Study Of Improving Anti-corrosion Coating On The Surface Of Electric Heater Of 3003 Aluminum Alloy

3003 aluminum alloy can be used as an electric heater in air-conditioning.After a period of use in coastal or acid rain areas,the surface is corroded and a layer of white dust will be generated.white dust suffuses in house rooms when air conditioner runs.In this paper,the corrosion resistance of 3003 aluminum alloy can not meet the request,We use the surface modification technology of aluminum alloy to improve its corrosion resistance.They are anodic oxidation and electroless nickel,which are adapt to mass production.This paper researches the anodic oxidation of 3003 aluminum alloy,which was carried out by using serveral kinds of acid mixed electrolyte in constant current.Orthogonal experiments were carried out for it to determine the optimum anodic oxidation process parameters,which were as follows:sulfosalicylic acid 70g/L,boric acid 30g/L,oxalic acid 25g/L,current density 2.5A/dm².And under the optimum process parameters,the morphology,thickness,composition,structure and corrosion resistance of the oxide film were analyzed by SEM,EDS,electrochemical workstation and so on.The results show that the anodic oxidation can obviously improve the corrosion resistance.The results indicate that the hole diameter of the anodic oxidation film is small,less than 40 nm,and porosity is low,almost 16%,the thickness is 29μm.Anodic oxide film prepared under the optimum process has small self-corrosion current density 1.317×10^-7 A/cm²,which is 2 degrees smaller than normal anodic oxidation film’s.After anodizing,the sealing treatment will further improve the corrosion resistance.The self-corrosion current density of the nickel acetate sealing treatment is minimum.1.065×10^-7 A/cm²,which means minimum electrochemical corrosion rate.The results of electroless plating nickel and phosphorus plating for 3003aluminum alloy show that the same high quality electroless layers can be produced by replacing the tedious two zinc leaching process with simple electroless nickel plating activation process.The electroless plating nickel and phosphorus layers produced in the two different experiment methods have the same composition the percentage of phosphorus（weight percentage）,which are not crystallization state and whose self-corrosion current density is lower than the based material’s.The two electroless plating nickel and phosphorus layers can attain the effect of protecting the based material.When ultrasonic wave has been imported in electroless plating,The size of nickel phosphorus particles can be smaller than the normal electroless plating.When the ultrasonic power is 30W,the embossment cell of electroless plating layer is more uniformity and smaller than others’.