铝电解电容器用高介电常数复合氧化膜的制备

用水解沉积-阳极氧化法制备高介电常数的Al-Ti复合氧化膜,通过XPS分析Al-Ti复合氧化膜的成分及各元素的相对含量.监测铝电极箔恒电流阳极氧化过程中的升压曲线,对复合氧化膜的介电常数进行理论计算,并测试铝电解电容器的容量及耐久性.结果表明:铝电极箔在含钛无机盐溶液中的最佳处理时间为10min,处理后的铝电极箔阳极氧化速率高于纯铝电极箔,Al-Ti复合氧化膜中的高介电常数相为TiO2.对16V/1000μF规格的铝电解电容器,形成Al-Ti复合氧化膜的样品,容量提高率为23%,且耐久性良好,复合氧化膜介电常数的理论计算值与实验结果较为一致.     

水解沉积--阳极氧化法形成Al-Ti复合氧化膜

通过含钛无机盐的水解沉积及高温热处理,铝电极箔表面形成高介电常数氧化物———TiO2 膜层,然后在己二酸铵溶液中恒电流阳极氧化,形成 Al Ti复合氧化膜。AFM观测了含钛无机盐水解沉积过程中,铝电极箔表面形貌的变化。在铬酸和磷酸的混合溶液中测试了氧化膜的耐电压随溶解时间的变化。通过SIMS检测了复合氧化膜中 Al3 、Ti4 的强度随溅射时间的变化。膜溶解试验及 SIMS 检测结果表明Al Ti复合氧化膜由 3 层组成,外层和中间层为 Al、Ti、O不同配比的混合物,内层则为纯的 Al2O3。铝电极箔比容随氧化膜耐电压的变化关系曲线表明,60V耐电压下,Al Ti复合氧化膜的比容提高率为51%。     

高压铝阳极箔制备技术研究进展

从高压铝阳极箔的立方织构、腐蚀技术、化成工艺等方面概述了目前高压铝电解电容器用电极箔研究领域的最新进展,其中包括加入稀土净化铝锭基体、发坑和扩孔的腐蚀技术、复合高介电常数氧化膜.最后预测了超高压、电真空沉积氧化膜的发展方向.     

剧烈-温和阳极氧化结合法快速制备有序阳极氧化铝膜的研究

本研究采用剧烈-温和阳极氧化(hard anodization-mild anodization, HA-MA)结合快速制备高度有序多孔阳极氧化铝(porous anodic alumina, PAA)膜的方法, 即先利用HA在铝表面快速形成有序凹坑阵列, 然后再对表面留有有序凹坑的铝基进行温和阳极氧化, 制备出有序PAA膜。研究了剧烈阳极氧化时氧化电压、氧化时间对所制备PAA膜有序度的影响。研究结果表明, HA-MA结合法制备PAA膜的优化HA参数为: 0.3 mol/L硫酸、80 V、10 min。HA-MA结合法所制备PAA膜的有序性和机械稳定性与二步温和阳极氧化法的相近, 但形成有序PAA膜所需的时间为4.5 h, 约为温和阳极氧化法的1/4, 极大地提高了高度有序PAA膜的制备效率。     

多孔阳极氧化铝形成机理的研究综述

铝阳极氧化已经研究了五十多年,涉及铝阳极氧化膜的实验数据十分丰富,然而阳极氧化过程的本质特别是多孔氧化膜的生长机制迄今为止还远未认识清楚。近些年,随着纳米技术的兴起,多孔氧化铝膜作为理想的纳米结构模板材料倍受国内外学者的关注,对多孔氧化铝膜形成机理的研究显得尤为重要。本文对多孔阳极氧化铝的结构、形成机制方面的历史发展和现状进行了综述。指出了大多数学者认同的“酸性场致溶解”理论的缺陷。作者认为铝多孔氧化膜形成机理的研究具有重大的理论意义和实际应用价值,同时也会促进其他多孔阳极氧化物形成机理的认识。     

铝箔阳极氧化后2种铈转化膜的沉积机理

为探讨铝阳极氧化沉积铈转化膜形成机理,分别用化学沉积和电沉积法在铝阳极氧化膜上制备了铈转化膜._用SEM和EDS表征了阳极氧化膜、化学沉积铈转化膜和阴极电沉积铈转化膜的形貌和组分,测试了膜层厚度和膜的耐腐蚀性.结果表明:平均孔径89 nm的铝阳极氧化膜经阴极电沉积、化学沉积铈后平均孔径分别减小为38 nm和32nm,2种沉积分别可得到含铈52.10%和20.39%的铈转化膜.2种铈转化膜的平均膜厚分别比铝阳极氧化膜的大1.96 μm和1.23 μm,极化电阻均是铝阳极氧化膜的近3倍.2种铈转化膜形成机理不同是造成它们性质不同的原因.     

铝阳极氧化机理研究的进展

综述了铝阳极氧化膜的结构、形态与介质的关系有孔洞形成的原因。     

包铝层和氧化时间对2E12铝合金硫酸阳极氧化及膜层性能的影响

对保留表面包铝和去除包铝的2E12-T3铝合金采用硫酸阳极氧化处理工艺,研究了包铝层和氧化时间对铝合金阳极氧化行为及膜层耐蚀性的影响。采用扫描电子显微镜观察氧化膜的表面以及截面形貌,应用动电位扫描极化曲线和电化学阻抗谱对膜层的电化学性能进行分析。结果表明:两种铝合金表面均能形成具有防护性能的阳极氧化膜,膜层随氧化时间延长而增厚。富铜的第二相颗粒会使得不带包铝的2E12铝合金氧化膜具有更多孔洞缺陷,甚至出现微裂纹。保留包铝的2E12铝合金表面氧化膜更厚,孔洞缺陷少,耐蚀性更好。阳极氧化30min和45min的2E12铝合金阳极氧化膜具有较低的腐蚀电流和较高的多孔层阻抗,耐蚀性好。     

染色和封孔对铝阳极氧化膜结构和耐蚀性的影响

目前,染色和封孔对铝阳极氧化膜的结构和耐蚀性的影响尚不清楚,且有机染色工艺还不够好。采用200 g/L H2SO4电解液在高纯铝表面制备了综合性能良好的阳极氧化膜,通过含芳香烃的有机偶氮染色剂DLM2203和DLM2707对铝阳极氧化膜进行染色处理,用沸水对染色膜进行封孔处理。采用扫描电镜(SEM)、X射线衍射仪(XRD)、红外光谱仪等分析铝阳极氧化膜及染色膜的表面形貌和相组成,并采用动电位极化曲线、电化学阻抗谱等分析铝阳极氧化膜和染色膜的耐蚀性能。结果表明:铝阳极氧化膜染色均匀,表面平整;染色膜经过沸水封闭处理后,其外观颜色变浅;铝阳极氧化膜经染色处理后,厚度和显微硬度都略有增大;沸水封闭导致染色膜厚度略有增大,而显微硬度减小;铝阳极氧化膜的部分孔洞可被DLM2203染色剂充分吸附而成功染色;DLM2707有机染色剂对铝阳极氧化膜有一定的腐蚀作用;铝阳极氧化膜和2种染色膜的相组成相同;偶氮染料分子可以吸附在铝阳极氧化膜的多孔结构内与表面上;染色膜的腐蚀电流密度相对于高纯铝降低了4个数量级,耐蚀性能较好;铝阳极氧化膜与染色膜的阻抗值均处在同一数量级上,耐腐蚀性能基本相近。     

纳米多孔铝阳极氧化膜的形成机理研究

为探讨多孔铝阳极氧化膜的形成机理,研究了不同气压条件下铝在磷酸溶液中的阳极氧化过程,发现在真空下进行阳极氧化,氧气析出非常明显。通过测定不同气压下的阳极氧化曲线,分析了致密膜向多孔氧化铝膜的转化和生长过程,结果显示氧气析出是导致氧化膜从致密膜向多孔膜转变的主要原因。提出了在氧化膜/电解液界面上氧气分子的聚集是造成表面条纹的新观点。通过氧化膜断面的SEM形貌表征,首次发现多孔膜的主孔道中存在分孔道。分孔道的产生说明析氧反应不但在致密膜/电解液界面发生,而且在多孔膜孔壁/电解液界面也同时发生。     

Properties of aluminum oxide thin films deposited by pulsed laser deposition and plasma enhanced chemical vapor deposition

The chemical, structural, mechanical and optical properties of thin aluminum oxide films deposited at room temperature (RT) and 800 °C on (100) Si and Si-SiO₂ substrates by pulsed laser deposition and plasma enhanced chemical vapor deposition are investigated and compared. All films are smooth and near stoichiometric aluminum oxide. RT films are amorphous, whereas γ type nano-crystallized structures are pointed out for films deposited at 800 °C. A dielectric constant of ∼ 9 is obtained for films deposited at room temperature and 11-13 for films deposited at 800 °C. Young modulus and hardness are in the range 116-254 GPa and 6.4-28.8 GPa respectively. In both cases, the results show that the deposited films have very interesting properties opening applications in mechanical, dielectric and optical fields.     

Enhanced Dielectric Performance in Polymer Composite Films with Carbon Nanotube‐Reduced Graphene Oxide Hybrid Filler

The electrical conductivity and the specific surface area of conductive fillers in conductor‐insulator composite films can drastically improve the dielectric performance of those films through changing their polarization density by interfacial polarization. We have made a polymer composite film with a hybrid conductive filler material made of carbon nanotubes grown onto reduced graphene oxide platelets (rG‐O/CNT). We report the effect of the rG‐O/CNT hybrid filler on the dielectric performance of the composite film. The composite film had a dielectric constant of 32 with a dielectric loss of 0.051 at 0.062 wt% rG‐O/CNT filler and 100 Hz, while the neat polymer film gave a dielectric constant of 15 with a dielectric loss of 0.036. This is attributed to the increased electrical conductivity and specific surface area of the rG‐O/CNT hybrid filler, which results in an increase in interfacial polarization density between the hybrid filler and the polymer.     

聚偏氟乙烯基复合材料的制备及介电性能

为有效改善聚合物基复合材料的介电性能,兼顾高介电常数和低填料量同时并存,采用以聚偏氟乙烯(PVDF)为基体树脂,钛酸钡(BT)和石墨烯(GNP)分别为介电填料和导电填料,在BT-GNP/PVDF复合体系内部构建微电容器结构.采用溶液法和热压法制备GNP/PVDF薄膜和BT-GNP/PVDF复合薄膜.结果表明,BT和GN...     

改性石墨烯/聚(偏二氟乙烯-共-六氟丙烯)复合材料薄膜的制备与性能

采用改进Hummers法对天然鳞片石墨进行氧化和超声剥离处理制备氧化石墨烯（GO）,将十三氟辛基三乙氧基硅烷（FAS）与GO反应并还原得到FAS修饰的还原氧化石墨烯（FAS-RGO）。利用溶液涂覆成膜工艺制得FAS-RGO/聚（偏二氟乙烯-共-六氟丙烯）（P（VDF-HFP））复合材料。采用FTIR、XPS、XRD、Raman和TEM表征了FAS-RGO的结构与形貌,同时研究了FAS-RGO用量对FAS-RGO/P（VDF-HFP）介电性能的影响。结果表明：FAS包覆在RGO的表面,有效解决了RGO容易团聚的问题,并且FAS的引入提高了RGO与P（VDF-HFP）的界面结合,改善了RGO在P（VDF-HFP）中的分散性,FAS-RGO还能提高P（VDF-HFP）的结晶性,促进形成β晶型。当FAS-RGO的体积分数为1.6vol%、在100 Hz频率时,FAS-RGO/P（VDF-HFP）复合材料的介电常数为62,较纯P（VDF-HFP）提高了5.2倍,同时FAS-RGO/P（VDF-HFP）复合材料的介电损耗较低。     

具有多层结构的聚合物复合薄膜的介电和磁性能

采用旋涂法制备了 Fe3 O4/聚偏氟乙烯(PVDF)复合薄膜(A)、多壁碳纳米管(MWCNT)/PVDF复合薄膜(B)以及纯PVDF薄膜(P)。利用热压法制备具有3层结构的AAA、ABA及APA 复合薄膜。为了探究层状结构对复合薄膜介电和磁性能的影响,制备了单层膜A作为对比(厚度与AAA复合薄膜相同)。分别研究了薄膜的介电和磁性能。结果表明：由于界面效应,同等厚度的AAA复合薄膜较A膜而言具有较高的介电常数;以B和P薄膜替代AAA结构中间层薄膜后,其中ABA复合薄膜的介电常数高于AAA及APA复合薄膜,同时保持较低的介电损耗。对于磁性能,层状结构对复合薄膜的饱和磁化强度及矫顽力均无明显的影响,而ABA复合薄膜的饱和磁化强度高于AAA及APA复合薄膜,且ABA和APA复合薄膜的矫顽力增加。层状结构设计不仅能够调节复合材料的介电性能和磁性能,而且有利于不同纳米填料的分散,为制备多功能聚合物复合材料提供了一定的借鉴作用。     

Improvement electrical properties of sol–gel derived lead zirconate titanate thick films for ultrasonic transducer application

In this work, a fabrication process of piezoelectric PZT [Pb(Zr_0.52Ti_0.48)O₃] thick films up to 60 μm deposited on silicon and aluminum substrates is reported. Crystalline spherical modified PZT powder about 300 nm in diameter was used as filler. PZT polymeric precursor produced by Chemat Inc. was used as the matrix material. Spinning films were annealed at 700 °C for one hour in the furnace in air. The thickness of the thick films was measured using a scanning electron microscope (SEM). Compared with previous piezoelectric PZT composite films, the modified piezoelectric thick films exhibit better dielectric properties. The dielectric constant is over 780 and dielectric loss is 0.04 at 1 KHz. Using a PiezoCAD model, the high frequency transducer was designed and fabricated. It showed a bandwidth of 75% at 40 MHz.     

Dielectric and thermal properties of novel three-component CCTO/MWCNTs/polyarylene ether nitrile composite films

In this paper, a series of calcium copper titanate/multi-walled carbon nanotubes (MWCNTs)/polyarylene ether nitriles composite films were obtained by ultrasonic shocking under the condition of constant temperature water bath (80 °C). The composite films were characterized by scanning electron microscope, differential scanning calorimetry (DSC), thermogravimetric analysis. It is confirmed that the MWCNTs were combined with the matrix well and the composite films possess excellent thermal stability. The glass transition temperatures of the composite films obtained from DSC curves were in a range of 224–230 °C. The initial decomposition temperatures and the maximum decomposition rate temperatures were all above 480 °C. Besides, the dielectric and mechanical characterizations showed that the composite films possess excellent dielectric properties and flexibility. When the content of MWCNTs reached 6 wt%, the dielectric constant of the composite film increased to 35 (1 kHz), yet the dielectric loss is just 0.38 (1 kHz). Moreover, the composite films cannot break even though they were cured into columns of several layers, indicating the outstanding flexibility.     

Optical and dielectric properties of poly(vinylacetate)/lead oxide composites

Composite films of poly(vinylacetate)/red lead oxide have been prepared by mixing the fine lead oxide particles into polyvinylacetate solution under ultrasonication followed by film casting technique. Structural, optical and dielectric properties have been performed to characterize these composites films and compared their properties to pure PVAc film. The changes in the structural of the prepared films were investigated by X-ray diffraction (XRD) and FT-IR spectra. It has been observed that the crystallinity of the composites films depends on the Pb-content. Optical spectra of the composites films showed direct allowed band gaps lying in the range of 5.0–4.6?eV which is lower than that of PVAc. Frequency and doping level dependence of dielectric constant (ε′), ac conductivity (σ_ac) and tangent loss (tanδ) have been measured. The values of ε′ were decreased with increasing in frequency, which indicates that the major contribution to the polarization comes from orientation polarization. The ac conductivity is more for doped PVAc than that of undoped PVAc. The experimental results show that ε′ and σ_ac increase with adding of lead oxide in PVAc. The controllable of optical and dielectric properties of the composite film will draw much attention for potential applications.     

Dielectric properties of films prepared by the reactive sputtering of Ta In mixtures

The dielectric properties of amorphous films prepared by reactively sputtering tantalum in oxygen-nitrogen mixtures have been measured. As the nitrogen content in the sputtering discharge was increased, the dielectric constant decreased from 26 to 16 and the films became more suitable for capacitor fabrication (i.e. had lower leakage currents and higher breakdown voltages). Comparison with reported results for anodic films indicates that the nitrogen concentration in the films reached approximately 7 at.% at the lowest dielectric constant. Sputtered tantalum films were found to be suitable for base electrodes, whereas aluminum electrodes significantly increased the capacitor leakage currents.