Liste des publications
Probabilistic analysis of corroded pipeline under localizedcorrosion defects based on the intelligent inspection tool
A methodology is developed in this paper to estimate the time-dependent reliability of a pipeline in Algeria, which is in exploitation from 1981 and with internal and external localized corrosiondefects detected in 2009. A probabilistic approach was applied to a pipeline made of API 5L X60steel for the long-distance transportation of natural gas (55 km), which crossing several geographical reliefs in different country areas. The analysis was carried out by taking into consideration the potential stochastic variables altering drastically the reliability of the pipeline, i.e.,dimensions of the localized corrosion defects, their locations, and distribution, and the corrosionrate. The correlations between the pipeline spatial corrosion defects distribution and their dimensions, obtained by using an intelligent inspection tool are used to analyze the actual inservice corrosion attack rate and for enhancement of the accuracy of the reliability assessment.The failure scenario was considered as the moment when the pipeline operating pressure exceedsthe failure pressure defined analytically in accordance with different commonly used standards.The assessment of the reliability index of the corroded pipeline subjected to internal pressure andthe failure probability was done. The detailed reliability analysis is carried out by using thesecond order reliability method (SORM) for the basic random variables with different probabilistic density within a nonlinear limit state function. The latter is based on the limit analysis ofthe failure pressure model for different standards and the numerical analysis using the finiteelement method and ANSYS software. Voir les détails
Mots clés : Reliability, corrosion, Inspection, FEM
Study of The Structure and Corrosion Behavior of Al-15%MoAlloy
The influence of the addition of molybdenum on the structure and corrosion behaviour of aluminium was studied using optical microscopy, scanning electron microscope (SEM),potentiodynamic polarization and electrochemical impedance spectroscopy. The results showthat the addition of 15%wt molybdenum causes the precipitation of the Al12Mo intermetallic phase which appears in plate form on the αAl matrix. The results of the electrochemical tests show that the addition of molybdenum displaces the corrosion potential of aluminium towards positive values from -699 mV/ECS to -633 mV/ECS and increases the charge transfer resistance from to 4752 Ω.cm2 to 6608 Ω.cm2. Voir les détails
Mots clés : corrosion, Al-15%MoAlloy, Electrochemical behavior
Effect of Heat Treatment on the Structure, Wear and Corrosionof AISI L6 Tool Steel
This work is a contribution in analyzing structure, tribological behavior and corrosion ofAISI L6 hardened tool steel. Structural characterization and tribological behavior of steel wereinvestigated using Optical Microscopy (OM), Scanning electron microscopy (SEM), wear testing byfriction on a pin-on-disc Tribometer and corrosion by potentiodynamic polarization. Comparing tothe as-received steel, hardening has generated a fine martensitic microstructure causing a 1.5 timeshardness increase. Hardening has contributed to improvement of wear resistance as the coefficient offriction has decreased from 0.86 to 0.67μ. An increase in corrosion resistance was observed afterhardening treatment. Voir les détails
Mots clés : tool steel, AISI L6, friction, hardening, corrosion, heat treatment, wear
Synthesis and tribocorrosion performances of multilayer (Ta/ZrN)n coatings
Multilayer thin coatings (~3 µm in thickness) were deposited using reactive radio frequency magnetron sputteringon Ti-6Al-4 V substrate for biomaterial applications. Films are a combination of hard zirconium nitride with pure tantalum, used to manage interfacial stress and to avoid crack growth. Alternating hard/ductile material is a biomimetic design inspired by nature(nacre-inspired materials). Tribocorrosion tests were performed in Hank’s solution at 37 C, under open circuit potential by using a ball-on-disk reciprocating tribometer. A tendency to high resistance against corrosion was found for all the samples. Coatings with a top 100 nm thick ZrN layer showed more noble potential as well as a reduction of both the friction coefficient and the wear rate during the sliding phase. The principal wear mechanism is related to a tribocorrosion layer formation. Voir les détails
Mots clés : Multilayer coating, Biomaterial, Tribocorrosion, Tantalum, Zirconium nitride, Magnetron sputtering
Mechanical properties and bio‑tribological performance of PVD (Ta/ZrN)n multilayer coatings on UHMWPE in bovine serum lubrication
This work investigated the tribological performance of (Ta/ZrN)n multilayer coatings against ultrahigh molecular weight polyethylene (UHMWPE) material. Three multilayer coatings with different designs were deposited on Ti-6Al-4V substrate and subjected to wear testing under lubrication of diluted bovine calf serum. The results revealed an improvement in wear resistance of (Ta/ZrN) multilayer coatings and low coefficient of friction under an applied load of 1 N. High hardness, excellent biotribological properties, and low residual stresses were obtained in the multilayer coating with the thinnest ZrN as the topmost layer of 100 nm. This work demonstrates that Ta/ZrN multilayers can be promising coatings for prosthesis applications. Voir les détails
Mots clés : PVD coating, Ta/ZrN, UHMWPE, wear
Surface peformances of PVD ZrN coatings in biological environments
Zirconium nitride (ZrN) thin films were deposited by reactive RF magnetron sputtering on Ti-6Al-4V and Si (100) substrates for potential use in biomedical applications. The tribological behaviour was evaluated against bovine bone in dry condition using a pin-on-disc apparatus. Abrasion is the primary wear mechanism observed in ZrN/bone contact. The corrosion properties were determined through two electrochemical techniques: potentiodynamic polarization and electrochemical impedance spectroscopy. The coatings with reduced oxygen content provided: (i) good resistance against corrosion when exposed to physiological solution and (ii) better anti-bioadhesion against Staphylococcus aureus bacteria. Voir les détails
Mots clés : PVD coating, ZrN, wear, corrosion, bioadhesion
Inhibition Effect of 2,2’-bipyridyl on the Corrosion of austenitic Stainless Steel in 0.5M H2 SO4
The corrosion inhibition of AISI309 austenitic stainless steel by 2,2'-Bipyridyl in 0.5MH2SO4 at 298K was studied using the mass loss’ method, the potentiodynamic polarization (Tafel), the linear polarization (LRP), and the electrochemical impedance spectroscopy (EIS). The results showed a mixed inhibition mode and an increase in the charge transfer resistance, due to inhibitor molecules adsorption at steel surface. This latter obeys to Langmuir isotherm. The observation by scanning electron microscopy (SEM) and the analysis by energy dispersion spectrometry(EDS) confirm an inhibitor film’s presence. The calculated inhibition efficiencies are in accordance with 87.78% maximum value. Voir les détails
Mots clés : AISI309, 2, 2'-Bipyridyl, corrosion, EIS, Tafel
Tribocorrosion Dependence on Porosity of TiNi Alloysin Phosphate‑Buffered Saline Solution
Degradations of implants during their service life lead to rejection because of corrosion and wear-related problems, i.e., toxicions and wear particles released into the human body. In this case, tribocorrosion tests are appropriate ways to investigate thesynergistic effect of the corrosion and wear phenomena, on the material implant in simulated body fluids. This study aims toanalyze the bio-tribology as well as the tribocorrosion performances of porous TiNi alloys, fabricated from elemental powdermixture (Ti, Ni) by powder metallurgy. The effect of the level in porosity, resulting from four (04) different cold pressing, wasinvestigated against alumina ball in phosphate-buffered saline solution (PBS) at 37 °C. SEM/EDS microstructural analysesrevealed the presence of various phases with TiNi as the predominant phase. Obtained results showed that the lowest frictioncoefficient was recorded for the sample with 33% in porosity rate when sliding against an alumina ball in dry conditions. Ahigh tribocorrosion resistance for all the studied TiNi compositions was also observed. Based on the corrosion parametersand the wear rate, the composition with the highest porosity exhibited the optimum performance. Voir les détails
Mots clés : TiNi alloys, Biotribolgy, Tribocorrosion, Porosity
Effect of erosion parameters on the surface direction texture-Study by experimental plans
The aim of this work is to study the effect of solid particle impact erosion parameters of sand on the isotropy parameter "Std" which presents the direction of surface texture. The experimental methodology adopted for this experimental work is the Box Behnken plan with three factors, each at three levels (-1, 0 and +1), the parameters considered are: time "t", pressure "P" and angle of impact "θ". 3D roughness measurements were carried out using a laser source profilometer type Cyper-Technologie-CT100, in order to characterize the different surfaces after erosion test. The statistical analysis was carried out using the Mini Tab software, where a mathematical model was established showing the relationship between the input parameters (t, P, θ) and the output parameter "Std". This model predicts the "Std" response in the field of study as well as the parameters of the sandblasting regime. The results show the significant effect of the impact angle on "Std" and the interaction between the different parameters in the study domain, of which the highest value of "Std" is equal to 130 ° for an average time combined with low pressure and impact angle. Voir les détails
Mots clés : erosion, topography, roughness surface, Mathematical model, Box plans
Influence of dry friction on the wear behavior of X52steel—experimental study and simulation using response surfacesmethod
Friction and wear phenomena alter the behavior of the material surface, where certain relevant parameters which characterizethe surface are influenced. Therefore, the objective of this work is to identify the parameters most influencing the frictioncoefficient (f), the wear rate (Ws), and the volume parameters (Vmc and Vvv) during the friction test. The friction tests werecarried out by adopting the methodology of 23complete planes with three factors (D, V, and Py), at two levels each. Theresults show a decrease in the wear rate when all three factors are at their highest level and a decrease in the friction coefficientwhen using minimum load on speed long distances. In addition, the mathematical models developed allow to reveala correlation between the test parameters (D, V, and Py), and the responses studied (f, Ws) in their study field. Moreover,the volume parameters Vmc and Vvv were evaluated during the tests, and the morphology of the worn surface shows thatthe friction under a load of 1 N leads to the predominance of an abrasive wear mechanism, while a load of 10 N promotesan adhesive wear mechanism. Voir les détails
Mots clés : Complete plans, modeling, friction coefficient, Wear rate, volume parameters