NASCIMENTO, A. V. ; SILVA, T. C. ; GOUVEA, L. A. ; AMARAL, R. A. ; MOREIRA, R. M. ; BANDEIRA, M. C. E. ; Margarit-Mattos, Isabel Cristina Pereira .
Resumo: The effects of pressure cycles and CO2 were characterized for three commercial anticorrosive composite coatings. N2 was also used for comparison purposes. The temperature and pressure range include CO2 supercritical state. The coatings performance was evaluated by visual inspection, pull-off adhesion measurements, impedance and microscopy. The aim is not ranking performance, but to evidence modes of failure and highlight the importance of a protocol including thermo-mechanical evaluation, whenever CO2 and pressure cycles are concerned. Complementary techniques include permeability to CO2, water absorption measured by gravimetry and viscoelastic properties measured by dynamic mechanical analysis. The coatings viscoelastic properties are closely related with performance in such experimental conditions. The presence of water enhanced the pressure cycles effects. The coatings performance becoming more impaired by CO2 than by N2, could be justified by change of physical state of CO2 during the pressure cycles and its cryogenics. Voids within the coating layer seem to enhance cracking during pressure cycles and must be minimized by formulation development and proper coating application methods.
