Method for producing a steel product with a Zn coating and a tribologically active layer deposited on the coating, and a steel product produced according to said method

摘要

A process for producing a steel product having a protective coating based on zinc and a tribologically active layer applied to the protective coating where the process includes providing a flat steel product provided with the protective coating, and applying an aqueous solution comprising ammonium sulfate and demineralized water to the protective coating of the steel product. The concentration of the ammonium sulfate based on the SO₄²⁻ ions is 0.01-5.7 mol/L, the pH of the aqueous solution is 4-6, and the near-surface reaction time between the aqueous solution and the protective coating is more than 0 seconds and not more than 5 seconds. After a drying operation conducted without preceding rinsing, a tribologically active layer consisting of ammonium zinc sulfate is formed atop the protective zinc coating. Also, a steel product having a protective coating based on zinc and a tribologically active layer of ammonium zinc sulfate.