评估TiN薄膜与基材结合的划痕试验及有限元模拟

通过有限元模型模拟划痕试验得到的结果表明∶切应力的起伏变化?膜/基界面处切应力差值?接触区附近膜层表面张应力?高载下的几种应力集中等,对膜/基体系的失效都有重要的作用.通过模型计算临界载荷下的膜/基界面处切应力差值,可用来评价膜层与基材的结合强度;提出了划痕试验中膜/基体系失效的2种机制.不同性能基材的TiN膜/基体系划痕试验结果,可验证本文有限元模拟的有效性,并表明临界载荷是膜/基结合强度?体系承载能力?内聚结合性能等的综合反映;低载往复摩擦磨损试验的结果进一步证实,用划痕试验的临界载荷评估膜/基结合强度具有局限性.     

碳化硅薄膜的力学性能测试分析

对利用射频磁控溅射及真空退火方法在(100)硅晶片衬底上制备的纳米晶碳化硅(SiC)薄膜,用纳米压痕仪进行了力学性能测试分析。纳米压痕技术测试给出两块SiC薄膜样品I和II的弹性模量/硬度分别约为106GPa/9.5GPa和175GPa/15.6GPa。纳米划痕技术测试两块SiC薄膜的摩擦系数分别约为0.02~0.15和0.05~0.18,显示出良好的润滑性能;对薄膜的临界附着力等进行测量以评价膜基结合强度,分析了划痕过程中薄膜近表面弹塑性变形和断裂信息。在原子力显微镜下对SiC薄膜样品的初始表面及残余压痕和划痕形貌进行了观察分析,与测试结果相符。综合比较,样品II的整体性能优于样品I。本文中薄膜的弹性模量和硬度值较低可归因于制膜技术的不同和表层碳含量偏高。     

微纳米材料及其结构的界面强度的实验研究

介绍了近年来微纳米材料强度实验测试研究方面的最新进展,重点综述了可用于微纳米材料及其结构中界面强度测试的实验系统、测试方法及结果.主要内容包括:测试微纳米薄膜界面端分层裂纹启裂的夹层悬臂梁方法,测试纳米岛/衬底间界面结合强度的改进AFM (atomic force microscopy)方法, 测试裂纹沿界面扩展的预裂纹法,可实现纳米薄膜界面裂纹原位观察的实验测试方法,测试薄膜在疲劳、蠕变条件下界面裂纹扩展的改进4点弯曲法等.除了总结分析测试结果,还讨论了上述实验方法的优缺点和适用范围,并指出了微纳米材料界面强度实验研究方面的一些挑战与难点,最后提出了若干需要继续研究的课题.      

Cr/Ag纳米多层薄膜膜-基结合强度及摩擦学性能研究

采用中频磁控溅射技术在AISI 440C钢表面制备了不同调制周期的Cr/Ag纳米多层薄膜.通过X射线衍射仪（XRD）及高分辨透射电子显微镜（HRTEM）分析表征了纳米多层薄膜的微观组织结构,通过划痕试验机与真空球-盘摩擦试验机分别测试了纳米多层薄膜膜-基结合强度及真空摩擦学性能,并与纯Ag薄膜及Cr/Ag双层薄膜进行了对比.结果表明：纳米多层结构可以显著提高Ag基固体润滑薄膜膜-基结合强度,Cr/Ag纳米多层薄膜在较高转速及载荷条件下表现出明显优于纯Ag及Cr/Ag双层薄膜的摩擦学性能.Cr薄膜层与钢基体表面良好结合以及纳米多层薄膜内良好的层间结合性能是纳米多层薄膜膜-基结合强度提高的主要原因.     

CM—I形多功能擦膜摩擦试验机的研制（I）—原理与构成

评价膜－基体系的综合性能的重要指标是其失效的临界载荷。膜－基体系的失效不仅发生在界面，也有可能发生在镀层或底材之中，或许还有可能发生混合失效，因此，在测试膜－基低系失效的临界载荷方面，即使是已经在国内外得到广泛应用的划痕法也有其弱点，为了使膜－基体系的失效临界载荷的测试尽可能地接近于实际使用工况，更能切近实际地反映膜－基体系的综合承载能力，提出了一种擦膜试验法，并且研制了ＣＭ－１型多功能擦膜摩擦试     

空间薄膜阵面结构褶皱的实验研究

阵面薄膜上的褶皱会显著影响航天器性能,褶皱控制也是薄膜航天器研发的难点。本文采用白光扫描技术,测试了一个正方形薄膜阵面结构在纯剪切作用下的褶皱特性。测试结果显示,随着剪切力的增大,结构膜面褶皱数增加,褶皱幅度增大,膜面平整度降低。随着膜面预应力的增大,膜面上的褶皱数略有增大,褶皱幅度有所减小,膜面平整度有所提高。测试结果还显示,膜面上粘结缝的存在、以及粘结缝与剪切力间的方位关系对膜面褶皱有复杂的影响。论文所得结论对薄膜阵面结构设计研发具有参考价值。     

CM－Ⅰ型多功能擦膜摩擦试验机的研制（Ⅰ）─—原理与构成

评价膜－基体系的综合性能的重要指标是其失效的临界载荷。膜－基体系的失效不仅发生在界面，也有可能发生在镀层或底材之中，或许还有可能发生混合失效，因此，在测试膜－基体系失效的临界载荷方面，即使是已经在国内外得到广泛应用的划痕法也有其弱点，为了使膜－基体系的失效临界载荷的测试尽可能地接近于实际使用工况，更能切近实际地反映膜－基体系的综合承载能力，提出了一种擦膜试验法，并且研制了ＣＭ－Ⅰ型多功能擦膜摩擦试验机，同时还着重就这种试验机的测试原理、构成和标定作了阐述，并对试验机的主要技术参数及其功能与特点作了介绍，为评价和研究膜－基体系的摩擦学特性、失效及综合承载能力提供了一种新手段。     

薄膜涂层材料界面纯剪破坏标准试验法的开发

界面强度是薄膜涂层材料的最重要的性能指标之一，目前尚缺乏有效的测量方法。测量界面强度的主要困难在于寻求一种便于试验的试件形状和加载方式，使得界面上能够产生不同的应力状态，即在不同的剥离应力和剪应力比的状态下发生破坏。本文采用有限元数值分析（ABAQUS），研究了几种具有简单几何形状的试件的界面应力，并基于大量的数值试验，设计了剪应力为破坏支配因素的试件形状和加载方式，并且给出了便于应用的最大界面剪应力的经验估算公式。该经验公式可以适用于各种材料组合和薄膜涂层的厚度。研究结果表明，通过对薄膜涂层材料试件的基体引入缺口以产生应力集中，进行普通的四点弯曲试验，可以进行剪应力占支配地位的界面破坏试验。利用本文提出的试件形状和相应的最大界面剪应力经验公式，可以通过破坏试验简单地得到界面的剪切强度。     

涂层/基体材料界面结合强度测量方法的现状与展望

界面结合强度是涂层/基体材料体系中的一项重要力学性能指标.而表征与评价涂层/基体材料的界面结合强度又得依靠实验 方法的测定.由于涂层/基体材料体系的多样性与复杂性, 至今还没有形成适合于测量这类材料的界面结合强度的标准方法. 目前, 常用来测量涂层/基体材料的界面结合强度的方法有：拉伸法、剪切法、弯曲法、划痕法、压入法等.本文就目前表征 与评价涂层/基体材料界面结合强度的测量方法做了综述, 讨论了它们的适用范围, 比较了它们的优势与不足.     

磁过滤多弧离子镀C/C多层膜在模拟体液中的微磨粒磨损行为

采用磁过滤直流阴极真空弧源沉积技术在Ti6Al4V表面制备C/C多层DLC膜,利用纳米压痕划痕仪测试薄膜的纳米硬度和膜-基结合强度,采用微磨粒磨损试验机对C/C多层DLC膜在模拟体液环境中的磨损性能进行评价,并与Ti6Al4V的耐磨性能进行对比.结果表明:C/C多层DLC膜硬度达54.82 GPa,弹性模量和划痕临界载荷分别为342.27 GPa和0.52 N;在模拟体液环境中DLC膜的耐磨性能显著优于Ti6Al4V合金,DLC膜的磨损机制主要包括二体磨损及混合磨损;随着料浆浓度的增加,DLC膜的磨损机制从二体磨损向混合磨损过渡.     

Characterization of the fracture work for ductile film undergoing the micro-scratch

The interface adhesion strength (or interface toughness) of a thin film/substrate system is often assessed by the micro-scratch test. For a brittle film material, the interface adhesion strength is easily obtained through measuring the scratch driving forces. However, to measure the interface adhesion strength (or interface toughness) for a metal thin film material (the ductile material) by the micro-scratch test is very difficult, because intense plastic deformation is involved and the problem is a three-dimensional elastic-plastic one. In the present research, using a double-cohesive zone model, the failure characteristics of the thin film/substrate system can be described and further simulated. For a steady-state scratching process, a three-dimensional elastic-plastic finite element method based on the double cohesive zone model is developed and adopted, and the steady-state fracture work of the total system is calculated. The parameter relations between the horizontal driving forces (or energy release rate of the scratching process) and the separation strength of thin film/substrate interface, and the material shear strength, as well as the material parameters are developed. Furthermore, a scratch experiment for the Al/Si film/substrate system is carried out and the failure mechanisms are explored. Finally, the prediction results are applied to a scratch experiment for the Pt/NiO material system given in the literature. The project supported by the National Natural Science Foundation of China (19891180 and 19925211) and Bai Ren Plan of CAS     

Molecular dynamics investigation of patterning via cold welding

We perform a series of molecular dynamics simulations of a subtractive cold-welding patterning process. The effects of film thickness and work of adhesion between the thin film and substrate are examined. For small works of adhesion, the film elastically debonds from the substrate before the onset of plastic deformation inside the film during stamp retraction. A simple model is proposed to describe the debonding and deformation of the film. The model provides an analytical framework that describes the playoff between adhesion, yield strength, and film thickness in determining the debond length of the film induced by stamp retraction.     

Distribution of dislocation source length and the size dependent yield strength in freestanding thin films

A method is proposed to estimate the size-dependent yield strength of columnar-grained freestanding thin films. The estimate relies on assuming a distribution of the size of Frank-Read sources, which is then translated into a log-normal distribution of the source strength, depending on film thickness, grain size and theoretical strength of the material, augmented with a single fit parameter. Two-dimensional discrete dislocation plasticity (DDP) simulations are carried out for two sets of Cu films and the fit parameter is determined from independent experiments. Subsequent DDP predictions of the stress-strain curves in comparison with the corresponding experimental data show excellent agreement of initial yield strength and hardening rate for films of varying film thickness and grain size. Having thus demonstrated the power of the proposed strength distribution, it is shown that the mode of this distribution governs the most effective source strength. This is then used to suggest a method to estimate the yield strength of thin films as a function of film thickness and grain size. Simple maps are presented that are in very good agreement with recent experimental results for Cu thin films.     

Indentation tests investigation of mechanical behavior of two-dimensional materials

准确了解二维材料的力学性能对于推动其应用具有重要意义, 无基底压痕技术是目前最广泛采用的二维材料力学性能测试方法之一, 本文综述了二维材料压痕研究的最新进展以及所面临的问题, 并对将来的研究工作进行了展望.无基底压痕技术是将二维材料转移到带有沟槽或柱形孔的基底上, 制备二维材料"梁"和"鼓"模型, 然后利用原子力显微镜测量其在压针作用下的载荷--位移关系, 最后通过基于连续介质薄膜导出的压痕响应分析模型拟合实验结果, 估算出二维材料的弹性模量和本征强度.由于二维材料的厚度远小于连续介质薄膜, 来自于压头以及基底孔侧壁的范德华力对二维材料的压痕响应具有显著影响, 造成二维材料与传统压痕分析模型中的基本假设不符, 导致不能准确预测二维材料的弹性模量; 另外, 由于传统压痕模型无法准确描述二维材料在大变形下的非线性行为, 以及由缺陷等引起的应力集中, 导致由压痕测试表征的二维材料(特别是多晶二维材料)本征强度具有较大的偏差. 因此, 一方面需要正确了解由压痕技术获得的二维材料力学性能, 另一方面还需对目前的研究方法做进一步的改进和完善.     

二维材料力学行为的压痕测试

准确了解二维材料的力学性能对于推动其应用具有重要意义, 无基底压痕技术是目前最广泛采用的二维材料力学性能测试方法之一, 本文综述了二维材料压痕研究的最新进展以及所面临的问题, 并对将来的研究工作进行了展望.无基底压痕技术是将二维材料转移到带有沟槽或柱形孔的基底上, 制备二维材料"梁"和"鼓"模型, 然后利用原子力显微镜测量其在压针作用下的载荷--位移关系, 最后通过基于连续介质薄膜导出的压痕响应分析模型拟合实验结果, 估算出二维材料的弹性模量和本征强度.由于二维材料的厚度远小于连续介质薄膜, 来自于压头以及基底孔侧壁的范德华力对二维材料的压痕响应具有显著影响, 造成二维材料与传统压痕分析模型中的基本假设不符, 导致不能准确预测二维材料的弹性模量; 另外, 由于传统压痕模型无法准确描述二维材料在大变形下的非线性行为, 以及由缺陷等引起的应力集中, 导致由压痕测试表征的二维材料(特别是多晶二维材料)本征强度具有较大的偏差. 因此, 一方面需要正确了解由压痕技术获得的二维材料力学性能, 另一方面还需对目前的研究方法做进一步的改进和完善.      

Experimental-Theoretical Approach to Determining the Film–Substrate Adhesion

There are well-known methods and algorithms for determining the film adhesion to a plane substrate, which have their own advantages and drawbacks and the applicability ranges. The substrates can have a good initial shape (spherical, cylindrical, etc,) covered, for example, by a thin film layer. But there are practically no studies of the film adhesion to a substrate with a nonplane surface. A two-dimensional approach to determining the film adhesion to a plane or a nonplane substate is developed, which permits increasing the accuracy of determining the adhesion and decreasing the scattering of the obtained results. An example is considered.     

磁场力及膜曲率对磁敏感薄膜-基底界面 黏附性能的影响与调控

界面黏附和脱黏的可调控在攀爬装置、黏附开关、机械抓手等方面具有重要的应用需求. 针对磁敏感薄膜-基底界面, 开展了薄膜初始曲率及外加磁场对界面黏附性能影响机制的研究. 首先实验制备了具有初始曲率的磁敏感薄膜, 分别开展了具有初始曲率的磁敏感薄膜-基底界面撕脱实验及理论研究, 研究了薄膜初始曲率、弯曲刚度和外加磁场强度对界面黏附性能的影响规律. 实验和理论结果一致表明: 具有初始曲率的磁敏感薄膜-基底界面黏附力随薄膜初始曲率的增大而减小, 而外加磁场能够有效提高界面黏附力;相比于初始零曲率薄膜-基底界面稳态撕脱力与薄膜弯曲刚度无关, 薄膜弯曲刚度减弱了具有初始曲率薄膜-基底界面的稳态撕脱力. 进一步从能量角度分析了界面等效黏附性能, 揭示了薄膜弯曲能、磁场势能、界面黏附能的相互竞争机制. 最后, 基于本文的实验及理论结果, 提出了一种磁场和薄膜初始曲率协同调控的简易机械抓手, 可连续实现物体的拾取、搬运和释放功能. 本文结果不仅有助于理解多场调控的界面可逆黏附机制, 对界面黏附可控的功能器件设计亦提供了一种新方法.      

A new method for manufacture of thin film heat flux gauges

The manufacture of thin film gauges for measuring transient temperatures and heat fluxes is described. A new method of using ceramic substrates (ZrO₂) with two sintered platinum wires is described. Examples of static and dynamic calibrations are given. Sample measurements in a shock tunnel are presented. The gauges show good mechanical strength and sensitivity.This article was processed using Springer- Verlag T_EX Shock Waves macro package 1990.     

离子注入对SiO2表面非晶碳薄膜的化学状态及摩擦学性能的影响

采用真空蒸镀法在SiO     

The effect of water diffusion on the adhesion of organosilicate glass film stacks

Organosilicate glass (OSG) is a material that is used as a dielectric in advanced integrated circuits. It has a network structure similar to that of amorphous silica where a fraction of the Si-O bonds have been replaced by organic groups. It is well known from prior work that OSG is sensitive to subcritical crack growth as water molecules in the environment are transported to the crack tip and assist in rupturing Si-O bonds at the crack tip. In this study, we demonstrate that exposure of an OSG containing film stack to water prior to fracture results in degradation of the adhesion of the film stack. This degradation is the result of the diffusion of water into the film stack. We propose a quantitative model to predict adhesion degradation as a function of exposure time by coupling the results of independent subcritical crack growth measurements with diffusion concentration profiles. The model agrees well with experimental data and provides a novel method for measuring the water diffusion coefficient in film stacks that contain OSG. This study has important implications for the reliability of advanced integrated circuits.