What Does Adhesion Failure Mean?
Adhesion failure refers to the state when the adhesive loses adhesion from one of the bonding surfaces. It is characterized by the absence of an adhesive on one of the material surfaces. Surface treatment is required to fix this failure.
Understanding this state requires a careful analysis of adhesive failures. The failure may be located at the bonding interface with a very thin layer. This interface may be contaminated during surface preparation of the adherend surface and while applying an adhesive.
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Corrosionpedia Explains Adhesion Failure
Adhesion failure happens at the interface between the adhesive layer and the adherends. This failure results from the hydration of the chemical bonds, which form the connection between the adhesive and the bonding surface. An adhesive bond fails when either the adhesive loosens from the substrate or when the adhesive breaks apart.
Adhesion failure is mainly substrate adhesion failure and intercoat adhesion failure. Substrate adhesion failure occurs when the whole coating system that has been used for bonding can be easily detached from the substrate. It shows the absence of adhesion of the whole coating system that has been applied. Causes of this failure are linked to three things:
- Inadequate or non-existent blast profile
- The presence of surface contaminants
- An under-cured film
Intercoat adhesion failure happens when the top coat and primer do not bond. The two primary causes of this failure are:
- An under-cured top coat
- A thick primer coat being applied
A common form of adhesion failure is seen when taping the substrate, which has any one of the following characteristics:
- When substrate is unstable (use a primer to stabilize/solidify the substrate)
- When surface energy of the substrate is too low
It is always advisable to do an adhesion test to check the performance of the adhesion. A clean and dry substrate will give best adhesion results.