阳极氧化法制备氧化铝纳米线薄膜及其生成机理研究

研究了一种简单新颖的制备氧化铝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(AAO)的工艺为基础,在草酸电解液中将AAO孔壁溶解形成氧化铝纳米线,均匀覆盖在AAO有序孔道的上方,得到一种特殊结构的纳米线薄膜.对实验产物纳米线的形貌、结构及成分进行了表征分析,并探讨了氧化铝纳米线薄膜的生成机理.     

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。     

控电位法制备CdSe纳米线阵列及其性能研究

以SeO2为硒源,以阳极氧化铝为模板,采用电化学方法对SeO2在碱性电解液中的还原过程进行了分析,确定了控电位制备CdSe纳米线的沉积电位和镀液组成,并分析了其沉积机理。在此基础上,以阳极氧化铝为模板,通过控电位法成功获得CdSe纳米线阵列。采用扫描电子显微镜、透射电子显微镜和X-射线衍射对所制备的材料进行了形貌和结构表征。扫描电镜形貌分析表明,CdSe纳米线阵列高度有序、直径均一;直径约100 nm,与模板孔径一致。X-射线衍射测试表明,所制得的CdSe纳米线为立方晶型。光电性能测试表明,CdSe纳米线阵列电极的开路电位差值为324.8 mV,高于CdSe薄膜(125.5 mV);光催化降解罗丹明B测试表明,5 h后,CdSe纳米线的降解率达94.29%,强于CdSe薄膜(52.03%)。     

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。     

高度有序多孔阳极氧化铝模板制备工艺研究

在酸性电解液中,用二次阳极氧化法制备得到了高度有序的多孔阳极氧化铝(PAA)模板。采用金相显微镜观察了铝箔退火前后的表面形貌,并结合扫描电镜对多孔氧化铝薄膜的结构进行了表征。研究表明,高度有序多孔阳极氧化铝膜的制备依赖于铝箔是否经过预处理、氧化电压的大小、温度的稳定性和电解液的选择等。     

铝阳极氧化法制备Al2O3纳米线

采用二次铝阳极氧化法在草酸体系中制备多孔铝阳极氧化膜,用逆电剥离技术将氧化膜从铝基体上剥离：经超声清洗后,放入磷酸溶液中去除阻挡层,使纳米孔贯通。再将膜放入c=1mol／L的NaOH溶液和w=6％的铬酸、w=1．8％的磷酸混合溶液中进行溶解,可获得Al2O3纳米线。纳米线长度为40μm,与模板厚度一致,直径为10～20nm.通孔前后铝阳极氧化膜的形貌由SEM进行表征,纳米线的形貌由SEM和TEM表征．此外,本文还结合模板在溶解过程中的实验现象,对Al2O3纳米线的形成机理进行了初步分析。     

模板法交流电沉积铜纳米线阵列及其表征

先通过二次阳极氧化法制备多孔阳极氧化铝膜模板,再采用交流电沉积法将Cu金属填入模板的纳米孔洞中得到铜纳米线阵列。分别采用扫描电镜、透射电镜和X射线衍射仪对Cu纳米线阵列的形貌和晶体结构进行表征。结果表明,多孔氧化铝模板的孔洞排布致密、均匀而有序。交流电沉积所得Cu纳米线为单晶结构,直径为60~90 nm,长度为0.5~4.0μm。     

阳极氧化铝模板有序度影响因素的研究

在酸性电解液中,用阳极氧化法制备了多孔阳极氧化铝模板。用金相显微镜观察了铝箔退火前后的表面形貌,并结合扫描电镜对多孔氧化铝薄膜进行了形貌观察和表征。研究了影响多孔氧化铝模板孔有序性(分布均匀,大小一致)的关键性因素。实验结果表明,多孔阳极氧化铝膜结构特性依赖于铝箔预处理、氧化电压、电解液类型和温度等的选择。     

一维阵列银纳米线制备及其微观结构

通过直流电沉积,以多孔阳极氧化铝膜(Al2O3/ Al)为模板,在纳米孔道内进行限域生长,制备了金属Ag纳米线.用X射线衍射光谱(XRD)、扫描电镜(SEM)、原子力显微镜(AFM)等检测手段对产物进行了表征.结果表明,Ag纳米线具有面心立方晶体结构,阵列排列整齐,长度超过5μm,单体纳米线的直径约为70 nm,与所用模板的孔径相当.     

强碱-阳极氧化法处理Ti片制备TiO_2薄膜的研究

本文利用强碱-阳极氧化法对钛片进行改性,制备TiO2薄膜;用扫描电镜（SEM）、X射线光电子能谱（XPS）考察了不同电解液浓度下氧化电压对TiO2氧化膜形貌及组成的影响。结果发现,在本实验条件下,该法制得的氧化膜是由三种钛氧化物组成的,主要成分是TiO2,此外还有低价钛氧化物Ti2O3及TiO;氧化电压的不同会对薄膜形貌产生重要的影响,当氧化电压较高时,氧化膜的厚度比较厚且致密;钛表面生成氧化膜大致过程可概括为：Ti→TiO→Ti2O3→TiO2,其中TiO转为为TiO2的几率依靠电势的大小及氧化时间的长短。     

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.     

氧化钛纳米线阵列的溶胶凝胶模板合成与表征

采用二次阳极氧化工艺制备了高度规则排列的多孔氧化铝（PAA）模板,并利用模板法与溶胶-凝胶法结合的模板组装技术制备了氧化钛纳米线阵列,得到了直径在50 nm左右,线间距约为50 nm的纳米线阵列.研究了模板组装过程不同压力条件对溶胶向模板孔洞中填充度的影响,发现在一定的负压条件下,有利于PAA孔中气体的排出,得到高的溶胶填充度,进而制备出高质量的纳米线阵列.分别通过SEM及XRD技术表征了PAA模板及纳米线的形貌及相结构.SEM观察发现纳米线彼此平行,表面光洁,不存在龟裂,纳米线的长度和直径与所使用模板的厚度和直径一致,表明纳米线的生长受控于模板;XRD分析表明模板为单一的θ-Al₂O₃晶型,纳米线为锐钛矿型TiO₂.     

氧化铝模板中Ag纳米线阵列的选择性生长

利用Ag离子与Br离子之间的化学沉积作用在孔隙中充满明胶的阳极氧化铝（AAO）模板中制备了AgBr/AAO纳米介孔复合材料.材料选择性曝光后,利用原位显影液对其进行化学显影,在AAO模板中选择性得到Ag纳米线阵列.实验结果表明：Ag纳米线是连续的、致密的,且具有多晶结构,充满了曝光部分的模板孔隙.本文还对影响Ag纳米线选择性生长的因素进行了简单讨论.     

Fabrication of cobalt nanowires from mixture of 1-ethyl-3-methylimidazolium chloride ionic liquid and ethylene glycol using porous anodic alumina template

Porous anodic alumina template is synthesized by electrochemical anodization of aluminum and used to grow cobalt nanowires. The cobalt nanowires produced by direct current electrodeposition are characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction and physical property measurement system. Test results indicate that the average diameter of cobalt nanowires is about 45 nm, which is generally the same as the pore diameter of porous anodic alumina template, and the cobalt nanowires electrodeposited from mixture of 1-ethyl-3-methylimidazolium chloride ionic liquid and ethylene glycol have a smoother surface and better magnetic properties than cobalt nanowires electrodeposited from aqueous solution, and they show a better squareness. Therefore it can be concluded that the cobalt nanowires electrodeposited from mixture of 1-ethyl-3-methylimidazolium chloride ionic liquid and ethylene glycol using porous anodic alumina template can be used as a perpendicular magnetic recording film.     

Mechanism of one-step voltage pulse detachment of porous anodic alumina membranes

The mechanism for one-step detachment of porous anodic alumina (PAA) membranes by using an electrochemical voltage pulse technique is systematically studied. Electrochemical oxidation of pretreated aluminum foil results in a thin oxide layer called barrier layer alumina (BLA) between the formed PAA and the Al substrate. Achievement of through-hole PAA membranes requires electrolytes of highly concentrated perchloric acid containing biacetyl and a short detaching pulse voltage of 5-10 V higher than the film forming potential. The influence of the PAA forming potential, voltage pulse height (0-10 V), and the nature of electrolytes on the efficiency of detachment have been systematically investigated. The successful detachment of the PAA could only be achieved with systems giving appropriate transient current upon application of an optimal voltage pulse. Based on the experimental results and the electropolishing mechanism of aluminum, a two-step detachment process of PAA freestanding films is proposed. In this mechanism, the detachment of PAA film from the aluminum substrate upon application of a short voltage pulse is followed by a pores-opening process. The present mechanism is promising for preparation of freestanding PAA films with various pores sizes, which are important for nanomaterial synthesis.     

Fabrication and characterization of alumina fiber by anodic oxidation and chemical dissolution processes

Alumina fiber was fabricated by an anodic oxidation process from pure aluminum or a chemical dissolution process from porous alumina. In the experiments, porous alumina layer was firstly formed on the surface of pure aluminum by anodic oxidation process in phosphoric acid electrolyte. The alumina fiber was obtained by either further anodic oxidation process or a chemical dissolution process from the porous alumina layer. The thickness of the porous alumina layer, the diameter and wall thickness of the pores in the porous alumina layer, and the length and diameter of the obtained alumina fiber were examined. The formation mechanism of the alumina fiber was discussed.     

Modification of alumina bubbles with ammonium aluminum sulphate

Ammonium aluminum sulphate was introduced to modify alumina bubbles by the wet chemical method. Distribution of ammonium aluminum sulphate, in situ decomposition characteristics, microstructure and mechanical properties of the modified alumina bubbles were investigated by SEM, XRD, BET and by a purposely designed experimental device for the measurement of compressive resistance. Experimental results showed that an ammonium aluminum sulphate thin film was formed on the surface of the alumina bubbles, at the same time, ammonium aluminum sulphate also infiltrated into the flaws and cavities of the alumina bubbles. After heat-treated at 900 °C, the ammonium aluminum sulphate on the alumina bubbles could be in situ decomposed to γ-Al₂O₃ with high activity. The compressive resistance of the modified alumina bubbles was enhanced from 15.6N to 38.7N after heat-treatment at 1700 °C for 2 h.     

A study of the adhesion of polyethylene to porous alumina films using the scanning electron microscope

An adhesive bond was formed by sintering low-density polyethylene onto aluminum with a porous anodic film. The topography of the polymer surface in contact with the anodized aluminum was studied in a scanning electron microscope, having removed the aluminum and alumina by dissolution in aqueous sodium hydroxide. The surface of the polymer appeared very rough with large projections of various forms, all of which were many times larger than the pores revealed in the anodic films by transmission electron microscopy. These projections are shown to consist, most probably, of “stacks” or “tufts” of much smaller polyethylene fibers, each of which had entered a pore in the anodic film. Thus, the scanning electron-microscopic investigation confirms the keying mechanism for the adhesionof polyethylene to porous anodic films on aluminum proposed in an earlier paper.     

Porous Alumina Films with Width-Controllable Alumina Stripes

Porous alumina films had been fabricated by anodizing from aluminum films after an electropolishing procedure. Alumina stripes without pores can be distinguished on the surface of the porous alumina films. The width of the alumina stripes increases proportionally with the anodizing voltage. And the pores tend to be initiated close to the alumina stripes. These phenomena can be ascribed to the electric field distribution in the alumina barrier layer caused by the geometric structure of the aluminum surface.