Fabrication of Grain-oriented (Bi,Pb)_2Sr_2Ca_2Cu_3O_x Superconducting Tapes Using Magnetic Field and Vibration Technique

Highly textured (Bi,Pb)2Sr2Ca2Cu3Ox superconducting tapes have been fabricated by means of magnetic-field and vibration technique. This method is an effective way of improving the degree of grain alignment and density of oxide core in tapes after heat treatment and pressing cycles.Jc of above 20% was increased than that without treatment.

Positron Annihilation Study on TiC Powders

By means of the positron annihilation technique (PAT), superfine TiC powders obtained by ball-milling process were characterized. The results showed that there was a clear correlation between the change in TiC powders and that in the PAT parameters. In the high energy ball-milling process, TiC powders were severely deformed, which caused large increase in the amount of defects and severe distortion of lattice. On the other hand, the extreme refinement of grain size of powders resulted in the increase of grain boundary area and enhancement of system free energy. The spacing between deformed domains in 96 h milled samples is somewhat smaller than those in 48 h milled samples, indicating the size of Type II defects in 96 h milled samples is somewhat smaller than that in 48 h milled samples.

Microstructures and Mechanical Properties of TiC Particle Reinforced TiAl Composites by Spark Plasma Sintering

Using spark plasma sintering（SPS） technique, TiC particle reinforced γ-TiAl composites were prepared with varying weight fraction of TiC powders. The effects of the TiC fractions and distributions on the properties of the composites were investigated. The composite containing 7wt% TiC had the optimum three-point bending strength of 842 MPa,which was 200 MPa greater than that of the unreinforced γ-TiAl intermetallic. The degradation of the bending strength occurred in the composites containing more than 7wt% TiC and this was believed to be attributed to agglomerated particles of TiC, which acted as crack initiation and propagation sites. The increase of strength in TiC reinforced IMCs came from the grain refinement and the interaction of dislocations with the reinforcing particles. The bending strength of the IMC containing 7wt% TiC was theoretically estimated to increase by 85 MPa and 200 MPa, respectively, by the grain refinement and dislocation strengthening, the total of which was ahnost in accordance with the improvement in that of the unreinforced γ-TiAl intermetallic when considering normal estimation errors.

Fabrication of 2×2 Thermo-Optic Switches with Organic-Inorganic Hybrid Materials Prepared by Sol-Gel Technique

2×2 Mach-Zehnder interferometric thermo-optic switch was fabricated with organic/inorganic hybrid materials by sol-gel technique and direct UV patterning. The switching time of device was measured to be 4.2 ms and switching power 9.3 mW.

An overview of thermoelectric films:Fabrication techniques,classification,and regulation methods

Thermoelectric materials have aroused widespread concern due to their unique ability to directly convert heat to electricity without any moving parts or noxious emissions.Taking advantages of two-dimensional structures of thermoelectric films,the potential applications of thermoelectric materials are diversified,particularly in microdevices.Well-controlled nanostructures in thermoelectric films are effective to optimize the electrical and thermal transport,which can significantly improve the performance of thermoelectric materials.In this paper,various physical and chemical approaches to fabricate thermoelectric films,including inorganic,organic,and inorganic–organic composites,are summarized,where more attentions are paid on the inorganic thermoelectric films for their excellent thermoelectric responses.Additionally,strategies for enhancing the performance of thermoelectric films are also discussed.

Fabrication and Mechanical Properties of TiC/TiAl Composites

TiC/TiAl composites with different TiC content were fabricated by rapid heating technique of spark plasma sintering (SPS). The effect of TiC particles on microstructure and mechanical properties of TiAl Matrix was investigated. The results indicate that grain sizes of TiAl matrix decrease and mechanical properties are improved because of the addition of TiC particles. The composites display a 26.8% increase in bending strength when 10 wt% TiC is added and 43.8% improvement in fracture toughness when 5 wt% TiC is added compared to values of TiC-free materials. Grain-refinement and dispersion-strengthening were the main strengthening mechanism. The improvement of fracture toughness was due to the deflexion of TiC particles to the crack.

Three-dimensional isotropic microfabrication in glass using spatiotemporal focusing of high-repetition-rate femtosecond laser pulses

To improve the processing efficiency and extend the tuning range of 3D isotropic fabrication,we apply the simultaneous spatiotemporal focusing(SSTF)technique to a high-repetition-rate femtosecond(fs)fiber laser system.In the SSTF scheme,we propose a pulse compensation scheme for the fiber laser with a narrow spectral bandwidth by building an extra-cavity pulse stretcher.We further demonstrate truly 3D isotropic microfabrication in photosensitive glass with a tunable resolution ranging from 8μm to 22μm using the SSTF of fs laser pulses.Moreover,we systematically investigate the influences of pulse energy,writing speed,processing depth,and spherical aberration on the fabrication resolution.As a proof-of-concept demonstration,the SSTF scheme was further employed for the fs laser-assisted etching of complicated glass microfluidic structures with 3D uniform sizes.The developed technique can be extended to many applications such as advanced photonics,3D biomimetic printing,micro-electromechanical systems,and lab-on-a-chips.

Low-damage photolithography for magnetically doped(Bi,Sb)_(2)Te_(3) quantum anomalous Hall thin films

We have developed a low-damage photolithography method for magnetically doped(Bi,Sb)_(2)Te_(3)quantum anomalous Hall(QAH) thin films incorporating an additional resist layer of poly(methyl methacrylate)(PMMA). By performing control experiments on the transport properties of five devices at varied gate voltages(V_(g)s), we revealed that the modified photolithography method enables fabricating QAH devices with the transport and magnetic properties unaffected by fabrication process. Our experiment represents a step towards the production of novel micro-structured electronic devices based on the dissipationless QAH chiral edge states.

Photoelectrochemical CO_(2) electrolyzers: From photoelectrode fabrication to reactor configuration

The photoelectrochemical conversion of CO_(2) into value-added products emerges as an attractive approach to alleviate climate change. One of the main challenges in deploying this technology is, however, the development and optimization of(photo)electrodes and photoelectrolyzers. This review focuses on the fabrication processes, structure, and characterization of(photo)electrodes, covering a wide range of fabrication techniques, from rudimentary to automated fabrication processes. The work also highlights the most relevant features of(photo)electrodes, with special emphasis on how to measure and optimize them. Finally, the review analyses the integration of(photo)electrodes in different photoelectrolyzer architectures, analyzing the most recent research work that comprises photocathode, photoanode,photocathode-photoanode, and tandem photoelectrolyzer configurations to ideally achieve self-sustained CO_(2) conversion systems. Overall, comprehensive guidelines are provided for future advancements in developing effective devices for CO_(2) conversion, bridging the gap towards the use of sunlight as the unique energy input and practical applications.

聚合物光纤发光面料的设计与开发

为了满足人们对纺织品个性化和多样化的需求,以聚合物光纤(POF)为发光体,依据光纤侧面发光原理设计开发聚合物光纤发光机织面料,介绍面料的灵感来源、光纤分布设计、组织设计、纱线设计及其排列、穿综设计、上机织造工艺等,在半自动打样机上进行试织并说明织造要点。结果表明:合理利用发光体和其他纱线,结合纬向管状组织、平纹小提花组织以及缂丝技术等,开发出更加时尚化、个性化的发光面料。发光面料主要应用于装饰纺织品,其结构独特、配色协调、立体感强,具有较强的装饰性和乐趣性,在一定程度上也起到安全警示作用。

TiC制备技术及其增强SiC基复合材料的研究进展

TiC具有较高的断裂韧性、高熔点、高硬度等一系列的优异性能,是一种很有前途的工程材料。本文概述了TiC粉末的各种制备技术的研究现状,总结了近些年来国内外在TiC增强SiC基复合材料制备技术方面的最新研究进展,同时对未来的发展方向进行了展望。

铸造法制备TiC/ZA43复合材料的试验研究

以Ｔｉ，Ａｌ，Ｃ粉末为原料，采用ＸＤ法与铸造法相结合的工艺制备了体积分数为５％的ＴｉＣ／ＺＡ４３复合材料，研究了ＴｉＣ／ＺＡ４３复合材料的铸态组织以及增强相ＴｉＣ颗粒的尺寸与分布。试验结果表明：ＴｉＣ在复合材料中具有良好的稳定性，且随着Ａｌ－ＴｉＣ预制块加入温度的提高，颗粒分布更加均匀，晶粒细化效果更为显著。

TiC颗粒增强钛基复合材料的制备及其微观组织

采用直接加入TiC粉的方法制备了原位自生TiC增强钛基复合材料 ,此法与国内研究者常用的加入石墨粉的方法相比 ,制备的复合材料成分准确 ,易于控制。制备的复合材料由Ti和TiC相组成 ,其中TiC为初生树枝状和短棒状共晶组成。TEM研究发现 :还存在 0 .3～ 0 .6 μm的规则块状TiC ,多分布在晶界上 ;TiC颗粒与基体界面干净、无反应层 ,基体中存在较多的位错 。

The internal COF features in Dome A of Antarctica revealed by multi-polarization-plane RES

The ice exceeding one million years old has significant meaning for verifying and interpreting the middle Pleistocene transition （MPT） and the relationship between greenhouse gas and climate change. The region near Dome A in Antarctica satisfies the conditions for obtaining million-years-old ice since it has low temperatures and low accumulation rates. We analyze the corresponding relation between radar wave features and the crystal orientation fabric （COF） types based on the results of multi-polarization plane radio echo sounding （RES）. The results show that, even in the summit of the ice sheet, the COF type is not perfect, but is an elongated single-pole COF. Principal-axis-orientation differences of the COF among the different periods exist and reveal that the ice flow orientations are not constant but deviate clockwise with the increasing depth. This may be related to the adjacent basal valley or both height and position changes of the summit during the glacial-interglacial periods.

TiC+TiB_2协同增强Al-Cu原位复合材料

为利用TiC和TiB2的协同增强作用,采用基于熔体接触反应法和混合盐反应法的新工艺"两步法"制备了(TiC+TiB2)/Al-2Cu原位复合材料.利用扫描电子显微镜及差式扫描量热计对热处理前后的原位复合材料进行了组织及热分析,结果表明:组织中两相粒子的分布比单相粒子增强的情况更加均匀,而且T4处理实现了两相粒子真正意义上的均匀相间分布;相对于单一的Al-2Cu合金,(TiC+TiB2)/Al-2Cu的熔化开始温度和凝固开始温度升高,熔化潜热和凝固潜热增大,体系稳定性从而得以提高,T4处理进一步增大了这一趋势.

激光熔覆原位合成TiC/Ti复合材料试验研究

利用激光熔覆技术,在工业纯钛表面原位合成了 TiC/Ti复合材料。结果表明:选择不同的激光熔覆工艺参数,可使碳粉和Ti粉通过原位合成反应在钛表面生成TiC/Ti复合材料熔覆层;激光功率和扫描速率是影响熔覆层质量的主要因素:激光功率越大,形成的增强相颗粒尺寸越大,相应合金元素氧化也越严重;扫描速率越大,Ti与 C的作用时间变短,增强相颗粒尺寸越细小,且增强相所占的体积分数也相应减少。用 XRD、DES和 SEM证明了 TiC颗粒的存在,同时发现颗粒分布具有一定的均匀性,原位生成的TiC颗粒主要以等轴状和块状两种形态存在。

钛合金表面激光熔覆TiC/Ti-Ti_2 Co涂层耐磨性

为了提高钛合金的耐磨性能,以Co基合金粉末、钛粉和活性碳为原料,利用激光熔覆技术在TC4钛合金基材表面制得以原位自生TiC为增强相的耐磨涂层,用光学显微镜、扫描电子显微镜、X射线衍射仪和能谱仪等分析了涂层的显微组织、相组成及成分,在室温干滑动磨损条件下测试了涂层的室温耐磨性能。结果表明,原位生成的TiC增强相主要以发达树枝晶形态均匀分布于β-Ti,Ti_2Co共晶组织基体中;β-Ti为不规则枝晶或胞状晶,而Ti_2Co主要呈不规则块状分布,少量-Ti_2Co以片层状形成于β-Ti枝晶臂间;涂层与基材呈良好的冶金结合,显微硬度约HV600～HV700,具有优异的室温干滑动磨损性能,其中,硬质TiC相起主要抗磨作用。这一结果对提高钛合金的耐磨性能是有帮助的。

TiC/Cu复合材料的研究进展

本文介绍了陶瓷基TiC/Cu复合材料的研究进展,主要叙述了TiC/Cu复合材料的几种制备方法,并概括了TiC/Cu复合材料的基本性能。

激光熔覆原位合成TiC-TiB_2增强钴基复合涂层的研究

为了提高零件表面强度和耐磨性,以TiO2,Al,B4C和KF-Co50合金粉末为原料,利用激光熔覆技术,采用预置粉末法,在Q235钢基体表面原位合成了TiC-TiB2增强Co基复合涂层。使用金相显微镜、扫描电镜和X射线衍射仪对熔覆层的组织和物相进行了分析,并对熔覆层的显微硬度及耐磨性能进行了测试。结果表明,熔覆层与基材呈现良好的冶金结合,组织致密,无裂纹、气孔等缺陷;熔覆层的主要组成相有γ-Co,TiC,TiB2,Cr23C6等;熔覆层平均显微硬度达770HV0.2,耐磨性能优异。这一结果对提高零件使用寿命具有积极意义。

激光熔覆H13-TiC梯度复合涂层的制备与组织性能

为了解决高温下热应力导致的常规涂层脱落与开裂,在H13钢表面激光熔覆制备了H13-TiC梯度复合涂层,采用扫描电镜、X射线衍射、电子探针能谱等技术对梯度涂层的组织形貌、成分分布、硬度和热稳定性进行了分析。结果表明,涂层主要由Fe-Cr,TiC,TiO_2和Fe_7C_3等物相组成,其中TiC呈现近多面体、枝晶态等外形;随着TiC含量的增加,TiC颗粒的尺寸变大,梯度涂层的硬度逐渐提高,结合区的枝晶组织逐渐变小,呈现明显的梯度分布;600℃高温加热空冷处理后,各层间重熔软化区硬度下降幅度最大,其次为基体H13钢,整体上硬度仍呈梯度分布。可以看出,激光熔覆H13-TiC梯度复合涂层有着极大的应用潜力。