核微孔滤膜的制备及其应用

核微孔滤膜是利用重离子辐照高分子材料后，经化学蚀刻而制成。它具有真实的孔径和高选择过滤性能，因而得到广泛地应用。讨论了核微孔滤膜的制备原理、方法、特性及其应用。     

Kapitza resistance and thermal conductivity of Mylar at superfluid helium temperature

The Kapitza resistance and the thermal conductivity of type A Mylar sheets in the temperature range between 1.4 and 2.1 K have been determined. Four sheets with varying thickness from 37 μm to 255 μm, have been tested in steady-state condition. For a small temperature difference (10-30 mK) and heat flux density smaller than 30 Wm⁻², the total thermal resistance of the sheet is determined as a function of sheet thickness and bath temperature. The Kapitza resistance is given by R_K = (1.28 ± 0.08)T⁻³ × 10⁻³ Km² W⁻¹, and the thermal conductivity, κ = [(8.83 ± 0.75) + (11.73 ± 0.43) × T] × 10⁻³ Wm⁻¹ K⁻¹.     

大面积碳纳米管薄膜的低温制备与表征

采用研制的大体积射频等离子体红外加热化学气相沉积设备,在600℃的低温下,在5cm×5cm大的Ni片上生长出碳纳米管薄膜。扫描电镜(SEM)和透射电镜(TEM)观察显示,碳纳米管薄膜具有很好的均匀性,管径大约为70～90nm。随机地对样品的3个不同区域进行了场发射特性的测试,结果表明这种薄膜具有良好的场发射特性及一致性。开启电场约为2.4V/μm,在电场为6.6V/μm时的发射电流密度达到1635μA/cm2。实验结果表明在低温条件下,大面积生长场发射用碳纳米管薄膜是可行的。     

玻璃的辐照效应及耐辐照改性研究进展

航天科技、核医学、核能工业和绿色建筑的发展对使用在辐射环境中的玻璃提出了越来越高的要求。玻璃在辐射环境中会发生微观结构变化和宏观性质改变,耐辐照玻璃是一种在高能射线或粒子辐照后可见光区透过率下降较小,能保持物理化学性能稳定的特种玻璃。阐述了玻璃的辐照效应研究现状,介绍了玻璃耐辐照改性的研究进展及挑战,并提出了值得关注的新趋势。     

Effect of porous silicon stain etched on large area alkaline textured crystalline silicon solar cells

This work shows the effects of porous silicon stain etched on alkaline textured antireflection coatings of large area monocrystalline silicon solar cells. The texturization process has been produced by immersion of the silicon wafers in different carbonate-based solutions. The porous silicon layers were formed by stain etching in a HNO₃/HF aqueous solution before or after the texturization process. We study the effects of different alkaline and acidic solutions and the etching times on the solar cell parameters and the surface reflectance of the device. We have found that the average reflectance of the surface is lowered when the porous etching is combined with the texturization in the alkaline solution. However, the solar cell characteristics are not improved.     

天然沸石陶瓷分离膜的制备与表征

以天然沸石为原料,采用挤压成型的方法,制备出多孔陶瓷分离膜管.探讨并研究了沸石的反应烧结过程,以及烧成温度、保温时间对多孔陶瓷膜管微观结构的影响,测试了不同温度烧成样品的氮气通量、水通量和弯曲强度,讨论了抗热震性和骤冷温差之间的关系,并尝试对材料的上述性能进行了解释.     

BDAF-PMDA型聚酰亚胺炭膜的制备及其气体分离性能的研究

以2,2-双[4-(4-氨基苯氧基苯基)]六氟丙烷(BDAF)为二胺单体,均苯四酸二酐(PMDA)为二酐单体,采用两步法制备了BDAF-PMDA型聚酰亚胺,进一步高温热解制备炭膜.采用红外、热重、X射线衍射分析其结构变化,并测试炭膜对纯组分及混合气体的渗透性能和分离选择性.结果表明,BDAF-PMDA型炭膜具有较高的气体渗透性,在CO2/H2体系中可优先渗透CO2.提高炭化温度,炭膜孔径减小,气体的渗透性能降低,选择性提高,并使得BDAF-PMDA型炭膜的分离机理由表面扩散为主逐渐变为表面扩散和分子筛分共同控制.     

Growth and characterization of indium antimonide and gallium antimonide crystals

Indium antimonide and gallium antimonide were synthesized from the respective component elements using an indigenously fabricated synthesis unit. Bulk crystals of indium antimonide and gallium antimonide were grown using both the vertical and horizontal Bridgman techniques. Effect of ampoule shapes and diameters on the crystallinity and homogeneity was studied. The grown crystals were characterized using X-ray analysis, EDAX, chemical etching, Hall effect and conductivity measurements. In the case of gallium antimonide, effect of dopants (Te and In) on transport and photoluminescence properties was investigated.     

AZ91D镁合金超疏水膜层的制备及其表征

采用简单易行的化学刻蚀方法,通过硝酸刻蚀、化学镀银和硬脂酸自组装改性处理,在AZ91D镁合金表面上成功制备出了超疏水膜层,进一步解释了该制备工艺的化学反应机理。利用扫描电子显微镜和视频光学接触角测量仪对AZ91D镁合金表面超疏水膜层的微观形貌和润湿性能进行了表征,利用能谱仪和光谱仪测定了膜层的表面化学组成。结果显示,釆用上述方法处理后的AZ91D镁合金表面呈现出良好的疏水性,水滴在试样表面的表观接触角为153°,滚动角为4°。     

模拟太阳光下锗掺杂纳米TiO2对化学毒剂的降解性能

采用均匀沉淀法制备不同锗掺杂浓度的纳米二氧化钛(TiO₂); 为了研究掺杂浓度与粉体活性之间的关系, 针对化学毒剂(CWAs)模拟剂2-氯乙基乙基硫醚(2-CEES)和甲基膦酸二甲酯(DMMP)开展光催化消毒实验, 并用动力学方程拟合实验结果; 通过XRD、UV-Vis、BET、BJH、SEM和TEM等技术对样品进行表征, 分析锗掺杂对TiO₂结构及性能的影响; 综合考虑溶剂的毒性、挥发性、可燃性和溶解性等因素, 以氢氟醚(HFE)作为分散溶剂, 研究模拟太阳光下Ge-TiO₂和HFE混合体系对芥子气(HD)、梭曼(GD)和维埃克斯(VX)的消毒性能。结果表明: 适量锗掺杂不会改变纳米TiO₂的晶型结构, 可以减小晶粒尺寸, 增大比表面积, 增强光利用率, 提高消毒活性; 相较于直接使用粉体消毒, 混合体系的消毒效率明显提高; 在模拟太阳光下, 最佳锗掺杂浓度(6.24wt%)样品与HFE-458 (HCF₂CF₂CH₂OCF₂CF₂H)组成的混合体系与三种化学毒剂反应60 min的降解率分别为: HD 98.73%、GD 100%、VX 100%。     

Synthesis and characterization of large specific surface area nanostructured amorphous silica materials

Large specific surface area materials attract wide attention because of their applications in adsorption, catalysis, and nanotechnology. In the present study, we describe the synthesis and characterization of nanostructured amorphous silica materials. These materials were obtained by means of a modification of the Stobe-Fink-Bohn (SFB) method. The morphology and essential features of the synthesized materials have been studied using an automated surface area and pore size analyzer and scanning electron microscopy. The existence of a micro/mesoporous structure in the obtained materials has been established. It was also found that the obtained particle packing materials show large specific surface area up to 1,600 m2/g. (To our best knowledge, there is no any reported amorphous silica material with such a higher specific surface area.) The obtained materials could be useful in the manufacture of adsorbents, catalyst supports, and other nanotechnological applications.     

微波辐射合成共缩聚聚酰胺酸和聚酰亚胺

在微波辐射条件下,采用3,3’,4,4’-二苯酮四羧酸二酐(BTDA)、4,4’-二氨基二苯甲烷(MDA)和4,4’-二氨基二苯醚(ODA)为单体,N,N’-二甲基甲酰胺(DMF)为溶剂,低温合成一种共缩聚聚酰亚胺的前驱体聚酰胺酸(PAA),化学亚胺化脱水环化生成BTDA型共缩聚聚酰亚胺。通过红外光谱(FT-IR)、核磁共振(1H-NMR)、特性黏度([η])和热重分析(TG)等对聚合物进行了一系列的结构表征和性能测试。结果表明,微波辐射溶液聚合能够提高PAA的特性粘数及产率,微波的引入大大缩短了反应时间;FT-IR表明,在1779 cm-1和1717 cm-1处观察到聚酰亚胺特征峰;TG表明,PI在氮气中500℃左右开始降解,10%热失重温度(Td10%)为567℃。     

聚N-异丙基丙烯酰胺水凝胶的微波合成与性能

以水为溶剂,N-异丙基丙烯酰胺(NIPAM)为单体,N,N-亚甲基双丙烯酰胺(Bis)为交联剂,分别通过微波合成法和水浴加热法制备了聚N-异丙基丙烯酰胺(PNIPAM)水凝胶,研究了交联剂浓度、反应时间、反应温度等对反应的影响,及PNIPAM水凝胶在不同温度和pH值下的溶胀性变化。研究结果表明,与水浴加热法相比,微波合成法缩短了反应时间,从10h缩减至1h左右;适当延长反应时间和提升反应温度有利于提高单体转化率。微波法合成PNIPAM的最佳条件为:H2O为溶剂,100℃~110℃反应40 min~60 min,交联剂m(Bis)/m(NIPAM)=5/100,单体转化率97%~98%。而且,微波合成法制备的水凝胶具有更显著的温度和pH敏感性能。     

SiC及a-SiC：H薄膜的辐照及其进展

SiC是一种宽带隙半导体材料,在高温,高频在,大功率,光电子及抗辐射等方面具有巨大的应用潜力,介绍了国外对该材料及其薄膜进行辐照的一些结果,并指出开展SiC及其薄膜辐照效应研究的重要意义,预测了其发展方向和应用前景。     

超声辐照条件下HCl掺杂聚苯胺纳米棒的结构和性能

在超声辐照条件下,以HCl为掺杂剂、(NH4)2S2O8为氧化剂,通过溶液聚合得到了HCl掺杂聚苯胺(PA-NI)纳米棒.采用傅里叶变换红外光谱(FTIR)、透射电子显微镜(TEM)、X-射线衍射(XRD)、四电极电导率仪、热重分析(TGA)和电化学工作站对材料的结构与性能进行研究.研究结果表明,超声辐照条件下HCl掺杂PANI具有较高的掺杂程度和结构规整度,形成直径为50～65 nm左右的纳米棒状结构.与传统方法相比,超声辐照法所得材料的热稳定性在270～500℃有明显上升,室温电导率升至0.25 s/cm,并具有较好的电容行为和较高的电化学活性.     

He+辐照对CLAM钢焊缝微观组织和性能的影响

在室温下用强度为70 ke V的He⁺辐照CLAM钢焊缝,使用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和连续刚度纳米压痕技术(CSM)对其表征,研究了He⁺辐照对CLAM钢焊缝的微观组织和性能的影响。结果表明,随辐照剂量的增大焊缝表面黑色孔洞的尺寸增大、密度提高;辐照剂量为1×10¹⁷ions·cm^-2时,在两种焊缝中形成的位错环的尺寸分别约为18.97 nm、15.73 nm,数密度分别约为2.24×10²¹m^-3、1.78×10²¹m^-3,氦泡引起的辐照肿胀率分别约为1.7%和0.4%;辐照缺陷(位错环、氦泡)导致的辐照硬化率分别为49.0%和29.9%。与焊态焊缝相比,调质处理态焊缝的辐照损伤较弱,在一定程度上表明经调质处理后焊缝的抗辐照性能有所提高。     

轨道不平顺检测中数字补偿滤波器的设计及仿真

轨道不平顺是影响列车安全舒适的主要因素，轨检车可实时准确的检测出轨道不平顺状态；但车速的变化会使传感器信号发生畸变和衰减，使分析数据失真。为了消除车速的影响，分析了轨检系统中数字补偿滤波器的理论及设计方法，最后进行了CCS5000仿真验证。结果表明，数字补偿滤波器能够消除前端有用信号的衰减，且可达到较高的精度。     

Synthesis and characterization of large area well-aligned carbon nanotubes by ECR-CVD without substrate bias

Large area, well-aligned carbon nanotubes (CNTs) were synthesized on porous silicon by electron cyclotron resonance chemical vapor deposition (ECR-CVD). No bias was applied on the substrate in this experiment. CH₄ and H₂ were used as source gases and Fe₃O₄ nanoparticles as the catalyst. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), and Raman spectrum were used to evaluate the structure and composition. The results show that these CNTs have varying outer diameters from 10 to 90 nm and uniform length over 10 μm. They display hollow tubular and chain structures. The possible formation mechanism of aligned CNTs is discussed.