I'm looking to electropolish magnesium alloys containing either aluminium or zinc (up to ~8 wt%). From the ASM possible solutions are 800ml ethanol &200ml HClO4, 625ml ethanol & 375ml H3PO4 or 900ml ethylene glycol monoethyl ether & 100ml HCl.
I've tried the H3PO4 electrolyte already, but there appears to be no difference in just immersing the sample and having the current on (2v). Both cases produce vigorous bubbling from the sample, with hydrogen evolution from the cathode as well when the current is on.
Basically, has anyone electropolished these alloys before? If so, what electrolyte, voltage and time did you find successfull?
-- Andrew Blake email@example.com