Foszfátálás

Foszfátálás is a surface treatment process commonly used in metal finishing. It involves the chemical conversion of a metal surface, typically steel, aluminum, or zinc, into a protective layer of insoluble metal phosphates. This phosphated layer is not inherently corrosion-resistant but serves as an excellent base for subsequent coatings.

The process typically involves immersing the metal part in a hot acidic solution containing phosphoric acid and metal salts, usually zinc, iron, or manganese. The acid etches the metal surface, allowing the metal ions to react and form a crystalline phosphate coating. The type of metal phosphate formed depends on the specific metal ions present in the bath and the processing conditions. Zinc phosphate coatings are common for steel, offering good adhesion for paint and improved corrosion resistance. Manganese phosphate coatings are often used for wear resistance and lubrication. Iron phosphate coatings are simpler and less costly, primarily used for paint adhesion on steel.

Foszfátálás enhances the adhesion of organic coatings such as paints, lacquers, and powder coatings. The porous nature of the phosphate layer provides a good mechanical key for these coatings, preventing delamination and improving their overall durability. It also offers a degree of temporary corrosion protection, especially when combined with oils or waxes. The process is widely applied in the automotive industry, appliance manufacturing, and general metal fabrication to improve the performance and longevity of metal components.