Phosphate coating, one of the best primers

Phosphate coating is a process for preparing iron, steel, galvanized, and aluminum surfaces using a dilute solution of phosphoric acid and other chemicals. In this coating method, the metal surface reacts with the acid solution to form a protective layer of phosphate crystals on the surface.

What is phosphate?

Phosphate coatings are formed on the metal surface by the reaction of phosphate ions. The mechanism of action is that an acidic solution containing iron or zinc phosphate is sprayed or immersed into the part. In the interface between the solution and the surface, the pH increases, and as a result of this increase, phosphate crystals precipitate on the surface. The coating is formed by the precipitation of these crystals. Phosphates form a layer on the metal surface that, on the one hand, makes the surface resistant to corrosion and, on the other hand, creates a stronger bond between the paint and the metal.

In fact, a phosphate coating is formed by the reaction of a metal with a chemical solution. Usually the metals are iron, zinc or manganese. The reaction to form a phosphate coating is an acid-base reaction. When the metal is placed in the presence of phosphoric acid, the phosphate deposits on the metal surface and forms a colored coating. Coatings include manganese phosphate, iron phosphate, chromate, dicationic zinc phosphate (dip and spray), tricationic zinc phosphate (used in ED paint lines and dip and spray), and nano coating. After degreasing and also after phosphating, it is necessary to rinse with suitable water.