S. Touzain - Academia.edu (original) (raw)

Papers by S. Touzain

Aluminum coatings are widely studied for the cathodic protection of steel structures. However, al... more Aluminum coatings are widely studied for the cathodic protection of steel structures. However, aluminum has poor mechanical properties and its passivation trend could favor localized degradation in chlorine environment, increasing largely the coating dissolution. In order to improve the sacrificial protection and the mechanical properties provided by the aluminum coatings, several alloying elements have been tested as monolayers, in particular Mo, Mg, and Mn. The use of a single alloying element cannot improve both mechanical and corrosion properties. As a consequence, multilayer configuration appears as a promising solution. Different multilayer configurations have been synthesized associating two elements or alloys: one with good mechanical properties and one with a good sacrificial behavior. This study is focused on the impact of the multilayer configuration on the mechanical and electrochemical properties. Several configurations have been tested: the periodicity Λ was varied between 15 nm and 120 nm. Decrease of the period permits to enhance the corrosion properties of the coatings. The most promising multilayer configuration has been thoroughly investigated. The influence of a plastic deformation on the reactivity was examined. Two different strains have been identified, and the electrochemical behavior of the coating was studied as a function of the strain and compared to pure aluminum.

Progress in Organic Coatings, 2020

Abstract During hygrothermal ageing of organic coatings, water and temperature lead to a coating ... more Abstract During hygrothermal ageing of organic coatings, water and temperature lead to a coating swelling which can be in situ monitored by scanning electrochemical microscopy (SECM). However, it is difficult to separate the respective influence of water and temperature when ageing is performed in aqueous solution. In order to overcome this problem, room temperature ionic liquids can be a solution. In this work, a model DGEBA/DAMP polyepoxide resin, with or without pigments (TiO2) was applied onto steel Q-panels, with a thickness about 100 μm, completely cross-linked, and was aged in a 3 wt.% NaCl aqueous solution. The swelling was measured by SECM for different ageing temperatures in the saline solution. The same epoxy systems were placed in RTIL (1-Ethyl-3-methylimidiazolium ethyl sulfate) and the swelling was measured by SECM at different temperatures. A typical procedure was applied in order to analyze SECM results obtained in RTIL. The results allowed to evaluate the respective contribution of water uptake and temperature to the global coating swelling. The swelling due to temperature was 0.5%/10 °C for unpigmented coatings and 0.3%/10 °C for pigmented coatings while the total swelling was respectively about 5% and 4%, which is higher than the water uptake at saturation. It was then proposed that the swelling excess (about 2% and 1% for unpigmented coating and pigmented coatings respectively) was related to the internal stress relaxation of the polymer network during immersion.

Aerospace Science and Technology, 2017

Abstract The objective of this study was to analyze by three-dimensional finite element method, t... more Abstract The objective of this study was to analyze by three-dimensional finite element method, the effect of the position, number and shape of the bonding defect on the shear stress distribution in the adhesive layer used to joint two aluminum 2024-T3 plates. Numerical analysis allowed us to deduce that the bonding defect presence has a negative effect on the value of the shear stresses in the adhesive layer and therefore the durability of the assembly. Whatever the size of the defect, the maximum stresses are always localized at the adhesive edge. If the overlap length is important, the effect of defect on joint strength is lower.

Progress in Organic Coatings, 2016

Abstract The water sorption characteristics have been determined for two model epoxy systems base... more Abstract The water sorption characteristics have been determined for two model epoxy systems based on the DGEBA resin and two amine hardeners (TETA and DAMP). A particular attention was paid to the curing protocol to control the macromolecular architectures. Using FTIR, DSC and DMTA measurements, it was demonstrated that both network microstructures differ mainly in the polar groups density, the potential crosslinking nodes and the free volume. DGEBA/DAMP system presents a higher free volume fraction and a lower polar groups concentration compared to the DGEBA/TETA system. Gravimetric measurements on free films and EIS experiments onto coated steel Q-panels were carried out to follow the water sorption kinetics at different temperatures (30, 40, 50 and 60 °C). For both epoxy systems, the diffusion processes follow a pseudo-fickian behaviour with two diffusive stages. Solubility and diffusion processes are discussed in relation with the microstructural specificities of the polymer networks using a thermodynamic framework. The main result is that in DGEBA/DAMP and DGEBA/TETA systems, the water diffusion and solubility are mainly governed by a water polar group interaction mechanism.

Journal of Electroanalytical Chemistry, 2014

Electrochimica Acta, 2017

Abstract For many years, the water uptake in organic coatings was measured by EIS and/or gravimet... more Abstract For many years, the water uptake in organic coatings was measured by EIS and/or gravimetry but differences in water content values were found in almost all studies. The Brasher-Kingsbury equation used in the electrochemical analysis (EIS) is often criticized because elementary assumptions may be unvalid. The origin of the discrepancy between both methods is still of interest because many questions remain open and this study aims to provide new insights to these questions. In this work, free films and coatings of a model epoxy-amine system were immersed in a 3 wt.% NaCl solution. The water uptake in free films was evaluated using gravimetric measurements and EIS, using the Basher-Kingsbury equation. The mass of free-films used in the EIS tests was measured and compare to gravimetric measurements while the water uptake (EIS) in free films was compared to that obtained with coatings. It was found that the mass increase of free films tested with EIS was in agreement with gravimetric measurements but was always lower than the water uptake obtained by EIS. Moreover, the water uptake in free films (EIS) was different from that obtained with coatings. In all cases, it was found that the Basher-Kingsbury equation overestimated the water uptake. It appears that the differences between EIS and gravimetric measurements can be analyzed in terms of geometrical effects. Indeed, the swelling in free films and coatings can be monitored by DMA and SECM during ageing. Finally, by mixing the experimental swelling data and the Brasher-Kingsbury equation, the same value of water uptake was obtained by EIS and gravimetry for coatings.

The aim of this study is to perform a finite element analysis of the Von Mises stresses distribut... more The aim of this study is to perform a finite element analysis of the Von Mises stresses distribution in the adhesive layer and of the J-Integral for a damaged plate repaired by a composite patch. Firstly, we study the effect of the fiber orientation, especially the position of the layers that have orientation angle different of 0° from the first layer which is in all cases of our study oriented at (0°) on the J-Integral. Secondly, we evaluate the effects of the mechanical properties of the patch and the use of a hybrid patch on the reduction of stresses distribution and J-Integral. The results show clearly that the stacking sequence for the composite patch must be selected to absorb optimally the stresses from the damaged area and to position the various layers of the composite under the first layer whose fibers orientation will remain in all cases equal to 0°. The use of a hybrid composite reduces significantly the J-Integral and the stresses in both damaged plate and the adhesive ...

Journal of Adhesion Science and Technology

Abstract The effect of an hygrothermal ageing on the mechanical behavior of the bulk adhesive ‘Ad... more Abstract The effect of an hygrothermal ageing on the mechanical behavior of the bulk adhesive ‘Adekit A140 epoxy’ was investigated. The bulk test specimens of the adhesive were immersed in distilled water at various temperatures (20, 40 and 60 °C). Under these conditions, the tensile properties were determined and used in a numerical study about the behavior of bonded assemblies allowing to calculate the J-Integral. The obtained results illustrate the variation of the mechanical behavior of bulk adhesive depending on the immersion time and environmental temperature. The presence of water in the adhesive decreases the tensile strength and the elastic modulus but also increases the ductility of material. These changes in mechanical properties are more important when the percentage of water absorbed increases. The temperature increases the amount of absorbed water in the adhesive, consequently increases the degradation kinetics with the immersion time and directly affect the load transfer rate of the damaged area to the composite patch and therefore the value of the integral J.

Journal of Materials Science

AbstractThis study focused on the influence of a pigment (titanium dioxide at rates of 10 and 20 ... more AbstractThis study focused on the influence of a pigment (titanium dioxide at rates of 10 and 20 wt%) on the hygrothermal ageing of a model epoxy polymer resin (DGEBA–DAMP). An ageing cycle composed of sorption and desorption steps was applied at different temperatures. Gravimetric study was carried out on free films. Results of pigmented samples were compared with those of the resin alone to better understand impact of the titanium dioxide. TiO2 had no major influence on gravimetric curves: water content curves exhibited a pseudo-Fickian behaviour during sorption and Fickian one during desorption. Moreover, results pointed out that pigment did not absorb water. Curve treatment allowed to obtain diffusion coefficient and water content at equilibrium for each step of ageing. Values of diffusion coefficients indicated that titanium dioxide did not have major influence on the beginning of diffusion, whereas it slowed down the end of water uptake. During sorption, water content at equilibrium was dependent on TiO2 amount. After desorption, pigmented systems contained residual water for ageing cycles at high temperature. Finally, results of diffusion coefficients showed that diffusion phenomena were heat dependent. A thermodynamic approach was then used to have access to enthalpy of diffusion ΔH and pre-exponential factor D0. These parameters were impacted by the presence of titanium dioxide. This was mainly due to the presence of additional internal stresses of Type II.

Aerospace Science and Technology

Abstract The objective of this study is to analyze by experimental tests, the effect of hygrother... more Abstract The objective of this study is to analyze by experimental tests, the effect of hygrothermal aging of the patch and the adhesive on the fatigue behavior of a damaged 2024-T3 aluminum plate repaired by a carbon/epoxy patch composite. The effect of the water absorption by the composite patch and the adhesive has a significant effect on the load transfer from the damaged plate and therefore on the delay of the crack propagation. The more water immersion time is important, the less is the fatigue strength of the repaired structure. The experimental results showed that the number of cycles to fracture is directly related to the aging time.

Aerospace Science and Technology

Abstract In this paper, we analyze the variation of shear stresses in the adhesive layer, used in... more Abstract In this paper, we analyze the variation of shear stresses in the adhesive layer, used in a single lap joint, in the presence of variable numbers and positions of defects. The results of the value of maximal shear stresses were used to develop a shear stress probability distribution models in the adhesive of SLJ with presence of one, ten and fifty defects with random position to improve the damage probability. Based on the result found in part-I [1] , a set of theoretical samples was generated and their corresponding histograms using Freedman–Diaconis method. Seven different probability density functions (PDFs) were fitted to these histograms. In each case, a Kolmogorov–Smirnov test was used to evaluate the quality of fit. Finally, after substituting the values of estimated parameters for each distribution, a set of fully defined PDFs have been proposed for the shear stress in the adhesive layer of SLJ in the presence of artificial defects with random positions. This PDF has been used to introduce a new criterion included critical shear stress but also distribution parameters of damage.

Structural Engineering and Mechanics

Surface and Coatings Technology

Progress in Organic Coatings, 2007

A zinc-rich powder coating, applied onto steel substrate, was studied using electrochemical imped... more A zinc-rich powder coating, applied onto steel substrate, was studied using electrochemical impedance spectroscopy (EIS). Before immersion when coating is dry, EIS spectra revealed that the percolation threshold was reached. Then, an equivalent circuit including a transmission line was applied to model electrochemical response. In this model, which considers isolated and semi-isolated zinc particles within the binder, it was found that both phases were equally distributed in the coating.

Journal of Adhesion Science and Technology, 2006

ABSTRACT

Electrochimica Acta, 2008

In this work, hydrochloride polyaniline (PANI-Cl) powder was incorporated as a conductive pigment... more In this work, hydrochloride polyaniline (PANI-Cl) powder was incorporated as a conductive pigment into powder zinc-rich primer (ZRP) formulations in order to enhance the electronic conduction paths between zinc particles inside the coating and the steel substrate (i.e. percolation). Coatings were applied onto steel substrates and immersed in a 3% NaCl solution at ambient temperature.

Applied Surface Science, 2014

ABSTRACT In France, hot water quality control inside buildings is occasionally ensured by disinfe... more ABSTRACT In France, hot water quality control inside buildings is occasionally ensured by disinfection treatments using temperature increases or addition of sodium hypochlorite (between 0.5 ppm and 1 ppm residual free chlorine). This disinfectant is a strong oxidiser and it could interact with metallic pipes usually used in hot water systems. This work deals with the study of the impact of these treatments on the durability of copper pipes. The objective of this work was to investigate the influence of sodium hypochlorite concentration and temperature on the copper corrosion mechanism. Copper samples were tested under dynamic and static conditions of ageing with sodium hypochlorite solutions ranging from 0 to 100 ppm with temperature at 50 degrees C and 70 degrees C. The efficiency of a corrosion inhibitor was investigated in dynamic conditions. Visual observations and analytical analyses of the internal surface of samples was studied at different ageing duration. Corrosion products were characterised by X-ray diffraction and Raman spectroscopy. Temperature and disinfectant were found to considerably affect the copper corrosion mechanism. Surprisingly, the corrosiveness of the solution was higher at lower temperatures. The temperature influences the nature of corrosion products. The protection efficiency is then strongly depend on the nature of the corrosion products formed at the surface of copper samples exposed to the aggressive solutions containing different concentration of disinfectant.

Materials Science Forum, 1998

The effect of addition of conductive pigments like carbon blacks on the corrosion behavior of zin... more The effect of addition of conductive pigments like carbon blacks on the corrosion behavior of zinc-rich powder paints coated steel in artificial sea water was investigated. Open circuit potential measurements were used to characterize the cathodic protection ability and duration. Micro-Raman spectroscopy analysis was performed in order to identify the corrosion products and to follow the penetration of the solution inside the coatings.

Aluminum coatings are widely studied for the cathodic protection of steel structures. However, al... more Aluminum coatings are widely studied for the cathodic protection of steel structures. However, aluminum has poor mechanical properties and its passivation trend could favor localized degradation in chlorine environment, increasing largely the coating dissolution. In order to improve the sacrificial protection and the mechanical properties provided by the aluminum coatings, several alloying elements have been tested as monolayers, in particular Mo, Mg, and Mn. The use of a single alloying element cannot improve both mechanical and corrosion properties. As a consequence, multilayer configuration appears as a promising solution. Different multilayer configurations have been synthesized associating two elements or alloys: one with good mechanical properties and one with a good sacrificial behavior. This study is focused on the impact of the multilayer configuration on the mechanical and electrochemical properties. Several configurations have been tested: the periodicity Λ was varied between 15 nm and 120 nm. Decrease of the period permits to enhance the corrosion properties of the coatings. The most promising multilayer configuration has been thoroughly investigated. The influence of a plastic deformation on the reactivity was examined. Two different strains have been identified, and the electrochemical behavior of the coating was studied as a function of the strain and compared to pure aluminum.

Progress in Organic Coatings, 2020

Abstract During hygrothermal ageing of organic coatings, water and temperature lead to a coating ... more Abstract During hygrothermal ageing of organic coatings, water and temperature lead to a coating swelling which can be in situ monitored by scanning electrochemical microscopy (SECM). However, it is difficult to separate the respective influence of water and temperature when ageing is performed in aqueous solution. In order to overcome this problem, room temperature ionic liquids can be a solution. In this work, a model DGEBA/DAMP polyepoxide resin, with or without pigments (TiO2) was applied onto steel Q-panels, with a thickness about 100 μm, completely cross-linked, and was aged in a 3 wt.% NaCl aqueous solution. The swelling was measured by SECM for different ageing temperatures in the saline solution. The same epoxy systems were placed in RTIL (1-Ethyl-3-methylimidiazolium ethyl sulfate) and the swelling was measured by SECM at different temperatures. A typical procedure was applied in order to analyze SECM results obtained in RTIL. The results allowed to evaluate the respective contribution of water uptake and temperature to the global coating swelling. The swelling due to temperature was 0.5%/10 °C for unpigmented coatings and 0.3%/10 °C for pigmented coatings while the total swelling was respectively about 5% and 4%, which is higher than the water uptake at saturation. It was then proposed that the swelling excess (about 2% and 1% for unpigmented coating and pigmented coatings respectively) was related to the internal stress relaxation of the polymer network during immersion.

Aerospace Science and Technology, 2017

Abstract The objective of this study was to analyze by three-dimensional finite element method, t... more Abstract The objective of this study was to analyze by three-dimensional finite element method, the effect of the position, number and shape of the bonding defect on the shear stress distribution in the adhesive layer used to joint two aluminum 2024-T3 plates. Numerical analysis allowed us to deduce that the bonding defect presence has a negative effect on the value of the shear stresses in the adhesive layer and therefore the durability of the assembly. Whatever the size of the defect, the maximum stresses are always localized at the adhesive edge. If the overlap length is important, the effect of defect on joint strength is lower.

Progress in Organic Coatings, 2016

Abstract The water sorption characteristics have been determined for two model epoxy systems base... more Abstract The water sorption characteristics have been determined for two model epoxy systems based on the DGEBA resin and two amine hardeners (TETA and DAMP). A particular attention was paid to the curing protocol to control the macromolecular architectures. Using FTIR, DSC and DMTA measurements, it was demonstrated that both network microstructures differ mainly in the polar groups density, the potential crosslinking nodes and the free volume. DGEBA/DAMP system presents a higher free volume fraction and a lower polar groups concentration compared to the DGEBA/TETA system. Gravimetric measurements on free films and EIS experiments onto coated steel Q-panels were carried out to follow the water sorption kinetics at different temperatures (30, 40, 50 and 60 °C). For both epoxy systems, the diffusion processes follow a pseudo-fickian behaviour with two diffusive stages. Solubility and diffusion processes are discussed in relation with the microstructural specificities of the polymer networks using a thermodynamic framework. The main result is that in DGEBA/DAMP and DGEBA/TETA systems, the water diffusion and solubility are mainly governed by a water polar group interaction mechanism.

Journal of Electroanalytical Chemistry, 2014

Electrochimica Acta, 2017

Abstract For many years, the water uptake in organic coatings was measured by EIS and/or gravimet... more Abstract For many years, the water uptake in organic coatings was measured by EIS and/or gravimetry but differences in water content values were found in almost all studies. The Brasher-Kingsbury equation used in the electrochemical analysis (EIS) is often criticized because elementary assumptions may be unvalid. The origin of the discrepancy between both methods is still of interest because many questions remain open and this study aims to provide new insights to these questions. In this work, free films and coatings of a model epoxy-amine system were immersed in a 3 wt.% NaCl solution. The water uptake in free films was evaluated using gravimetric measurements and EIS, using the Basher-Kingsbury equation. The mass of free-films used in the EIS tests was measured and compare to gravimetric measurements while the water uptake (EIS) in free films was compared to that obtained with coatings. It was found that the mass increase of free films tested with EIS was in agreement with gravimetric measurements but was always lower than the water uptake obtained by EIS. Moreover, the water uptake in free films (EIS) was different from that obtained with coatings. In all cases, it was found that the Basher-Kingsbury equation overestimated the water uptake. It appears that the differences between EIS and gravimetric measurements can be analyzed in terms of geometrical effects. Indeed, the swelling in free films and coatings can be monitored by DMA and SECM during ageing. Finally, by mixing the experimental swelling data and the Brasher-Kingsbury equation, the same value of water uptake was obtained by EIS and gravimetry for coatings.

The aim of this study is to perform a finite element analysis of the Von Mises stresses distribut... more The aim of this study is to perform a finite element analysis of the Von Mises stresses distribution in the adhesive layer and of the J-Integral for a damaged plate repaired by a composite patch. Firstly, we study the effect of the fiber orientation, especially the position of the layers that have orientation angle different of 0° from the first layer which is in all cases of our study oriented at (0°) on the J-Integral. Secondly, we evaluate the effects of the mechanical properties of the patch and the use of a hybrid patch on the reduction of stresses distribution and J-Integral. The results show clearly that the stacking sequence for the composite patch must be selected to absorb optimally the stresses from the damaged area and to position the various layers of the composite under the first layer whose fibers orientation will remain in all cases equal to 0°. The use of a hybrid composite reduces significantly the J-Integral and the stresses in both damaged plate and the adhesive ...

Journal of Adhesion Science and Technology

Abstract The effect of an hygrothermal ageing on the mechanical behavior of the bulk adhesive ‘Ad... more Abstract The effect of an hygrothermal ageing on the mechanical behavior of the bulk adhesive ‘Adekit A140 epoxy’ was investigated. The bulk test specimens of the adhesive were immersed in distilled water at various temperatures (20, 40 and 60 °C). Under these conditions, the tensile properties were determined and used in a numerical study about the behavior of bonded assemblies allowing to calculate the J-Integral. The obtained results illustrate the variation of the mechanical behavior of bulk adhesive depending on the immersion time and environmental temperature. The presence of water in the adhesive decreases the tensile strength and the elastic modulus but also increases the ductility of material. These changes in mechanical properties are more important when the percentage of water absorbed increases. The temperature increases the amount of absorbed water in the adhesive, consequently increases the degradation kinetics with the immersion time and directly affect the load transfer rate of the damaged area to the composite patch and therefore the value of the integral J.

Journal of Materials Science

AbstractThis study focused on the influence of a pigment (titanium dioxide at rates of 10 and 20 ... more AbstractThis study focused on the influence of a pigment (titanium dioxide at rates of 10 and 20 wt%) on the hygrothermal ageing of a model epoxy polymer resin (DGEBA–DAMP). An ageing cycle composed of sorption and desorption steps was applied at different temperatures. Gravimetric study was carried out on free films. Results of pigmented samples were compared with those of the resin alone to better understand impact of the titanium dioxide. TiO2 had no major influence on gravimetric curves: water content curves exhibited a pseudo-Fickian behaviour during sorption and Fickian one during desorption. Moreover, results pointed out that pigment did not absorb water. Curve treatment allowed to obtain diffusion coefficient and water content at equilibrium for each step of ageing. Values of diffusion coefficients indicated that titanium dioxide did not have major influence on the beginning of diffusion, whereas it slowed down the end of water uptake. During sorption, water content at equilibrium was dependent on TiO2 amount. After desorption, pigmented systems contained residual water for ageing cycles at high temperature. Finally, results of diffusion coefficients showed that diffusion phenomena were heat dependent. A thermodynamic approach was then used to have access to enthalpy of diffusion ΔH and pre-exponential factor D0. These parameters were impacted by the presence of titanium dioxide. This was mainly due to the presence of additional internal stresses of Type II.

Aerospace Science and Technology

Abstract The objective of this study is to analyze by experimental tests, the effect of hygrother... more Abstract The objective of this study is to analyze by experimental tests, the effect of hygrothermal aging of the patch and the adhesive on the fatigue behavior of a damaged 2024-T3 aluminum plate repaired by a carbon/epoxy patch composite. The effect of the water absorption by the composite patch and the adhesive has a significant effect on the load transfer from the damaged plate and therefore on the delay of the crack propagation. The more water immersion time is important, the less is the fatigue strength of the repaired structure. The experimental results showed that the number of cycles to fracture is directly related to the aging time.

Aerospace Science and Technology

Abstract In this paper, we analyze the variation of shear stresses in the adhesive layer, used in... more Abstract In this paper, we analyze the variation of shear stresses in the adhesive layer, used in a single lap joint, in the presence of variable numbers and positions of defects. The results of the value of maximal shear stresses were used to develop a shear stress probability distribution models in the adhesive of SLJ with presence of one, ten and fifty defects with random position to improve the damage probability. Based on the result found in part-I [1] , a set of theoretical samples was generated and their corresponding histograms using Freedman–Diaconis method. Seven different probability density functions (PDFs) were fitted to these histograms. In each case, a Kolmogorov–Smirnov test was used to evaluate the quality of fit. Finally, after substituting the values of estimated parameters for each distribution, a set of fully defined PDFs have been proposed for the shear stress in the adhesive layer of SLJ in the presence of artificial defects with random positions. This PDF has been used to introduce a new criterion included critical shear stress but also distribution parameters of damage.

Structural Engineering and Mechanics

Surface and Coatings Technology

Progress in Organic Coatings, 2007

A zinc-rich powder coating, applied onto steel substrate, was studied using electrochemical imped... more A zinc-rich powder coating, applied onto steel substrate, was studied using electrochemical impedance spectroscopy (EIS). Before immersion when coating is dry, EIS spectra revealed that the percolation threshold was reached. Then, an equivalent circuit including a transmission line was applied to model electrochemical response. In this model, which considers isolated and semi-isolated zinc particles within the binder, it was found that both phases were equally distributed in the coating.

Journal of Adhesion Science and Technology, 2006

ABSTRACT

Electrochimica Acta, 2008

In this work, hydrochloride polyaniline (PANI-Cl) powder was incorporated as a conductive pigment... more In this work, hydrochloride polyaniline (PANI-Cl) powder was incorporated as a conductive pigment into powder zinc-rich primer (ZRP) formulations in order to enhance the electronic conduction paths between zinc particles inside the coating and the steel substrate (i.e. percolation). Coatings were applied onto steel substrates and immersed in a 3% NaCl solution at ambient temperature.

Applied Surface Science, 2014

ABSTRACT In France, hot water quality control inside buildings is occasionally ensured by disinfe... more ABSTRACT In France, hot water quality control inside buildings is occasionally ensured by disinfection treatments using temperature increases or addition of sodium hypochlorite (between 0.5 ppm and 1 ppm residual free chlorine). This disinfectant is a strong oxidiser and it could interact with metallic pipes usually used in hot water systems. This work deals with the study of the impact of these treatments on the durability of copper pipes. The objective of this work was to investigate the influence of sodium hypochlorite concentration and temperature on the copper corrosion mechanism. Copper samples were tested under dynamic and static conditions of ageing with sodium hypochlorite solutions ranging from 0 to 100 ppm with temperature at 50 degrees C and 70 degrees C. The efficiency of a corrosion inhibitor was investigated in dynamic conditions. Visual observations and analytical analyses of the internal surface of samples was studied at different ageing duration. Corrosion products were characterised by X-ray diffraction and Raman spectroscopy. Temperature and disinfectant were found to considerably affect the copper corrosion mechanism. Surprisingly, the corrosiveness of the solution was higher at lower temperatures. The temperature influences the nature of corrosion products. The protection efficiency is then strongly depend on the nature of the corrosion products formed at the surface of copper samples exposed to the aggressive solutions containing different concentration of disinfectant.

Materials Science Forum, 1998

The effect of addition of conductive pigments like carbon blacks on the corrosion behavior of zin... more The effect of addition of conductive pigments like carbon blacks on the corrosion behavior of zinc-rich powder paints coated steel in artificial sea water was investigated. Open circuit potential measurements were used to characterize the cathodic protection ability and duration. Micro-Raman spectroscopy analysis was performed in order to identify the corrosion products and to follow the penetration of the solution inside the coatings.