Three-dimensional modeling of effect of surface intermetallic phase on surface defects of Al-Fe-Si aluminum foils during twin-roll casting

Scanning electron microscopy and X-ray energy dispersive spectrum analysis show that the clusters of intermetallic AlFeSi particle are distributed on or near the aluminum foil stock surfaces heterogeneously. 3D finite element modeling shows that these clusters of hard particles induce the fracture of the nano-scale lubricant oil film at first and further lead to severe deformation in the nearby aluminum foil substrate along the rolling direction. Consequently, the optical property in this region differs from that in the surroundings, resulting in surface defects.

Multilayer aluminum composites prepared by rolling of pure and anodized aluminum foils

Experimental results on processing,structural and mechanical characterization of a multilayer composite based on commercially pure aluminum foils were presented.A multilayer composite was produced by hot-rolling of anodized and non-anodized aluminum foils alternately sandwiched.In addition,the same process was applied for bonding of non-anodized foils.In both cases,obtained multilayer composites were compact and sound.In order to study composites microstructural evolution and mechanical properties,optical and scanning electron microscopy(SEM),energy dispersive spectrometry(EDS),X-ray diffraction(XRD)analysis,hardness,tensile and three-point flexural tests were performed.Microstructural characterization confirmed that the rod-like particles distributed in parallel rows in the composite aluminum matrix with anodized foils correspond to Al2O3.Maximum and minimum peaks of oxygen and aluminum,respectively,suggest that after the final hot-rolling of composite with non-anodized foils,a small amount of coarser particles were formed at boundaries between foils.Hardness,strength,modulus of elasticity and flexural strength of both multilayer composites were much higher than those of pure aluminum,whereas ductility was significantly less.The composite with anodized foils exhibited the highest strength and modulus of elasticity,but lower ductility compared to composite processed from non-anodized foils.Fracture failure corresponded to the change of ductility.

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 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.

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...

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.

Icephobic performance on the aluminum foil-based micro-/nanostructured surface

The research of superhydrophobic materials has attracted many researchers＇ attention due to its application value and prospects.In order to expand the serviceable range,people have investigated various superhydrophobic materials.The simple and easy preparation method has become the focus for superhydrophobic materials.In this paper,we present a program for preparing a rough surface on an aluminum foil,which possesses excellent hydrophobic properties after the treatment with low surface energy materials at high vacuum.The resulting contact angle is larger than 160° and the droplet cannot freeze on the surface above-10 ℃.Meanwhile,the modified aluminum foil with the thickness of less than 100 μm can be used as an ideal flexible applied material for superhydrophobicity/anti-icing.

Effects of HNO_3 concentration on the pit morphologies of aluminum foil etched in HNO_3–HCl and HNO_3–H_2SO_4–HCl solutions

In this work, the effects of HNO3 concentration on the pit morphologies of high-cubic-texture aluminum foil etched in HNO3-HCl and HNO3-H2SO4-HCl solutions were investigated. When the aluminum foil was etched in HNO3-HCl solutions, the morphologies of pits transformed from irregular tunnels to typical tunnels （as inverted pyramids） and shallow cuboids as the HNO3 concentration in the etchant solution was increased. However, as the HCl concentration in the etchant solution was increased, the morphologies of pits transformed from shallow cuboids to typical tunnels （as inverted pyramids） and irregular tunnels. When the aluminum foil was etched in n N HNO3-（7.2-n） N H2SO4-0.8 N HCl solutions, the morphologies of the pits transformed from typical tunnels （i.e., the number of sub-tunnels formed on the main tunnels increased） to irregular tunnels （corrugated tnnnels and polyline tunnels） as the HNO3 concentration in the etchant solution was increased. These effects are attributed primarily to corrosion on the （100） and （010） faces of pits being accelerated and to the （001） faces be- ing prone to passivation to different degrees when various concentrations of HNO3 are added to the etchant solutions.

ANALYSIS OF ROLL SYSTEM STABILITY ABOUT ALUMINUM FOIL MILLS

To improve roll system stability of aluminum foil mills, roll system stability of 2200 highspeed aluminum foil mill is analyzed with energy stable method. Two different restrictive conditions which gaps between chock of work roll and window of stand whether exist or not, are studied respectively. A new concept of roll system with open /closed compound pair conies up with as well for re-newably synthesizing restrictive mechanism of aluminum foil mills' chock. Through these studies, the conflict, whether reserving the gap for the roller replacement or eliminating the gap for roller's normal work, is successfully settled. This concept and analyzed result give the actual mechanism with open/closed compound restriction and the method of realizing high-speed rolling and prolonging longevity of end thrust bearing on work roll. It has important theoretical meaning and engineering value for modern technical reform of aluminum foil mills and plate strip mills.

Contribution to the understanding of the performance differences between commercial current collectors in Li–S batteries

Lithium–sulfur batteries have been recognised as highly promising next-generation batteries, due to their low cost and high theoretical energy density. Despite numerous advances in this technology over the last decade, its commercialisation is still a challenge that has not yet been achieved. Many efforts have been made to improve the problems that these batteries present, mainly by investigating different cathode manufacturing strategies, testing novel Li anodes, new additives in the electrolytes, and modified separators or interlayers. However, the characteristics of the current collectors used in the preparation of the electrodes have been rarely addressed. Three commercial collectors are commonly used in basic research on Li–S batteries: Al foil, carbon coated Al foil (Al-C), and carbon paper (gas diffusion layer, GDL). In this work, a detailed study of the electrochemical response of these commercial collectors has been carried out. The tests were carried out on two S composites formed by carbons of a different natures, commercial carbon black and synthetic N-doped graphene. In addition, the S impregnation method was different, using either melt diffusion at 155 ℃ or ethylenediamine as S solvent, respectively. In both systems, the results were similar – the electrodes supported on GDL delivered higher specific capacities than those supported on Al and Al-C, with minimal differences between the two. Of the different collector properties examined to explain this behaviour, namely Al corrosion, electrical conductivities, surface-level composition, and surface texture, only the latter had a significant effect in the performance of GDL-based electrodes. SEM images revealed a rough and cracked surface formed by the agglomerated carbon particles that give rise to a complex pore system, predominantly consisting of macropores. All of these features are beneficial for a better anchoring of the active material on the collector surface, in addition to enhancing the wettability of the electrolyte and favouring reaction kinetics. In contrast, the Al-based collector possesses a very smooth and non-porous surface, detrimental to both the active material-substrate interface and the active material impregnation by the electrolyte.

Hybrid and Reflective Insulation Assemblies for Buildings

Materials with a low thermal emittance surface have been used for many years to create reflective insulations that reduce the rate of heat flow across building envelopes. Reflective insulation technology is now being combined with other energy conserving technologies to optimize overall thermal performance. The basis for the performance of reflective insulations and radiant barriers will be discussed along with the combination of these materials with cellular plastic or mineral fiber insulations to form hybrid insulation assemblies. Calculations of thermal resistance for enclosed reflective air spaces and current field data from Southeast Asia will be presented. These data show that reductions in heat transfer across the building enclosure can be effectively reduced by the use of enclosed reflective air spaces and attic radiant barriers. Reflective technology increases the overall thermal resistance of the building enclosure when used to insulate poured concrete structures.

Formation of Al-Si Composite Oxide Film by Hydrolysis Precipitation and Anodizing

This paper presents a new technique in the high dielectric constant composite oxide film preparation. On the basis of nano-compsite high dielectric constant aluminum oxide fdm growth technology, a new idea of adulterating Si oxide species into the aluminum composite film was proposed. As a result, the specific capacitance and withstanding voltage of the composite oxide film formed at the anodizing voltage of 20V are enhanced, and the leakage current of the aluminum composite oxide fdm is reduced through incorporation of Si oxide species.