Vincent Demers

• Professor
• Professor at École de Technologie Supérieure

Material extrusion (MEX) 3D printing of highly filled polymer has demonstrated great capabilities for prototyping or rapid manufacturing of metallic parts exhibiting complex shapes. However, only a few studies have quantitatively examined the dimensional properties of simple shape printed parts and virtually none has investigated the correlation be...

Purpose The purpose of this study is to determine the material extrusion (MEX) printability envelope of a new kind of low-viscosity powder-binder feedstocks using rheological properties. Design/methodology/approach Formulation of 13 feedstocks (variation of solid loading 60–67 Vol.% and thickening agent proportion 3–15 Vol.%) that were characteriz...

Controlling injection parameters is paramount when it comes to producing high-quality green parts using powder injection molding. This work combines experimental and numerical approaches to study the impact of injection parameters on mold in-cavity pressure and on the overall quality of green parts produced by low-pressure powder injection molding....

The present work aims to explore the ability to simulate flow patterns and the velocity field in the powder injection molding (PIM) process using the smoothed particle hydrodynamics (SPH) method. Numerical simulations were performed using the DualSPHysics platform. A feedstock formulated from 17-4 PH stainless steel powder (60 vol. % of powder) and...

This study aims to compare the flow patterns and in-cavity pressures obtained experimentally and numerically for different conditions. Four feedstocks based on 17-4PH stainless steel powder were fully characterised and implemented as material laws in an Autodesk Moldflow package before to obtain numerical simulations that were then validated using...

The surface energy of various mold materials for low-pressure powder injection molding was evaluated using values of contact angles (Owens–Wendt method), and correlated with the feedstock moldability and mold adhesion. The surface tension of the binder used to formulate a metallic-based feedstock was also measured in the molten state at a typical i...

The surface energy of various mold materials for low-pressure powder injection molding was evaluated using values of contact angles (Owens-Wendt method), and correlated with the feedstock moldability and mold adhesion. The surface tension of the binder used to formulate a metallic-based feedstock was also measured in the molten state at a typical i...

In recent years, increasing attention has been directed at the material extrusion additive manufacturing of highly-filled polymers (MEAM-HP). This is because conventional polymer 3D printers, which are low cost and readily available, can easily be adapted for use with metal powder-filled polymer filaments. However, fabricating the latter is time-co...

Low-pressure powder injection moulding (LPIM) is a cost-effective manufacturing technology used to fabricate complex-shaped parts with high mechanical properties at low- or high-volume production. This research work presents an experimental approach to investigate the debound/sintered properties of iron components produced by the LPIM process using...

Low-pressure powder injection molding (LPIM) is a cost-effective technology for producing intricate small metal parts at high, medium, and low production volumes in applications which, to date, have involved ceramics or spherical metal powders. Since the use of irregular metal powders represents a promising way to reduce overall production costs, t...

The effect of laser wave modes on the fatigue behavior of laser cold-wire welding made of 4.8 mm thick AA6005-T6 aluminum alloy was investigated using continuous and pulsed wave lasers. Due to the inherent differences in these two wave laser modes, different welding parameters were used, while keeping the interaction time constant. The mechanical p...

Free download ==> https://authors.elsevier.com/a/1XGlnWK0QG2a5 ********************************************************* The fatigue properties of gas metal arc welded and friction stir welded assemblies made of aluminum alloy AA6061-T6 structural extrusions were examined. The mechanical performances of welded joints were obtained using uniaxial t...

Moldability and segregation of feedstock are linked to the rheological behavior of the powder-binder mixture. In this study, the impact of binders on viscosity and segregation of feedstocks was investigated. The experiments were conducted on several feedstocks obtained by mixing Inconel 718 powder with paraffin wax-based binder systems. The viscosi...

In low-pressure powder injection molding, the injection presses are equipped with an interconnecting pipe in which the segregation of feedstocks may occur during the dead time of the process. This segregation phenomenon limits the use of low-viscosity feedstocks leading to a decrease in the capacity to produce more complex-shaped components. The fu...

The rheological behavior of wax-based feedstocks has a direct impact on successful mold filling for parts produced by low-pressure powder injection molding. During a rheological test, segregation may occur within low-viscosity feedstocks, leading to errors in results, and to an improper evaluation of the flowability of powder-binder mixtures. The s...

The purpose of this work was to investigate tensile and fatigue behaviors of Inconel 625 superalloy brazed joints after transient liquid-phase bonding process. Brazing was performed in a vacuum furnace using a nickel-based filler metal in a form of paste to join wrought Inconel 625 plates. Mechanical tests were carried out on single-lap joints unde...

The impact of binders and temperature on the rheological properties of feedstocks used in low-pressure powder injection molding was investigated. Experiments were conducted on different feedstock formulations obtained by mixing Inconel 718 powder with wax-based binder systems. The shear rate sensitivity index and the activation energy were used to...

Low-pressure metal injection molding (LP-MIM) is an advanced manufacturing technology where a wax-based feedstock is injected into a complex shape before densification heat treatments. Feedstock is generally designed to minimize segregation, maximize flowability, maximize the strength of the molded component, maximize the solid loading potential an...

This article describes the evolution of structural and functional properties of Ti–Ni SMA as a result of thermomechanical processing combining cold/warm deformation ranging from moderate to severe and post-deformation annealing at different temperatures. This study results in the development of an original thermomechanical processing route capable...

In this study, three measurement techniques were experimentally compared to quantify the effects of segregation on powder injection molding feedstock. In a powder metallurgy process, particle or phase segregation generates a fluctuation of the particle distribution in powder–binder mixture from point-to-point. Such demixing occurs generally before...

Rheological behavior of powder-binder mixture has a direct impact on the successful mold filling for parts obtained from powder injection molding. In this study, the impact of binders on rheological properties of feedstocks was investigated. The experiments were conducted on several feedstocks obtained by mixing of Inconel 718 powder with wax-based...

Introduction Materials, Equipment and Methodology Results and Discussion Conclusions Acknowledgements

Thermomechanical processing consisting of cold rolling (e=0.3–2.0) and post-deformation annealing (300–450°C, 1h) was applied to binary Ti–Ni alloys to produce nanocrystalline structures (NS) or polygonized dislocation substructures (PDS), or their mixture. The evolution of the material structure and properties was studied using TEM, X-ray, microha...

Thermomechanical processing consisting of cold rolling (e=0.3-2.0) and post-deformation annealing (300-450oC, 1h) was applied to binary Ti-Ni alloys to produce nanocrystalline structures (NS) or polygonized dislocation substructures (PDS), or their mixture. The evolution of the material structure and properties was studied using TEM, X-ray, microha...

A Ø 1.0 mm Ti–50.26 at% Ni wire is cold rolled by varying its true thickness reduction from e = 0.25 to 2.0 and then annealed (400 °C, 1 h) to obtain a nanoscale grain structure or a polygonized dislocation substructure, or a mixture of both. The Ti–Ni alloy is characterized using three complementary fatigue measurement techniques: (a) stress-free...

A Ø 1.0 mm Ti–50.26 at.% Ni wire is cold rolled by varying its thickness reduction (true thickness reduction from e = 0.25 to 2.0), the back and forward pulling tensions applied to the strip (from 0.1 to 0.5 of the material yield stress, σy) under dry and lubricated conditions, and then annealed to obtain a nanoscale grain structure or polygonized...

L'objectif de ce projet est de determiner les conditions de laminage et la temperature de traitement thermique maximisant les proprietes fonctionnelles de l'alliage a memoire de forme Ti-Ni. Les specimens sont caracterises par des mesures de calorimetrie, de microscopie optique, de gene ration de contrainte, de deformation recuperable et des essais...

A Ti-50.26at.%Ni alloy wire has been cold rolled in dry and lubricated conditions from 0.3 to 2.0 logarithmic thickness reduction with variable forward and back pulling tensions, and annealed in the 200 to 700°C temperature range for 1 hour. Differential scanning calorimetry testing has been carried out to evaluate the presence of the amorphized an...

The main functional properties (FP) of Ti-Ni Shape Memory Alloys (SMA) are their critical temperatures of martensitic transformations, their maximum completely recoverable strain (er,1 max) and maximum recovery stress (sr max). Control of the Ti-Ni-based SMA FP develops by forming well-developed dislocation substructures or ultrafine-grained struct...

The substructure and structure formation as well as the mechanical and functional properties of thermomechanically treated Ti–50.7at.%Ni and Ti–50.0at.%Ni alloys were studied using transmission electron microscopy and mechanical testing. A low-temperature thermomechanical treatment is carried out by rolling at room temperature in a true strain rang...

The thermomechanical processing consisting in severe cold rolling (true strain 0.7–1.9) followed by a post-deformation annealing (200-700oC) is applied to Ti-50.0 and 50.7at%Ni alloys. The thermal stability of the amorphous phase as well as the influence of post-deformation annealing on the structure, substructure and temperature range of martensit...

Description Get the latest information on the thermal and mechanical properties of shape memory alloys (SMA's) and metallic medical materials and devices. Eleven peer-reviewed papers: • Define the environments in body-specific locations such as the superficial femoral artery, carotid, abdominal and thoracic arteries • Develop constitutive expressio...

Thermomechanical processing with extended deformation and temperature ranges and their influence on the structure and properties of the equiatomic Ti–Ni shape memory alloy are studied using transmission electron microscopy, differential scanning calorimetry, electrical resistivity, tensile and specialized thermomechanical testing techniques. The de...

Ti-50 at % Ni alloy wire is subjected to cold-rolling (true strain e=0.3-1.9) and post-deformation annealing (200-700°C range). For all levels of cold work, the maxima of recovery strain and stress are obtained after annealing in the 350-400°C range. For the moderately-to-high cold-worked material (e=0.3-0,88), this annealing leads to polygonizatio...

The thermomechanical processing consisting in cold work (true strain e ¼ 0:3{1:9) followed by a post-deformation annealing (200–700 C temperature range) is applied to the equiatomic Ti–Ni alloy. The evolution of the structure, substructure and functional properties of the material is studied. For all levels of cold work, the maxima of the free reco...

Substructure and structure formation as well as functional properties of thermomechanically treated Ti-Ni wire have been studied using differential scanning calorimetry, X-ray diffraction, transmission electron microscopy and mechanical. The low- temperature themomechanical treatment (LTMT) was carried out by rolling at room temperature in a true s...

Comparative investigation of the structure formation and changes in the functional properties and deformation behavior of the Ti-50.0% Ni shape-memory alloy as a result of low-temperature thermomechanical treatment at true rolling strains e = 0.30-1.9 with subsequent annealings at 200-700°C was performed. The alloy with a nanocrystalline structure...

The effect of various modes of thermomechanical treatment, including intense plastic deformation and postdeformation annealing, on the structure, mechanical, and functional properties of alloys based on titanium nickelide is investigated. The advantages of intense plastic deformation with annealing are shown as compared with traditional thermomecha...