How is aluminium anodised?

Question

i am conducting a reasherch task for college and we need to know the process of how aluminium is anodised

Answer 1

The Main Rawmaterial for Aluminium is Bauxite where it is dissolved in NaoH solution after crushing and milling of Bauxite and allow to settle to sepearate the bottom where Alumina is settled down and it is sent for Electrolysis Process where DC current is used thru carbon Electrodes made up of Petoleum pitch and Coal tar pitch paste and Shell of Electrolysis chamber act as Cathode and Carbon electrodes are act as Anodes and baking is Done and Aluminium gets deposited at the bottom of Cathode chamber and will be removed peridically and These Carbon electrode needs to be coated with paste before using it

Answer 2

Like the word says, depositing a protective oxide film on aluminium by electrochemical oxidation (using it as the anode).

I hope your college wants a lot more detail than that.  Look up "anodizing" (use that American-style spelling) in Wikipedia and you will find more info and useful links.

Answer 3

Clean the aluminium to totally degrease it (caustic soda)

It will fizz for a while.

wash off.

Connect part to be anodized to positive voltage ("anodized" see?) and a lead cathode to negative. dip it in sulphuric acid solution. This opens up little pores in the surface of the metal.

After a bit more fizzing (about half an hour) take out the part and dip in dye which fills tiny holes in the surface.(this stage is optional you can leave it natural )

Dip the part in boiling water which seals the holes.

Wash the acid off in between etc and be carefull!

Job Done.

Answer 4

In the most basic of terms, you put it in a solution of the stuff you want it covered in. An electrical charge is then applied to the metal and the solution, so that the stuff you want it covered in comes out of the solution and goes onto the metal. I understand that the college might want a little bit more detail.