HiI have some ceramic beads which were used as electric insulaters inside a vacuum coater and as a result are coated by some metals like Ti,.!I used HCl 36% and dipped them for a few hours in it but nothing happaened! any idea?!
Naturally, the reagents required will depend on what metal(s) are in the deposits. If the metal is titanium, as you suggest, then it will take something like a nitric-hydrofluoric acid mixture to do the job. Generally, the mixture would be on the order of concentrated nitric acid 2 parts, hydrofluoric acid 1 part, and water 1 part by volume. NOTE: Although nitric acid has its hazards, the hydrofluoric acid is an especially dangerous and insidious material. It causes severe burns that are not immediately painful and may not be apparent until hours later when it's too late to do much good for them. If you have it available, ammonium bifluoride is a somewhat safer and equally effective alternative to the hydrofluoric acid. Whatever you use, be sure you understand the dangers and use appropriate safety gear. Of course, there's the possibility that the fluorides will also etch your ceramics - it depends on what they are. Good luck with this project. Be sure to try small test samples before going large-scale.
Removal of the film depends upon what metal it is. Different metals dissolve in different reagents.
