We have studied and explored the most commonly used sealing method of aluminum alloy anodic oxide film. Now let’s explain the coloring and closing principle of hard anodic oxide film. The current hardware industry products are not a single color, they have been beautified, how are these colors plated? After reading the following analysis, I believe we will understand:
The fresh oxide film obtained after anodization can be colored in time, which not only beautifies the appearance of the oxide film, but also increases the corrosion resistance. The oxide film of pure aluminum, aluminum-magnesium alloy and aluminum-manganese alloy is easy to dye into various colors, while the oxide film of aluminum-copper and aluminum-silicon alloy is dark and can only be dyed dark.
The aluminum and aluminum alloys are put into the organic-rich electrolyte for anodic coloring treatment, and they are also colored at the same time of anodic oxidation. color. Aluminum oxidation processing equipment is simple, easy to operate, high production efficiency, does not consume electricity, has a wide range of applications, and is not limited by the size and shape of parts. The oxidation process can be divided into two categories: alkaline oxidation method and acid oxidation method according to its solution properties. The fine particles come from the base metal or the differentiated products of organic matter in the electrolyte, and the color depth is directly related to the thickness of the film. This technology requires high anode current density and high voltage, so the energy consumption is large.
After aluminum and aluminum alloys are anodized, they are then put into a solution rich in nickel salts, diamond salts, tin salts or copper salts for communication and electrolysis, so that metal nickel, cobalt, tin or copper are deposited on the bottom of the membrane hole, showing the appearance. different colors. The full name of hard anodizing is hard anodizing. Hard anodizing of aluminum alloys is mainly used for engineering or military purposes, and it is suitable for both deformed aluminum alloys and more likely for die-cast alloy parts. The technology has the characteristics of simple technology, low energy consumption, uniform coloring and high production efficiency. The electrolytic coloring technology of aluminum and aluminum alloys is listed.
Because the oxide film has porosity and strong adsorption ability, it can dye different colors. The most suitable oxide film for direct coloring is the anodic oxide film obtained from sulfuric acid solution, which makes most aluminum and aluminum alloys form a colorless and transparent film with suitable thickness, porosity and adsorption. The oxalic acid anodic oxidation technology is more expensive than the sulfuric acid technology, and a yellow film is obtained. When the film layer exceeds 50μm, a natural yellow or brown color is obtained. Chromic acid anodizing technology is usually not suitable for coloring because of its thin film, less pores, and its own gray color. The requirements of coloring on the oxide film are suitable film thickness, sufficient pores and excellent adsorption capacity, no trauma and pollution.