Hexavalent chromium-free hard coat maskant

Abstract

A part including corrosion- and wear-resistant regions has a base alloy with a plurality of surfaces, a corrosion-resistant coating deposited on at least one surface, and a wear-resistant coating deposited on at least one surface. The corrosion-resistant coating includes a thin film sulfuric acid anodize sealed with sequentially applied dipotassium hexafluorozirconate, lanthanum nitrate hexahydrate plus hydrogen peroxide, and hydrothermal seal systems. The wear-resistant coating comprises hardcoat anodize.

1 . A part including corrosion- and wear-resistant regions comprising:
 a base alloy with a plurality of surfaces;   a corrosion-resistant coating deposited on at least one surface, wherein the corrosion-resistant coating comprises:
 a thin film sulfuric acid anodize sealed with sequentially applied dipotassium hexafluorozirconate, lanthanum nitrate hexahydrate plus hydrogen peroxide, and hydrothermal seal systems; and 
   a wear-resistant coating deposited on at least one surface, wherein the wear-resistant coating comprises hardcoat anodize.   
     
     
         2 . The part of  claim 1 , wherein the base alloy is aluminum or an aluminum alloy. 
     
     
         3 . The part of  claim 2 , wherein the base alloy is an aluminum alloy selected from the group consisting of 2000 series, 6000 series, and 7000 series aluminum alloys. 
     
     
         4 . The part of  claim 1 , wherein the thin film sulfuric acid anodize comprises aluminum oxide coating between 0.00254 mm to 0.0254 mm (0.0001 in to 0.001 in) thick. 
     
     
         5 . The part of  claim 1 , wherein the hardcoat anodize comprises aluminum oxide coating between 0.0127 mm to 0.0762 mm (0.0005 inches to 0.0030 inches) thick. 
     
     
         6 . The part of  claim 1 , wherein the corrosion-resistant coating and wear-resistant coating are substantially hexavalent chromium free with a chromium (VI) oxide concentration of below 0.1 wt %. 
     
     
         7 . The part of  claim 1 , wherein the corrosion-resistant coating comprises residual lanthanides. 
     
     
         8 . The part of  claim 1 , wherein:
 the base alloy is an aluminum alloy selected from the group consisting of 2000 series, 6000 series, and 7000 series aluminum alloys;   the thin film sulfuric acid anodize comprises aluminum oxide coating between 0.00254 mm to 0.0254 mm (0.0001 in to 0.001 in) thick;   the hardcoat anodize comprises aluminum oxide coating between 0.0127 mm to 0.0762 mm (0.0005 inches to 0.0030 inches) thick;   the corrosion-resistant coating and wear-resistant coating are substantially hexavalent chromium free with a chromium (VI) oxide concentration of below 0.1 wt %; and   the corrosion-resistant coating comprises residual lanthanides.   
     
     
         9 . A method for forming corrosion- and wear-resistant regions on a part, the method comprising:
 providing the part with a plurality of surfaces, wherein the part comprises a base alloy;   degreasing the part;   deoxidizing the degreased part;   applying a thin film sulfuric acid (TFSA) anodize to the deoxidized part;   sealing the TFSA anodized part with an aqueous solution of dipotassium hexafluorozirconate;   sealing the TFSA anodized part with an aqueous solution of lanthanum nitrate hexahydrate plus hydrogen peroxide;   sealing the TFSA anodized part with a hydrothermal seal, wherein the combination of TFSA anodize, dipotassium hexafluorozirconate seal, lanthanum nitrate hexahydrate seal, and hydrothermal seal form corrosion-resistant regions on the part;   machining the combination of TFSA anodize, dipotassium hexafluorozirconate seal, lanthanum nitrate hexahydrate seal, and hydrothermal seal from regions of the part to receive a wear-resistant treatment to expose base alloy; and   applying hardcoat anodize to base alloy in regions of the part to receive a wear-resistant treatment, thereby forming the wear-resistant treatment.   
     
     
         10 . The method of  claim 9 , further comprising rinsing the part with water after each of the degreasing step, the deoxidizing step, the TFSA anodize step, the dipotassium hexafluorozirconate sealing step, and the lanthanum nitrate hexahydrate sealing step. 
     
     
         11 . The method of  claim 9 , further comprising inspecting the corrosion-resistant region for hardcoat breakthrough following the hardcoat anodize step. 
     
     
         12 . The method of  claim 9 , wherein the aqueous solution of dipotassium hexafluorozirconate comprises between >=1% and <3% dipotassium hexafluorozirconate. 
     
     
         13 . The method of  claim 9 , wherein the aqueous solution of lanthanum nitrate hexahydrate comprises between >=1% and <3% lanthanum nitrate hexahydrate. 
     
     
         14 . The method of  claim 9 , wherein the base alloy is aluminum or an aluminum alloy. 
     
     
         15 . The method of  claim 14 , wherein the base alloy is an aluminum alloy selected from the group consisting of 2000 series, 6000 series, and 7000 series aluminum alloys. 
     
     
         16 . The method of  claim 9 , wherein the thin film sulfuric acid anodize comprises aluminum oxide coating between 0.00254 mm to 0.0254 mm (0.0001 in to 0.001 in) thick. 
     
     
         17 . The method of  claim 9 , wherein the hardcoat anodize comprises aluminum oxide coating between 0.0127 mm to 0.0762 mm (0.0005 inches to 0.0030 inches) thick. 
     
     
         18 . The method of  claim 9 , wherein the corrosion-resistant coating and wear-resistant coating are substantially hexavalent chromium free with a chromium (VI) oxide concentration of below 0.1 wt %. 
     
     
         19 . The method of  claim 9 , wherein the corrosion-resistant coating comprises residual lanthanides. 
     
     
         20 . The method of  claim 9 , wherein:
 the base alloy is an aluminum alloy selected from the group consisting of 2000 series, 6000 series, and 7000 series aluminum alloys;   the thin film sulfuric acid anodize comprises aluminum oxide coating between 0.00254 mm to 0.0254 mm (0.0001 in to 0.001 in) thick;   the hardcoat anodize comprises aluminum oxide coating between 0.0127 mm to 0.0762 mm (0.0005 inches to 0.0030 inches) thick;   the aqueous solution of dipotassium hexafluorozirconate comprises between >=1% and <3% dipotassium hexafluorozirconate;   the aqueous solution of lanthanum nitrate hexahydrate comprises between >=1% and <3% lanthanum nitrate hexahydrate;   the corrosion-resistant coating and wear-resistant coating are substantially hexavalent chromium free with a chromium (VI) oxide concentration of below 0.1 wt %; and   the corrosion-resistant coating comprises residual lanthanides.