离子束溅射生成气敏膜的研究

本文对离子束溅射生成气敏膜作了研究。与烧结陶瓷气敏传感器比较，溅射生成气敏膜对乙醇气体具有灵敏度高，长期稳定，对其它气体选择性好，而且响应恢复时间快。采用Ｘ光衍射等手段分析了离子束溅射膜的品质，表明材料组织结构相同，与基片附着性好，组织致密。     

气敏膜光学传感特性研究

本文根据光传输理论导出介质消光系数,折射率与介质电磁参数,光波频率等的关系。     

低功耗烧结气敏元件制备和气敏特性研究

未经掺杂的金属氧化物半导体气敏传感器通常灵敏度很高，但选择性较差。为提高选择性和一致性，设计了一种特殊结构的低功耗SnO2烧结气敏元件的制备方法，测试了SnO2烧结气敏元件的气敏特性。制备的SnO2烧结气敏元件在40mW的加热功率条件下，100ppm的CO气氛中灵敏度达到3，响应时间仅为4s；在180mW的加热功率条件下，对氢和碳氢化合物（如CH4和LPG）敏感。这类低功耗烧结气敏元件选择性和一致性好，有望用于室内煤气泄漏检测等场合。     

掺杂对甲醛气敏元件气敏特性的改善

纳米材料SnO2对大多数VOC气体具有敏感性.文中以SnO2为基料制作了旁热式甲醛气敏元件,为改善甲醛气敏元件的气敏特性,选择了2%Sb,3%Sb,2%Pd,3%Pd,4种比例的掺杂材料,并以低体积分数甲醛作为测试气体,对SnO2气敏元件的气敏特性进行了测试.结果显示:掺杂2%Pd的气敏元件气敏特性良好.     

酞菁铜薄膜气敏光谱性能的研究

用真空升华方法制备酞菁桐（CuPc）薄膜，并测量了薄膜在不同浓度的NH3和乙醇气体中的透射光谱。实验发现CuPc薄膜对NH3浓度的变化有良好的响应，但乙醇浓度的变化不够敏感，特别是在高浓度时；退火处理不能改善膜片乙醇的敏感性能，而使膜片对NH3的响应变差。     

常温SnO2—Pd气敏元件的研制

采用共沉淀方法，制备了ＳｎＯ２和Ｐｄ粉两种主要敏感材料，研制成了常温ＳｎＯ２－Ｐｄ气敏元件。该元件功耗低，小于０．１Ｗ，对Ｈ２，煤气等灵敏，稳定，响应快，小于７Ｓ，恢复快，小于２５Ｓ。讨论了ＳｎＯｘ的结构与气敏性的关系。     

超微粒子气敏膜的制备

文中介绍用高频溅射方法制备了超微粒子气体敏感膜,研究了工艺参数对气敏膜的质量、性能的影响,并对气敏膜进行了测试,给出了试验曲线。     

半导体气敏元件基体材料的制备及特性

作者对常用的几种半导体气敏材料进行了研究探讨。本文重点介绍其制备方法及其相关特性。     

混气式喷涂法的原理及应用

我国现行的喷涂施工，普遍采用压缩空气喷涂法。它是将涂料从容器中吸出后通过压缩空气雾化。优点是适应性强、应用范围广、简便；缺点是环境污染严重、劳动保护不好、涂料利用率低（仅50％左右），且施工中若通风不良，易引起火灾，另外涂膜附着力不强、不实、不匀。50年代发明了高压元气喷涂法，它是通过专用设备将涂料加压，增压后的涂料通过细小的喷嘴雾化后喷射到工件上。优点是涂层厚，效率大大提高，涂料利用率达60％左右；缺点是不太适应表面形状复杂的装饰性产品，边散的漆雾较大，但比空气喷涂产生的漆雾要少一些。静电由徐是利用…     

一种提高气相色谱检测灵敏度的新方法——柱头瞬间加压法

本文提出一种提高气相色谱检测灵敏度的新方法-柱头瞬间加压法,探讨对不同化合物在不同加压时间和加压速率条件下对提高灵敏度的影响。实验结果表明,在现有仪器允许的操作范围内,该方法可以使被分析的样品检测灵敏度提高6~7倍。     

Non-absorbable gas effects on heat and mass transfer in falling film absorption

Film absorption involves simultaneous heat and mass transfer in the gas-liquid system. While the non-absorbable gas does not participate directly in the absorption process, its presence does affect the overall heat and mass transfer. An experimental study was performed to investigate the heat and mass transfer characteristics of LiBr-H₂O solution flowing over 6-row horizontal tubes with the water vapor absorption in the presence of non-absorbable gases. The volumetric concentration of non-absorbable gas. air, was varied from 0.17 to 10.0%. The combined effects of the solution flow rate and its concentration on the heat and mass transfer coefficients were also examined. The presence of 2% volumetric concentration of air resulted in a 25% reduction in the Nusselt number and 41% reduction in the Sherwood number. Optimum film Reynolds number was found to exist at which the heat and mass transfer reach their maximum value independent of air contents. Reduced Nusselt and Sherwood numbers, defined as the ratio of Nusselt and Sherwood numbers at given non-absorbable gas content to that with pure water vapor, were correlated to account for the reduction in the heat and mass transfer due to non-absorbable gases in a falling film absorption process.     

涡轮工作叶片内冷通道换热特性数值模拟

采用非结构化网格和SST紊流模型,求解三维N-S方程,对带90°肋和气膜孔的矩形通道在入口雷诺数60000,罗斯贝数0.11,气膜孔总出流比为0.22时的三维流场进行了数值模拟。分析了通道旋转和静止时各个面的换热变化规律。结果表明,通道静止时,不但布置了粗糙肋的上、下壁面换热得到了增强,光滑的侧壁换热同样获得了增强;通道旋转时流场更加复杂,旋转所产生的二次流动使各个壁面的换热进一步增强。     

In-situ heat treatment system for die steels using YAG laser with a machining center

We propose a laser heat treatment system for die steels using a YAG laser on the machine tool table. Optical fiber is used to transmit the laser light from a source to the machine tool table in this system, which makes it possible to perform the cutting processes, the heat treatment and the grinding processes with a machining center. In the present report, the experiments of laser heat treatment were done in order to research suitable die steels for this system. Additionally, the temperatures based on a theoretical model were investigated during the laser irradiation. As a result, it is clear that the martensite start temperature (Ms point) of materials is an important factor to estimate the application of this heat treatment.     

Molecular dynamics study on evaporation process of adherent molecules on surface by high temperature gas

Surface degreasing method with premixed flame is proposed as the removal method of adherent impurities on materials. Effects of adherent molecular thickness and surface potential energy on evaporation rate of adherent molecules and molecular evaporationmechanism were investigated and discussed in the present study. Evaporation processes of adherent molecules on surface molecules were simulated by the molecular dynamics method to understand thermal phenomena on evaporation processes of adherent molecules by using high temperature gas like burnt gas. The calculation system was composed of a high temperature gas region, an adherent molecular region and a surface molecular region. Both the thickness of adherent molecules and potential parameters affceted the evaporation rate of adherent molecules and evaporation mechanism in molecular scale.     

端面气膜密封的泄漏流特性

对面气膜密封的密封坝不带自由流的优越结构,其径向泄漏所流行应用的经典理论计算,结果偏高,误差较大。本文将采用修正准一维可压流分析方法,考察有关压差,坝宽,膜厚及旋转效应对径向泄漏流大小及其出现阻塞流的影响。     

Multi-range sensors for the measurement of liquid film thickness distributions based on electrical conductance

The paper presents an approach toward an enhancement of the measuring range of high-speed sensors for the measurement of liquid film thickness distributions based on electrical conductance. This type of sensors consists of electrodes mounted flush to the wall. The sampling of the current generated between a pair of neighboring electrode is used as a measure of the film thickness. Such sensors have a limited measuring range, which is proportional to the lateral distance between the electrodes. The range is therefore coupled to the spatial resolution. The proposed new design allows an extension of the film thickness range by combining electrode matrices of different resolution in one and the same sensor. In this way, a high spatial resolution is reached with a small thickness range, whereas a film thickness that exceeds the range of the high resolution measurement can still be acquired even though on the costs of a lower spatial resolution. A simultaneous signal acquisition with a sampling frequency of 3.2 kHz combines three measuring ranges for the characterization of a two-dimensional film thickness distribution: (1) thickness range 0–600 µm, lateral resolution 2×2 mm², (2) thickness range 400–1300 µm, lateral resolution 4×4 mm², and (3) thickness range 1000–3500 µm, lateral resolution 12×12 mm². The functionality of this concept sensor is demonstrated by tests in a horizontal wavy stratified air–water flow at ambient conditions. Using flexible printed circuit board technology to manufacture the sensor makes it possible to place the sensor at the inner surface of a circular pipe.     

Flow and heat transfer measurements of film injectant from a row of holes with compound angle orientations

An experiment has been conducted on the flow and heat transfer characteristics of film coolant injected from a row of five holes with compound angle orientations of 35° inclination angle and 45° orientation angle. The Reynolds number number based on the mainstream velocity and injection hole diameter 3.58 x10⁴. Three-dimensional velocity, film cooling effectiveness and heat transfer coefficient data are presented at three different mass flux ratios of 0.5, 1.0 and 2.0. Flow entrainment has been found between the vortices generated by adjacent injectants. The injectant with compound angle orientation entrains not only the mainstream boundary layer flow but also the adjacent injectant. Because of the flow entrainment, the injectant. With compound angle orientation is characterized by a single vortex while two bound vortices are usually observed in the case of simple angle injection. The strength of the secondary flow depends strongly on the mass flux ratio, which shows significant influence on the film cooling effectiveness and heat transfer coefficient.     

激光在机械制造领域中的应用及展望

综述了激光在切割、焊接、打孔、刻标记、辅助切削、成型、粉末烧结制模和热处理机械制造领域中应用的现状,并探讨了其发展前景。