Fabrication of Y2O3 buffer layer on polished Ni substrates for YBCO superconducting tape

Highly cube textured Ni tapes are produced by heavy cold rolling and recrystallization annealing. The textured nickel tapes have been proven to be suitable substrates for YBCO superconducting tape. Nevertheless, rolling damage and grain boundary grooves on Ni influence the epitaxial growth of highly textured buffer and YBCO layers. The polishing of the Ni substrate surface may play a crucial role in making it beneficial to epitaxial film deposition. In our work, several polishing methods were adopted on Ni to reduce the depth of rolling damage and grain boundary grooves. On the polished Ni substrates, textured Y2O3 buffer layers were deposited using RF sputtering. XRD results show that in-plane texture of Y2O3 films will minish with the decreasing of the Ni substrate surface roughness. AFM results show that average grain size of the Y2O3 film is biggest and surface is coarse in film on flatter Ni surface.     

Fabrication of Y_2O_3 buffer layer on polished Ni substrates for YBCO superconducting tape

1IntroductionIn recent years,worldwide research efforts have been made to develop YBCOsuperconducting tapes.Two promising approaches for the profitable production of long YBCOtapes that are suitable for carryinghigh currents in magnetic fields are RABi TS(Rolling Assisted Biaxially Textured Substrates)[1]and IBAD(Ion Beam Assisted Deposition)methods[2].In RABi TS process,the necessarily strong biaxial texture ofthe YBCOfil mis achieved by epitaxial growth of buffer layers andthe …     

The surface morphologies of (Pb, Sr) TiO3 thin film fabricated on Si-buffered Pt/Ti/SiO2/Si substrate

(Pb, Sr)TiO3 (PST) thin film are fabricated by RF magnetron sputtering on Si-buffered Pt/Ti/SiO2/Si substrates with different buffer layer deposition time. Surface morphologies of the buffer layer indicate an improving surface roughness and larger grains with the prolongation of sputtering time. Deposition of PST thin films shows excellent surface fluctuation filling ability to improve the surface roughness of substrates. PST surface morphologies exhibit apparently different grain forms according to the preparation time durance of buffer layer.     

The surface morphologies of (Pb,Sr)TiO_3 thin film fabricated on Si-buffered Pt/Ti/SiO_2/Si substrate

1Introduction(Pb,Sr)Ti O3(PST)thin fil mhas great potentials in the application of microelectronic devices such astunable microwave filters,infrared detectors,DRAM,etc[1-3].Preparation of PST thin fil ms can be a-chieved by many methods including PLD and sol-gel[4].Perovskite thin fil msuch as(Ba,Sr)Ti O3(BST)prepared on Pt/Ti/Si O2/Si substrates has considerably higher dielectric loss compared with correspondingbulk materials,O2-vacancies generated ontheinterfaces between electrod…     

The surface morphologies of (Pb, Sr) TiO3 thin film fabricated on Si-buffered Pt/Ti/SiO2/Si substrate

(Pb, Sr)TiO3 (PST) thin film are fabricated by RF magnetron sputtering on Si-buffered Pt/Ti/SiO2/Si substrates with different buffer layer deposition time. Surface morphologies of the buffer layer indicate an improving surface roughness and larger grains with the prolongation of sputtering time. Deposition of PST thin films shows excellent surface fluctuation filling ability to improve the surface roughness of substrates. PST surface morphologies exhibit apparently different grain forms according to the preparation time durance of buffer layer.     

纳米Al2O3对Ni基合金激光抛光表面光洁度的影响

为提高激光抛光表面光洁度,采用1 070nm,200W光纤激光器(SPI激光器SP-200C-A-A6-A-C)进行激光抛光实验。首先在电镀纯Ni样品上进行实验,采用相同的参数对Ni/Al_2O_3(4.4%,体积百分比)纳米复合材料进行激光抛光。在其他参数相同的情况下,通过改变激光能量密度进行实验,最后通过形貌和微观结构表征研究Al_2O_3纳米颗粒对Ni抛光性能的影响,再利用光学和热物理性质对激光熔化进行了数值模拟。结果表明,在最佳激光抛光工艺条件下,Ni/Al_2O_3的表面粗糙度由323nm降低到72nm,纯Ni的表面粗糙度由254nm降低到107nm。在纳米颗粒的帮助下,标准化表面粗糙度降低了近2倍。激光加工区截面的微观结构研究表明,通过添加Al_2O_3纳米粒子,激光熔化区(MZ)深度从1.8μm增加到3.2μm,而热影响区(HAZ)的大小从8.4μm显著减小到2.9μm。激光抛光中通过纳米粒子调节熔池动力学,克服了激光抛光的基本限制。随着纳米粒子对热物理性质的改变,热毛细流动的开始发生了改变,从而为毛细区提供了更宽的处理窗口。纳米颗粒的增黏作用提高了毛细区的平滑效率。数值模拟进一步证明了纳米颗粒抑制了热传递,增强了表面层内的热积累,从而降低了MZ深度。纳米粒子限制了晶粒的生长,提高了晶粒生长温度,使热影响区缩小。     

Influence of the substrate thickness on texture of tape

Fabrication of a strong cube texture Ni substrate through thermomechanical process is reported by ORNL research group. Decreasing the substrate thickness, the engineering critical current density will be improved. Rolled substrates are electropolished to the final thichness of 100, 80, 50, 40, and 20 μm, respectively. Electropolished substrates are recrystallized at temperatures between 800-1000C and in a mixed atmosphere of 4, H2 in 99.99, purity Ar. Orientation mappings of recrystallizated tapes are conducted through an EBSD system mounted on a LEO-1450 SEM. The influence of the substrate thickness on texture of the tape is studied in this paper. Results show that with the decrease of substrate thickness, the texture of the tapes with the same recrystallization process is more and more closed to the exact position of cube orientation.     

Ni-Ti合金电化学抛光性能研究

为提高Ni-Ti合金的表面质量和抗蚀性,改善生物相容性,基于自行研制的电化学抛光系统及抛光液,以Ti50.8Ni(at.%)为基材在最佳工艺参数下进行纳米级电化学抛光实验。研究了电化学抛光对试件表面粗糙度和表面形貌的影响;与砂纸打磨、机械抛光、酸洗等表面处理方法做对比,研究了不同表面处理方法对试件亲疏水性能和腐蚀性能的影响。分别利用白光干涉仪、扫描电子显微镜、接触角测量仪、电化学工作站检测分析了材料表面粗糙度、表面形貌、亲疏水性能及腐蚀性能。结果表明,在最佳工艺参数下试件电化学抛光质量良好,表面粗糙度值显著降低至27.8 nm,表面平整均匀、光亮如镜;经电化学抛光的Ni-Ti合金表面呈疏水特性,改善了生物相容性,提高了耐腐蚀性。     

铜镍合金/NiFe2O4-10NiO复合陶瓷惰性阳极的制备及其性能研究*

以NiO、Fe2O3和铜、镍为主要原料,采用高能球磨—固相烧结法,制备出Cu-Ni-NiFe2O4-10NiO和(Cu-Ni合金)/NiFe2O4-10NiO金属陶瓷试样,研究了试样的物相组成、显微结构以及其体积密度、静态热腐蚀率、抗热震性和电导率。研究表明,合金粉的添加能够改善金属相的溢出现象并提高材料的物化性质。与Cu-Ni-NiFe2O4-10NiO金属陶瓷相比,合金粉均匀的弥散于陶瓷相中,减小了晶界间的势垒作用,使载流子更易通过晶界从而提高了试样的导电率,850℃时试样的电导率为60.7 S/cm;增大了材料的致密度;耐高温和抗冰晶石熔盐静态腐蚀率较低,平均腐蚀率降为12.62 mm/a;较大提高了试样的抗热震性。     

Al2O3粉体添加对烧结钕铁硼磁性能的影响

研究了在磁体制备过程中添加Al2O3粉体对(PrNd)31(AlCoCuGaZr)1.55B0.98Fe合金磁体密度、微观结构和磁性能的影响。结果表明,随着Al2O3粉末的增加,磁体密度和矫顽力都呈先上升后下降趋势,剩磁与最大磁能积缓慢下降。Al2O3粉末添加量为0.1%时,磁体密度提升0.01g/cm3,继续添加,密度开始下降;当添加量为0.2%磁体矫顽力显著提升（提高5%）,综合磁性能最佳。显微组织表明,适量添加Al2O3,磁体平均晶粒尺寸减小,能改善磁体显微组织,促进磁体致密化。此外分布在晶界中的Al2O3/Re2O3,能够钉扎晶界,细化晶粒,提高磁体矫顽力。     

碳热还原法制备氮化铝粉末

以无定形A12 O3 和石墨粉为原料 ,采用碳热还原法制备AlN粉末 ,重点探讨了原料摩尔比及粒度、催化剂的种类及含量、保温时间等因素对AlN粉末合成的影响 ,合成出粒径约为 1μm的纯AlN粉末。原料粒度越细越有利于AlN的生成 ,C/A12 O3 摩尔比以略大于 3为适宜 ,价廉的重质碳酸钙的催化效果优于Y2 O3     

晶界特征分布对1Cr18Ni9Ti奥氏体不锈钢绝热剪切带自组织的影响

通过形变热处理工艺优化不锈钢的晶界特征分布,并采用厚壁圆筒外爆压缩加载实验对形变热处理前后的试样进行动态加载,研究了晶界特征分布对1Cr18Ni9Ti奥氏体不锈钢绝热剪切带自组织的影响。结果表明,形变热处理工艺优化了不锈钢的晶界特征分布,特殊晶界比例尤其是∑3晶界比例分别从27.8%,18.9%提高到72.5%,55.8%,一般大角度晶界被小角度晶界和特殊晶粒团簇取代或阻断。加载后两种状态试样的剪切带的数量和间距差别较小,但是固溶试样剪切带的平均扩展速率为446 m/s,最长剪切带长度为2.33 mm,而形变热处理试样分别为338 m/s和1.75 mm。晶界特征分布优化对剪切带的形核影响较小,但是由于特殊晶界比例的提高,明显阻碍了绝热剪切带的扩展,提高了高速变形条件下的抗损伤能力。     

不同Ni含量的合金钢在高温水蒸气中的氧化行为研究

为了探究Ni含量与温度对合金钢氧化腐蚀行为的影响, 对3.5%Ni、5%Ni和9%Ni钢在540 ℃高温水蒸气中的氧化行为进行了研究, 并与9%Ni钢在600 ℃高温水蒸气中的氧化行为进行了对比。采用非连续称量法测定其动力学曲线, 通过扫描电子显微镜(SEM)观察氧化膜形貌, 用能谱仪(EDS)和X射线衍射(XRD)对元素成分和相组成进行了分析。结果表明, 在540 ℃氧化时, 3种合金钢的氧化动力学均符合抛物线规律;Ni含量增加, 氧化速率下降, 但有促进氧化膜脱落的倾向; 3种合金钢的氧化膜均由Fe₃O₄、Fe₂O₃和NiFe₂O₄组成, Ni元素增多可以促进产物中Fe₃O₄向Fe₂O₃转化。氧化膜分为两层, 层间存在孔洞; 内层富含NiFe₂O₄的尖晶石氧化物, 外层以Fe₃O₄和Fe₂O₃为主。温度升高时, 9%Ni钢的氧化速率提高, 氧化膜脱落时间提早; 表面氧化物形貌发生了改变, 从片状组织转化为颗粒状组织, 但温度升高并未改变9％Ni钢的氧化产物类别。     

Study on nickel nanoparticles surfacemodified SnO2 film

SnO2 film is widely used as a gas sensor, whereas, its gas sensitivity at low temperature is not satisfactory. Surface modification is an effective way to enhance sensitivity of SnO2 which is closely related to the surface morphology and microstructure of SnO2. In this paper, nickel nanoparticles surface-modified SnO2 films were prepared by D. C. magnetron sputtering. The effects of distribution and morphology of Ni particles on the surface of SnO2 on hydrogen sensitivity were studied. The results show that the sputtering time of Ni influences gas sensitivity of SnO2. With increasing the annealing temperature, Ni particles separate from SnO2 particles and gradually aggregate into spherical particles distributing uniformly on the surface of SnO2 film. The particle size, porosity, and specific surface area of Ni influence the gas sensitivity of SnO2 directly. Gas sensitivity examination indicates that the spherical Ni particles in a diameter of 100nm lead to the best modification. After heat treated at 800℃ for 3 hours, SnO2 film with 30s sputtering of Ni shows a gas sensitivity of 112, for 4000 ppm H2 at a operating temperature of 60℃.     

Cu-15Ni-8Sn-0.4Si合金铸态组织结构及成分偏析研究

用金相、扫描电镜及电子能谱微区成分分析等方法对添加少量Si的Cu-15Ni-8Sn合金的铸态组织结构及成分偏析进行了研究。结果发现：Cu-15Ni-8Sn-0.4Si合金的铸态组织分为三层，除具有明显的枝晶外，还有块状的（Cu、Ni)3Sn相和溶有少量Cu的Ni2Si和Ni3Sn相组成的第二层，在两层之间为组织形态复杂的过渡区。宏观上铸态组织存在Sn的反偏析，Sn的含量从外到内呈现下降趋势。与非真空熔铸相比真空熔铸能明显改善Cu-15Ni-8Sn-0.4Si合金反偏析现象。均匀化退火对改善Sn的反偏析作用不大；枝晶组织可基本消除，但Ni、Si元素形成的化合物仍难以完全溶解。添加少量Si的Cu-15Ni-8Sn合金由于Ni2Si和Ni3Si相的形成，通过阻碍晶粒长大和时效沉淀而强化合金。     

低应变SiGe/Si异质结构的应变弛豫与界面扩散

利用透射电子显微镜(TEM)和同步辐射X射线白光形貌术研究了低应变SiGe/Si异质结构应变弛豫和界面扩散。观察到SiGe外延层未发生应变弛豫,Si缓冲区和Si衬底中有颗粒状析出物。     

硫铁矿焙烧及反应过程的初步研究

在800℃下对含硫量50%的硫铁矿进行了沸腾焙烧,产出的硫铁矿烧渣硫含量低于0.30%,全铁含量大于64%。硫铁矿烧渣的主要矿物组成为赤铁矿、磁铁矿、磁赤铁矿。硫铁矿在焙烧过程中首先发生分解,在颗粒的表面上生成氧化产物或中间产物,体积膨胀,粒径增大,产生许多细微的裂纹,在氧气的亲和力和SO2向外逃逸产生的牵引力的作用下,使硫铁矿烧渣产生空洞。当反应温度升高,反应急剧进行,硫铁矿颗粒会发生爆炸反应,最终形成以Fe2O3为壳的小球形烧渣;或者形成以Fe3O4为基体,Fe2O3为包壳,Fe2O3柱状晶钉扎在Fe3O4基体上的实心硫铁矿烧渣。     

1235铝合金冷轧板表面黑丝缺陷分析

采用电解铝液直接铸轧生产厚度为7.0 mm,宽度为1 050 mm的1235铝合金铸轧板,经2道次冷轧成厚度为2.1 mm铝箔坯料。采用光学显微镜(OM)、扫描电子显微镜(SEM)及能谱仪(EDS)等对厚为2.1 mm冷轧板表面黑丝缺陷显微组织进行研究和分析,探讨黑丝缺陷形成的原因。结果表明,冷轧板表面黑丝缺陷局部存在不规则的凹坑,凹坑内存在粗大夹杂物及第二相颗粒,且退火冷轧板黑丝缺陷晶粒相对正常基体数量多且较小。能谱分析表明这些粗大夹杂物是富含Al和O元素组成的非金属氧化物Al_2O_3,第二相颗粒是由富含Fe、Al元素且含量较低的Si元素组成的金属间化合物Al Fe Si,因此造成冷轧板出现了黑丝缺陷。     

SCR7000连铸连轧铜杆扭转裂纹的关键影响因素

针对SCR7000工艺生产低氧光亮铜杆的扭转裂纹问题,采用SEM+EDS、OM等研究了铜杆中的杂质元素,中心与边部的晶粒尺寸及硬度差异,铜坯凝固组织异常等关键影响因素对扭转裂纹的影响。结果表明：铜杆扭转裂纹中存在Fe、Ni、Cr、Si等杂质元素的局部富集,产生了应力集中,诱导了铜杆表层的扭转裂纹。分析认为,这些杂质元素主要来自浇包、过滤器及钢溜嘴等材料的熔损;铜杆中心部位的平均晶粒尺寸、硬度与边部的差异大,导致扭转裂纹敏感性大,这是铜坯的入轧温度、轧制过程的铜杆冷却不合适、轧机与铜坯间的摩擦作用以及SCR7000工艺多道次轧制所致;铸轮结垢的严重程度与扭转裂纹的发生率存在明显的正相关关系,这是严重的铸轮结垢导致铜坯凝固组织异常所致。     

纳米WC制备过程中混料工艺及抑制剂作用的研究

利用成分分析和XRD, SEM 以及BET等检测手段, 对低温碳化工艺制备纳米级WC粉末进行了研究, 制备了平均晶粒度在20～30 nm, 颗粒尺寸小于100 nm的纳米碳化钨粉末。通过对滚筒混料和三维混料2种方式的对比研究发现, 三维混料比传统的滚筒混料具有更高的效率, 能使物料在较短的时间得到充分混合, 三维混料2 h即可达到滚筒混料6 h同样的效果, 并研究了不同混料时间和不同球料比对混料均匀度的影响。此外, 还研究对比了钨粉原料中添加晶粒抑制剂V₂O₅对碳化工艺的影响, 结果发现V₂O₅对碳化过程有延缓作用, 但对WC产物晶粒度及颗粒大小并无明显影响。