High-purity Aluminum Foils Research Articles

エッチング開始直後のエッチピットの成長挙動

The capacity of the etched aluminum foil used in electrolytic condensers is determined by its surface area A study was conducted on the initiation and growth of pits in high-purity aluminum foils during DC etching in hot hydrochloric acid, and pit structures after etching were observed by SEM images of resin replicas(1) The electrode potential during DC etching moved from a period of high potential to one of stability with a transition period of up to 50ms. Pits were initiated during the high-potential period, and pits with facets grew during the stability period(2) The high-potential and stability periods were reproduced by potentiostatic electrolysis, and the structures of the pits were examined It was found that pits were initiated at an electrode potential of about -400mV vs S.C.E, and pits with facets grew at an electrode potential of about -670mV vs. S C E An attempt was also made to represent the direction of pit growth using fractal dimensions

Growth of bubbles during annealing of 600 MeV proton irradiated aluminium

Abstract High purity aluminium foils were irradiated with 600 MeV protons in the cyclotron of the Swiss Institute of Nuclear Research (SIN). In this type of irradiation, helium is produced by nuclear reactions simultaneously with displacement damage. The samples were studied by transmission electron microscopy (TEM) as irradiated and after successive isothermal anneals in vacuum. The bubble structure is found to be very stable, no growth being observed for annealing temperatures below 770 K (0.82 m , where T m is the absolute melting temperature). In the present study, the annealings were performed at 900 K in a sample irradiated to 2.8 dpa at 450 K. Overall statistics were used to study the resulting bubble distributions, bubble diameters varying between 2.5 and 10 nm. Distributions obtained after annealing samples thinned for TEM observations are compared to those observed after annealing 75 μ m thick irradiated samples, showing that the loss of information in the thinned sample is limited. Under these conditions it is discussed that the most probable growth mechanism is that of bubble coalescence, but it is not clear yet which is the operating diffusion mechanism.

電解コンデンサ用高純度アルミニウムはく

電解コンデンサ用高純度アルミニウムはく

Pitting Mechanism of Aluminum in Hydrochloric Acid under Alternating Current

The etching of high purity aluminum foils in hydrochloric acid under alternating current was investigated. Pit development and characteristics of etched foils were studied taking into account the a‐c amplitude, the frequency, the etching time, and the electrolyte temperature, using light micrography and scanning electron micrography. A maximum of electrical capacitance of etched and anodized foils is observed for certain frequency value ; and depend on the experimental conditions. The aluminum oxide formed on the metal etched surface exhibits minimum thickness for bath temperature near 60°C. Galvanodynamic voltammetry allows the determination of a pitting current and an induction time which depends on frequency. The pit density and the calculated anodic current efficiency for metal dissolution are found to decrease markedly with increasing frequency.

Sputtering of two alloy systems by polyatomic ions: AgAu and CuZn

High-purity, polycrystalline targets of Ag, Au, Cu and Zn, and alloys of AgAu and CuZn, were sputtered with monomer and trimer ions of arsenic at an energy of 45 keV per atom. Sputtered material was collected on high-purity aluminum foils during the approach to steady of the implant (low dose) and beyond (high dose). From an analysis of these collectors with Rutherford backscattering spectroscopy (RBS) the sputtering yields and angular distributions of atoms sputtered were measured. Analysis of the optical photon emission from the sputtered neutral atoms allowed a determination of the steady state fluence and surface fractions for some of the targets. The measured sputtering yields of Ag and Au agreed with measurements made by Thompson and Johar, demonstrating non-linear sputtering under polyatomic ion bombardment. Similar measurements were made with the Cu and Zn targets. The collectors exposed to alloy sputtering were studied for evidence of preferential sputtering enhancement above and beyond linear (mass-related) effects, which might be attributed to an onset of thermal processes as the density of a collision cascade is increased. The alloy targets were also analyzed for evidence of surface segregation and changes in bulk composition beneath the implanted layer.

Modulated Structures in Ion Implanted Al-Fe System

ABSTRACTThe results of transmission electron microscopy studies of iron implantation into high purity aluminum foils are described. For both 50 and 100 + 50 keV incident ion energies, modulated structure has been detected in the as-implanted foils. Upon annealing at 793 K the modulated structure decomposes into the Al matrix and Al3Fe precipitates for the 50 keV implantation. A similar annealing treatment for the 100 + 50 keV implantation indicates that the modulated structure is more stable, although some Fe3Al precipitation occurs.

Effects of hydrogen and inclusions on blistering in highpurity aluminium sheet and foil on a laboratory scale

A series of ingots was produced containing varying quantities of hydrogen and non-metallic (oxide) inclusions from melts of super purity aluminium. The incidence of blistering in sheet and foil was evaluated in terms of hydrogen content, melt cleanliness, thermomechanical treatment, and lubrication during rolling. Tensile properties were used to monitor the quality of the material. The importance of low hydrogen and inclusion contents and of maintaining a good surface quality during processing and the necessity for lubricant removal before annealing have been established as crucialfactors in the avoidance of blistering.

Conduction electron spin resonance in aluminium at 20.98 and 9.27 GHz

AbstractThe linewidths of the conduction electron spin resonances from high purity aluminium foils and films are measured at frequencies of 9.27 and 20.98 GHz using reflection spectrometers. An attempt is made to fit a breakdown of motional narrowing model to the data. It is found that such a model cannot satisfactorily explain the dependence of the linewidths on frequency, temperature, and sample thickness. Likewise a model based on many‐body effects, although explaining some of the features of the results, does not fit all the data. It is possible that a contribution to the impurity induced linewidth which is frequency dependent would provide a better fit and it is concluded that to fully interpret the data a more complex theory is necessary.

The effects of different microstructures on the formation of dislocation loops in aluminium during electron irradiation

Abstract Exposure to the beam in a 200kV electron microscope caused defect clusters to form in high-purity aluminium foils. The damage was due to the direct displacement of atoms by electrons. The point defect clusters nucleated randomly and grew to form dislocation loops. The microstructure of the aluminium was varied by quenching or alloying. In high-purity foils containing previously quenched-in Frank sessile vacancy loops the subsequent electron irradiation-induced defects were seen to interact with the pre-existing defects. In 99% aluminium and in 2024 aluminium (4.5%Cu, 1.5%Mg, 0.6%Mn, balance Al) no electron-induced damage was seen. However, when the 99% aluminium specimens were first neutron irradiated, subsequent bombardment by electrons caused the development of visible dislocation loops. The important conclusion of this electron microscope study is that the presence and distribution of electron irradiation damage in aluminium is extremely sensitive to microstructure.

The mechanism of prismatic dislocation loop formation in cyclically strained aluminium

Abstract Diffraction contrast theory has been applied to determine the nature of prismatic dislocation loops (i.e. vacancy and/or interstitial type) observed in high purity aluminium foils cyclically strained at 78°K. It has been established that both interstitial and vacancy loops are formed during cyclic straining. It is concluded that the only model of dipole formation consistent with these observations is the Gilman (1962) double cross-slip mechanism as modified by Fourie (1964).

Study on formation of dielectric film of super-purity Aluminium anode in electrolytic condenser (3rd report)

This report is on the experiment for obtaining the electrolytic condenser, which has higher electro-static capacity, shorter formation time and smaller leakage current, by use of super purity aluminium of 99.99% added with Ni, Cr, Co and V respectively.Findings are as follows:1) Addition of 0.003-0.018% Co to 99.99% Aluminium gives the best effect to the dielectric properties of the oxide film.2) Addition of Ni gives good effect, though a little, to those properties.3) Addition of Cr and V does not give any good effect.4) As has so far been made known by the writer, the recrystallized grain with {100} or {111} orientation shows higher electrostatic capacity compared with that with {110} orientation. The foil of high purity aluminium after added with Co and annealed has numorous {100} grains but no {110} one. On the other hand, the same foil added with V has {110} grains and few {100} grains.It was thus re-confirmed that the electrostatic capacity is mainly dependent on the orientations of recrystallized grains.5) Higher the annealing temperature, higher the electrostatic capacity can be obtained. But smaller the quantity of added element, more the effects for this purpose.The high purity aluminium foil added with Co shows higher electrostatic capacity regard-less of the temperature for annealing.It was found out, therfore, that 99.99% aluminium foil containing 0.008-0.02% of Co is easily etched and gives deeper pits and that this gives the best dielectric property to anode for the electrolytic condenser after formation at 500 volts.

高純度アルミ箔の結晶粒度が電解コンデンサーの陽極の性能におよぼす影響

It is not yet cleared whether the electrostatic capacity and leakage current of dielectric film is influenced or not by the grain size of high-purity aluminium foil which are used for anode of electrolytic condenser. The investigation was carried out with foils of 99.99% and 99.9% purities. Various grain sizes were obtained by the following methods. (1) After rolling with a heavy reduction from 1 mm to 0.1 mm (90%), the specimens 0.1 mm thick were annealed at various temperatures (250∼550°). (2) Initial sheets (0.125, 0.20, 0.40 mm) were rolled down to 0.1 mm in thickness. All the specimens were then annealed at 380° for 2 hrs and were etched electrolytically so that their weight was reduced by 24% each. Then it was found that the foil annealed at the end temperature of recrystallization (300∼320°), i,e, the foil of minimum grain size, has the maximum capacity in the experiment using the specimens of method (1). With the specimens of method (2), it was also ascertained that the foil with smaller grain size has the larger capacity, and the larger the capacity, the higher the leakage current is. If the grain size of 99.99% aluminium foils made by method (2), is so small as 0.1 mmφ, it would have a superior dielectric property with not less capacity and lower leakage current than 99.9% aluminium foil.

ON THE FABLICATING PROCESS AND THE PROPERTIES OF HIGH-PURITY ALUMINIUM FOIL (99.99%)

A description is given of present practice in the fabrication of high-purity aluminium foil used for electrolytic condenser. And the results of the author's experiments on the physical and electro-chemical properties of 99.99%Al are summarized compared with the ones of 99.9% Al in order to acquaint its property with consumers.