100nm厚铜薄膜的拉伸性能

以聚酰亚胺为基体制备了厚度为100nm的金属铜薄膜,利用基体的高弹性变形测定了铜薄膜的屈服应力,并研究了铜薄膜的形变与断裂行为．结果表明：使用铜薄膜／聚酰亚胺复合体能够测量出铜薄膜的屈服强度,厚度100nm的铜薄膜的屈服强度明显高于厚铜膜的屈服强度,厚度100nm铜薄膜的断裂为Ⅰ型沿晶断裂．超薄铜薄膜较高的屈服强度归因于小尺度材料中纳米量级的薄膜厚度和晶粒对位错运动的约束作用．     

考虑压-拉薄膜效应的围框约束RC板极限抗力分

合理估算大变形条件下梁板构件的极限抗力,对工程设计计算具有重要意义。传统的RC （reinforced concrete）板极限抗力一般由小变形条件下的受压薄膜效应得到,然而RC板构件的灾变断裂大部分出现在大挠度阶段,因此考虑压-拉薄膜效应的极限抗力分析尤为重要。该文将RC板从加载到断裂全过程分为板端受压上升段、混凝土开裂下降段和钢筋拉伸上升段,根据正截面抗弯的钢筋混凝土弹塑性模型得到基于受压薄膜效应的荷载-挠度全曲线。利用经典的挠曲线微分方程并引入抗弯刚度软化系数对挠度进行修正,结合能量原理推导出大变形条件下基于受拉薄膜效应的RC板极限抗力,进一步得到考虑压-拉薄膜效应的荷载-挠度全曲线。计算结果表明,考虑压-拉薄膜效应的RC板极限抗力分析方法可以更合理地预测荷载-挠度全过程,计算结果与相关试验吻合良好,为合理评估RC板的极限承载力提供参考。     

考虑压-拉薄膜效应的围框约束RC板极限抗力分析

合理估算大变形条件下梁板构件的极限抗力,对工程设计计算具有重要意义。传统的RC(reinforced concrete)板极限抗力一般由小变形条件下的受压薄膜效应得到,然而RC板构件的灾变断裂大部分出现在大挠度阶段,因此考虑压-拉薄膜效应的极限抗力分析尤为重要。该文将RC板从加载到断裂全过程分为板端受压上升段、混凝土开裂下降段和钢筋拉伸上升段,根据正截面抗弯的钢筋混凝土弹塑性模型得到基于受压薄膜效应的荷载-挠度全曲线。利用经典的挠曲线微分方程并引入抗弯刚度软化系数对挠度进行修正,结合能量原理推导出大变形条件下基于受拉薄膜效应的RC板极限抗力,进一步得到考虑压-拉薄膜效应的荷载-挠度全曲线。计算结果表明,考虑压-拉薄膜效应的RC板极限抗力分析方法可以更合理地预测荷载-挠度全过程,计算结果与相关试验吻合良好,为合理评估RC板的极限承载力提供参考。     

考虑受拉薄膜效应的板块平衡法修正及在混凝土双向板中的应用

经典塑性铰线理论中的板块平衡法无法考虑钢筋混凝土板在大变形时产生的受拉薄膜效应的影响。为解决这一问题,该文提出了一种可以考虑受拉薄膜效应的修正板块平衡法。该方法将钢筋混凝土板的受力行为分为屈服前和屈服后两个阶段。假设钢筋混凝土板在屈服前的变形为弹性,分别采用Navier法和板块平衡法确定板的屈服挠度和屈服承载力。为考虑屈服后钢筋混凝土板中产生的受拉薄膜效应,假设板底塑性铰线截面上钢筋的竖向分力为产生受拉薄膜效应的主要原因,而钢筋的水平分力则与截面上混凝土的压力组成力偶构成了钢筋混凝土板的截面抵抗弯矩。通过上述修正,可以获得由考虑受拉薄膜效应的修正板块平衡法计算的钢筋混凝土板的全过程荷载-挠度曲线。为验证该文方法,对大挠度足尺混凝土双向板进行了应用研究。通过对比可知,理论分析结果与试验结果较为接近,从而验证了修正板块平衡法的有效性。     

含Ni夹杂的纳米晶Cu基体力学性能分子动力学模拟

通过拉伸加载的方式研究以Cu为基体、Ni为夹杂的Cu/Ni纳米晶薄膜的力学性能,以及夹杂尺寸、形状对薄膜屈服强度的影响。基于原子嵌入势函数,运用分子动力学方法分析夹杂与位错的相互作用。结果表明:Ni夹杂的引入降低了材料的屈服强度;而在塑性变形阶段依靠界面及Ni原子间较强的相互作用力,夹杂能够阻碍位错的传播,起到强化作用。对于正方形、横置矩形、圆形和竖置矩形的夹杂,当横截面积为6.9nm~2时,薄膜的屈服强度接近;当横截面积为15.7nm~2时,含横置矩形夹杂的薄膜具有最大屈服强度,为7.41MPa;当横截面积为3.1nm~2时,含圆形夹杂的薄膜具有最大屈服强度,为6.93MPa。     

功能梯度蜂窝材料的面内冲击性能研究

根据功能梯度特性的概念,建立了具有递变屈服强度梯度特性的圆形蜂窝结构数值仿真模型。在此模型的基础上详细讨论了递变屈服强度梯度和冲击速度对圆形蜂窝材料面内冲击性能的影响。研究结果表明递变梯度值对蜂窝结构的变形模式有较大影响。通过合理地选择蜂窝结构的递变屈服强度梯度值,进入被保护结构的应力值明显降低,蜂窝材料的能量吸收能力也得到有效控制。该结果能为完善屈服强度梯度蜂窝材料的研究和设计提供理论指导。     

微机械悬桥法研究氮化硅薄膜力学性能

利用高精密纳米压入仪检测微机械悬桥的载荷-挠度曲线,来研究低应力LPCVD氮化硅薄膜的力学特性。通过大挠度理论分析,得到考虑了衬底变形对挠度有贡献的微桥挠度解析表达式。对于在加卸载过程中表现出完全弹性的微桥,利用最小二乘法对其挠度进行了拟合,从而得到杨氏模量、残余应力和弯曲强度等力学特性参数。低应力LPCVD氮化硅薄膜的研究结果:杨氏模量为(308.4±24.1)GPa,残余应力为(252.9±32.4)MPa,弯曲强度为(6.2±1.3)GPa。     

润滑薄膜测量的双色光干涉强度调制技术

光干涉技术是润滑薄膜厚度测量最有效的方法之一。双色光干涉法在保证较大膜厚测量范围及高测量分辨力的同时,避免了繁琐的干涉级次人工计数。传统的双色光干涉测量依赖于严格的静态标定和观测者。本文提出使用双色光干涉强度调制技术对微纳米润滑薄膜进行测量。通过干涉图像中红、绿分量强度值的线性叠加得到调制信号,根据信号特性分析得到特征位置膜厚,进而由干涉强度得到任一点膜厚。为验证所提出测量方法的正确,对静态球-盘赫兹接触表面间隙进行了测量,与经典理论有很好的一致性。结果表明:选用合适的红绿双色光波长,测量量程可达2μm。     

薄膜结合强度的刮剥式测量方法

本文介绍了一种薄膜结合强度的新型测量方法～刮剥法的测量原理、特点以及应用范围。所谓薄膜结合强度的刮剥式测量方法（简称刮剥法），实际上是一个使用特制刮剥刀具、以类似于薄层金属刮削方式工作，并以从基底上剥离薄膜所需能量作为其结合强度量度的测量方法。刮剥法与现广泛使用的划痕式结合力测量法的区别主要表现为：（１）该法是一个能量测量方法，即以薄膜的剥离能量作为薄膜与基体的结合强度的描述；（２）测量时采用的是对膜／基界面的切向加载方式；（３）测量结果是对膜／基结合强度的直接描述，并对基底表面状态、材质等不敏感；（４）可以对其它方法无法进行测量的超硬材料薄膜，如金刚石和立方氮化硼等，进行结合强度测量。本文通过对刮剥过程中刮剥刀刃附近区域的受力分析，得出了成功实现沿界面剥离薄膜的必要条件以及刮剥法测试对试样的要求和应用范围。     

爆炸冲击波参数薄膜测试法研究

为可靠获取爆炸冲击波超压参数,设计一种铝箔薄膜结构进行实验。通过控制材料状态、结构频率特性等参数,使其满足一定毁伤准则,建立力学模型对其进行分析。利用激波管装置对薄膜变形进行标定,并将激波反射载荷转换为入射压,采用最小二乘法进行线性拟合,得到薄膜最大变形挠度与激波入射压峰值之间关系。结果表明,可通过铝箔薄膜最大变形挠度反映爆炸场中0.05~0.35 MPa范围内的入射冲击波超压,为冲击波测试工程应用提供新的途径。     

平头压痕试验确定薄膜弹塑性参数的研究

本文研究用平头压痕试验确定薄膜-基体材料中薄膜材料弹塑性参数的可行性,重点研究了薄膜材料的屈服强度和硬化模量的确定方法.利用有限元(FEM)进行了模拟计算,给出了平头压痕下典型的等应力分布,以及载荷-压入深度的曲线.通过对载荷-压入深度曲线的研究,给出了通过平头压痕试验确定薄膜屈服强度和薄膜硬化模量的方法.     

Magnetically actuated peel test for thin films

Delamination along thin film interfaces is a prevalent failure mechanism in microelectronic, photonic, microelectromechanical systems, and other engineering applications. Current interfacial fracture test techniques specific to thin films are limited by either sophisticated mechanical fixturing, physical contact near the crack tip, or complicated stress fields. Moreover, these techniques are generally not suitable for investigating fatigue crack propagation under cyclical loading. Thus, a fixtureless and noncontact experimental test technique with potential for fatigue loading is proposed and implemented to study interfacial fracture toughness for thin film systems. The proposed test incorporates permanent magnets surface mounted onto micro-fabricated released thin film structures. An applied external magnetic field induces noncontact loading to initiate delamination along the interface between the thin film and underlying substrate. Characterization of the critical peel force and peel angle is accomplished through in situ deflection measurements, from which the fracture toughness can be inferred. The test method was used to obtain interfacial fracture strength of 0.8-1.9 J/m² for 1.5-1.7 μm electroplated copper on natively oxidized silicon substrates.     

Adhesion and vacuum forming properties of tin-zinc thin films deposited on polyester film substrate

Sn-Zn alloy thin films were deposited on a polyester (PET) film substrate by co-evaporation and evaluated their surface, tensile and adhesion properties with a vacuum forming test and pull test.Relationship between the surface roughness and elemental composition of these thin films was evaluated. The surface roughness decreased with increase of the Sn content.The tensile property was estimated by observations of micro-cracks of the thin films due to a vacuum forming test. Sn-Zn alloy thin film, whose elemental composition is 85:15 (wt%), had high vacuum forming durability.The adhesion strength between the Sn-Zn alloy thin films and PET substrate was measured with a pull test apparatus. The pull strength decreased with increase of the Sn content.     

A comparative micro-cantilever study of the mechanical behavior of silicon based passivation films

A comprehensive study on the mechanical behavior of plasma enhanced chemical vapor deposited silicon oxide, oxynitride and nitride thin films is provided. Hardness, Young's modulus, yield stress, fracture stress and fracture toughness values are determined by the nanoindentation and the micro-cantilever deflection technique. The micro-cantilever deflection technique is discussed in terms of measurement accuracy and reproducibility and the results are compared with standard nanoindentation measurements. Correlations between the yield and fracture behavior, which have been observed for glass fibers, are discussed in this paper for dielectric thin film glasses.     

Synthesis of nickel picrate energetic film in a 3D ordered silicon microchannel plate through an in situ chemical reaction

Micro-energetic devices with energetic and functional diversity have attracted interest from scientific communities, through features such as the integration of energetic materials into micro-electro-mechanical systems (MEMS). In this study, a method for the preparation of nickel picrate energetic films on the sidewalls of a silicon microchannel plate (Si-MCP) is presented. The Si-MCP was produced by a photoelectrochemical process and a thin film of nickel (Ni) was synthesized by electroless plating of Ni on the sidewalls of the Si-MCP. The thin film of nickel picrate was successfully produced via an in situ chemical reaction method by introducing picric acid into the 3D ordered nickel/silicon microchannel plate (Ni/Si-MCP). Field emission scanning electron microscopy, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy were used to study the morphological and structural properties of the thin film. The results demonstrate that picric acid reacted with Ni to form a nickel picrate thin film. Also, differential scanning calorimetry and thermogravimetric analysis were employed to characterize the thermal decomposition of the energetic film. The approach can solve the problem of integrating organic energetic materials with MEMS devices. Also, nickel picrate can release a mass of energy and gas simultaneously, which further enhances the functional diversity of MEMS devices.     

氮化硅介质薄膜内应力的实验研究

研究了等离子体增强化学气相沉积氮化硅介质薄膜的内应力。采用钠光平面干涉测量了氮化硅薄膜内应力,通过改变薄膜沉积时的工艺参数,考察了反应气体流量比、沉积温度、射频功率密度等因素对氮化硅薄膜内应力的影响。在此基础上,对氮化硅介质薄膜本征应力的形成机制进行了分析讨论。     

Preparation and characterization of metalorganic chemical vapor deposited nickel oxide and lithium nickel oxide thin films

Thin films of nickel oxide and lithium nickel oxide were deposited through the pyrolysis of nickel acetylacetonate and lithium nickel acetylacetonate, respectively in the temperature range 350–420 °C. The single solid source precursors, nickel acetylacetonate and lithium nickel acetylacetonate were prepared and characterized using Energy Dispersive X-Ray Fluorescence (EDXRF), X-Ray Diffraction (XRD) and infrared spectroscopy. The composition, optical and electrical properties of the prepared thin films were analysed using a variety of techniques, including, Rutherford Backscattering Spectroscopy (RBS), EDXRF, XRD, UV–Visible Spectrophotometry and van der Pauw conductivity method. The amount of metals in the prepared thin films did not reflect the ratio of the metals in the precursor but was found to depend on the deposition temperature. The energy gaps of the nickel oxide and lithium nickel oxide thin films are 3.7 and 3.2 eV, respectively. The electrical conductivity showed that lithium nickel oxide thin film has an activation energy of 0.11 eV. The conduction was explained by a hopping mechanism.     

The measurement of thin film stress using phase shifting interferometry

Abstract

A new technique for determining the stress of thin films is described. This technique combines digital phase shifting interferometry with image-processing software. A circular disc polished on one side is used as the coated substrate during film deposition. The average stress in thin films can be derived by comparing the deflection of the substrate before and after film deposition. The deflection of the substrate by the deposited film is obtained by the phase map. Using the Zernike polynomial fitting algorithm, a three-dimensional contour map is generated from the polynomial coefficients to visualize the deformation of the thin film and to examine the tensile or compressive stress after film deposition. Four oxide films prepared by ionbeam sputter deposition are investigated for their film stresses. The experimental results show that the stress values are concordant with measurements using other methods.     

Theoretical Modeling of Obliquely Crossed Photothermal Deflection for Thermal Conductivity Measurements of Thin Films

A three-dimensional theoretical model has been developed to calculate the normal probe beam deflection of the obliquely crossed photothermal deflection configuration in samples which consist of thin films deposited on substrates. Utilizing the dependence of the normal component of probe beam deflection on the cross-point position of the excitation and probe beams, the thermal conductivity of the thin film can be extracted from the ratio of the two maxima of the normal deflection amplitude, which occurs when the cross-point is located near both surfaces of the sample. The effects of other parameters, including the intersect angle between the excitation and the probe beams in the sample, the modulation frequency of the excitation beam, the optical absorption and thickness of the thin films, and the thermal properties of substrates on the thermal conductivity measurement of the thin film, are discussed. The obliquely crossed photothermal deflection technique seems to be well suited for thermal conductivity measurements of thin films with a high thermal conductivity but a low optical absorption, such as diamond and diamond-like carbon, deposited on substrates with a relatively low thermal conductivity.     

A structural comparison of electroless and electroplated nickel

Nickel that has been electrolessly deposited from a low temperature hypophosphite bath undergoes severe cracking when heat treated. The cracks, which are of two different types, can weaken the nickel deposit and can lead to leak paths in composite structures. In the study reported here the characteristics of thin nickel films were studied by several methods, all of which can be applied to any crystalline thin film: an X-ray method for stress and precipitation sequences; electron microscopy; cross-sectional analysis; kinetic studies. The electroless nickel was compared with a low stress electroplated nickel which does not crack with heat treatment. The electroplated nickel was found not only to have lower stress than the electroless nickel but also to have no significant secondary phase precipitation.