纳米多层复合镀层的制备及其应用研究

对近年来国内外纳米多层膜的研究文献进行了综述,介绍了纳米多层膜的电沉积制备、性能及应用,总结归纳了近年来人们对研究纳米多层膜所做出的工作,分析了纳米多层膜的发展趋势.     

纳米多层膜的研究现状

纳米多层膜是在单层膜与复合膜的基础上发展起来的一种新型薄膜,它被广泛应用于机械加工、航空航天、能源等领域,作为结构材料或功能材料都具有良好的发展前景。介绍了近十几年纳米多层膜的研究状况,主要从多层膜体系、制备技术、多层膜的性能以及多层膜的表征方法4个方面对纳米多层膜进行了综述,同时对纳米多层膜的超硬机制、纳米多层膜未来的研究方向和应用前景进行了分析。     

TiN/AlN纳米多层膜的制备及耐蚀性能

采用多弧离子镀技术制备了TiN/AlN纳米多层膜,并通过多层膜在酸中的浸泡试验及极化曲线测定,对比研究了TiN/AlN纳米多层膜和TiN薄膜的耐蚀性能.结果表明,由于TiN/AlN纳米多层膜中铝的钝化作用及薄膜的特殊层结构,TiN/AlN纳米多层膜比TiN薄膜具有更优良的耐腐蚀性能.     

纳米金属多层膜的电化学制备与性能研究的现状

介绍了金属多层膜电化学制备方法的现状,简述了单槽电化学制备多层膜材料的数学模型,比较了纳米金属多层膜与亚纳米金属多层膜不同的力学、电学、磁学、光学和电化学性能,并讨论了巨磁阻多层膜材料的应用前景。     

退火处理工艺在纳米多层膜材料研究中的应用进展

与传统块状材料相比,纳米多层膜因其小尺寸效应、表面效应、量子尺寸效应和宏观量子隧道效应,表现出独特的光、磁、电、力学和热学性能,可作为光电材料、光吸收材料、电磁波吸收材料、磁记录材料和低温连接材料,被广泛应用于光学器件、半导体、电磁防护、加工制造、表面防护以及电子封装等领域。纳米多层膜的微观结构与宏观物理力学性能具有强烈的尺度效应。由于受制备工艺所限,纳米多层膜内部存在的空位、位错等缺陷导致其在复杂服役环境中难以完全满足耐热、耐磨和耐腐蚀等要求,限制了纳米多层膜的发展。而在集成电路和芯片制造领域,纳米多层膜器件常处于偏离常温的苛刻工作环境中,具有较高表面自由能的亚稳态纳米多层膜在受热情况下会通过两相互扩散、层内脱离和界面结构变化等方式,趋向达到低能量的稳定结构,从而破坏了多层膜内部的微观结构,导致其熔点降低、超硬等特性消失或减弱。因此,研究纳米多层膜的微观结构演化、热稳定性及其失效机理,直接关系到纳米多层膜体系的服役寿命和可靠性。退火工艺作为一种常见的热处理手段,被广泛应用于消除金属内部的缺陷,从而达到改善材料性能的目的。对于在高温条件下工作的纳米多层膜,退火工艺也是延长其使用寿命的有效手段。目前退火工艺在纳米多层膜研究中的主要应用方向有:(1)通过改变退火温度、保温时间和冷却速度,改善纳米多层膜的性能;(2)通过提高退火上限温度,研究退火温度对纳米多层膜热稳定性的影响,获得保持微观结构稳定的临界温度。研究发现,适当的退火工艺可以细化纳米多层膜的晶粒结构,增加致密度,降低缺陷密度,诱导产生特殊结构,增强原子与位错的交互作用,从而提高薄膜的透光率,改善薄膜光学性能或磁学、电学和力学性能;(3)在一定温度区间内对纳米多层膜进行退火,通过TEM、XRD等手段观察多层膜内部界面的结构变化、原子扩散情况及新的物相生成情况,从而研究了纳米多层膜的结构稳定性、化学稳定性和力学稳定性。本文综述了退火工艺在纳米多层膜改性以及热稳定性研究中的应用进展,讨论了退火工艺对纳米多层膜性能(光学性能、磁学性能、电学性能、力学性能)的影响。重点介绍了退火处理温度对不互溶纳米多层膜体系热稳定性和组织演变的影响机理。最后指出了退火工艺在纳米多层膜研究中的进一步应用方向,以期对高强度、高热稳定性纳米多层膜的设计制备及在材料焊接/连接、集成电路、切削刀具、吸波涂层等领域的广泛应用提供重要的理论和应用价值。     

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。     

Ti-Si-N纳米多层膜的研究进展

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。     

不同调制周期的TiSiN/TaVN纳米多层膜的结构及性能

为了探究调制周期对TiSiN/TaVN纳米多层膜性能的影响,使用磁控溅射仪在304不锈钢和硅片上沉积TiSiN/TaVN纳米多层膜,采用X射线衍射仪、扫描电镜、纳米压痕仪、划痕仪、表面性能综合测试仪等分析和探索不同调制周期的TiSiN/TaVN纳米多层膜的微观结构、力学性能和摩擦学性能。结果表明：TiSiN/TaVN纳米多层膜均为面心立方结构,在(111)晶面和(200)晶面呈现择优取向。随着调制周期的增大,TiSiN/TaVN纳米多层膜的硬度、弹性模量、膜基结合力等先增大后减小,摩擦系数先减小后增大。当调制周期为8 nm时,TiSiN/TaVN纳米多层膜具有优异的力学性能和摩擦学性能,硬度最高为28.79 GPa,弹性模量最大为301 GPa,膜基结合力最高为29.2 N。薄膜硬度强化的主要原因是固溶强化和交变应力场。当调制周期为8 nm时,TiSiN/TaVN纳米多层膜的摩擦系数最小值为0.14,磨损机理主要为磨粒磨损和氧化磨损。TiSiN/TaVN纳米多层膜摩擦学性能改善的主要原因之一是摩擦过程中V元素与氧气反应形成了具有自润滑性能的Magnéli相氧化物V₂     

纳米金属多层膜的电制备与性能研究的现状

介绍了金属多层膜电化学制备方法的现状，简述了单槽电化学制备多层膜材料的数学模型，比较了纳米金属多层膜与亚纳米多心移层膜不同的力学、电学、磁学、光学和电化学性能，并了巨磁阻多层材料的应用前景。     

调制周期对TiB_2/TiAlN纳米多层膜机械性能的影响

利用射频磁控溅射技术,在室温下合成了具有纳米调制周期的TiB2/TiAlN多层膜.分别采用表面轮廓仪、纳米力学测试系统、多功能材料表面性能实验仪和XRD,分析了调制周期对TiB2/TiAlN纳米多层膜机械性能的影响.结果表明大部分多层膜的纳米硬度和弹性模量值都高于两种个体材料混合相的值,在调制周期为25 nm时,多层膜体系的硬度超过了36GPa,性能达到较佳效果.     

Microstructural evolution of Fe/Ti multilayers submitted to in situ thermal annealing

The Fe/Ti multilayers of nominal bilayer thickness of 4.0, 8.0 and 18.0 nm with alternating Fe and Ti sublayers thickness ratio of 1:1 were deposited by direct current magnetron sputtering on Si(100) substrates. The bilayer thickness of as-deposited Fe/Ti multilayers was measured as a modulation wavelength of 4.8, 8.5 and 19.0 nm, respectively, by small angle X-ray diffraction and cross-sectional transmission electron microscopy (XTEM). The three Fe/Ti multilayers were composed of pure metallic -Fe and -Ti according to wide angle X-ray diffraction and selected area diffraction. The Fe/Ti multilayers were in situ submitted to thermal vacuum annealing at the temperatures ranging from 523 K to 723 K for the annealing time of 3 h. With annealing at the lower temperature of 523 K, the intermetallic FeTi appeared in the Fe/Ti multilayers with small modulation wavelength of 4.8 nm. At 623 K, the intermetallic FeTi was formed with modulation wavelength of 8.5 nm. At the higher temperature of 723 K, the intermetallic FeTi was detected with modulation wavelength of 19.0 nm. The modulation wavelength of the Fe/Ti multilayers remained during the thermal annealing. The mixture of intermetallic FeTi and -Fe phase was observed in the extended Fe sublayer of the Fe/Ti multilayers annealed at 723 K by XTEM, correspondingly the remaining Ti sublayer was obtained as a thinned sublayer. Coexistence of the intermetallic FeTi, -Fe and -Ti phases indicated that the dynamic factors have control of the intermixing between the Fe and Ti sublayers in the Fe/Ti multilayers during the thermal annealing.     

退火对Al-Sb多层薄膜的影响

采用直流磁控溅射法制备Al和Sb交替层,在真空环境下进行高温退火后得到了AlSb多晶薄膜.通过X射线衍射(XRD)、霍尔效应、暗电导率温度关系以及透反射光谱研究了薄膜的结构、电学和光学性质.结果表明,退火后形成的AlSb多晶薄膜呈立方相,沿(111)择优取向,且导电类型是P型,载流子浓度为1019cm-3,吸收系数在可见光波段大于104cm-1.样品在580℃退火后,间接跃迁光能隙为1.64eV,且升温电导激活能为0.01eV和0.11eV.此方法制备的AlSb多晶薄膜应用于TCO/CdS/AlSb/ZnTe:Cu/Au结构的太阳能电池中,得到了107mV的开路电压.     

Theoretical explanation of Ag/Cu and Cu/Ni nanoscale multilayers softening

Relationship between metallic multilayers hardness and monolayer thickness has been investigated and explained for electroplated Ag/Cu and Cu/Ni multilayers using a modified Thomas-Fermi-Dirac electron theory. Experiments reveal that the peak hardness of Ag/Cu multilayers occurs at the monolayer thickness of about 25 nm, while the peak hardness of Cu/Ni multilayers occurs at about 50 nm. Critical monolayer thickness corresponding to the peak hardness is approximated by the grain size limit of stable dislocations in Ag crystals for the Ag/Cu multilayers and in Cu crystals for Cu/Ni multilayers. Grains size limits are calculated based on a modified Thomas-Fermi-Dirac electron theory. Developed relationship between the critical monolayer thickness and the grains size limit helps understand nanoscale metallic multilayers softening.     

Microstructure and In-plane Resistivity of Cu/Ni Multilayers

1.IDtroductiGnInrecellty6ars,interesthasgrowninmodulatedcompositestructurescomposedofperiodicallychang-inglayersoftwodifferentmaterials.Itwasshownthatthematerialsmayacquireimprovedqualitiestothoseofcorrespondingpuremetalswhenthemodu-lationwavelengthisverythinatafewnanometersinthickness.ItiswellknownthattheCu/Nimultilayershavebeenstudiedalotbecauseofitsabnormalphysicalproperties,includingelectricalresistivity[1,2],elasticmoduli[3],magneticproperties['l.Asthethicknessofanindividuallayerinmulti…     

Supermodulus effect by grain-boundary wetting in nanostructured multilayers

The effect of thermal treatments on mechanical properties was systematically investigated in Ni/Mo multilayers with a constant modulation period(160 nm)prepared by magnetron sputtering deposition.A supermodulus effect was found in the annealed multilayers as compared to the as-deposited state.A large tensile stress development was observed in the multilayers.The evolution of grain-boundary(GB)wetting was observed at the interfaces of the multilayers,which results in an enhanced modulus based on the mechanism of GB-wetting-induced interfacial stress/strain.The GB wetting phenomenon was further supported by a thermodynamic calculation.The results not only bring clear evidence of the important role of interfacial structures in governing the elastic behavior of metallic multilayers,but also allow designing the multilayers with special properties through atomic diffusion and wetting at the interfaces based on the thermodynamic calculation.     

X-ray diffraction and high resolution transmission electron microscopy characterization of intermetallics formed in Fe/Ti nanometer-scale multilayers during thermal annealing

Intermetallics formation in the Fe/Ti nanometer-scale multilayers magnetron-sputtering deposited on Si(100) substrate during thermal annealing at 623-873 K was investigated by using small and wide angle X-ray diffraction and cross-sectional high-resolution transmission electron microscopy. The Fe/Ti nanometer-scale multilayers were constructed with bilayer thickness of 16.2 nm and the sublayer thickness ratio of 1:1. At the annealing temperature of 623 K, intermetallics FeTi were formed by nucleation at the triple joins of α-Fe(Ti)/α-Ti interface and α-Ti grain boundary with an orientational correlation of FeTi(110)//α-Ti(100) and FeTi[001]//α-Ti[001] to adjacent α-Ti grains. The lateral growth of intermetallics FeTi which is dependent on the diffusion path of Ti led to a coalescence into an intermetallic layer. With an increase in the annealing temperature, intermetallics Fe₂Ti were formed between the intermetallics FeTi and the excess Fe due to the limitation of Fe and Ti atomic concentrations, resulting in the coexistence of intermetallics FeTi and Fe₂Ti. It was found that the low energy interface as well as the dominant diffusion path constrained the nucleation and growth of intermetallics during interfacial reaction in the nanometer-scale metallic multilayers.     

磁控溅射技术制备硅纳米晶多层膜及微观结构表征

在室温下,分别利用常规磁控溅射和反应磁控溅射技术交替沉积Si薄膜和Si1-xNx薄膜在单晶硅基体上制备了Si/Si1-xNx纳米多层膜。接下来,在高温下对Si/Si1-xNx多层膜进行退火诱发各层中形成硅纳米晶。研究了Si1-xNx层厚度和N2流量沉积对Si/Si1-xNx多层膜中Si量子点形成的影响。TEM检测结果表明,N2流量为2.5mL/min时沉积的多层膜退火后形成了尺寸为20～30nm的等轴Si3N4纳米晶;N2流量为5.0mL/min时沉积的多层膜退火后在Si层和Si1-xNx多层中均形成了硅纳米晶,而在7.5mL/min N2流量下沉积的Si/Si1-xNx多层膜退火后仅在Si层中形成了硅纳米晶。     

Structure, corrosion, and hardness properties of Ti/Al multilayers coated on NdFeB by magnetron sputtering

Ti/Al multilayers deposited on sintered NdFeB magnets by direct current magnetron sputtering with ion-beam assistance were studied in this report. Ti layers with a hexagonal close packed structure were obtained in the Ti/Al multilayers. The columnar structure growth of Al layers was successfully interrupted by the intercalated Ti layers. The Ti/Al multilayers showed more compact and uniform surfaces than the Al single layer. The corrosion current densities of the sintered NdFeB magnets coated with Ti/Al multilayers were much lower than that of the Al single layer. The Ti/Al multilayers also presented improved hardness.     

Oxidation behavior of TiN/ZrN multilayers annealed in air

Using reactive radio frequency magnetron sputtering, TiN/ZrN multilayers were deposited on Si (111) substrates at 550 °C. The multilayers were annealed at different temperatures ranging from 500 to 1100 °C in air. The variation of the annealed multilayers has been investigated by X-ray diffraction and transmission electron microscopy. A layer-by-layer oxidation behavior is found in the multilayers annealed at temperatures below 900 °C. The oxidation mechanism of multilayers is discussed in the paper.     

Sputter deposited nanocrystalline Ni-25Al alloy thin films and Ni/Ni3Al multilayers

Thin films of nominal composition Ni-25at%Al have been sputter deposited from a target of the intermetallic compound Ni₃Al at different substrate deposition temperatures. The film deposited on an unheated substrate exhibited a strongly textured columnar growth morphology and consisted of a mixture of metastable phases. Nanoindentation studies carried out on this film exhibited a strong strain hardening tendency. In contrast, the film deposited at 200 °C exhibited a recrystallized non-textured microstructure consisting of grains of a partially ordered Ni₃Al phase. At higher deposition temperatures (∼400 °C), larger grains of the bulk equilibrium, long-range ordered, Ll₂ Ni₃Al phase were observed in the film. Unlike the film deposited on an unheated substrate, the films deposited at elevated temperatures did not exhibit any dependence of the hardness on the indentation depth and, consequently no strain hardening. The average hardness of the film deposited at 200 °C was higher than the one deposited at 400 °C. In addition to monolithic Ni-25Al thin films, multilayered Ni/Ni3Al thin films were also deposited. Multilayers deposited non-epitaxially on unheated substrates exhibited a strong {111} fiber texture while those deposited epitaxially on (001) NaCl exhibited a {001} texture. Free-standing multilayers of both types of preferred orientations as well as of different layer thicknesses were deformed in tension untill fracture. Interestingly, the {111} oriented multilayers failed primarily by a brittle fracture while the {001} multilayers exhibited features of ductile fracture.