Alkaline zinc-iron plating bath

Abstract

The alkaline zinc-iron plating bath according to the present invention includes a zinc compound, an alkali hydroxide, a metal salt containing iron, and a complexing agent, in which the complexing agent is an aliphatic compound having five or more hydroxy groups. When the aliphatic compound having a chain structure and five or more hydroxy groups is used as the complexing agent, for example, due to an inhibitor effect thereof, redissolution of a deposited plating film is prevented; and as a result, a thick plating film can be efficiently formed.

1 . An alkaline zinc-iron plating bath comprising: a zinc compound, an alkali hydroxide, a metal salt containing iron, and a complexing agent, wherein the complexing agent is an aliphatic compound having five or more hydroxy groups. 
     
     
         2 . The alkaline zinc-iron plating bath according to  claim 1 , wherein the complexing agent is at least any one of sorbitol, xylitol, sodium gluconate, mannitol, glucose, fructose, lactose, and maltose. 
     
     
         3 . The alkaline zinc-iron plating bath according to  claim 1 , wherein 0.02 to 20 g/L of an iron ion is contained therein. 
     
     
         4 . The alkaline zinc-iron plating bath according to  claim 1 , wherein
 when 1.3 g/L or more of the iron ion is contained therein, a difference in the eutectic rates of iron in the current density of 0.5 to 10 ASD is 8% or less.   
     
     
         5 . The alkaline zinc-iron plating bath according to  claim 1 , wherein
 a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5.   
     
     
         6 . The alkaline zinc-iron plating bath according to  claim 2 , wherein 0.02 to 20 g/L of an iron ion is contained therein. 
     
     
         7 . The alkaline zinc-iron plating bath according to  claim 2 , wherein
 when 1.3 g/L or more of the iron ion is contained therein, a difference in the eutectic rates of iron in the current density of 0.5 to 10 ASD is 8% or less.   
     
     
         8 . The alkaline zinc-iron plating bath according to  claim 3 , wherein
 when 1.3 g/L or more of the iron ion is contained therein, a difference in the eutectic rates of iron in the current density of 0.5to 10 ASD is 8% or less.   
     
     
         9 . The alkaline zinc-iron plating bath according to  claim 6 , wherein
 when 1.3 g/L or more of the iron ion is contained therein, a difference in the eutectic rates of iron in the current density of 0.5 to 10 ASD is 8% or less.   
     
     
         10 . The alkaline zinc-iron plating bath according to  claim 2 , wherein
 a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5.   
     
     
         11 . The alkaline zinc-iron plating bath according to  claim 3 , wherein
 a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5.   
     
     
         12 . The alkaline zinc-iron plating bath according to  claim 6 , wherein
 a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5.   
     
     
         13 . The alkaline zinc-iron plating bath according to  claim 4 , wherein
 a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5.   
     
     
         14 . The alkaline zinc-iron plating bath according to  claim 7 , wherein
 a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5.   
     
     
         15 . The alkaline zinc-iron plating bath according to  claim 8 , wherein
 a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5.   
     
     
         16 . The alkaline zinc-iron plating bath according to  claim 9 , wherein
 a molar ratio of a metal containing zinc and iron to the complexing agent is 1:0.5 to 1:5.