Preparation and characterization of manganese phosphate chemical coating on bearing steel

• 1、School of Metallurgy and ecological engineering, University of Science and Technology Beijing

Abstract：This article mainly introduces the preparation of manganese phosphate coating on the surface of bearing steel GCr15SiMn using chemical conversion method. The effects of different temperatures, solution pH, and phosphating time on the microstructure and morphology, film weight, and corrosion resistance of manganese phosphate coatings were studied using SEM, XRD, and electrochemical analysis. The results indicate that increasing the temperature is beneficial for promoting the growth of the film layer. When the solution is 80 ℃, the film weight is 23.6g/m2, and the polarization resistance of the phosphating film is 77074 Ω cm2, indicating good corrosion resistance. A low pH of the solution is not conducive to the formation of the film layer. When pH=2, the film weight is the largest, and the corrosion resistance is good. The corrosion potential is -0.515V, and the corrosion current density is 4.293 × 10-7A/cm2。 As the phosphating temperature increases, the growth rate of the phosphating film slows down. When the phosphating time is 20 minutes, the film weight is 23.8g/m2, and the corrosion current density is 7.391 × 10-8A/cm2, with good corrosion resistance.

Keywords： Manganese phosphate coating Corrosion resistance Membrane weight polarization curve