Mitigation of Galvanic Corrosion in Bolted Joint of AZ31B and Carbon Fiber-Reinforced Composite Using Polymer Insulation

Abstract

The use of polymer insulation to mitigate galvanic corrosion was examined for bolted joints of AZ31B Mg alloy and carbon fiber-reinforced composite. To assess the corrosion behaviors of bolted joints with and without polymer insulation, solution immersion and salt spray exposure (ASTM B117) tests were conducted, and the corrosion depths and volumes were determined for the joint specimens after the tests. The polymer-insulated bolted joints exhibited much lower corrosion depths and volumes, highlighting the effective mitigation of galvanic corrosion. The reductions of joint strength in the post-corrosion joint specimens were relatively small (up to ~10%) in the polymer-insulated group but greater (up to 90%) in the group with no insulation. Cross-sectional characterization of post-corrosion joints with polymer insulation revealed local pits developed on AZ31B under galvanic influence, indicating that limited galvanic attack (that did not decrease the joining integrity significantly) could still occur during a long salt spray exposure (~1264 h) owing to the permeation of an aqueous corrosive medium.

Corrosion monitoring at the interface using sensors and advanced sensing materials: methods, challenges and opportunities

“…The polymer insulation materials or protective coatings between the interfaces can avoid the direct contact of the different materials and stop the electron's transfers. Selection of the materials can help to reduce the potential difference of the materials and minimise the driving force [22,27]. In general, galvanic corrosion cell does not need any external power source.…”

Comparative Study of the Effects of Galvanic Corrosion on the Strength and the Failure of Aluminium and Stainless Steel Bolted Joints

“…Research and development efforts were devoted to defining standards or methods to reduce the effects of galvanic corrosion on the integrity of multi-material structures (Langøy, 2023;EN 1090EN -3, 2019NORSOK Standard -M-102, 2015; NORSK Standard -M-001: 2014/A1, 2021). For example, EN 1090-3 (EN 1090-3, 2019 and NORSOK M-001 (NORSK Standard -M-001: 2014/A1, 2021) specifies that when joining dissimilar materials such as aluminium and steel, the aluminium surfaces shall be treated (e.g., coating) or the different metals shall be separated by an isolation to avoid galvanic corrosion (Suo et al, 2021;Melhem, 2019;Jun et al, 2021). In the case of high load applications where non-metallic isolation can't be applied, the standard recommends bimetallic shim or insert as an alternative solution (NORSOK Standard -M-102, 2015).…”

“…Tensile-shear test is commonly used to assess the static bearing force and failure mode of bolted assembly (Li et al, 2021;Kong et al, 2021;Denkert et al, 2022;Boretzki and Albiez, 2023;Delzendehrooy et al, 2022;Kong et al, 2021). In the current work, the testing setup is equipped with three optical cameras and digital image correlation (DIC) software to provide full-field measurements of plates displacements and bolt's rotation.…”

“…A critical challenge to the assessment of corrosion's effect on loading capacity lies in the assessment of the effects on preloading and frictional behaviour. Tribocorrosion studies on materials like aluminium and stainless steel demonstrated an increase in their friction coefficient due to corrosion, affecting contact shear forces (Zhang et al, 2015;Li et al, 2021;Zhang et al, 2018). Material degradation due to corrosion cause reduction in the preloading and degradations of mechanical performance (Kong et al, 2021;Kong et al, 2022;Jiang et al, 2022;Kim et al, 2016;Li et al, 2021).…”

“…Tribocorrosion studies on materials like aluminium and stainless steel demonstrated an increase in their friction coefficient due to corrosion, affecting contact shear forces (Zhang et al, 2015;Li et al, 2021;Zhang et al, 2018). Material degradation due to corrosion cause reduction in the preloading and degradations of mechanical performance (Kong et al, 2021;Kong et al, 2022;Jiang et al, 2022;Kim et al, 2016;Li et al, 2021). At the same time, it is known that the corrosion products built up under the washer, nuts and bolt head increase the clamping force leading to serious issue for the design of bolted assembly (Bickford, 1995).…”