Effects of coating degradation on the durability of rubber-to-metal bonds in corrosive salt environments

Abstract

The use of rubber-metal components in various engineering structures, including bridges, offshore platforms, buildings, and automotive parts, is widespread. A strong rubber-to-metal bond is critical to ensuring long-term product reliability. However, environmental factors such as moisture and corrosion can progressively weaken this bond. This study investigates the performance of bonded rubber to a mild steel substrate using three industrial bonding agents (Bonding Systems A, B and C) under corrosive conditions and the degradation of the coating contributes to the loss of adhesion. The bond durability tests were performed using a salt spray test and an alkaline resistance test. The chemical changes within the bonding agents were monitored using Fourier Transform Infrared Spectroscopy. In salt spray tests, all bonded systems failed, with delay times of 25 h for Bonding Systems A and B and 144 h for System C, indicating that Bonding System C has higher resistance to corrosion reactions. An alkaline environment led to a significant degradation of the functional groups of the bonding system, except for Bonding System B. However, the results indicate that these chemical changes do not necessarily result in an immediate loss of adhesion. This suggests that chemical degradation of the polymer alone is not a sufficient indicator of coating performance, as the integrity of the interface can be maintained despite changes occurring at the molecular level.