Corrosion-resistant alloy coating film for metal materials and method for forming same

Abstract

A method for producing an iron base material having a coating includes forming a Ni—Cr—Si corrosion-resistant alloy coating film by a combination of composite plate processing with a Ni solution containing Cr and Si, and a heat treatment after the composite plate processing, wherein the Ni—Cr—Si corrosion-resistant film contains Ni, Cr, and Si, and wherein a content ratio of Cr is 1 to 50 wt % of the alloy coating film, a content ratio of Si is 0.1 to 30 wt % of the alloy coating film, and the alloy coating film has a thickness of 0.1 to 1000 μm, the composite plate processing forms a composite plating film, in which a chromium silicide particle selected from Cr 3 Si, Cr 5 Si 3 , Cr 3 Si 2 , CrSi and CrSi 2 is co-deposited in a Ni matrix, and the heat treatment at 600° C. or higher decomposes and solid-solubilizes 50% or more of the chromium silicide particle in the Ni matrix.

What is claimed is: 
     
         1 . A method for producing an iron base material having a coating, comprising:
 forming a Ni—Cr—Si corrosion-resistant alloy coating film by a combination of composite plate processing with a Ni solution containing Cr and Si, and a heat treatment after the composite plate processing,   wherein the Ni—Cr—Si corrosion-resistant alloy coating film contains Ni, Cr, and Si as essential constituents, and wherein a content ratio of Cr is 1 to 50 wt % based on a total weight of the alloy coating film, a content ratio of Si is 0.1 to 30 wt % based on the total weight of the alloy coating film, and the alloy coating film has a thickness of 0.1 to 1000 μm,   the composite plate processing is a process of forming a composite plating film, in which at least one chromium silicide particle selected from the group consisting of Cr 3 Si, Cr 5 Si 3 , Cr 3 Si 2 , CrSi and CrSi 2  is co-deposited in a Ni matrix, and   in the heat treatment, the composite plating film is heated at a temperature of 600° C. or higher to decompose and solid-solubilize 50% or more of the chromium silicide particle co-deposited in the Ni matrix.   
     
     
         2 . The method according to  claim 1 , wherein an inter-diffusion layer of 50 nm or more in thickness containing Ni, Cr and Fe is formed as a portion of the Ni—Cr—Si corrosion-resistant alloy coating film at an interface between the iron base material and the alloy coating film. 
     
     
         3 . The method according to  claim 1 , wherein the composite plate processing is a method selected from the group consisting of electroplate processing using a direct-current power supply, PR plate processing using a pulsed power supply, and electroless plate processing using a reductant. 
     
     
         4 . The method according to  claim 2 , wherein the composite plate processing is a method selected from the group consisting of electroplate processing using a direct-current power supply, PR plate processing using a pulsed power supply, and electroless plate processing using a reductant. 
     
     
         5 . The method according to  claim 1 , wherein in the Ni solution for the composite plating processing, a supply source of Cr and Si is at least one chromium silicide particle selected from the group consisting of Cr 3 Si, Cr 5 Si 3 , Cr 3 Si 2 , CrSi and CrSi 2 , and the chromium silicide particle is a particle having 100 μm or less in a longer diameter. 
     
     
         6 . The method according to  claim 2 , wherein in the Ni solution for the composite plating processing, a supply source of Cr and Si is at least one chromium silicide particle selected from the group consisting of Cr 3 Si, Cr 5 Si 3 , Cr 3 Si 2 , CrSi and CrSi 2 , and the chromium silicide particle is a particle having 100 μm or less in a longer diameter. 
     
     
         7 . The method according to  claim 3 , wherein in the Ni solution for the composite plating processing, a supply source of Cr and Si is at least one chromium silicide particle selected from the group consisting of Cr 3 Si, Cr 5 Si 3 , Cr 3 Si 2 , CrSi and CrSi 2 , and the chromium silicide particle is a particle having 100 μm or less in a longer diameter. 
     
     
         8 . The method according to  claim 5 , wherein the processing solution contains the chromium silicide particle within a range of 10 to 2000 g/L in the Ni solution. 
     
     
         9 . The method according to  claim 6 , wherein the processing solution contains the chromium silicide particle within a range of 10 to 2000 g/L in the Ni solution.