Cathodic Protection Tests for the Galvanic Corrosion of Airframe Grade CFRP/Al Systems

Abstract

This paper reports on cathodic protection tests for airframe Alclad grade pure aluminum under galvanic corrosion risk by nobler carbon fiber reinforced plastics (CFRPs). Ti-bolt fastened aluminum Al-1050 and CFRP T800S/3900-2B (TORAY) has been subjected to salt water splay test to show that the sacrificial grids of AZ-31 and AZX612 protect the Al passivation layer, even though the difference in potential of anodic Al1050 and T800S/300-2B CFRPs, which contains cathodic graphite fibers, was found sufficient to trigger the galvanic corrosion. Even though electrical insulators, such as glass fiber reinforced plastics (GFRPs) and caulking resin layers, have been applied for the protection of galvanic corrosion, the impacts of both the airframe weight and the maintenance cost have been detrimental to the lightweight CFRPs; in addition, there is a need of conductive jumper design for the lightning arc prevention around propulsion systems, fuel systems and electricity systems. Therefore, the sacrificial grid for cathodic protection, which can attain both corrosion prevention and a reasonable conductivity, is an effective option for CFRP/Al airframe protection from galvanic corrosion.