Développement et caractérisation de mélanges polymères-poudres métalliques pour le micro moulage par injection

Micro-Powder Injection Moulding (Micro-PIM) technology is one of the key technologies that permit to fit with the increasing demands for smaller parts associated to miniaturization and functionalization in different application fields. The thesis focuses first on the elaboration and characterization of polymer-powder mixtures based on 316L stainless steel powders, and then on the identification of physical and material parameters related to the sintering stage and to the numerical simulations of the sintering process. Mixtures formulation with new binder systems based on different polymeric components have been developed for 316L stainless steel powders (5 µm and 16 µm). The characterization of the resulting mixtures for each group is carried out using mixing torque tests and viscosity tests. The mixture associated to the formulation comprising polypropylene + paraffin wax + stearic acid is well adapted for both powders and has been retained in the subsequent tests, due to the low value of the mixing torque and shear viscosity. The critical powder volume loading with 316L stainless steel powder (5 µm) according to the retained formulation has been established to 68% using four different methods. Micro mono-material injection (with 316L stainless steel mélange) and bi-material injection (with 316L stainless steel mélange and Cu mélange) are properly investigated. Homogeneity tests are observed for mixtures before and after injection. A physical model well suited for sintering stage is proposed for the simulation of sintering stage. The identification of physical parameters associated to proposed model are defined from the sintering stages in considering 316L stainless steel (5 µm)mixtures with various powder volume loadings (62%, 64% and 66%). Beam-bending tests and free sintering tests and thermo-Mechanical-Analyses (TMA) have also investigated. Three sintering stages corresponding to heating rates at 5 °C/min, 10 °C/min and 15 °C/min are used during both beam-bending tests and free sintering tests. On basis of the results obtained from dilatometry measurements, the shear viscosity module G, the bulk viscosity module K and the sintering stress σs are identified using Matlab® software. Afterwards, the sintering model is implemented in the Abaqus® finite element code, and appropriate finite elements have been used for the support and micro-specimens, respectively. The physical material parameters resulting from the identification experiments are used to establish the proper 316L stainless steel mixture, in combination with G, K and σs parameters. Finally, the sintering stages up to 1200 °C with three heating rates (5 °C/min, 10 °C/min and 15 °C/min) are also simulated corresponding to the four micro-specimen types (powder volume loading of 62%, 64% and 66%). The simulated shrinkages and relative densities of the sintered micro-specimens are compared to the experimental results indicating a proper agreementLe micro-moulage par Injection de Poudres (Micro-PIM) est l’une des technologies permettant de réaliser des micro-composants de très petites dimensions, associés à la miniaturisation et la fonctionnalisation dans différents domaines d’applications. La thèse concerne l’élaboration et la caractérisation de mélanges basés sur des poudres d’acier inoxydable de type 316L, l’identification des paramètres physiques associés à l’étape de densification est traitée. Des modélisations physiques et des simulations numériques de l’étape de densification par diffusion à l’état solide, sont ensuite proposées.De nouvelles formulations de mélanges à base de liants polymériques ont été développées pour différentes granulométries de poudres d’acier inoxydable de type 316L (5 µm et 16 µm). Les différents mélanges élaborés ont été élaborés et validés grâce à des comparatifs entre couples de mélangeages et courbes de viscosité de cisaillement. Les mélanges élaborés avec une formulation de base composée de polypropylène, de cire paraffine et d’acide stéarique, sont adaptés pour les deux types de poudre, et conduisent à des résultats significatifs pour les différents tests réalisés, conduisant à un couple de mélangeage et à une viscosité de cisaillement relativement faibles par rapport aux autres formulations. Le taux de charge critique obtenu pour l’acier inoxydable 316L (5 µm), avec la formulation optimale, est de 68% et a été déterminé par différentes méthodes. Les essais de micro-injection pour le mono-matériau (316L mélange) et les bi-matériaux (mélange de 316 L et Cu) ont été analysés en détail. Des tests d’homogénéité ont été réalisés avant et après l’étape d’injection.Un modèle thermo-élasto-viscoplastique approprié pour modéliser l’étape de densification a été utilisé pour la simulation de la densification des micro-composants. Les paramètres d’identification du modèle physique ont été identifiés pour des mélanges de poudres d’acier 316L (5 µm), pour différents taux de charge (62%, 64% et 66%). Des essais de flexion 3 points et de compression ont été réalisé à l’intérieur d’un dilatomètre vertical avec trois cinétiques de densification (5 °C/min, 10 °C/min et 15 °C/min). Les résultats obtenus par dilatométrie, ont permis l’identification du module de viscosité de cisaillement G, du module de compressibilité K, et de la contrainte de densification σs, Le modèle de comportement associé à la densification, incluant les paramètres identifiés a été implémenté dans le code éléments finis Abaqus©. Des éléments finis adaptés ont été utilisés, tant pour le support, que les quatre micro-éprouvettes de référence. Les simulations de l’étape de densification pour trois différentes cinétiques (5 °C/min, 10 °C/min et 15 °C/min) à 1200°C, ont été réalisées pour l’ensemble des micro-composants dont les taux de charge correspondent respectivement à 62%, 64% et 66%. Les retraits et densités relatives des micro-composants obtenus par simulation sont en très bonne corrélation avec les résultats expérimentau

Manufacturing of stainless steel and Cu Bi-material micro-components with a micro-powder injection molding process

International audienceImportant research tasks at Femto-ST and Ensmm concern the micro powder injection molding. Principle of this process is the manufacturing of complicated metallic micro-components via replication of die cavity mould. The feedstock realized with metallic powders has been developed and characterized. Certain optimal formulations have been selected by testing the different feedstock formulations with various polymer binders (polypropylene, wax and stearic acid). In the paper, bi-injection with the adaptive feedstocks has been realized

Determination of critical and optimal powder loadings for 316L fine stainless steel feedstocks for micro-powder injection molding

International audienceAdapted from powder injection molding (PIM), the micro-PIM technology satisfies the increasing demands for functionalization and miniaturization of micro-parts. Research works in this area have been carried out through micro injection molding tests issued from mixtures consisting in 316L stainless steel fine powders with D50 = 3.4 µm and different thermoplastic polymeric binders. The well appropriate polymer–powder formulations are composed with different binders. The binders have been adapted to micro-injection and tested to find out an optimum feedstock. The rheological characterization of the elaborated feedstock has been carried out according to the selected stainless steel powders and polymers. Thecritical powder volume loading has been determinated and fixed in the range of 68–70%, and the optimal powder volume loading has been chosen around 66% for 316L stainless steel feedstock (D50 = 3.4 µm). This choice has been confirmed by processing of the micro-components with the retained feedstock loaded up to 66 %

Développement et caractérisation de mélanges polymères-poudres métalliques pour le micro moulage par injection

Le micro-moulage par Injection de Poudres (Micro-PIM) est l une des technologies permettant de réaliser des micro-composants de très petites dimensions, associés à la miniaturisation et la fonctionnalisation dans différents domaines d applications. La thèse concerne l élaboration et la caractérisation de mélanges basés sur des poudres d acier inoxydable de type 316L, l identification des paramètres physiques associés à l étape de densification est traitée. Des modélisations physiques et des simulations numériques de l étape de densification par diffusion à l état solide, sont ensuite proposées.De nouvelles formulations de mélanges à base de liants polymériques ont été développées pour différentes granulométries de poudres d acier inoxydable de type 316L (5 m et 16 m). Les différents mélanges élaborés ont été élaborés et validés grâce à des comparatifs entre couples de mélangeages et courbes de viscosité de cisaillement. Les mélanges élaborés avec une formulation de base composée de polypropylène, de cire paraffine et d acide stéarique, sont adaptés pour les deux types de poudre, et conduisent à des résultats significatifs pour les différents tests réalisés, conduisant à un couple de mélangeage et à une viscosité de cisaillement relativement faibles par rapport aux autres formulations. Le taux de charge critique obtenu pour l acier inoxydable 316L (5 m), avec la formulation optimale, est de 68% et a été déterminé par différentes méthodes. Les essais de micro-injection pour le mono-matériau (316L mélange) et les bi-matériaux (mélange de 316 L et Cu) ont été analysés en détail. Des tests d homogénéité ont été réalisés avant et après l étape d injection.Un modèle thermo-élasto-viscoplastique approprié pour modéliser l étape de densification a été utilisé pour la simulation de la densification des micro-composants. Les paramètres d identification du modèle physique ont été identifiés pour des mélanges de poudres d acier 316L (5 m), pour différents taux de charge (62%, 64% et 66%). Des essais de flexion 3 points et de compression ont été réalisé à l intérieur d un dilatomètre vertical avec trois cinétiques de densification (5 C/min, 10 C/min et 15 C/min). Les résultats obtenus par dilatométrie, ont permis l identification du module de viscosité de cisaillement G, du module de compressibilité K, et de la contrainte de densification s, Le modèle de comportement associé à la densification, incluant les paramètres identifiés a été implémenté dans le code éléments finis Abaqus . Des éléments finis adaptés ont été utilisés, tant pour le support, que les quatre micro-éprouvettes de référence. Les simulations de l étape de densification pour trois différentes cinétiques (5 C/min, 10 C/min et 15 C/min) à 1200C, ont été réalisées pour l ensemble des micro-composants dont les taux de charge correspondent respectivement à 62%, 64% et 66%. Les retraits et densités relatives des micro-composants obtenus par simulation sont en très bonne corrélation avec les résultats expérimentauxMicro-Powder Injection Moulding (Micro-PIM) technology is one of the key technologies that permit to fit with the increasing demands for smaller parts associated to miniaturization and functionalization in different application fields. The thesis focuses first on the elaboration and characterization of polymer-powder mixtures based on 316L stainless steel powders, and then on the identification of physical and material parameters related to the sintering stage and to the numerical simulations of the sintering process. Mixtures formulation with new binder systems based on different polymeric components have been developed for 316L stainless steel powders (5 m and 16 m). The characterization of the resulting mixtures for each group is carried out using mixing torque tests and viscosity tests. The mixture associated to the formulation comprising polypropylene + paraffin wax + stearic acid is well adapted for both powders and has been retained in the subsequent tests, due to the low value of the mixing torque and shear viscosity. The critical powder volume loading with 316L stainless steel powder (5 m) according to the retained formulation has been established to 68% using four different methods. Micro mono-material injection (with 316L stainless steel mélange) and bi-material injection (with 316L stainless steel mélange and Cu mélange) are properly investigated. Homogeneity tests are observed for mixtures before and after injection. A physical model well suited for sintering stage is proposed for the simulation of sintering stage. The identification of physical parameters associated to proposed model are defined from the sintering stages in considering 316L stainless steel (5 m)mixtures with various powder volume loadings (62%, 64% and 66%). Beam-bending tests and free sintering tests and thermo-Mechanical-Analyses (TMA) have also investigated. Three sintering stages corresponding to heating rates at 5 C/min, 10 C/min and 15 C/min are used during both beam-bending tests and free sintering tests. On basis of the results obtained from dilatometry measurements, the shear viscosity module G, the bulk viscosity module K and the sintering stress s are identified using Matlab® software. Afterwards, the sintering model is implemented in the Abaqus® finite element code, and appropriate finite elements have been used for the support and micro-specimens, respectively. The physical material parameters resulting from the identification experiments are used to establish the proper 316L stainless steel mixture, in combination with G, K and s parameters. Finally, the sintering stages up to 1200 C with three heating rates (5 C/min, 10 C/min and 15 C/min) are also simulated corresponding to the four micro-specimen types (powder volume loading of 62%, 64% and 66%). The simulated shrinkages and relative densities of the sintered micro-specimens are compared to the experimental results indicating a proper agreementBESANCON-Bib. Electronique (250560099) / SudocSudocFranceF

Determination of Glufosinate-P-Ammonium in Soil Using Precolumn Derivation and Reversed-Phase High-Performance Liquid Chromatography

This study developed an analytical method to quantify glufosinate-P-ammonium (GLUF-P) in farmland soil using a reversed-phase high-performance liquid chromatography (HPLC) system with a fluorescence detector after derivatization. GLUF-P in farmland soil was extracted with a mixed alkaline solution and was further derivatized with 9-fluorenyl methyl chloroformate (FMOC) at 25 °C for 1 h. The derivatives were separated with an ACE-C18 column, gradient eluted with a mobile phase A of acetonitrile and a mobile phase B of 0.2% phosphoric acid solution, and finally determined by high-performance liquid chromatography (HPLC) with fluorescence detection at an excitation wavelength of 254 nm and an emission wavelength of 279.8 nm. The limits of detection (LODs) in the four types of soil ranged from 0.004 to 0.015 mg/kg, and the limits of quantification (LOQs) ranged from 0.0125 to 0.05 mg/kg. The mean recoveries of GLUF-P ranged from 94% to 119.8%, and the relative standard deviations (RSDs) varied between 2.8% and 9.0% when the spiked concentrations of GLUF-P were 0.1 mg/kg and 1.0 mg/kg, respectively. The coefficients of regression for the linearity equation were more than 0.99. The proposed method had high sensitivity and could be used for the determination of GLUF-P residues in farmland soil

Determination of Glufosinate-P-Ammonium in Soil Using Precolumn Derivation and Reversed-Phase High-Performance Liquid Chromatography

This study developed an analytical method to quantify glufosinate-P-ammonium (GLUF-P) in farmland soil using a reversed-phase high-performance liquid chromatography (HPLC) system with a fluorescence detector after derivatization. GLUF-P in farmland soil was extracted with a mixed alkaline solution and was further derivatized with 9-fluorenyl methyl chloroformate (FMOC) at 25 °C for 1 h. The derivatives were separated with an ACE-C18 column, gradient eluted with a mobile phase A of acetonitrile and a mobile phase B of 0.2% phosphoric acid solution, and finally determined by high-performance liquid chromatography (HPLC) with fluorescence detection at an excitation wavelength of 254 nm and an emission wavelength of 279.8 nm. The limits of detection (LODs) in the four types of soil ranged from 0.004 to 0.015 mg/kg, and the limits of quantification (LOQs) ranged from 0.0125 to 0.05 mg/kg. The mean recoveries of GLUF-P ranged from 94% to 119.8%, and the relative standard deviations (RSDs) varied between 2.8% and 9.0% when the spiked concentrations of GLUF-P were 0.1 mg/kg and 1.0 mg/kg, respectively. The coefficients of regression for the linearity equation were more than 0.99. The proposed method had high sensitivity and could be used for the determination of GLUF-P residues in farmland soil

Viscous behaviours of feedstocks for micro MIM

International audienceThe viscous behavior of feedstocks plays the crucial role in Micro MIM. It affects directly injectability of the components and finally quality of the sintered component, because of the possible segregation induced by injection. The studies on viscosity of the feedstocks are realized by a series ofthe tests, in which a torque rheometer and a capillary rheometer are employed. The effects of binder composition, powder size, temperature and powder loading in volume on viscosity of the feedstocks are investigated. The mixtures of three kinds of binder composition, mixed with 5μm or 16μm 316L stainless steel powders, are evaluated. The best binder composition is determined by comparison of the viscous behaviors among the self-mixed feedstocks and the commercial one. It results in the suitable ranges of heating temperature and powder loading in volume for the feedstocks. The critical powder loading in volume is determined by a series of the capillary tests with the gradual increase of powder loading. These works provide the valuable reference for the research on binder composition and the process of micro metal injection molding

Micro-manufacturing of metallic micro-fluidic devices by soft embossing replication process

International audienceMicro-manufacturing of metallic micro-fluidic devices by soft embossing replication proces

Simulation and Experiment on Phase Equilibrium of Gas Hydrate Using the T-Type Pipe Confluence Model

A constraint of the development of gas hydrate is the phase change that may cause engineering losses in the mining process, which tends to be clogged in the section of well completion (sieve section: wellbore lifting section). The flow of gas hydrate in the well completion section was simplified using the T-type pipe confluence model in this paper. The temperature and pressure coupling model in the confluence section was derived first, followed by the use of the Fluent software to simulate its gradient changes in the T-type model. Then, the physical model and the experiment were designed to study the velocity changes. Finally, the contrast analysis between experiment and numerical simulation was carried out. Through the study of this paper, it is possible to prevent blockage in the well completion section during the process of depressurization, which can provide theoretical guidance for the control of pressure drop when gas hydrate is produced