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Molten Fluoride Activation Bath

IP.com Disclosure Number: IPCOM000076773D
Original Publication Date: 1972-Apr-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Kannenberg, WG: AUTHOR [+2]

Abstract

Chromium oxide films on steels are readily removed in preparation for surface treatment of parts, such as case hardening, by immersion in a molten fluoride bath.

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Molten Fluoride Activation Bath

Chromium oxide films on steels are readily removed in preparation for surface treatment of parts, such as case hardening, by immersion in a molten fluoride bath.

A eutectic mixture of sodium and potassium fluorides has been found most convenient because of its low-melting point (700 degrees C), ready availability and good solubility in water. Other fluorides of Group I metals are effective and have Lower melting points, but are more expensive, toxic, and not readily available.

The bath is highly corrosive to pot materials in the presence of oxygen and must be maintained under a protective atmosphere such as forming gas or nitrogen. A protective atmosphere has the further advantage of permitting immersed parts to be withdrawn from the bath without reforming an oxide film. Adhering salt can be removed by immersion in a bath of alkaline cleaner and water at 190-200 degrees F.

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