多孔铝阳极氧化膜的制备及膜孔的影响因素

采用阳极氧化法制备铝氧化膜,探讨了前处理、电解液组成、电解液浓度以及氧化电压等参数对氧化过程的影响.实验结果表明:前处理对氧化膜的质量有较大影响;适当比例的磷酸和草酸的混合酸制备的多孔膜质量最佳,在一定范围内,提高阳极氧化电压可使膜的孔密度减小,孔径增大,膜的有序性增加.两步阳极氧化法制备的多孔氧化铝模板的有序性优于一步氧化法.     

高度有序的多孔型铝阳极氧化膜的制备

以硫酸为电解液研究了多孔阳极氧化铝膜的制备,并采用场发射扫描电子显微镜对多孔氧化铝膜的形貌进行表征.结果表明:氧化电压在24～26 V时能够得到孔径为25～30 nm的多孔氧化铝膜.在不同电压下进行阳极氧化时,多孔氧化铝形成过程均经历了阻挡层形成、多孔层萌生及多孔层稳定生长三个阶段,但多孔层萌生及稳定生长的电流密度随氧化电压的升高而增加.当氧化时间为6h时氧化膜厚度达到最大值38nm.对多孔氧化铝膜进行XPS分析表明,氧化铝膜的主要成分为非晶态Al2O3.     

制备工艺条件对铝阳极氧化膜膜厚度的影响

采用阳极氧化法制备了Al2O3-Al一体型多孔氧化铝膜,考查了制备工艺条件对氧化膜厚度的影响。结果表明,随着氧化电流密度、氧化时间、电解液浓度等参数的增加,氧化膜厚度亦随之增加。SEM研究结果表明,氧化膜由内层致密的阻挡层和外层的多孔层两部分组成。     

影响多孔阳极氧化铝膜结构特性因素的研究

酸性电解液中采用电化学方法可在铝表面形成多孔阳极氧化铝膜。研究了影响膜孔径和膜厚的关键因素,包括电解液、氧化电压、温度和时间。此外,通过X-射线衍射和扫描电镜,分析了形成氧化膜的微观形貌和晶体结构。实验结果表明多孔阳极氧化铝膜结构特性依赖于采用的氧化条件、电解液、氧化时间和电压的选择。     

阳极氧化制备多孔氧化铝膜的研究

在高纯度的铝片上 ,采用阳极氧化的方法制备多孔氧化铝膜 ,可以采用硫酸、草酸、磷酸作为电解液 ,电解液的种类将影响氧化铝膜上孔洞的孔径大小 ,同时电解液的浓度 (硫酸 2 % -2 0 %、草酸 1% -5 %、磷酸 10 % -30 % )、氧化电压 (硫酸电解液电压 10～ 30V ,磷酸电解液电压 30～ 80V ,草酸电解液电压 2 0～ 10 0V ,)、氧化时间等都会影响氧化铝孔膜的形态。     

多孔阳极氧化铝模板制备工艺的研究

以硫酸溶液为电解液,采用二次阳极氧化工艺制备高度有序的多孔阳极氧化铝模板.研究了电解液浓度、阳极氧化电压和阳极氧化温度对多孔阳极氧化铝模板形貌、孔径和孔间距的影响,并以高氯酸和丙酮的混合溶液为电解液,利用第三次阳极氧化,一步实现了多孔阳极氧化铝膜的通孔剥离,获得具有较大面积、韧性较好的通孔多孔阳极氧化铝模板.     

阳极氧化法制备纳米孔径的多孔Al2O3膜

本文采用阳极氧化法制备多孔Al2O3陶瓷膜，研究了电流密度、氧化时间和电解液对铝表面原位生长多孔氧化铝膜的影响。应用扫描电镜(SEM)，能谱仪(EDS)和X射线衍射(XRD)等手段分析研究了氧化铝膜的相结构和表面形貌。     

多孔氧化铝模板的制备及形成过程研究

在直流恒电压条件下,以草酸为电解液制备了多孔氧化铝模板。采用扫描电子显微镜对多孔氧化铝模板的形貌进行表征。氧化铝模板的厚度测量表明,当氧化时间为6h时,氧化膜厚度达到最大值35.0mm。根据氧化过程的j-t曲线研究了多孔氧化铝模板的形成过程。     

规整填料型加氢脱硫催化剂的制备及性能评价

用电化学方法制备多孔氧化铝膜,并负载Mo-Co活性组分制得了金属支撑-多孔层规整填料型加氢催化剂。采用BET和SEM技术表征了多孔性氧化铝膜的物理结构,并考察了电解及后处理条件的影响。结果表明,电解液浓度、氧化时间、水封时间、水封温度等对多孔氧化铝膜的比表面积影响显著。采用二次氧化的方法,在质量分数为4%的草酸电解液、氧化时间1 h、80℃水封3 h条件下,所制备的多孔氧化铝膜具有相对较大的比表面积。汽油重馏分加氢反应结果表明该类催化剂具有较高的催化活性和选择性。     

阳极氧化电压对多孔氧化铝膜生长过程的影响

以草酸溶液为电解质,采用两步电化学阳极氧化法制备了氧化铝有序多孔膜,研究了阳极氧化电压对多孔膜生长过程及形貌的影响. 结果表明,电流密度、生长速率及孔径、孔间距随电压的升高而增大,而膨胀因子与电压呈线性关系. 氧化铝膜的孔隙率保持在12%左右,与电压基本无关.     

多孔氧化铝膜厚度公式的推导

近年来随着纳米技术的发展,对制备纳米材料的氧化铝多孔膜厚度的要求越来越高。目前,只能通过仪器测量出它的厚度,在制备的过程中却得不到很好的控制,使其应用受到了阻碍。针对这一问题,采用“固定变量”和“归纳猜想”相结合的方法,综合其各种影响因素,推导出了多孔氧化铝膜厚度的经验公式。经验证,由该公式计算得到的理论值与实际测量值吻合得较好。且在一定条件下,可以根据实际需要来调整各个影响因子的值,从而得到所需膜的厚度;同时,还可以根据实验条件算出所制得膜的厚度。     

铬酸浓度对铝阳极氧化多孔膜阻挡层形成过程的影响

对铝在不同浓度的铬酸中阳极氧化多孔膜阻挡层形成过程进行研究,随着铬酸浓度的增加,阻挡层形成电流密度增加,形成阻挡层所需的时间减少,阻挡层厚主变薄。这些现象可归结为阻挡层形成时应力集中的结果。     

Al2O3纳米线薄膜的制备及其生成机理研究

研究了一种简单新颖的制备Al2O3纳米线薄膜的电化学方法。以阳极氧化法在高纯铝片表面制备多孔阳极氧化铝的工艺为基础,在草酸电解液中通过一次阳极氧化过程,将阳极氧化铝孔壁溶解形成Al2O3纳米线,均匀覆盖在阳极氧化铝有序孔道的上方,得到一种特殊结构的纳米线薄膜。使用扫描电镜、高分辨透射电镜和X-射线能谱仪对纳米线的形貌、结构及成分进行了表征分析。并结合扫描电镜对不同反应时间长度的产物形貌来观察纳米线的生成过程。探讨了Al2O3纳米线薄膜的生成机理。     

铝在铬酸中高电压阳极氧化的研究

采用扫描电镜和透射电镜观察了铝在铬酸溶液中,高电压阳极氧化所形成多孔膜的孔结构。借助Ｘ射线衍射技术分析了多孔膜的晶体结构,以及阳极氧化条件对多孔膜结构的影响。     

Fabrication of Densely Packed AlN Nanowires by a Chemical Conversion of Al2O3 Nanowires Based on Porous Anodic Alumina Film

Porous alumina film on aluminum with gel-like pore wall was prepared by a two-step anodization of aluminum, and the corresponding gel-like porous film was etched in diluted NaOH solution to produce alumina nanowires in the form of densely packed alignment. The resultant alumina nanowires were reacted with NH₃ and evaporated aluminum at an elevated temperature to be converted into densely packed aluminum nitride (AlN) nanowires. The AlN nanowires have a diameter of 15–20 nm larger than that of the alumina nanowires due to the supplement of the additional evaporated aluminum. The results suggest that it might be possible to prepare other aluminum compound nanowires through similar process.     

阳极氧化法制备透明氧化铝薄膜的研究

以铝箔为阳极,石墨为阴极,草酸为电解液,采用二次阳极氧化法制备透明氧化铝薄膜。采用金相显微镜观察一次阳极氧化和二次阳极氧化后氧化铝薄膜的表面形貌,并用X射线衍射仪对氧化铝薄膜结构进行表征。结果表明,二次阳极氧化工艺对氧化铝薄膜的质量有重要的影响。采用退火-除油-浸蚀-电化学抛光-一次阳极氧化-二次阳极氧化工艺,并严格控制工艺参数,可以制备结构良好的透明氧化铝薄膜,且氧化铝薄膜是非晶态结构。     

Application of the seed-film method for the preparation of structured molecular sieve catalysts

The seed-film method has been applied for the preparation of various materials of potential interest as structured molecular sieve catalysts. The method has proven to be very flexible and allows for the reproducible preparation of a number of molecular sieve–substrate combinations as well as the control of the materials’ properties of importance in catalytic applications such as zeolite loading, film thickness, film density and crystal orientation. The preparation of thin molecular sieve films on ceramic foams, -alumina pellets and porous alumina supports as well as various metal surfaces is described. The preparation of zoned coatings with a compositional gradient is also discussed.     

Preparation of PdO-decorated NiO porous film on ceramic substrate for highly selective and sensitive H2S detection

This work is to develop high-performance thin film gas sensors on the alumina ceramic substrate. Here, porous NiO films of about 2 μm were obtained by the simple electrochemical deposition technique. The NiO gas sensing thin films obtained by the in-situ growth overcomes the disadvantages of great thickness, material agglomeration, and uneven size of the conventional device structure. The films exhibit good uniformity, consistency, and reproducibility. The composition of the films and their porous morphological characteristics were demonstrated by SEM, XRD, AFM, and XPS characterization. The doping of PdO significantly enhanced the sensitivity and specificity selection of the NiO films for H₂S gas. 2 wt% PdO/NiO thin film sensor exhibited a high response (515.27) and fast dynamic process at 155 °C for 10 ppm H₂S. The outstanding gas-sensing performance of the thin film sensor is due to the doping of PdO and the porous structure of the film.     

In situ spectroscopic ellipsometric study of porous alumina film dissolution

Porous alumina films have been synthesised by anodisation of high purity aluminium in 0.4 M phosphoric acid at constant current density. The dissolution process of those coatings in 2 M phosphoric acid has been investigated by in situ spectroscopic ellipsometry (SE) combined with electrochemical measurements. A sharp drop of the open current potential is observed due to film removal. The dissolution time depends on total barrier layer thickness. Those results are confirmed by SE measurements. A three layer optical model has been used to interpret SE spectra. During the dissolution process, the porous top layer has a quasi-constant thickness, whereas porosity increases significantly. The dissolution proceeds within the pores. Only the thickness of pure alumina barrier layer (upper part) decreases during the dissolution process whereas the interface barrier layer (lower part) does not change.     

Fabrication and structural control of anodic alumina films with inverted cone porous structure using multi-step anodizing

Porous anodic alumina (PAA) film has recently attracted much attention as a key material for the fabrication of various nanostructures. In this study, a multi-step anodization and leaching process was employed to produce three-dimensional nanometer scale structured film. During the leaching process, the porous alumina film was dipped in phosphoric acid solution for pore widening. Each anodization process was followed by this leaching process. This method produced alumina film with multi-step structure. Meanwhile, with five-step film production, the structure showed inverted cone structure. We produced the low aspect ratio pores of this structure, which would be applicable for fabrications of nanomaterials. In addition, the aspect ratio was controlled by changing the anodization duration.