氧化硅微孔材料对烟气中挥发性羰基化合物的吸附研究

为降低卷烟烟气中有害成分挥发性羰基化合物的含量和研究微孔材料在卷烟减害中的应用,将氧化硅微孔材料通过复合嘴棒方式应用到卷烟中,分析其对主流烟气中八种挥发性羰基化合物含量的影响。结果显示氧化硅微孔材料对挥发性羰基化合物有明显的吸附作用。其中,对巴豆醛、丙烯醛、甲醛、2-丁酮的脱除率均超过50%;对丙醛、丁醛、丙酮的脱除率超过30%。烟气三项指标分析表明,氧化硅微孔材料对烟气中的焦油和烟碱含量影响不大。通过与非极性吸附材料活性炭的比对,认为氧化硅微孔材料对挥发性羰基化合物的吸附主要与其高比表面、丰富的微孔结构有关,而与其极性相关性不强。     

细乳液法合成单核核壳结构氧化硅/聚苯乙烯复合微球

采用细乳液聚合法,以3-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)表面改性的直径50nm的氧化硅粒子为核,在乳化剂、助乳化剂、引发剂存在的情况下制备了小粒径、单核核壳结构氧化硅/聚苯乙烯纳米复合微球.研究表明,苯乙烯的浓度、超声细乳化时间,是制备这种小粒径、单分散、单核核壳结构的氧化硅/聚苯乙烯纳米复合微球的关键因素.透射电镜(TEM)的观察显示,在优化的实验条件下,可以制得平均粒径95nm,壳厚20nm,粒径均一、球形规整度较好、单核核壳结构的氧化硅/聚苯乙烯纳米复合微球.其平均粒径远低于用其它聚合方法制备的复合微球.     

聚丙烯腈基中孔碳的无机模板法制备和结构

采用模板法可制备孔径分布窄、中孔率和比表面积高的中孔碳。本文采用纳米氧化硅静电吸附十六烷基三甲基溴化铵(CTAB)及乳液聚合制备不同纳米氧化硅含量的聚丙烯腈/纳米氧化硅复合粒子,进一步通过高温碳化和氢氟酸刻蚀得到高纯度的中孔碳。发现当纳米氧化硅添加量不超过单体质量的50%时,纳米氧化硅主要以被聚合物包覆的形式存在,所制备的中孔碳的比表面积均大于800m2/g,孔径在5～10nm之间;随着纳米氧化硅/单体质量比从30%增加到60%,所制得的中孔碳的总孔容从1.111cm3/g增加至1.949cm3/g,中孔率从66.0%增至82.4%。结合中孔碳的形貌分析,认为纳米氧化硅的模板作用是形成中孔的主要因素。     

氧化硅包覆铁“壳/核”型纳米复合粒子的制备及其吸波特性研究

采用非平衡物理气相蒸发法在氢气氩气混合气氛下制备了氧化硅包覆铁“壳/核”型纳米复合粒子. 通过X射线衍射(XRD)、透射电子显微镜(TEM)和能谱分析(EDS)等方法表征了纳米复合粒子的相组分、结构以及颗粒形貌. 结果表明,制备的氧化硅包覆铁纳米复合粒子的尺寸在50nm左右,在铁纳米粒子的表面还出现了非晶态的氧化硅纳米棒,长度为150~200nm. 利用电磁参数模拟微波吸收特性得出,涂层厚度为1.79mm时,在15.4GHz频率处达到最小反射损耗值为-14.5dB,反射损耗在8~18GHz的频段低于-10dB,且损耗机制为自然共振.     

镍基-纳米SiO2复合镀层抗腐蚀性能的研究

制备了纳米氧化硅镍复合镀层材料,并利用静态浸泡法对纯镍镀层和由镀液中不同微粒含量制备的复合镀层样品的耐蚀性能进行了研究,讨论镀液中纳米微粒含量对镀层抗蚀性能的影响.并用扫描电镜观察镀层的表面形貌.     

纯无定形氧化硅纳米线热气相法制备及其光致发光性质

在氮气气氛和常压下,采用无金属催化的单步热气相法在单晶硅片上制备大量纯非晶氧化硅纳米线,采用SEM、HRTEM、EDS、XRD和荧光光谱（PL）研究氧化硅纳米线形貌、结构和光致发光性质,并分析其发光中心。结果表明1100℃可形成纳米棒,1200℃则获得光滑均匀纳米线,而1300℃得到的纳米线具有较多弯曲结构,氧化硅纳米线中硅氧原子比接近1∶2,且1300℃制得纳米线中氧含量略高于1200℃,氧化硅纳米线呈无定型态。SiO气化分解和氧化时在硅片上形成氧化硅纳米簇,成为无定形氧化硅纳米线生长的成核中心。氧化硅纳米线的两个光致发光峰值波长为467和364nm,其发光机制是纳米线生长过程中产生的不同点缺陷结构构成了蓝光和紫外光辐射复合中心。     

热塑性聚氨酯纳米粘土复合泡沫结构与性能的研究

要研究了纳米粘土含量对热塑性聚氨酯(TPU)复合泡沫的结构与性能的影响。通过扫描电镜(SEM)观察TPU泡沫的微孔结构发现:随着纳米粘土含量的增加,微孔的直径显著减小且数量明显增加。拉伸测试发现纳米粘土含量增加到5%(质量分数)时,TPU复合泡沫的力学性能增加了56.3%,而复合泡沫的密度却减小了12.5%。研究认为可以通过改变纳米填料的含量,来调节聚合物复合泡沫的微观结构和机械性能,这对微孔聚合物泡沫的工业生产有着重要的指导意义。     

提拉法制备二氧化硅陶瓷膜的形貌及性能

采用浸渍提拉工艺在复合镀镍的A3钢表面制备氧化硅陶瓷膜。借助扫描电镜观察陶瓷膜的微观形貌,应用电化学阻抗谱测试陶瓷膜的耐蚀性能并揭示耐蚀机理。用平面磨耗试验机测试了陶瓷膜的耐磨性能。结果表明:在500℃下烧结的氧化硅陶瓷膜为类似微裂纹镀铬的表面形貌;在400℃下烧结的氧化硅陶瓷膜与微孔镀铬的表面形貌相似;400℃及500℃烧结后形成无定形的SiO2陶瓷膜。阻抗较高的氧化硅陶瓷膜在3.5%(质量分数)NaCl溶液中的腐蚀过程为扩散控制,能明显抑制镀镍A3钢的腐蚀。氧化硅陶瓷膜降低了复合镀镍层的孔隙率。浸渍提拉成膜后膜层耐磨性能显著优于只复合镀镍的A3钢,浸渍提拉法能提高铁基体复合镀镍的耐磨性能。     

纳米氧化硅及其复合粉体的电磁参数的研究

以石蜡作为载体,制备了纳米氧化硅及其与乙炔碳黑混合的粉体材料,研究了该复合材料的电磁特性.结果表明,纳米氧化硅是一种电损耗材料,少量的纳米氧化硅添加到乙炔碳黑中,使乙炔碳黑的介电常数的虚部增加,实部降低,从而较大地提高了乙炔碳黑的介电损耗.     

高性能锂离子电池SiO/C/G复合负极材料研究

以一氧化硅、蔗糖及天然石墨为原料, 通过高能球磨和热解工艺制备了电化学性能优异的SiO/C/G复合负极材料。采用X射线衍射仪(XRD)和扫描电子显微镜(SEM)对复合材料的物相和形貌进行了表征。所制备的复合材料中, 纳米SiO颗粒(＜50 nm＝被无定形碳粘结并均匀分散在石墨鳞片上。电化学性能测试表明, 该复合材料100次循环后, 可逆容量高达1108.9 mAh/g, 容量保持率为103.8%。优异的电化学性能主要归因于纳米SiO颗粒在无定形碳基体中的均匀分布、无定形碳基体的缓冲作用和石墨相对复合材料导电性能的改善。     

Quenchability and Magnetic Properties of Nd_4Fe_(82)B_(14)

The glass forming ability (GFA), crystallization behaviour and magnetic properties of Nd4Fe82B14 produced by melt spinning were investigated. The experimental results show that the GFA is rather Strong; the crystals precipitation sequence is as follows: Am(amorphous)→Am'+bcc-Fe →Nd2Fe23B3+Fe23B6+bcc-Fe→Fe23B6+Fe3B+Nd2Fe14B+bcc-Fe→Fe3B+Nd2Fe14B+bcc-Fe. The magnetic properties after crystallization are not affected by the cooling rate and the best magnetic properties are Br=0.8436 T, Hcj=266.4 kA/m, (BH)max=48.08 kJ/m3.     

Formation of Omega-like Nanocrystalline in the Melt-Spun Nd_(85)Al_(15) Alloy by Phase Transformation

Microstructure and subsequent phase transformations on heating of the melt-spun Nd85Al15 alloy have been studied by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. The melt-spun Nd85Al15 alloy shows two-stage transformation processes as follows: amorphous+72 nm supersaturated bcc-Nd(AI) solid solution-7 nm omega-like phase-AlNd3+hexagonal Nd. The activation energies for the first and second transformation were found to be 100 kJ/mol and 188 kJ/mol, respectively. The formation mechanism of nanoscale omega-like phase is discussed.     

Formation of Omega—like Nanocrystalline in the Melt—Spun Nd85Al15 Alloy be Phase Transformation

Microstructure and subsequent phase transformations on heating of the melt-spun Nd85Al15 alloy have been studied by X-ray diffraction,transmission electron microscopy and differential scanning calorimetry.The melt-spun Nd85Al15 alloy shows two-stage transformation processes as follows:amorphous 72 nm supersaturated bcc-Nd(Al) solid solution→7 nm omega-like phase→AlNd3 hexagonal Nd.The activation energies for the first and second transformation were found to be 100kJ/mol and 188kJ/mol,respectively.The formation mechanism of nanoscale omega-like phase is discussed.     

纳米复合1.3μm光放大材料的荧光和吸收谱

纳米级掺稀土非氧化物团簇复合在氧化硅玻璃中,可以结合非氧化物玻璃和氧化物玻璃在光放大和化学、热力学、力学等方面各自的优点,提供可以应用于实用化1.3μm,宽带1.5μm和新发展的1.4μm光放大的新材料.在一种复合材料中,峰值位于1315nm的荧光峰及线型被证实与用来进行复合的掺稀土氟镓锆玻璃中的峰完全一致,而在复合材料中其荧光寿命较长.以Pr3+和Nd3+作为活性离子的复合材料的吸收谱线宽比Pr3+和Nd3+掺杂的ZBLAN的相应吸收谱线宽展宽最多达到10nm.复合材料的光谱性质有利于器件增益并放宽对泵浦光源的要求.     

Crystallization behavior of PZT film prepared by sol–gel route

The X-ray scattering measurements were used to investigate Pb(Zr,Ti)O₃ films prepared by sol–gel process. From analysis of specular and off-specular X-ray reflectivities, the morphology of nanoscale pores in Pb(Zr,Ti)O₃ film was determined by adjusting a model to the observed data. It is found that nanoscale pores in the films were closely attributed to the precursor with higher molar concentration. Furthermore, nanoscale pores present a certain degree of order in the direction normal to the film surface, which mainly distribute near the interface between films and substrate. The pores gradually close with annealing time increasing, and the closing process of the pores leads to pit formation in the film surface.     

Crystal growth and optical properties of the Nd doped LuF3 single crystals

Thirty millimeter diameter single crystal of Nd³⁺ doped LuF₃ was grown using LiF as solvent. The single phase crystallization was confirmed by the powder X-ray diffraction, and high structural perfection was demonstrated by X-ray rocking curve (XRC) measurements. FWHM of XRC for 220 reflection was 32 arcsec. No remarkable absorption due to unfavorable impurities was observed from optical absorption measurements in the VUV spectral region. The crystal showed the VUV luminescence peaking around 178 nm that is consistent with the 4f²5d-4f³ transition of Nd³⁺ ion. The luminescence intensity of Nd:LuF₃ under X-ray irradiation was significantly higher than that of reported VUV scintillators such as Nd:LaF₃ or Nd:LiLuF₄.     

Glass-Forming Ability for Nd_(70-x)Fe_(20)Al_(10)Y_x and Nd_(60-x)Fe_(30)Al_(10)Y_x Alloys

The glass-forming ability (GFA) of Nd70-xFe2oAl10Yx and Nd60-xFe30Al10Yx (0< x <15) alloys produced by Cu mold casting was investigated. Except Y=5 at. pct, bulk amorphous Nd70-xFe20Al10Yx alloys up to 2 mm in diameter were obtained. The GFA for Nd60-xFe30Al10Yx alloys, however, was found to decrease with increase of Y due to the increasing compositional deviation from the original eutectic point of Nd60Fe30Al10 alloy. The Nd60Fe20Al10Y10 and Nd60Fe30Al10 alloy exhibit the largest GFA and can be cast into bulk amorphous cylindrical specimens of 3 mm in diameter. The melting temperature or/and the reduced crystallization temperature is closely related to the GFA of Y-containing alloys. The bulk amorphous cylinder for the Nd55Fe20Al10Y15 alloy shows a distinct glass transition temperature and a wide supercooled liquid region before crystallization. The crystallization temperature, Tg, and the supercooled liquid region, TX, are 776 K and 58 K, respectively. The GFA and thermal stability of the Nd-Fe-AI-Y a     

Glass-Forming Ability for Nd70-xFe20AlioYx and Nd60-xFe30Al10Yx Alloys

The glass-forming ability (FGA) of Nd70-xFe20Al10Yx and Nd60-xFe30Al10Yx(0≤x≤15) alloys produced by Cu mold casting was investigated.Except Y=5 at.pct,bulk amorphous Nd70-xFe20Al10Yx alloys up to 2mm in diameter were obtained.The GFA for Nd60-xFe30Al10Yx alloys,however,was found to decrease with increase of Y due to the increasing compositional deviation from the original eutectic point of Nd60Fe30Al10 alloy.The Nd60Fe20Al10Y10 and Nd60Fe30Al10 alloy exhibit the largest GFA and can be cast into bulk amorphous cylindrical specimens of 3mmm in diameter.The melting temperature or /and the reduced crystallization temperature is closely related to the GFA of Y-containing alloys.The bulk amorphous c ylinder for the Nd55Fe20Al10Y15 alloy shows a distinct glass transition temperature and a wide supercooled liquid region before crystallization.The crystallization temperature,Tg,and the supercooled liquid region,ΔTx,are 776K and 58K,respectively,The GFA and thermal stability of the Nd-Fe-Al-Y alloys were discussed.     

Nanoprecipitation-assisted ion current oscillations

Nanoscale pores exhibit transport properties that are not seen in micrometre-scale pores, such as increased ionic concentrations inside the pore relative to the bulk solution, ionic selectivity and ionic rectification. These nanoscale effects are all caused by the presence of permanent surface charges on the walls of the pore. Here we report a new phenomenon in which the addition of small amounts of divalent cations to a buffered monovalent ionic solution results in an oscillating ionic current through a conical nanopore. This behaviour is caused by the transient formation and redissolution of nanoprecipitates, which temporarily block the ionic current through the pore. The frequency and character of ionic current instabilities are regulated by the potential across the membrane and the chemistry of the precipitate. We discuss how oscillating nanopores could be used as model systems for studying nonlinear electrochemical processes and the early stages of crystallization in sub-femtolitre volumes. Such nanopore systems might also form the basis for a stochastic sensor.     

Fe3B基纳米复合永磁材料的微结构和性能

利用差热(扫描)分析、X射线、透射电镜、振动样品磁强计研究了添加Co、Dy对Fe3B／Nd2Fe14B 纳米复合永磁材料的微结构和性能的影响．结果表明：添加适当的微量元素可以提高Nd4．5Fe77B18．5纳米复合永磁材料的内禀磁性，改进微结构，从而提高材料的永磁性能．在Nd4．5Fe77B18．5中添加1％-3％(原子分数)的Co、Dy明显地降低材料的晶化温度和最佳热处理温度、提高了2：14：1相的居里温度、改善了纳米复合永磁材料的微观结构，从而提高材料的永磁性能．与Nd4．5Fe77B18．5相比，Nd3．5Fe74Co3DylBl8.5的永磁性能为：Br=1.06T，jHc=328kA／m，(BH)max=108．9kJ／m^3，分别提高了26％，17％和104％．