood flow in an elastic blood vessel

In blood flow passing through the mechanical heart valve (MHV) and elastic blood vessel, hemolysis and platelet activation causing thrombus formation can be seen owing to the shear stress in the blood. Also, fracture and deformation of leaflets can be observed depending on the shape and material properties of the leaflets which is opened and closed in a cycle. Hence, comprehensive study is needed on the hemodynamics which is associated with the motion of leaflet and elastic blood vessel in terms of fluid-structure interaction. In this paper, a numerical analysis has been performed for a three-dimensional pulsatile blood flow associated with the elastic blood vessel and curved bileaflet for multiple cycles in light of fluid-structure interaction. From this analysis fluttering phenomenon and rebound of the leaflet have been observed and recirculation and regurgitation have been found in the flow fields of the blood. Also, the pressure distribution and the radial displacement of the elastic blood vessel have been obtained. The motion of the leaflet and flow fields of the blood have shown similar tendency compared with the previous experiments carried out in other studies. The present study can contribute to the design methodology for the curved bileaflet mechanical heart valve. Furthermore, the proposed fluid-structure interaction method will be effectively used in various fields where the interaction between fluid flow and structure are involved.     

2-(4-取代苯基)咪唑并[5,6-f]邻菲咯晽化合物的ESI-MSn研究

The mass spectrometric behavior of six 2-(4-arylphenyl)imidazo[4,5-f]-[1,10]phenanthroline compounds were investigated by the electrospray inonization multiple stage mass spectrometry. The fragmentation pathway of the compounds were depended on the group of 4-arylphenyl. When the 4-substituent group was an activating one, the fragmentation usually took place in the phenyl. While the 4-substituent group was deactivating, the fragmentation took place in the imidazole ring.