Overview
ISO 24284:2022 specifies a laboratory corrosion test method for decorative chrome plating exposed to de-icing salt conditions (notably calcium chloride). The standard reproduces the special winter corrosion that occurs when hygroscopic, high‑salt mud and de-icing agents remain on chromium electroplated finishes (commonly nickel‑chromium or copper‑nickel‑chromium multilayer systems). It defines the apparatus, reagents and step‑by‑step procedure to assess corrosion resistance of exterior parts such as automotive trim and other decorative plated components.
Key topics and requirements
- Apparatus: humidity chamber with heating, specimen supports and air circulation; chamber must maintain 60 °C ± 3 °C and 30 % ± 5 % RH and prevent condensate dripping onto specimens.
- Test slurry (paste):
- Prepare a saturated calcium chloride (CaCl2·2H2O) solution at ~40 °C (example: >175 g in 100 ml water).
- Collect supernatant and mix with kaolin at a ratio of 5 ml concentrated CaCl2 solution : 3 g kaolin to yield a thick slurry with pH 3.0–4.0.
- Recommended storage of CaCl2 solution: up to one week in airtight container.
- Specimen preparation and application:
- Clean with acetone/alcohol; mark three circles (18 mm diameter / ~254 mm² each) on flat areas.
- Deposit 0.12–0.15 g slurry per circle, spread evenly, then place specimens horizontally in the chamber.
- Test conditions: exposure period is agreed between requester and laboratory (not fixed in the standard). After exposure, remove slurry under running water and dry.
- Evaluation & reporting:
- Typical inspection under 10× magnification; evaluation criteria specified in product/coating specifications (Annex B gives an example rating).
- Test report should include plating type and layer thicknesses, specimen count, cleaning and post-test methods, chamber conditions, exposure period and 10× photographs.
Applications and users
- Practical for automotive OEMs, plating shops, material laboratories and quality/validation engineers assessing decorative chrome parts for winter road exposure.
- Useful in product development, supplier qualification and failure analysis where de‑icing salt corrosion (especially CaCl2-related yellowing and chromium dissolution) must be reproduced and quantified.
- Complements general salt spray tests (ISO 9227) by simulating hygroscopic de‑icing mud effects not covered by standard salt spray methods.
Related standards
Keywords: ISO 24284:2022, de-icing salt, decorative chrome plating, calcium chloride, corrosion test, nickel-chromium, humidity chamber, slurry, automotive exterior parts.
Open preview (PDF)Metallic coatings — Corrosion test method for decorative chrome plating under a de-icing salt environment