A novel method of manufacturing aluminum(Al)foil has been developed using electrodeposition in a sulfone-based organic electrolyte solution. The process produced excellent purity of Al higher than 99 wt% and reasonable thickness of greater than 8 μm. Moreover, the Al foil has good flexibility and high strength comparable to those of conventional Al foils produced using rolling methods. Results also show good mechanical strength at elevated temperatures. Characterization by XRD and SEM observation proved that the Al foil prepared using electrodeposition has specific orientation of the(111)crystal plane, which remained even after thermal treatment at temperatures as high as 300 ℃. These crystallographic characteristics are expected to be responsible for the good mechanical properties of this Al foil at elevated temperature, from which we can expect improved device performance in widely diverse applications.
The relation between the absorbed hydrogen contents and compressive stress in palladium deposits during cathodic electrolysis at current density of 4.0 mA/cm2 in 0.5 M H2SO4 was investigated. Using an electric balance, the amount of hydrogen absorbed in palladium and its evolution during electrolysis were evaluated quantitatively based on the buoyancy attributable to the hydrogen gas bubble. Variation of the internal strain with the absorption and desorption of hydrogen was also measured in situ using a resistance wire-type strain gauge placed on the reverse side of the copper substrate. Compressive strain with hydrogen absorption occurred immediately after cathodic electrolysis began. Then it relaxed spontaneously with desorption of hydrogen from the palladium deposits when the current was turned off. However, buoyancy attributable to the hydrogen gas bubble started after a considerably long elapsed time from application of cathodic electrolysis, which resulted from hydrogen absorption into palladium deposits. The variation of compressive stress with increasing hydrogen contents was described as Δσ/Δn(Hab), which was −4.6 kgfmm−2 mol%−1 in palladium deposits of 2.5-5.0 μm thickness.