molybdenum and fuming nitric acid

no idea... maybe the people from sci.chem could help you here.

Steve:
Bruce Craig's "Handbook of Corrosion Data" (ASM International 1989) says on page 378 that: "molybdenum is rapidly attacked by oxidizing agents such as nitric acid".
L. L. Shreir's "Corrosion" (2nd ed., Butterworths,1976), says that (P 5.15): "Molybdenum exhibits good reisistance to hydrochloric, hydrofluoric, phosphoric, and sulfuric acids....It is rapidly attacked by oxidizing acids such as nitric acid, and by reducing acids containing oxidizers such as HNO3, FeCl3, etc."
Similar information can be turned up via a Google search too of course.
Why are you using nitric acid?
Pittsburgh Pete
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Pete,
Thanks for that - The acid was being used to see if my material was pure - I am not a chemist, I am the engineer who designed the apparatus. It was my supposedly expert customer who suggested nitric as a kind of assay, since he didn't believe the metal was pure.
Steve