THE INFLUENCE OF PRE-IMMERSING IN HIGH TEMPERATURE SOLUTION OF AMMONIUM MOLYBDATE ON THE ANODIC FILM OF ALUMINUM

• Main Authors: Kuei-Wei Chen, 陳瑰瑋
• Other Authors: Hsing-Hsiang Shih
• Format: Others
• Language: en_US
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/09525878014232758658

碩士 === 大同大學 === 化學工程學系(所) === 92 === The main purpose of this research is to study the effects of the ammonium molybdate concentration, immersing time and immersing temperature on the anodic films of aluminum sheets which was pre-immersed in the solution that contains ammonium molybdate and ammonium fluoride at high temperature. The higher immersing temperature surely promote the formation rate of molybdic oxyhydroxide film. Except the immersing temperature, the immersing time and ammonium molybdate concentration do effect the molybdic oxyhydroxide film thickness very much but not the anodic film thickness. Appropriate molybdic oxyhydroxide film thickness would be conducive to obtain a harder anodic film. But too thicker molybdic oxyhydroxide film will inhibit the growth of anodic film.From SEM, it can be known that the immersing temperature over 80℃ can not make the pores on the anodic film smaller and distributed uniformly. It’s not helpful for film hardness. The EDS analytic chart show that the molybdenum atom is found in the anodic film, it’s one reason why the anodic film microhardness increases. From ICP test, it also reveals that the concentration of Mo is helpful for the anodic film hardness. From corrosion test, the anodic film obtained through an immersing temperature of 80℃ has the best corrosion-resistance.Under the immersing conditions of 0.025 mol/L ammonium molybdate, 80℃, 40 min and an anodizing current density of 5A/dm2 (p.c.), a maximum anodic film microhardness of 627 HV can be obtained.