Tribological behavior of stainless steel in sulfuric acid in the presence of Thymus zygis subsp. gracilis essential oil: experimental and quantum chemical studies

Abstract

Abstract To reduce the use of synthetic compounds as wear-corrosion inhibitors, and substitute them with new ecological compounds, we are interested in evaluating the effect of the essential oils against the tribocorrosion. The present paper describes the effect of adding Thymus zygis subsp. gracilis (TZ) essential oil (3 g·L−1) on AISI 304L tribocorrosion behavior in 0.5 M H2SO4. As a result, the addition of this essential oil decreases the tribocorrosion rate [E (%) = 84.38], the value of friction coefficient, and the energy dissipated during sliding wear, in comparison to those recorded for dry environment and 0.5 M H2SO4. In addition, the essential oil improves the surface morphology of metal as shown by the scanning electron microscopy and energy dispersive X-ray and the three-dimensional optical profiler analysis. In addition, the modeling approaches of experimental results, involving the density functional theory, the electrostatic potential, and the Monte Carlo methods, show that thymol (42.5% of TZ oil) is the best corrosion and tribocorrosion inhibitor that adhered to the stainless steel surface and offers a greater coverage area to block the metal wear-corrosion. According to the obtained results, the TZ essential oil can be used in the food industry to prevent the wear of materials.