Overview - EN ISO 26443:2023 (Rockwell indentation test for adhesion)
EN ISO 26443:2023 specifies a qualitative method to evaluate the adhesion of ceramic coatings (fine/advanced ceramics) up to 20 µm thick using a Rockwell diamond indenter. Indentations are made with a Rockwell hardness test instrument and the damaged area around the indent is inspected optically for adhesive or cohesive failure. The method can also be applied to some metallic coatings but is not suitable for elastic coatings on hard substrates.
Key topics and technical requirements
- Scope and principle
- Qualitative adhesion evaluation by Rockwell indentation and optical examination of cracks, flaking or delamination.
- Apparatus and standards referenced
- Indentations performed in accordance with ISO 6508-1 (test method) and machine/indenter verification per ISO 6508-2.
- Regular optical inspection of the diamond indenter (recommended magnification ≥×200).
- Load selection (based on substrate)
- Metallic substrates > 54 HRC: 1 471.5 N (Rockwell C scale).
- Metallic substrates ≤ 54 HRC and medium case‑hardened steel: 981 N (Rockwell D scale).
- Other substrates (thin substrates, cemented carbides, ceramics, cermets): 588.6 N (Rockwell A scale).
- Specimen preparation and procedure
- Clean, plane-parallel specimens; indent perpendicular to surface.
- Optical examination (recommended ×100) and classification against the standard’s table (Classes 0–3).
- At least three representative indents recommended.
- Result classification
- Class 0: No cracking or adhesive delamination (acceptable).
- Class 1: Cracking without adhesive delamination (acceptable).
- Class 2: Partial adhesive delamination (unacceptable) - estimate percent delaminated area.
- Class 3: Complete adhesive delamination (unacceptable) - report r/a ratio.
- Reporting and limits
- Report equipment, calibration, sample description, load used, number/location of indents, and observed class.
- Compare results only for similar coating/substrate combinations, thicknesses and identical test loads.
Applications - who uses it and why
- Coating engineers and materials scientists evaluating adhesion of ceramic or metallic coatings on ceramics, metals, cermets and carbides.
- Quality control laboratories verifying production coatings (thin ceramic layers ≤ 20 µm).
- R&D teams screening coating/substrate combinations for adhesion performance.
- Useful for failure analysis where cohesive cracking or adhesive delamination after mechanical loading is suspected.
Related standards
- ISO 6508-1: Rockwell hardness test - test method
- ISO 6508-2: Rockwell hardness test - verification and calibration of machines and indenters
- EN ISO 26443:2023 replaces EN ISO 26443:2016
Keywords: EN ISO 26443:2023, Rockwell indentation test, adhesion of ceramic coatings, fine ceramics, ceramic coating adhesion test, Rockwell diamond indenter.
