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

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.