Effect of anodizing on galvanic corrosion behavior of T300 CFRP/5083P‐O Al bolted joints

Abstract

AbstractT300 carbon fiber reinforced polymer (CFRP) and 5083P‐O aluminum (5083P‐O Al) alloy bolted joints have been used in high‐speed trains due to the advantages of light weight and high strength. However, high potential difference between the CFRP and 5083P‐O Al will induce galvanic corrosion and result in accelerating corrosion rate of 5083P‐O Al, which is a potential risk for its engineering applications. In this work, combination with the electrochemical analysis, surface and cross‐section corrosive morphologies analysis, the galvanic corrosion behavior between CFRP/5083P‐O Al bolted joints with and without anodizing in 3.5 wt.% NaCl spray was investigated. Results indicated that severe corrosion occurred on unanodized 5083P‐O Al in the coupled regions of the CFRP/5083P‐O Al bolted joint due to galvanic corrosion. With the content of sulfuric acid increasing, the thickness of each Al2O3 layer and atomic oxygen content increases significantly. 5083P‐O Al anodized by the 135 g/L H2SO4 + 8 g/L H3BO3 mixed solution had the favorable Al2O3 film, which increased the resistance of 5083P‐O Al by roughly three orders of magnitude, effectively improving the corrosion resistance of 5083P‐O Al.