多孔金属在催化中的应用

概述了多孔金属材料在催化领域的应用，从作为催化膜反应器和催化剂载体两个方面进行了总结，以期为扩展多孔金属在催化中的进一步应用提供线索。     

Ti—Al金属间化合物多孔材料的研究进展

Ti—Al金属间化合物多孔材料兼备陶瓷和金属多孔材料的性能优势,为具有很大发展潜力的新型无机多孔材料。目前,对于Ti—Al金属间化合物多孔材料的研究包括以下3个方面：反应合成Ti—Al金属间化合物多孔材料的制备及孔结构形成过程和机理;偏扩散-反应合成-烧结制备的Ti-Al金属间化合物多孔材料的物理、化学性能;偏扩散-反应合成Ti-Al金属间化合物多孔材料的应用及其潜力。Ti-Al金属间化合物多孔材料包括多孔体、多孔膜和多孔纸型膜等多种形式;Ti—AI金属间化合物多孔材料的性能主要包括膨胀特性、孔结构性能、抗环境腐蚀性能及焊接性能;Ti—Al金属间化合物多孔材料的现有应用范围主要包括过程工业中流体介质的过滤分离净化,以及化学工业中复合钯膜的支撑体。     

多孔材料透过性能的表征

透过性能对用于过滤分离、流体混合、布气分流等方面的多孔材料是一项十分关键的质量指标。主要介绍了多孔材料透过性能的表征方式，包括流体流动的基本概念、层流条件下流体的透过性能表征、多孔材料透过性能的综合表征、气体透过多孔材料时渗透系数的具体表征等方面。     

功能性多孔氧化铝膜的应用研究进展

多孔氧化铝膜以其有序的孔排列、可控的孔径和优良的结构形态在其功能性应用中具有独特的优越性,近年来引起了人们的广泛关注,并取得了较大的进展.对多孔性氧化铝膜在催化、磁性材料、光学及光电元件、分离、抗菌和润滑等方面的功能性应用进行了介绍,并对多孔氧化铝膜功能性应用的前景进行了展望.     

多孔材料孔率的测定方法

孔率是多孔材料的关键指标，是多孔材料若干性能最主要的决定性因素。简单介绍了测定多孔材料孔率的几种常用方法，包括显微分析法、质量．体积直接计算法、浸泡介质法、漂浮法和压汞法等。     

Fe3Al多孔材料预氧化性能研究

以Cr改性的Fe3Al预合金粉末为原料,采用粉末冶金方法制备Fe3Al多孔材料,研究氧化温度、时间、降温速度对Fe3Al多孔材料氧化膜性能的影响。结果表明:Fe3Al多孔材料的氧化增重随温度的升高而增大,氧化动力学遵循四次方规律,在800℃的大气中氧化9h,氧化膜已完全将烧结颈覆盖,晶粒细小;随着温度的升高和时间的延长,晶粒变得粗大;900℃氧化5h,膜层已出现裂纹;而降温速度对氧化增重的影响不大,也没有出现由于热膨胀不匹配而产生的裂纹。     

脱合金法制备纳米多孔金属的研究进展

纳米多孔金属具有独特的物理、化学、力学性能,具有极大的科学与工程应用潜力.脱合金法是制备此类材料的有效技术,是实现其应用的关键.本文概述了脱合金法制备纳米多孔金属的原理,并从脱合金法制备纳米多孔金属的材料体系、初始材料的制备工艺以及纳米多孔金属的性能三方面综述了脱合金法制备纳米多孔金属的研究进展.     

不同膜胞尺寸铝多孔氧化膜的制备

采用在磷酸及草酸溶液中加入添加剂的方法制备了铝多孔氧化膜,借助扫描电镜分析了多孔氧化膜的微观结构,讨论了不同组成电解质溶液对铝多孔氧化膜膜胞尺寸的影响。结果表明,通过在磷酸和草酸溶液中添加少量添加剂,可以在60-500V的氧化电压内获得多孔氧化膜。得到膜胞尺寸最大可达1．3μm;膜胞尺寸随着氧化电压的升高呈线性升高趋势...     

粉末冶金技术制备金属多孔材料研究进展

金属多孔材料既有金属的性质,又因为孔的存在,而具有一系列功能特性,诸如密度低、比表面积大、机械强度高、通透性好等,是一种性能优异的多功能工程材料,因而在工程中得到广泛的应用.本文阐述了粉末冶金技术制备金属多孔材料的最新研究进展,主要分析了生物金属多孔材料、形状记忆合金多孔材料、多孔钨电极、多孔不锈钢和多孔铜的制备及研究进展.     

镍质多孔材料的电镀修饰

电镀生成多孔膜是可行的,研究结果表明:溶液pH值、极距、添加剂、Ni2 浓度、电镀时间、电流密度对膜的透气度和最大孔径影响显著,温度的影响也较大.正交试验的结果得出了以上七个因素对电镀效果的影响次序.根据正交试验结果,综合考虑产品的透气度和最大孔径,本文确定最佳条件为:pH值4.5～5,极距30mm.Ni2 浓度20g/L,添加剂浓度0.15g/L,电流密度300A/m2,电镀时间20mim,温度40℃.在此条件下可制得孔径小于0.32μm,透气度为3×10.m/Pa·h的膜.     

氧化铝纳米有序阵列模板的制备工艺及应用

采用二次阳极氧化的方法,制备出高度有序的氧化铝有序阵列模板.研究了热处理工艺、电解液浓度、温度等因素对氧化铝有序阵列模板孔洞有序性的影响,结合扫描电镜和透射电镜对其结构、形貌进行观察和表征,讨论了有序孔洞形核与长大、自组织生长导致有序性的机理.回顾和总结了近年来有关阳极氧化铝模板的制备方法和国内外有关阳极氧化铝模板的应用进展.     

Sol–gel derived films in meso-porous matrices: porous silicon,anodic alumina and artificial opals

Processing of the sol–gel derived films doped with the lanthanides onto generally available microelectronic materials-like porous silicon (po-Si) and porous anodic alumina is considered as a low-cost method of fabricating the thin luminescent films. The origin of 1.53 μm emission from Er-doped xerogels fabricated onto micro-, meso- and macro-porous silicon is discussed. Further, porous anodic alumina, exhibiting regular pore morphology was shown to be an effective template for fabricating the luminescent xerogels. Finally, application of sol–gel process for synthesis the 3D colloidal photonic crystals is discussed.     

Influence of copper on the morphology of porous anodic alumina

Sputtering-deposited Al-Cu alloy layers and an Al-Cu/Al bi-layer are used to investigate the influences of copper on the morphology of porous anodic alumina films formed galvanostatically in either sulphuric or phosphoric acid electrolyte. The results reveal development of an irregular morphology of pores during anodizing of the alloy layers, contrasting with the linear porosity of films formed on aluminium. Further, the rates of film growth and alloy consumption are relatively low, since oxygen is generated following enrichment of copper in the alloy and incorporation of copper species into the anodic film. The linear morphology is re-established following depletion of the copper in the bi-layer and at the same time, film growth accelerates as oxygen evolution diminishes. The irregular pore morphology is considered to arise from stress-driven pore development influenced by effects of oxygen bubbles within the anodic alumina.     

Pore development in anodic alumina in sulphuric acid and borax electrolytes

The formation of porous anodic films on an Al-3.5 at.%W alloy is compared in sulphuric acid and borax electrolytes in order to investigate pore development processes. The findings disclose that for anodizing in sulphuric acid, the pores develop mainly due to the influences of field-induced plasticity of the film and growth stresses; in borax, field-assisted dissolution dominates. The films formed in sulphuric acid are consequently much thicker than the layer of oxidized alloy and tungsten species are retained in the film. In contrast, with borax, the films and oxidized alloy layers are of similar thickness and tungsten species are lost to the electrolyte. Efficiencies of film growth are also significantly different, about 65% in sulphuric acid and about 52% in borax. The retention of tungsten species during anodizing in sulphuric acid is due to the localization of tungsten in the inner regions of the barrier layer and cell walls, with a layer of anodic alumina separating the tungsten-containing regions from the electrolyte. For borax, the tungsten is distributed more uniformly through the film material, enabling loss of tungsten species to the electrolyte from the pore base.     

多孔阳极氧化铝膜EIS阻抗谱研究

为进一步研究多孔氧化铝膜的结构和性能,采用电化学综合分析仪测量并分析不同工艺条件下所制备的阳极氧化铝膜的电化学交流阻抗EIS图谱,建立了不同工艺条件下制备的阳极氧化铝膜的等效电路模型.结果表明:在草酸、磷酸电解液中形成的阳极氧化铝膜是多孔双层膜.在硫酸电解液中形成的直流阳极氧化铝膜的等效电路中无多孔层信息.采用直流、交流和脉冲不同电源方式,在不同电解液中制备的氧化铝膜的EIS阻抗谱各不相同,所模拟的等效电路也有所不同.     

有序多孔氧化铝模板及 ZnO 沉积膜的制备与表征

采用二次阳极氧化法制备有序多孔氧化铝模板(AAO),探讨了氧化时间、磷酸溶液浸泡后处理对氧化铝表面形貌的影响。以AAO为模板沉积ZnO薄膜,通过SEM,XRD,EDS,AFM等技术对氧化铝模板及ZnO薄膜进行表征,结果表明,有序多孔层为非晶态氧化铝。研究了以AAO为模板沉积ZnO薄膜作光阳极的染料敏化太阳电池的光电转换性能,得出其转换效率为0.34%。     

The behaviour of chromium during anodizing of Al–Cr alloys

The anodic oxidation of dilute Al–Cr alloys, containing 0.8 and 1.7 at% Cr, has been investigated in order to understand the oxidation behaviour of the alloying element and its influences on the film composition and morphology. The alloys reveal two stages of oxidation: an initial stage, in which only aluminium atoms are oxidized to form a chromium-free anodic alumina film, and a subsequent stage, in which both aluminium and chromium are oxidized, in their approximate alloy proportions, with generation of a chromium-contaminated anodic alumina film. In the first stage, chromium is enriched in a thin layer of alloy, immediately beneath the anodic film, to an amount corresponding to a layer of average thickness 1.5 nm and of average composition, Al–20 at% Cr. Following the oxidation of chromium, oxygen is produced electrochemically within the film at or near the alloy/film interface, probably associated with the development of chromium-rich clusters in the enriched alloy layer and, subsequently, formation of semiconducting chromium-rich oxide. Thus, the film material formed at the alloy/film interface by inward migration of O^2- ions contains many oxygen-filled bubbles with associated high pressures. The chromium species present in the film migrate outward more slowly than Al³⁺ ions. Hence, a layer of chromium-free anodic alumina, which thickens as the film grows, is maintained adjacent to the film/electrolyte interface.     

以溶胶-凝胶法在多孔不锈钢基体上附载Al2O3膜

以SB粉为原料,采用溶胶-凝胶法在多孔不锈钢基体上附载一层多孔Al2O3膜.考查了溶胶浓度,酸量,添加剂量及浸渍次数对溶胶及成膜性质的影响,SEM检测结果表明,多孔氧化铝膜完整且没有明显裂纹.     

不同电解温度下阳极氧化铝薄膜纳米孔的自组织过程

研究温度对阳极氧化铝薄膜纳米孔自组织过程的影响.使用环境扫描电镜(ESEM)研究了铝试样在硫酸、草酸、磷酸溶液中,于不同电解温度下阳极氧化形成的氧化铝薄膜形貌.通过分析阳极氧化时电流密度与时间关系曲线,研究了温度对阳极氧化铝薄膜纳米孔自组织过程的影响.提出降低电解温度能够缩短纳米孔自组织过程的时间,是由于降低电解温度增大了纳米孔内表面的表面张力.并且提出在不同的电解质溶液中,电解温度对纳米孔自组织过程的影响程度不同,电解温度对纳米孔自组织过程的影响以在硫酸溶液中最敏感,草酸次之,在磷酸溶液中的影响最小.     

AC PEO of aluminium with porous alumina precursor films

The effect of the composition, morphology and thickness of pre-formed porous anodic films on the subsequent formation of coatings on aluminium by plasma electrolytic oxidation is investigated. The pre-formed films, of a wide range of thickness, are shown to be incorporated into the coatings. Further, an increased thickness of the film is revealed as beneficial to the establishment of a microarc regime that is favourable for the formation of the coatings. The anodic alumina undergoes melting under the microdischarges, which changes the cellular film morphology and reduces the concentration of anion contaminants.