Overview
ISO 14676:1997 specifies a laboratory method - the wet‑peel test by the floating‑roller (mobile-roller) method - for evaluating the quality of surface treatment of aluminium and its alloys for high‑strength adhesive bonding. The procedure is intended to be a rapid, sensitive screening test that distinguishes adequately prepared surfaces (complete anodizing processes) from incomplete or inadequate pre‑treatments.
Key practical points from the standard:
- Applicable to aluminium and aluminium alloys used with high‑strength adhesives.
- Designed primarily for laboratory evaluation and screening rather than as a long‑term durability predictor.
- The wetting action of water with a surfactant reveals differences in failure mode and reductions in peel resistance for incompletely treated surfaces.
Key Topics
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Test principle: Use of the floating‑roller peel method to measure peel strength under dry and wet conditions. Application of a small quantity of water containing a wetting agent converts many cohesive failures to quasi‑adhesive failures where incomplete surface treatment exists.
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Typical test sequence: prepare and condition specimens per the standard; perform an initial dry peel at a controlled separation speed (100 ± 5 mm/min); stop after about 75 mm; apply approximately 1 ml (± 0.5 ml) of water containing a wetting agent (typically 0.5–1 % detergent) to the fracture area; resume peel immediately and record force versus displacement to completion.
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Data and reporting: record force–displacement curves and determine average peel force (kN/m) for both dry and wet regions over at least 55 mm. Exclude the first and last 20 mm of the recording and the first 10 mm of the wet region when calculating the average. Report mean, maximum and minimum forces and the observed failure modes.
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Limitations: the test is sensitive for differentiating pre‑treatments (for example, full chromic acid anodizing (CAA) or phosphoric acid anodizing (PAA) versus incomplete processes) but is not intended as a direct predictor of long‑term durability. Interlaboratory precision data were not available at publication.
Applications
- Quality control of aluminium surface pre‑treatments prior to structural adhesive bonding.
- Screening of pretreatment processes in R&D and production to detect incomplete or inadequate anodizing or cleaning steps.
- Comparative assessment of surface preparation methods when selecting pretreatment routes for bonded aluminium assemblies.
Related Standards
- ISO 4578 - mobile-roller peel method apparatus and general peel procedures.
- ISO 4588 - guide for surface preparation of metals.
- ISO 9142 - conditioning and laboratory ageing atmospheres.
- ISO 10365 - designation of failure modes (faciès de rupture).
Keywords: adhesives, wet-peel test, floating-roller, aluminium surface treatment, CAA, PAA, peel strength, laboratory evaluation.
Open preview (PDF)Adhesives — Evaluation of the effectiveness of surface treatment techniques for aluminium — Wet-peel test by floating-roller method