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Substitution for a process that uses chromic acid



I am working with a company that sells fire detection systems. They use

chromic acid (Cr+6) to etch molybdenum pins.   The molybdenum pins are
flame sealed to glass wafers with exposed portions of the pins that have
oxidized.  Corporate would like them to eliminate the use of chromic
acid.  The process goes like this:
o  Descaling using 29% Ammonium Hydroxide
o  Removal of the oxide coating using a mixture of nitric, hydrochloric
and sulfuric acid (this process leaves black spots from the oxidation)
o  Black spot removal using mixture of sulfuric acid and chromic acid

Are you aware of a process that can be substituted that would eliminate
the chromic acid, but still remove the oxidation off the Mo pins?

Thank you, Cindy

--
Cindy McComas
Director

Minnesota Technical Assistance Program
University of Minnesota
612/624-4678, 800/247-0015
http://www.mntap.umn.edu

Helping Minnesota businesses maximize resource efficiency, prevent pollution and reduce costs.

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