Features observed during reanodizing in 0.1 M ammonium pentaborate electrolyte through the preformed barrier film formed in molten eutectic mixture of NaHSO
4:NH
4HSO
4 (1:1 mol), as a mobile tracer, results from the operation of several factors, such as film density, current density, and field strength. When the density of the preformed film is less than that of the second stage film, the preformed film is perfectly preserved and the incorporated sulphate ions in the preformed film are immobile under the influence of high field during reanodizing. Therefore, it is likely that the preformed film behaves as an ideal inert marker layer.
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