Aluminum alloy part and associated manufacturing method

Abstract

A part including an aluminum alloy body, —a first layer that contains aluminum oxide and is arranged on the body, —an intermediate layer containing chromium, and—a second layer containing aluminum oxide, the intermediate layer being arranged between the first layer and the second layer.

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         5 . A method of manufacturing a part comprising the following chronological steps of:
 (a) supplying an aluminium alloy body,   (d) anodically oxidizing the body,   (e) impregnating the body with an impregnating solution comprising a trivalent chromium salt and an oxidising compound, and   (f) sealing the body with a sealing solution comprising an aluminate.   
     
     
         6 . The method according to  claim 5 , wherein the sealing solution has a mass concentration of aluminate of between 0.1 g/L and 10 g/L, preferably between 0.5 g/L and 5 g/L. 
     
     
         7 . The method according to  claim 5 , wherein the aluminate is a sodium aluminate. 
     
     
         8 . The method according to  claim 5 , wherein in step (d), the body is immersed in a tank comprising a sulphuric anodic oxidation solution comprising sulphuric acid in a mass concentration of between 150 g/L and 250 g/L, preferably 180 g/L. 
     
     
         9 . The method according to  claim 5 , wherein the impregnating solution has a temperature of between 30° C. and 50° C., preferably 40° C. 
     
     
         10 . The method according to  claim 5 , further comprising, between steps (e) and (f), a step (e′) of post-impregnating the body with a post-impregnating solution comprising hydrogen peroxide and a lanthanum salt. 
     
     
         11 . The method according to  claim 5 , wherein the oxidizing compound is a hexafluorozirconate salt. 
     
     
         12 . The method according to  claim 5 , wherein the sealing solution has a pH of between 7 and 12, preferably 11.