Aluminum is a metal used commonly for various applications. It is light and strong material that resists corrosion fairly well even without surface finish. Anodizing improves the corrosion resistance and yields economically a pleasant appearance in many different colors. The oxide layer is also very hard and provides a good wear resistant surface while retaining the pleasant, natural appearance of the metal. The anodized layer is a good electrical insulator as well.
Aluminum passivation is a reaction coating that remarkably improves the natural corrosion resistance of aluminum. Additionally, passivation secures a good electrical contact and acts as a good primer for painting.
Anodizing and passivation at Pinnoitus Helin Oy
- Sulphuric acid anodizing, natural color and black
- Hard anodizing
- Oxalic acid anodizing
- Ptfe impregnation
- Organic impregnation, colorless and opal white
- SurTec 650 chromitAl
- Iridite NCP
Different anodizing methods (sulphuric and oxalic acid and hard anodizing) differ from each other mainly by the diameter of the pores produced in the growing of the layer. Small pores mean higher quantity of aluminum oxide and thus harder coating. On the other hand the porosity of the surface can be utilized by impregnating it with different colors and ptfe particles. Also, metal (e.g. nickel) coating of the oxidized surface is easily possible. The metal coating can in this case be electrically connected to the base or disconnected from it. One typical application is the manufacturing of name plates by silk-screen or digital printing inside the anodized surface.
Organic impregnation is done electrophoretically with an anodic method where the charged particles are moved with electric current onto and into an oxidized surface. This method gives very good corrosion protection to aluminum even in chemically challenging objects. The impregnation is even, and it does not depend on the shape of the object; the results are visually very pleasant, with various colors.