Room-temperature synthesis and luminescence properties of Eu3+/Tb3+-doped La(1,3,5-BTC)(H2O)6

The facile, rapid, and effective synthesis of coordination polymer La(1,3,5-BTC)(H₂O)₆ has been realized via direct precipitation at room temperature. It is found that the crystal structure is of monoclinic, space group Cc. The doped Eu³⁺ or Tb³⁺ ions samples have the same phase and exhibit red and green emissions under UV light excitation, respectively.     

储油罐设计储存液位高度的计算

出于生产安全及经济安全的目的,根据标准规范的要求,需为储油罐设置液位保护或报警,满足储罐收发油作业安全平稳进行,实现这一目标的关键在于准确设定储罐的高、低液位报警高度。为设计储罐的储存液位,系统整理了固定顶罐和浮顶罐高、低液位的计算方法,利用积分和迭代算法详细论证了卧式罐单位时间内最大进/出液折算高度,进而计算卧式罐设计储存液位高度值,并以某油库现场卧式罐为例将计算值与现场设定参数进行比较。结果表明,计算所得卧式罐高、低液位报警高度与现场实际运行情况相符。     

Crystal structure and luminescence properties of a single‐component white‐light‐emitting phosphor Ca8ZnLa(PO4)7:Eu2+,Mn2+

A series of novel green emission Whitlockite‐type Ca₈ZnLa(PO₄)₇:Eu²⁺ and color tunable Ca₈ZnLa(PO₄)₇:Eu²⁺,Mn²⁺ phosphors were prepared by the solid‐state reaction method in a reducing atmosphere. Its crystal structure and phase composition were identified by high‐resolution transmission electron microscopy, selected area electronic diffraction, X‐ray photoelectron spectroscopy, and X‐ray powder diffraction Rietveld refinement, and it was found to be trigonal, belonging to R‐3c(161) space group. The luminescence properties of Eu²⁺ singly doped and Eu²⁺/Mn²⁺ codoped Ca₈ZnLa(PO₄)₇ phosphors were revealed in detail. Ca₈ZnLa(PO₄)₇:Eu²⁺ is excitable over a broad range from 200 to 450 nm with a prominent green emitting. With varied Eu²⁺/Mn²⁺ ratios, fine‐tune emission under 365 nm excitation can be achieved from green (0.221, 0.468) to magenta (0.391, 0.276), especially the warm white light (0.392, 0.352), and CCT 3500 K can be obtained by the process of energy transfer between Eu²⁺ and Mn²⁺. The ET mechanism in this system is managed via the dipole‐dipole interaction with the maximum energy‐transfer efficiency 82.8% based on the decay lifetime data. These results suggest that as‐prepared phosphors can serve as promising candidates of UV‐pumped w‐LEDs.     

旋轮参数对铝合金分形旋压的影响规律

铝合金分形旋压是一个复杂的多因素耦合影响的塑性成形过程,研究其旋轮参数对成形过程的影响可为相关成形参数的确定和优化设计提供理论依据。基于建立的可靠的铝合金分形旋压三维有限元模型,文章研究揭示了旋轮分形角、旋轮圆角半径、旋轮轴向进给比等旋轮参数对成形过程中的切向拉应力、周向压应力以及成形凸缘的不均匀变形程度和最终壁厚偏差的影响规律。结果表明,增大旋轮分形角,可以消除旋轮前方的金属堆积和降低成形过程中坯料开裂失效的可能性,可以使得成形凸缘的不均匀变形程度减小和成形精度降低;旋轮圆角半径的改变,对消除旋轮前方的金属堆积和降低成形过程中坯料开裂失效的可能性影响并不明显,但增大旋轮圆角半径,可以使得成形凸缘的不均匀变形程度增大和成形精度升高;旋轮轴向进给比的改变,对消除旋轮前方的金属堆积和成形凸缘的成形精度的影响并不明显,但增大旋轮轴向进给比,可以降低成形过程中坯料开裂失效的可能性,可以使得成形凸缘的不均匀变形程度减小。     

强流脉冲离子束辐照对DZ4合金微观结构的影响

利用成分为Cn+(30 mol%)和H+(70 mol%),加速电压为250 kV,脉冲宽度为70 ns,束流密度为100 A/cm2的强流脉冲离子束(high intensity pulsed ion beam-HIPIB)辐照DZ4镍基高温合金,辐照次数分别为5、10和15次.利用透射电子显微镜(TEM)分析辐照前后合金表层微观结构的变化.结果显示,与原始样品比较,辐照不同次数后的样品最表面都产生了一层晶粒度为5～10 nm的多晶层,它是由DZ4合金中各元素的单质相组成的.在距表面一定深度范围内,不存在γ'相;随着深度的增加,γ'相的含量逐渐增加.     

Template-free hydrothermal synthesis of single-crystalline SnO<Subscript>2</Subscript> nanocauliflowers and their optical properties

Large-scale single-crystalline SnO₂ nanocauliflowers were successfully synthesized using a hydrothermal growth method without any template. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). FE-SEM images show that the as-grown SnO₂ nanocauliflowers are constructed of tetragonal prisms with a width of 500–600 nm. XRD, EDS, and SAED results indicate that the as-grown SnO₂ nanocauliflowers are single crystalline with the tetragonal rutile crystalline structure. The growth mechanism of SnO₂ nanocauliflowers is also preliminarily discussed on the basis of different Sn(OH)₆²⁻ concentrations, and it is found that Sn(OH)₆²⁻ concentration plays an important role in determining the shape of the prepared SnO₂. Room temperature photoluminescence was further carried out on SnO₂ nanocauliflowers to investigate their optical properties. An intense blue luminescence centered at a wavelength of 424 nm is observed in the as-grown SnO₂ nanocauliflowers.     

电沉积制备纳米晶铁-镍-铬合金箔工艺及机理研究

以复合羧酸为配位剂,在含三价铬离子的水溶液中,电沉积制备Fe-Ni-Cr合金箔,研究铬盐浓度、电流密度和供电方式等对箔成分和成箔性能的影响,采用SEM、TEM、XRD和EDS对合金箔进行表征,对合金箔的力学、电和耐蚀性能进行研究,并研究合金箔沉积机理。结果表明,采用复合羧酸体系脉冲电沉积可制备出Cr的质量分数为5%~8%的高Cr光滑合金箔,其微观形貌为紧密堆砌的球状颗粒,晶粒尺寸10nm以内,主相为Cr与α-Fe或γ-Fe形成的固溶体。合金箔中Cr含量提高,箔的电阻率、硬度和耐蚀性也随之升高。Fe-Ni-Cr合金共沉积为电化学控制,由于Cr3+加入,合金沉积阻力加大,速度降低。     

铝合金发动机缸盖铸造工艺的计算机模拟分析

在对铝合金发动机缸盖进行工艺分析的基础上,制定了3组浇注方案,分别为缝隙式顶冒口补缩浇注系统、顶冒口直接浇注系统、半开放式半包围型横浇道浇注系统.通过使用铸造数值模拟软件对金属液的充型和凝固过程进行数值模拟,认为缝隙式顶冒口补缩浇注系统为最优方案.确定了缸盖的优化工艺参数:模具预热温度为400℃,浇注温度为720℃.在该组优化的工艺参数下,通过对金属液的充型和凝固过程的动态观察,预测了充型时间、凝固时间和可能存在的缩松、缩孔及气孔缺陷的分布与体积分数.     

添加剂对新型AgTiB2触头材料微结构和性能的影响

采用高能球磨和粉末冶金法制备了含不同添加剂的AgTiB2触头材料,系统研究了WO3、Al、Bi2O3以及WO3+Bi2O3、WO3+Al复合添加对AgTiB2材料微结构和性能的影响。采用扫描电子显微镜(SEM)和能谱仪(EDS)分析了AgTiB2复合粉末形貌和AgTiB2复合材料的组织,并对硬度和导电率进行测试。结果表明:WO3、Al+WO3与Bi2O3+WO3添加有助于提高AgTiB2复合材料致密度;与未添加的相比,单独添加WO3和复合添加Al+WO3的AgTiB2材料的硬度和导电率都有不同程度的增加,硬度分别为1253和1022 MPa,导电率分别为78.62%IACS和14.91%IACS;与未添加的相比,复合添加Bi2O3+WO3的AgTiB2材料硬度和导电率分别为786 MPa和16.12%IACS。     

Preparation and UV property nickel nanoparticles （〈10 nm） of size-controlled monodisperse by reductive method

Nickel nanoparticles (<10 nm) were successfully synthesized using a reductive method of nickel chloride with sodium borohydride in the ethanol/poly- vinylpyrrolidone (PVP) system. The effects of three factors, such as the concentration of the nickel ions, the time of reaction, and the amount of PVP (surfactant), were discussed. The possible growth process of the particles and optimum reactive conditions was also investigated. The result of transmission electron microscopy (TEM) reveals that these nickel nanoparticles are spherical. The average diameter could be controlled as 2-5 nm under selected conditions. High-resolution TEM and energy-dispersive spectroscopy results indicates that the nickel nanoparticles are pure. The UV-visible light absorption spectrum shows that the peaks of nickel nanoparticles moves toward the short wavelength along with the decrease of sizes.