THE STUDY OF ELECTROLYTIC COLORING IN SILVER NITRATE SOLUTION AFTER THE SECOND ANODIC TREATMENT OF ALUMINUM SHEET

• Main Authors: Chia-wei Huang, 黃家緯
• Other Authors: Hsing-Hsiang Shih
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/vagr9h

碩士 === 大同大學 === 化學工程學系(所) === 95 === The aluminum materiel can produce plane film with larger pores after the secondary anodic treatment. The application of silver nitrate as the electrolytic solution of the electrolytic coloring has the advantage of obtaining pure black anodic film by applying low coloring voltage, short time and dilute concentration. In this research, effects of using respectively silver nitrate and copper sulfate in the electrolytic solution for the electrolytic coloring after the secondary anodic treatment are investigated and the comparison of the properties of the film after coloring are studied. The results show that by applying silver nitrate as the electrolytic solution at an electrolytic voltage of 15Vac, the lowest L-value can be obtained; besides, a-value and b-value approach to zero, the aluminum oxide film has the effect of being in near to purely black. Both the coloring time and the voltage do not have any effect on the film thickness, whereas, it’s the current density of the anodic treatment that has the effect on the thickness of the film. As for the hardness, the larger the electrolytic coloring time or the larger the electric voltage, the hardness of the aluminum oxide film would be worse. With SEM it is known that larger and more pores are produced from secondary anodic treatment than those from primary anodic treatment, and that large quantity of metal ions precipitates into pores on the surface of the coloring film. As for the reflectivity, it is measured that with the silver nitrate solution for the electrolytic coloring, the reflectivity within the range of 600~700 nm is lower than that with the copper sulfate solution. From the dissolution film test, it is known that stronger structure can be obtained by using silver nitrate in the electrolytic solution. Furthermore, according to the corrosion test, better anticorrosion effect can be obtained by using silver nitrate solution for the electrolytic coloring and that the best anticorrosion effect occurs at the anodic current density of 2A/dm2. Through the secondary anodic treatment at the anodic current density of 2A/dm2, by applying silver nitrate as the electrolytic solution, under the coloring voltage of 15Vac and coloring time of 15 min, these are the best operating conditions to obtain a black film with △E value of 9.60, L-value of 9.56, a-value of 0.83, b-value of -0.09, and the lowest reflection of 5.55% within the visible light of 580 nm. Therefore, the best absorption effect is obtained.