Search results for "CORROSION"

Protective mechanisms occurring on zinc coated steel cut-edges in immersion conditions

2011

Abstract Electrochemical processes occurring on the cut-edge of a galvanized steel immersed in NaCl solutions were studied using numerical simulations, and in situ current and pH profiles measured over the cut-edge. These results clearly demonstrate that only the steel surface remote from the zinc coating is cathodically active, oxygen reduction being strongly inhibited in the vicinity of zinc. This trend was confirmed by local polarization curves recorded on these distinct areas. Ex-situ AES and SEM analysis and cathodic polarization curves in solutions containing Zn 2+ ions led to conclude that this cathodic inhibition was related to the fast nucleation of a dense Zn(OH) 2 film on the ste…

Influence of long-term ageing in solution containing chloride ions on the passivity and the corrosion resistance of duplex stainless steels

2011

Abstract The influence of long-term ageing in NaCl on the passivity and the electrochemical behavior of UNS S32304 is studied. The passive film thickness, the Cr/Fe ratio and the chloride content were significantly increased after ageing. The chloride distribution depends on residual stresses, sample microstructure and surface preparation. Local electrochemical measurements revealed that pitting potentials are between 250–550 mV vs. SCE after electropolishing. The higher the chloride content, the lower the local pitting potential. It was also shown that the presence of chloride was balanced by the enrichment in chromium after ageing. Then no pitting potential could be measured.

Influence of plastic deformation on the microstructure and corrosion behaviour of Ti–10Mo–4Zr and Ti–6Al–4V alloys in the Ringer’s solution at 37°C

2015

Abstract The influence of plastic deformation on the microstructure and passivity of Ti–6Al–4V and Ti–10Mo–4Zr is studied. The content of titanium-based compounds in the passive film formed on the alloys increases under straining. In the region where necking occurs, the β-phase content drops in Ti–6Al–4V. The grain orientation spread increases with increasing strain. The quality index of EBSD maps is affected on Ti–10Mo–4Zr (dislocation structures along preferential orientations). The corrosion behaviour is investigated in the Ringer’s solution (37 °C). Results obtained in the anodic and cathodic domains are discussed considering changes described previously.

Mechanical properties and corrosion behaviour after scratch and tribological tests of electrodeposited Co-Mo/TiO2 nano-composite coatings

2019

International audience; The micro-mechanical (Young’s modulus and hardness) and tribological properties, as well as the scratch resistance of Co-Mo/TiO2 nano-composite coatings were investigated. The coating was found to be harder and stiffer than the substrate (pure cobalt). Low residual stresses were also derived from Stoney’s equation (type I stress). The corrosion behaviour after tribological and scratch tests was studied in Ringer’s solution. Dry sliding of the coating against an alumina ball at the load of 1 N or 2 N over the same distance had nearly no influence onthe anodic branch of the polarisation curves. By contrast, the current density in the cathodic branch (oxygen reduction r…

NaCl induced corrosion of Ti-6Al-4V alloy at high temperature

2016

International audience; This paper presents a study on the Ti-6Al-4V behaviour in presence of NaCl deposit under dry and moistair environments at 560◦C. The results evidence a detrimental effect of the NaCl deposit with a synergisticeffect in presence of moist air environment. Treatments under dry and moist air with NaCl deposit for600 h, lead respectively to weight gains per unit area 5 and 15 times higher than observed under classicoxidation in dry air. Enhancement of the corrosion phenomenon is attributed to the presence of gaseousmetal chlorides, leading to the establishment of an active corrosion process.

A grain-scale model for high-cycle fatigue degradation in polycrystalline materials

2018

Abstract A grain-scale three-dimensional model for the analysis of fatigue intergranular degradation in polycrystalline materials is presented. The material microstructure is explicitly represented through Voronoi tessellations, of either convex or non-convex domains, and the mechanics of individual grains is modelled using a boundary integral formulation. The intergranular interfaces degrade under the action of cyclic loads and their behaviour is represented employing a cohesive zone model embodying a local irreversible damage parameter that evolves according to high-cycle continuum damage laws. The model is based on the use of a damage decomposition into static and cyclic contributions, a…

The Effect of Deposited Rare Earth Oxide Films on High Temperature Corrosion Behaviour of Different Metals and Alloys

1995

A combined computational and experimental study on the mild steel corrosion inhibition in hydrochloric acid by new multifunctional phosphonic acid co…

2020

Two triazole derivatives with phosphonic acid as pendent group, namely [3-(4-phenyl-[1–3]triazol-1-yl)-propyl]-phosphonicaciddiethylester (PTP) and [3-[4-(4-dimethylamino-phenyl)-[1–3]triazol-1-yl]-propyl]-phosphonic acid diethylester (DMPTP) were synthesized and fully characterized using NMR spectroscopy, Mass spectrometry, Infra-Red (FT-IR) spectroscopy and elemental analysis. The synthesized multifunctional heterocycles were investigated to inhibit the corrosion of mild steel in acidic solution HCl (1 M) by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and weight loss measurements. The results of the different corrosion measurement techniques are in goo…

Optimisation of metallic interconnects for hydrogen production by high temperature water vapour electrolysis

2012

For economical and environmental reasons, hydrogen is considered as a major energetic vector for the future. Hydrogen production via high temperature water vapour electrolysis (HTE) is a promising technology. A major technical difficulty related to high temperature water vapour electrolysis is the development of interconnects working efficiently for a long period. Working temperature of 800°C enables the use of metallic materials as interconnects. Chromia forming alloys are among the best candidates. The interconnect material chosen in the present study is a ferritic stainless steel with 18% chromium content. High temperature corrosion resistance and electrical conductivity of the alloy was…

Electrochemical Investigation of Hydrogen Evolution and Absorption Phenomena in Nickel Based Electrodes

1996

Due to its potential for industrial applications, hydrogen absorption in metals has attracted continuous interest. Understanding the hydrogen chemistry in metals is crucial due to the significance of hydrogen-metal interactions in important industrial and technical applications such as catalysis, H-fuel containment, corrosion and embrittlement of metals and rechargeable metal hydride batteries [1–2].