Composite material, method for producing the composite material, and terminal

Abstract

There is provided a composite material in which a composite coating composed of a silver layer containing carbon particles is provided on a base material, the composite coating having a silver crystallite size of more than 40 nm and not more than 70 nm and having an arithmetic mean roughness Ra (μm) of 2.0 μm or less.

1 . A composite material in which a composite coating composed of a silver layer containing carbon particles is provided on a base material, the composite coating having a silver crystallite size of more than 40 nm and not more than 70 nm and having an arithmetic mean roughness Ra (μm) of 2.0 μm or less. 
     
     
         2 . The composite material according to  claim 1 , wherein the base material is composed of Cu or a Cu alloy. 
     
     
         3 . The composite material according to  claim 1 , wherein a surface of the composite coating has a Vickers hardness of 90 or more. 
     
     
         4 . The composite material according to  claim 1 , wherein the composite coating has a silver crystallite size of 50 to 66 nm. 
     
     
         5 . The composite material according to  claim 1 , wherein an underlayer composed of at least one selected from the group consisting of Cu, Ni, Sn, and Ag is provided between the base material and the composite coating. 
     
     
         6 . A method for producing a composite material, the method comprising: forming a composite coating composed of a silver layer containing carbon particles on a base material by performing electroplating in a silver plating solution containing the carbon particles and containing a compound A represented by the following general formula (I), 
       
         
           
           
               
               
           
         
         (In general formula (I), m is an integer from 1 to 5; 
         Ra is a carboxyl group; 
         Rb is an aldehyde group, a carboxyl group, an amino group, a hydroxyl group, or a sulfonic acid group; 
         Rc is hydrogen or an arbitrary substituent; 
         when m is 2 or more, a plurality of Rb's may be the same or different; 
         when m is 3 or less, a plurality of Rc's may be the same or different; and 
         Ra and Rb may each independently be bonded to a benzene ring via a divalent group composed of at least one selected from the group consisting of —O— and —CH 2 —), 
         wherein pulse plating is performed as the electroplating. 
       
     
     
         7 . The method for producing a composite material according to  claim 6 ,
 wherein during the pulse plating, alternate repeat is performed to a composite coating deposition of depositing silver on the base material to form a silver matrix containing the carbon particles and a composite coating dissolution of dissolving a part of the silver matrix of the composite coating, and the following conditions are adopted for this pulse plating,   the composite film deposition: applying a current at a current density of 1.5 to 5.0 A/dm 2 ;   the composite coating dissolution: applying a current at a current density of −12 to −2.5 A/dm 2 ;   wherein alternate repeat count of the composite coating deposition and the composite coating dissolution is 300 to 10,000 times, and   a ratio (Tp/Td) is 2 to 8, which is the ratio of time period Tp for applying a current in the composite coating deposition with respect to time period Td for applying a current in the composite coating dissolution.   
     
     
         8 . The method for producing a composite material according to  claim 6 , wherein a concentration of the carbon particles in the silver plating solution is 10 g/L or more and 150 g/L or less. 
     
     
         9 . A terminal for electrical contacts, the terminal comprising the composite material according to  claim 1  as a constituent material. 
     
     
         10 . The composite material according to  claim 2 , wherein a surface of the composite coating has a Vickers hardness of 90 or more. 
     
     
         11 . The composite material according to  claim 2 , wherein the composite coating has a silver crystallite size of 50 to 66 nm. 
     
     
         12 . The composite material according to  claim 2 , wherein an underlayer composed of at least one selected from the group consisting of Cu, Ni, Sn, and Ag is provided between the base material and the composite coating. 
     
     
         13 . The method for producing a composite material according to  claim 7 , wherein a concentration of the carbon particles in the silver plating solution is 10 g/L or more and 150 g/L or less. 
     
     
         14 . A terminal for electrical contacts, the terminal comprising the composite material according to  claim 2  as a constituent material.