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Cathodic Blistering

Definition - What does Cathodic Blistering mean?

Cathodic blistering is an experimental approach intended to prevent corrosion in the area of a metal's surface that has been uncovered due to blisters that have burst. Cathodic blistering provides protection through a galvanostatic charge to the uncovered area.

In cathodic blistering, a galvanic reaction occurs at the cathodic side and helps to protect the metal that became inadvertently exposed due to dents and chips when the blisters burst. The cathodic protection is provided to the uppermost coating or paint layer. When blisters subsequently form, a cathodic reaction occurs at the interface, which releases a hydroxyl ion and some positive ions. These hydroxyl ions and positive ions release the osmotic pressure inside the bubble, which splits the thin polymer coating evenly over the exposed area, thereby protecting the areas that became uncovered.

Corrosionpedia explains Cathodic Blistering

Blistering is the formation of broken or unbroken bubbles of any size, which are under or within a coating at the paint/metal interface. Although blisters can form between layers of paint, these are less common. Blisters are often liquid filled and may take the form of clusters (or rashes). Blistering is the result of adhesion failure and can cause adhesion failure, and is therefore catastrophic.

Blistering is basically a flaw in a coating or paint application where small bubbles appear. After the bubbles burst areas of the metal's surface are no longer covered by the coating.

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