The electro-polishing of C- steel in ortho-phosphoric acid containing methanolic plant extract

Abstract

The electro-polishing behavior of C- steel in ortho-phosphoric acid using the galvanostatic polarization and weight loss methods was ascertained. This was inspected via anode potential–limiting current relationship measurement and comparison in solution of regularly mounting concentrations (from 50 to 1800 ppm of methanolic Marjoram (Origanum majorana), Coriander Seeds (Coriandrum sativum), Chamomile (Matricariarecutita), and Guava leaves (Psidium guajava L)) and influence of temperature on the dissolution kinetic were investigated. Surface morphologies, roughness and reflection of investigated specimens were inspected with a scanning electron microscope (SEM), Profilometry, atomic force microscope and Vis-IR Spectroscopy. Addition of methanolic plant extract to electro-polishing solution results in a lower limiting current. This confirms the mass transport of dissolved species from the anode surface to the bulk of solution as the rate-determining step in the presence of plant extract in all concentrations investigated. Retardation percentage gained from mass loss measurement are comparable with those obtained from measurements of galvanostatic polarization. Results based on microscopy, surface profile measurement and spectroscopy indicate that, addition of methanolic plant extract, a discrete enhancement in the surface texture was observed. Addition of 500 ppm of marjoram (Origanum majorana), coriander (Coriandrum sativa), chamomile (Matricariarecutita) and guava leaves (Psidium guajava L), the degree of surface brightness and reflectance are increased to 64.9, 56.59, 27 and 24.5 respectively relative to electro-polishing electrolyte free solution 16. The roughness (Ra) decreased from 2.7 µm to 0.52 µm without addition of any material. Ra values are 0.28, 0.23, 0.21 and 0.17 μm in the presence of guava leaves (Psidium guajava L), chamomile (Matricariarecutita), coriander seeds (Coriandrum sativum) and marjoram (Origanum majorana). Surface morphology study confirmed that addition of plant extracts to C-steel dissolution bath enhance surface appearance and its texture quality to great extent.