For the purpose of brief analysis of degreasing process and adherent oil volume on degreased sample, a new technique was investigated by using Diethyl Dithio Carbamate Copper salt's oil solution (100mg/l as Cu). Oil on the sample was extracted by ultrasonic wave with 5 or 10ml n-Buthyl Acetate, and the amount of Cu in oil was determined by atomic absorption at 342.75nm. The results are as follows. 1) More than 10^-7g-oil/cm² on the sample was easily determined by this method. 2) On the degreasing process, Relations between Water covered area ratio (R) and Removed oil ratio (Y) were
Y+(C₁/R)=C₂
C₁=Tm/To, C₂=(To+Tm)/To
Tm: Thickness (μm) of oil film at R≅100%.
To: Oil film thickness (μm) before degreasing (R: 0%). Approximation of Tm was calculated by Stoke's equation and Einstein-Smoluchowski's equation as functions of Temperature and, Viscosity, Density, Degreasing time. 3) Distribution function of oil film thickness (X) was
F(X≥α)=1/(1+20R^3.4X^0.188_x+0.12)

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Absorption spectra were measured for aqueous and alcoholic (MeOH, EtOH, and n-PrOH) solutions of CrCl₃⋅6H₂O and the three hydrated isomers, [Cr(OH₂)₆]Cl₃, [Cr(OH₂)₅ Cl]Cl₂⋅H₂O and [Cr(OH₂)₄ Cl₂]Cl⋅2H₂O, and chromium (III) complex species existing in the above solutions were identified. It was found for the aqueous solutions that CrCl₃⋅6H₂O and the three isomers form violet colored hexaaquochromium (III) ions, [Cr(OH₂)₆]³⁺. In alcoholic solutions, however, all of CrCl₃⋅6H₂O and these hydrated Cr (III) chlorides form green colored dichlorotetraaquochromium (III) ions, [Cr(OH₂)₄ Cl₂]⁺. In alcoholic solutions, the absorption peak for [Cr(OH₂)₄Cl₂]⁺was found to shift gradually in the longer wavelength direction; this was interpreted in terms of the transformation from cis to trans structure and weak solvation by alcohol molecules. [Cr(OH₂)₆](ClO₄)₃ in aqueous and alcoholic solutions exists as [Cr(OH₂)₆]³⁺ giving a distinct blue-violet color.

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Porous oxide films with different thicknesses were formed on aluminum at a constant c.d. of 10mA/cm² in an oxalic acid solution. They were treated with hot water at 99.5°C, and the time-variation in the film structure due to hydration was followed by impedance measurements in a boric acid-borate solution. The frequency range examined was 0.1-10, 000Hz and the results were analyzed dusing a Bode diagram method in which the log of the absolute value of impedance was plotted against the log of the frequency. The equivalent circuit of the hydrated film was found to consist of the capacitance, C_b, of the barrier oxide layer, combined in series with a parallel combination of the capacitance and resistance components, C_h, and R_h, of the hydrated oxide in the pores. The values of these components were determined using the fact that C_b, R_h, and C_h are decisively responsible for the film impedance in the frequency range of<10, 10-500, and 500-10, 000Hz, respectively. For films thicker than 0.8μm (or anodizing time t_a>3min), 1/C_b, initially 6μF^-1·cm², decreases with the hydration time, t_h, and reaches a steady value of about 4.5μF^-1·cm² at t_h=10-20min. This indicates that the barrier layer thickness decreases with t_h due to hydration occur.ing from the outside and that the hydration reaction becomes extremely slow when the pores are filled up with hydrous oxide at time beyond t_h=10-20min. The 1/C_h value, corresponding to the thickness of the hydrous oxide phase increases with t_h for 10-20min to reach a steady value which is roughly propotional to the initial film thickness. The value of R_h is roughly propotional to t_a at any t_h but it continues to increase with t_h even after 1/C_h becomes steady, suggesting that the specific resistance of the formed hydrous oxide increases with time by an aging effect. For thin films formed for t_a=1min, oxide is completely hydrated within t_h=20min and thereafter the substrate metal gradually reacts with hot water. These findings are in agreement with the results of previous investigation, in which the weight gain of the films due to hydration was examined.

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