Method for preparing and using silicate systems to treat electrically conductive surfaces and products obtained therefrom

Abstract

The disclosure relates to treating a silicate medium and using the treated medium for improving the surface of metallic or electrically conductive materials. The treated medium provides a silicate medium having a defined degree of polymerization and predetermined quantities of the desired silicate polymer. The treated silicate medium can be employed in an electroless or electrolytic process.

The following is claimed:  
     
         1 . A method for treating a substrate having an electrically conductive surface comprising: 
 preparing a medium comprising water and at least one silicate and wherein the medium has a basic pH,    passing a current through the medium and then;    contacting at least a portion of the surface with the medium.    
     
     
         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 . A method for treating a metallic or an electrically conductive surface comprising: 
 preparing a medium comprising water and at least one silicate and wherein the medium has a basic pH,    placing an anode and a cathode in electrical contact with the medium,    exposing at least a portion of the surface to a medium,    passing a current through the medium wherein the surface is not in direct contact with the anode or cathode.    
     
     
         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 drying and rinsing 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 6  wherein said drying is conducted at a temperature of at least about 120C.  
     
     
         9 . The method of  claim 5  wherein said surface comprises zinc or zinc alloys.  
     
     
         10 . The method of  claim 1  wherein said surface comprises a chromated surface.  
     
     
         11 . The method of  claim 3  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  further comprising pretreating the surface prior to said contacting.  
     
     
         16 . 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.  
     
     
         17 . The method of  claim 15  wherein the pretreating comprises contacting the surface with at least one member selected from the group consisting of sodium acetate, aluminum ammonium sulfate, aluminum phosphate, aluminum nitrate, aluminum fluoride, aluminum potassium sulfate, aluminum tartate, sodium ammonium phosphate and sodium gluconate.