Pickling solution
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The components of the passivation solution are nitric acid and hydrofluoric acid; does the concentration of anion ions in the solution after passivation and pickling change? Can a sufficient concentration of passivation solution be obtained by adding a sufficient concentration of hydrogen ions?
Seems to be the case, but I still feel that something’s off about that place.
Passivation generally refers to the phenomenon in which, when a metal comes into contact with a strongly oxidizing acid, an oxide layer with corrosion-resistant properties forms on the metal surface. The main factor that causes metal passivation is acids with strong oxidizing properties, not merely a high concentration of hydrogen ions; this is because the hydrogen ion concentration in some acids that lack oxidizing properties can still be high, such as hydrochloric acid. During the passivation process, the concentration of oxidizing anions changes, as does the concentration of hydrogen ions. As time goes by with the use of this acid, the passivation solution loses its ability to effect passivation.