Cathodic Delamination
Cathodic disbondment is the detachment of organic coatings on metal due to cathodic reactions under a paint film. At defects, an alkaline environment is created that destroys the interfacial adhesion of the protective coating.
Physicochemical mechanism of action
Cathodic disbondment occurs when cathodic current flows at electrolytes or coating film defects. This leads to chemical reactions in which organic compounds are degraded and metal ions are dissolved.
Metallurgical relevance & risks when welding
Cathodic disbondment can lead to coating wear and corrosion. It can significantly shorten the life of paints and coatings and make the metal more susceptible to cracks. If mishandled, it can also lead to welding defects such as porosity or distortion.
Workshop practice & instructions
To avoid cathodic disbondment, paints and coatings should be checked regularly. If there are signs of wear or corrosion, the surface should be cleaned and recoated. When welding, use suitable protective agents and ensure proper electrolyte isolation.