Electroless process for treating metallic surfaces and products formed thereby

Abstract

The disclosure relates to a process for forming a deposit on the surface of a metallic or conductive surface. The process employs an electroless process to deposit a silicate containing coating or film upon a metallic or conductive surface.

1 . An electroless method for treating a substrate having an electrically conductive surface comprising: 
 contacting at least a portion of the surface with a medium comprising water, about 1 to about 15 weight percent of at least one silicate and having a basic pH and wherein said medium has a temperature of greater than about 50 C; and,    drying the substrate.    
     
     
         2 . The method of  claim 1  wherein the medium further comprises colloidal silica, and wherein the medium is substantially free of chromates and VOCs.  
     
     
         3 . An electroless method for treating a metallic or an electrically conductive surface comprising: 
 exposing at least a portion of the surface to a medium comprising a combination comprising water, colloidal silica, and at least one water soluble silicate wherein said medium has a basic pH,    drying the surface, ; and    contacting the treated surface with at least one composition that adheres to the treated surface.    
     
     
         4 . The method of  claim 3  wherein the colloidal silica has a particle size of less than about 50 nanometers.  
     
     
         5 . The method of  claim 1  wherein the surface comprises at least one member selected from the group consisting of copper, nickel, tin, iron, zinc, aluminum, magnesium, stainless steel and steel and alloys thereof.  
     
     
         6 . The method of  claim 1  further comprising rinsing after said drying and said rinsing comprises contacting the surface with a second medium comprising a combination comprising water and at least one water soluble compound selected from the group consisting of carbonates, chlorides, fluorides, nitrates, zironates, titanates, sulphates, water soluble lithium compounds and silanes.  
     
     
         7 . The method of  claim 1  wherein the medium comprises at least one dopant selected from the group consisting of zinc, cobalt, molybdenum, nickel, and aluminum.  
     
     
         8 . The method of  claim 1  wherein said drying is conducted at a temperature of at least about 120 C.  
     
     
         9 . The method of  claim 5  wherein said surface comprises zinc or zinc alloys.  
     
     
         10 . The method of  claim 7  wherein the medium comprises a combination comprising water, greater than about 1 weight percent of sodium silicate and at least one dopant selected from the group consisting of cobalt, nickel and molybdenum.  
     
     
         11 . The method of  claim 1  wherein the surface comprises a chromated surface.  
     
     
         12 . The method of  claim 3  wherein said medium further comprises at least one water dispersible polymer.  
     
     
         13 . The method of  claim 1  wherein said method further comprises contacting with at least one acid.  
     
     
         14 . The method of  claim 9  wherein said surface comprises zinc nickel alloys.  
     
     
         15 . The method of  claim 1  wherein the pH of the medium ranges from about 10 to about 12.  
     
     
         16 . The method of  claim 9  wherein the surface comprises die cast zinc.  
     
     
         17 . The method of  claim 1  wherein said medium further comprises at least one reducing agent selected from the group consisting of sodium borohydride and hypophosphide.  
     
     
         18 . The method of  claim 1  further comprising applying at least one coating selected from the group consisting of latex, silanes, epoxies, silicone, amines, alkyds, urethanes, polyester and acrylics.  
     
     
         19 . The method of  claim 1  wherein said at least one silicate comprises at least one alkali silicate having an alkali to silica ratio of about 1:3.