Regresar

The influence of hexamethylenetetramine on the corrosion and hydrogen permeation of type API 5L-X52 steel

Abstract:

The inhibitive effect of hexamethylenetetramine on the corrosion and hydrogen permeation behaviour was evaluated on a type API 5L-X52 steel in 1 N H2SO4 solution. Potentiodynamic polarization curves were employed to determine the electrochemical behaviour of the steel, while the Devanathan-Stachurski technique was used to estimate the hydrogen permeation rate. Optical and scanning electron microscopies and energy dispersive X-ray analysis were used for surface analysis. Additionally, to detect the hydrogen damage in the steel, an ultrasonic technique based on the sound wave attenuation was employed. The obtained results clearly indicate that Hexamethylenetetramine inhibits efficiently the corrosion of the steel but increase the quantity of absorbed hydrogen in the bulk metal. The organic compound seems to have a specific influence on the hydrogen evolution reaction, reducing the active site numbers were hydrogen could be reduced and partially blocking the recombination of atomic hydrogen to molecular hydrogen on the steel surface. Apparently, this effect leads to a larger hydrogen absorption into the metal lattice. In the samples that were tested in solutions containing inhibitor, considerable superficial damages such as blistering and hydrogen induced cracking were observed. Moreover, the higher inhibitor concentration, the larger is the mechanical damage observed in steel.