Acid dip for zinc-manganese alloy electrodeposition
AssigneeCoventya, Inc.
InventorsLionel Thiery, Gianluigi Schiavon, Nicolas Pommier
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Abstract
The invention relates to a dip comprising an acid aqueous solution having no ammonium ion, fluoroborate ions or citrate ion and containing per liter: between 10 and 60 g of Zn2+ ions and between 20 and 100 g of Mn2+ ions. The invention is characterised in that it comprises a buffer agent that maintains the pH at a value of between 3 and 7, preferably between 4.5 and 6 or better still between 4.8 and 5.5, and another agent, different from the buffer agent, which is used to bring together the deposition potentials of couple Zn/Zn2+ and couple Mn/Mn2+. The inventive dip used to deposit a Zn and Mn alloy by electrolysis.
Claims12
An acidic aqueous solution devoid of ammonium ion, of fluoroborate ion and of citrate ion and comprising, per liter,
- from 10 to 60 g of Zn2+ ions,
- from 20 to 100 g of Mn2+ ions,
- a buffering agent, and
- an agent for bringing closer the potentials for deposition of a Zn/Zn2+ couple and of a Mn/Mn2+ couple that is a compound of formula
- R1—(CH2—CH2—O)n—R2
- 0<n<25
- wherein R1=aryloxy group, aryloxyalkoxy group, alkylaryl group, alkylaryloxy group, or alkylaryloxyalkoxy group,
- R2=-H, —(CH2)m−SO3−M+, where m =0 to 5, —(CH2)2—PO32−M+2, -where z =0 to 2, or —CH2—COO−M+, where M+=Na+, K+or NH4+or aryl, present in a concentration of 0.5 to 15 g/l.
Dependencies are inferred from the claim text.