Corrosion inhibition of weldment by Nephelium lappaceum peel extract in 3.5% NaCl solution

Abstract

Nephelium lappaceum peel Extract (NPE) is effective to control carbon steel weldment corrosion in acidic solution.This study analyzes NPE performance (0 to 60 ppm) as corrosion inhibitor on weldment in 3.5% NaCl. Potentiodynamic polarization was used to investigate corrosion rate and inhibition performance. The results revealed that NPE has strong effect (83%) on heat affected zone (HAZ) and on base metal (BM) (62%) and on weld metal (WM) (71%). NPE acted as mixed type inhibitor on all weldment areas. On weldment areas, there was physisorption (WM and HAZ) following isothermal Langmuir, but on BM chemisorption might also happen. The results surface analysis, FTIR and UV Vis are in line, indicating that inhibition behavior happened due to the formation of adsorbed layer on the weldment surface. This study revealed that NPE had different performance in each region and solution temperature.

Keywords

• Chemisorption
• Corrosion
• Inhibitor
• Physisorption