35 research outputs found
RĂ©alisation et caractĂ©risation des revĂȘtements Ă base magnĂ©sium Ă©laborĂ©s par projection Ă froid
Le procĂ©dĂ© de projection Ă froid a dĂ©montrĂ© ses avantages uniques dans la prĂ©paration de revĂȘtements mĂ©talliques, composites et cĂ©ramiques. Parmi ces revĂȘtements, ceux constituĂ©s de magnĂ©sium pur ou de composites Ă matrice mĂ©tallique Ă base de magnĂ©sium font partie des matĂ©riaux les plus prometteurs en raison de leur excellente rĂ©sistance spĂ©cifique. Pourtant, les mĂ©canismes de fabrication, par ce procĂ©dĂ© de projection, des revĂȘtements magnĂ©sium et composites Ă base de magnĂ©sium n'ont pas Ă©tĂ© Ă©tudiĂ©s. C est le sujet de cette thĂšse. Les recherches menĂ©es dans cette Ă©tude s articulent autour de plusieurs domaines, Ă savoir: La science des matĂ©riaux avec des Ă©tudes sur l effet de la granulomĂ©trie des particules de magnĂ©sium, l effet de la taille et de la teneur (15% vol. - 60 % vol.) des particules de renforcement (SiC) ; La mĂ©canique des fluides avec des modĂ©lisations de gĂ©omĂ©trie de buse, d Ă©coulement de gaz et des vitesses des particules de magnĂ©sium et alliage de magnĂ©sium (AZ91D) ; Les caractĂ©risations des dĂ©pĂŽts avec des analyses de microstructure et des mesures de microduretĂ©, d adhĂ©rence et de comportement au frottement des revĂȘtements;Les rĂ©sultats montrent que la projection Ă froid peut ĂȘtre utilisĂ©e pour fabriquer des revĂȘtements de magnĂ©sium purs ou composites sans aucune oxydation ou transformation de phase. La taille de ces particules doit rester dans une fourchette acceptable pour Ă©galer la vitesse critique (entre 653 m s-1 et 677 m s-1) permettant la dĂ©position. Concernant plus spĂ©cifiquement les rĂ©sultats sur les revĂȘtements de magnĂ©sium pur, le maximum de rendement de dĂ©pĂŽt est obtenu par projection d une poudre de granulomĂ©trie comprise entre 22 m et 64 m. L adhĂ©rence atteint 11.6 +- 0.5 MPa lorsque le substrat est prĂ©chauffĂ© Ă 200 oC. Pour le cas des revĂȘtements AZ91D, la construction du dĂ©pĂŽt s effectue par effet de verrouillage mĂ©canique. Le type de frottement observĂ© sur ces revĂȘtements est une usure adhĂ©sive. Dans les revĂȘtements composites d AZ91D SiC, la teneur en particules de renforcement SiC prĂ©sentes dans le dĂ©pĂŽt diminue avec leur taille dĂ» Ă l'effet onde de choc . Le rendement de dĂ©pĂŽt augmente avec la teneur en SiC de 15 vol.% Ă 30 vol.%, puis diminue au-delĂ de 30 vol%. Le type de frottement correspond Ă une usure par abrasion.Cold spraying has shown unique advantages in preparing coatings of metal, composite and ceramic. However, the deposition mechanism of magnesium and magnesium-based composite coatings fabricated using cold spraying was not researched although magnesium and metallic matrix composites based magnesium have drawn more and more attention due to their excellent specific strength. Therefore, the deposition mechanism of magnesium and magnesium-based composite coating has been studied in this study. The research carried out in this study involves several fields:Effect of the particle velocity of magnesium particles on the deposition efficiency, microstructure, microhardness and bonding strength of coatings; Effect of the particle size of magnesium particles on the deposition efficiency and microstructure of coatings;Effect of the substrate preheating on the microstructure, microhardness and bonding strength of coatings;Effect of the particle velocity of magnesium alloy (AZ91D) particles on the deposition efficiency, microstructure, and frictional behavior of coatings;Effect of the particle size of strengthening phrase (SiC) on the microstructure, bonding strength and frictional behavior of coatings;Effect of the particle content (15 vol.% - 60 vol.%) of strengthening phrase (SiC) on the microstructure, bonding strength and frictional behavior of coatings.The results show that cold spraying can be used to fabricate magnesium and magnesium-based coatings without any oxidation or phase transformation. The critical velocity of magnesium particles is 653 m s-1- 677 m s-1. Magnesium particles with a size too large or too small are not suitable to the deposition. The maximum of deposition efficiency of magnesium particles are obtained using the powder with a size range of 22-64 m. The maximum of bonding strength between magnesium coatings and substrates is 11.6 +- 0.5 MPa as the substrate is preheated at 200oC. The deposition of AZ91D coatings is due to the effect of mechanical interlocking. And the friction type of AZ91D coatings is adhesive wear. The friction type of AZ91D SiC composite coatings turn to be abrasive wear. The SiC content in composite coatings decreases as the SiC particle size decreases due to the effect of bow shock. The deposition efficiency of AZ91D and SiC mixed powder increases as the SiC content increases from 15 vol.% to 30 vol.%, and then decreases as the SiC content increases from 30 vol% to 60 vol.%.BELFORT-UTBM-SEVENANS (900942101) / SudocSudocFranceF
Preparation and characterization of magnesium coating deposited by cold spraying
Magnesium (Mg) and its alloys have a great potential as structural materials
due to their beneficial combination of high strength to weight ratio, high
thermal conductivity and good machinability. However, few literatures about Mg
coatings fabricated by cold spraying can be found. In this study, Mg coatings
were fabricated by cold spraying, and the microstructure, phase structure,
oxygen content and microhardness of the coating prepared under different main
gas temperatures were investigated. The critical velocity of the particle was
evaluated through numerical simulations. The particle deformation behavior and
bonding mechanism were discussed. The result of the oxygen content test shows
that the oxygen contents of the coatings did not increase comparing with that
of the feedstock powder. The simulation results show that the critical velocity
of Mg particles was in a range of 653 m/s to 677 m/s. The observation of the
coating fracture morphology shows that the formation of the coating was due to
the intensive plastic deformation and mechanical interlocking. The
microhardness of the coating increased with the increase of the main gas
temperature from 350oC to 450oC due to the decrease of the coating porosity.Comment: 20 pages, 9 figur
RĂ©alisation et caractĂ©risation des revĂȘtements Ă base magnĂ©sium Ă©laborĂ©s par projection Ă froid
Cold spraying has shown unique advantages in preparing coatings of metal, composite and ceramic. However, the deposition mechanism of magnesium and magnesium-based composite coatings fabricated using cold spraying was not researched although magnesium and metallic matrix composites based magnesium have drawn more and more attention due to their excellent specific strength. Therefore, the deposition mechanism of magnesium and magnesium-based composite coating has been studied in this study. The research carried out in this study involves several fields:Effect of the particle velocity of magnesium particles on the deposition efficiency, microstructure, microhardness and bonding strength of coatings; Effect of the particle size of magnesium particles on the deposition efficiency and microstructure of coatings;Effect of the substrate preheating on the microstructure, microhardness and bonding strength of coatings;Effect of the particle velocity of magnesium alloy (AZ91D) particles on the deposition efficiency, microstructure, and frictional behavior of coatings;Effect of the particle size of strengthening phrase (SiC) on the microstructure, bonding strength and frictional behavior of coatings;Effect of the particle content (15 vol.% - 60 vol.%) of strengthening phrase (SiC) on the microstructure, bonding strength and frictional behavior of coatings.The results show that cold spraying can be used to fabricate magnesium and magnesium-based coatings without any oxidation or phase transformation. The critical velocity of magnesium particles is 653 mâąs-1- 677 mâąs-1. Magnesium particles with a size too large or too small are not suitable to the deposition. The maximum of deposition efficiency of magnesium particles are obtained using the powder with a size range of 22-64 ÎŒm. The maximum of bonding strength between magnesium coatings and substrates is 11.6 ± 0.5 MPa as the substrate is preheated at 200oC. The deposition of AZ91D coatings is due to the effect of mechanical interlocking. And the friction type of AZ91D coatings is adhesive wear. The friction type of AZ91D â SiC composite coatings turn to be abrasive wear. The SiC content in composite coatings decreases as the SiC particle size decreases due to the effect of bow shock. The deposition efficiency of AZ91D and SiC mixed powder increases as the SiC content increases from 15 vol.% to 30 vol.%, and then decreases as the SiC content increases from 30 vol% to 60 vol.%.Le procĂ©dĂ© de projection Ă froid a dĂ©montrĂ© ses avantages uniques dans la prĂ©paration de revĂȘtements mĂ©talliques, composites et cĂ©ramiques. Parmi ces revĂȘtements, ceux constituĂ©s de magnĂ©sium pur ou de composites Ă matrice mĂ©tallique Ă base de magnĂ©sium font partie des matĂ©riaux les plus prometteurs en raison de leur excellente rĂ©sistance spĂ©cifique. Pourtant, les mĂ©canismes de fabrication, par ce procĂ©dĂ© de projection, des revĂȘtements magnĂ©sium et composites Ă base de magnĂ©sium n'ont pas Ă©tĂ© Ă©tudiĂ©s. Câest le sujet de cette thĂšse. Les recherches menĂ©es dans cette Ă©tude sâarticulent autour de plusieurs domaines, Ă savoir:La science des matĂ©riaux avec des Ă©tudes sur lâeffet de la granulomĂ©trie des particules de magnĂ©sium, lâeffet de la taille et de la teneur (15% vol. - 60 % vol.) des particules de renforcement (SiC) ;La mĂ©canique des fluides avec des modĂ©lisations de gĂ©omĂ©trie de buse, dâĂ©coulement de gaz et des vitesses des particules de magnĂ©sium et alliage de magnĂ©sium (AZ91D) ;Les caractĂ©risations des dĂ©pĂŽts avec des analyses de microstructure et des mesures de microduretĂ©, dâadhĂ©rence et de comportement au frottement des revĂȘtements;Les rĂ©sultats montrent que la projection Ă froid peut ĂȘtre utilisĂ©e pour fabriquer des revĂȘtements de magnĂ©sium purs ou composites sans aucune oxydation ou transformation de phase. La taille de ces particules doit rester dans une fourchette acceptable pour Ă©galer la vitesse critique (entre 653 mâąs-1 et 677 mâąs-1) permettant la dĂ©position. Concernant plus spĂ©cifiquement les rĂ©sultats sur les revĂȘtements de magnĂ©sium pur, le maximum de rendement de dĂ©pĂŽt est obtenu par projection dâune poudre de granulomĂ©trie comprise entre 22 ÎŒm et 64 ÎŒm. LâadhĂ©rence atteint 11.6 ± 0.5 MPa lorsque le substrat est prĂ©chauffĂ© Ă 200 oC. Pour le cas des revĂȘtements AZ91D, la construction du dĂ©pĂŽt sâeffectue par effet de verrouillage mĂ©canique. Le type de frottement observĂ© sur ces revĂȘtements est une usure adhĂ©sive. Dans les revĂȘtements composites dâAZ91D â SiC, la teneur en particules de renforcement SiC prĂ©sentes dans le dĂ©pĂŽt diminue avec leur taille dĂ» Ă l'effet «onde de choc». Le rendement de dĂ©pĂŽt augmente avec la teneur en SiC de 15 vol.% Ă 30 vol.%, puis diminue au-delĂ de 30 vol%. Le type de frottement correspond Ă une usure par abrasion
Production and characterization of magnesium-based coatings prepared by cold spraying
Le procĂ©dĂ© de projection Ă froid a dĂ©montrĂ© ses avantages uniques dans la prĂ©paration de revĂȘtements mĂ©talliques, composites et cĂ©ramiques. Parmi ces revĂȘtements, ceux constituĂ©s de magnĂ©sium pur ou de composites Ă matrice mĂ©tallique Ă base de magnĂ©sium font partie des matĂ©riaux les plus prometteurs en raison de leur excellente rĂ©sistance spĂ©cifique. Pourtant, les mĂ©canismes de fabrication, par ce procĂ©dĂ© de projection, des revĂȘtements magnĂ©sium et composites Ă base de magnĂ©sium n'ont pas Ă©tĂ© Ă©tudiĂ©s. Câest le sujet de cette thĂšse. Les recherches menĂ©es dans cette Ă©tude sâarticulent autour de plusieurs domaines, Ă savoir: La science des matĂ©riaux avec des Ă©tudes sur lâeffet de la granulomĂ©trie des particules de magnĂ©sium, lâeffet de la taille et de la teneur (15% vol. - 60 % vol.) des particules de renforcement (SiC) ; La mĂ©canique des fluides avec des modĂ©lisations de gĂ©omĂ©trie de buse, dâĂ©coulement de gaz et des vitesses des particules de magnĂ©sium et alliage de magnĂ©sium (AZ91D) ; Les caractĂ©risations des dĂ©pĂŽts avec des analyses de microstructure et des mesures de microduretĂ©, dâadhĂ©rence et de comportement au frottement des revĂȘtements;Les rĂ©sultats montrent que la projection Ă froid peut ĂȘtre utilisĂ©e pour fabriquer des revĂȘtements de magnĂ©sium purs ou composites sans aucune oxydation ou transformation de phase. La taille de ces particules doit rester dans une fourchette acceptable pour Ă©galer la vitesse critique (entre 653 mâąs-1 et 677 mâąs-1) permettant la dĂ©position. Concernant plus spĂ©cifiquement les rĂ©sultats sur les revĂȘtements de magnĂ©sium pur, le maximum de rendement de dĂ©pĂŽt est obtenu par projection dâune poudre de granulomĂ©trie comprise entre 22 ÎŒm et 64 ÎŒm. LâadhĂ©rence atteint 11.6 ± 0.5 MPa lorsque le substrat est prĂ©chauffĂ© Ă 200 oC. Pour le cas des revĂȘtements AZ91D, la construction du dĂ©pĂŽt sâeffectue par effet de verrouillage mĂ©canique. Le type de frottement observĂ© sur ces revĂȘtements est une usure adhĂ©sive. Dans les revĂȘtements composites dâAZ91D â SiC, la teneur en particules de renforcement SiC prĂ©sentes dans le dĂ©pĂŽt diminue avec leur taille dĂ» Ă l'effet «onde de choc». Le rendement de dĂ©pĂŽt augmente avec la teneur en SiC de 15 vol.% Ă 30 vol.%, puis diminue au-delĂ de 30 vol%. Le type de frottement correspond Ă une usure par abrasion.Cold spraying has shown unique advantages in preparing coatings of metal, composite and ceramic. However, the deposition mechanism of magnesium and magnesium-based composite coatings fabricated using cold spraying was not researched although magnesium and metallic matrix composites based magnesium have drawn more and more attention due to their excellent specific strength. Therefore, the deposition mechanism of magnesium and magnesium-based composite coating has been studied in this study. The research carried out in this study involves several fields:Effect of the particle velocity of magnesium particles on the deposition efficiency, microstructure, microhardness and bonding strength of coatings; Effect of the particle size of magnesium particles on the deposition efficiency and microstructure of coatings;Effect of the substrate preheating on the microstructure, microhardness and bonding strength of coatings;Effect of the particle velocity of magnesium alloy (AZ91D) particles on the deposition efficiency, microstructure, and frictional behavior of coatings;Effect of the particle size of strengthening phrase (SiC) on the microstructure, bonding strength and frictional behavior of coatings;Effect of the particle content (15 vol.% - 60 vol.%) of strengthening phrase (SiC) on the microstructure, bonding strength and frictional behavior of coatings.The results show that cold spraying can be used to fabricate magnesium and magnesium-based coatings without any oxidation or phase transformation. The critical velocity of magnesium particles is 653 mâąs-1- 677 mâąs-1. Magnesium particles with a size too large or too small are not suitable to the deposition. The maximum of deposition efficiency of magnesium particles are obtained using the powder with a size range of 22-64 ÎŒm. The maximum of bonding strength between magnesium coatings and substrates is 11.6 ± 0.5 MPa as the substrate is preheated at 200oC. The deposition of AZ91D coatings is due to the effect of mechanical interlocking. And the friction type of AZ91D coatings is adhesive wear. The friction type of AZ91D â SiC composite coatings turn to be abrasive wear. The SiC content in composite coatings decreases as the SiC particle size decreases due to the effect of bow shock. The deposition efficiency of AZ91D and SiC mixed powder increases as the SiC content increases from 15 vol.% to 30 vol.%, and then decreases as the SiC content increases from 30 vol% to 60 vol.%
Numerical and Experimental Investigation on Bonding Behavior of Cold Sprayed Porous WC-17Co Particles onto Different Substrates
Cold sprayed WC-Co metal matrix composite coatings have shown great potential in wear-resistance applications. This work aims to use experimental and numerical methods to clarify the deposition and particleâsubstrate bonding behavior of a single porous WC-17Co particle onto various substrates. To achieve this objective, porous WC-17Co particles were used as the feedstock; soft Al 2024 (Al alloy) and hard stainless steel 316 (SS) were used as the substrates. The experimental results revealed that brittle WC-Co particles tended to remain intact after depositing on a soft Al alloy substrate, but underwent serious fracture when impacting on a hard SS substrate. Further results indicated that the high energy dissipation and the consequent high stress concentration in the WC-Co particle was the main reason for inducing the particle fracture. In addition, two different mechanical interlocking mechanisms were identified during the WC-Co particle deposition process (namely WC reinforcement interlock and WC-Co particle interlock), dominating the particle-substrate bonding. A soft Al alloy substrate resulted in better interlocking than a hard SS substrate, thereby the corresponding particle bonding ratio was also much higher
Numerical and Experimental Investigation on Bonding Behavior of Cold Sprayed Porous WC-17Co Particles onto Different Substrates
Cold sprayed WC-Co metal matrix composite coatings have shown great potential in wear-resistance applications. This work aims to use experimental and numerical methods to clarify the deposition and particleâsubstrate bonding behavior of a single porous WC-17Co particle onto various substrates. To achieve this objective, porous WC-17Co particles were used as the feedstock; soft Al 2024 (Al alloy) and hard stainless steel 316 (SS) were used as the substrates. The experimental results revealed that brittle WC-Co particles tended to remain intact after depositing on a soft Al alloy substrate, but underwent serious fracture when impacting on a hard SS substrate. Further results indicated that the high energy dissipation and the consequent high stress concentration in the WC-Co particle was the main reason for inducing the particle fracture. In addition, two different mechanical interlocking mechanisms were identified during the WC-Co particle deposition process (namely WC reinforcement interlock and WC-Co particle interlock), dominating the particle-substrate bonding. A soft Al alloy substrate resulted in better interlocking than a hard SS substrate, thereby the corresponding particle bonding ratio was also much higher
Cold-Sprayed Metal Coatings with Nanostructure
Cold spray is a solid-state coating deposition technology developed in the 1980s. In comparison with conventional thermal spray processes, cold spray can retain the original properties of feedstock, prevent the adverse influence on the underlying substrate materials, and produce very thick coatings. Coatings with nanostructure offer the potential for significant improvements in physical and mechanical properties as compared with conventional non-nanostructured coatings. Cold spray has also demonstrated great capability to produce coatings with nanostructure. This paper is aimed at providing a comprehensive overview of cold-sprayed metal coatings with nanostructure. A brief introduction of the cold spray technology is provided first. The nanocrystallization phenomenon in the conventional cold-sprayed metal coatings is then addressed. Thereafter, focus is switched to the microstructure and properties of the cold-sprayed nanocrystalline metal coatings, and the cold-sprayed nanomaterial-reinforced metal matrix composite (MMC) coatings. At the end, summary and future perspectives of the cold spray technology in producing metal coatings with nanostructure are concluded
Numerical and Experimental Investigation on Bonding Behavior of Cold Sprayed Porous WC-17Co Particles onto Different Substrates
Cold sprayed WC-Co metal matrix composite coatings have shown great potential in wear-resistance applications. This work aims to use experimental and numerical methods to clarify the deposition and particle-substrate bonding behavior of a single porous WC-17Co particle onto various substrates. To achieve this objective, porous WC-17Co particles were used as the feedstock; soft Al 2024 (Al alloy) and hard stainless steel 316 (SS) were used as the substrates. The experimental results revealed that brittle WC-Co particles tended to remain intact after depositing on a soft Al alloy substrate, but underwent serious fracture when impacting on a hard SS substrate. Further results indicated that the high energy dissipation and the consequent high stress concentration in the WC-Co particle was the main reason for inducing the particle fracture. In addition, two different mechanical interlocking mechanisms were identified during the WC-Co particle deposition process (namely WC reinforcement interlock and WC-Co particle interlock), dominating the particle-substrate bonding. A soft Al alloy substrate resulted in better interlocking than a hard SS substrate, thereby the corresponding particle bonding ratio was also much higher
Numerical and Experimental Investigation on Bonding Behavior of Cold Sprayed Porous WC-17Co Particles onto Different Substrates
Cold sprayed WC-Co metal matrix composite coatings have shown great potential in wear-resistance applications. This work aims to use experimental and numerical methods to clarify the deposition and particle-substrate bonding behavior of a single porous WC-17Co particle onto various substrates. To achieve this objective, porous WC-17Co particles were used as the feedstock; soft Al 2024 (Al alloy) and hard stainless steel 316 (SS) were used as the substrates. The experimental results revealed that brittle WC-Co particles tended to remain intact after depositing on a soft Al alloy substrate, but underwent serious fracture when impacting on a hard SS substrate. Further results indicated that the high energy dissipation and the consequent high stress concentration in the WC-Co particle was the main reason for inducing the particle fracture. In addition, two different mechanical interlocking mechanisms were identified during the WC-Co particle deposition process (namely WC reinforcement interlock and WC-Co particle interlock), dominating the particle-substrate bonding. A soft Al alloy substrate resulted in better interlocking than a hard SS substrate, thereby the corresponding particle bonding ratio was also much higher