SHAPE FORMING
AUTONOMIC
Trials have proven that this low-VOC waterborne self-healing coating is as good as its more obnoxious solventborne cousins
S
elf-healing functionality is extremely useful for effective corrosion resistance. Case in point, consider that although
they remain highly regulated known carcinogens, chromate conversion coatings and primers are still used for the protection of critical metal assets by the US Department of Defence due to their effectiveness. A key component of the corrosion resistance afforded by coatings containing chromates is the ability to store Cr(VI) within the coating system such that damage to the coating system allows the Cr(VI) to leach out into the site of damage where it is then reduced to form a highly protective chromium oxide film. Note that this mechanism, which
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has been referred to as ‘self-healing’, can be initiated by the exposure of the underlying substrate as a result of damage to the coating system. Due to the carcinogenicity of chromates and the regulation of their use, the vast majority of protective coating systems are chrome-free and, as such, do not exhibit such ability to maintain corrosion resistance after damage. When these coatings are damaged, the underlying substrate is exposed to the environment, leading to corrosion. Unless promptly repaired, corrosion on the substrate will propagate at the coating/substrate interface, compromising the coating’s adhesion to the substrate and, consequently, its ability to protect it.
ADDING SELF-HEALING FUNCTIONALITY Based on the importance of the self- healing functionality in the corrosion resistance offered by coating systems containing chromates, it stands to reason that the future of effective
Damage before creep takes hold
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