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1.
TiN存在高温氧化不良、固有脆性等缺点。将硅混合到TiN网络中,形成Ti-Si-N纳米多层膜,此纳米多层膜的硬度有了显著的提高。Ti-Si-N纳米多层膜是一类有着广阔应用前景的新材料,它在涂料、航空航天工业、电子器件等众多领域都有着广泛的应用。尤其在硬质合金刀具领域,较高的硬度、较好的耐磨性和韧性能够延长刀具的使用寿命。Ti-Si-N纳米多层膜制备方法有物理气相沉积和化学气相沉积两大类。物理气相沉积法是原材料在腔体的一端蒸发,然后沉积在腔体另一端较冷的基体上的方法。化学气相沉积在高温下发生化学反应,使钛、硅、氮原子发生重新组合,在基体表面生成Ti-Si-N纳米多层膜。与物理气相沉积方法相比,化学气相沉积方法需要的温度更高,并且化学反应中存在SiH 4等危险性气体,不适合大规模工业生产。Ti-Si-N纳米多层膜的性能主要受Si含量、调制周期和热处理温度等影响。随着Si含量的增加,纳米多层膜的性能先增强后减弱,Si含量在2.76%(质量分数)时,纳米多层膜硬度最大,摩擦系数最小。不同调制周期的多层膜性能优于单层膜,调制周期为0.7 nm时,纳米多层膜硬度达到28.7 GPa,弹性模量为301.1 GPa。随着退火温度的升高,纳米多层膜的附着性先增强后减弱,温度在800~950℃时,纳米多层膜硬度达到(49.7±0.83) GPa,结合力为83 N。纳米多层膜有超硬性,耐磨性和耐高温氧化性。对于纳米多层膜的超硬性,不同学者提出了不同的强化理论:交变应力场、模量差和Hall-petch强化理论;通过摩擦磨损实验可以判断纳米多层膜的磨损机制;在TiN中加入Si,生成的Ti-Si-N纳米多层膜具有耐高温氧化性。  相似文献   

2.
基于修正的镶嵌原子势,采用分子动力学方法建立多粒子系统模型,研究了面心立方晶格(FCC)和体心立方晶格(BCC)纳米金属薄膜的力学性能和拉伸破坏过程,分析了不同晶格结构纳米金属薄膜在拉伸变形时的能量、应力和构型变化过程,得到纳米单晶镍和α-铁薄膜的弹性模量、断裂强度、屈服强度.模拟表明FCC薄膜的拉伸断裂符合Griffith断裂理论;BCC薄膜的断裂过程有较长屈服阶段,自由表面对初始弹性模量的软化作用明显.  相似文献   

3.
本文利用高真空离子束辅助沉积系统(IBAD),在室温下制备了ZrN、TiAlN和一系列ZxN/TiAlN纳米多层膜,利用XRD、纳米力学测试系统和多功能材料表面性能实验仪,分析了束流和基底温度对薄膜的微结构和机械性能的影响.结果表明大部分多层膜的纳米硬度与弹性模量值都高于两种个体材料硬度的平均值,当辅助束流为5 mA时,多层膜硬度达到30.6 GPa.基底温度的升高,会显著降低薄膜的残余应力,但对薄膜的硬度,摩擦系数没有明显影响.  相似文献   

4.
纳米反应多层膜是指两种或两种以上不同材料按一定厚度在衬底上交替沉积形成的薄膜材料。纳米反应多层膜是一种新结构形式的纳米含能材料,可在较低的能量刺激下发生放热反应,产生的热量足以使反应区以特定的速度自持传播,具有反应瞬间完成、放热量大等特点。由于结构可自行设计以及不同于单层膜的特殊性能,纳米反应多层膜可广泛应用于微电子器件、微机械系统(MEMS)等领域。对近年来国内外纳米反应多层膜的制备方法、反应机理以及在器件应用等方面的研究进行了综述,主要分析讨论了机械加工、蒸发镀膜和磁控溅射3种制备方法的优缺点,并对今后纳米反应多层膜的研究方向及研究重点进行了展望。  相似文献   

5.
采用"一锅法"和"热注入法"合成NiO纳米晶,研究了如何通过前躯体的选择和温度变化来调控NiO纳米晶的形貌和尺寸。采用"一锅法"时,若前驱体选用硬脂酸镍可得到单分散较好的近球形NiO纳米晶(2~5nm),若前驱体为四水乙酸镍时则可得到NiO纳米花(15~20nm)。采用"热注入法"时,控制前驱体和注入反应温度,可得到枝状纳米晶(5~10nm)和近球状纳米晶(30~40nm)。这是由于前躯体、温度和合成方法等因子影响晶体的总表面能、原子迁移和表面反应,因此,改变这些因素可以调节不同晶面的相对生长速度,从而调控NiO纳米晶的形貌和尺寸。  相似文献   

6.
直流电沉积法在Fe基体上制备Ni膜和在Cu基体上制备Ag膜,利用悬臂梁法在线测量了膜中的平均应力,并计算了膜内分布应力,且对膜内平均应力的实验结果与Thomas?Feimi?Dirac?Cheng(TFDC)电子模型理论估算结果进行了对比。结果表明,Fe基体上Ni膜的平均应力和分布应力均为拉应力,而Cu基体上Ag膜的平均应力和分布应力均为压应力。两种膜的内应力均由界面应力引起。对于相同的基体和镀膜,膜内平均内应力的理论估算值与实验值较接近。  相似文献   

7.
纳米超硬多层膜研究现状及发展趋势   总被引:1,自引:0,他引:1  
分别从溅射法和蒸发法两个方面评述了近年来纳米多层膜制备工艺的最新进展,在此基础上介绍了脉冲激光沉积(PLD)工艺制备纳米超硬多层膜的新方法.对典型的超硬膜TiN、(Ti,Zr)N、(Ti,Al)N、TiN/SiO2、B1-SiC、TiN/SiN4进行了简单回顾,并对其硬度、残余应力、摩擦磨损和抗氧化性能等方面做了详细的比较.最后,简述了纳米超硬多层膜表征的一般手段,并展望了发展前景.  相似文献   

8.
采用静电纺丝法和水热法,成功地制备了PA6/FexOy复合纳米纤维膜,并对其除铬性能进行了研究。红外光谱(FT-IR)、扫描电镜(SEM)、X-射线衍射(XRD)的表征结果显示:有分层结构的晶体氧化铁(FexOy)在PA6纳米纤维上生成。除铬实验结果表明:所制备的复合纳米纤维膜具有优良的除铬性能,最佳除铬温度是24℃,吸附过程是符合Freundlich等温吸附模型的多分子层吸附,吸附效果较好。因此,该研究为除去废水中六价铬提供了一种高效吸附剂,也为环境修复领域提供了一种了简单、高效的新方法。  相似文献   

9.
通过静电纺丝的方法制备了单轴取向的聚酰亚胺(PI)纳米纤维膜,并且采用不同环化温度的纳米纤维膜与聚酰亚胺基体进行复合,制备了一种PI纳米纤维增强PI复合薄膜。通过扫描电子显微镜(SEM)研究了纳米纤维的取向情况,以及纳米纤维膜与其基体的界面粘接情况;采用红外光谱对不同热处理温度PI纳米纤维膜的亚胺化程度进行了表征;并对复合薄膜的力学性能进行了表征。结果表明:通过提高滚筒转速可以得到高度取向结构的纳米纤维膜;纳米纤维膜的环化程度随热处理温度升高而提高;纳米纤维的亚胺化程度越低,其与基体之间的界面粘接性越好,复合薄膜的力学性能越佳。  相似文献   

10.
用基片曲率法测量薄膜应力   总被引:7,自引:0,他引:7  
安兵  张同俊  袁超  崔昆 《材料保护》2003,36(7):13-15
采用基片曲率法设计和制作了一种测量薄膜应力的装置,它具有简单、无损伤、快速、易于操作、精度高的优点。使用该装置测量了射频磁控溅射镀制的Cu单层膜和Ag/Cu多层膜的应力,结果表明薄膜残余应力是均匀的,但随沉积条件不同而不同。Cu单层膜和Ag/Cu多层膜处于压应力状态,外加-200V偏压时,Ag/Cu多层膜则转变为很小的拉应力状态。XRD表明Ag/Cu多层膜已结晶,呈现Ag(111)/Cu(111)择优取向。  相似文献   

11.
In this study we report an experimental approach capable of tuning dipolar interactions in hybrid magnetic nanofilms produced via layer-by-layer assembly of positively-charged maghemite nanoparticles and sodium sulfonated polystyrene onto glass and silicon substrates. Morphological and magnetic properties of the as prepared nanofilms were determined by Raman spectroscopy, atomic force microscopy, conventional and SQUID magnetometry. Maghemite nanoparticles form densely packed layers with voids between particles being filled by polymeric material as observed in atomic force microscopy images. Magnetic hysteresis loops and zero-field-cooled/field-cooled magnetization curves reveal a superparamagnetic behavior at room temperature. The energy barrier for the magnetic moment reversal of the nanofilms has been determined from the frequency dependent ac susceptibility and is related to the gamma-Fe2O3 nanoparticles concentration used in the colloidal dispersion throughout film fabrication. Variations on the interparticle distances have a direct effect on the interparticle dipolar interactions. A less concentrated colloid gives rise to large separated nanoparticles inside the nanofilm with a consequent reduction on the energy barrier for the magnetic moment reversal. The fabrication process exploring the control of the nanoparticle concentration can thus be used to tune the magnetic dipolar interactions in the nanofilms.  相似文献   

12.
Aspects of photothermal characterization of magnetoelectric nanofilms are presented. The parameters of the study include photomodulated surface reflectance and displacement of various nanostructures. A subsequent application is developed for assessment of film thickness by the use of optical absorption coefficient. The method refers to nanofilms deposited on transparent substrates, where the laser power is absorbed selectively in the film. The analytical approach is based on ultrasensitive laser double-heterodyne probe featuring resolution of thickness up to fractions of nanometre at improved translational resolution compared to ellipsometry.  相似文献   

13.
This paper described a novel physiologically compatible wafer bonding technique for bio-microelectromechanical systems (bio-MEMS) packaging. Room temperature bonding was performed between Parylene-C and silicon wafers with a thin Parylene-C coating using reactive Ni/Al nanofilms as localized heaters. Live NIH 3T3 mouse fibroblast cells were encapsulated in the package and they survived the bonding process owing to the localization of heating. A numerical model was developed to predict the temperature evolutions in the parylene layers, silicon wafer and the encapsulated liquid during the bonding process. The simulation results were in agreement with the cell encapsulation experiment revealing that localized heating occurred in this bonding approach. This study proved the feasibility of reactive nanofilm bonding technique for broad applications in packaging bio-MEMS and microfluidic systems.  相似文献   

14.
We use molecular dynamics simulations to investigate the thermal conductivity of argon-based nanofluid with copper nanoparticles through the Green-Kubo formalism. To describe the interaction between argon-argon atoms, we used the well-known Lennard-Jones (L-J) potential, while the copper–copper interactions are modeled using the embedded atom method (EAM) potential that takes the metallic bonding into account. The thermal conductivity of the pure argon liquid obtained in the present simulation agreed with available experimental results. In the case of nanofluid, our simulation predicted thermal conductivity values larger than those found by the existing analytical models, but in a good accordance with experimental results. This implies that our simulation is more adequate, to describe the thermal conductivity of nanofluids than the previous analytical models. The efficiency of nanofluids is improved and the thermal conductivity enhancement is appeared when the particle size and temperature increase.  相似文献   

15.
A method has been developed to stabilize and transfer nanofilms of functional organic semiconductors. The method is based on crosslinking of their topmost layers by low energy electron irradiation. The films can then be detached from their original substrates and subsequently deposited onto new solid or holey substrates retaining their structural integrity. Grazing incidence X‐ray diffraction, X‐ray specular reflectivity, and UV–Vis spectroscopy measurements reveal that the electron irradiation of ≈50 nm thick pentacene films results in crosslinking of their only topmost ≈5 nm (3–4 monolayers), whereas the deeper pentacene layers preserve their pristine crystallinity. The electronic performance of the transferred pentacene nanosheets in bottom contact field‐effect devices is studied and it is found that they are fully functional and demonstrate superior charge injection properties in comparison to the pentacene films directly grown on the contact structures by vapor deposition. The new approach paves the way to integration of the organic semiconductor nanofilms on substrates unfavorable for their direct growth as well as to their implementation in hybrid devices with unusual geometries, e.g., in devices incorporating free‐standing sheets.  相似文献   

16.
Size and shape dependencies of phase diagrams of the Ising nanofilms and nanotubes on the honeycomb lattice are investigated by means of probabilistic cellular automata simulation based on Glauber algorithm. The values of reduced critical temperature, K c = k B T c/J (where k B and J are the Boltzmann constant and nearest-neighbor coupling, respectively), for both nanofilms and nanotubes, are obtained at the different sizes of the lattices and the dependency of K c to the number of layers is studied. By increasing the number of layers K c increases but for number of layer more than 8, the critical temperature increases very slowly. We have shown that between two isotropic nanotubes with the same number of spins, the ones with greater diameter (more spins on the edge) have larger critical temperature. For equal size of lattices, the obtained values of K c for nanotube are greater than the nanofilm, but for large sizes, this difference disappears.  相似文献   

17.
Storm snow often avalanches before crystals metamorphose into faceted or rounded shapes, which typically occurs within a few days. We call such crystals nonpersistent, to distinguish them from snow crystals that persist within the snowpack for weeks or even months. Nonpersistent crystals can form weak layers or interfaces that are common sources of failure for avalanches. The anticrack fracture model emphasizes collapse and predicts that triggering is almost independent of slope angle, but this prediction has only been tested on persistent weak layers. In this study, dozens of stability tests show that both nonpersistent and persistent crystals collapse during failure, and that slope angle does not affect triggering (although slope angle determines whether collapse leads to an avalanche). Our findings suggest that avalanches in storm snow and persistent weak layers share the same failure mechanism described by the anticrack model, with collapse providing the fracture energy. Manual hardness measurements and near-infrared measurements of grain size sometimes showed thin weak layers of softer and larger crystals in storm snow, but often showed failures at interfaces marked by softer layers above and harder layers below. We suggest collapse often occurs in crystals at the bottom of the slab. Planar crystals such as sectored plates were often found in failure layers, suggesting they are especially prone to collapse.  相似文献   

18.
Surface engineering is a critical effort in defining substrates for cell culture and tissue engineering. In this context, multilayer self-assembly is an attractive method for creating novel composites with specialized chemical and physical properties that is currently drawing attention for potential application in this area. In this work, effects of thickness, surface roughness, and surface material of multilayer polymer nanofilms on the growth of rat aortic smooth muscle cells were studied. Polyelectrolyte multilayers (PEMs) electrostatically constructed from poly(allylamine hydrochloride) and poly(sodium 4-styrenesulfonate) (PSS) with gelatin, fibronectin, and PSS surface coatings were evaluated for interactions with smooth muscle cells (SMCs) in an in vitro environment. The results prove that PEMs terminated with cell-adhesive proteins promote the attachment and further growth of SMCs, and that this property is dependent upon the number of layers in the underlying multilayer film architecture. Cell roundness and number of pseudopodia were also influenced by the number of layers in the nanofilms. These findings are significant in that they demonstrate that both surface coatings and underlying architecture of nanofilms affect the morphology and growth of SMCs, which means additional degrees of freedom are available for design of biomaterials. This work supports the excellent potential of nanoassembled ultrathin films for biosurface engineering, and points to a novel perspective for controlling cell-material interaction that can lead to an elegant system for defining the extracellular in vitro environment.  相似文献   

19.
The elastic constants are calculated for a layered-silicate/polymer nanocomposite with intercalated morphology using the effective particle concept. Two continuum approaches are employed and compared: a 2D numerical strategy using the finite element method (FEM) and Monte-Carlo simulation of the morphology, and an analytical approach based on the orientation averaged Mori-Tanaka method.The particular contribution of this paper is to study systematically the concept of the effective particle, as an aid to more efficient FEM modelling, or more accurate analytical modelling of elastic constants for layered-silicate nanocomposites, with different degrees of intercalation. In particular, it is shown that the concept is successful, provided that full anisotropy of the effective particle is acknowledged. It is also demonstrated that the effect of anisotropy is particularly pronounced, when transverse or shear response of the nanocomposite is considered, even for fully aligned reinforcement. If the effective particles become misaligned, this effect diminishes (for transverse and shear properties), especially for fully random orientations of particles. Finally, it is shown that the effect of anisotropy is also pronounced, when the gallery material is softer than the surrounding polymer.  相似文献   

20.
This paper reports on measurements of in-plane thermal conductivities, electrical conductivities, and Lorentz number of two microfabricated, suspended, nanosized thin films with a thickness of 28 nm. The effect of the film thickness on the in-plane thermal conductivity is examined by measuring other nanofilm samples with a thickness of 40 nm. The experimental results show that the electrical conductivity, resistance–temperature coefficient, and in-plane thermal conductivity of the nanofilms are much smaller than the corresponding bulk values from 77 to 330 K. However, the Lorentz number of the nanofilms is about two times that of the bulk value at room temperature, and even up to three times that of the bulk value at 77 K. These results indicate that the relation between the thermal conductivity and electrical conductivity of the nanofilms does not follow the Wiedemann–Franz law for bulk metallic materials.  相似文献   

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