Thursday, June 23, 2005

ELECTROPOLISHING

Electropolishing is a procedure that is used to level out the surface of the aluminum template. By smoothening the surface, it will ensure that the pores form in the desired ordered, uniform array. The electropolishing of the aluminum metal involves two basic steps. The first is to prepare a solution of perchloric acid and ethanol (Pure perchloric acid would ruin the metal). I poured the solution into a 50 mL beaker, and then placed it in the center of a copper bowl. The second step is to place the dry ice around the beaker. Once I had put the dry ice around the beaker, I added acetone, which reacts with the dry ice to lower the temperature. Once the temperature drops to around -50 degrees Celsius, we can begin the procedure. The beaker should be pre-prepared with a stainless steel plate attached to save time. Otherwise, make sure it is set up before pouring the acid in the beaker. The stainless steel plate will be the cathode so I attached it to the appropriate wire on the voltmeter. The aluminum piece that is set to be electropolished will then be the anode, and should be lowered into the perchloric acid-ethanol solution once it is attached to the appropriate wire. The picture below provides a good visual of this setup. After setting the voltage to 20 volts, we just wait for 10 minutes to take out the polished, flattened aluminum piece now ready for anodization.

4 Comments:

Blogger Jean-Claude Bradley said...

I don't think the freezing point of dry ice will be changed by acetone but you do need the acetone to complete the bath - why?

8:09 AM  
Blogger brockbron said...

Interesting blog about dry acid, keep up the good work dry acid

11:06 AM  
Blogger xanthus said...

This comment has been removed by a blog administrator.

6:30 AM  
Blogger shima said...

what voltage and time used for electropolishing HSLA steel

12:56 PM  

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