Silicate Coatings

Abstract

Metal products having improved properties and processes for preparing the metal products are provided. 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 all anodized metal surfaces.

What is claimed: 
     
         1 . A process for preparing a silicate surface coating comprising:
 forming a coated-aluminum-oxide layer by applying an aqueous silicate solution to an aluminum oxide layer that has a thickness of about 1 μm to about 25 μm,
 the aluminum oxide layer consisting of a sealed, anodized-aluminum layer or a hydrated PVD alumina layer and having an EDX composition that is free of silicon, boron and/or nickel, 
 the aqueous silicate solution having a pH of about 11 to about 13, a composition that includes a ratio of SiO 2  to M 2 O of about 3.5 to about 2, where M is selected from Li, Na, K, and a mixture thereof, and a ratio of SiO 2  to B 2 O 3  of about 10:1 to about 200:1; and thereafter, 
   polymerizing and curing a silicate glass on the sealed, anodized-aluminum layer by (A) heating the coated, anodized-aluminum layer to a temperature of about 200° C. to about 500° C. or (B) exposing the coated, anodized-aluminum layer to an infrared source.   
     
     
         2 . The process of  claim 1  further comprising:
 providing an aluminum surface; 
 anodizing the aluminum surface to provide an unsealed, anodized-aluminum layer; and then 
 hot sealing the unsealed aluminum oxide layer to provide the sealed, anodized-aluminum layer. 
 
     
     
         3 . The process of  claim 2  further comprising a hot sealing time of less than 6 min/micron. 
     
     
         4 . The process of  claim 3 , wherein the hot sealing time is less than 5 min/micron. 
     
     
         5 . The process of  claim 4 , wherein the hot sealing time is less than 2 min/micron. 
     
     
         6 . The process of  claim 5 , wherein the hot sealing time is less than 2 min/micron. 
     
     
         7 . The process of  claim 2  further comprising hot sealing the unsealed anodized-aluminum layer and the forming the coated, anodized-aluminum layer within less than 60 minutes. 
     
     
         8 . The process of  claim 7 , where the coated, anodized-aluminum layer is formed within less than 30 minutes of the hot sealing. 
     
     
         9 . The process of  claim 8 , where the coated, anodized-aluminum layer is formed within less than 10 minutes of the hot sealing. 
     
     
         10 . The process of  claim 2  further comprising holding the sealed, anodized-aluminum layer in a wet atmosphere, in water, or coated with water; and then forming the coated, anodized-aluminum layer by applying the aqueous silicate solution. 
     
     
         11 . A process for preparing a silicate surface coating comprising:
 hot sealing an anodized aluminum layer for less than 6 minutes/micron of a thickness of the anodized aluminum layer; then within 30 minutes of a completion of the hot sealing   immersing the hot sealed anodized aluminum layer in an aqueous silicate solution for about 5 minutes, the aqueous silicate solution having a pH of about 11 to about 13, a composition that includes a ratio of SiO 2  to M 2 O of about 3.5 to about 2, where M is selected from Li, Na, K, and a mixture thereof, and a ratio of SiO 2  to B 2 O 3  of about 10:1 to about 200:1; and then without rinsing,   polymerizing and curing the aqueous silicate solution coated, hot sealed anodized aluminum layer by (A) heating the coated, anodized-aluminum layer to a temperature of about 200° C. to about 500° C. and/or (B) exposing the coated, anodized-aluminum layer to an infrared source.   
     
     
         12 . The process of  claim 11 , wherein the hot sealed anodized aluminum layer has an EDX composition that is free of silicon, boron, and/or nickel. 
     
     
         13 . The process of  claim 11 , wherein the hot sealed anodized aluminum layer has an EDX composition that consists of aluminum, oxygen, sulfur, and an optional colorant. 
     
     
         14 . The process of  claim 11 , wherein the silicate surface coating includes an aluminum oxide layer having a composition that is free of silicates; and a silicate glass layer carried directly on the aluminum oxide layer and having a silicate glass layer EDX composition that consists of silicon, oxygen, sodium, optionally lithium, and optionally boron; wherein the silicate glass layer EDX composition is free of aluminum.