Metal finishing Q&As since 1989

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Non-corrosive coating for severe environment (LiCl and water)

We want to develop a boiler for aqueous LiCl solution, which is very corrosive. Solution concentration is about 44%, boiling temperature is about 300 F, and lifetime should be on the order of 20,000 hours, with temperature cycling every few hours. We know that Titanium, Monel and Inconel 600 are suitable materials, but these are expensive.

Is there any way to make the parts out of cheaper metals (e.g., steel, SS, Al, Cu, etc.), then finish these metals with a suitably non-corrosive coating? What kind of finishes should we consider?

Tom Tonon
- Princeton Junction, New Jersey
2001

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How large is this vessel? Is the inside of the vessel accessible?

Both nickel and silver are highly resistant to strong alkaline solutions--perhaps a thick silver plate would do the trick. Maybe even a precious metal plating. If you want to get exotic, most refractory oxides (zirconium, hafnium) are practically insoluble in alkalies but to coat a large vessel it is going to be challenging.

[If this is a small to moderately sized item--contact us!]

You are approaching the upper temperature limit of PTFE, but it is possible a teflon bag insert could be used in you vessel. As long as there is no movement or stress put on the teflon, you may be ok.

Dale Woika
Surface Conversion Sciences - Bellefonte, Pennsylvania, USA
2001