Pierre Sallamand
University of Burgundy
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Publication
Featured researches published by Pierre Sallamand.
Journal of Thermal Spray Technology | 2012
Gilles Rolland; Pierre Sallamand; Vincent Guipont; Michel Jeandin; E. Boller; Christine Bourda
This work demonstrated the feasibility of cold spray for the achievement of industrial electrical contacts to be used in contactors and circuit breakers. This resulted from the study of cold spray conditions when applied to two types of silver-based particulate composites. Starting materials, primarily powder characteristics and addition content, and spraying conditions were optimized from thorough studies of microstructures and mechanical properties of the cold-sprayed composites. These involve x-ray microtomography and transmission electron microscopy in particular, in addition to tensile tests. Moreover, thermomechanical laser testing of series of cold-sprayed microstructures was successfully developed to investigate into damage mechanisms in coatings. The whole led to a novel phenomenological approach to damage in cold-sprayed materials. Durability tests of the best coatings were carried out using industrial facilities. Cold-sprayed contacts compared more than well with those from conventional powder metallurgy (P/M), which opens a new and cost-attractive production route for electrical contacts.
International Congress on Applications of Lasers & Electro-Optics | 2005
Nicolas Pierron; Pierre Sallamand; Simone Matteï
Laser welding offers many advantages over conventional techniques, but is subject to a great number of different parameters. Whereas a purely experimental study would be very expensive, modelling the process can optimize it more economically. Laser welding leads to the occurrence of physical phenomena that do not appear in conventional welding. Modelling presents several difficulties arising from the following: the strong thermal gradients present over short distances; the evaporation of the material, leading to a deformation of the free surface; the appearance of a keyhole-like cavity if the recoil pressure becomes particularly high. Marangoni convection, initiated by surface tension gradients, has a considerable effect on thermal transfer in the melted pool and, consequently, on the enlargement of the melted pool. The latent heat of fusion and vaporization are introduced into the model as sources in the heat equation. The Newton-Stokes equations are modified to model the flow in the solid-liquid zone. The model takes into account the non-linearities arising from the variations, with temperature, of thermophysical characteristics. The results of a 2D numerical calculation for a laser pulse (Nd : YAG) on a sheet of aluminium are presented here. FEMLAB, a software based on the finite element method, was used.Laser welding offers many advantages over conventional techniques, but is subject to a great number of different parameters. Whereas a purely experimental study would be very expensive, modelling the process can optimize it more economically. Laser welding leads to the occurrence of physical phenomena that do not appear in conventional welding. Modelling presents several difficulties arising from the following: the strong thermal gradients present over short distances; the evaporation of the material, leading to a deformation of the free surface; the appearance of a keyhole-like cavity if the recoil pressure becomes particularly high. Marangoni convection, initiated by surface tension gradients, has a considerable effect on thermal transfer in the melted pool and, consequently, on the enlargement of the melted pool. The latent heat of fusion and vaporization are introduced into the model as sources in the heat equation. The Newton-Stokes equations are modified to model the flow in the solid-liquid zone. T...
Optics and Laser Technology | 2001
Sorin Ignat; Pierre Sallamand; Alexandru Nichici; A. B. Vannes; Dominique Grevey; E Cicală
Abstract There are very strong interests in developing low density advanced material systems for service at temperatures up to 1300°C. These materials should mainly have moderate fracture toughness at low and intermediate temperatures and should exhibit oxidation resistant behaviour. The intermetallic compound, MoSi 2 has been considered to be an attractive candidate due to its melting point (2030°C) and excellent oxidation resistance at high temperatures. In this paper, we compare the results obtained with two different techniques for laser cladding, one using an online combination between Mo and Si powders, the second using direct injection of the MoSi 2 powder.
Applied Mathematics and Computation | 2013
Iryna Tomashchuk; Pierre Sallamand; J.M. Jouvard
A multiphysical model of high power beam welding of immiscible materials is developed to explain the influence of operational parameters and materials properties on resulting morphology by simultaneous solving of heat transfer, fluid flow and mass transfer problems. The introduction of phase field description of the interface motion between two immiscible liquids allows obtaining the cartography of melted zone in function of two key-parameters: the position of heat source relatively to joint line and the welding speed. Due to the short thermal cycle limiting mass transfer, high power beam welding techniques may result in very inhomogeneous melted zones. In this study, the interest is paid to copper to stainless steel Nd:YAG laser and electron beam joints, which often present the repetitive heterogeneous patterns. The modeling results are validated by the comparison with experimental data on weld shape, composition and morphology.
Surface & Coatings Technology | 2003
Sorin Ignat; Pierre Sallamand; Alexandru Nichici; Bernard Vannes; Dominique Grevey; Eugen Cicală
Abstract In the last decade, development of low density advanced material systems for service at temperatures up to 1300 °C was one of the goals of many researches. This kind of material should mainly have moderate fracture toughness and should exhibit oxidation resistant behaviour at low and intermediate temperature. One of the most studied materials continues to be the intermetallic compound MoSi 2 . The molybdenum disilicide has been considered as an attractive candidate due to its melting point (2030 °C) and excellent oxidation resistance at high temperatures. The main problem associated with the MoSi 2 layer synthesized using laser beam is the layer fragility. To avoid this fragility, unstabilized zirconia was employed in many cases. The paper presents the reasons, the set-up and the results of a new powder injection technique that uses two powders (MoSi 2 and ZrO 2 ) to produce the cladding using a Nd:YAG cw laser beam.
Intermetallics | 2003
Sorin Ignat; Pierre Sallamand; Alexandru Nichici; Bernard Vannes; Dominique Grevey; Eugen Cicala
Abstract The cladding process using laser beam radiation comprises different operational regimes, depending on the involved lasers (usually CO 2 or Nd:YAG) and materials. A series of experiments has been carried out to investigate Nd:YAG laser cladding using MoSi 2 powder. Procedures and operating parameters for producing clad layers has been developed and their properties evaluated. The feasibility of the laser cladding technique, using a high power Nd:YAG laser, by projecting MoSi 2 powder on steel substrate was demonstrated. The results indicate a low density of cracks, elevated powder catchment efficiency (between 65 and 90%) and hardness values around 1200–1300 HV. Our goal consists in crack reduction (ideally elimination) and to reach that we have considered the addition of components that can create opposing stresses during solidification, like non-stabilized Zirconia powder particles. The results of these experiments are also widely presented in the paper.
Journal of Physics D | 2007
Nicolas Pierron; Pierre Sallamand; J.M. Jouvard; Eugen Cicala; Simone Matteï
Welding laser modelling requires knowledge about relative changes of many thermo-physical parameters involved in the interaction. The absorptivity of the material is one of the most important. In this study, experimental measurements of absorptivity with an integrating sphere on two alloys (aluminium and magnesium) were made. These results were compared with an analytical calculation that takes into account the trapping of the beam by multiple reflections inside the keyhole. Based on a statistical method, an empirical law is proposed connecting absorptivity with the peak power of the laser and the duration of interaction. During the interaction, two distinct phenomenologies are brought to light. A threshold is then defined after which the physical process becomes stable. Below this threshold, the measurement of absorptivity is problematic, and the values are widely dispersed.
Solid State Phenomena | 2016
Ioan Catalin Mon; Mircea Horia Tierean; Eugen Cicala; Michel Pilloz; Iryna Tomashchuk; Pierre Sallamand
This paper studies the ductile iron (DI) weldability using laser welding. For performing an Yb:YAG continuous laser was used, with a maximum power of 6 kW. The parametrical window power (P) - welding speed (S) was explored by carrying out the fusion lines on ductile iron plates without preheating, to determinate areas of weldability (complete penetration, correct geometry) to allow further characterization. The criteria for selection of focus areas were the geometry of the fusion lines and the absence of the welding defects. The unsatisfactory domains were characterized by: collapse of the melted metal, incomplete penetration, low fusion lines quality (geometry, compactness). In present study, several values of power and welding speed have been tested to identify their influence on geometry, compactness of the joints and mechanical properties. As result, the power-welding speed diagram for feasible domains of laser welding was generated.
International Congress on Applications of Lasers & Electro-Optics | 2012
Issam Bendaoud; Simone Matteï; Eugen Cicala; Iryna Tomashchuk; Henri Andrzejewski; Pierre Sallamand; Alexandre Mathieu; Amelie Fanica
The present study is dedicated to the numerical simulation of an industrial case of hybrid laser-MIG welding of high thickness duplex steel UR2507Cu with Y-shaped gap geometry. It consists on stimulating the heat transfer during the welding by COMSOL Multiphysics software using heat equivalent source approach. A numerical exploratory designs method is used to identify and to optimize the heat sources parameters in order to obtain a small relative error between the numerical results and the experiment.
International Congress on Applications of Lasers & Electro-Optics | 2006
Nicolas Pierron; Pierre Sallamand; Simone Matteï
In the laser processes such as laser welding and heat surface treatment, the absorption factor of laser Nd :YAG by metals plays a very important role. Its evolution depends on many parameters such as temperature or surface conditions. In this paper, we present a method based on the measurement of reflected energy during the laser process, carried out on two types of magnesium alloys (WE43 and RZ5) and aluminum alloy 1xxx. An integrating sphere coupled with a photodiode and a numerical oscilloscope is used.In the laser processes such as laser welding and heat surface treatment, the absorption factor of laser Nd :YAG by metals plays a very important role. Its evolution depends on many parameters such as temperature or surface conditions. In this paper, we present a method based on the measurement of reflected energy during the laser process, carried out on two types of magnesium alloys (WE43 and RZ5) and aluminum alloy 1xxx. An integrating sphere coupled with a photodiode and a numerical oscilloscope is used.