Property improvement of multilayer TiN/Ti films with C~+ implantation

Using the MEVVA ion source, carbon ions have been implanted in TiN coatings deposited by multi-arc ion plating The Vickers microhardness of the C+ -implanted TiN films increased with the increase in the ion flux and dose. X-ray diffraction (XRD) analysis showed that the TiC phases had been formed in the films. In addition, the films had the preferred growth orientations of TiN and TiC, both of which were (111) orientation after annealing at 500℃ for 30 min. Auger electron spectra analysis indicated that C+ -implanted profile was in typical Gaussian-like distribution in single films. The distribution with multipeaks of C atoms was obtained in multi-layer TiN/Ti. The possibility of the multilayer films (Ti (C, N)/TiN/Ti(C, N)/TiN and Ti(C, N)/TiC/Ti(C, N)/TiC) forming using the C-implanted TiN/Ti films is presented for the first time.     

多层薄膜结构气敏效应研究

在SnO2气敏薄膜层上覆盖一层或多层钝化材料（SiO2,Al2O3) 薄膜，制成的多层膜气敏元件，可很好地排除大分子气体如乙醇等对小分子H2检测的干扰，使其具有单独检测H2的功能。本文还通过测量元件的升温曲线，推导出敏感体表面的氧吸附活化能；找出活化能与灵敏度、选择性的关系。根据实验现象和物性分析结果，试着探讨了元件的敏感机理。     

多弧离子镀与磁控溅射共沉积TiN/TiCN多层膜的高温抗氧化性能

TiN/TiCN多层膜的高温抗氧化性研究对于扩大其应用领域具有重要作用,但目前鲜见相关报道。采用多弧离子镀与磁控溅射技术以不同调制周期在304不锈钢表面共沉积TiN/TiCN多层膜。采用XRD、XPS、倒置显微镜及高温氧化试验研究了多层膜的高温抗氧化行为。结果表明:TiN/TiCN多层膜表面光滑平整、均匀致密,薄膜主要为具有Ti-(C,N)键的fcc-TiN结构;随着调制周期的减小,TiN/TiCN多层膜生长取向发生转变,且具有(111)晶面生长织构;随着氧化温度的升高,多层膜的显微硬度逐渐降低,氧化增重速率不断增大,且在700℃之后变化速率较快,薄膜的开始氧化温度约为750℃;随着调制周期的减小,多层膜TiN与TiCN界面层数量增多,促使晶粒细化,提高了其致密性,还隔断了缺陷贯穿薄膜的连续性,显著降低了薄膜的孔隙率,致使O原子扩散困难,增强了薄膜的高温抗氧化性能。     

Development of Spectral Selective Multilayer Film for a Variable Emittance Device and Its Radiation Properties Measurements

A smart radiation device (SRD) that is a variable emittance radiator has been developed as a thermal control material for spacecraft. The SRD has the unique feature of large variation of the total hemispherical emittance _H near room temperature. The _H of the SRD changes depending on its temperature. However, there is a drawback of a large solar absorptance _S. It is too large to use as a thermal control material for spacecraft. In order to reduce the large _S, spectral selective multilayer film was developed. This multilayer film reflects solar radiation and transmits far-infrared radiation to maintain the variation in the _H of the SRD. This paper presents thermal radiative properties of the SRD with spectral selective multilayer film. The multilayer film was designed by using a genetic algorithm (GA). The designed multilayer film was evaporated on the surface of the SRD by the electron beam evaporation method. The experimental results of _S and _H of the SRD with the multilayer film agreed well with calculated results.     

Efficient and accurate multilayer solid‐shell element: non‐linear materials at finite strain

We present in this paper an efficient and accurate low‐order solid‐shell element formulation for analyses of large deformable multilayer shell structures with non‐linear materials. The element has only displacement degrees of freedom (dofs), and an optimal number of enhancing assumed strain (EAS) parameters to pass the patch tests (both membrane and out‐of‐plane bending) and to remedy volumetric locking. Based on the mixed Fraeijs de Veubeke‐Hu‐Washizu (FHW) variational principle, the in‐plane and out‐of‐plane bending behaviours are improved and the locking associated with (nearly) incompressible materials is avoided via a new efficient enhancement of strain tensor. Shear locking and curvature thickness locking are resolved effectively by using the assumed natural strain (ANS) method. Two non‐linear 3‐D constitutive models (Mooney–Rivlin material and hyperelastoplastic material at finite strain) are applied directly without requiring the enforcement of the plane‐stress assumption. In particular, we give a simple derivation for the hyperelastoplastic model using spectral representations. In addition, the present element has a well‐defined lumped mass matrix, and provides double‐side contact surfaces for shell contact problems. With the dynamics referred to a fixed inertial frame, the present element can be used to analyse multilayer shell structures undergoing large overall motion. Numerical examples involving static analyses and implicit/explicit dynamic analyses of multilayer shell structures with both material and geometric non‐linearities are presented, and compared with existing results obtained from other shell elements and from a meshless method. It is shown that elements that did not pass the out‐of‐plane bending patch test could not provide accurate results, as compared to the present element formulation, which passed the out‐of‐plane bending patch test. The present element proves to be versatile and efficient in the modelling and analyses of general non‐linear composite multilayer shell structures. Copyright © 2005 John Wiley & Sons, Ltd.     

膜层厚度对CuPc/ZnS多层复合薄膜光电性能的影响

为了找到制备CuPc ZnS多层复合膜薄膜最佳光电导性能的参数 ,本文研究了CuPc ZnS多层复合膜的CuPc膜层的厚度系列、ZnS膜层的厚度系列的光电导性能和结构 ,利用表面电位衰减仪、紫外 -可见光谱仪和X射线衍射仪等设备分析了复合薄膜的光电导性能和结构及其关系 ,探讨了改变CuPc、ZnS膜层的厚度对CuPc ZnS多层复合膜薄膜的光电导性能和结构的影响     

纳米结构镀层的制备及其应用

对近年来国外纳米结构镀层研究的文献进行了综述,介绍了纳米晶镀层、纳米颗粒增强镀层、纳米多层镀层的制备方法、性能特点及应用的最新进展.     

NaAlH4空间约束体系的构建及其脱/加氢行为

配位氢化物具有较高的质量储氢密度,已成为国内外储氢材料的研究热点,但尚未解决的脱/加氢温度过高、速率慢和可逆性差等问题是制约其实际应用的主要原因.利用孔性材料的结构特点来构建纳米尺度的空间约束体系,可有效地改善配位氢化物的脱/加氢性能.以NaAlH4为例,介绍了孔性材料的制备和表面修饰,分析了配位氢化物/孔性介质空间约束体系的构建及其且兑/加氢行为.这种空间约束体系为改善配位氢化物的储氢性能提供了一条新途径.进一步构建配位氢化物/孔性介质/催化剂的空间约束体系,实现对配位氢化物的复合催化,将是今后努力的方向.     

Probing Distinctive Electron Conduction in Multilayer Rhenium Disulfide

Charge carrier transport in multilayer van der Waals (vdW) materials, which comprise multiple conducting layers, is well described using Thomas–Fermi charge screening (λ_TF) and interlayer resistance (R_int). When both effects occur in carrier transport, a channel centroid migrates along the c‐axis according to a vertical electrostatic force, causing redistribution of the conduction centroid in a multilayer system, unlike a conventional bulk material. Thus far, numerous unique properties of vdW materials are discovered, but direct evidence for distinctive charge transport behavior in 2D layered materials is not demonstrated. Herein, the distinctive electron conduction features are reported in a multilayer rhenium disulfide (ReS₂), which provides decoupled vdW interaction between adjacent layers and much high interlayer resistivity in comparison with other transition‐metal dichalcogenides materials. The existence of two plateaus in its transconductance curve clearly reveals the relocation of conduction paths with respect to the top and bottom surfaces, which is rationalized by a theoretical resistor network model by accounting of λ_TF and R_int coupling. The effective tunneling distance probed via low‐frequency noise spectroscopy further supports the shift of electron conduction channel along the thickness of ReS₂.