流延法制备SOFC阳极支撑体基片

系统地研究了流延法制备SOFC阳极支撑体基片过程中影响流延浆料粘度和素坯质量的主要因素, 分析了球磨时间、有机混合溶剂类型、分散剂添加量、增塑剂/粘结剂比例(R)等参数以及除泡工艺对浆料流变性能的影响. 研究发现: 混合溶剂乙醇/二甲苯(体积比1:1)对粉料的湿润性能最好, 粉体的悬浮性能和浆料流变性能最佳; 分散剂添加量为1.8wt%时, 浆料的粘度最低; 研磨时间为24h制备的浆料流变性接近最佳状态; 浆料的粘度随R值的增大而急剧减小, 当R为1时粘度达到最佳值, 流变性能得到明显改善; 少量的除泡剂和真空搅拌对消除浆料制备过程中所产生的气泡极为有效.     

AAO模板快速制备方法探究

为了快速制备出高度有序且孔径可调控的AAO(阳极氧化铝)模板应用于工业生产,通过改进传统的两步阳极氧化法,采用逐步提高电解液浓度的硬氧氧化法制备了AAO模板,并确定了最佳制备工艺为初始电解液浓度0.15mol/L,添加电解液浓度0.40mol/L,温度保持在5℃左右,无水乙醇添加比例为1:1,从而使铝片的击穿电压从40V上升到130V左右(模板面积1.5cm×4.5cm),采用DimensionEdge型号的原子力显微镜(AFM)对多孔氧化铝模板进行了表征。结果表明:未经退火处理的铝片,也可以制备出高度有序的AAO模板,但其粗糙度略有增加,并与在高压条件下二次氧化、三次氧化、四次氧化制备AAO模板进行了比较,发现二次氧化制备的AAO模板有序度、孔径、孔间距均优于三次、四次氧化法。     

电化学阳极氧化条件对阵列多孔硅的影响

采用电化学阳极氧化法,将预光刻图案的p型硅片制备成阵列多孔硅.讨论电化学阳极氧化条件对阵列多孔硅形貌的影响.结果表明:随着HF浓度、电流密度、阳极氧化时间的增大,阵列多孔硅的孔深逐渐加大;当HF:C2H5OH:H2O(体积比)为1:1:1～1:2:5,电流密度为1.56mA/cm2,阳极氧化时间为3h时,制备出的阵列多孔硅具有比较规整的阵列孔,并且孔深能够达到50pm;表面活性剂对阵列孔的形成有很大影响,加入表面活性剂后形成的孔才具有一定的规整性以及深宽比.     

管状阳极氧化铝模板的表面氧化应力分析及其应用研究

通过对高纯铝片预制铝管分别进行"外表面阳极氧化"(外氧化)和"内表面阳极氧化"(内氧化)制备了管状多孔氧化铝模板(AAO),考察了氧化过程中Al/Al2O3界面的应力影响。实验直观表明,"外氧化"过程中Al/Al2O3界面产生拉伸应力易导致管状模板产生轴向裂纹;而"内氧化"过程中Al/Al2O3界面产生压缩应力使管状模板更加紧密而不易破裂。研究结果表明,Al/Al2O3界面上拉伸应力的有效释放是获得无裂纹管状阳极氧化铝模板的关键。最后,利用管状氧化铝模板制备了放射状Cu纳米线阵列,并对其在膜渗透方面的应用进行了初步尝试。     

乙醇/水混合溶剂中一维ZnO晶须的制备与表征

以乙醇/水作溶剂,氯化锌(ZnCl2)和氢氧化钠(NaOH)为原料,采用简单的低温陈化法制备出不同长径比的一维(1-D)ZnO晶须.用X射线衍射仪(XRD),扫描电子显微镜(SEM)及高分辨透射电镜(HRTEM)等分别对晶须的形貌和结构进行表征.考察了乙醇与水的体积比对晶须粒径及长径比的影响,结果表明,随混合溶剂中乙醇含量升高,晶须粒径逐渐减小.同时,从晶体生长的角度对乙醇影响氧化锌晶体生长的作用机理进行了初步探讨,认为乙醇通过"表面-溶剂作用"吸附在ZnO晶体表面,使其各晶面的生长速率受到不同程度的抑制,从而达到减小晶须粒径的目的.     

草酸/磷酸混合介质制备高质量阳极氧化铝模板

以草酸为主导酸、磷酸为辅助酸的混合介质作为电解液,采用不对称二次氧化法制备阳极氧化铝模板(AAO模板),通过调节电压、介质配比和酸的浓度等方式研究其生长机制及优化条件.利用扫描电子显微镜(SEM)和电流监测装置对得到的AAO模板进行表征,结果表明在低压(40 V)、较低浓度草酸条件下,适量掺杂磷酸可以提升模板阵列有序性、孔洞规则性及孔径;在高压(80 V)下制备出表面具有V字型结构孔洞的模板,当混合介质中主导酸和辅助酸各自适配电压与施加电压差值比为其混合体积比倒数时所制备的模板质量最优,且随电压增大V字型结构的孔径增大,但辅助酸掺杂量不宜过高.本研究可为采用多元介质制备大孔径优质AAO模板提供参考.     

三维网络结构氧化铜纳米线锂离子电池负极材料的制备和性能研究

通过阳极氧化法和后退火处理在铜箔上合成了三维网络结构氧化铜纳米线,将其作为负极材料制备了无需添加粘结剂的锂离子电池。研究了恒压氧化时间对材料形貌和电化学性能的影响。在1C的倍率下,氧化1000 s制备的CuO纳米线表现出最高的1172 mAh/g首圈放电比容量和594 mAh/g的可逆比容量,500圈循环可逆比容量为607.6 mAh/g,可逆容量保留率为102.3%。交联的三维网络结构CuO纳米线相互支撑,提供稳定的结构,有效缓解了CuO纳米线作为锂离子电池负极材料中的体积膨胀问题,表现出了优异的倍率性能和循环寿命。     

乳化交联法制备壳聚糖微球粘连原因分析

乳化交联法是制备壳聚糖微球常用的工艺，但在制备过程中，常出现微球产物粘连的现象。分析了搅拌速度、油水体积比、表面活性剂添加量和交联剂用量等影响微球粘连的因素，优化出了分散性好，粒度均匀的壳聚糖微球制备工艺参数。结果表明，搅拌速度〉350r／min，油水体积比〉2．5，表面活性剂span80用量为水相的20％时，可获得分散性好的壳聚糖微球，微球的粒径可以控制在1～5μm之间。     

结构调制型氧化铝模板的制备及表征

采用两种不同方法制备了结构调制的多孔氧化铝(AAO)模板,一种是磷酸扩孔法,另一种是非对称阳极氧化法。磷酸扩孔法是根据传统有序氧化条件,在模板二次阳极氧化后,用磷酸对已形成的孔道进行扩孔,然后再进行第三次阳极氧化;非对称阳极氧化法是在第一次氧化后形成的有序凹痕上,在始终保持氧化电压与第一次氧化时相同,同时确保相邻两次氧化在不同类型电解液中进行的条件下,制备出孔间距相同、孔径不同的有序结构调制的AAO模板。这些方法扩展了在给定电解液中制备AAO模板的孔径,从而实现了AAO模板的结构调制。     

高长径比TiO2纳米管阵列的调控制备及其光阳极性能

采用较高粘度的有机溶液作为阳极氧化电解质溶剂制备了TiO₂纳米管阵列. 通过探讨阳极氧化工艺参数对纳米管形貌的影响, 研究出高长径比TiO₂纳米管阵列的制备工艺, 同时对TiO₂纳米管作为染料敏化太阳能电池光阳极的光电性能进行了测试, 并讨论了TiO₂纳米管的形貌对电池性能的影响. 结果表明：提高氧化电压和延长时间有利于获得高长径比纳米管, 在含0.5wt%NH₄F乙二醇电解质中50V氧化17h可制备出长径比为313.6的TiO₂纳米管阵列. TiO₂纳米管(在含0.5wt%NH4F乙二醇电解质中40V氧化13h)作为染料敏化太阳能电池光阳极可得到开路电压为0.723V、短路电流为2.15mA/cm²的光电性能.     

The electrical breakdown during anodizing of high purity aluminium in borate solutions

High resolution scanning electron microscopy of the surfaces of aluminium specimens supporting barrier-type anodic films and transmission electron microscopy of the stripped films have been employed to gain further insight into the mechanism of the electrical breakdown during anodizing of aluminium in borate solutions. Particular attention has been paid to the following aspects of the phenomenon: (1) the sites at which breakdown initiates, (2) the development of breakdown and (3) the structure and morphology of the films after the breakdown events. The observations indicate that the breakdown is possibly of a thermal nature and is triggered by local heating effects caused by highly localized processes taking place at flaws during anodizing, including the possibility of initial electron avalanching.     

Prozess zur Anodisierung von Aluminiumbändern mit hoher elektrischer Durchschlagsspannung

Process for anodizing of aluminum stripes with high electrical breakdown voltage The Aim of the research was to develop an anodizing process for generating a high breakdown voltage on aluminum stripes in the shortest processing time possible. In order to vary process parameters in a wide range, a flexible discontinuous anodizing laboratory device was designed in cooperation with Steinert Elektromagnetbau GmbH Köln. By means of the liquid contact method, conditions equal to non‐solid contact anodizing of aluminum stripes in continuous laboratory devices were simulated. The research was focused on the development of the current pulse shape. The results show that the highest possible breakdown voltages can be achieved in a short processing time using suitable electrical parameters (current pulse shape) and the appropriate post‐treatment. The films generated by the new technology (current pulse shape referred to as “TUCAL”) reveal a higher pore density than conventional layers. This results in a higher ductility (less tendency for cracking).     

Synthesis and characterization of CuO nanoparticles using strong base electrolyte through electrochemical discharge process

In the present study, cupric oxide (CuO) nanoparticles were synthesized by electrochemical discharge process using strong base electrolytes. The experiments were carried out separately using NaOH and KOH electrolytes. The mass output rate and the crystal size were obtained with variation of the rotation speed of magnetic stirrer for both types of electrolytes. The mass output rate of CuO nanoparticles increased with the increase in the speed of rotation, and, after an optimum speed, it started decreasing. However, the size of the particles reduced with the increase of the rotation speed. The crystal plane of the obtained CuO nanoparticles was similar for both the electrolytes whereas the yield of nanoparticles was higher in KOH as compared with NaOH under the same experiment conditions. In this set of experiments, the maximum output rates obtained were 21.66 mg h^?1 for NaOH and 24.66 mg h^?1 for KOH at 200 rpm for a single discharge arrangement. The average crystal size of CuO particles obtained was in the range of 13–18 nm for KOH electrolyte and 15–20 nm for NaOH electrolyte. Scanning electron microscopy images revealed that flower-like and caddice clew-shaped CuO nanocrystalline particles were synthesized by the electrochemical discharge process. Fourier transform infrared spectrum showed that the CuO nanoparticles have a pure and monolithic phase. UV–vis–NIR spectroscopy was used to monitor oxidation course of Cu → CuO and the band gap energy was measured as 2 and 2.6 eV for CuO nanoparticle synthesized in NaOH and KOH solutions, respectively.     

电流密度对AZ91D镁合金阳极氧化膜表面形貌及粘接性能的影响

采用恒电流方式在AZ91D镁合金表面制备多孔阳极氧化膜。通过电压-时间曲线研究了电流密度对氧化行为的影响。采用SEM、单板拉剪试验研究了电流密度对氧化膜表面形貌及拉伸强度的影响。结果表明,电流密度不影响击穿电压及临界电压的大小。随着电流密度增加,电压达到击穿电压及临界电压的时间缩短,氧化膜孔隙率及拉伸强度均先增加后减小,当电流密度为10 mA/cm~2时拉伸强度最大,可达到22.40 MPa。     

Photolytic breakdown of fullerene C60 cages in an aqueous suspension

Fullerene C60, a class of carbon nanomaterials, is widely used and is likely to reach the environment. The degradation and transformation of C60 aqueous suspensions exposed to simulated sunlight were studied. C60 aqueous suspensions prepared by stirring pristine C60 in water under sunlight exposure undergo breakdown with formation of a mixture of compounds with unknown chemical structure. The mass and infrared spectrometric analysis of the breakdown products shows the presence of broken C60 cages, as well as of oxygen and hydrogen atoms in their structure. The presence of oxygen in the breakdown products indicates a possible interaction of C60 molecule with oxygen from the air as well as with water. Interaction with water could also explain the presence of H atoms in the breakdown products. This demonstrates that fullerenes C60 are not stable in the environment and that the breakdown products should be considered when evaluating the environmental impact of fullerenes C60.     

Morphology Controlling of the Ultrafine Cerium Dioxide (CeO2) Precursor

The synthesis of ultrafine cerium dioxide precursor via homogeneous precipitation was studied. Mixed aqueous solution of anhydrous cerium nitrate and urea was first heated to 85℃ for 2 h, and the prepared suspension was then aged at room temperature for various periods of time. White precipitate was finally collected by centrifuging and washed with distilled water and anhydrous ethanol. The obtained cerium dioxide (CeO2) precursor was observed with SEM. It was found that the morphology and size of the precursor were strongly affected by aging time and stirring conditions (with or without stirring). The precipitated fine spherical particles of the precursor changed their shape from ellipse to slice or directly to slice. Fine spherical monodispersed (300 nm) precursor powders could be obtained by controlling the aging time. Stirring the solution also could change the reaction process and thus the morphology and size of the precursor were changed.     

Synthesis of Nanocrystalline Barium Ferrite in Ethanol/Water Media

Nanocrystalline particles of barium ferrite magnetic material have been prepared by co-precipitation route using aqueous and non-aqueous solutions of iron and barium chlorides with a Fe/Ba molar ratio of 11 and subsequent drying-annealing treatment.Water and ethanol/water mixture with volume ratio of 3:1 were used as solvents in the process.Coprecipitated powders were annealed at various temperatures for 1 h.FTIR(Fourier transform infrared spectroscopy),XRD(X-ray diffraction),DTA/TGA(differential thermal an...     

Ibuprofen agglomerates preparation by phase separation

The compression ability and dissolution rate of ibuprofen are poor. There are many processes to optimize these properties through adapted formulations. However, it would be more satisfactory to obtain directly during the crystallization step crystalline particles that can be directly compressed and quickly dissolved. This was the aim of this work. Ibuprofen spherical agglomerates were obtained using a very simple method based on the difference of solubility of ibuprofen in ethanol and in water. By cooling down an ibuprofen-saturated solution in an ethanol/water 50/50 mixture from 60°C to room temperature under stirring, a phase separation occurs. Ibuprofen crystallizes in separated water droplets. After separation by sieving and drying, spherical agglomerates were obtained. A study of the physical properties of ibuprofen agglomerates was carried out using electron scanning microscopy and X-ray powder diffraction. The compression ability was tested using an instrumented tablet machine, and the dissolution rate was measured using continuous flow cells. An improvement in compression and dissolution properties of the spherical agglomerates produced was observed. The process of crystallization in a separated dispersed phase could be envisaged each time a drug exhibits opposite solubilities in two miscible solvents.     

Preparation and characterization of plasticized polymer electrolytes based on the PVdF-HFP copolymer for lithium/sulfur battery

PVdF-TG-LiX polymer electrolytes comprised of polyvinylidene fluoride (PVdF)-hexafluoropropylene (HFP) copolymer, tetra(ethylene glycol) dimethyl ether as plasticizer, LiCF₃SO₃, LiBF₄ and LiPF₆ as lithium salt and acetone as solvent have been prepared by solvent casting of slurry that mixed PVdF-HFP copolymer with acetone and salt using a ball-milling technique, which was performed for 2 and 12 h with a ball-to-material ratio of 400:1, and their electrochemical and thermal properties were studied. The ball-milled PVdF-TG-LiX polymer electrolytes have higher ionic conductivity as well as lower glass transition temperature and melting points than the magnetically stirred one. The PVdF-TG-LiPF₆ polymer electrolytes prepared by ball-milling, for, 12 h, in particular, resulted in a maximum value in the ionic conductivity, which was 4.99×10^–4 S cm^–1 at room temperature. The ball-milled PVdF-TG-LiX polymer electrolytes were introduced into Li/S cells with sulfur as cathode and lithium as the anode. The first specific discharge capacities with discharge rate of 0.14 mA cm^–2 at room temperature were about 575 and 765 mA h g–cathode^–1 for magnetic stirring and 12 h ball milling.