Interfacial cracking between an epoxy-based composite coating and a rigid substrate under thermal loading

Owing to the difference in thermal expansion of an epoxy coating layer and a substrate, existing pre-cracks/defects in the coating/substrate interface may suffer high thermal stresses in the coating system. Using Finite Element Analysis (FEA) based on ABAQUS, this study showed that pre-cracks initiated at the edge were more severe than those at the centre. Once delamination was triggered by the temperature change induced thermal loading, it propagated quickly along the coating/substrate interface, which was consistent with experimental observations. It was also found that the coating thickness and temperature change magnitudes were important factors affecting the fracture behaviour of the coating. Moreover, incorporation of fillers into an epoxy matrix was found to reduce the driving force (given as stress intensity factor K or J-integral) of an interfacial crack. Hence, the effects of filler parameters such as the elastic modulus, thermal expansion coefficient, volume ratio, aspect ratio and orientation, etc. were conducted to provide useful results for improving the design of epoxy composite coatings for different engineering application.