Effect of cooling rate on evolution of superconducting phases during decomposition and recrystallization of (Bi,Pb)-2223 core in Ag-sheathed tape

The reformation of (Bi,Pb)-2223 from the liquid or melt is very important for a melting process of (Bi,Pb)-2223 tape. By combination of quenching experiment with X-ray diffraction (XRD) analysis, the effect of cooling rate on the evolution of three superconducting phases in the (Bi,Pb)-2223 core of Ag-sheathed tape was investigated. The results show that (Bi,Pb)-2223 reformation from the melt seems to experience different routes during slowly cooling at different rates. One is that (Bi,Pb)-2223 phase reformed directly from the melt, and no Bi-2212 participate in this process. The other is that (Bi,Pb)-2223 is converted from the intermediate product, Bi-2212, which formed from the melt during the first cooling stage. Due to the inherent sluggish formation kinetics of (Bi,Pb)-2223 from Bi-2212, only partial (Bi,Pb)-2223 can finally be reformed with the second route.

Manufacturing of Ultra-high Molecular Weight Polyethylene Fiber Reinforced Tape and the Loss of Strength

Due to the low density and excellent mechanical proper-ties,high performance fiber reinforced materials have aconsiderable application in the area of high technologyand dally usage.In this paper,the Ultra-high Molecu-lar Weight Polyethylene(UHMWPE)fiber reinforcedPE tape prepared with the method of powder impregnat-ion was studied.The effect of impregnate length and thetensile force of the yarn on the fiber content as well as on the strength and modulus of the tape were discussed.Calculation shows that the strength and the modulus ofthe ULMWPE fiber can keep about 85％ after it undergothe process.

直孔三明治结构GDC-LSF双相复合透氧膜制备和性能研究

致密陶瓷透氧膜因在氧气制备和涉氧化工过程中的潜在重要应用而备受关注。本研究采用相转化流延/叠层/烧结工艺制备了三明治结构Gd_(0.1)Ce_(0.9)O_(2–δ)-La_(0.6)Sr_(0.4)FeO_(3–δ)(GDC-LSF)双相复合陶瓷透氧膜,其中部为起氧分离作用、厚度80μm的致密功能层,两侧为厚度420μm的直孔结构支撑层。采用浸渍法在支撑层内壁修饰Nd_(2)NiO_(4)+δ(NNO)纳米颗粒。在膜的一侧通入空气,另一侧通入氦气作为载气,测得900℃时氧渗透通量高达1.53 mL·cm^(−2)·min^(−1)。将氦气切换为CO_(2),测得氧渗透通量为0.6 mL·cm^(−2)·min^(−1),氧渗透在长达90 h的时间内保持稳定。该透氧膜经历70余次热循环(800~900℃)后仍保持完好。本研究表明:直孔三明治结构GDC-LSF透氧膜具有良好的氧渗透性能、化学稳定性和热机械性能,有望用于氧气分离和富氧燃烧/CO2捕获。

弹性织带生产中的问题分析与工艺调校

弹性机织带作为一种特种纺织品,在原料、织造技术、储运、染色上都有着特殊的要求。文章对弹性织带生产过程中常见问题,如宽度不一、弯带、起毛、跳线、起波的原因进行了详细阐述,就这些问题对产品质量的影响和工艺上的调校方法进行了分析总结。

热处理冷却过程对55钢尺带组织和性能的影响

研究了冷却板长度和冷却水温对55钢尺带力学性能的影响。结果表明:随着冷却板长度从200 mm增加到400 mm,尺带硬度从497 HV增加到583 HV,然后保持在此水平上,直线度从3.6 mm增加到最大值6.4 mm,呈单调增加变化;随着冷却水温从10°C升高到30°C,挺直度从1305 mm降到最小值825 mm,呈单调下降变化,疲劳寿命先增加后减少,呈抛物线状变化;当冷却板长度为300 mm、冷却水温为20 C时,尺带的硬度为581 HV,直线度为4.2 mm,疲劳寿命为6541次,挺直度为1238 mm,此时,显微组织为回火马氏体组织,无网状铁素体,为最佳的热处理工艺。

自动纸箱胶带封口装置

为了解决家具行业中块状长木板包装后封口问题,设计了一种纸箱胶带自动封口装置用于胶带自动封箱机。当裹包成盒后的纸板进入封口环节时,胶带夹转换位置自动拖动胶带,封口装置下行将胶带粘贴在箱板上。采用移动凸轮的直线推杆原理作为胶带封口装置的主要设计,并进行了样机研制和封口试验。试验效果表明封口后胶带贴合平整、无皱褶,纸箱封口稳固、牢靠。

内插自旋直齿扭带换热管压降及流场数值模拟

为了直观地描述内插自旋直齿扭带管内压降及流场的特性,建立了以水为介质的内插自旋直齿扭带换热管内流场的计算模型,采用RNGk~ε湍流模型对管内压降及流场的特性进行数值模拟研究。计算结果表明,扭带管的压降Δp与流体的流速u成抛物线关系,压降随着流速的增大而增大,并且大于空管的压降;扭带管的流体呈有规律的三维螺旋状流动,且存在二次流,扭带的直齿结构增强了流体的湍流程度;在近管壁区域,扭带管的流体轴向速度比空管平均提高幅度在33.05%~35.17%。

热处理工艺对55钢尺带力学性能的影响

研究了淬火温度和运行速度对55钢尺带力学性能的影响。结果表明:在840~920℃,随着淬火温度的增加,硬度和挺直度均逐渐增大。当尺带运行速度在150~190 mm/s时,随着运行速度的增加,抗拉强度和疲劳寿命均呈先增加后降低的变化趋势。当尺带运行速度为180 mm/s、在炉内900℃温度下淬火时,硬度为579 HV0.2,挺直度为1290 mm,抗拉强度为2423 N/mm2,抽拉试验疲劳寿命为6758次。此淬火温度和运行速度为最佳热处理工艺,此时,显微组织是马氏体。