The behavior of AC impedance was measured in the anodizing of aluminum in sodium sulfate and sulfuric acid solution under electrode potentials from-1V to 10V versus Hg/Hg₂SO₄, sat. K₂SO₄ electrode at frequencies of 1mHz-100kHz. The equivalent circuit was analyzed using an impedance diagram (Cole-Cole plot) of the formation of barrier film and porous film on aluminum. A capacitive semicircle (A) and a reactive semicircle (B) were obtained in sodium sulfate solution, and another capacitive semicircle (C) also appeared in sulfuric acid solution. The diameters of circles A, B and C, which corresponded to resistance (R) for each reaction, tended to decrease with the increase of potential. Capacitance (C₁) calculated from circle A decreased with increases in potential. It was concluded that R was a response of the reaction and C₁ was a response of the capacitance of the barrier film. The value of C₁ in sodium sulfate solution was almost the same as the value in sulfuric acid solution. The circle A tended to change to two circles in impedance diagrams measured at-1.0V in sodium sulfate solution after anodization for 1hour at 10V in sulfuric acid solution, because the film thickness increased by anodizing and the resistance of the film was changed.

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The corrosion resistance of films deposited from electroless nickel plating baths was evaluated by outdoor-exposure tests, salt spray tests and an accelerated atmospheric corrosion (complex cycle) test under cycle conditions of 35°C in the test tank, 42min in 20-25ppm sulfurous acid gas ambient (<80% RH)→18min in 1% NaCl solution spray→102min in moisture (>85% RH)→78min in dry condition, for a total of 4 hours/cycle.
Deposited films that contained above 10% P content obtained from pH4.3 malic acid baths were superior under both outdoor-exposure tests and the accelerated corrosion test. A correlation was recognized between air temperature, humidity, and wetness time as weather factors in the outdoor-exposure test on the one hand and corrosion loss on the other. Absolute humidity was found to have a cleared effect than relative humidity on corrosion resistance. Since the salt spray test for electroless nickel plating showed a poor correlation to the corrosion pattern in the atmosphere and required a long period for corrosion to begin, this method was not suitable for corrosion test of the deposited films. On the other hand, specimens corroded in 4 cycles of the accerelated atmospheric corrosion test were found to have surface appearance similar to that of specimens in the outdoor-exposure test and the pits produced were uniform in size and distribution over the surface.

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Discharge characteristics in planar magnetron sputtering systems have been studied through target erosion patterns. The erosion pattern was affected not only by magnetic flux distribution but also by discharge power and sputtering gas pressure. A model analysis revealed that this behavior was due to interaction between the vertical component of the field and electrons moving in a transverse direction. A definite correlation with the pattern was found, indicating that the transition in the discharge characteristic from magnetron mode to high impedance mode was brought about by the escape of trapped electrons from the target edge.

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