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.

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...

Reliability of DC-link capacitor in pulsed power supply for accelerator magnet

Capacitors are widely used in pulsed magnet power supplies to reduce ripple voltage,store energy,and decrease power variation.In this study,DC-link capacitors in pulsed power supplies were investigated.By deriving an analytical method for the capacitor current on the H-bridge topology side,the root-mean-square value of the capacitor current was calculated,which helps in selecting the DC-link capacitors.The proposed method solves this problem quickly and with high accuracy.The current reconstruction of the DC-link capacitor is proposed to avoid structural damage in the capacitor’s current measurement,and the capacitor’s hotspot temperature and temperature rise are calculated using the FFT transform.The test results showed that the error between the calculated and measured temperature increases was within 1.5℃.Finally,the lifetime of DC-link capacitors was predicted based on Monte Carlo analysis.The proposed method can evaluate the reliability of DC-link capacitors in a non-isolated switching pulsed power supply for accelerators and is also applicable to film capacitors.

DC-Link Capacitor Optimization in AC–DC Converter by Load Current Prediction

Alternating Current–Direct Current(AC–DC)converters require a high value bulk capacitor or afilter capacitor between the DC–DC conversion stages,which in turn causes many problems in the design of a AC–DC converter.The component package size for this capacitor is large due to its high voltage rating and capacitance value.In addition,the high charging current creates more pro-blems during the product compliance testing phase.The shelf life of these specific high value capacitors is less than that of Multilayer Ceramic Capacitors(MLCC),which limits its use for the highly reliable applications.This paper presents a fea-sibility study to overcome these two problems by adding a few sensing mechan-isms to the typical AC–DC converter topology.In majority of the AC–DC converter,Al-Elko capacitor takes approximately 3%to 5%of the converter size.The proposed method reduces this to approximately 50%size and so it effectively approximates 2%to 3%size reduction in converter size.The proposed method basically works based on the load current prediction method and hence it is highly suitable for the constant load application.Moreover,the converter response time increases in this method,which limit its application in high-speed systems.The high temperature application of Al-Elko capacitor is limited because of its poor performance,which is significantly rectified by replacing the Al-Elko with MLCC as it delivers good performance in high temperature.

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.

Growth and passivation of aluminum etch tunnels at on-off controlling direct current in 6 wt.% HCI solution

Growth and passivation of tunnels within Al foil by on-off controlling DC etching in 6 wt.% HCI solution has been investigated. It was found that, in a given etchant solution at a special temperature, the longest tunnel length was only a function of the turn-on interval of DC. The potential of Al foil broke at on-off controlling DC by the result from anode polarization curves and potential-time （E-t） responding curves. When DC was switched on, the potential increased abruptly over pitting potential, leading to nucleation of pits at the surface and the growth of tunnels at special length. When DC was switched off, the potential decreased rapidly to a passive value, leading to stoppage of nucleation and death of tunnels. By this way, the longest tunnel length can be controlled and a non-piercing layer can be obtained. Hence, etching of Al foil at this current is beneficial for maintaining a good mechanical strength.

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.

Morphological evolution of tunnel tips for aluminum foils during DC etching

The morphologies of tunnel tips in different stages for aluminum foils during DC etching in 1.5 mol/L HC1 solution at 90℃ were observed by field emission scanning electron microscopy （FE-SEM）. A novel model was proposed to describe the morphological evolution of tunnel tips throughout the growth processes. In the pit nucleation stage, the pits vary from the hemispherical to half-cubic shapes due to the activation of pit tips from the center to the edge. During the tunnel growth stage, the pits dissolve toward the depth direction and develop into the tunnels, and their tips remain flat. In the tip passivation stage, as the passivation of tunnel tips speeds up from the edge to the center＇s the tunnel tips change from flat shapes to three-dimensional protrusions. The mechanism may be attributed to the order of activation or passivation on the tunnel tips changed in different stages.

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.

冲击载荷下液态铝电解电容失效规律研究

目的为了探究电子雷管内部电容在冲击载荷作用下的失效规律。方法以电子雷管中常用的液态铝电解电容为例,利用水下爆炸的方法对液态铝电解电容进行冲击实验。研究不同强度冲击载荷作用下液态铝电解电容的电压变化特性,通过电流变化曲线确定电容的失效过程,通过解剖失效样品对失效原因进行分析。结果结果表明,液态铝电解电容在受到冲击载荷作用后,电压会瞬间下降,随后再缓慢上升,失效模式为短路失效;在13.6MPa~35.7MPa的超压作用下,电容均出现此类现象,且随着冲击强度增大,电压下降幅度增大,电压恢复所需要的时间变长;电容发生短路失效的原因主要包括溢出的电解液与阳极引线接触、阳极铝箔表层氧化膜在应力作用下发生撕裂。结论液态铝电解电容受冲击后易短路失效,具体失效规律可为抗振型电子雷管的设计提供参考。

基于性能退化的铝电解电容寿命预测方法研究

应用表明铝电解电容是电源系统中故障率最高的元件,是影响电源系统长期运行可靠性的关键器件。为了评估铝电解电容在长期应用条件下的可靠性与寿命,对铝电解电容退化机理与退化模型进行研究分析,在已有模型研究成果的基础上,结合铝电解电容加速退化试验数据,提出了一种基于幂函数的电容量退化轨迹模型。采用该退化轨迹模型,开展了基于退化量分布的铝电解电容退化数据统计分析与寿命预测。根据寿命预测结果,某型铝电解电容在正常工作条件下95%可靠寿命超过18年。

超低温铝电解电容器电解液的制备及其应用

以制备工作下限温度为-55℃的超低温铝电解电容器电解液为研究目的,通过对二元混合溶剂的凝固点的分析以及对溶质和添加剂的选用,将各种物质进行正交实验、优化配制技术。制备出的电解液的冰点低于-55℃,闪火电压(Us)≥496 V。将该电解液应用于规格为400 V,10μF的铝电解电容器,对电容器进行低温特性、高温负荷和高温耐久试验。结果表明,该电解液制备的电容器可在-55~105℃的环境下工作至少5 000 h。

不同温度下形成的阳极氧化铝膜介电性能的研究

为了改善铝电解电容器漏电流较大的问题,从阳极氧化温度的角度出发,对比了在常温20℃以及高温80℃通过阳极氧化形成的阳极氧化膜的闪火电压,并测试其漏电流以及表面形貌。结果表明,所用六种电解液的闪火电压都在490~535 V之间,在高温下阳极氧化膜的漏电流比常温下的低30%~62%。从扫描电子显微镜的结果中得到高温下形成的阳极氧化膜断面上的孔洞比常温下的更少,孔径更小,从而导致高温下的漏电流更低。该结果对电容器工作电解液的研发和电容器生产过程中老练工艺的改进有重要的指导意义。

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。

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。

耐低温液态铝电解电容器开发方法的研究

电子元器件宽温化是必然趋势,为保障铝电解电容器低温性能的可控性,通过对电容器等效电路模型的梳理,建立了电容器低温容量比α_(xx)和工作电解液的低温电导率σ_(xx)之间的关系式,并进行了实验验证。研究结果表明:当电容器材料配套与工作电解液相匹配时,经关系式估算和实验验证发现,低温下电容器要求满足一定容量比所需的实际电导率σ_(测)与估算电导率σ_(算)误差约5%,说明α_(xx)和σ_(xx)的关系式具有较高的参考价值。根据结果得出开发耐低温电容器的方法:先选定材料配套和相匹配的工作电解液制成电容器,测试和计算相应的参数;然后由低温下电容器需要的容量比α_(xx)根据关系式估算出需要的电导率σ_(算),再通过对电解液低温电导率的改善,调试出新电解液,然后按原材料配套和新电解液可制成满足低温要求的电容器。

麻竹纤维制备铝电解电容器隔膜性能研究

本研究在低紧度下,以麻竹浆和剑麻浆为原料,经相同的过程处理后,通过PFI磨浆处理,采用PTI湿法成形制备单层铝电解电容器隔膜,探讨麻竹浆作为电解电容器隔膜原料的可行性。对浆料制备的电解电容器隔膜孔径结构、吸水性能、绝缘性能进行测试。结果表明,打浆度20、65°SR的麻竹隔膜平均孔径分别为24.88、1.11μm,Cobb吸水值分别为26.89、35.59 g/m^(2),交流击穿强度分别为59.12、97.98 kV/cm。打浆度20和65°SR的剑麻隔膜平均孔径分别为26.67、7.12μm,Cobb吸水值分别为21.25、33.24 g/m^(2),交流击穿强度分别为50.68、92.21 kV/cm。麻竹隔膜的表面吸水能力、击穿强度大于剑麻隔膜,同时其孔径小于剑麻隔膜,说明麻竹浆可以做铝电解电容器隔膜原料。

中高压铝电解电容器工作电解液的制备研究

以乙二醇为主溶剂,癸二酸铵为主溶质,研究辅助溶质和添加剂对中高压铝电解电容器用工作电解液性能的影响。结果表明,当甘露醇、五硼酸铵分别为2.0%和3.0%,并添加0.8%的高分子聚合物时,制备的电解液40℃时的p H为5.96,电导率为2 050μS·cm^(-1),初闪电压为417 V,500 V以上闪火时间为73 s,制作的电容器(400 V-6.8μF)漏电流为12.5μA,损耗为0.052。

老练温度对中高压铝电解电容器性能的影响

本文选择了市面上常见的3种中高压铝电解电容器,并在90~110℃中选取5个温度进行手工高温老练试验。通过对电容量、损耗角正切和漏电流3个性能参数的分析,评估了电容器性能的稳定性和老练效果。研究结果表明,在90℃和105℃的高温老练条件下,电容器的性能有显著提升。特别是在105℃的高温老练条件下,CD11GS型250 V电容器和CD11MA型400 V电容器经过高温老练后展现出最佳性能。而对于CD11GS型450 V电容器来说,在90℃的高温老练条件下表现出最佳性能。这些研究结果表明,高温老练温度对中高压铝电解电容器的性能有显著影响。这些发现对于改善电容器的性能稳定性和优化老练工艺具有重要意义。此外,这些研究还为有关中高压铝电解电容器的老练工艺提供了实验基础和性能参数分析方法。