立方织构Ni-Cr-Mo-W合金薄带及其性能

为了得到高份额立方织构金属基带,同时兼顾居里温度和屈服强度的要求,设计了Ni-7.8%Cr-1.1%Mo-1.6%W(原子分数)合金。采用冷坩埚悬浮熔炼技术冶炼合金铸锭,铸锭经过锻造、热轧、冷轧和再结晶退火,最终得到厚度为100μm的合金薄带。采用电子背散射衍射(EBSD)技术对合金薄带再结晶织构进行了表征,并研究了其磁性能及力学性能。结果表明:经大变形量冷轧和优化的两步法退火后Ni-7.8%Cr-1.1%Mo-1.6%W合金薄带立方织构份额为93.4%,小角晶界体积分数为84.5%;合金薄带的居里温度为25K,远低于77K;合金薄带室温下的屈服强度为182 MPa,与Ni-5%W合金相当,且抗拉性能十分优异。     

加工率对Ni5W合金基带立方织构的影响

以镍粉和钨粉为起始原料,采用粉末冶金的方法形成Ni5W预合金锭,采用真空电弧炉去除杂质,实现均匀化。结合热轧、冷轧和再结晶热处理等工艺制备了厚度为80μm的Ni5W合金基带。讨论了道次加工率、总加工率对Ni5W合金基带轧制织构演变的影响。结果表明,较小的道次加工率和较大的总加工率有利于基带再结晶热处理后立方织构百分含量的提高,道次加工率对立方织构质量的影响小于总加工率。以5%的道次加工率和98%的总加工率进行冷轧后,获得了具有较高含量的S型织构和Copper型织构的基带。     

基于EBSD技术对NiW合金复合基带表面微取向的分析

采用EBSD技术对大冷轧变形量、再结晶退火后的Ni-W复合基带的表面织构进行了表征，对其晶粒取向信息、晶界特征等信息进行采集和分析。该基带经过冷轧和再结晶退火后，无需抛光，即可获得具有花样质量较高的Ni基复合基带表面的EBSD图像。经Orientation Imaging Microscopy^TM（OIM）4．6软件分析，结果表明该Ni基复合基带表面10°以内立方织构晶粒百分含量为97．9％。     

再结晶退火过程中Ni5W合金基带的结构转变

研究了YBCO涂层导体用的立方织构Ni5W合金基带在1 000℃下快速加热和快速冷却处理时的结构变化.X射线检测结果表明,热处理时间小于20min时,和立方织构百分数大小有关的I200/I111强度比随热处理时间的增加而快速增加.热处理时间从1 min增加至20 min,I200/I111强度比从10快速增加至103数量级.当热处理时间大于20min之后,I200/I111强度比随热处理时间的增加而明显降低.当热处理时间超过10 min之后,伴随I200/I111强度比的增加,Ni5W合金的晶格常数变小.实际上,Ni5W合金基带中的立方织构形成非常迅速,在1 000℃下,热处理10～20 min,样品中的立方织构百分数已接近100%.EBSD对样品进行立方织构百分数测量的结果和XRD分析结果非常一致,而且,EBSD的测量结果表明,对应立方织构百分数的增加,晶粒尺寸突然增加.本研究得到了较合适的加工和热处理制度,并用这样的制度制作出了具有锐利立方织构的Ni5W合金基带.     

全化学溶胶-凝胶方法在Ni金属基带上金属氧化物的制备及其在YBCO覆膜导体制备中的应用研究

今天,基于高性能YBCO覆膜导体技术的第二代高温超导导线正在得到越来越多的重视和研究.尤其是近几年来,采用全化学溶胶-凝胶方法在金属基带上制备YBCO覆膜导体的技术,由于具有成本低、可以精确控制金属组元的配比、可以在复杂形状表面均匀成膜等特点,引起了世界范围内广泛的兴趣和研究.本文主要报道采用全化学溶胶-凝胶工艺在RABiTS Ni双轴织构金属基带和我们新近发展的ISM工艺Ni双轴织构金属基带上织构金属氧化物(CeO2、BaxSr1-xTiO3)的制备及其表征.着重讲述RABiTS工艺和ISM工艺的不同原理以及在这两种金属基带上织构氧化物的形成过程和结构差别.最后,讲述我们在多层氧化物缓冲层制备方面的一些尝试以及在此缓冲层上YBCO超导层的制备及结果.     

化学溶液沉积法制备Y2O3过渡层

为了满足YBa2Cu3O7(YBCO)超导带材生产实际的需要,在金属基带和YBCO超导薄膜之间制备一层合适的氧化物过渡层显得尤为重要。以乙酸钇为原料配制前驱体溶液,采用金属盐化学溶液沉积法在织构的Ni-5%W(质量分数)(Ni-5W)带上成功制备了Y_2O_3过渡层。结果显示,氮气氛下1050℃热处理1h后,所获得的Y_2O_3过渡层具有良好的晶体织构,晶体生长取向为(100),完全复制了Ni-5W带模板的结构,为YBCO生长提供了良好的模板。在Y_2O_3过渡层上制备的YBCO薄膜表现出良好的超导性能。     

涂层导体用NiW合金基带表面改性研究

由于硫元素与氧元素化学特性的相近,在Ni基带表面形成硫的c（2×2）-S有序超结构有助于控制在金属Ni基带表面生长的氧化物膜的织构类型。目前,大多数关于在Ni基带表面形成c（2×2）-S超结构的研究报道,都集中于以硫化氢气体作为硫源,采用先吸附后脱附的方法形成该结构。首次提出通过硫化铵水溶液硫化NiW合金基带,再通过热处理去除无序的物理吸附层,形成有序c（2×2）-S超结构的新技术路线。采用AES和RHEED分别对采用新硫化技术处理后的样品表面成分和结构进行研究,并通过XRD对硫化前后的NiW基带上采用化学溶液技术制备的缓冲层织构进行了研究。结果显示,采用新技术处理的金属基带表面有明显的硫元素存在,并且硫在NiW合金基带表面形成了c（2×2）-S超结构。新硫化处理技术改善了NiW基带表面的物理化学特性,有利于氧化物缓冲层的外延生长。     

低成本电化学法制备RE2Zr2O7缓冲层

为了降低第二代高温超导涂层导体的制备成本,采用电化学法(ED),在双轴织构的Ni-5at%W(Ni-5W)金属基带上分别成功制备出了具有较好c轴取向的La2Zr2O7(LZO)和Gd2Zr2O7(GZO)缓冲层.通过与磁控溅射方法(MS)相结合,制备出MS-CeO2/ED-RE2Zr2O7双层结构,用以取代完全用磁控溅射方法(MS)制备的多层缓冲层结构.电化学法得到的60 nm LZO缓冲层的面内和面外织构半高宽分别为7.2°和6.8°,同样厚度的GZO缓冲层的面内和面外半高宽分别为6.7°和5.8°.之后用脉冲激光沉积(PLD)在ED-LZO/Ni-5W,ED-GZO/Ni-5W,MS-CeO2/ED-LZO/Ni-5W三种结构的缓冲层上分别制备出具有超导性能的YBa2Cu3O7-δ(YBCO)超导层.     

YBCO覆膜导体低成本制备研究

报道新近发展的离子束结构改性(ISM)技术以及同步织构(STEX)技术在YBCO覆膜导体制备中的最新进展。采用TFA-MOD工艺成功的在LaAlO_3(100)衬底上制备出了临界电流密度高达6.5 MA/cm~2 (77K,0T)的YBCO超导薄膜,其超导转变温度接近91K;同时还在LaAlO_3(100)衬底上成功地采用溶胶-凝胶工艺制备出了具有高度外延双轴织构取向的SrTiO_3缓冲层材料;在YSZ(100)衬底上采用溶胶-凝胶工艺制备出了具有高度双轴织构取向的CeO_2缓冲层材料。随后在这两种衬底上采用TFA-MOD工艺沉积的YBCO超导薄膜也获得了超过1MA/cm~2(77K,0T)的临界电流密度。作为制备实用化YBCO超导带材的新路线,在数厘米长的IBAD-YSZ/Hastelloy金属基带模板上,采用低成本化学溶液方法依次制备出了高质量的CeO_2缓冲层和YBCO超导薄膜,获得了高达1.2MA/cm~2(77K,0T)的临界电流密度。为长超导带材的制备打下了很好的基础。提出了在金属基带上制备YBCO覆膜导体的新方法一同步织构(STEX)法。用该方法可以有效解决RABiTS方法中的金属基带热处理变软...     

制备高温超导涂层导体的技术路线分析

钇系高温超导涂层导体具备优异的超导性能,有广泛的应用前景,因此成为国际上的研究热点之一。近年来涂层导体长带的研制在日本和美国等国家取得了巨大进展,目前主要的技术路线为离子束辅助沉积(IBAD)和轧制辅助双轴织构基带(RABiTS)2种,其中IBAD技术路线的使用更为广泛而且产品性能处于领先地位。基于对上述2种技术路线进行的对比分析研究,介绍了目前世界范围内主要研究单位的进展情况,并对这2种技术路线在涂层导体结构的3个基本部分(金属基带、过渡层、超导层)的制备情况进行了具体对比分析。     

Mechanical properties of pure Ni and Ni-alloy substrate materials for Y-Ba-Cu-O coated superconductors

Mechanical properties of rolling-assisted, biaxially-textured substrates (RABiTS) and substrates for ion-beam assisted deposition (IBAD) coated superconductors are measured at room temperature, 76, and 4 K. Yield strength, Young’s modulus, and the proportional limit of elasticity are determined, tabulated and compared. Results obtained are intended to serve as a database of mechanical properties of substrates having the same anneal state and texture as those incorporated in the general class of RE-Ba-Cu-O coated conductor composites (RE = rare earth). The RABiTS materials measured are pure Ni, Ni-13at.%Cr, Ni-3at.%W-2at.%Fe, Ni-10at.%Cr-2at.%W, and Ni-5at.%W. The IBAD substrate materials included Inconel 625 and Hastelloy C-276. The Ni alloys are substantially stronger and show higher strains at the proportional limit than those of pure Ni. Substrates fully coated with buffer layers, ≈1 μm of Y-Ba-Cu-O, and 3-5 μm of Ag have similar mechanical properties (at 76 K) as the substrate alone. Somewhat surprisingly, plating an additional 30-40 μm of Cu stabilizer onto high-yield-strength (690 MPa) Hastelloy coated conductors ∼100 μm thick, reduces the overall yield strength of the composite structure by only about 10-12% at 76 K and 12-14% at room temperature; this indicates that the Cu layer, despite its relatively soft nature, contributes significantly to the overall strength of even high-strength coated conductors.     

Investigation of cube-textured Ni-7at.%W alloy substrates for YBa2Cu3O7-δ coated superconductors

Ni-7at.%W alloys were fabricated by powder metallurgy process. After heavy cold-rolling and recrystallization annealing, sharp cube-textured Ni-7at.%W substrates were obtained. Deformation and recrystallization textures of Ni-7at.%W alloys were studied systematically. It was found that intermediate annealing during the process of cold-rolling is beneficial to the formation of a cube texture in the Ni-7at.%W substrate.     

Investigation of cube-textured Ni-7at.%W alloy substrates for YBaCuO coated superconductors

Ni-7at.%W alloys were fabricated by powder metallurgy process. After heavy cold-rolling and recrystallization annealing, sharp cube-textured Ni-7at.%W substrates were obtained. Deformation and recrystallization textures of Ni-7at.%W alloys were studied systematically. It was found that intermediate annealing during the process of cold-rolling is beneficial to the formation of a cube texture in the Ni-7at.%W substrate.     

Growth of thick chemical solution derived pyrochlore La2Zr2O7 buffer layers for YBa2Cu3O7−x coated conductors

The preparation of several 100 nm thick La₂Zr₂O₇ (LZO) buffer layers on biaxially textured Ni-5 at.%W substrates using chemical solution deposition is studied. This oxide material is currently of great interest for the fabrication of YBa₂Cu₃O_7−x (YBCO) coated conductors. Buffer layers for these coated conductors are required to have thicknesses greater than 100 nm in order to guarantee a sufficient barrier function against metal diffusion from the substrate. In this work, single LZO buffer layers with thicknesses exceeding 200 nm have been prepared. Detailed investigations were carried out in order to study the texture development with increasing thickness as well as the microstructure of these layers. Independent of the thickness, high quality buffer layers showing a distinct biaxial texture up to the surface, smooth surfaces, and a sufficient barrier function against Ni diffusion from the substrate have been reproducibly obtained. The high performance of these chemical solution derived LZO buffer layers was confirmed by a YBCO critical current density J_c of 1.0 MA/cm² (77 K, 0 T) achieved for a coated conductor sample with a layer sequence YBCO/CeO₂/LZO(CSD)/Ni-5 at.%W where CeO₂ and YBCO were deposited by pulsed laser deposition.     

Textured tapes of three-layer Ni-5% W/Ni-11% Cr composite: Substrates for second-generation superconductors

We have studied the formation of recrystallization texture in three-layer Ni-5% W/Ni-11% Cr composite tapes obtained through cold rolling to 98.4–99.3% followed by high-temperature annealing at 1000–1150°C. It is established that the textured three-layer composite tapes can be used as substrates for creating second-generation high-temperature superconductor (HTS) ribbons. Estimation of the magnetic properties of as-annealed composite tapes showed that their magnetization at HTS working temperatures is lower than that of widely used commercial Ni-5% W alloy tapes.     

Preparation and Characterization of TiN Seed Layer in All-Conductive Multilayer Structure for Coated Conductors

TiN films were successfully prepared on biaxially textured Ni-5 at.%W substrates by pulsed laser deposition (PLD), serving as a seed layer of an all-conductive architecture, i.e., SrRuO₃(SRO)/TiN, for coated conductors. The structure and surface morphology of the TiN films were noticeably affected by the substrate temperature and pulse repetition rate. The subsequent conductive SRO and superconducting YBCO layer were deposited on the best sample of TiN buffered Ni-5 at.%W substrates. X-ray diffraction analysis confirmed that the biaxial textures were transferred from the TiN seed layer to the SRO cap layer and YBCO film with excellent out-of-plane and in-plane textures. The superconducting transition curves and the temperature-dependent resistivity of YBCO films on all-conductive buffer and on the traditional insulated CeO₂/YSZ/Y₂O₃ were also investigated.     

超薄Ni81Fe19薄膜的各向异性磁电阻及磁性能

利用磁控溅射方法制备了一系列超薄Ta(5nm)/Ni81Fe19(20nm)/Ta(3nm)磁性薄膜。着重研究了基片温度、缓冲层厚度对Ni81Fe19薄膜各相异性磁电阻(AMR)及磁性能的影响。利用X射线衍射仪分析了薄膜结构、晶粒取向;用四探针技术测量了薄膜的电阻率和各向异性磁电阻;用FD-SMOKE-A表面磁光克尔效应试验系统测量了薄膜的磁滞回线。结果表明:在基片温度为400℃时制备的Ni81Fe19薄膜具有较大的各向异性磁电阻效应和较低的磁化饱和场,薄膜最大各向异性磁电阻为3.5%,最低磁化饱和场为739.67A/m。基片温度为500℃制备的薄膜,饱和磁化强度Ms值最大。随着缓冲层厚度x的增加,坡莫合金薄膜的AMR值先变大后减小,在x=5nm时达到最大值。     

聚苯醚/钙镧钛微波复合基板

微波复合基板兼具树脂基体的高韧性和陶瓷填料优异的介电和热学性能, 是航空航天、电子对抗、5G通讯等领域的关键材料。本工作采用螺杆造粒与注塑成型相结合的新技术制备了聚苯醚(简写为PPO)为基体、钙镧钛(Ca_0.7La_0.2TiO₃, 简写为CLT)陶瓷为填料的新型微波复合基板, 并对基板的显微结构、微波介电性能、热学性能和力学性能进行表征。结果表明, 采用这种新技术制备的微波复合基板组成均匀且结构致密。随着CLT陶瓷的体积分数从0增大至50%, 基板的介电常数从2.65提高到12.81, 介电损耗从3.5×10 ^-3降低至2.0×10 ^-3 (@10GHz); 同时热膨胀系数从7.64×10 ^-5 ℃ ^-1显著降低至1.49×10 ^-5 ℃ ^-1, 热导率从0.19 W·m ^-1·K ^-1提高至0.55 W·m ^-1·K ^-1; 此外抗弯强度从97.9 MPa提高至128.7 MPa。填充体积分数40%CLT陶瓷的复合基板综合性能优异: ε_r=10.27, tanδ=2.0×10 ^-3(@10GHz), α=2.91×10 ^-5 ℃ ^-1, λ=0.47 W·m ^-1·K ^-1, σ_s=128.7 MPa, 在航空航天、电子对抗、5G通讯等领域具有良好的应用前景。     

多孔Ni-WC复合电极的制备及其在酸性溶液中的电催化析氢性能

目前,关于多孔Ni-WC电极的电催化析氢(HER)性能的报道较少。以多孔海绵镍为基体,采用复合电沉积制备多孔Ni-(WC)x复合电极。运用扫描电镜(SEM)和X射仪线衍射仪(XRD)表征电极的表面形貌和微观结构,通过阴极极化、电化学阻抗(EIS)、循环伏安、计时电流法研究多孔Ni-(WC)x电极在0.5 mol/L H2SO4溶液中的电催化析氢性能。结果表明:与多孔基体Ni电极相比,多孔Ni-(WC)x电极具有较低的析氢过电位、较低的电化学反应阻抗、较小的表观活化能以及较大的交换电流密度;随着镀液中WC浓度的升高,所制备的多孔Ni-(WC)x电极的电催化析氢活性增强,其中Ni-(WC)40电极的表观交换电流密度是多孔Ni基体电极的966.7倍,其表观活化能为5.95 kJ/mol,并具有较好的耐蚀性和析氢稳定性。