Process for treating a conductive surface and products formed thereby
View Patent ↗The disclosure relates to a process for forming a deposit on the surface of a metallic or conductive surface. The process employs an electrolytic process to deposit a silicate containing coating or film upon a metallic or conductive surface.
1. A method for treating a substrate having an electrically conductive surface comprising:
contacting at least a portion of the surface with a medium comprising at least one silicate and at least one member selected from the group consisting of at least one transition metal salt, sodium citrate and ammonium citrate, and having a basic pH and wherein said medium is substantially free of chromates and a temperature of greater than about 25 C. and less than about 95 C.,
introducing a current to said medium wherein said surface is employed as a cathode;
drying the substrate,
rinsing the substrate,
drying the substrate.
2. An aqueous medium for use in electrically treating a conductive surface comprising a combination comprising at least one polar carrier, at least one silicate soluble within said carrier, colloidal silica, at least one dopant and wherein the medium has a basic pH and is substantially free of chromates.
3. A 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 at least one polar carrier and at least one silicate that is soluble within said carrier wherein said medium has a basic pH nd a temperature of at least about 55 C.,
introducing an energy source into said first medium thereby treating the surface;
drying the surface at a temperature of at least about 75 C.,
rinsing the surface,
drying the surface; and
contacting the treated surface with at least one composition that adheres to the treated surface.
4. The method of claim 1 wherein the silicate containing medium comprises sodium silicate and colloidal silica.
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 wherein further comprising a post-treatment comprising 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, zirconates, titanates, sulphates, water soluble lithium compounds and silanes.
7. The method of claim 1 wherein the medium further comprises at least one dopant selected from the group consisting of zinc, cobalt, molybdenum and nickel.
8. The method of claim 1 wherein said first drying is conducted at a temperature of at least about 120 C.
9. The method of claim 1 further comprising applying at least one coating upon the post-treated surface.
10. The medium of claim 2 wherein the medium comprises greater than 1 wt. % of at least one silicate and further comprises at least one dopant selected from the group consisting of cobalt, nickel, molybdenum and zinc.
11. The method of claim 1 further comprising forming a layer comprising silica.
12. The medium of claim 2 wherein said medium further comprises at least one water soluble compound comprises at least one member selected from the group consisting of from the group of titanium chloride, tin chloride, zirconium acetate, zirconium oxychloride, calcium fluoride, tin fluoride, titanium fluoride, zirconium fluoride; ammonium fluorosilicate, aluminum nitrate; magnesium sulphate, sodium sulphate, zinc sulphate, copper sulphate; lithium acetate, lithium bicarbonate, lithium citrate, lithium metaborate, lithium vanadate and lithium tungstate.
13. The method of claim 1 wherein said anode comprises platinum or nickel.
14. The method of claim 1 wherein said rinsing comprising contacting said surface with a solution comprising water and at least one dopant.
15. The method of claim 14 wherein the dopant comprises at least one member selected from the group consisting of molybdenum, chromium, titanium, zircon, vanadium, phosphorus, aluminum, iron, boron, bismuth, gallium, tellurium, germanium, antimony, niobium, magnesium, manganese, zinc, aluminum, cobalt, nickel and their oxides and salts.
16. The method of claim 3 further comprising prior to said exposing contacting said surface with at least one member selected from the group consisting of acid and basic cleaners.
17. The method of claim 1 further comprising at least one dopant wherein the dopant is provided by the anode of the electrolytic environment.
18. The method of claim 3 wherein said adherent composition comprises at least one member chosen from the group of latex, silanes, epoxies, silicone, amines, alkyds, urethanes, polyester and acrylics.
19. An article comprising a zinc surface with a silicate containing inorganic film upon the surface and at least one coating adhered to the film wherein the article is chromate free and wherein article said has an ASTM B117 exposure to white rust of greater than 72 hours.