Estudos comparativos da proteção contra corrosão de diferentes óleos vegetais encapsulados em microcápsulas de poli(ureiaformaldeído)

Abstract

Corrosion has a great impact on the deterioration of metallic structures and equipment, causing, besides a significant cost in repairing or replacing them, a danger to the population. There are several approaches used as methods of protection against corrosion but the most widespread is the application of organic coatings, the paints, which protect the metal surface forming a barrier for agents. A problem observed with this alternative is that the paints occasionally present microcracks caused by physicochemical processes and, once cracked, the coating becomes inefficient in that region. A common process to increase the efficiency of coatings is to make them "smart". The term smart coatings refers to coatings capable of self repair, without the need for human interference. One way of achieving such a characteristic is by incorporating microcapsules into the coating, which contain as core material compounds capable of covering the damaged area, such as resins and drying oils, after disruption of the microcapsule. The objective of this work was to evaluate the efficiency of the corrosion protection of microcapsules containing tung oil and copaiba using stereoscopic images at different immersion times and of the electrochemical tests, open circuit potential (OCP) and polarization curves (Tafel analysis). For this purpose, carbon steel plates were painted with three different systems: one with automotive primer control, one containing 3% tung oil microcapsules, and one containing 3% copaiba oil microcapsules. A cross-cut was performed using scalpel in the systems to promote the release of the oils and after drying electrochemical cells were assembled using as electrolyte NaCl 3.5%. After the tests, it was verified that in the OCP analyzes the plate containing tung microcapsules obtained more positive final values than the control system and containing copaiba microcapsules, being more protective, the stereoscope images corroborate with the OCP results and the polarization curve analyzes also indicated that the microcapsules containing tung oil offer better corrosion protection than the copaiba oil microcapsules in the system studied.