Annealing separator for oriented electrical steel sheet, oriented electrical steel sheet, and manufacturing method of oriented electrical steel sheet

Abstract

An annealing separator for an oriented electrical steel sheet including: a first component includes a Mg oxide or a Mg hydroxide; and a second component including one kind among oxides and hydroxides of a metal selected from Al, Ti, Cu, Cr, Ni, Ca, Zn, Na, K, Mo, In, Sb, Ba, Bi, and Mn, or two or more kinds thereof.

1 . An annealing separator for an oriented electrical steel sheet, comprising:
 a first component including a Mg oxide or a Mg hydroxide; and   a second component including one kind among oxide and hydroxide of a metal selected from Al, Ti, Cu, Cr, Ni, Ca, Zn, Na, K, Mo, In, Sb, Ba, Bi, and Mn, or two or more kinds thereof,   wherein Equation 1 below is satisfied:
   0.05<[A]/[B]<10.5  [Equation 1]
 
   (in Equation 1, [A] is a content of the second component with respect to a total amount (100 wt %) of the annealing separator, and [B] is a content of the first component with respect to the total amount (100 wt %) of the annealing separator).   
     
     
         2 . The annealing separator for the oriented electrical steel sheet of  claim 1 , wherein the second component includes a Mn oxide or a Mn hydroxide. 
     
     
         3 . The annealing separator for the oriented electrical steel sheet of  claim 2 , wherein the second component is MnO 2 , and the first component is MgO. 
     
     
         4 . A manufacturing method of an oriented electrical steel sheet, comprising:
 a step of preparing a steel slab;   a step of heating the steel slab;   a step of hot-rolling the heated steel slab to manufacture a hot-rolled sheet;   a step of cold-rolling the hot-rolled sheet after annealing the hot-rolled sheet to manufacture a cold-rolled sheet;   a step of decarburizing and nitriding-annealing the cold-rolled sheet;   a step of coating an annealing separator on the surface of the decarburized and nitriding-annealed steel sheet;   a step of high temperature annealing the steel sheet to which the annealing separator is coated to obtain a primary film on the surface of the steel sheet; and   a step of obtaining an oriented electrical steel sheet,   wherein the annealing separator includes:   a first component including a Mg oxide or a Mg hydroxide; and   a second component including one kind among oxides and hydroxides of a metal selected from Al, Ti, Cu, Cr, Ni, Ca, Zn, Na, K, Mo, In, Sb, Ba, Bi, and Mn, or two or more kinds thereof, and satisfies Equation 1 below:
   0.05<[A]/[B]<10.5  [Equation 1]
 
   (in Equation 1, [A] is a content of the second component with respect to a total amount (100 wt %) of the annealing separator, and [B] is a content of the first component with respect to the total amount (100 wt %) of the annealing separator).   
     
     
         5 . The manufacturing method of  claim 4 , wherein in the step of the decarburization and nitriding-annealing of the cold-rolled sheet,
 an oxidation layer including a silicon oxide or an iron oxide is formed on the surface of the decarburized and nitriding-annealed steel sheet.   
     
     
         6 . The manufacturing method of  claim 5 , wherein in the step of high temperature annealing the steel sheet to which the annealing separator is coated to obtain the primary film on the surface of the steel sheet, the primary film is formed by the oxidation layer including: the silicon oxide or the iron oxide, the inside steel sheet, or a combination thereof; and the annealing separator. 
     
     
         7 . The manufacturing method of  claim 6 , wherein the second component of the annealing separator includes one kind, or two or more kinds, of the Mn oxide and hydroxide. 
     
     
         8 . The manufacturing method of  claim 7 , wherein the second component of the annealing separator is MnO 2 , and the first component is MgO. 
     
     
         9 . The manufacturing method of  claim 8 , wherein the primary film includes one kind among MnO, MnO 2 , MnO 3 , Mn 2 O 7 , Mn 2 O 3 , MnSiO 3 , Mn 2 SiO 4 , MnAl 2 O 4 , Mn 2 Al 4 Si 5 O 12 , Mn 3 Al 2 Si 3 O 12 , or two or more kinds thereof. 
     
     
         10 . The manufacturing method of  claim 4 , wherein an annealing temperature of the step of high temperature annealing the steel sheet to which the annealing separator is coated to obtain the primary film on the surface of the steel sheet is from 950 to 1250° C. 
     
     
         11 . The manufacturing method of  claim 4 , wherein the step of high temperature annealing the steel sheet to which the annealing separator is coated to obtain the primary film on the surface of the steel sheet includes:
 a step of increasing a temperature at an average of 50° C./h to 650° C. for the steel sheet coated with the annealing separator; and   a step of increasing a temperature at an average of 15° C./h from 650° C. to the annealing temperature in a mixed gas atmosphere of hydrogen and nitrogen.   
     
     
         12 . The manufacturing method of  claim 4 , wherein the step of decarburizing and nitriding-annealing the cold-rolled sheet is performed at 800 to 950° C. 
     
     
         13 . The manufacturing method of  claim 4 , wherein the steel slab includes 2.0 to 4.0 wt % of silicon (Si), 0.01 to 0.20 wt % of chromium (Cr), 0.02 to 0.04 wt % of aluminum (Al), 0.01 to 0.20 wt % of manganese (Mn), 0.04 to 0.07 wt % of carbon (C), 0.001 to 0.005 wt % of sulfur (S), 0.001 to 0.01 wt % of nitrogen (N), and Fe and other inevitable impurities as the remainder.