The so-called "Alodine" process is aluminum and aluminum alloy using chromium phosphate treatment technology, phosphate solution is mainly composed of phosphate phosphate and hexavalent chromium composition, generally also add fluoride ions. The phosphate film formed is emerald green, with good compatibility and corrosion resistance with the paint.
Alodine anodic oxidation treatment is a kind of aluminum alloy surface treatment, mainly used to improve the corrosion resistance of the aluminum alloy structure and the ability to bond with the primer. Alodine a kind of aluminum alloy surface treatment of the trade name, can be in the aluminum alloy surface through chemical reaction, to produce very thin (0.5 ~ 4 micron) anodic oxidation film. The principle of Allodin anodizing is a chromate passivation chemical reaction. The main components of Allodin are chromic anhydride, methyl tetrafluoroborate, sodium fluoride and other substances mixed in a certain proportion.
The purpose of using Allodin:
1. Improve the corrosion resistance of aluminum alloy surface.
2. Improve the adhesion with primer.
3. Can be used as a coating to change electrical conductivity.
Commonly used Allodin and its use:
1. Allodin 600, powder, is used on structural surfaces of fuel tanks coated with flame-resistant paint (BMS10-20), and is recommended for generating oxidized films with low resistivity. Color: yellow.
2. Allodin 1000, concentrate, for clad aluminum structural parts that do not require painting. Color: colorless.
3. Alodine 1200/1200S, powder, most commonly used for cut or filed repair parts, has good corrosion resistance and provides good bonding properties. Color: light gold to brownish yellow
4. Alodine 1500, powder, color: colorless
Characteristics of Alodine:
1. Generated by the oxide film is thin 0.5 ~ 4 microns, soft, porous, good adsorption properties, does not change the mechanical properties of the material, does not affect the dimensions of the workpiece, usually used as a primer for paint or other coatings.
2. Short operation time, a few minutes to an hour. No power consumption, simple equipment, low cost.
3. Alodine oxidation still has a certain conductivity.
4. Allodin process is mainly carried out at room temperature, low energy consumption, less pollution.
5. Allodin solution is stable, long-lasting, easy to maintain, and suitable for large-scale continuous production.
6. Allodin solution is toxic, can not contact with the human body, can not be disposed of arbitrarily, must be fully diluted and scrapped.
7. Allodin is flammable and should be kept away from fire. Fabrics that have been used with Allodin solution should also be isolated to avoid catching fire.
About the use of Allodin and precautions
I. The precautions for coating Allodin are:
1) Usually Allodin is packaged in powder form when it is sold, and before using it, you need to mix it into a certain concentration of acidic aqueous solution
liquid (1 gallon of water plus 3 ounces of 600 powder of Allodin) and leave it to stand for at least one hour before you can apply it. .
2) Special care must be taken during application, as it is a strong oxidizing agent and a carcinogen, so it should not be allowed to come into contact with the working
person's five senses and other exposed areas. In the process of use and configuration, must wear a gas mask, rubber or polychloroprene gloves;
3) If the eye contact can not be rubbed immediately rinse with water for 15 minutes, and promptly go to the hospital for treatment. Other parts of the body rinse with plenty of water and go to the hospital for treatment;
4) Alodine should be kept away from fire, heat and sparks. It should be kept in isolation from other substances. It should be sealed and well ventilated. Rags that have been used with Allodin solution can easily cause fire after drying. Therefore, it must be rinsed with water immediately and stored in a container with fresh water. Allodin powder can cause sparks if it comes into contact with strong acids. Therefore Allodin solution should be prepared in the designated place.
5) Select stainless steel or acid-resistant plastic or rubber (preferably polyethylene) containers to place the Allodin containers prohibit the use of glass and lead products and paper cups.
6) Allodin solution must be diluted with a large amount of water before scrapping, otherwise it will cause contamination.
II. The general procedure for applying Allodin is as follows:
1) Using a cleaning brush or rag, clean and remove the liquid grease solvent from the damaged surface and dry the surface with hot air or wipe it dry.
2) Remove surface debris with tools such as aluminum oxide sandpaper or emery cloth until a clean and smooth aluminum surface is obtained.
3 )? Rub the surface and clean the surface with a MEK moistened (not soaked) cotton cloth until no remaining particles are found on the cloth.
4) Allow the surface to dry for at least 15 minutes and perform a water film test to ensure that the surface is clean as required.
5) While keeping the surface wet, apply an ample coat of Allodin by brush or spray, allowing the solution to remain on the surface until a particular color is found (after about 30 seconds). Keep the area moist with a piece of cotton cloth with a small amount of solution (there is an easily visible color that can range from light yellow iridescent to tan, you can apply the color to make an identification, but applying Allodin 600 can have little or no color). Be careful not to let the Allodin solution dry out until the surface color changes.
6) Rinse the surface carefully with a clean cotton cloth and water. Be careful as you dry the surface not to remove the coating nor create scuffs on the surface. Gently go over the excess liquid with a clean, dry cotton cloth until there is no liquid at all.
7) Air dry the surface. (typically 1 to 3 hours). Note that drying is best done at 120F, and the maximum temperature should not exceed 130F. Wear clean gloves when touching the part or surface, and keep the part or surface dry and clean to prevent the surface from being contaminated.