Process for surface treating aluminum and aluminum alloy articles

Abstract

A process for surface treating aluminum and aluminum alloy articles is provided. The method includes the steps of providing a substrate of aluminum or aluminum alloy material, the substrate having an internal surface and an external surface; machining the external surface of substrate, thereby forming a first surface appearance on the external surface; forming a first oxide coating with a first color on the substrate surface by a first anodizing process; removing at least a portion of the first oxide coating on the internal surface of the substrate to make the substrate electricity conductive; machining the external surface of the substrate, thereby removing at least a portion of the first oxide coating on the external surface and forming a second surface appearance thereon; forming a second oxide coating with a second color on the area of the external surface excluding the first oxide coating by a second anodizing process.

1 . A process for surface treating aluminum and aluminum alloy articles comprising:
 providing a substrate, the substrate being made of aluminum or aluminum alloy material, the substrate having an internal surface and an external surface;   machining the external surface of the substrate, thereby forming a first surface appearance on the external surface;   forming a first oxide coating on the whole substrate surface by a first anodizing process;   dyeing a first color on the first oxide coating;   removing at least a portion of the first oxide coating on the internal surface to make the substrate electrically conductive;   machining the external surface of the substrate, thereby removing at least a portion of the first oxide coating on the external surface and forming a second surface appearance thereon;   forming a second oxide coating on the area of the external surface excluding the first oxide coating by a second anodizing process; and   dyeing a second color on the second oxide coating.   
     
     
         2 . The process for surface treating aluminum and aluminum alloy articles as claimed in  claim 1 , wherein the first surface appearance is a dull surface appearance formed by sandblasting. 
     
     
         3 . The process for surface treating aluminum and aluminum alloy articles as claimed in  claim 2 , wherein the second surface appearance is a texture of line strips. 
     
     
         4 . The process for surface treating aluminum and aluminum alloy articles as claimed in  claim 1 , wherein the first and second anodizing process are carried out in a electrolytic bath containing about 180-220 g/L sulfuric acid at a temperature of about 19-21° C. 
     
     
         5 . The process for surface treating aluminum and aluminum alloy articles as claimed in  claim 4 , wherein a direct current out in an approximate range from about 10 to 12 volts is used for about 45 to 55 minutes in the first anodizing process. 
     
     
         6 . The process for surface treating aluminum and aluminum alloy articles as claimed in  claim 5 , wherein a direct current in an approximate range from about 9.5 to 10.5 volts is used for about 28 to 32 minutes in the second anodizing process. 
     
     
         7 . The process for surface treating aluminum and aluminum alloy articles as claimed in  claim 1 , wherein a portion or all of the first oxide coating is removed form the internal surface of the substrate by a laser carving process. 
     
     
         8 . The process for surface treating aluminum and aluminum alloy articles as claimed in  claim 1 , further comprising a sealing process after the first and the second anodizing process. 
     
     
         9 . The process for surface treating aluminum and aluminum alloy articles as claimed in  claim 1 , wherein the dyeing process is an adsorption staining process. 
     
     
         10 . The process for surface treating aluminum and aluminum alloy articles as claimed in  claim 1 , further comprising before the first anodizing process, pre-treating the substrate by degreasing the surface of the substrate, chemically polishing the surface of the substrate and then removing the black coating on the substrate surface formed in the chemically polishing procedure. 
     
     
         11 . A process for surface treating aluminum and aluminum alloy articles comprising:
 providing a substrate, the substrate being made of aluminum or aluminum alloy material, the substrate having an internal surface and an external surface, the external surface having a first surface appearance thereon;   forming a first oxide coating on the substrate surface by a first anodizing process;   dyeing a first color on the first oxide coating;   machining the external surface of the substrate, thereby removing at least a portion of the oxide coating on the external surface and forming a second surface appearance thereon;   forming a second oxide coating on the area of the external surface excluding the first oxide coating by a second anodizing process; and   dyeing a second color on the second oxide coating.   
     
     
         12 . The process for surface treating aluminum and aluminum alloy articles as claimed in  claim 11 , wherein the first surface appearance is formed by a first machining process. 
     
     
         13 . The process for surface treating aluminum and aluminum alloy articles as claimed in  claim 12 , wherein the first surface appearance is a dull surface appearance formed by sandblasting. 
     
     
         14 . The process for surface treating aluminum and aluminum alloy articles as claimed in  claim 13 , wherein the second surface appearance is a texture of line strips. 
     
     
         15 . The process for surface treating aluminum and aluminum alloy articles as claimed in  claim 11 , further comprising covering at least portions of the internal surface before the first anodizing step. 
     
     
         16 . The process for surface treating aluminum and aluminum alloy articles as claimed in  claim 11 , wherein at least portions of the internal surface is covered by ink. 
     
     
         17 . The process for surface treating aluminum and aluminum alloy articles as claimed in  claim 11 , further comprising a sealing process after the first and the second anodizing steps.