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Magnesium electropolishing and annealing
Hello,
I am studying the growth of fluoride and oxide films on magnesium and am having a few problems with surface preparation. I am using pure (99.9%) Mg foil and start the processing by cleaning and degreasing.
Two problems 1) Electropolishing seems to always leave the surface pits or undulations. I have tried several different recipes, and have had the best luck with ethanol saturated with sodium thiocyanide, electropolished at constant voltage (35V) and done at low temp (0 c). This is still not satisfactory, even by eye (I want a smooth mirror finish). I have good luck electropolish Al with a galvanostatic method, but cannot reproduce with Mg. Suggestions? 2) I would like to quantify the effects of annealing on the grain boundaries. I understand that one can make the boundaries visible via chemical etch but have had no luck finding specifics. Currently I am annealing under nitrogen/hydrogen at 350 c for around 1/2 hour.
Any Help is much appreciated!
Thank you,
Kevin Hobbs- Norman, Oklahoma
Hello again,
I suppose I am going to partially answer my own question here but I should report that I have improved on the electropolish situation by including a sulfuric acid pickle in my preclean. I am now able to get a mirror finish by eye, although some imperfections are still visible under the optical microscope. Suggestions are still welcome.
Thanks again,
Kevin Hobbs- Norman, Oklahoma
January 24, 2012
Hello Sir,
I am doing electropolishing of Mg alloys myself. May I ask you what temperature you use? I am using -45 to -55° Celsius myself, with 90V using a strueres Tenupul system.
Thank you
MSc. Fady Refaat Elsayed
PhD Student, Graduate School of Pure and Applied Science, University of Tsukuba
Research Assistant, Nano-Structure Analysis Group
Magnetic Materials Center
- Tsukuba, Japan