Film thickness measurement with an ultrasonic transducer

A technique for measuring condensate film thickness using an ultrasonic transducer is described. In the experiment, the condensate film thickness with R-113 and FC-72 (a fluorinert compound developed by the 3M Company) condensing on the horizontal lower surface of a rectangular duct was measured at several locations. From the measured values a power law relation between the condensate film thickness and the axial distance from the leading edge of the condensing surface was derived by regression analysis. Assuming a linear temperature profile in the condensate film, local and average heat transfer coefficients were computed from the condensate film thickness. The average heat transfer coefficients were compared with the values obtained by measuring the heat transfer rate to the coolant. The two values were within ±12% of each other. As yet there is no satisfactory analytical model to predict the local heat transfer coefficient even in the annular condensation regime. One of the main difficulties in modeling the condensation is the lack of a suitable model to predict the interfacial shear stress. With the measurement of the film thickness it is possible to determine the interfacial shear stress. It is hoped that the shear stresses so determined will lead to the development of a satisfactory model for interfacial shear stress with condensation.     

塑封硅器件中介电薄膜的温湿效应分析(英文)

随着铜互连以及low-k电介质在超大规模集成电路中地广泛使用,low-k电介质的机械完整性及其对互连可靠性变得更加重要。影响介电膜的机械完整性和互连可靠性的因素包括介电膜的工艺制程,芯片与封装材料的相互影响,以及环境温度和湿度的影响。本文研究集中于了解环境温度和湿度对塑封硅器件中介电薄膜的可靠性影响。采用快速温度和湿度实验条件,对塑封硅器件中介电薄膜受水分和温度损伤的敏感性进行了分析。运用商业有限元(FEA)分析软件,对水分在塑封材料和硅器件中的扩散过程进行了建模及仔细分析。并对硅器件周边密封圈的防水分扩散效力进行了研究。通过这一系列实验与分析,对塑封硅器件中介电薄膜的温湿效应有了完整地了解,并提出和建立了相关的物理模型和经验公式。运用这物理模型和经验公式可对在各种使用环境温度和湿度条件下,塑封硅器件中介电薄膜的可靠性进行评估及分析。     

润滑理论研究的进展与思考

全面阐述了润滑理论研究中关于各种润滑状态,包括流体润滑、边界润滑、弹流润滑、薄膜润滑以及混合润滑等的研究进展和存在的问题;并进而就今后的润滑理论研究提出了若干建议.     

Waves on the surface of a falling power-law fluid film

Waves that occur at the surface of a falling film of thin power-law fluid on a vertical plane are investigated. Using the method of integral relations an evolution equation is derived for two types of waves equation which are possible under long wave approximation. This equation reveals the presence of both kinematic and dynamic wave processes which may either act together or singularly dominate the wave field depending on the order of different parameters. It is shown that, at a small flow rate, kinematic waves dominate the flow field and the energy is acquired from the mean flow during the interaction of the waves, while, for high flow rate, inertial waves dominate and the energy comes from the kinematic waves. It is also found that this exchange of energy between kinematic and inertial waves strongly depends on the power-law index n. Linear stability analysis predicts the contribution of different terms in the wave mechanism. Further, it is found that the surface tension plays a double role: for a kinematic wave process, it exerts dissipative effects so that a finite amplitude case may be established, but for a dynamic wave process it yields dispersion. Further, it is shown that the non-Newtonian character n plays a vital role in controlling the role of the term that contains surface tension in the above processes.     

表面修饰硼酸盐润滑油添加剂的摩擦学性能

制备了表面修饰的硼酸盐润滑油添加剂（球形颗粒，粒径大都小于０．５μｍ），且用四球试验机研究了其摩擦学性能．结果表明：这种添加剂具有良好的极压抗磨减摩性能，当润滑油中元素Ｂ的质量分数为０．０５％时，四球磨斑直径最小，最大无卡咬负荷（ｐＢ值）最高；基础油的粘度和含水量对添加剂的极压抗磨性能有较大的影响，粘度为６５．３０ｍｍ２／ｓ时的极压抗磨性最好，水的质量分数为１％时的ｐＢ值最高，低于１％时的ｐＢ值比不含水时的高，水的质量分数高于１％时的ｐＢ值随水含量的增加而降低．Ｘ射线光电子能谱分析发现，表面修饰的硼酸盐润滑油添加剂在摩擦表面形成了一层混合的摩擦化学反应膜，其中元素Ｂ主要以ＢＮ的形式存在．     

Pore-scale network model for drainage-dominated three-phase flow in porous media

Drainage displacements in three-phase flow under strongly wetting conditions are completely described by a simple generalisation of well understood two-phase drainage mechanisms. As in two-phase flow, the sequence of throat invasions in three-phase flow is determined by fluid connectivity and threshold capillary pressure for the invading interface. Flow through wetting and intermediate spreading films is important in determining fluid recoveries and the progress of the displacement in three-phase flow. Viscous pressure drops associated with flow through films give rise to multiple filling and emptying of pores. A three-phase, two-dimensional network model based on the pore-scale fluid distributions and displacement mechanisms reported by Øren et al. and which accounts for flow through both wetting and intermediate fluid films is shown to correctly predict all the important characteristics of three-phase flow observed in glass micromodel experiments.     

A parametric study of laser induced thin film spallation

We report parametric studies of elastic wave generation by a pulsed laser and associated spalling of thin surface films by the corresponding high stresses. Two different substrate materials, single crystal Si (100) and fused silica, are considered. Spallation behavior of Al thin films is investigated as a function of substrate thickness, film thickness, laser energy, and various parameters governing the source. Surface displacement due to the stress wave is measured by Michaelson interferometry and used to infer the stresses on the film interface. Consistent with previous studies, the maximum stress in the substrate and at the film/substrate interface increases with increasing laser fluence. For many of the conditions tested, the substrate stress is large enough to damage the Si. Moreover, the maximum interface stress is found to increase with increasing film thickness, but decrease with increasing substrate thickness due to geometric attenuation. Of particular significance is the development of a decompression shock in the fused sillica substrates, which results in very high tensile stresses at the interface. This shock enhances the failure of thin film interfaces, especially in thicker samples.     

微管内气液两相流中液膜厚度的实验测量

微通道内气液两相流中气柱（plugbubble）与通道壁之间液膜厚度的实验测量，是微热管、微流动、微电子冷却以及气泡雾化等研究中普遍关注的问题。本文利用基于光学干涉和快速傅立叶变换的空间频谱分析方法，实验测量获取了含表面活性剂水中气柱在750μm通道内运动时其与通道壁面之间的液膜厚度。实验结果表明：表面活性剂对液膜厚度的影响比较明显，即当表面活性剂浓度在一定范围内增大时，液膜厚度会减小；此外，当气柱运动速度在一定范围内增大时，液膜厚度也会减小。     

Effects of interface dislocations on properties of ferroelectric thin films

Effects of interfacial dislocations on properties of thin-film ferroelectric materials, such as the self-polarization distribution, Curie temperature, dielectric constant and the switching behaviors, are investigated via the system dynamics based on the Landau-Devonshire functional. Dislocation generation in the film is found to reduce the overall self-polarization and the Curie temperature. The spatial variations are both very strong, particularly in the immediate neighborhood of the dislocation cores. In agreement with previous results based on a stationary model, a dead layer exists near the film/substrate interface, in which the average self-polarization is much reduced. Moreover, it is evident from our results that interface dislocations play an important role in suppressing the remnant polarization and the coercive field of the polarization.     

薄膜沿加热平板下落的稳定性分布

本文分析了薄膜沿加热平板下落的稳定性。在时间模式下，发现流动的不稳定性是由表面波不稳定和加毛细不稳定构成的，同时当流体的热扩散越大以及界面热量损失越小时，热毛细不稳定越剧烈，在时空模式下，流动随着Marangoni数的增大。流动有可能从对流不稳定过渡到绝对不稳定，这一结论尚待实验验证。