After the metal (mainly steel) is treated with a solution containing phosphate such as zinc (Zn), manganese (Mn), chromium (Cr) and iron (Fe), an insoluble phosphate film is formed on the surface of the base metal. This process is called phosphating.
After degreasing and derusting the metal surface, in order to prevent it from rusting again, chemical treatment is usually carried out to form a protective film on the metal surface, which is usually only a few microns, mainly to enhance the adhesion between the coating and the substrate, and a thicker film layer can also enhance the antirust performance.
Extended data:
According to the phosphating film-forming system, it can be divided into six categories: zinc system, zinc-calcium system, zinc-manganese system, manganese system, iron system and amorphous iron system.
According to the thickness (weight) of phosphating film, it can be divided into four categories: sub-lightweight, lightweight, sub-heavyweight and heavyweight.
The weight of the second light film is only 0. 1 ~ 1.0g/m2. Generally, it is an amorphous iron-based phosphating film, which is only used for priming before painting, especially for large deformation workpieces.
Lightweight film weight 1. 1 ~ 4.5 g/m2 is widely used for priming before painting, but it is seldom used in anticorrosion and cold working industries.
The film thickness of secondary heavy phosphating is 4.6 ~ 7.5 g/m2, which is thicker (generally >: 3μm) because of its heavy weight. It is rarely used as a primer before painting (only for steel parts that are basically not deformed), and can be used for anticorrosion and cold working to reduce friction and lubrication.
Heavy film is above 7.5 g/m2, and no primer is used before painting, so it is widely used for anticorrosion and cold working.
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