Effect of cerium addition on microstructure and texture of aluminum foil for electrolytic capacitors

Anode foil of aluminum electrolytic capacitor,which requires large surface area for high capacitance,were prepared by rolling,annealing and electrochemical etching.Effects of cerium addition on the capacitance of aluminum electrolytic capacitors were investigated.Microstructure of the aluminum foil surface was observed by optical microscopy(OM) and scanning electron microscopy(SEM).Electron back scattered diffraction(EBSD) was also employed to reveal texture evolvement of cold-rolled aluminum foil after ann...

Evolution of recrystallization textures in high voltage aluminum capacitor foils

The evolution of recrystallization textures in high voltage aluminum capacitor foils which are produced with a high level of cold reduction was tracked by analysis of microstructure and crystallographic texture. The results show that the deformation textures are mainly composed of S orientation, Cu orientation and a little B s orientation. During the low temperature stages of final annealing, the iron precipitates first along the sub grain boundaries, and the Fe concentration in the matrix becomes low. Then, the cube grains nucleate preferably into the sub grains. At high temperature stages, the cube nuclei can grow preferably because of their 40°<111> orientation relationship to the S orientation, the main component of the rolling texture. Finally, the cube texture is sharply strong and the R orientation is very weak in the foils.

Distribution of Microelements and Their Influence on the Corrosion Behavior of Aluminum Foil

The distribution of microelement Fe, Si, Cu and Mg in the surface layer of aluminum foil annealed at 300℃ and 500℃ were determined by secondary ion mass spectrometer. The corrosion structure produced by electrochemical etching was also observed. It was found that the Mg concentration at external surface was increased exponentially over the fourth degree and promoted by higher annealing temperature, which will increase the number of corrosion pits inside the large grains, and therefore the specific capacity of the foils for electrolytic capacitors. The similar effects of microelement Fe, Si and Cu were not so strong.

Effect of trace Sn on corrosion behaviors of high voltage anode aluminum foil

The cube texture and the surface corrosion structure of aluminum anode foil for high voltage electrolytic capacitor containing trace Sn were investigated based on quantitative texture analysis and microstructure observation under SEM. High volume fraction of cube texture over 95% and obviously higher specific capacity are obtained in the foils with less than 0.002% Sn. It is indicated that the corrosion behavior of trace Sn on aluminum surface is similar with that of Pb. Higher content of Sn over 0.002% reduces the cube texture component and therefore the specific capacity. Sn, as an eco-friendly microelement, can be applied to replace Pb in improving the homogenous pitting behaviors of high voltage aluminum foils.

Effect of Trace Sn on Pitting Behaviors of High Voltage Anode Aluminum Foil

The effect of trace Sn on the pitting morphology of high voltage anode aluminum foils was investigated. The distributions of microelement Sn, Fe, Si, Cu and Mg in the surface layer of aluminum foils with different Sn content were determined by using a secondary ion mass spectrometer. It was found that the micro-alloyed Sn is enriched at the external surface. The mechanism of pitting behavior of trace Sn on aluminum surface is similar with that of lead. Enrichment of Sn in the surface layer provides large numbers of sites for initiation of pitting corrosion, while pitting sites appeared relatively inhomogenously in the foils without Sn. Sn, as an eco-friendly microelement, can be applied to replace Pb in improving the homogenous pitting behaviors of high voltage aluminum foils, in which the volume fraction of cube texture is not reduced.

Effect of tunnel structure on the specific capacitance of etched aluminum foil

The morphology of etched aluminum foil was observed using scanning electron microscopy, which led to the establishment of a cylindrical model and two merged models, considering the fixed weight loss of etching. The maximum of specific capacitance and the cor- responding optimum values for tunnel sizes at various anodization voltages were predicted. The increased size distribution and taper of tun- nels were demonstrated to decrease the specific capacitance, whereas the addition of polymeric additive into the ttmnel widening solution was demonstrated to increase the capacitance. The formation of merged tunnels on the etched aluminum surface, irrespective of the presence of row-merged tunnels or cluster-merged tunnels, resulted in a dramatic decrease in the specific capacitance. It is concluded that, enhancing the uniformity of turmel size and distribution and avoiding the formation of merged tunnels are the effective approach to achieving the higher capacitance for the tunnel etched and formed aluminum foil.

磷酸三甲酯添加剂对铝箔腐蚀隧道孔形成的影响

目前,铝电解电容器通过电化学腐蚀发孔工艺来制造阳极铝箔,以获得高面密度的隧道孔,从而提升比表面积和比电容。然而,腐蚀发孔过程中出现严重的孔并和隧道孔分布不均匀的问题,严重限制了阳极铝箔的比电容提升。为解决该问题,通过在腐蚀发孔溶液中添加磷酸三甲酯(TMP)来调控隧道孔的形核位点。适宜浓度的TMP一方面能够降低腐蚀发孔溶液的表面张力,改善阳极铝箔和腐蚀发孔溶液的润湿性;另一方面,润湿性的改善直接导致铝箔表面均匀溶解的阻力降低,从而显著降低隧道孔形核的阻力,最终改善腐蚀铝箔的比表面积。通过形貌表征和统计分析发现,在添加质量分数1%TMP的腐蚀发孔溶液中,铝箔腐蚀发孔时的隧道孔分布均匀性得到了显著改善,相较于没有添加TMP的空白样品,比表面积提升了约50%。本项研究为制造高性能的阳极铝箔提供了一种新的思路和方法。

高压直流输电换流阀阻尼电容器故障机理分析和防范对策研究

详细论述了高压直流输电换流阀阻尼电容器的电气工作原理以及不同类型阻尼电容器的工艺结构和电气特性,对该电容器运行中出现故障的机理进行了分析,通过仿真及大量冲击放电试验结果的对比,说明大电流冲击下不同类型阻尼电容器元件结构及材料对其电气参数的影响,得出金属铝箔式电容器耐电流冲击特性更优,更适合作为高压直流输电换流阀阻尼电容器的结论。

铝电解电容器阳极箔表面阵列微孔的激光打孔装置

伴随着电子技术的兴起与发展,电子器件的装配密度和集成性进一步提高,同时这也对铝电解电容器的性能提出了新的要求。传统工艺多采用电化学腐蚀进行制备,无法对隧道孔的大小、深度分布等进行控制。相比之下,激光照蚀则可得到孔的大小、深度均匀的铝箔。铝电解电容器激光打孔装置实现了自动化加工电解电容多孔铝箔,节约了大量的人力物力资源,使多孔铝箔向着更加高效化和智能化的方向前进。详细介绍了运用激光打孔装置制造阳极箔的优点以及激光打孔装置的整体、各部分构造和工作原理,结合国内外的同类课题研究情况,为后续的阳极箔生产提供依据。

Controlling limiting length of tunnels on Al foil electroetched in HCl-H_2SO_4 solution

The limiting length of tunnels, llim, of Al foil electro-etched in HCl-H2SO4 solution and the corresponding anodic polarization curves in the same solution were measured. It is found that there is a dependence of llim on the potential difference, △φ, between the pitting potential, φpit, and the corrosion potential, φcorr, of Al foil, when the temperature and H2SO4 concentration of HCl-H2SO4 electrolyte are changed. The dynamic equation on the tunnel growing and the linear equation between llim and △φ were deduced by analyzing the relationship among the over-potential on Al foil surface, the transport over-potential in tunnel solution and the over-potential at tunnel tip during the electro-etching. The results show that the growing velocity of tunnels decreases with their extending in length and the changing trend of llim can be judged by measuring △φ, which supplies a convenient access to explore new kinds of etchants.

高比表面积铝电解电容器用电极箔的研究进展

随着科学技术的飞速发展,电子产品正朝着更多功能和更小尺寸的方向演进。作为最为广泛使用的电子器件之一,铝电解电容器亦顺应这一趋势,迈向更小体积和更大容量的发展。为实现这一目标,制备具有高比表面积的电极箔成为关键途径之一。本文全面梳理了多种扩大铝箔比表面积的方法,详细阐述了包括化学腐蚀法、电化学腐蚀法和粉末烧结法在内的多种扩大铝箔比表面积技术,及其影响因素与优缺点。在总结现有技术的基础上,展望了铝电解电容器阳极箔比容量提升的未来发展趋势。

快车速制备铝电解电容器用阳极箔的腐蚀发孔动力学

研究了阳极铝箔在快车速腐蚀工艺体系下,采用异形电极变电流和多级腐蚀工艺条件下,隧道孔在各阶段的发孔密度、孔径、孔长的变化规律。结果表明:发孔行为主要集中在短时大电流密度的电化学腐蚀阶段,而电流衰减阶段的孔长生长最快。随腐蚀周期的增加,孔密度、孔长在第一至第二个周期中期迅速增长,在第二个周期中期至第五个周期结束期间变化平缓。快车速腐蚀工艺将发孔与孔长增长行为有效隔离,通过多级腐蚀既提高了腐蚀效率,又增强了比电容的可控性及发孔的均匀性。

微量Mg对高压电子铝箔腐蚀结构的影响

采用立方织构定量检测以及扫描电子显微镜下观察腐蚀结构等手段 ,对比了不同微量Mg元素含量的高压电解电容器阳极铝箔在织构和腐蚀结构上的差别 ,研究了Mg含量对高压电解电容器阳极铝箔比电容的影响。分析表明 :Mg含量从 0 .0 0 0 1%提高到 0 .0 0 14 %时 ,Mg会更多富集于铝箔表面 ,促使腐蚀形成的氧化膜中出现含Mg的复合氧化物微小颗粒 ,进而引起腐蚀隧道的侧向发展 ;频繁的侧向发展可导致表层腐蚀组织剥落 ,进而使铝箔在 5 0 0V的比电容从 7.3× 10 -3 F/m2 降低到 4 .3× 10 -3 F/m2 。

电解工艺条件对铝箔腐蚀形貌与比电容的影响

利用扫面电镜(SEM)、数字电桥研究了铝电解电容器用高压电子铝箔在硫酸+盐酸体系中进行电化学腐蚀扩面时,工艺条件对铝箔腐蚀形貌与比电容的影响规律:电解腐蚀时间对铝箔腐蚀后形貌与比电容影响较大,发孔时间延长、扩孔时间缩短,隧道孔密度增加、孔直径减小;发孔电流密度对铝箔腐蚀形貌与比电容影响较小,只要高于点蚀电流密度,小电流长时间发孔与大电流短时间发孔都可以在铝箔表面形成足够密度的蚀孔结构;电解液温度对铝箔腐蚀形貌和比电容影响较大,随着发孔液温度的提高,蚀孔密度增加、蚀孔孔径减小,隧道孔长度减小。

微观结构和微量元素对铝箔腐蚀结构的影响

观察了经300℃退火并分别快冷和慢冷的铝箔表面的电化学腐蚀结构。利用二次离子质谱仪检测了铝箔表面区域Fe、Si、Cu、Mg等微量元素的分布。结果显示:Mg在铝箔外表面的富集高于铝箔内部4个数量级,Fe、Si的富集程度约高2个数量级,而Cu则不足1个数量级。退火后慢速冷却会造成富集于表面的微量元素偏聚于晶界和位错周围,从而会加重腐蚀结构的不均匀性并降低铝箔的比电容。

晶界对低压电解电容器铝箔腐蚀结构的影响

采用扫描电子显微镜和背散射电子取向成像技术分析研究了低压电解电容器用阳极铝箔的腐蚀结构、晶粒尺寸和晶界分布对比电容的影响及相关机理。结果表明,在铝箔的晶界附近,尤其是大角度晶界附近容易出现尺寸较大的腐蚀孔坑或沟道,造成腐蚀结构的不均匀性并降低比电容。该晶界优先腐蚀的现象起因于晶界的高缺陷密度和与之相应的腐蚀电流密度的局部集中。增加晶界密度可以降低杂质原子偏聚程度和电流密度分布的不均匀性,因此在一些特定的电化学腐蚀条件下可以借助减小晶粒尺寸的方式提高比电容。

高压电子铝箔阳极电解扩孔行为

研究发孔铝箔在盐酸和硝酸溶液中的阳极极化行为与扩孔特性的关系。阳极扩孔的基本条件是将发孔箔的内、外表面都控制在钝化状态下。在盐酸溶液中,阳极极化时存在点蚀电位和一个较小的钝化电位区,当扩孔施加的电流密度大于临界点蚀电流密度时,铝箔表面发生二次发孔,导致形成孔蚀族与并孔,腐蚀箔厚度减薄,比电容显著降低。在硝酸溶液中,阳极极化时存在一个宽阔的钝化电位区,因此硝酸扩孔比盐酸扩孔容易控制,不会发生二次发孔。提高盐酸或硝酸浓度与温度均可以增大最大维钝电流密度,即增大扩孔的最大电流密度,提高扩孔的生产效率。

铝电解电容器铝箔的研究现状和技术发展

简述了电解电容器用铝箔(原箔)的国内外生产技术研究现状及发展趋势。分析了电容器铝箔的特性要求,原料的制造技术,近年来铝电解电容器用铝箔研究取得的最新成果,电容器铝箔的技术难点、存在问题、未来技术发展趋势。指出了国产铝电解电容器用铝箔与国外同类产品在生产技术上存在的差距,探讨了相应的解决方案及发展前景。

预处理对铝箔电蚀特性的影响

介绍各种预处理条件的功能及对铝箔电蚀性能和最终静电比容的影响。主要的预处理包括：表面清洗，热处理，表面氧化，阴极极化和金属元素的表面沉积等。预处理的作用是通过改善铝箔的结构，尤其是表面结构，提高其电蚀性能，达到充分扩大表面积的目的。大量的研究结果表明，预处理是提高腐蚀箔静电容量的有效措施之一。基于对文献的研究分析。

缓蚀剂对高压铝箔电蚀特征的影响

利用扫描电镜分析了盐酸+硫酸混合酸电解液中添加适量缓蚀剂聚乙二醇或聚丙烯酸对高压铝箔电解腐蚀后表面形貌与横截面形貌的影响,利用LCR仪与电子天平测试了铝箔比电容与质量失重率。结果表明:缓蚀剂可以改善电解腐蚀后铝箔表面隧道孔孔径的分布,使隧道孔由圆锥状转变为圆柱状,降低隧道孔的并孔团簇现象,这有利于提高铝箔电解腐蚀扩面后的实际表面积;同时铝箔的实际质量失重率明显降低,铝箔的比电容显著增加。