Metal finishing Q&As since 1989
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Pitting on nickel plated steel parts when immersed in sulfuric and ammonium bifluride etch
Hello my name is Emily Gardiner. I work for an Aerospace Company in The South East of England. We are Currently experiencing problems with patches of pitting and sometimes reddish marks when anodic etching nickel plated steel parts in a sulfuric Acid and Ammonium Bifluoride Etch solution. Ideas I have had that may be causing the issue are perhaps too much Ammonium bifluoride, contaminants in the etching bath, or contaminants in the Nickel Plate.I am very keen to hear from those who have similar problems and ways in which you went about solving the issue or indeed anyone with some bright ideas. Thanks for your time guys!
Emily GardinerChemist - London, England
July 24, 2008
What are your coating specifications and processes?
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
July 28, 2008
Sorry for late response! Holiday season! Just to let you know we have resolved the issue. The problem was on reworked parts where patches of 'old' nickel were present. Due to insufficient cleaning, these areas, when immersed in etch solution were etching at a much more aggressive and faster rate thus causing the patches of pitting.
Thanks for your interest.
Aerospace - London, England
August 13, 2008
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