Method for ceramization of aluminum alloy surface

Abstract

The present invention provides a method for ceramization of an aluminum alloy surface, comprising the steps of: (1) providing a clean aluminum alloy surface; (2) pre-polishing; (3) etching; (4) polishing; and (5) performing ceramic oxidation. The advantages of the method are as follows: (1) good corrosion resistance, good elasticity and insulation; (2) the coating being similar to plastic, with enamel-like luster and attractive appearance; and (3) good adsorption capacity, capability of being dyed with different colors, and good decorative effect etc.

The invention claimed is: 
     
         1 . A method for ceramization of an aluminum alloy surface, comprising the steps of:
 ( 1 ) providing a clean aluminum alloy surface;   ( 2 ) pre-polishing: rinsing the aluminum alloy surface obtained in step  1  in concentrated nitric acid for 1-5 minutes, followed by washing, the concentrated nitric acid being 380-400 g/L;   ( 3 ) etching: rinsing the aluminum alloy surface obtained in step  2  in an etching solution for 1-5 minutes, followed by washing, the etching solution containing 45-50 g/L of sodium hydroxide and 45-50 g/L of sodium fluoride, and the temperature being 60-70° C.;   ( 4 ) polishing: rinsing the aluminum alloy surface obtained in step  3  in concentrated nitric acid for 1-5 minutes, followed by washing, the concentrated nitric acid being 380-400 g/L; and   ( 5 ) performing ceramic oxidation: electroplating the aluminum alloy surface in a ceramic oxidation solution for 45-48 minutes, followed by washing, the aluminum alloy surface being an anode, a current density of the anode being 0.5-1.0 A/dm 2 , a voltage being 28-38V and a temperature being 45-50° C., and the ceramic oxidation solution comprising 36-38 g/L of chromic anhydride and 6-11 g/L of oxalic acid.   
     
     
         2 . The method for ceramization of an aluminum alloy surface according to  claim 1 , wherein in step  1 , the clean aluminum alloy surface is obtained by the following method:
 ( 1 A) rinsing with an alkaline solution without sodium hydroxide at 25-35° C. for 15-20 minutes, and   ( 1 B) hot water washing followed by cold water washing.   
     
     
         3 . The method for ceramization of an aluminum alloy surface according to  claim 1 , wherein in step  2 , the aluminum alloy surface obtained in step  1  is rinsed in concentrated nitric acid for 4 minutes, and then washed, the concentrated nitric acid is 390 g/L. 
     
     
         4 . The method for ceramization of an aluminum alloy surface according to  claim 1 , wherein in step  3 , the aluminum alloy surface obtained in step  2  is rinsed in an etching solution for 4 minutes, and then washed, the etching solution contains 47 g/L of sodium hydroxide and 47 g/L of sodium fluoride, and the temperature is 65° C. 
     
     
         5 . The method for ceramization of an aluminum alloy surface according to  claim 1 , wherein after step  3 , hot water washing is followed by cold water washing; the hot water washing is performed 1-5 minutes, and a water temperature is 60-80° C.; the cold water washing is performed 1-5 minutes, and a water temperature is 15-20° C. 
     
     
         6 . The method for ceramization of an aluminum alloy surface according to  claim 1 , wherein in step  4 , the aluminum alloy surface obtained in step  3  is rinsed in concentrated nitric acid for 4 minutes, and then washed, the concentrated nitric acid is 390 g/L. 
     
     
         7 . The method for ceramization of an aluminum alloy surface according to  claim 1 , further comprising a step of rinsing the aluminum alloy surface under a high pressure water gun between steps  4  and  5 , a water pressure of the high pressure water gun is 1200-1400 Bar and a rinsing time is 30-60 seconds. 
     
     
         8 . The method for ceramization of an aluminum alloy surface according to  claim 1 , wherein in step  5 , the aluminum alloy surface is electroplated in a ceramic oxidation solution for 46 minutes, and then washed and dyed, the aluminum alloy surface is an anode, a current density of the anode is 0.72 A/dm 2 , a voltage is 32V and a temperature is 47° C. 
     
     
         9 . The method for ceramization of an aluminum alloy surface according to  claim 1 , further comprising step  6  of dyeing the aluminum alloy surface obtained in step  5  with a dye after step  5 . 
     
     
         10 . The method for ceramization of an aluminum alloy surface according to  claim 9 , wherein the step of dyeing is selected from the group consisting of:
 ( 6 A) dyeing at 25-35° C. for 6-8 minutes using a blue dyeing solution containing 12-48 g/L of potassium ferrocyanide and 25-80 g/L of potassium chloride;   ( 6 B) dyeing at 20-25° C. for 6-8 minutes using a black dyeing solution containing 55-85 g/L of cobalt acetate and 20-25 g/L of potassium permanganate; and   ( 6 C) dyeing at 25-35° C. for 6-8 minutes using a white dyeing solution containing 10-50 g/L of lead acetate and 20-40 g/L of sodium sulfate.