ISO/CD 21746 standard procedures of galvanic corrosion test for CFRP-metal assemblies

What is it about?

The authors have been proposing a new draft of standard test `ISO/CD 21746 composites and metal assemblies - galvanic corrosion tests ’that has approved through the committee draft (CD) vote under `Technical Committee ISO/TC 61, Plastics - Subcommittee SC 13, Composites and reinforcement fibres. ’ The authors have evaluated the procedures through a series of galvanic corrosion tests for CFRP-Al bolted assemblies of Toray T800S/3900-2B and Al 1050P in direct contact with conductive bolts, of insulative lm interface with conductive bolts and of insulative film interface with insulative bolts. The results were affirmative for the CD 21746 in the excellence for evaluating the galvanic corrosion, in the user-friendly descriptions and of low cost in the test chamber evaluation with newly dened pure Al reference specimens.

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Why is it important?

Galvanic corrosion in CFRP-metal assemblies is a newly arising hazard of aerospace structures in expanding CFRP applications. Wide gap of galvanic potentials between metallic materials and CFRPs form electro-chemical reaction cell to trigger severe corrosion, therefore the evaluation procedures have been needed for the protection methods such as calking, inhibitor painting and water sealant. However, present procedures such as ISO 9227 are intended for isolated samples, thus, galvanic paired samples of CFRP-metal assemblies are out of the scope.

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