Iost Alain

• Professor Emerite
• Professor Emeritus at Ecole Nationale Supérieure d'Arts et Métiers LILLE

The main objective of this paper is to compare the fracture toughness determined by instrumented indentation tests of a variety of self-compacting concretes (SCCs) and normal vibrated concretes (NVCs). For this purpose, five mixing compositions of self-compacting concrete (SCC) with different water/binder ratios of 0.33 to 0.41 (water/cement ratio...

Nanoindentation is a technique commonly used to measure the mechanical properties of thin films even at depths less than 1 μ m. In fact, the characterization is based on the study of the load/displacement curves resulting from the nanoindentation test. We aim to use the backtracking search optimization algorithm (BSA) to improve the extraction of P...

Instrumented indentation testing is widely used to determine the mechanical properties of materials. In particular, this technique makes it possible to study brittle materials for which cracks can be generated around the impression during the indentation test. Cracking can result in the formation of pop-ins on the curve load-segment which can be us...

Replacement of toxic and expensive vanadium (V) in medical grade titanium alloys with cheaper and non-toxic elements such as iron (Fe) or niobium (Nb), is an important step forward in developing safer and less expensive biomaterials. Evaluating the effect of different process parameters such as the milling time on the properties of these newly deve...

Carbon black (CB) filled elastomers are structurally complex materials that offer unique properties at different length scales. They have tremendous potential applications in a number of fields including the automotive and aerospace industries and for designing innovative smart materials such as artificial muscles but their applications remain limi...

Surfactants are widely used in many chemical industries and as primary components of cleaning detergents due to their specific characteristics,which in turn results in high pollution of domestic and industrialwastewaters by such substances. In this study, the mechanistic pathways of the adsorption of cationic benzyl-dimethyl-dodecyl ammoniumbromide...

Implant-related follow up complications resulting from poor implant integration, delamination, chipping, mechanical instability, inflammation or graft-vs-host reaction may lead to low patient tolerance, prolonged care and sometimes leading to a second surgery. Hence, there is an urgent need for developing biomaterials which will help to overcome th...

In this study, an attempt is made to quantify the brittleness in semicrystalline ethylene-co-butyl acrylate copolymer samples reinforced by carbon black (CB) nanoparticles. A series of samples with different CB volume fractions are investigated at ambient conditions. Two approaches are used to quantify the brittleness parameter. On the one hand, we...

This investigation addresses the effect provided by industrial surface finishes on the tribocorrosion properties of 316L stainless steel exposed to NaCl solution. Three distinct surface treatments were evaluated: passivation (SSO), electropolishing-passivation (SSEP) and micro-undulation (SSM mechano-chemical + electropolishing + passivation). For...

The wear behaviour of the TiNi alloy tested at different conditions (2 and 4 N as applied loads and 40, 50 an 60 wt % as nickel contents) was investigated. For this purpose, two main experimental techniques consisting of wear and indentation tests were used. Scanning electron microscopy (SEM) and laser source profilometry were employed to reveal th...

Ti–Ni powder compacts were prepared by Mechanical alloying (MA), followed by hot isostatic pressing (HIP). Afterwards, the samples were sintered at different temperatures (950, 1050, 1150 and 1250 °C). Microhardness, density, crystallite size as well as microstrain of the sintered samples were measured and analyzed. Wear characteristics in phosphat...

Hexavalent chromium pollution from industrial waste water is a serious problem as it can cause adverse effects on the environment. Several methods are used to reduce the harmful effects of this pollutant, especially physico-chemical methods, such as Adsorption technology. The present study Preparation of Cr (VI) solution) from industrial sources in...

The effect of sintering temperature (1073−1373 K) on the structural and tribological properties of nanostructured ball- milled β-type Ti−15Mo samples was investigated. The prepared samples were characterized using various apperatus such as X-ray diffractometer, scanning electron microscope (SEM) and ball-on-plate type oscillating tribometer. Wear t...

Low modulus β-type Ti-15Nb alloys were prepared by subjecting them to different sintering temperatures (800, 900, 1000 and 1100 °C) and their morphological and structural properties were evaluated. X-ray diffraction analysis was used for the morphological characterization which indicated that the mean pore and crystallite size continuously decrease...

Low modulus β-type Ti-15Nb alloys were prepared by subjecting them to different sintering temperatures (800, 900, 1000 and 1100 °C) and their morphological and structural properties were evaluated. X-ray diffraction analysis was used for the morphological characterization which indicated that the mean pore and crystallite size continuously decrease...

Determination of hardness profiles of Functionally Graded Materials could be currently performed by two principal methods. One method consists in the measurement of hardness on the cut cross-section of the sample, which is destructive, expensive and time consuming. Another method involves the measurement of hardness at the surface with increasing l...

The resistance to separation of the concrete from its reinforcing steel with which it is in contact is called adhesion .This adhesion constitutes an important property for the use of reinforced concrete. That is why many techniques were developed with the aim of determining this property. Adhesion can be easily found out by standard pullout test ma...

The bio-tribocorrosion behavior of newly developed near β-types Ti-15Nb and Ti-15Mo alloys was investigated in Phosphate-Buffered Saline (PBS) under different loads. Open-Circuit Potential (OCP), friction coefficient, wear volume and wear rate were evaluated. The results revealed that Ti-15Nb alloy exhibited lower wear rate, lower friction coeffici...

The hydrophilic-hydrophobic surface area of alumina powder (Al2O3) oxidized at different temperatures was determined on the base of adsorption of water and butane vapor at 25°C. In the order to study the influence of thermal oxidation upon hydrophilic/hydrophobic character of the surface, samples of Al2O3 were characterized using granulometry, SEM...

Aiming to develop alloys with better properties for orthopedic applications, the focus of the present research was to evaluate the effect of Mo at.% content on structural, mechanical, and tribological properties of hot isostatically pressed Ti-xMo (x = 4, 8, 12, 15, and 20 at.%) alloys. The structural evolution, mechanical properties, and tribologi...

The aim of this study was to investigate the influence of thermo-cyclic treatments on the mechanical characteristics (Hardness and Resilience) of low-alloy 42CD4 steel. Thermocyclic treatment on 42CD4 steel was operated for four cycles at 850 °C for 30 min. After each cycle, the steel sample was cooled in different medium (open air and water) in or...

The basis of the virtual machine concept, which is commonly used in coordinate measuring machines, was implemented to determine more realistic uncertainties on the estimation of the elastic modulus obtained from nanoindentation tests. The methodology is based on a mathematical model applied to simulate the testing process and to evaluate the uncert...

In this paper, the mechanical properties, the creep and the tribological behaviours of three borided and non-borided steel materials were analysed. The alloy steel substrates were borided by a powderpack boriding process during 8 h at 950 °C. The creep process during the holding stage of nanoindentation test was analysed using various mathematical...

Mechanical properties of heterogeneous systems based on carbon black (CB) filled semi‐crystalline ethylene butyl acrylate (EBA) copolymer nanocomposites are characterized using nano‐indentation technique. The size effect and CB content dependence on the deformation behavior at room temperature were investigated. The phenomenology for hardness respo...

Cracking resistance or fracture toughness of brittle materials, such as optical glasses, can be determined by Vickers indentation, which allows generating cracks along the diagonals of the indent whose length depends of the loading rate. Subsequently, a relationship between the crack length and the corresponding indentation load is applied to calcu...

This work is focused on the mechanical characterization by multiscale indentation (nano and macro) of a brake pad material, with multiple phases and complex microstructure for applications in the railway industry. Grid nanoindentation tests allowed to identify the mechanical properties of the components in the formulation. The significant differenc...

Deux revêtements à base nickel obtenus par des bains réducteurs, l’un brut et l’autre ayant subi un traitement thermique sont étudiés. L’essai d’indentation a été mis en œuvre pour caractériser la dureté et le module de Young de ces dépôts. Les résultats montrent une bonne homogénéité des propriétés mécaniques dans l’épaisseur du revêtement, alors...

The focus of the present research is to evaluate the friction and wear behavior of two biomaterials alloys for total hip prostheses use, SSAISI 316L and a+b type titaniumalloy (Ti-6Al-7Nb).A ball on-disk tribometer (TRIBOtester) was used for tribological tests under wet condition using physiological solution (Hank’s solution) according to the ASTM...

The focus of the present research is to evaluate the friction and wear behavior of two biomaterials alloys for total hip prostheses use, SS AISI 316L and α + β type titanium alloy (Ti-6Al-7Nb). A ball-on-disk tribometer (TRIBOtester) was used for tribological tests under wet condition using physiological solution (Hank’s solution) according to the...

The aim of this work is to investigate the tribological behaviour of a continuous hot dip galvanized steel. This paper presents a fundamental study of the characteristics of zinc coating in terms of morphology, surface roughness and tribological behavior according to process parameters typical of industrial processes continuous galvanization. The m...

Galvanization-morphologie structurale--nanoindentation des couches galvanisées-comportement tribologique

Resumen Las propiedades de los recubrimientos a base de circonia estabilizada con ytria (YSZ) confieren a estos un excelente desempeño en una amplia gama de aplicaciones que van desde el uso odontológico hasta barreras térmicas, incluyendo también su empleo como electrolitos sólidos en celdas de combustible. En el presente trabajo, se depositaron r...

Coatings based on WC–12Co, with and without the reinforcement of carbon nanotubes (CNTs) have been deposited by means of the HVOF thermal spraying technique on a SAE 1020 steel substrate. The aim of the present study is to evaluate in detail the influence of the 36 h milling time on both feedstock powders, particularly on the mechanical properties...

Nanostructured Cr-Al-N thin film with different Al content (0 to 50 at.%) were deposited. The structural evolution and morphological changes were performed. The tribological performances were evaluated using a ball-on-disk type Oscillating tribometer. The tests were carried out under normal loads of 2, 10 and 20 N respectively. The results showed t...

In the present study, the effect of thermal treatment on the mechanical and structural properties of chromium carbide coatings with different thicknesses is evaluated. The coatings were deposited by cathodic magnetron sputtering on XC100 steel substrates. Samples were annealed in vacuum, at different temperatures ranging from 700 to 1000°C for 1 h,...

The interfacial indentation test is experimented for the first time in order to characterize the adhesion between the concrete and its steel reinforcement. This technique, developed to estimate the adhesion of thick coatings (thermal barrier, plasma torch deposits, etc.), is used here to create and propagate a crack along the concrete/reinforcement...

The present work has been conducted in order to assess the mechanical and tribological performance of a ZrN/Mo2N coating deposited onto a H13 steel by means of a closed field unbalanced magnetron-sputtering ion-plating process. The hardness and elastic modulus of the coated system have been determined employing nanoindentation techniques. Dry and w...

Nanostructured Cr-Zr-N thin film with different Zr content (0 to 48.8 at.%) were deposited using an RF magnetron sputtering technique. The structural evolution and morphological changes were performed. The tribological performances were evaluated using a ball-on-disk type Oscillating tribometer. The tests were carried out under normal loads of 2, 4...

A study of mechanical properties of mesoporous silicon (PS) is presented in this article. PS was prepared by electrochemical etching of a heavily doped P⁺⁺ silicon wafer in a hydrofluoric acid electrolyte. The mechanical properties of PS and oxidized PS obtained by thermal treatment, were characterized by the nanoindentation technique associated to...

The assessment of mechanical properties of materials by instrumented indentation tests have been widely performed in last years. The objective of this work was to develop a methodology to analyze the mechanical behavior of materials from the data obtained by a continuous multicycle indentation test at the microscale of loads to limit the problems a...

This study aims to examine the effect of replacing vanadium by niobium and iron on the tribological behavior of hot-isostatic-pressed titanium alloy (Ti–6Al–4V) biomaterial, using a ball-on-disk-type oscillating tribometer, under wet conditions using physiological solution in accordance with the ISO7148 standards. The tests were carried out under a...

Binary Cr-N, Zr-N and Cr-Zr-N films were synthesised using a R.F. reactive magnetron sputtering technique by co-sputtering Cr and Zr. The crystalline structure, morphology, mechanical and tribological properties of the films as a function of Zr content were characterised by X-ray diffraction, microanalysis X (WDS, EDS), X-ray photoelectron spectros...

Cr–Zr–N films have been synthesised using R.F reactive magnetron sputtering system on Si (100) wafer and XC100 steel substrate without heating. The structural, mechanical and friction coefficient evolution as a function of the Zr content were investigated by XRD, (EDS, WDS), WPS, XPS, SEM, AFM, nanoindentation, Scratch adhesion and pin-on-disc slid...

L’essai d’indentation instrumentée est une technique très utilisée car elle permet d’estimer les propriétés mécaniques des matériaux comme la dureté et le module de Young. Cette étude sur l’indentation multi-échelles (de 5 mN à 2 kN) a été réalisée sur des matériaux métalliques massifs (acier, acier inoxydable et aluminium) avec trois instruments :...

In the literature, the most studies conducted on the flat surface ball-burnishing process have been focused on the most important classical factors like burnishing speed, lateral feed, and the ball-burnishing load or pressure on the treated surfaces integrity enhancement. In this research, ball-burnishing strategies are studied as a new ball-burnis...

The unloading part of a load–displacement curve from instrumented indentation tests is usually approximated by a power law (Oliver and Pharr model), where the load is the dependent variable. This approach generally fits well the data. Nevertheless, the convergence is occasionally quite questionable. In this regard, we propose a different approach f...

The aim of this research paper is to fabricate a Fe-TiC composite by a novel and simple manufacturing method. The latter is based on two cumulative processes; a conventional sintering (transient liquid phase sintering) and a hot forging with steam hammer respectively. The blinder phase of the studied simples is varied from carbon steel to high allo...

In this work, nano, micro, and macro-indentation tests under standard or multicycle loading conditions were performed for studying the mechanical behavior of a crown borosilicate glass sample with the objective to study the scale effect in indentation and the influence of cracks formation on the assessment of mechanical properties. When no cracks w...

In this work, a new ball-burnishing strategy, in two crossed passes, was applied on the flat machined surface of 2017A-T451 aluminum alloy to investigate the influence of three classical ball-burnishing factors (burnishing speed V b in mm/min, depth of penetration a b in μm and lateral feed f in mm) on the treated surface integrity enhancement. Exp...

Solid phase sintering of elemental titanium and nickel powders was used to process the porous TiNi alloy. In this work, the effect of the sintering temperature on the mechanical, tribological and electrochemical behavior of this alloy was studied. Analysis by X-ray diffraction, scanning electron microscopy (SEM) and EDS analysis reveal the formatio...

In this investigation, the mechanical properties of the different layers composing a CuIn1 − xGaxSe2 (CIGS) based solar cell were studied. Magnetron sputtering technique was used for the deposition of these layers except for the cadmium sulphide (CdS) layer which was deposited using chemical bath deposition process. We performed several indentation...

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CHARACTERIZATION OF MATERILAS PROPERTIES NANOCOMPOSITES

Numerous methods have been proposed to estimate the indentation fracture toughness Kic for brittle materials. These methods generally uses formulæ established from empirical correlations between critical applied force, or average crack length, and classical fracture mechanics tests. This study compares several models of fracture toughness calculati...

In a previous investigation (Bigerelle and Iost, 2004), the authors have proposed a physical interpretation of the instability λ = Δt/Δx² > 1/2 of the parabolic partial differential equations when solved by finite differences. However, our results were obtained using integration techniques based on erf functions meaning that no statistical fluctuat...

The results of the mechanical and tribological characterization of a prototype a-C:Cr, Si sputtered coating are presented. The hardness and the elastic modulus of the coated system have been determined by means of nanoindentation taking into account the actual architecture of the bi-layer coating. Both mechanical properties were recorded continuous...

During the last past decades, galvanised steels have been extensively developed to improve corrosion resistance of steels due to their excellent chemical properties particularly in severe atmospheric conditions. The objective of this work is to predict the hardness-load variation in relation to the bath immersion time using both a m ultilayer coati...

The mechanical property determination of thin films by nanoindentation can be affected by the substrate depending on the indentation testing conditions and the film thickness. In this condition and especially for very thin films, application of models is required for separating the substrate influence of the indentation measurement. In this paper,...

Considerable improvement in the tribological response was achieved during sliding wear tests against alumina ball, when AA 2024-T3-aluminium alloy substrate was coated with DLC/NiP duplex coating. Quantitative EPMA analysis carried out on the coated sample cross-section coupled with nanoindentation techniques allowed the identification of the coate...

The evaluation of the elastic response of coated systems under indentation loading represents a crucial issue, which determines the behavior of such systems under tribological applications. Although a number of models have been proposed in the literature for the description of the change in the composite modulus with indentation depth, as well as f...

This paper presents an experimental study of the tribological behaviour of a multimaterial system using conventional powder metallurgy process with SiO 2 nanoparticles. Four configurations were studied with and without SiO 2. The tribological properties of the sintered materials were analysed by wear experiments at lubricated conditions on a ball d...

The purpose of this paper is to analyze the turning machinability of a martensitic steel, according to the cutting speed, and through signal analyses of the morphology of the machined surface. We initially carried out the classification of a large number of parameters of roughness, on the basis of their relevance with regard to cutting speed. The o...

The change in the composite hardness with penetration depth derived from nanoindentation tests conducted on coated systems, which involve the deposition of multilayer coatings, in general exhibit a complex shape, as a consequence of the sequential contribution of each coating layer to the composite hardness during indentation loading. In spite that...

Les propriétés mécaniques des films minces sont généralement déterminées par nanoindentation pour éviter l’influence du substrat. En effet, nous savons que le substrat influence cette mesure dès lors que l’indenteur pénètre à plus de 10 % de l’épaisseur du film pour la dureté, ce chiffre pouvant être ramené à 1 % pour le module d’élasticité. Pour d...

Comparative study by indentation test of the mechanical characteristics of sodalimeand ceramic glasses ground and polished by bound abrasive grains. In this work, indentation toughness of 4 optical glasses (Crown K5, Heavy flint, Float glass and Zerodur r) was analyzed regarding its surface quality. Despite the large number of the involved technolo...

The present research was carried out with the aim of studying the influence of oxygen concentration during processing on the properties of the VOx coatings deposited by cathodic magnetron sputtering on a stainless steel AISI 316L substrate. Mechanical and tribological properties were measured by nanoindentation and sliding wear tests respectively....

In this work we present our recent investigation on characterizing mechanical properties of porous silicon (PS) by using instrumented micro-indentation. Hardness and elastic modulus for oxidized and nonoxidized PS were measured. Experimental results revealed that hardness and elastic modulus are significantly lower than that of silicon substrate an...

Nanostructured yttria-stabilized zirconia coatings for applications in high-temperature environments can be deposited by suspension plasma spraying (SPS) techniques. The present research has been conducted in order to study the sliding wear response of a SPS ZrO2–8% mol. Y2O3 coating (75 μm in thickness) deposited onto a Haynes 230 substrate, using...

A novel method is developed to improve the accuracy in determining the mechanical properties from nanoindentation curves. The key point of this method is the simultaneous statistical treatment of several loading curves to correct the zero point error and identify the material properties considering size effects. The method is applied to four sandbl...

CrSiN films were deposited by reactive radio frequency magnetron sputtering in an Ar+N2 gas mixture. The nitrogen gas was injected in the deposition chamber using two methods: the classical constant injection and pulsed injection, the latter known as the reactive gas pulsing process (RGPP). Argon gas was continuously injected, whereas nitrogen gas...

The aim of the study is to evaluate the friction and wear behavior of high-strength alloys Ti-6Al-7Nb used in femoral stem and compare it with a Ti-6Al-4V alloy cylindrical bar corresponding to ISO 5832-3 part 3/01-07-199 standard. The tribological behavior was investigated by wear tests, using ball-on-disc and pin-on-disc tribometers. These tests...

In nanoindentation, especially at very low indenter displacements, the indenter/material contact area must be defined in the best possible way in order to accurately determine the mechanical properties of the material. One of the best methodologies for the computation of the contact area has been proposed by Oliver and Pharr [W.C. Oliver, G.M. Phar...

The goal of this paper is to study the main uses of the residual imprint of the indentation test. It also discusses the different technologies and methods employed in this context. The difficulties encountered when trying to exploit the full potentials of the imprint are thoroughly examined. A survey of the literature on the quantification of the p...

A quantitative model is proposed for the estimation of macro-hardness using nanoindentation tests. It decreases the effect of errors related to the non-reproducibility of the nanoindentation test on calculations of macro-hardness by taking into account the indentation size effect and the surface roughness. The most innovative feature of this model...

Tribological behavior of biomaterials AISI 316L and Ti-6Al-7Nb was investigated by wear tests, using tribometers ball on disc and sphere on plane. These tests consisted of measuring the volumetric wear and the friction coefficient. Tribological tests have been carried out in ambient air with oscillating tribotester in accord with standards ISO 7148...

The aim of this research is to study the tribological behavior of Ceramic for Surgical Implants (Total hip prosthesis). The tribological behavior is evaluated by a wear tests, using Tribometres ball - on -disc and sphere - on - plane. These tests consisted of measuring the weight loss, and the friction coefficient of ceramic. The Oscillating fricti...

Friction and wear plays an important role in determining the performance of biomaterials. To this end, the present research is carried out to understand the tribological behavior important biometallic alloy, Ti-6Al-4V under sliding contact. The friction and wear experiments were carried out using ball-on-disc and pin-on-disc tribometers in ambient...

The aim of this research is to study the tribological behaviour of AISI 316L bare supplied by LML ENSAM LILLE and compared it with a surgical Implants AISI 316L as Total hip prosthesis ( femoral steam) The tribological behavior is evaluated by a wear tests, using Tribometres ball on disc and sphere on plane. These tests consisted of measuring the w...

Tribological behavior of biomaterials AISI 316L and Ti-6Al-7Nb was investigated by wear tests, using tribometers ball on disc and sphere on plane. These tests consisted of measuring the volumetric wear and the friction coefficient. Tribological tests have been carried out in ambient air with oscillating tribotester in accord with standards ISO 7148...

The authors wish to thank the participating communities, the Laboratory of Mechanics surfaces and materials processing, University Lille for the access and 84 usage of its research facility. Present research is financially sponsored by Found for Scientific Research of the Flemish Community (FWO) and the Ghent University Research Board.