Why many manufacturers choose to use nickel-free phosphating agent for phosphating treatment

Many manufacturers will choose to use nickel-free phosphating agent for phosphating treatment before painting metal. Why do you do this? What is the function of phosphating agent? The editor helps you answer.

Phosphating agent mainly forms a layer of phosphating film on the metal surface through chemical reaction to improve the corrosion resistance of metal products. It can also play a role in rust prevention and antirust wax on the metal surface, and improve the adhesion of paint spraying, so the metal will choose to undergo phosphating treatment before painting.

Phosphating treatment

A layer of non-metallic, non-conductive, porous and continuous phosphate film is formed on the metal surface through chemical reaction. The main component of phosphate is acid phosphate. These acid phosphates, after being dissolved in water, decompose to produce free phosphate, react with the metal on the surface of the workpiece, and form phosphate deposits on the surface of the workpiece. The phosphating film is formed.

Phosphating film action

A. The phosphating film is a crystalline accumulation of phosphate, with porous and unsmooth surface, which can penetrate into these pores, thus significantly improving the adhesion of the coating film.

B. The phosphating film can transform the metal surface from a good conductor to a bad conductor, thus inhibiting the galvanic cell corrosion on the metal surface and improving the corrosion resistance and water resistance of the coating.