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Amélioration de la tenue à la corrosion atmosphérique de matériaux utilisés en connectique (nickel doré). Traitements de surface par implantations d'ions

Authors
Journal
Comptes Rendus de l Académie des Sciences - Series IIC - Chemistry
1387-1609
Publisher
Elsevier
Publication Date
Volume
3
Issue
5
Identifiers
DOI: 10.1016/s1387-1609(00)01139-7
Keywords
  • Corrosion Atmosphérique
  • Nickel
  • Laiton
  • Dépôt D'Or
  • Implantation
Disciplines
  • Chemistry

Abstract

Abstract Improvement of the atmospheric corrosion resistance of materials used in connectics. Surface treatments by ion implantation. Tests of corrosion of a material, constituted of brass covered with an electrochemical nickel coating (thickness ≈ 5 μm) and with a gold coating (thickness ≈ 0.4 μm or ≈ 1 μm), used in electrical contact applications, have been carried out in humid synthetic air with low contents of NO 2 (0.2 vpm), SO 2 (0.2 vpm) and Cl 2 (0.01 vpm). The results obtained show that the corrosion products are well localised on the surface. The aggregates formed are principally constituted of basic nitrate, sulphate and chloride of nickel and zinc. These studies showed that the corrosion of the material is due to the presence of porosities in the gold and nickel layers. X-ray analysis (SEM/EDS) revealed the presence of carbon in these porosities, probably related to the presence of organic compounds in the electrolytic coating baths. During the galvanic corrosion of nickel and zinc, the carbon is rejected to the periphery of the aggregates. The amount of carbon was determined by Van De Graaff analysis, by (d,p) nuclear reaction. Some treatments of the material by ion implantation (titanium or titanium and nitrogen or helium) have been realised in order to suppress the porosities of the gold layer. These treatments lead to a remarkable improvement of the corrosion resistance of the material. © 2000 Académie des sciences / Éditions scientifiques et médicales Elsevier SAS atmospheric corrosion / nickel / brass / gold coating / ion implantation

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