关键词: 取向硅钢, 磷酸盐涂层, 低铬涂层, 耐腐蚀性能, 铁损

Abstract: Taking phosphate and ammonium metavanadate as the primary raw materials, a low-chromium phosphate coating solution was prepared for grain-oriented silicon steel with a magnesium silicate underlayer. Upon heat treatment at over 800℃, the prepared coating solution develops a compact and dense insulating film. Phase composition analysis reveals that the coating consists of amorphous oxides or composite oxides of aluminum, silicon, magnesium and vanadium, along with a small amount of phosphorus-containing oxysalts. The grain-oriented silicon steel specimen with low chromium insulating coating exhibit excellent corrosion resistance in 3.5%(mass fraction) NaCl solution. Polarization curve analysis shows that the self-corrosion potential of the low chromium coated sample is -0.563V, and its polarization resistance Rp is up to 24425.5Ω. Electrochemical impedance spectroscopy results demonstrate that the surface micropore resistance Rpo is 592.4Ω·cm2 and the charge transfer resistance is 20840.0Ω·cm2, respectively, which endows the material with favorable corrosion resistance. The average iron loss of grain-oriented silicon steel sheet is reduced by approximately 12.28% under the protection of the low-chromium insulating coating, which is comparable to that of the reference chromium coating.

Key words: grain-oriented silicon steel, phosphate coating, low-chromium coating, corrosion resistance, iron loss