Diffusion-limited evaporation of thin polar liquid films

The stability of evaporating very thin films of a polar liquid is investigated. The microscopic interaction with the substrate and capillarity are taken into account in a lubrication equation. The stability of a flat interface is studied when evaporation is limited by the diffusion of the vapour in the gas phase. The evaporation rate is computed and evaporation is shown to be stabilizing. A stability phase diagram is obtained. A weakly nonlinear analysis leads to a film-thickness amplitude equation that is non local in space. Physical consequences of the results are eventually discussed.     

Tribological and thermal stability study of nanoporous amorphous boron carbide films prepared by pulsed plasma chemical vapor deposition

Abstract

In this work, the thermal stability and the oxidation and tribological behavior of nanoporous a-BC:H films are studied and compared with those in conventional diamond-like carbon (DLC) films. a-BC:H films were deposited by pulsed plasma chemical vapor deposition using B(CH₃)₃ gas as the boron source. A DLC interlayer was used to prevent the a-BC:H film delamination produced by oxidation. Thermal stability of a-BC:H films, with no delamination signs after annealing at 500 °C for 1 h, is better than that of the DLC films, which completely disappeared under the same conditions. Tribological test results indicate that the a-BC:H films, even with lower nanoindentation hardness than the DLC films, show an excellent boundary oil lubricated behavior, with lower friction coefficient and reduce the wear rate of counter materials than those on the DLC film. The good materials properties such as low modulus of elasticity and the formation of micropores from the original nanopores during boundary regimes explain this better performance. Results show that porous a-BC:H films may be an alternative for segmented DLC films in applications where severe tribological conditions and complex shapes exist, so surface patterning is unfeasible.     

润滑的状态转化

报道了薄膜润滑的本质以及它与弹流润滑和边界润滑间关系的研究结果。根据各种特性膜厚度的变化分析了各润滑状态之间的转化关系，提出了润滑状态与宏观摩擦副所处状态关联与区分准则。     

粘-温修正的等效粘度模型分析研究

在等效粘度模型的基础上，考虑温度对润滑剂粘度的影响，建立了粘-温修正的等效粘度分析计算模型，并运用该模型进行薄膜润滑条件下的轴承性能分析计算，得到了不同参数下轴承性能的变化规律。     

纳米晶化对CoNbZr薄膜结构及阻抗的影响

采用独特的快速循环纳米晶化技术,对直流磁控溅射制备的非晶CoNbZr软磁膜,进行纳米晶化。研究了在不同的纳米晶化工艺条件下．薄膜的微观结构和阻抗性能。CoNbZr软磁薄膜晶粒细化到30nm．阻抗值从20Ω增加到100Ω(1400MHz),阻抗共振峰向低频移动200MHz左右．极大改善了薄膜的软磁性能。     

薄膜润滑研究的回顾与展望

薄膜润滑是20世纪90年代以来广泛研究的新型润滑状态。它是界于弹流润滑和边界润滑之间的一种过渡润滑状态，有着自己独特的润滑规律。文章回顾了薄膜润滑的研究历史，包括薄膜润滑概念的提出、测试技术的发展、薄膜润滑的膜厚特性、润滑机理探索以及计算理论等方面的研究成果与主要进展。     

Picosecond thermal pulses in thin gold films

In this paper it has been shown that, with the advent of lasers with a very short pulse duration, the effect of thermal wave propagation becomes important. To consider this effect, hyperbolic heat conduction in thin gold films was studied. It was shown that for heat fluxes of the order 10⁸ W·cm^–2, a thermal wave is generated in thin gold films. The consideration of the hyperbolicity of heat transfer enables one to describe the temperature profile with one value of fluence.     

Sulfidation growth and characterization of nanocrystalline ZnS thin films

Nanocrystalline ZnS thin films are prepared on glass and quartz substrates by sulfurizing ZnO thin films in the H₂S-containing mixture at 500 °C. These films are investigated by X-ray diffraction, scanning electron morphology, optical transmittance and photoluminescence spectra. The results show that the ZnS thin films have the hexagonal structure with a c-axis preferred orientation. Also, these nanostructure ZnS thin films with the grain size of ∼50 nm along the c-axis, exhibit the optical transparency as high as ∼80% in the visible region. It is found that sulfur replacement of oxygen sites in crystal lattices and recrystallization can take place during sulfidation, resulting in an evident increase of the grain size for the sulfurized films. Under the optimum sulfidation time of 2 h, the resultant ZnS thin films have a high crystallinity, low defect concentration and good optical properties with the band gap of 3.66 eV.     

铝诱导非晶硅薄膜快速低温晶化研究

采用金属铝诱导晶化非晶硅薄膜的方法制备多晶硅薄膜。研究了不同的退火温度对a-Si薄膜晶化的影响，采用XRD，Raman，SEM等测试手段分析了实验结果。实验结果发现非晶硅薄膜在400℃下退火20min薄膜仍为非晶结构（a-Si），在450℃下退火20min后非晶硅开始晶化且随着温度的升高，且晶化程度加强。     

On circular Bragg regimes in ellipsometry spectra of ambichiral sculptured thin films

The generalized ellipsometry formalism was used for a right-handed ambichiral sculptured thin film. The amplitude ratios and phase differences were calculated using an experimental dielectric function for bulk titania. The results showed that the occurrence of the circular Bragg regimes can be adduced from ellipsometry spectra.     

Flow of surfactant-laden thin films down an inclined plane

A theory is formulated to describe the dynamics of a thin film flowing down an inclined plane laden with insoluble surfactant, present in dilute concentrations. Use of lubrication theory yields a coupled pair of partial differential equations for the film height and surfactant monolayer concentration. The contact line singularity is relieved by assuming the presence of a thin precursor layer ahead of the advancing film. Base flow solutions for a flow of constant flux are examined over various inclination angle, precursor-layer thickness, Peclet number, and capillary parameter ranges. Application of a transient growth analysis highlights the presence of an instability and the vulnerability of the flow to transverse disturbances of intermediate wavenumber. Our results reveal that several key features of the much-studied uncontaminated film flow, including stability, are modified qualitatively by the inclusion of surfactant.     

On optical rotation and selective transmission in ambichiral sculptured thin films

The optical rotation and selective transmission spectra of ambichiral sculptured thin films were calculated using the transfer matrix method. The results of optical modeling showed that at lower angular rotations the optical characteristics of ambichiral sculptured thin films are the same as chiral sculptured thin films. At higher angular rotations, two circular Bragg regimes appear. An ambichiral sculptured thin film in one regime reflects left circularly polarized (LCP) light and in a second regime reflects right circularly polarized (RCP) light. The optical properties of ambichiral sculptured thin films with twist and layer defects as spectral holes are also reported.     

薄膜润滑径向轴承特性分析

薄膜润滑轴承的特性远不同于常规轴承，在考虑间隙对润滑剂产生的影响后，润滑剂的特性将发生较大的变化。由于这种变化，薄膜润滑的特性才被广泛地研究和重视。文章应用等效粘度修正模型对径向滑动轴承进行了性能分析,对无限宽轴承可得出压力计算的解析表达式,从而可精确地计算轴承的性能。     

Thickness-controlled hydrophobicity of fibrous Parylene-C films

Fibrous Parylene-C films with tilted columnar morphology were deposited with a physicochemical version of the oblique-angle deposition (OAD) technique. Advancing contact angles increased from 103.9° (smooth hydrophobic surface) to 168.5° (rough superhydrophobic surface) as the thickness of the film increased from ∼ 100 nm to ∼ 60 μm, reflecting changes in the morphology of the top surface. Treatment with oxygen plasma can render these fibrous films completely water wettable. These techniques allow tailoring of surface wettability to meet the demands of specific biomedical applications.     

指数型粘度修正模型及应用

根据吸附理论和分子间能量的变化规律来确定表面相互作用程度，以此可定义吸附层，得出吸附层厚度的分析计算式。吸附层厚度对研究薄膜润滑是最关键的因素，是薄膜与厚膜不同分析的关键点。根据分子相互作用的基本理论及流体力学的基本定义得出指数型粘度修正的表达式，用于确定微小间隙内流体粘度的变化规律，从而建立薄膜润滑理论模型，计算薄膜润滑轴承的特性。     

Channel cracking in thin films on substrates of finite thickness

Solutions are presented for the elastic plane-strain problem of a crack in a coating on a compliant substrate of finite thickness. Analysis of the problem shows that substrate thickness has a significant effect on the steady-state energy release rate for channel cracks. This is so over a wide range of elastic mismatch between film and substrate, but is especially important if the substrate is more compliant than the film. Relaxation of the film stress due to elastic deformation of the substrate also plays an important role. If the substrate is clamped around the edge, as would be the case for a coated membrane, the stress in the coating cannot relax and the energy release rate for channel cracking increases significantly with decreasing substrate thickness. If the film stress is allowed to relax, however, the driving force for cracking is reduced as the substrate thickness decreases. The results from this study are used to evaluate the change in curvature of a film/substrate assembly due to channel cracking, a quantity that is of interest for the experimental determination of stresses in thin films. An expression for the elastic extension of the substrate due to channel cracking is derived making it possible to evaluate the effect of cracking on the mechanical behavior of bilayer membranes. It is expected that the present study may lead to the development of new experimental techniques for measuring the fracture toughness of thin coatings.     

石墨烯基薄膜作为固体润滑材料的研究现状及展望

近年来,微型机械系统对摩擦接触表面和界面性能的要求越来越高,表界面设计与改性问题亟待解决.石墨烯自发现以来,由于具有高机械强度、超薄的厚度、原子级光滑表面及低的层间剪切力和高的化学稳定性,作为表面固体润滑材料在摩擦学领域成为研究热点.本文主要介绍了石墨烯及其衍生物薄膜材料的制备方法,作为固体润滑材料在摩擦学方面的研究现...     

连续粘变条件下的速度场分析

流体的流动状态将直接影响轴承的润滑特性，轴承的润滑特性主要由润滑剂的粘度决定。工作中润滑剂的粘度变化影响其运动速度的变化，从而影响润滑剂的温升及内剪切稀化的程度等。尤其在薄膜润滑中，润滑膜的厚度极小，润滑剂流体粒子间的相对运动速度增大，其润滑剂特性的变化更为突出。以连续变化的粘度修正模型来研究在微小间隙内润滑剂的速度特性，得出间隙内速度的分布规律，为研究薄膜流体温度场和剪切稀化问题提供计算数据。     

ZnO薄膜应用的最新研究进展

ZnO是一种新型的Ⅱ-Ⅵ族半导体材料。详细介绍了ZnO薄膜在太阳能电池、表面声波器件、气敏元件、压敏器件等领域的应用以及在紫外探测器、LED、LD等潜在应用领域研究开发的最新进展。     

ZnO薄膜的p型掺杂研究进展

ZnO作为重要的第三代半导体材料在光电领域具有广泛的应用前景因而引起越来越多的关注,ZnO薄膜的p型掺杂是实现ZnO基光电器件的关键,也是ZnO材料的主要研究课题.本文论述了ZnO薄膜P型转变的难点及其解决方法,概述了ZnO薄膜p型掺杂的研究现状,提出了有待进一步研究的问题.