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  for Metal Finishing since 1989
  

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Surface Treatment

We have some problems with corrosion on acid proof stainless steel. Currently we are spraying with a aqueous solution that contains chloride- and fluoride-ions. Can someone propose a good way to coat or plate our steel so we can minimize the corrosion in spray nozzles and other parts in our system? Or can we switch to another metal/alloy?

Goran Frennesson
- Malm¿, Sweden

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1st of two simultaneous responses-- Goran:

Based on your application I suppose that you cannot coat with or even make your parts with plastic like teflon or similar, so, if they have to be metallic, Have you checked an alloy named Hastelloy? (it's very popular in USA I guess its produced by an american co. named Hayes). I understand they have some grades that can perform in fluoride and chloride environments.

If that's not enough I think that you better be prepared to spend a lot in plating with noble metals. Fluoride and chloride ions together are the Nemesis in corrosion engineering.

Guillermo Marrufo
Monterrey, NL, Mexico
 

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2nd of two simultaneous responses--  

With chloride/fluoride mixed you are going to have problems with metals.

Could plastic be used? - Try asking for the best plastic quoting temperature, pressure, and solution.

Martin Trigg-Hogarth
surface treatment shop - Stroud, Glos, England