Theoretically, just adding the salt should work, but I doubt it is soluble in fuming nitric acid. The nitric acid would dissolve a bit of the metal,
but the fluoride in solution should immediately precipitate the dissolved metal ions making a passivating coating of metal fluoride.
If your application can tolerate 5% water in your nitric acid, then you might also consider using commercial 10% HF as an inhibitor. Some italian
stores sell it where I live as rust remover (it looks like this and a bottle costs 1 Euro https://goo.gl/images/Cj8fCL)
[Edited on 19-10-2018 by CobaltChloride] |