ISO 24284:2022

INTERNATIONAL ISO
STANDARD 24284
First edition
2022-01
Metallic coatings — Corrosion test
method for decorative chrome plating
under a de-icing salt environment
Revêtements métalliques — Méthode d'essai de corrosion pour le
chromage décoratif en présence de sels de déverglaçage
Reference number
© ISO 2022
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Apparatus . 1
5 Test slurry . 2
5.1 Preparation of the calcium chloride (CaCl ) solution . 2
5.2 Preparation of the slurry (paste) . 2
6 Procedure .2
7 E valuation of the results .3
8 Test report . 3
Annex A (informative) Graphical procedure of de-icing salt corrosion test .4
Annex B (informative) Example for rating after de-icing salt corrosion test .6
Bibliography . 7
iii
Foreword
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This document was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coatings,
Subcommittee SC 7, Corrosion tests.
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iv
Introduction
Decorative, electrodeposited nickel-chromium and copper-nickel-chromium coatings, built up with a
multilayer nickel system including micro-discontinuous nickel, are applied to manufactured articles to
enhance their appearance and corrosion resistance.
These coating systems are characterized by unique corrosion mechanisms. Once corrosion begins, the
nickel layer gets dissolved preferentially (especially in the case of a bright nickel layer): it acts as an
anode with respect to chromium (which is intended to act as a cathode). In addition, lots of tiny pores or
cracks in the micro-discontinuous layer distribute the corrosion current throughout the whole surface.
In this way the amount of current at a given corrosion site is substantially lowered, creating minor pits
that remain for a longer time invisible to the naked eye. In addition, the corrosion penetration through
the bright nickel layer is reduced, especially when a more noble semi-bright nickel layer shields it from
the substrate or the copper underlayer.
An additional different corrosion phenomenon is caused during winter by de-icing salts, especially
calcium chloride. This particular corrosion phenomenon is characterized by slightly yellow and less
shiny spots on the surface, caused by the complete dissolution of the chromium layer and the partial
deterioration of the microporous nickel layer. In this situation, the bright nickel layer remains intact.
Such corrosion phenomena are predominantly occurring in areas with cold winter conditions and the
use of calcium chloride as de-icing agent in combination with dirt dust deposits.
Unfortunately, this corrosion phenomenon cannot be tested and evaluated using existing corrosion test
methods [e.g. salt spray (see ISO 9227) and Corrodkote test].
v
INTERNATIONAL STANDARD ISO 24284:2022(E)
Metallic coatings — Corrosion test method for decorative
chrome plating under a de-icing salt environment
1 Scope
This document specifies the apparatus, reagents, and procedure to assess the corrosion resistance
of chromium electroplated parts in the presence of de-icing salts (especi
...