Effect of Green Corrosion Inhibitors on the Corrosion Behaviour of Nanocrystalline W-42Cr-5Ni Alloy in 0.5 M NaCl Solution

Abstract

A corrosion inhibitor is a chemical substance, which when added in a small concentration to a corrosive environment, effectively decreases the corrosion rate of a metallic substance that exposed to the environment (1). The corrosion control method of metals and alloys using the inhibitors is a fundamental academic and industrial concern that has received a considerable attention nowadays (2). Effects of three eco-friendly green corrosion inhibitors of sodium salts of nitrite, molybdate and tungstate in different concentrations (i.e., 200-2400 ppm) on the corrosion behaviour of the sputter-deposited ternary nanocrystalline W-42Cr-5Ni alloy were studied using corrosion tests and electrochemical measurements in 0.5 M NaCl solution open to air at 25ºC. The use of these corrosion inhibitors enhanced to increase the corrosion resistance properties of the alloys as a result the corrosion rate of the W-42Cr-5Ni alloy was decreased with increasing the concentrations of sodium nitrite from 200 to 2400 ppm as shown in Fig. 1(a). The inhibition action of the tested inhibitors was found to obey the Langmuir isotherm model and the inhibition efficiency was found to increase with increasing the inhibitors concentration. Based on the open circuit potential measurements, the most efficient corrosion inhibitor was found to be sodium nitrite than other sodium molybdate and sodium tungstate in 0.5 M NaCl solution open to air at 25ºC. Uhlig, R. W. Revie, Corrosion and Corrosion Control; an Introduction to Corrosion Science and Engineering, 4rd edition, John Wiley and Sons, New York, 2008.J. Bhattarai, Frontiers of Corrosion Science, 1st edition, Kshitiz Publ., Kathmandu, 2010.