Process for providing a tortoise-shell chromatic effect to metallic substrates

Abstract

The present invention relates to a chemical process for providing a tortoise-shell chromatic effect to nickelated metallic substrates, which comprises heating the metallic substrate to 100-110 ° C. and subsequent buffering at a temperature of 40-110° C. with an oxidizing solution based on sodium thiosulfate, a reagent metal and an acidifying compound.

1 . A process for providing a tortoise-shell chromatic effect to substrates which comprises heating of the substrate to a suitable temperature for providing a chromatic effect and the application under heat on a portion of said substrate of an oxidizing solution comprising a thiosulfate, a reagent metal and an acidifying compound.  
     
     
         2 . The process according to  claim 1 , characterized in that said thiosulfate is sodium or potassium thiosulfate.  
     
     
         3 . The process according to  claim 1 , characterized in that said metal is selected from copper acetate, lead acetate or their mixtures.  
     
     
         4 . The process according to  claim 1 , characterized in that said acidifying compound is selected from potassium acid tartrate, citric acid, hypophosphorous acid, acetone, formic aldehyde, acetic aldehyde, oxalic acid, salicylic acid, acetic acid and their mixtures.  
     
     
         5 . The process according to  claim 1 , characterized in that said oxidizing solution is applied by buffering on said substrate.  
     
     
         6 . The process according to  claim 1 , wherein there is the direct development of a tortoise-shell chromatic effect by heating said metallic substrate to a temperature within the range of 100-110° C. and buffering at a temperature within the range of 40-110° C. with an oxidizing solution comprising  
       
         
           
                 
                 
                 
                 
               
                     
                     
                 
                     
                     
                 
                     
                   sodium thiosulfate 
                   220-240 
                   g/l 
                 
                     
                   copper acetate 
                   30-40 
                   g/l 
                 
                     
                   potassium acid tartrate 
                   30-40 
                   g/l 
                 
                     
                     
                 
                     
                     
                 
             
                
                
               
               
                
                
                
                
                
               
            
           
         
       
       until the chromatic effect is obtained.  
     
     
         7 . The process according to  claim 6 , characterized in that the buffering of the metallic substrate takes place at a temperature ranging from 60-80° C.  
     
     
         8 . The process according to  claim 1 , wherein a tortoise-shell chromatic effect is developed in two phases, said process comprising: 
 an application phase by buffering a solution comprising                                                    sodium thiosulfate   220-240   g/l         lead acetate   30-40   g/l         potassium acid tartrate   30-40   g/l                                               on a metallic substrate heated to a temperature ranging from 140-150° C. and    a second application phase of a second oxidizing solution on said substrate at a temperature ranging from 40-80° C.    
     
     
         9 . The process according to  claim 8 , characterized in that in said second phase, the application of the oxidizing solution takes place by buffering or by immersion of the metallic substrate.  
     
     
         10 . The process according to  claim 8 , characterized in that said second oxidizing solution is a solution of ammonium persulfate.  
     
     
         11 . The process according to  claim 1 , characterized in that said substrate comprises a metal coating.  
     
     
         12 . The process according to  claim 11 , characterized in that said coating metal is selected from nickel, nickel alloys, steels, nickelated steels, copper, super-alloys.  
     
     
         13 . The process according to  claim 1 , characterized in that said metallic substrate is an action body of a gun.