Surfactant degreasing velocity is decided by oil globule diameter and it's distribution in boundary film. The velocity expression thus obtained, calculated the good values, but expressed no physical factor effects. These effects were studied using dimensional analysis. The degreasing velocity of a surfactant forming a stable emulsion is summarized as follows; (1/R-1)=C·F(Cx/Omax)·(Teη)/(tV2(d1-d2)2)0.7-1.0 F(Cx/Omax)≈1+0.5(Cx/Omax) R: water wetting area ratio, Te: bath temperature, Cx: oil concentration, Omax: maximum oil concentration for degreasing, V: agitation velocity, t: time, d1-d2: difference in oil and degreasing solution density, η: viscosity. Increasing Te and V greatly increased Omax. In high temperature and agitation velocity, degreasing velocity in little oil contamination was same as the initial bath.
Pit initiation and propagation in high-purity aluminum foils during etching with 5Hz rectangular alternating current (AC) in 1mol/dm3 hydrochloric acid solution at 30°C were studied based on potential changes and TEM observation of pit structures. High-purity aluminum foils containing 1 and 6 wt-ppm titanium were used, and titanium effects on pit propagation were discussed. Films stripped from etched foils by immersion in I2/methanol solution and samples prepared by jet electropolishing were used for TEM observation. Cubic pits formed at subgrain boundaries after one AC cycle. Pits varied from hemispherical to cubic during the first anodic half cycle, and a hydrous oxide etch film formed during the next cathodic half cycle. The cyclic voltammogram obtained through polarization in hydrochloric acid solution showed that titanium in high-purity aluminum foil accelerated hydrogen evolution in pits.
The effects of surface dissolution of high-purity aluminum foils for electrolytic capacitors during immersion in hot hydrochloric acid on distributions of pits initiated by direct current (DC) etching are discussed. Pit structures were observed with TEM of oxide films stripped from etched foils in I2/methanol solution. Anodized oxide film replicas were prepared for SEM to observe pit distribution. γ-Al2O3 crystals with sizes of 0.2-0.3μm were observed on rolling lines of oxide films. With increasing electrolyte immersion time before DC etching, areas of surface dissolution of aluminum foils around γ-Al2O3 crystals expanded. When immersion time was prolonged from 0s to 60s, pits were initiated uniformly because of the increase in active sites. Excess active sites on surfaces formed above 60s delayed tunnel pit growth.
Fine-pattern coils were fabricated on an insulating board using anodizing, laser irradiation, nickel deposition, insulating board sticking, and aluminum substrate dissolution. Aluminum specimens covered with porous anodic oxide films were irradiated by a pulsed Nd-YAG laser through a beam splitter, iris diaphragm, convex lens, and quartz window in a nickel electroplating solution to remove anodic oxide film. During laser irradiation, the specimen was moved 3-dimensionally with an XYZ stage by a personal computer. The width of the trench produced by film removal increased with increasing laser energy and with decreasing movement speed. After laser irradiation, nickel metal layer was electrodeposited at only the laser irradiated area by cathodic polarization. The specimen stuck on epoxy resin before dissolving the aluminum substrate. Fine pattern coils with nickel lines 15μm wide and at 25μm intervals were made on the insulating board.
Experiments were undertaken to determine the dependence of zinc-nickel alloy plating electrodeposition and composition distribution from sulfate solutions on surfactants. We found that deposits with dodecyltrimethylammonium chloride (DTAC) formed the nickel concentration layer in the iron substrate. This nonuniform composition will be attributed to adsorption of the cationic DTAC on the cathode during electrodeposition.