Surface and electrochemical corrosion analysis of niobium oxide film formed in various wet media

Niobium metal has a wide range of applications in medical devices, nuclear applications, and solar cells. Therefore, niobium corrosion behavior and oxide film formation mechanisms are of great interest. Steady-state polarization and a.c transient techniques were employed to determine the effective capacitance, oxide film thickness, and the corrosion behavior of niobium through the time-constant distribution. In this report, we describe a cost-effective wet chemical method of surface treatment of niobium metal for the study of the metastable oxide film (Nb2O5) formed in different media such as NaCl, NaOH, HCl, and H2SO4 solutions. The investigations confirmed a time-dependent formation and dissolution of a protective oxide layer in all the tested media at different potentials, however, recommends short immersion time ( 1 h for NaCl and NaOH. The work developed a new understanding of the niobium corrosion behavior through effective capacitance and film morphology

Comparative evaluation of corrosion behaviour of carbon steel (C1020) in different biodiesels: Synthesis, characterization and electrochemical investigations

The environmental concerns and government regulations have led to a surge in preparation of biodiesels as one of the main components for renewable and alternative fuels from cost effective biowastes. The degradation of biodiesel during storage produces organic acids that could lead to the corrosion of component parts of the engine thus it is imperative to define the rate of corrosivity of this golden alternative before its application. The current study utilizes electrochemical methods (OCP, EIS and PDP) in addition to advanced techniques such as SEM, UV–vis and FTIR to investigate the comparative corrosion behaviour of three biodiesels namely; jatropha oil biodiesel (JOB), neem oil biodiesel (NOB) and waste cooking oil biodiesel (WCOB) on carbon steel. The surface morphology of the post corrosion steel samples as characterized by SEM revealed differences in surface damage due to corrosion in the various systems. The study further inferred that the investigated biodiesel requires specific carbon steel component type for compatibility and effectiveness in fuel delivery and storage systems of automobile engines which were evident by the different corrosion degradation rates (103, 74 and 51 mpy) for JOB, NOB and WCOB respectively. The overall results showed differential corrosion rates of the order JOB > NOB > WCOB on carbon steel under similar experimental conditions