Overview
ISO 23114:2020 specifies a standardized laboratory method to determine the bonding strength of ceramic coatings (fine/advanced ceramics) at ambient temperature. The method uses compression tests on a specially prepared cross-joined test piece to produce either tensile or shear stresses at the coating–substrate interface. It applies to thin or thick ceramic coatings bonded to a variety of substrates and is intended for materials research, quality control, characterization and design-data generation.
Key topics and technical requirements
- Test principle: compressive loading of a cross-joined specimen to induce tensile or shear stresses at the interface; record failure load and calculate bonding strength from the joined area.
- Test pieces: preparation of a coating sample and a perpendicular coupling bar joined by high-strength adhesive to create the cross-joined test piece; storage and number of test pieces are specified.
- Fracture modes: interface debonding (true bonding strength), cohesive failure within the coating, and adhesive joint failure - single or mixed modes are possible and influence interpretation of results.
- Apparatus and metrology:
- Testing machine accuracy: in accordance with ISO 7500-1, Class 1 (1% load accuracy).
- Data acquisition: recording load vs. displacement/time; devices accurate to 1% with a minimum acquisition rate of 10 Hz (50 Hz recommended).
- Dimension measurement: micrometers or equivalent with resolution/accuracy of 0.01 mm (per ISO 3611).
- Fixtures: pressure head and sample holder geometry to avoid asymmetric stress; fixture material with elastic modulus > 200 GPa recommended.
- Test procedure and calculation: defined placement, cross-head rate, measurement of tensile/shear failure loads, evaluation of true debonded area, and calculation of tensile bonding strength and shear bonding strength.
- Reporting: procedures for data collection and reporting of failure loads, joined area, fracture mode and calculated strengths.
Practical applications
- Quality control and production acceptance testing of ceramic coatings (protective, thermal barrier, wear-resistant coatings).
- Research and development: compare coating processes, materials, surface treatments and adhesives.
- Materials characterization and design: provide input data for component design, simulation and lifetime assessments.
- Failure analysis: determine whether coating detachment is due to poor interface bonding, cohesive weakness, or adhesive joint failure.
Who should use this standard
- Materials scientists and R&D engineers working with advanced ceramic coatings
- Coating process engineers and QC laboratories
- Component designers and reliability engineers requiring bond-strength data
- Test laboratories performing interlaboratory comparisons and method validation
Related standards
- ISO 7500-1 - Calibration and verification of static uniaxial testing machines
- ISO 3611 - Micrometers for external measurements (dimensional metrology)
- Annex A of ISO 23114:2020 addresses interlaboratory testing guidance
Keywords: ISO 23114:2020, bonding strength, ceramic coatings, fine ceramics, tensile bonding strength, shear bonding strength, cross-joined test piece, test method, quality control, materials research.