Síntesis y caracterización de “tanatos” de lantano como inhibidores de la corrosión

AUTOR(ES)
FONTE

Matéria (Rio J.)

DATA DE PUBLICAÇÃO

19/07/2018

RESUMO

ABSTRACT Tannins are polyphenols synthesized by plants. They are found in Quebracho (Schinopsis Balansae) wood, Tara (Caesalpinia spinosa) fruits, etc. They have been incorporated in the coating industry as "antifouling" agents and as corrosion inhibitors in acidic solutions. Moreover, lanthanum solutions have a great inhibitory effect over SAE 1010 steel corrosion. The aim of this study was to obtain two types of lanthanum "tannate" with low solubility, so they can be incorporated as corrosion inhibitors in temporary protective coatings, those that protect the metal during transportation and storage. Eventually, they could also be employed in anticorrosive paints. Two types of "tannates" were obtained with two commercial Tara and Quebracho tannins and 0.1M La(NO3)3x 6H2O. The pigments were characterized by Fourrier transformance infra-red spectroscopy (FTIR) and their solubility was determined by the Folin-Denis technique. The protective action of "tanates" on SAE 1010 steel was evaluated by polarization curves and corrosion measurements in NaCl solution. The protective film formed on the steel immersed in the "tannate" suspension was observed by scanning electron microscopy and characterized by dispersive X-ray spectroscopy. Both "tannates" shifted the corrosion potential to more positive values and the polarization resistances were one or two orders of magnitude higher than the controls (solution without inhibitor and different concentration of commercial tannin solutions). On the other hand, the quantification of soluble metal cation and oxidizable material suggests that no premature lixiviation will occur from the coating and they can perform their protective properties for a suitable time.

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