Overview - ISO 26424:2008 (abrasion resistance of ceramic coatings)
ISO 26424:2008 specifies a laboratory method to measure the abrasive wear rate of ceramic (fine/advanced) coatings using a micro-scale abrasion test based on the crater‑grinding technique (as used in ISO 26423). The test produces a spherical crater by rotating a hardened ball against the coated sample with an abrasive slurry fed into the contact zone. Results can quantify coating and substrate wear rates from single or multiple craters. The standard covers test apparatus, sample preparation, slurry and ball selection, measurement techniques and result analysis for flat samples; non‑planar samples require more advanced analysis or numerical methods.
Key topics and technical requirements
- Test principle: rotating ball pressed against sample while abrasive slurry produces a crater; crater dimensions are measured to determine wear rates.
- Scope limits: analysis in Clause 9 applies only to flat, homogeneous single‑layer coatings. Coating thickness must be > 1 µm.
- Apparatus:
- Typical test ball: 25 mm hardened steel (e.g., SAE 52100) conforming to ISO 3290‑1; conditioning (≈300 revolutions, multiple orientations) is recommended.
- Two system variants: free‑ball and fixed‑ball configurations; rotational speed stability and low run‑out are required.
- Abrasive slurry:
- Common media: silicon carbide (SiC) F1200 or fine alumina; particle size preferably ≤ ~5 µm.
- Recommended concentrations: dilute (≈2% vol) to promote grooving wear; concentrated (≈20% vol) to promote rolling wear. Slurry homogeneity must be maintained.
- Corrosion inhibitor (e.g., NaNO2) may be recommended for steel substrates.
- Measurement:
- Crater dimensions by calibrated optical microscopy, profilometry or calibrated image capture; measurement traceability to national standards is required.
- Note: different measurement methods (optical vs profilometry) can yield different crater sizes; do not compare results across methods without care.
- Data analysis: procedures for Type A (no perforation) and Type B (perforation) tests are defined to calculate abrasive wear coefficients for coating and substrate.
Applications and who uses it
- Materials engineers, tribologists and R&D teams testing advanced ceramic coatings for wear resistance.
- Coating manufacturers and quality control labs using the method for product verification or comparative screening.
- Test laboratories operating to ISO/IEC 17025 seeking standardized micro‑scale abrasion data for thin films, hard coatings, or small test pieces.
- Designers and specifiers selecting protective coatings for abrasion‑critical applications (cutting tools, wear parts, protective layers).
Related standards
- ISO 26423 - coating thickness determination (crater‑grinding technique basis)
- ISO 3290‑1 - rolling bearings - steel balls (ball specification)
- ISO/IEC 17025 - competence of testing and calibration laboratories
Keywords: ISO 26424:2008, fine ceramics, abrasion resistance, micro‑scale abrasion test, crater‑grinding, ceramic coatings, abrasive wear rate, coating wear testing.
Open preview (PDF)Fine ceramics (advanced ceramics, advanced technical ceramics) — Determination of the abrasion resistance of coatings by a micro-scale abrasion test