Portugaliae
Electrochimica Acta

The aim of this manuscript was to optimize the IE(%) of a pyridazine derivative (MDP) for hindering MS corrosion in a 1 M HCl solution. To identify the most influential parameters affecting CI, a study was conducted using a Doehlert matrix and Nemrod software. Based on preliminary knowledge, three parameters (Ct from MDP, IT and T) were selected. IE(%) was evaluated by analyzing PDP intensity-potential curves and interpreting the obtained results. The novelty of this research stems from the methodical application of DoE methodology to optimize CI, which offers notable advantages such as reduced test requirements, and the ability to discern interactions between factors. The findings revealed a remarkable IE(%) of 96%, under optimal conditions: Ct from MDP of 0.3 x 10-3 mol/L, IT of 12 h and T of 303.15 K. Keywords: corrosion; DoE; inhibition; MDP; MS; PDP.

MS is the most commonly used alloy in industries, due to its remarkable features such as high thermal requirements, low cost, easy availability, high strength, durability and electrical conductivity. In recent years, scientists have focused on green inhibitors obtained from plants, fruit extracts and essential oils. Besides being environmentally friendly, in terms of corrosion resistance, plant extracts are becoming increasingly important, due to their low cost and toxicity, and high availability. Additionally, they are rich in organic compounds with polar atoms, such as O, P, S and N, containing multiple bonds in their molecules, through which they can adsorb onto the metal surface, forming a protective film, by various adsorption isotherms. This paper provides a review on research works done on MS corrosion control by naturally occurring plant extracts as corrosion inhibitors in H2SO4 solutions. Keywords: corrosion inhibition; EIS; H2SO4; MS; plant extracts; PDP; WL.

The background motivation of this paper was SPP, which refers to surface waves occurring at terahertz frequencies, as widely used wave in optics industry. This wave has been produced during the electromagnetic field interaction with oscillations of free metal electrons. Due to their improved field and intense incarceration close to the metal surface, SPP waves have been extensively employed for high sensitivity sensors and small photonic circuits. The method herein proposed was a BPF based on designer-SPP by means of central frequency and adjustable bandwidth. It was adjusted via varactor diodes placed in different positions in the T-shaped resonator. Considering the constraints and strengths of high field SPP polarizations, hearing and coupling becomes weaker than that from the usual microstrip. Analytical and evaluation methods comprised three inductors assessed at different locations of the T-shaped resonator, which were controlled by DC bias voltage. Transition from the microstrip QTEM mode to SPP misleading mode was performed to excite SSPP based on the T-shaped resonator with g-distance coupling. Keywords: adjustable central frequency; BPF; QTEM, SPPP.

This study investigated the electrochemical performance of pure Al and Al alloy anodes in Sw environments for CP real-world applications, such as marine environments, under various operational conditions. Experimental results showed a significant activation of Al alloy anodes compared to pure Al, as indicated by a more anodic shift in OCP and a marked increase in jcorr. The impact of varying DAC and changes in Sw conductivity on CP performance was also herein explored. These factors notably influenced both Ecorr and j from CP, resulting in deviations from expected design values. Keywords: Al alloy; CP analysis; electrochemical calculations; modeling investigations; Sw.

This review overviews recent advancements in studying corrosion scales formed on CS and low alloy steel surfaces in CO2/H2S environments. It discusses the chemical reactions, kinetics, mechanisms, classifications, influential factors, formation rates, types, and inhibitive properties of corrosion product scales that develop on steel surfaces. It thoroughly investigates phase transitions, the nature and composition of corrosion product scales, and their impact on the corrosion process by influencing the kinetics of anodic reaction (metal dissolution) and/or cathodic reaction (oxygen reduction/HER), which protect the corroding steel surfaces. Lastly, it emphasizes crucial research areas, knowledge gaps, future perspectives, and approaches for scale mitigation. Keywords: CO2/H2S corrosion; steel corrosion, corrosion mechanisms; corrosion scales; FeCO3; FeS.