Surface-treated steel sheet

Abstract

A surface-treated steel sheet includes a steel sheet; and a plating layer which is formed on one surface or both surfaces of the steel sheet and which includes zinc and one of the group consisting of vanadium and zirconium, wherein the plating layer includes dendrite-shaped crystals including metallic zinc, and intercrystal filling regions which fill spaces between the dendrite-shaped crystals and show amorphous diffraction patterns when electron beam diffraction is carried out, wherein when the plating layer includes the vanadium, the intercrystal filling regions include a hydrated vanadium oxide or a vanadium hydroxide, and, wherein when the plating layer includes zirconium, the intercrystal filling regions include a hydrated zirconium oxide or a zirconium hydroxide.

1 - 9 . (canceled) 
     
     
         10 . A surface-treated steel sheet comprising:
 a steel sheet; and   a plating layer which is formed on one surface or both surfaces of the steel sheet and which includes zinc and one of the group consisting of vanadium and zirconium,   wherein the plating layer includes   dendrite-shaped crystals including metallic zinc, and   intercrystal filling regions which fill spaces between the dendrite-shaped crystals and show amorphous diffraction patterns when electron beam diffraction is carried out,   wherein when the plating layer includes the vanadium, the intercrystal filling regions include a hydrated vanadium oxide or a vanadium hydroxide, and   wherein when the plating layer includes zirconium, the intercrystal filling regions include a hydrated zirconium oxide or a zirconium hydroxide.   
     
     
         11 . The surface-treated steel sheet according to  claim 10 , further comprising:
 a base-material layer made of crystals including nickel between the steel sheet and the plating layer.   
     
     
         12 . The surface-treated steel sheet according to  claim 10 ,
 wherein, when the plating layer includes the vanadium, V/Zn which is a molar ratio of the vanadium to the zinc in the intercrystal filling regions is 0.10 or more and 2.00 or less, and   wherein when the plating layer includes the zirconium, Zr/Zn which is a molar ratio of the zirconium to the zinc in the intercrystal filling regions is 1.00 or more and 3.00 or less.   
     
     
         13 . The surface-treated steel sheet according to  claim 10 ,
 wherein the plating layer includes the vanadium, and   surface layers of the dendrite-shaped crystals include a zinc oxide or a zinc hydroxide.   
     
     
         14 . The surface-treated steel sheet according to  claim 10 , further comprising:
 a base-material plating layer having Zn/V, which is a molar ratio of zinc to vanadium, of 8.00 or more between the steel sheet and the plating layer.   
     
     
         15 . The surface-treated steel sheet according to  claim 11 , further comprising:
 a base-material plating layer having Zn/V, which is a molar ratio of zinc to vanadium, of 8.00 or more between the base-material layer and the plating layer.   
     
     
         16 . The surface-treated steel sheet according to  claim 10 , further comprising:
 an organic resin film having a polyurethane resin and 1% to 20% by mass of carbon black on a surface of the plating layer.   
     
     
         17 . A method for manufacturing the surface-treated steel sheet according to  claim 10 , the method comprising:
 a base-material-forming process of forming protrusions and recesses by precipitating a hydrated vanadium oxide or a vanadium hydroxide on the steel sheet in a case in which a plating layer comprises vanadium, or by precipitating a hydrated zirconium oxide or a zirconium hydroxide on the steel sheet in a case in which a plating layer comprises zirconium, by carrying out an electroplating at an average flow rate of 40 to 200 m/min and a current density of 0 to 18 A/dm 2  using a plating bath containing 0.10 to 4.00 mol/l of Zn 2+  ions and one of the group consisting of 0.01 to 2.00 mol/l of V ions and 0.10 to 4.00 mol/l of Zr ions; and   an upper layer plating process of carrying out an electroplating on the steel sheet on which the protrusions and the recesses are formed at an average flow rate of 40 to 200 m/min and a current density of 21 to 200 A/dm 2  using the plating bath.   
     
     
         18 . The method for manufacturing a surface-treated steel sheet according to  claim 17 , further comprising: before the base-material-forming process,
 a process of precipitating crystals including nickel on the steel sheet by carrying out an electroplating using a plating bath containing Ni 2+  ions.