FIELD: protective coatings.
SUBSTANCE: group of inventions relates to a means for forming a chrome-free insulating coating on the surface of a textured sheet of electrical steel, a textured sheet of electrical steel with an insulating coating applied and a method for its manufacture. The means for forming a chromium-free insulating coating contains a component (A) selected from at least one of the phosphates: Mg, Ca, Ba, Sr, Zn, Al and Mn, component (B) in the form of colloidal silicon dioxide, component (C) selected from at least one of the salts of organic acids: Mg, Ca, Ba, Sr, Zn, Al, Mn, Fe, Ni, Cu and Co, and component (D) in the form of phosphoric acid, and has a pH of less than 4.5. Component (B) is contained in an amount of 50 to 150 weight parts in terms of solid SiO2. Component (C) is contained in an amount of 5.0 weight parts or more in terms of a metal element, while quantities are obtained by calculating 100 weight parts in terms of the solid substance of component (A). Component (D) is contained in such an amount that the molar ratio between M2+ and M3+, each of which is a metal element in the processing medium to form a chromium-free insulating coating, and elemental phosphorus P satisfies the expression 0.50 < (M2+ + 1.5 × M3+)/P ≤ 1.20, where M2+ is at least one of Mg, Ca, Ba, Sr, Zn, Mn, Ni, Cu and Co, and M3+ is at least one of Al and Fe.
EFFECT: invention provides the creation of a textured sheet of electrical steel with an insulating coating applied, including a chrome-free insulating coating characterized by high coating tension, high resistance to moisture absorption and high anticorrosive resistance.
7 cl, 1 dwg, 5 tbl, 4 ex
