LGeCo LISS

Portvendres, France

LGeCo LISS

Portvendres, France

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Garcia-Alonso D.,University of Technology of Belfort - Montbéliard | Serres N.,LGeCO LISS | Demian C.,University of Technology of Belfort - Montbéliard | Demian C.,University of Burgundy | And 4 more authors.
Journal of Thermal Spray Technology | Year: 2011

Lasers have been used to improve the ultimate performance of thermal spray coatings for specific applications, but the full potential of additional laser treatments must be further explored. Laser treatments (auxiliary processes) can be applied before, during or after thermal spraying (main process), leading to a wide range of coating improvements (microstructure, adhesion, etc.). The aim of this review is to introduce the most significant laser treatments for thermal spray applications. The potential improvements for thermal spray coatings are illustrated by a selection of representative research cases. Laser pretreatments (ablation and texturing) promote coating/substrate adhesion and are suitable to prepare the surface of sensitive substrates such as aluminum, titanium, or magnesium alloys. The use of these techniques, which leads to several benefits such as surfaces free of grit-particle inclusions, directly improves the quality of coatings. Laser treatments applied simultaneously during the spraying process deeply modify the coatings microstructure. These hybrid technologies allow in situ laser melting of coatings, resulting in improved mechanical properties and enhanced wear and corrosion behaviors. Finally, laser posttreatments can improve coatings density and adhesion, and also induce phase transformations and structure refinement. As a summary, laser treatments seem particularly promising for improving the thermal spray coating microstructure and the coating/substrate adhesion. In addition, they offer a more environmentally friendly alternative to the conventional surface preparation treatments. © 2011 ASM International.


Roux S.,LGECO LISS | Bur N.,LGECO LISS | Ferrari G.,TNO | Tribollet B.,University Pierre and Marie Curie | Feugeas F.,LGECO LISS
Materials and Corrosion | Year: 2010

Among the multitude of concrete structure pathologies, corrosion of rebars is one of the most important problems of concrete durability. In the context of sustainable development, it appears of primary importance to develop new means to protect the rebars against corrosion. This study aims to develop a new eco-friendly and corrosion-inhibiting admixture based on EPS 180 exopolysaccharides, biopolymers used in coatings already studied for the corrosion inhibition on steel in seawater. C15 rebars embedded in CEMI and CEMV cement paste containing EPS 180 were immersed in natural seawater and their electrochemical behaviour was studied using open circuit potential measurements and electrochemical impedance spectroscopy. These tests highlight the decrease of the cathodic reaction kinetics due to the EPS 180 action at the rebars surface, and the absence of effect on the passive layer. Capillary imbibition tests carried out on cement paste and mortars showed that although limiting the imbibition kinetics for cement pastes, the EPS 180 did not influence the water imbibition of mortars. Tests comparing capillary imbibition of soaked cement pastes and mortars with EPS 180 solution and the same samples containing the EPS 180 admixture highlight that the corrosion inhibition induced by EPS 180 admixture is more due to the modification of the cement - rebars interface than to the clogging of the cement porous network. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Serres N.,LGeCo LISS | Tidu D.,LGeCo LISS | Sankare S.,IREPA LASER Pole API Parc dInnovation | Hlawka F.,LGeCo LISS
Journal of Cleaner Production | Year: 2011

CLAD® process (Direct additive laser manufacturing, Construction Laser Additive Directe in French) allows the direct manufacturing of small parts, and especially in case of complex shapes, giving equivalent properties with traditional processes such as conventional machining or casting techniques. Present environmental considerations are very important for updates in legislation or in order to make economic allowances. A specified mechanical Ti6Al4V part is used as a support and SimaPro software allows to perform Life Cycle Assessment. This study suggests that the absence of chips production, which represents up to 80% of the titanium consumption, provides to CLAD® process an unquestionable advantage. This process requires longer times of execution, which increase additional energy consumptions, and the comparison of this process with conventional machining demonstrates that damages to resources and to human health are highly reduced. In both cases a large part of the environmental impacts are due to the powder elaboration. Finally, CLAD® process can add shapes on machined/casted parts and it is possible to consider the manufacture of a mechanical part via a hybrid process. © 2010 Elsevier Ltd. All rights reserved.


Serres N.,LGECO LISS | Hlawka F.,LGECO LISS | Costil S.,University of Technology of Belfort - Montbéliard | Langlade C.,University of Technology of Belfort - Montbéliard | MacHi F.,IREPA LASER Pole API Parc dInnovation
Applied Surface Science | Year: 2011

Thermal spraying is already used in industry to protect mechanical parts against wear and/or corrosion, but results are not always satisfactory due to porosity and microstructures. In this study, atmospheric plasma spraying (APS) and in situ laser irradiation by diode laser processes were combined to modify structural characteristics of metallic NiCrBSi and composite NiCrBSi-WC coatings. The microstructure evolution was studied with the chemical composition analysis by XRD and SEM coupled with EDS techniques. Instrumented nanoindentation tests were also conducted employing a Berkovich indenter. Moreover, the effect of the influence of the volume fraction of the reinforcing WC particles on the formation and mechanical performances of the layer was also investigated. Results show that in situ laser remelting induces the growth of a dendritic structure which strongly decreases the porosity of as-sprayed coatings, without solidification cracking (one of the major defects that can occur during the solidification of metallic or composite alloys) and improves the mechanical properties of the layer. Indeed, the layer properties such as hardness, elastic modulus, shear strength and wear rate are dependent on the percentage of WC particles in the mixture. © 2010 Elsevier B.V. All rights reserved.


Serres N.,LGeCo LISS | Hlawka F.,LGeCo LISS | Costil S.,University of Technology of Belfort - Montbéliard | Langlade C.,University of Technology of Belfort - Montbéliard | MacHi F.,IREPA LASER
Journal of Materials Processing Technology | Year: 2011

This study aims at evaluating the effect of an in situ laser remelting treatment of NiCrBSi coatings, deposited by plasma spraying. Life Cycle Assessment (LCA) method was used to estimate the environmental impacts of coating processes. It was demonstrated with this LCA that the in situ remelting process was clean. Microstructural results were also evaluated. A good metallurgical bond was formed at the remelted coating interface. Scanning electron microscopy observation revealed also that laser treatment induces a change of the microstructure from lamellar to columnar dendritic. The dependence between the microstructure of NiCrBSi coatings, which was modified by laser treatment, and corrosion resistance has been evaluated by potentiodynamic polarization curves. Results show that, the corrosion resistance was increased because of a finer structure and higher densities of the coatings, but corrosion mechanisms occurring in all cases were different. From the electrochemical experiments in NaCl solution it can be deduced that laser remelting of as-sprayed coatings does not affect their corrosion rate. Corrosion evolves due to a progressive penetration of the electrolyte through the disturbed structure of the as-sprayed samples, whereas the substrate surface of remelted coating is not reached, because of a higher density. But ClMO intermediate species were formed on the surface, because Cl- can destroy the protective film on the coating. The hybrid plasma/laser process was cleaner than hard chromium plating and its corrosion behavior is superior too. © 2010 Elsevier B.V. All rights reserved.


Serres N.,LGeCo LISS | Hlawka F.,LGeCo LISS | Costil S.,University of Technology of Belfort - Montbéliard | Langlade C.,University of Technology of Belfort - Montbéliard | MacHi F.,IREPA LASER
Journal of Thermal Spray Technology | Year: 2011

This paper deals with coating alternatives to hard chromium plating. Thermal spraying is already used in industry, but results are not always satisfactory for reasons of porosity and microstructures. In this study, atmospheric plasma spraying (APS) and in situ laser irradiation by diode laser processes were combined to modify the structural characteristics of thick NiCrBSi alloy layers. The microstructure evolution was studied, and results show that in situ laser remelting induced the growth of a dendritic structure, which strongly decreased the porosity of as-sprayed coatings and increased the adhesion on the substrate. Moreover, no phase transition after laser treatment was observed. Lastly, a mechanical investigation demonstrated that the combination between plasma spray and in situ melting with a diode laser could result in very good mechanical properties. The increase of the laser incident power involved an increase of the mean contact pressure, along with coating hardness. The hybrid process appears to be a possible alternative to hard chromium plating, in order to protect mechanical parts, because of the improved mechanical properties of the NiCrBSi layer. © 2010 ASM International.


Serres N.,LGECO LISS | Hlawka F.,LGECO LISS | Costil S.,University of Technology of Belfort - Montbéliard | Langlade C.,University of Technology of Belfort - Montbéliard | Machi F.,IREPA LASER
Wear | Year: 2011

Electrolytic hard chromium has proved to be effective against wear. However, its use is about to decrease due to the toxic and carcinogenic characteristics of hexavalent chromium. A lot of promising alternatives have been already studied. Among them, thermal spraying presents a good potential. In this study, laser remelting was combined simultaneously to thermal spraying in order to modify a metal alloy coating characteristics. The mechanical properties of a nickel-base layer were investigated by nanoindentation, scratch tests, interfacial indentation and tribological ball-on-disc experiments. The influence of the coating structures on the wear behaviour of in situ remelted NiCrBSi coatings was investigated. This paper demonstrates that the remelted samples have better mechanical performances than as-sprayed coatings. Moreover, the adhesion of remelted samples was strongly increased, as well as the fracture toughness. According to the selected processing parameters, the increase of the laser energy density seems to show better mechanical results. © 2011 Elsevier B.V.


Serres N.,LGECO LISS | Hlawka F.,LGECO LISS | Costil S.,University of Technology of Belfort - Montbéliard | Langlade C.,University of Technology of Belfort - Montbéliard | Machi F.,IREPA LASER
Surface and Coatings Technology | Year: 2010

The alternative coatings to electrodeposited hard chromium plating are studied nowadays, because of the chemical composition of the baths containing Cr(VI), forbidden by several European regulations. Thermal spraying is already used in industry, but the deposited coatings still need improvements for reasons of porosity and microstructures. In this study, atmospheric plasma spraying and in situ laser irradiation by diode laser processes were combined to modify the structural characteristics of NiCrBSi coatings. The microstructure evolution was studied, with the analysis of chemical composition using energy-dispersive spectroscopy and X-ray diffraction. Results show that in situ laser remelting induces the growth of a dendritic structure which strongly decreases the porosity of as-sprayed coatings and no phase transition after laser treatment. The adopted configuration drives to the achievement of coatings without solidification cracking, one of the major defects that can occur during the solidification of metallic alloys. Furthermore, to evaluate the environmental impacts of coatings in comparison with other conventional treatments developed to melt NiCrBSi layers, a Life Cycle Assessment was carried out. The ecodesign of surface coatings has not been reported in detail in the current literature, and nowadays, life cycle analysis is an important consideration for the thermal spray community. The good environmental assessment of the hybrid process is demonstrated in this paper. © 2010 Elsevier B.V.


Serres N.,LGeCo LISS | Portha N.,IREPA LASER | Machi F.,IREPA LASER
Surface and Coatings Technology | Year: 2011

NiCrBSi materials are widely used in applications where corrosion and wear resistance are required. This Ni-based alloy has been deposited onto C38 steel disc using the laser cladding technique. This paper describes the results of experiments that were performed using pin-on-disc tribometer and Knoop indentation on aging tests, for different exposure times, in a salt spray booth. Salt spray corrosion tests have shown that over 800h of exposure, samples exhibit very high corrosion resistance. Mechanical properties, as well as wear behaviour are not affected under these conditions, due to the formation of Cr2O3 on the surface. However, for longer exposure (aging) time, wear behaviour was affected because of a pit distribution as well as chlorine presence on the surface. Thus, the mechanical properties deteriorated. © 2011 Elsevier B.V.

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