The Role of Cyclic Relative Humidity in Driving Coating Delamination and Subsequent Corrosion Damage Morphology

摘要

The difficulty of replicating service-environment corrosion failure modes in laboratory testing is a well-known and well-documented challenge facing the atmospheric corrosion and coatings communities. Many recent studies have highlighted the importance of cyclic variations of Relative Humidity (RH) to produce corrosion damage similar to real-world damage. In this work, the role of RH variations on coating adhesion and morphology of attack in the vicinity of a galvanic fastener are shown. Digital image analysis techniques are used to quantify the damage produced by differing RH cycles in the laboratory. A comparison of the damage produced and what is observed in field samples from two coastal environments is also presented. An attempt is made to identify the critical RH conditions required to drive different coating delamination rates and subsequent corrosion damage.