Anodizing of A357 sample for metallograpy
Anodizing of A357 sample for metallograpy
(OP)
Hi all,
I tired to anodize an A357 sample for metallographic observation usng perpendicular polarized light. I used Barkers solution (195 ml H2O + 5 ml HBF4) at room tempearture with 20V supply using Al cathode for 80 sec. But I was not able to get any contrast between the grains. I also tried a wrought alloy and pure Al but failed to get ay contrast. The samples were mechanically polished before anodizing. I also checked whether the surface is anodized or not using a multimeter and there was no current across the samples.
Can any body help me in this regard.
Thanks
Kamran
I tired to anodize an A357 sample for metallographic observation usng perpendicular polarized light. I used Barkers solution (195 ml H2O + 5 ml HBF4) at room tempearture with 20V supply using Al cathode for 80 sec. But I was not able to get any contrast between the grains. I also tried a wrought alloy and pure Al but failed to get ay contrast. The samples were mechanically polished before anodizing. I also checked whether the surface is anodized or not using a multimeter and there was no current across the samples.
Can any body help me in this regard.
Thanks
Kamran





RE: Anodizing of A357 sample for metallograpy
Another option Vander Voort presents is 100 ml H20, 4g KMnO4 and 1 g NaOH [Weck's reagent for Al]. Whether this will work on your grade of aluminum is unknown. Let me know.
I've used 10% Molybdic acid on pure aluminum, but had difficulty getting a decent photograph due to the fact that you've got to have almost 90° cross-polarized light, which didn't give me a lot of light to work with for the photograph.
RE: Anodizing of A357 sample for metallograpy
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