How To: Clean Molybdenum

Q: We have started to qualify Alconox Precision Cleaner for our clean line to clean parts for ultra high vacuum applications. Worked great on the stainless parts. But, when we tested an old molybdenum platen with a bead blasted metallic surface, it went black. Do you have a recommendation?

A: While metallic molybdenum is not generally reactive to water or alkaline solutions for the most part, it may be reacting with the phosphates in the Alconox® Powdered Precision Cleaner.

Molybdenum phosphates tend to be a really deep blue color, which could easily look black on the right surface.

To remove oxidation and other inorganics, and to safely clean reactive metals, we recommend Citranox® Liquid Acid Cleaner and Detergent. The mild organic acid detergent is going to work very well on metallic molybdenum, and we can even provide a source:

https://inis.iaea.org/collection/NCLCollectionStore/_Public/26/041/26041401.pdf

The paper also suggests using an alkaline cleaner first and then follow that up with Citranox detergent.

For low foaming applications such as using a washer or spray cabinet system, use Citrajet® Low-Foam Liquid Acid Cleaner/Rinse.