著者

新藤 恵美 吉田 明 松本 誠臣

出版者

The Surface Finishing Society of Japan

雑誌

表面技術 (ISSN:09151869)

巻号頁・発行日

vol.51, no.6, pp.633-639, 2000-06-01 (Released:2009-10-30)

参考文献数

8

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Chemical polishing solutions for aluminum based on mixtures of phosphoric and nitric acid cause air pollution with hazardous gaseous emissions, such as NOx, during the chemical polishing process, and cause water pollution due to the effluent of wastewater that contains phosphates and nitrates. Hence, the authors attempted to polish aluminum in an alkaline solution containing sodium hydroxide as an alkaline agent and sodium persulfate as an oxidizing agent. In this process, exceptionally bright surfaces of aluminum were obtained; that is, the brightness of the surface polished in the alkaline solution was comparable with that of the surface polished in an acid chemical polishing solution. The composition of the alkaline solution that had the least polishing effect had a concentration of sodium hydroxide in a range of 0.5 to 1.5% by weight for pure aluminum and a range of 1.0 to 2.0% by weight for commercially pure aluminum, while the concentration of sodium persulfate was 35% by weight. At with a high magnification on a scanning electron microscope (SEM), network patterns were observed over the entire polished surface of the aluminum polished in the alkaline solution and that in the acid chemical polishing solution. On the surface of the commercially pure aluminum polished in the alkaline solution, very small projections were observed by SEM, that were identified by electron probe microanalysis (EPMA) as insoluble phases that included foreign elements such as Fe and Si in the aluminum. On the other hand, on the surface of the aluminum polished in the acid chemical polishing solution, very small pits were observed, formed by dissolution of the phases in the acid solution. Also, use of x-ray photoelectron spectroscopy (XPS) and fourier transform infrared spectroscopy (FT-IR) indicated that the oxide films formed on the surface of the aluminum polished in the alkaline solution were thicker and contained a larger amount of hydroxyl radicals than those on the surface polished in the acid chemical solution.