World Pipelines – Coatings & Corrosion 2015

Cathodic disbondment or self-healing?World Pipelines – Coatings & Corrosion 2015 – Cathodic Disbondment or self-healing? Nathan Muncaster, Polyguard Products, USA, and Luc Perrad, Expartech, Belgium, discuss cathodic disbondment testing and its importance within the industry. By definition, cathodic disbondment is the loss of adhesion between a coating and its metal substrate, due to cathodic chemical reactions that take place in the interface of steel and coating. In cathodic protection system, current passing through the metal frees hydrogen gas and oxidative molecules like chlorine and hypochlorite-ions, causing coating disbondment. This current passes only through the metal exposed to the electrolyte where the coating is in default. The current flow amount depends on the size of the coating fault. If the size of the fault increases, the current increases, causing more cathodic disbondment. If there is no coating fault, then cathodic disbondment does not occur. [Read More…]