Non-oriented electrical steel sheet and manufacturing method thereof

Abstract

An inorganic-organic composite film is formed by coating a application liquid containing an inorganic component and an organic resin on a surface of a steel sheet, and baking the application liquid on the surface of the steel sheet. The application liquid contains phosphate as the inorganic component, and further contains an inorganic powder having a BET specific surface area of 10 m 2 /g or more and exhibiting a particle size distribution with a 50% cumulative particle size of 5 μm or less and with a 90% cumulative particle size of 15 μm or less when measured by a laser diffraction particle size analyzer, the powder being contained at a ratio of no less than 1 mass %, nor more than 50 mass % with respect to a solid content of the phosphate.

1 . A manufacturing method of a non-oriented electrical steel sheet, comprising:
 coating an application liquid which contains an inorganic component and an organic resin on a surface of a steel sheet; and   forming an inorganic-organic composite film by baking the application liquid on the surface of the steel sheet,   wherein the application liquid contains phosphate as the inorganic component, and   wherein the application liquid further contains an inorganic powder having a BET specific surface area of 10 m 2 /g or more and exhibiting a particle size distribution with a 50% cumulative particle size of 5 μm or less and with a 90% cumulative particle size of 15 μm or less when measured by a laser diffraction particle size analyzer, the powder being contained at a ratio of no less than 1 mass %, nor more than 50 mass % with respect to a solid content of the phosphate.   
     
     
         2 . The manufacturing method of a non-oriented electrical steel sheet according to  claim 1 , wherein the application liquid does not contain a chromate-based compound. 
     
     
         3 . The manufacturing method of a non-oriented electrical steel sheet according to  claim 1 , wherein the application liquid contains, as the inorganic powder, at least one kind selected from a group consisting of alumina powder, silica powder, magnesia powder, titania powder and zirconia powder. 
     
     
         4 . The manufacturing method of a non-oriented electrical steel sheet according to  claim 2 , wherein the application liquid contains, as the inorganic powder, at least one kind selected from a group consisting of alumina powder, silica powder, magnesia powder, titania powder and zirconia powder. 
     
     
         5 . The manufacturing method of a non-oriented electrical steel sheet according to  claim 1 , wherein the application liquid is formed of a mixed solution of an aqueous aluminum biphosphate solution and an aqueous dispersion of organic resin, and the inorganic powder. 
     
     
         6 . The manufacturing method of a non-oriented electrical steel sheet according to  claim 2 , wherein the application liquid is formed of a mixed solution of an aqueous aluminum biphosphate solution and an aqueous dispersion of organic resin, and the inorganic powder. 
     
     
         7 . The manufacturing method of a non-oriented electrical steel sheet according to  claim 3 , wherein the application liquid is formed of a mixed solution of an aqueous aluminum biphosphate solution and an aqueous dispersion of organic resin, and the inorganic powder. 
     
     
         8 . The manufacturing method of a non-oriented electrical steel sheet according to  claim 4 , wherein the application liquid is formed of a mixed solution of an aqueous aluminum biphosphate solution and an aqueous dispersion of organic resin, and the inorganic powder. 
     
     
         9 . The manufacturing method of a non-oriented electrical steel sheet according to  claim 1 , wherein a temperature at the baking the application liquid on the surface of the steel sheet is set to 270° C. or higher. 
     
     
         10 . The manufacturing method of a non-oriented electrical steel sheet according to  claim 2 , wherein a temperature at the baking the application liquid on the surface of the steel sheet is set to 270° C. or higher. 
     
     
         11 . The manufacturing method of a non-oriented electrical steel sheet according to  claim 3 , wherein a temperature at the baking the application liquid on the surface of the steel sheet is set to 270° C. or higher. 
     
     
         12 . The manufacturing method of a non-oriented electrical steel sheet according to  claim 4 , wherein a temperature at the baking the application liquid on the surface of the steel sheet is set to 270° C. or higher. 
     
     
         13 . The manufacturing method of a non-oriented electrical steel sheet according to  claim 5 , wherein a temperature at the baking the application liquid on the surface of the steel sheet is set to 270° C. or higher. 
     
     
         14 . The manufacturing method of a non-oriented electrical steel sheet according to  claim 6 , wherein a temperature at the baking the application liquid on the surface of the steel sheet is set to 270° C. or higher. 
     
     
         15 . The manufacturing method of a non-oriented electrical steel sheet according to  claim 7 , wherein a temperature at the baking the application liquid on the surface of the steel sheet is set to 270° C. or higher. 
     
     
         16 . The manufacturing method of a non-oriented electrical steel sheet according to  claim 8 , wherein a temperature at the baking the application liquid on the surface of the steel sheet is set to 270° C. or higher. 
     
     
         17 . A non-oriented electrical steel sheet, comprising
 an inorganic-organic composite film formed on a surface,   wherein said inorganic-organic composite film contains:   phosphate; and   an inorganic powder having a BET specific surface area of 10 m 2 /g or more and exhibiting a particle size distribution with a 50% cumulative particle size of 5 μm or less and with a 90% cumulative particle size of 15 μm or less when measured by a laser diffraction particle size analyzer, and   wherein a content of the inorganic powder is no less than 1 mass %, nor more than 50 mass % with respect to a solid content of the phosphate.   
     
     
         18 . The non-oriented electrical steel sheet according to  claim 17 , wherein said inorganic-organic composite film does not contain a chromate-based compound. 
     
     
         19 . The non-oriented electrical steel sheet according to  claim 17 , wherein said inorganic-organic composite film contains, as the inorganic powder, at least one kind selected from a group consisting of alumina powder, silica powder, magnesia powder, titania powder and zirconia powder. 
     
     
         20 . The non-oriented electrical steel sheet according to  claim 18 , wherein said inorganic-organic composite film contains, as the inorganic powder, at least one kind selected from a group consisting of alumina powder, silica powder, magnesia powder, titania powder and zirconia powder. 
     
     
         21 . An application liquid for a non-oriented electrical steel sheet, containing:
 phosphate as an inorganic component; and   an inorganic powder having a BET specific surface area of 10 m 2 /g or more and exhibiting a particle size distribution with a 50% cumulative particle size of 5 μm or less and with a 90% cumulative particle size of 15 μm or less when measured by a laser diffraction particle size analyzer, the powder being contained at a ratio of no less than 1 mass %, nor more than 50 mass % with respect to a solid content of said phosphate.   
     
     
         22 . The application liquid for a non-oriented electrical steel sheet according to  claim 21 , wherein a chromate-based compound is not contained. 
     
     
         23 . The application liquid for a non-oriented electrical steel sheet according to  claim 21 , wherein at least one kind selected from a group consisting of alumina powder, silica powder, magnesia powder, titania powder and zirconia powder is contained as said inorganic powder. 
     
     
         24 . The application liquid for a non-oriented electrical steel sheet according to  claim 22 , wherein at least one kind selected from a group consisting of alumina powder, silica powder, magnesia powder, titania powder and zirconia powder is contained as said inorganic powder.