Flow is central to the operation of wells and pipelines and can be postulated to govern the formation of protective corrosion product layers, which is critical to overall infrastructure integrity. However, the phenomena involved remain poorly understood. Therefore, the main objective of this work was to investigate the effect of flow on the heterogeneous precipitation of FeS and FeCO3 as corrosion products on mild steel. Initial corrosion studies were conducted in an autoclave stirred by an impeller. The tests were conducted under quiescent and dynamic conditions for 24 h in an aqueous brine (10 wt.% NaCl, 120°C, 5 bar CO2, 0 and 10-3 mol/l Na2S2O3). The experimental results showed that the increase in rotation speed did not prevent the formation of FeS or FeCO3 crystals. Having confirmed the presence of corrosion product layers, the differences in the trends in corrosion rates may result from the diffusion barrier presented by these layers.

Abstract Pure titanium and various alloys, such as Ti-6Al-4V, are widely used as biomaterials. In this application, surface finish conditions, topography, and surface reactivity determine excellent cellular adhesion and osseointegration characteristics. The study evaluated the influence of four surface finishing treatments (sanding #120, 600, 1200, and polished with 3 µm alumina paste) and three shapes (concave, convex, and flat) on the corrosion resistance of Ti-6Al-4V at 37 °C in simulated body fluid (SBF) through potentiodynamic polarization and electrochemical impedance spectroscopy. The SBF's ionic composition allowed the formation of a stable passive layer with a low presence of pores on the surface. In addition, the combination of polished surface and convex shape showed the best electrochemical passive behavior.