类金刚石碳膜的纳米划擦行为及其加载—卸载效应

用射频等离子体增强化学气相沉积方法在硅片上制备了类金刚石碳膜,利用纳米压入仪的是痕附件研究了薄膜的纳米划擦行为,结果表明：在划擦过程中,随载荷增加,薄膜先后经历弹性变形、弹塑性变形,加载开裂及卸载剥离三个阶段,在连续加载直至薄膜开裂的过程中薄膜未发生剥落,卸载的薄膜与基体变形恢复不同步,发生薄膜从基体上的脆性剥落,纳米划擦实验不仅能在加载阶段获得表征薄膜内聚强度的临界载荷,而且能检测卸载过程中薄膜附着抗力有关的临界载荷,是评价类金刚石薄膜划擦抗力的有效手段之一。     

钛合金表面微弧氧化膜的特点及成膜分析

用微弧氧化方法在钛合金上形成二氧化钛薄膜，用扫描电镜、X射线衍射以及透射电镜分析了膜的组织结构和化学成分，用纳米压入仪和划擦仪测量了膜的硬度和弹性模量及划擦抗力。结果表明，钛合金表面形成一层微弧氧化膜，含有纳米晶结构。薄膜由晶体和少量非晶体组成，硬度和弹性模量分别为0．78GPa和35．6GPa，划擦过程中未出现膜从基体表面的剥落，但高载荷下膜本身有破坏和脱落。     

钨合金超声辅助划擦试验及仿真研究

目的 揭示钨合金在超声辅助磨削加工下的材料去除行为。方法 通过超声辅助划擦试验与有限元仿真相结合的方式,分析超声振动作用对材料表面形貌、截面轮廓、划擦力、温度、塑性应变及应变率的影响,探究超声振动作用下的材料去除和表面创成机理。结果 钨合金在划擦过程中发生严重的塑性变形,在划痕两侧出现由耕犁作用而形成的隆起现象。超声辅助划擦形成的划痕表面鳞刺更少且未出现犁沟现象,且划痕深度相较于普通划擦增大14.1%,划痕宽度增大39%。随着划擦深度的增加,试验划擦力与仿真划擦力均线性增大,且仿真值与试验值误差为18.1%,验证了有限元仿真模型的有效性。超声振动作用下的划擦力呈周期性变化特征,使平均划擦力降低了43.2%。此外,仿真结果表明,超声辅助划擦相较于普通划擦,温度最高降低50%,表面塑性应变最高降低20%,超声冲击过程中材料的塑性应变率相较于普通划擦提高1个数量级,分离过程中塑性应变率最大降低2个数量级。结论 超声振动作用可以有效降低划擦过程中的划擦力和划擦区域温度,增大冲击过程中材料的瞬时应变率,改善压头的切屑黏附现象,从而抑制划擦表面鳞刺的生成和犁沟的形成,改善表面质量。此外,超声振动作...     

Scratch Behavior, Microstructure, Resistivity and Optical Properties of Indium Tin Oxide Film Grown at Low Deposition Temperature

通过RF磁控溅射技术制备不同溅射气压下的ITO薄膜,对其电阻率、光学透过率、XRD图、AFM图和划擦行为进行了研究。薄膜和基板的附着力通过划擦测试进行表征,重点研究了薄膜划擦测试的不同阶段的特征。研究表明随着Ar溅射气压的下降,薄膜附着力下降。而且,ITO薄膜的表面形貌和电阻率强烈的依赖于Ar气压。低温沉积ITO薄膜均为非晶态,在溅射气压0.8 Pa时得到电阻率(1.25×10-3 Ω×cm)和高可见光透过率薄膜(90%)。研究结果表明该薄膜光学禁带约为3.85 eV,电阻率主要受载流子浓度控制,受溅射气压的变化影响有限。     

低温沉积ITO薄膜划擦行为、微结构、电学和光学性能的研究（英文）

通过RF磁控溅射技术制备不同溅射气压下的ITO薄膜,对其电阻率、光学透过率、XRD图、AFM图和划擦行为进行了研究。薄膜和基板的附着力通过划擦测试进行表征,重点研究了薄膜划擦测试的不同阶段的特征。研究表明随着Ar溅射气压的下降,薄膜附着力下降。而且,ITO薄膜的表面形貌和电阻率强烈的依赖于Ar气压。低温沉积ITO薄膜均为非晶态,在溅射气压0.8 Pa时得到电阻率(1.25×10~(-3)Ω·cm)和高可见光透过率薄膜(90%)。研究结果表明该薄膜光学禁带约为3.85 eV,电阻率主要受载流子浓度控制,受溅射气压的变化影响有限。     

基于有限元/离散元耦合的大理石高速划擦过程仿真

针对大理石的磨粒加工过程,借助有限元/离散元耦合方法建立了单颗磨粒的高速划擦仿真模型,并通过在实体单元中插入零厚度内聚力单元,控制内聚力单元的失效来实现大理石加工过程中裂纹的萌生及扩展过程。基于所建立的单颗磨粒划擦模型,对比了划擦深度和划擦速度对大理石去除过程的影响。结果表明:大理石划擦过程中划擦力和加工表面损伤层厚度随划擦速度和划擦深度的增加而显著增大,且划擦力与损伤层厚度存在正相关性。      

金属薄膜结合性能的评价方法研究

针对Al2O3基体上磁控溅射沉积的Au／NiCr／Ta多层金属薄膜，用压痕法、滚动接触疲劳法、摩擦力和声发射两种模式同时监测的划痕法，对比研究了金属薄膜与基体的结合性能。结果表明：压痕试验从压痕形貌上很难判断薄膜与基体是否发生剥离，压入过程中也没有诱发裂纹的产生，更无法分辨薄膜层间的分离；由于金属薄膜的塑性变形，滚动接触疲劳法很难应用于金属薄膜结合性能的表征：划痕法可应用于多层金属薄膜的特异划擦行为研究，其中摩擦力模式能反映压头进入不同金属膜层时的变化，层间声发射信号的灵敏度不如摩擦力信号，对应试验条件，摩擦力曲线存在若干以拐点为特征的载荷，摩擦力曲线上出现的拐点及拐点特征载荷值可以在一定程度上反映多层膜的层数和层厚，并可刻划出该膜／基体系承受压入载荷而不发生剥落的能力。     

单颗磨粒划擦SiCf/SiC陶瓷基复合材料的试验研究

为研究SiC纤维(SiC_f)增强SiC陶瓷基复合材料(SiC_f/SiC)的磨削损伤机理,搭建试验平台开展单颗磨粒划擦试验,测量划擦力并观察其表面损伤形式,研究磨粒形状、划痕深度和SiC_f取向对复合材料磨削机理的影响。试验结果表明:SiC_f/SiC陶瓷基复合材料的划擦损伤形式主要有基体崩碎、纤维裂纹、断裂和拔出等。在SiC_f/SiC陶瓷基复合材料划擦过程中,尖锐状磨粒的划擦力更小,且整条划痕的表面损伤范围较扁平状磨粒的小。用扁平状磨粒划擦但纤维取向γ= 0°时,划痕形貌中纤维断裂、纤维拔出等损伤形式出现较少。      

金属轧制复合过程微观变形行为的分子动力学建模及研究

基于分子动力学方法研究金属层合板轧制复合过程界面区材料的微观变形行为,从力学性能和位错运动的角度,对比研究双金属FeCrNi/Fe与单金属的压缩变形,揭示非共格界面对金属微观变形行为的影响。结果表明,双金属模型与2种单金属模型在应力-应变关系和变形行为规律方面都存在明显差异;由于复合界面的存在,变形过程中双金属模型纯Fe基体中的位错在界面附近积累,界面原子的局部剪切作用使FeCrNi基体中的位错形成变得容易,降低了FeCrNi基体的屈服强度;复合界面对于变形过程中位错传播的阻碍作用,使材料抵抗塑性变形的能力得到提高,变形过程中2种金属基体内位错密度的交替变化导致2种金属基体的变形量也对应呈现交替变化的特殊现象。     

基于单磨粒划擦仿真的钛合金抛光机理研究

自由磨粒抛光被认为是最常用和最重要的抛光方法之一，抛光垫、自由磨粒和工件之间的相互作用形成了接触区域的材料去除，材料去除机理的研究对于抛光过程控制和工艺参数优化具有重要意义。建立了单磨粒划擦热-力耦合有限元模型，研究了钛合金抛光过程中的材料去除机理，发现了单个磨粒高速划擦过程中的“水漂效应”现象，且随着划擦速度的增加，这种效应越加明显。当在相同的划擦速度下减小划擦力时，材料去除方式由连续去除变为不连续去除。因此，当单个磨粒高速划擦时，会产生类似于轴向超声抛光的轨迹。该研究为钛合金抛光高速划擦过程中的微观材料去除机理提供了理论参考。     

基于FIB/SEM双束系统的原位、实时观测三点弯曲薄膜测试方法

目的 需要直接测量薄膜的极限形变这一关键参数，来评价某种薄膜在一定服役载荷下的某种基体表面是否能胜任。方法 借助聚焦离子束显微镜/扫描电子显微镜(FIB/SEM)双束显微分析测试系统，提出了一种在微米尺度下、原位进行三点弯曲薄膜测试的方法，同时可以进行实时观测与分析记录。之后，使用磁控溅射技术制备了具有强择优晶体生长取向的CrN薄膜和Cr/CrN多层薄膜，并使用上述三点弯曲测试方法对这两种薄膜进行了弯曲测试。结果 CrN薄膜的极限形变量为(1.8±0.1)%，且其在原位三点弯曲试验中断裂前的变形类型为纯弹性形变，而不是塑性形变或者弹性/塑性混合形变。而Cr/CrN多层薄膜的极限形变达到了9.1%，是纯CrN薄膜的5倍，且对“预裂纹”等缺陷不敏感。结论 将此测试方法与在微米尺度使用FIB测量薄膜残余应力的方法相结合，将可以有效地评估多种薄膜的形变能力及形变特性。所获得的薄膜相关性能数据，对于针对不同基体、不同使用工况(如不同的表面受力状态、变形状态等)的薄膜体系或结构的选择与设计，具有很好的指导意义。     

低模量Ti6Al4V表面Ti(Al/Pt)N薄膜强化改性

为解决硬质薄膜因与软基体硬度和模量差较大导致的薄膜失效问题,提高硬质薄膜在Ti6Al4V(TC4)钛合金基体上的适应性,使用掺杂氮化钛（TiN）陶瓷薄膜对低模量Ti6Al4V合金表面强化。采用热丝增强等离子体磁控溅射技术在Ti6Al4V合金表面制备Ti(Al/Pt)N薄膜：包括本征TiN、Al&Pt掺杂TiAlN和TiAl(Pt)N薄膜。采用扫描电子显微镜、X-射线衍射仪、纳米压痕仪、洛氏硬度计和摩擦磨损测试仪分别表征三种薄膜组织形貌、能谱分析、相结构和内应力、纳米硬度和模量及耐磨性。结果表明：Al元素掺杂使TiN薄膜柱状晶细化,截面形貌柱状晶更致密;同时微量Pt掺杂后,截面断口呈韧性撕裂。本征TiN和TiAlN薄膜衍射峰图谱呈现TiN(111)取向,TiAl(Pt)N薄膜的衍射峰呈TiN(200)主峰位。Al元素掺杂使TiN薄膜晶格畸变增多,内应力从-13 MPa增大到-115 MPa,导致膜-基结合力恶化,洛氏压痕和摩擦磨损实验中均出现薄膜剥落。Pt掺杂后薄膜内应力降低到-66 MPa,在洛氏压痕试验中TiAl(Pt)N薄膜与基体结合良好,仅有少许环形裂纹。摩擦磨损试验中本...     

离子液体热解制备CNx薄膜及其摩擦学性能

为探索简易的碳基薄膜材料制备工艺,采用一种新型碳氮基骨架先驱体——离子液体热解在Q235钢和304不锈钢表面制备了CNx薄膜,利用扫描电子显微镜(SEM)和拉曼光谱仪等对CNx薄膜的表面形貌和结构进行了分析,并对其摩擦学性能进行了考察。结果表明:制备的CNx薄膜结构主要是环状sp2相团簇的无定型结构;CNx薄膜具有良好的抗磨减摩特性和较高的承载能力。与Q235钢基底相比,304不锈钢表面制备的CNx薄膜裂纹少,摩擦过程中不易剥落,表现出更好的抗磨减摩效果。     

Loss of constraint on fracture in thin film structures due to creep

Fracture in thin films is normally constrained by the substrates. If the substrate creeps, however, the constraint will be lost over time. This paper presents a two-dimensional model for channel cracks in an elastic film on a viscous layer, and implements an extended finite element method to evolve the displacement field and the stress intensity factor with relatively coarse meshes. Solutions are obtained for stress intensity factors of channel cracks with several in-plane geometries. The stress intensity factor increases with time, indicating the loss of constraint. Several scaling laws are obtained. Extensions of the present model are outlined for nonlinear creeping and viscoelastic layers, as well as a thick viscous substrate. Fracture in thin film structures subjected to ratcheting deformation under cyclic temperatures using the analogy between creeping and ratcheting is also discussed.     

Effect of structural relaxation on plastic flow in a Ni–Nb metallic glassy film

The effect of structural relaxation on the deformation behavior of Ni₆₀Nb₄₀ glassy films was systematically investigated. The film and Ti substrate were co-bent and morphology evolution of the film during bending was monitored. With a decrease in thickness there was a mode change from highly localized to non-localized deformation, with the critical thickness dependent on annealing temperature. During co-bending only a proportion of the stored elastic energy in the metallic glassy film can transfer to the shear band due to the presence of the Ti substrate, which increases with annealing temperature due to the decrease in interfacial adhesion between the film and the substrate. Thus the decrease in critical thickness and the “thickness window” for deformation mode change caused by annealing arises from the enhanced hardness/Young’s modulus and the reduced interfacial adhesion.     

Corrosion of Al-Sn-Bi alloys in alcohols at high temperatures. Part II: Effect of anodizing on corrosion

Nine kinds of Al alloys were anodized to form porous anodic oxide films, and then anodized specimens were immersed in 2-(2-(2-methoxyethoxy)ethoxy)ethanol (MEEE) and 2-(2-(2-butoxyethoxy)ethoxy)ethanol (BEEE) at 415 K. Al-1.0%Sn-1.0%Bi alloy was corroded severely in both BEEE and MEEE, whereas other eight alloys showed no corrosion. The corrosion proceeded under the anodic oxide films through cracks formed in the film. Cathodic polarization in Cu electroplating solution after corrosion suggested that the crack formation during immersion in hot MEEE is due to thermal expansion of the substrate and Sn and Bi containing particles included in the anodic oxide film.     

Mechanical properties and microstructures of Al-Cu Thin films with various heat treatments

The relationship between microstructure and mechanical properties has been investigated in Al-Cu thin films. The Cu content in Al-Cu samples used in this study ranges from 0 to 2 wt.% and substrate curvature measurement was used to measure film stress. In thin films, the constraints on the film by the substrate influence the microstructure and mechanical properties. Al-Cu thin films cooled from high temperatures have a large density of dislocations due to the plastic deformation caused by the thermal mismatch between the film and substrate. The high density of dislocations in the thin film enables precipitates to form inside the grain even during a very rapid quenching. The presence of a large density of dislocations and precipitates will in turn cause precipitation hardening of the Al-Cu films. The precipitation hardening is dominant at lower temperatures, and solid solution hardening is observed at higher temperatures in the tensile regime. Pure Al films showed the same values of tensile and compressive yield stresses at a given temperature during stress-temperature cycling.     

热处理温度对镀镍钴钢带拉伸变形行为的影响(英文)

研究热处理温度对镀镍钴钢带微观结构和拉伸性能的影响。通过原位扫描电子显微镜观察镀镍钴钢带在拉伸变形过程中表面形貌的变化。结果表明:热处理后,镀镍钴钢带在镀层与基底之间形成镍/钴/铁扩散层,随着热处理温度的升高,钢带的伸长率逐渐增大;当热处理温度为 650 ℃时,镀镍钴钢带的伸长率最大,为 46%,抗拉强度和屈服强度适中。在拉伸变形过程中,镀镍钴钢带在热处理前、后呈现出不同的变形过程。未进行热处理的样品在拉伸变形过程中,表面形成裂纹,裂纹的扩展导致最终断裂;而热处理后,钢带在拉伸过程中表面没有裂纹的产生,孔洞的出现、生长和扩展而导致的最终断裂。这表明,适当的热处理有利于提高材料的韧性,改善其力学性能。     

Investigation on Mechanical Properties of Deformation TiNi Thin Films

The TiNi thin films were deposited onto copper substrates by magnetron sputtering. Tensile tests were carried out on CSS-44100 electron universal test-machine. X-ray diffraction profile Fourier analysis method and the Nano-Hardness Tester have been used to study the mechanical properties of deformation TiNi thin films. The mechanical properties of metals and alloys should be determined primarily by dislocation structure among these objects. The results showed that the dislocation density and the deformation storage energy density increased with the increasing elongation. Microhardness was calculated from the dislocation data. The results showed that the microhardness values were not having good agreement when comparing the calculated values with the measured values. The oxide layer on the surface and the precipitated phases of TiNi thin film affect the measured values of microhardness. The microhardness measured values were larger than the calculated values. The surface micrographs of the TiNi thin film were obtained using scanning electron microscopy (SEM). The experimental results showed that a series of parallel cracks grew in a concerted fashion across the thin film, and the cracks were equally spaced.