Zr基氮化物／金属Cu纳米多层膜的强韧化研究

多层结构可以提高材料的强度、弹性模量和韧性。当尺寸减小到纳米量级时,性能将产生飞跃变化。首先探讨了多层结构提高强度、弹性模量和韧性等性能的基本原理,然后阐明了纳米尺度效应及理论,重点以过渡族金属氮化物ZrN纳米多层膜为例,研究了氮化物／金属（ZrN／Cu）纳米多层膜、ZrAIN纳米复合膜以及ZrAIN／Cu纳米多层膜的强韧化性能。结果表明,ZrN／Cu纳米多层膜的断裂韧性约是二元ZrN薄膜的2倍。当纳米多层膜的Cu单层厚度为2013131时,多层膜的K1C值最高。ZrAIN复合膜的断裂韧性与Al含量密切相关,当Al原子分数为23％时,薄膜的KIc值达3．17MPa·m^1/2,其硬度〉40Gpa,Al原子分数为47％的薄膜的K1C值则降低到1．13MPa·m…。,其硬度降低至17．1GPa。与z州／cu纳米多层膜和ZrAlN复合膜相比,以ZrAIN层和cu层为调制结构制备的ZrAlN／Cu纳米多层膜具有最高的硬度和最好的韧性。     

Al/Al2O3多层膜的表面和界面的分析研究

用热蒸发沉积和自然氧化及加热法制备纳米量级的Al/Al2O3薄膜和多层膜.用X射线光电子谱仪(XPS)和透射电镜(TEM)对样品进行检测.XPS实验说明自然氧化的Al2O3膜层厚在2～5 nm.Al/Al2O3薄膜及多层膜的O与Al的原子浓度比为1.43～1.85.Ar离子刻蚀的XPS实验结果(刻蚀速率为0.09 nm/s)说明2个对层的Al/Al2O3多层膜截面样品具有周期性结构.TEM观察到了5个对层的Al/Al2O3多层膜的层状态结构,其周期为4 nm.由此说明,热蒸发及自然氧化法是制备纳米量级的Al/Al2O3多层膜的有效方法.     

WC/DLC纳米多层膜微观结构研究

阳极层流型气体离子源与非平衡磁控溅射复合技术沉积制备WC/DLC纳米多层膜,并在膜/基间设计了中间过渡层.用扫描电镜、拉曼光谱仪、光电子能谱仪、X衍射仪、透射电镜、干涉显微镜等,对WC/DLC纳米多层膜的微观形貌结构进行分析研究.结果表明:沉积的WC/DLC膜层表面致密、光滑细腻;多层调制周期在3～4 nn,多层界面不清晰,形成渐变过渡界面.WC/DLC膜中主要是sp2键中掺杂有一定量的sp3键,WC则以纳米晶结构弥散分布在DLC之中.     

陶瓷硬质纳米多层膜研究进展

陶瓷纳米多层膜因具超硬效应而成为近年的研究热点.本文对这类人工材料的研究进展和存在的不足进行了评述,并展望了进一步研究的方向.二十年来,陶瓷纳米多层膜的实验研究已取得明显进展:在微结构特征方面,两调制层形成共格外延生长结构是纳米多层膜产生超硬效应的必要微结构条件已成为共识;材料组合方面,由于模板效应,不同结构类型的材料,甚至非晶材料都可在纳米多层膜中形成共格外延生长结构,高硬度纳米多层膜材料体系已得到大大的拓展.与此相比较,对纳米多层膜强化机制和设计准则的研究相对滞后,仍停留在以金属纳米多层膜基于位错运动受阻于界面的理论解释上.因而,建立适合于陶瓷纳米多层膜的强化机制和设计准则;拓展纳米多层膜的材料组合,开发以碳化物、硼化物甚至氧化物为基的纳米多层膜将成为进一步研究的方向.     

金属纳米多层膜力学性能研究进展

新型功能材料及器件向小型化,集成化和复合化发展的趋势,使得尺寸在纳米尺度的层状材料和柔性多层器件在使用过程中的服役行为成为其发展的关键科学问题。本文结合作者近几年对Ag/M系列和Cu/M系列多层膜力学性能的研究工作,对金属纳米多层膜的微结构特征及其对力学性能的影响进行了回顾和总结,主要包括多层膜的晶粒形貌对其强化机制和塑性变形行为的影响,组元强度错配对多层膜硬化行为的影响,界面结构与其强度极值的关系、不对称界面结构引起的异常弹性模量增强和多层膜的室温蠕变机制及界面结构对蠕变性能的影响等几个方面,并对多层膜的力学性能研究进行了展望。     

Al/Ta纳米多层膜中的结构形貌稳定性演化

采用磁控溅射技术制备了调制波长从18-108 nm的Al/Ta金属多层膜,并研究多层膜沉积过程中的截面结构形貌演化,实验表明,薄膜结构形貌演化分为四个阶段：孕育,萌生,发展和湮灭,可能是因为弹性失配引起的,并且随调制波长的增加呈现逐渐减弱的趋势。单向拉伸实验表明,这些结构形貌的非稳定区域严重影响力学行为,非稳区域往往是潜在的裂纹萌生区域。     

射频磁控溅射沉积Al/Al2O3纳米多层膜的结构及性能

运用射频磁控溅射技术在Si(100)基片及40Cr钢基体上制备了调制周期λ=60 nm,调制比η=0.25～3的Al/Al2O3纳米多层膜.通过X射线衍射、X射线光电子能谱、扫描电镜、原子力显微镜、维氏显微硬度仪及MFT-4000多功能材料表面性能测试仪对多层膜的结构、硬度、膜基结合强度及摩擦性能进行了研究.结果表明:Al/Al2O3多层膜中Al层呈现(111)择优取向,Al2O3层以非晶形式存在,多层膜呈现良好的调制结构.薄膜与衬底之间的结合强度较高,均在40N左右,摩擦系数均低于衬底的摩擦系数,表明Al/Al2O3多层膜具有一定的减摩作用.η=0.25的Al/Al2O3多层膜具有最高的硬度值(16.1GPa),摩擦系数最低(0.21),耐磨性能最好.     

金属/高熵合金纳米多层膜的制备、微观结构及力学性能研究进展

通过表面防护涂层技术制备综合力学性能与摩擦性能优异的涂层材料,对降低构件因碰撞摩擦磨损所引起的损伤失效问题十分重要。相较于单层膜结构防护涂层,金属纳米多层膜涂层材料由于其微观组织结构的独特性与可控性,表现出优异的服役特性,且其综合性能可通过结合新组元或界面调控得到进一步提高,因此该类材料受到了广泛关注。新颖的成分设计理念使得高熵合金具有独特的四大效应,即高熵效应、晶格畸变效应、迟滞扩散效应和性能鸡尾酒效应,进而呈现出良好的综合性能。因此,在传统的双金属纳米多层膜结构材料中引入高熵合金组元,形成金属/高熵合金纳米多层膜,有望突破传统金属纳米多层膜的性能局限,极大地提高多层膜结构材料的力学性能。从功能基元序构的视角,围绕近几年金属/高熵合金纳米多层膜的相关研究,首先介绍了其制备方法和工艺原理,针对功能基元微观结构特征,从晶粒形貌、界面结构、组元成分等方面进行了阐释,在此基础上论述了其力学行为以及相应的内在机制,并提出了调控金属/高熵合金纳米多层膜力学性能的优化策略,最后对金属/高熵合金纳米多层膜的未来研究方向和面临的挑战进行展望。     

Al/Al2O3多层膜的表面和界面的分析研究

用热蒸发沉积和自然氧化及加热法制备纳米量级的Al/Al2 O3薄膜和多层膜。用X射线光电子谱仪 (XPS)和透射电镜 (TEM)对样品进行检测。XPS实验说明自然氧化的Al2 O3膜层厚在 2～ 5nm。Al/Al2 O3薄膜及多层膜的O与Al的原子浓度比为 1 4 3～ 1 85。Ar离子刻蚀的XPS实验结果 (刻蚀速率为 0 0 9nm/s)说明 :2个对层的Al/Al2 O3多层膜截面样品具有周期性结构。TEM观察到了 5个对层的Al/Al2 O3多层膜的层状态结构 ,其周期为 4nm。由此说明 ,热蒸发及自然氧化法是制备纳米量级的Al/Al2 O3多层膜的有效方法     

6061铝合金钛锆铈化学转化成膜过程及膜层的耐蚀性能

为进一步改善6061铝合金表面无铬化学转化膜的综合性能,以H2TiF6和H2ZrF6为主成膜剂,铈盐、偏磷酸盐等辅助成膜剂,制备了具有较高耐蚀性能的Ti-Zr-Ce化学转化膜。通过扫描电镜及能谱仪分析转化膜表面形貌及元素构成,并采用电子探针显微分析仪观察不同成膜阶段的铝合金微区结构的变化规律,研究了6061铝合金表面Ti-Zr-Ce化学转化成膜过程及膜层耐蚀性能。结果表明:膜层主要含有Al、O、Ti、P元素,还含有少量F、Zr元素,推测主要成分为TiO2,ZrO2,Al2O3及少量磷化物;极化曲线和交流阻抗测试表明Ti-Zr-Ce化学转化膜具有较好的耐蚀性能,反应时间为150s时制备的Ti-Zr-Ce转化膜试样的腐蚀电位为-0.577V,腐蚀电流密度较低,为0.115μA/cm^2.     

Pb^2＋与Al^3＋掺杂对SiO2薄膜电荷贮存性能的影响

较高的表面能是ＳｉＯ２薄膜产生亲水性并导致体内贮存电荷失稳的重要原因。极性Ｐｂ６２＋离子的掺入有效地降低了ＳｉＯ２薄膜的表面能，使表面趋于中性，增强了疏水性。此外，Ｐｂ＾２＋，Ａｌ＾３＋离子作为填隙式离子和替位式离的掺入较好地改善了ＳｉＯ２薄膜的网络结构并使其致密化，使样品在保持原有良好的负电荷存储性能基础上，又对称增增加了优良的正电荷贮存能力。     

Early Stage Morphology of Quench Condensed Ag, Pb and Pb/Ag Hybrid Films

In situ Scanning Tunneling Microscopy (STM) has been used to study the morphology of Ag, Pb and Pb/Ag bilayer films fabricated by quench condensation of the elements onto cold (T = 77 K) inert and atomically flat Highly Oriented Pyrolytic Graphite (HOPG) substrates. All films are thinner than 10 nm and show a granular structure that is consistent with earlier studies of Quench condensed (QC) films. The average lateral diameter, & of the Ag grains, however, depends on whether the Ag is deposited directly on HOPG (&=13 nm) or on a Pb film consisting of a single layer of Pb grains (&=26.8 nm). In addition, the critical thickness for electrical conduction (d_G) of Pb/Ag films on inert glass substrates is substantially larger than for pure Ag films. These results are evidence that the structure of the underlying substrate exerts an influence on the size of the grains in QC films. We propose a qualitative explanation for this phenomenon.     

热循环对快速凝固Al90Pb10合金结构形态的影响

利用差示扫描量热计(DSC)和透射电子显微镜(TEM),研究了用快速凝固法制备的Al90Pb10合金样品经三次DSC热循环处理前后的结构形态变化.结果表明,Al90 Pb10合金经热循环处理后,纳米镶嵌Pb颗粒发生了奥斯特瓦德(Ostwald)熟化,Al90Pb10合金中的位错形态也因此发生改变.也讨论了这种结构形态变化的内在机制.     

铅对(Pbx,Sr1-x)0.85Bi0.1TiO3薄膜结构与介电可调性影响的研究

用溶胶-凝胶法制备了（Pbx，Sr1-x）0．85Bi0．1TiO3薄膜，对其晶相结构、微观形貌和介电可调性进行了研究．结果表明，该薄膜以钙钛矿形式存在．快速热处理过程可分解得到高活性离子，直接形成比相应温度平衡状态析晶时更多的晶相量．这种晶相在一定条件下有分解和再结晶的趋势．随着Pb^2＋离子增加和Sr^2＋离子减少，钙钛矿相的四方相与立方相间的转变温度升高．薄膜处在铁电相和顺电相转变点附近时，可以获得较大的可调性．     

铅过量PLZT铁电薄膜的制备及其电学性质研究

采用Sol Gel法 ,在Pt TiO2 Si基片上制备了具有不同铅过量 (0— 2 0mol% )的PLZT铁电薄膜。分析了薄膜的晶相结构 ,研究了铅过量对PLZT铁电薄膜的介电性能和铁电性能的影响。结果表明 ,各薄膜均具有钙钛矿型结构 ,且各薄膜均呈 (110 )择优取向。PLZT铁电薄膜的介电性能和铁电性能随铅过量的变化而改变。铅过量为 10mol%的薄膜具有最佳的的介电性能和铁电性能。     

Mg4 Al3/CuO/Pb3 O4爆响剂的配方优化及声辐射特征?

为了寻求具有宽频特征的燃烧型烟火水声药剂材料,基于爆炸声具有水声频带较宽的特点,将Mg_4Al_3/CuO/Pb_3O_4爆响剂引入水下。首先,研究Mg_4Al_3/CuO/Pb_3O_4爆响剂中Pb_3O_4组分含量变化对A声压级的影响规律,并优选出A声压级最高的药剂,制成样品,并在水下点燃,利用水声测试系统研究其声频特征。结果表明,Mg_4Al_3/CuO/Pb_3O_4爆响剂A声压级随着Pb_3O_4含量的增加而增大,当外加Pb_3O_4的质量分数为75%~100%时,A声压级最高,可达到108.3 d B。将此Mg_4Al_3/CuO/Pb_3O_4爆响剂与烟火药制成样品,在水下点燃,产生的水声频率覆盖0~8 000 Hz,且出现锯齿形峰,0~1 000 Hz范围内最大声压级为116 d B。因此,Mg_4Al_3/CuO/Pb_3O_4爆响剂可作为一种潜在水声干扰材料。     

The formation of reacted film and its influence on tribological properties of extruded Al-Si-Cu-20-25Pb alloy under dry sliding

The friction and wear characteristics of AlSiCuPb alloys, especially antiseizure, have been investigated under dry sliding for a wide range of load. It is shown that hot extrusion considerably improved antiseizure properties of stircast AlSiCuPb alloys, and a stable wear rate with the lowest level of coefficient of friction are found to be controlled by the formation of a reacted film covering almost the entire worn surfaces of specimens under high applied load. The reacted film consists of compounds containing Al, Si, Pb and O. The reacted film is generally found to play significant role in improving the ability to resist seizure for AlSiCuPb alloys containing 20 wt% and 25 wt% lead.     

Quantum size effect in absorption of low energy electrons in Pb layers

Absorption of low-energy electrons in Pb ultrathin layers grown on a Si(1 1 1)-(6×6)Au substrate has been measured as a function of the incident electron energy and of the film thickness. The thickness-dependent curves of the current revealed two distinct features. One of them is associated with the quantum size effect and showed the characteristic oscillatory behavior with the periodicity determined by the film thickness. The other, independent of the film thickness, was attributed to the bulk band structure of Pb.On the basis of the changes in the quantum size oscillations peak position as a function of the transmitted electron energy, and of the layer thickness, the electronic band structure of Pb 8-20 eV above the vacuum level has been determined in the ΓL direction.     

Interfaces between Pb grains and Cu surfaces

The interfaces between liquid or solid Pb islands and single- or poly-crystalline Cu substrates are investigated. EBSD (Electron backscattered diffraction) analyses show that when Pb is solidified from droplets, a cube-on-cube orientation relationship prevails between the Pb crystals and each Cu grain surface, whatever its surface orientation, even though the lattice parameter of Pb is 1.37 times larger than that of Cu. Scanning electron microscope (SEM) and atomic force microscope (AFM) analyses show that during annealing of Pb droplets, ridges develop at the droplet-substrate triple lines, indicating that the interfaces evolve towards equilibrium by diffusional processes. These features are discussed in comparison with experiments and calculations performed on Pb nanocrystals embedded in Al, another fcc solid with a lattice parameter smaller than that of Pb. It is proposed that the cube-on-cube orientation relationship results from the solidification of Pb along the {111} planes of the solid Cu/liquid Pb interface which have developed by diffusion during the process of equilibration of the interface shape.     

Superconductivity of nanostructured Pb7Bi3 films doped by Ce

By means of electrochemical deposition from electrolytes, containing salts of Pb and Bi (0.03 mol/l and 0.02 mol/l respectively) thin films of intermetallic Pb7Bi3 have been fabricated. The superconducting transition temperature of the films was measured to be around 7.8 K. The deposition of the films with thickness of 50-100 nm was performed via passing rectangular current pulses with given amplitude and length. It was shown that adding salt of Ce into the electrolyte leads to a significant growth of the Tc for the deposited films reaching its maximum at the salt concentration of 0.06 mol/I. X-ray analysis data revealed the single phase of Pb7Bi3 films with hexagonal structure (SG) having a textures parallel to (101) plane. The morphology of the film surface is characterized by nanocluster structure with typical grain size around 70-80 nm. For the films, fabricated with adding salt of Ce, together with the intermetallic phase of Pb7Bi3, the second phase containing Bi is detected. At the same time, the typical grain size is reduced to 20-30 nm. Additionally, the suppression of the superconductivity in the grown films is investigated. The influence of the composition and structure on the superconducting critical temperature is discussed for both types of the fabricated films.