镁合金微弧氧化工艺的研究进展

微弧氧化是一种在金属表面原位生长陶瓷膜层的表面新技术.该技术弥补了许多传统阳极氧化的不足之处,并且获得的膜层性能大幅提高.综述了镁合金微弧氧化技术的工艺原理、技术特点、成熟工艺、分类方法和发展趋势.     

基体对镁合金微弧氧化膜致密性的影响

采用致密化微弧氧化技术在Mg-Gd-Y,AZ 91D和ZM 6三种镁合金表面制备微弧氧化膜。通过电化学阻抗谱(EIS)、扫描电镜(SEM)等手段,比较了在三种镁合金表面制备的微弧氧化膜的致密性。三种镁合金微弧氧化膜的致密性依次为:Mg-Gd-Y>AZ 91D>ZM 6。可见,基体对微弧氧化膜具有重要的影响。该影响主要是由各合金上微弧氧化膜的PBR值(即氧化物与形成该氧化物所消耗的金属的体积比)不同所导致的,PBR值越高,微弧氧化膜越致密。     

镁合金表面着色技术

对镁合金表面着色技术进行了综述。分别介绍了喷涂着色、阳极氧化着色、金属涂层着色和微弧氧化着色技术。对镁合金微弧氧化着色的原理、着色陶瓷膜的生长特点、影响着色反应的因素进行了分析。指出了镁合金表面着色技术的发展方向。     

微弧氧化技术的研究现状

微弧氧化技术是一种直接在有色金属表面原位生长陶瓷膜的新技术。详细介绍了微弧氧化技术的发展历史和研究现状,微弧氧化的基本原理、基本工艺过程以及膜层的性能特点,并对这种陶瓷膜层的应用予以展望。     

镁合金微弧氧化技术的研究现状

微弧氧化技术是一种针对铝、钛、镁等阀金属及其合金进行表面陶瓷化的新技术。介绍了微弧氧化技术的原理、电解液体系及存在的问题,并对将来的发展趋势做了展望。     

基于MAO技术的阀金属功能膜层研究

根据多年来对微弧氧化工艺技术的研究与生产实践,总结出了铝、镁等阀金属及其合金表面不同功能膜层的制作方法。分析、讨论了不同电解液、电参数、时间及添加剂对微弧氧化过程、陶瓷膜层表面形貌、结构和性能的影响,并对我国微弧氧化技术的现状和国外的差别进行了说明,指出了我们的不足和今后的研究方向。     

镁合金表面处理的研究现状与展望

综述了镁合金表面处理技术的工艺进展,主要包括化学转化膜、阳极氧化、微弧氧化、金属涂层、离子注入等技术。分析了镁合金表面处理研究的发展趋势。     

不同基材微弧氧化无机陶瓷膜性能研究进展

微弧氧化技术是一种在金属及其合金表面通过微等离子体放电进行复杂的电化学、等离子化学和热化学过程,即在金属表面原位生长氧化物陶瓷膜的新技术。笔者介绍了不同基材采用微弧氧化制备陶瓷膜的性能研究进展,并指出了陶瓷膜技术发展方向。     

铝合金微弧氧化热力学机理及影响因素的分析

微弧氧化是一种新型的表面处理技术,能够在有色金属表面生成陶瓷膜.从微弧氧化的热力学机理出发,通过动力学和热力学能量平衡分析了α-Al2O4、γ-Al2O3转化,分析微弧氧化中相的转变同电流密度、氧化时间之间的关系.     

铝及其合金等离子微弧氧化技术

等离子微弧氧化是一种新兴的材料表面陶瓷化技术,利用该技术可在铝及其合金表面生成一层耐磨,耐蚀,耐高温以及电绝缘性能优异的陶瓷膜层,介绍了微弧氧化技术的发展及现状,基本原理,陶瓷膜的制备以及膜层结构及性能特点,并展望了其应用前景。     

钛合金微弧氧化技术的研究现状及展望

微孤氧化技术是一种在Al、Mg、Ti等有色金属及其舍金表面原位生长陶瓷氧化膜的新技术。利用该技术制成的氧化膜结构致密，结合强度高，具有优良的综合力学性能，近年来在该领域的研究一直较为活跃。本文综述了微孤氧化技术在国内外的研究现状，介绍了微弧氧化法的一般技术特点．概括了微孤氧化的制备方法、制备陶瓷膜层的影响因素和钛合金微孤氧化的应用领域，并展望了该技术的应用前景。     

Formation of anode oxide films on zirconium by means of the microspark anode oxidation in sodium silicate solutions

The microspark oxidation (MSO) (also known as microarc oxidation (MAO) or plasma electrolytic oxidation (PEO)) is one of the methods used for the formation of oxide coatings on valve metals. The main advantage of the MSO method, along with many others, consists in the simplicity of the technology of formation of films having a high adhesion to a metal substrate. The method enables one to obtain high-quality porous anode oxide films for different applications: antifriction, anticorrosion, for sensor materials, etc. In this work, the anode oxide films consisting of a mixture of three modifications of zirconia and a silica amorphous phase were formed on a zirconium foil from a sodium silicate aqueous solution by means of the MSO method.     

Effect of current density and polytetrafluoroethylene on the properties of micro-arc oxide coating of pure aluminum

Micro-arc oxidation (MAO) is a surface treatment technology that enhances the surface properties of valves by creating a ceramic oxide layer on the metal surface. The goal of this study is to investigate the influence of current density on the properties of aluminum coatings during preparation and to improve the tribological properties of MAO/PTFE self-lubricating films on the coating surface. The characterization of the coating was performed using X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectra, and energy dispersive spectroscopy. The roughness, hardness, and elastic modulus of the coatings were tested using atomic force microscopy and nanoindentation. Tribological experiments were conducted to evaluate the tribological properties of the coatings. The experimental results show that the friction coefficient (COF), roughness, hardness, and elastic modulus of the MAO coating increase with the increase of current density. Additionally, the friction coefficient of the MAO composite coating significantly decreases after the addition of polytetrafluoroethylene (PTFE), improving the service life and application range of the metal coating. These findings are expected to promote the development of valve metal in various application fields.     

Electrochemical behaviour of metal hexacyanoferrate converted to metal hydroxide films immobilized on indium tin oxide electrodes—Catalytic ability towards alcohol oxidation in alkaline medium

In this work, we demonstrate a simple method to modify indium tin oxide (ITO) electrodes in order to perform electro-catalytic oxidation of alcohols in alkaline medium. Metal hexacyanoferrate (MHCF) films such as nickel hexacyanoferrate (NiHCF) and copper hexacyanoferrate (CuHCF) were successfully immobilized on ITO electrodes using an electrochemical method. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the structural and morphological aspects of MHCF films. Cyclic voltammetry (CV) was used to study the redox properties and to determine the surface coverage of these films on ITO electrodes. Electrochemical potential cycling was carried out in alkaline medium in order to alter the chemical structure of these films and convert to their corresponding metal hydroxide films. SEM and XPS were performed to analyze the structure and morphology of metal hydroxide modified electrodes. Electro-catalytic oxidation ability of these films towards methanol and ethanol in alkaline medium was investigated using CV. From these studies we found that metal hydroxide modified electrodes show a better catalytic performance and good stability for methanol oxidation along with the alleviation of CO poisoning effect. We have obtained an anodic oxidation current density of ∼82 mA cm⁻² for methanol oxidation, which is at least 10 fold higher than that of any metal hydroxide modified electrodes reported till date. The onset potential for methanol oxidation is lowered by ∼200 mV compared to other chemically modified electrodes reported. A plausible mechanism was proposed for the alcohol oxidation based on the redox properties of these modified electrodes. The methodology adapted in this work does not contain costlier noble metals like platinum and ruthenium and is economically viable.     

Structural effects of nanocomposite films of amorphous carbon and metal deposited by pulsed-DC reactive magnetron sputtering

The relationship between metal-induced (W, Mo, Nb and Ti) structures and the surface properties of Me–DLC thin films is discussed. Nanocomposite films were deposited on c–Si wafers by pulsed-DC reactive magnetron sputtering controlling the gas ratio CH₄/Ar. The sputtering process of metals such as Ti, Nb and Mo (unlike the tungsten) in the presence of methane shows a low reactivity at low methane concentration. The deposition rate and the spatial distribution of sputtered material depend of Z-ratio of each metal. The surface contamination of metal targets by carbon, owing to methane dilution, limits the incorporation of metals into DLC films according to an exponential decay. Results of electron probe microanalysis and X-ray photoelectron spectroscopy indicate a C rich Me/C composition ratio for low relative methane flows. According to the depth profile by secondary ion mass spectrometry, the films are systematically homogeneous in depth, whereas at high carbon contents they exhibit a metal-rich interfacial layer on the substrate. Moreover, high resolution transmission electron microscopy has evidenced important structural modifications with respect to DLC standard films, with marked differences for each Me/C combination, providing nanodendritic, nanocrystallized or multilayered structures. These particular nanostructures favour the stress decrease and induce significant changes in the tribological characteristics of the films. This study shows the possibilities of controlling the amorphous carbon films structure and surface properties by introducing metal in the DLC matrix.     

Properties of SiO2 thin films prepared by anodic oxidation under UV illumination and rapid photothermal processing

Anodic oxidation under ultraviolet (UV) illumination and rapid photothermal processing technique used for high quality oxide preparation in terms of device surface passivation and gate or tunnel dielectrics are reported. A number of samples of SiO₂ thin films were prepared using this technique. It is shown that anodic oxidation under UV illumination followed by rapid photothermal processing (450 °C, 15 s) in the inert ambient yields the best optimization of the SiO₂ thin films properties. Avoiding high temperature process should result in a better performance of the semiconductor devices. Anodic oxidation under UV illumination at low temperature and post-oxidation photothermal processing can be a possible alternative to the furnace growth silicon oxide; not only because of the low temperature process, but also because this technology essential improves the oxides properties.     

铝合金表面扫描式微弧氧化成膜机理分析

以硅酸盐体系为电解液,利用扫描式微弧氧化（SMAO）方法在铝合金 2024 的表面成功制备出"蛇形"和"HIT"图案的陶瓷膜层。对扫描式和传统微弧氧化工艺进行了对比,采用扫描电镜和 X 射线衍射研究了 SMAO 陶瓷膜的结构和相组成。结果表明,与传统微弧氧化放电过程不同,扫描式微弧氧化在沿阴极前进的方向上依次分布着钝化区、阳极氧化区和微弧氧化区,没有观察到弧光放电。经过一次扫描生成的陶瓷膜厚度约为17 μm,膜层只有疏松层,且其中的α-Al₂O₃含量高于γ-Al₂O₃。对扫描式微弧氧化放电机理的分析表明,电场在阳极表面的梯度变化可能是同一时间内存在不同放电区域的原因,高达2 400 A/dm²的电流密度使扫描式微弧氧化具有高的成膜效率,同时也导致了疏松层内含有大量的α-Al₂O₃。     

镁基材料表面微弧氧化生物医用陶瓷涂层研究进展

利用微弧氧化技术在镁基材料表面原位生成陶瓷膜层,能显著增强镁基材料的耐磨性、耐腐性、生物相容性等表面性能,在医用镁基材料表面改性中具有广泛的应用前景.本文主要对镁基材料表面微弧氧化所用的电解液组成、陶瓷膜的结构组成、复合生物涂层及其生物相容性的研究现状进行了评述,并对今后的研究前景进行了展望.     

Thermal oxidation of gallium arsenide with transition metal nanolayers on the surface

The physicochemical features of the interaction between nanofilms of iron triad metals and the gallium arsenide surface during thermal oxidation are analyzed. The role of oxides formed upon oxidation of iron, cobalt, and nickel metal films in the course of thermal oxidation of gallium arsenide is demonstrated, and the influence of the metal deposition method on the kinetics of oxidation, the composition, and the properties of the prepared samples is determined. Schemes are proposed for the development of the oxidation processes under investigation with due regard for the chemical specific features of the iron triad metals and their compounds.