Electro-polishing (EP) experiments are carried out on niobium samples at Saclay
in order to highlight the influence of parameters such as temperature and acids
concentrations (hydrofluoric and sulfuric). First results given at the 12th SRF Workshop
have been completed. The importance of the HF/H2O ratio has been precisely investigated
and diluted mixtures have been tested during long time experiments: removal rates,
surface states, lifetime of the bath and possible hydrogen contamination will be reported.
In addition, some experiments have been carried out with dissolved niobium in fresh mixtures,
giving some ideas about mechanisms involved in EP. Furthermore, dissolved salts as well as
different acids have been tried as an alternative for hydrofluoric acid use. |
