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Remove Cr/Au from stainless steel

2002

I need a solution for quickly removing Cr/Au thin films from stainless steel tooling. The tooling is used as shutters, fixtures and structures inside of an ebeam vacuum chamber. The chamber is used heavily and thus if not maintained regularly can get fairly thick buildups. KI and aqua regia damage stainless. Is there a reasonably simple solution?

John O'Kelly
- Seattle, Washington

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2002 A. Hydrochloric acid (reasonably simple I think) dissolves chromium. Cyanide (reasonably simple you think?) dissolve gold. None attack SS. Guillermo Marrufo Monterrey, NL, Mexico 2002 A. Stripping pure Au is no problem -we currently do it in a proprietary bath from local vendor(containing cyanides), which works fast without damaging substrate. Pure Cr we normally strip in a diluted (10%) HCl. I would try or combine both ways. Frantisek Haas - Jablonec, Czech Republic

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2002

A. I agree with the responses above, except HCl will attack stainless steel. It needs to be soaked in NaOH or similar afterwards to remove residual chlorides that can attack the grain boundaries.

Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois