Protective coatings for metals

Abstract

Metal products having improved properties and processes for preparing the metal products are provided. In an embodiment, the present disclosure provides for a metal product comprising a metal surface, an oxide layer and a glass layer. The glass layer is provided by coating a stable aqueous silicate or borosilicate solution onto the metal surface and curing the aqueous solution to produce a glass layer. The metal products have surface characteristics that outperform current anodized metal surfaces.

1 . A metal product comprising:
 an oxide-glass layer carried by a surface of a metal;   the oxide-glass layer comprising a transitional interface layer disposed between a prepared oxide layer and a silicate glass layer; and   the prepared oxide layer adjacent and tightly adhered to the surface of the metal.   
     
     
         2 . The metal product of  claim 1 , wherein the metal is selected from the group consisting of Zn, Mn, Mg, Al, Ti, Fe, Cr, Ni, Pb, and alloys of those metals. 
     
     
         3 . The metal product of  claim 2 , wherein the metal is selected from the group consisting of Al, Ti, Cr, Mn, Ni and alloys of those metals. 
     
     
         4 . The metal product of  claim 3 , wherein the metal is aluminum or an aluminum alloy. 
     
     
         5 . The metal product of  claim 1 , wherein the oxide layer is an oxide of the metal. 
     
     
         6 . The metal product of  claim 5 , wherein the oxide layer is an anodization product of the metal. 
     
     
         7 . The metal product of  claim 1 , wherein the silicate glass layer is derived from the condensation polymerization of an alkali metal silicate selected from the group consisting of lithium silicate, sodium silicate, potassium silicate and combinations thereof. 
     
     
         8 . The metal product of  claim 7 , wherein the alkali metal silicate comprises a plurality of counter ions and the plurality of counter ions include at least about 10 atom % sodium. 
     
     
         9 . The metal product of  claim 1 , wherein the silicate glass layer is a borosilicate glass layer. 
     
     
         10 . The metal product of  claim 9 , wherein the borosilicate glass layer is derived from the condensation polymerization of an alkali metal silicate selected from the group consisting of lithium silicate, sodium silicate, potassium silicate and combinations thereof, and a borate. 
     
     
         11 . The metal product of  claim 10 , wherein the alkali metal silicate comprises a plurality of counter ions and the plurality of counter ions include at least about 10 atom % sodium. 
     
     
         12 . The metal product of  claim 1  further comprising a thickness of the oxide-glass layer in a range of about 0.1 microns to about 10 microns. 
     
     
         13 . The metal product of  claim 12 , wherein the thickness of the oxide-glass layer is in the range of 0.1 microns to about 5 microns. 
     
     
         14 . The metal product of  claim 13 , wherein the thickness of the oxide-glass layer is in the range of 0.1 microns to about 3 microns. 
     
     
         15 . The metal product of  claim 1 , wherein the oxide layer has a thickness of less than about 5 microns. 
     
     
         16 . The metal product of  claim 15 , wherein the oxide layer has a thickness in a range of about 50 nm to about 500 nm. 
     
     
         17 . The metal product of  claim 15 , wherein the oxide layer has a thickness in a range of about 1 micron to about 2 microns. 
     
     
         18 . A coated aluminum article comprising:
 an aluminum or aluminum alloy surface;   a prepared aluminum oxide layer tightly adhered to the aluminum or aluminum alloy surface; and   a borosilicate glass layer chemically bonded to the prepared aluminum oxide layer;   wherein the borosilicate glass layer is less than about 1000 nm thick.   
     
     
         19 . The coated aluminum article of  claim 18 , wherein the borosilicate glass is less than about 500 nm thick. 
     
     
         20 . The coated aluminum article of  claim 19 , wherein the borosilicate glass is less than about 250 nm thick. 
     
     
         21 . The coated aluminum article  claim 18  having a pencil hardness of greater than 6H. 
     
     
         22 . The coated aluminum article of  claim 18  having a salt spray corrosion resistance as measured by ASTM B-117-37 of greater than about 350 hours. 
     
     
         23 . A silicate glass coated aluminum coil comprising:
 an aluminum coil carrying an anodized aluminum oxide layer;   the anodized aluminum oxide layer carrying a silicate glass layer; and   an oxide-glass layer comprising the anodized aluminum oxide layer and the silicate glass layer and having a thickness in a range of about 0.1 microns to about 10 microns.   
     
     
         24 . A reflective article comprising:
 a transparent coating on a metal sheet;   the transparent coating comprising an oxide-glass layer;   the underlying, metal sheet having a reflectance; and   a photometric total reflectance through the transparent coating of greater than 75%.   
     
     
         25 . The reflective article of  claim 24 , wherein the total reflectance is greater than about 85%.