CONVERSION LIQUID FOR FORMING A CONVERSION COATING ON THE SURFACE OF NON-TEXTURED SILICON STEEL AND A METHOD FOR ITS MANUFACTURING

Claims

1. A conversion liquid for forming a conversion film on the surface of non-textured silicon steel, wherein the conversion liquid is acidic and has a solid fraction content of 10-30 wt.%, wherein the solid fraction includes: an inorganic component of the conversion film, selected from at least one material of titanium, zirconium, hafnium and silicon fluorides, and having a content in mass percentage of 1-10 mass% in the conversion liquid; an aqueous organic resin having a mass percentage content of 0-20% by weight in the conversion liquid.

2. The conversion liquid according to paragraph 1, in which the solid fraction of the conversion liquid consists of: an inorganic component of the conversion film, selected from at least one material of titanium, zirconium, hafnium and silicon fluorides, and having a content in mass percentage of 1-10 mass% in the conversion liquid; aqueous organic resin having a mass percentage content of 0-20% by weight in the conversion liquid.

3. The conversion liquid according to claim 1 or 2, wherein the inorganic component of the conversion film comprises at least titanium fluoride and / or zirconium fluoride.

4. The conversion liquid according to claim 1 or 2, in which the solid fraction content of the conversion liquid is 15-20 wt.%; and / or the pH value of the conversion liquid is 2-4.

5. The conversion liquid according to claim 1 or 2, wherein the aqueous organic resin is selected from water-soluble phenolic resins, water-soluble polyester resins and water-soluble polyurethane resins.

6. The conversion liquid according to claim 1 or 2, wherein the solid fraction further comprises an additive, wherein the additive comprises: a phosphate agent and / or a silicon-based auxiliary agent.

7. The conversion liquid according to claim 6, wherein the phosphate is selected from at least one of Mn, Fe and Co phosphates.

8. The conversion fluid according to claim 6, wherein the silicon-based auxiliary agent is selected from a nanosized SiO2 sol and / or a silane coupling agent.

9. The conversion fluid according to claim 6, wherein the additive has a content of 2-15 wt.% in the conversion fluid.

10. A non-textured silicon steel comprising a silicon steel substrate and a conversion film disposed on the surface of the silicon steel substrate, wherein the conversion film is formed by a conversion liquid according to any one of claims 1 to 9.

11. Non-textured silicon steel according to claim 10, in which the Ti+Zr content in the conversion film is 1-800 mg / m3 2 ; and / or the silicon steel substrate contains, in addition to Fe and inevitable impurities, the following elements in mass percentages: Si: 1.0-3.3 wt.% and Al: 0.2-0.8 wt.%.

12. Non-oriented silicon steel according to claim 11, in which when 0.2 wt% ≤ (Si+Al) < 3.0 wt% in the silicon steel substrate, the Ti+Zr content in the conversion film is 80-800 mg / m 2 ; when 3.0 wt% ≤ (Si+Al) ≤ 4.5 wt% in the silicon steel substrate, the Ti+Zr content in the conversion film is 1-100 mg / m 2 .

13. Non-oriented silicon steel according to claim 12, in which when 0.2 wt% ≤ (Si+Al) < 3.0 wt% in the silicon steel substrate, the Ti+Zr content in the conversion film is 100-500 mg / m 2 .

14. Non-oriented silicon steel according to claim 12, in which when the Si+Al content in the silicon steel substrate is 3.0-4.5 wt.%, the Ti+Zr content in the conversion film is 3-50 mg / m 2 .

15. A method for forming a conversion film on the surface of a silicon steel substrate, comprising the following stages, performed sequentially: immersion, in which a silicon steel substrate is immersed in a conversion liquid according to any one of paragraphs 1-9, wherein the immersion time is 2-15 seconds, and the immersion temperature is 5-40°C; drying and curing, which carries out drying and curing of the silicon steel substrate to form a conversion film on the surface of the silicon steel substrate; optionally, applying an insulating coating on the surface of the conversion film to obtain a finished sheet of non-textured silicon steel; It is not necessary to clean the surface of the silicon steel substrate before performing the immersion step.

16. The method according to claim 15, wherein the immersion time is 3-8 seconds; and / or the immersion temperature is 15-30°C.

17. The method according to claim 15, wherein, at the immersion stage, the conversion liquid is placed in a conversion tank in which at least one pair of squeezing rollers is located at the inlet for squeezing residual water from the surface of the silicon steel substrate and at least two pairs of squeezing rollers are located at the outlet of the conversion tank for squeezing the silicon steel substrate immersed in the conversion liquid.

18. The method according to any one of paragraphs 15-17, in which the content of Ti+Zr in the conversion film is 1-800 mg / m 2 ; and / or the silicon steel substrate contains, in addition to Fe and inevitable impurities, the following elements in mass percentages: Si: 1.0-3.3 wt.% and Al: 0.2-0.8 wt.%.

19. The method according to paragraph 18, in which when 0.2 wt% ≤ (Si+Al) < 3.0 wt% in the silicon steel substrate, the Ti+Zr content in the conversion film is 80-800 mg / m 2 , preferably 100-500 mg / m 2 ; when 3.0 wt% ≤ (Si+Al) ≤ 4.5 wt% in the silicon steel substrate, the Ti+Zr content in the conversion film is 1-100 mg / m 2 , preferably 3-50 mg / m 2 .