Steel sheet for cans and method for producing same

Abstract

A steel sheet for cans is provided. The steel sheet for cans includes, on a surface of a steel sheet, two or more coating layers and a chromium-containing layer stacked in this order from a steel sheet side. The chromium-containing layer has a plurality of core-shell particles, the core-shell particles are disposed on, of the coating layers, one layer adjacent to the chromium-containing layer, and each of the core-shell particles has a core of chromium metal or a chromium compound and a shell of chromium oxide covering the core.

1 . A steel sheet for cans comprising,
 on a surface of a steel sheet, two or more coating layers and a chromium-containing layer stacked in this order from a steel sheet side,   wherein the chromium-containing layer has a plurality of core-shell particles,   the plurality of core-shell particles are disposed on, of the two or more coating layers, one layer adjacent to the chromium-containing layer, and   each of the plurality of core-shell particles has a core of chromium metal or a chromium compound and a shell of chromium oxide covering the core.   
     
     
         2 . The steel sheet for cans according to  claim 1 , wherein the core is in non-contact with, of the two or more coating layers, one layer adjacent to the steel sheet. 
     
     
         3 . The steel sheet for cans according to  claim 1 , wherein chromium oxide is present between the core and, of the two or more coating layers, one layer adjacent to the steel sheet. 
     
     
         4 . The steel sheet for cans according to  claim 1 ,
 wherein, of the two or more coating layers, one layer adjacent to the steel sheet is a chromium metal layer, and   of the two or more coating layers, one layer adjacent to the chromium-containing layer is a metal layer or a metal oxide layer.   
     
     
         5 . The steel sheet for cans according to  claim 4 ,
 wherein, of the two or more coating layers, one layer adjacent to the chromium-containing layer is the metal oxide layer, and   the metal oxide layer is a chromium oxide layer.   
     
     
         6 . The steel sheet for cans according to  claim 1 , wherein the two or more coating layers are two layers. 
     
     
         7 . The steel sheet for cans according to  claim 1 , wherein the core is formed of the chromium metal. 
     
     
         8 . The steel sheet for cans according to  claim 1 , wherein a coating weight of chromium metal is 50 to 200 mg/m 2 . 
     
     
         9 . The steel sheet for cans according to  claim 1 ,
 wherein an area fraction of the plurality of core-shell particles is 10% or more, and   a number density of the plurality of core-shell particles is 1 particle/μm 2  or more.   
     
     
         10 . The steel sheet for cans according to  claim 1 ,
 wherein a grain size of the core is 10 to 500 nm, and   a thickness of the shell is ⅓ or less of the grain size of the core and is 0.5 to 10.0 nm.   
     
     
         11 . The steel sheet for cans according to  claim 1 , wherein an aspect ratio of each of the plurality of core-shell particles is 2.0 or less. 
     
     
         12 . The steel sheet for cans according to  claim 1 , wherein the core is a single crystal. 
     
     
         13 . The steel sheet for cans according to  claim 1 , wherein the shell is amorphous. 
     
     
         14 . A method of manufacturing the steel sheet for cans according to  claim 1 , the method comprising:
 subjecting a steel sheet to a primary cathodic electrolysis treatment, an anodic electrolysis treatment, a secondary cathodic electrolysis treatment, and a tertiary cathodic electrolysis treatment in this order with use of an aqueous solution containing a hexavalent chromium compound and a fluorine-containing compound,   wherein a current density of the secondary cathodic electrolysis treatment is 15 A/dm 2  or less, and an electric quantity density of the secondary cathodic electrolysis treatment is 5.0 C/dm 2  or less.