Metal treatment – Process of modifying or maintaining internal physical... – Producing or treating layered – bonded – welded – or...
Patent
1993-03-16
1995-05-09
Niebling, John
Metal treatment
Process of modifying or maintaining internal physical...
Producing or treating layered, bonded, welded, or...
204227, 204243M, 204259, 204287, 204289, C25D 306, C25D 356, C25D 550
Patent
active
054136466
ABSTRACT:
A method for depositing chromium and iron metals on substrates is disclosed in which the chromium hardens when heated. The electrolytic plating bath preferably includes: (a) water soluble Cr(III) produced by reducing Cr(VI) with sufficient amounts of methanol or formic acid; (b) ammonium formate; (c) a sulfate catalyst, such as sodium sulfate; (d) an inorganic iron compound, such as iron sulfate; (e) sufficient amounts of boric acid to substantially saturate the bath; and (f) a sufficient amount of sulfuric acid to provide a bath pH of from about 1.0 to about 1.5. The heat-hardenable chromium deposit allows the plated substrate to be heat tempered after plating to provide a KHN of greater than about 1200. This eliminates the necessity of removing oxidation products from an unplated heated substrate. Moreover, the amount of toxic Cr(VI) present in the bath is greatly diminished, and is replaced with a Cr(III) species that is environmentally safer. Electrolytic plating baths of the present invention having ammonium formate and a total sulfate concentration of about 140 g/L to about 180 g/L produce chromium and iron metal deposits on substrates having thicknesses of up to about 160 .mu.m. Moreover, the iron content of the deposit can be varied over a range of from about 10% to about 90% by adjusting the sulfate-to-iron ratio in the plating bath.
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Dash John
DeHaven John
Blount, Inc.
Leader William T.
Niebling John
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