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David L Dl Bourell - One of the best experts on this subject based on the ideXlab platform.

  • Sintering in Laser Sintering
    JOM, 2016
    Co-Authors: David L Dl Bourell
    Abstract:

    Laser sintering is a popular additive manufacturing technology, particularly for service parts. Invented by C. Deckard in the mid-1980s, the approach of using a laser to densify a powder bed selectively has been extensively researched and has been applied to metals, ceramics, polymers and composites. In the traditional powder-metallurgical sense, sintering involves solid-state atomic transport resulting in neck formation and eventual densification in a powder mass. The use of the term “sintering” as a descriptive term for the powder-bed additive manufacturing process has been problematical to the technical community, because the predominant densification mechanism has been shown for most applications to be melting and reflow. The term has perpetuated as a name for the additive manufacturing process, at least for polymers. The technical term “sintering” is accurately associated with laser sintering insofar as powder pre-processing and part post-processing are concerned. It may also be used to describe formation of “part cake”. This paper describes the circumstances surrounding the coining of the term, “laser sintering” and provides some examples of how sintering is used in pre- and post-processing.

  • Producing metal parts with selective laser sintering/hot isostatic pressing
    JOM, 1999
    Co-Authors: Suman Das, Martin Wohlert, Joseph Jr Beaman, David L Dl Bourell
    Abstract:

    Selective laser sintering/hot isostatic pressing is a hybrid direct laser fabrication method that combines the strengths of both processes. Selective laser sintering can produce complexly shaped metal components with an integral, gas-impermeable skin. These components can then be directly post-processed to full density by containerless hot isostatic pressing. The use of the hybrid fabrication method, envisioned as a rapid, low-cost replacement for conventional metal-can hot isostatic pressing, is currently being studied for alloy 625 and Ti-6Al-4V alloys. The microstructure and mechanical properties of selective-laser-sintering processed and hot isostatically pressed post-processed material compare well with those of conventionally processed material.

  • producing metal parts with selective laser sintering hot isostatic pressing
    JOM, 1998
    Co-Authors: Martin Wohlert, David L Dl Bourell, Joseph Jr Beaman
    Abstract:

    Selective laser sintering/hot isostatic pressing is a hybrid direct laser fabrication method that combines the strengths of both processes. Selective laser sintering can produce complexly shaped metal components with an integral, gas-impermeable skin. These components can then be directly post-processed to full density by containerless hot isostatic pressing. The use of the hybrid fabrication method, envisioned as a rapid, low-cost replacement for conventional metal-can hot isostatic pressing, is currently being studied for alloy 625 and Ti-6Al-4V alloys. The micro-structure and mechanical properties of selective-laser-sintering processed and hot isostatically pressed post-processed material compare well with those of conventionally processed material.

Ulrich S Schubert - One of the best experts on this subject based on the ideXlab platform.

  • ink jet printing and microwave sintering of conductive silver tracks
    Advanced Materials, 2006
    Co-Authors: Jolke Perelaer, De Bj Berendjan Gans, Ulrich S Schubert
    Abstract:

    Printing techniques, such as ink-jet printing, are interesting alternatives to conventional photolithography for the production of electronic devices. The advantages of printing include the ease of mass production, low cost, and flexibility. Compared to other printing techniques (e.g., screen printing), ink-jet printing does not offer the same production speed. However, the unprecedented flexibility of ink-jet printing makes it very well suited for rapid prototyping applications. In addition, it allows the use of inviscid fluids, such as dilute polymer solutions or suspensions without added binders. A typical application involves the ink-jet printing of conductive tracks, for example, by using inks based on (in)organic silver or copper precursors. The precursor is reduced to the corresponding metal via a post-printing thermal annealing step. In most cases, however, the ink is a dispersion of noble-metal nanoparticles, usually silver or gold. A sintering step is necessary to render the tracks conductive. The use of nanoparticles reduces the sintering temperature due to their high surface to volume ratio. In the past, two different techniques have been used to sinter printed nanoparticle structures. Conventional radiation– conduction–convection heating is the most commonly used method, wherein the sintering temperatures are typically above 200 °C. Therefore many potentially interesting substrate materials, such as thermoplastic polymers or paper, cannot be used. In fact, one of the very few, if not the only organic substrate that can be used is (expensive) polyimide (PI). The long sintering times required—usually 60 min or more— also imply that the technique is not feasible for fast industrial production. As an alternative, a laser sintering method was developed. The laser follows the conductive tracks and sinters these selectively, without affecting the substrate. However, this method is costly and complex from a technical point of view. Thus, there is a clear need for a fast, simple, and costeffective technique that would allow the sintering of the printed structures by the selective heating of only the printed components. Microwave heating fulfills these requirements. Microwave heating is widely used for the sintering of dielectric materials and in synthetic chemistry. It offers advantages such as uniform, fast, and volumetric heating. Microwave radiation is absorbed due to coupling with charge carriers or rotating dipoles. The absorbed power per unit volume P is,

  • Ink‐jet Printing and Microwave Sintering of Conductive Silver Tracks
    Advanced Materials, 2006
    Co-Authors: Jolke Perelaer, De Bj Berend-jan Gans, Ulrich S Schubert
    Abstract:

    Printing techniques, such as ink-jet printing, are interesting alternatives to conventional photolithography for the production of electronic devices. The advantages of printing include the ease of mass production, low cost, and flexibility. Compared to other printing techniques (e.g., screen printing), ink-jet printing does not offer the same production speed. However, the unprecedented flexibility of ink-jet printing makes it very well suited for rapid prototyping applications. In addition, it allows the use of inviscid fluids, such as dilute polymer solutions or suspensions without added binders. A typical application involves the ink-jet printing of conductive tracks, for example, by using inks based on (in)organic silver or copper precursors. The precursor is reduced to the corresponding metal via a post-printing thermal annealing step. In most cases, however, the ink is a dispersion of noble-metal nanoparticles, usually silver or gold. A sintering step is necessary to render the tracks conductive. The use of nanoparticles reduces the sintering temperature due to their high surface to volume ratio. In the past, two different techniques have been used to sinter printed nanoparticle structures. Conventional radiation– conduction–convection heating is the most commonly used method, wherein the sintering temperatures are typically above 200 °C. Therefore many potentially interesting substrate materials, such as thermoplastic polymers or paper, cannot be used. In fact, one of the very few, if not the only organic substrate that can be used is (expensive) polyimide (PI). The long sintering times required—usually 60 min or more— also imply that the technique is not feasible for fast industrial production. As an alternative, a laser sintering method was developed. The laser follows the conductive tracks and sinters these selectively, without affecting the substrate. However, this method is costly and complex from a technical point of view. Thus, there is a clear need for a fast, simple, and costeffective technique that would allow the sintering of the printed structures by the selective heating of only the printed components. Microwave heating fulfills these requirements. Microwave heating is widely used for the sintering of dielectric materials and in synthetic chemistry. It offers advantages such as uniform, fast, and volumetric heating. Microwave radiation is absorbed due to coupling with charge carriers or rotating dipoles. The absorbed power per unit volume P is,

Tetsuya Uda - One of the best experts on this subject based on the ideXlab platform.

  • fabrication of protonic ceramic fuel cells via infiltration with ni nanoparticles a new strategy to suppress nio diffusion increase open circuit voltage
    Solid State Ionics, 2020
    Co-Authors: Donglin Han, Masatoshi Majima, Akiko Kuramitsu, Takayuki Onishi, Yohei Noda, Tetsuya Uda
    Abstract:

    Abstract Presently, most of the cells using BaZr0.8Y0.2O3-δ (BZY20) electrolyte were prepared by a co-sintering process performed between 1400 and 1600 °C. However, during the co-sintering process, Ni diffuses from the anode substrate into the BZY20 electrolyte layer, resulting in the decrease in both the proton conductivity and transport number of proton conduction. Furthermore, second phases like BaY2NiO5 form in the electrolyte, and the Y content decreases dramatically to about 5-6 at.%. All these issues indicate that the co-sintering process will restrict the further development of the BZY20 electrolyte-based cells, and some new method is necessary. In this work, we report a new cell fabrication method by infiltrating ink containing Ni nanoparticles into preliminarily sintered BZY20 cell with a porous layer, to suppress the unfavorable Ni diffusion and Y loss in the BZY20 electrolyte, which are problems in the conventional co-sintering process. This process is easy in manipulation and low in cost, and most importantly, makes the cell using the pristine BZY20 electrolyte possible. However, this approach needs to be improved or optimized by thinning the electrolyte, improving the adhesion between the electrolyte and electrode, and optimizing the anode structure.

  • detrimental effect of sintering additives on conducting ceramics yttrium doped barium zirconate
    Chemsuschem, 2018
    Co-Authors: Donglin Han, Shigeaki Uemura, Chihiro Hiraiwa, Masatoshi Majima, Tetsuya Uda
    Abstract:

    Y-doped BaZrO3 (BZY) is currently the most promising proton-conductive ceramic-type electrolyte for application in electrochemical devices, including fuel cells and electrolyzer cells. However, owing to its refractory nature, sintering additives, such as NiO, CuO, or ZnO are commonly added to reduce its high sintering temperature from 1600 °C to approximately 1400 °C. Even without deliberately adding a sintering additive, the NiO anode substrate provides another source of the sintering additive; during the co-sintering process, NiO diffuses from the anode into the BZY electrolyte layer. In this work, a systematic study of the effect of NiO, CuO, and ZnO on the electroconductive properties of BaZr0.8 Y0.2 O3-δ (BZY20) is conducted. The results revealed that the addition of NiO, CuO, or ZnO into BZY20 not only degraded the electrical conductivity but also resulted in enhancement of the hole conduction. Removal of these sintering additives can be realized by post-annealing in hydrogen at a mild temperature of 700 °C, but it is kinetically very slow. Therefore, the addition of NiO, CuO, and ZnO is detrimental to the electroconductive properties of BZY20, and significantly restrict its application as an electrolyte. The development of new sintering additives, new anode catalysts, or new methods for preparing BZY electrolyte-based cells is urgently needed.

Donglin Han - One of the best experts on this subject based on the ideXlab platform.

  • fabrication of protonic ceramic fuel cells via infiltration with ni nanoparticles a new strategy to suppress nio diffusion increase open circuit voltage
    Solid State Ionics, 2020
    Co-Authors: Donglin Han, Masatoshi Majima, Akiko Kuramitsu, Takayuki Onishi, Yohei Noda, Tetsuya Uda
    Abstract:

    Abstract Presently, most of the cells using BaZr0.8Y0.2O3-δ (BZY20) electrolyte were prepared by a co-sintering process performed between 1400 and 1600 °C. However, during the co-sintering process, Ni diffuses from the anode substrate into the BZY20 electrolyte layer, resulting in the decrease in both the proton conductivity and transport number of proton conduction. Furthermore, second phases like BaY2NiO5 form in the electrolyte, and the Y content decreases dramatically to about 5-6 at.%. All these issues indicate that the co-sintering process will restrict the further development of the BZY20 electrolyte-based cells, and some new method is necessary. In this work, we report a new cell fabrication method by infiltrating ink containing Ni nanoparticles into preliminarily sintered BZY20 cell with a porous layer, to suppress the unfavorable Ni diffusion and Y loss in the BZY20 electrolyte, which are problems in the conventional co-sintering process. This process is easy in manipulation and low in cost, and most importantly, makes the cell using the pristine BZY20 electrolyte possible. However, this approach needs to be improved or optimized by thinning the electrolyte, improving the adhesion between the electrolyte and electrode, and optimizing the anode structure.

  • detrimental effect of sintering additives on conducting ceramics yttrium doped barium zirconate
    Chemsuschem, 2018
    Co-Authors: Donglin Han, Shigeaki Uemura, Chihiro Hiraiwa, Masatoshi Majima, Tetsuya Uda
    Abstract:

    Y-doped BaZrO3 (BZY) is currently the most promising proton-conductive ceramic-type electrolyte for application in electrochemical devices, including fuel cells and electrolyzer cells. However, owing to its refractory nature, sintering additives, such as NiO, CuO, or ZnO are commonly added to reduce its high sintering temperature from 1600 °C to approximately 1400 °C. Even without deliberately adding a sintering additive, the NiO anode substrate provides another source of the sintering additive; during the co-sintering process, NiO diffuses from the anode into the BZY electrolyte layer. In this work, a systematic study of the effect of NiO, CuO, and ZnO on the electroconductive properties of BaZr0.8 Y0.2 O3-δ (BZY20) is conducted. The results revealed that the addition of NiO, CuO, or ZnO into BZY20 not only degraded the electrical conductivity but also resulted in enhancement of the hole conduction. Removal of these sintering additives can be realized by post-annealing in hydrogen at a mild temperature of 700 °C, but it is kinetically very slow. Therefore, the addition of NiO, CuO, and ZnO is detrimental to the electroconductive properties of BZY20, and significantly restrict its application as an electrolyte. The development of new sintering additives, new anode catalysts, or new methods for preparing BZY electrolyte-based cells is urgently needed.

Jolke Perelaer - One of the best experts on this subject based on the ideXlab platform.

  • ink jet printing and microwave sintering of conductive silver tracks
    Advanced Materials, 2006
    Co-Authors: Jolke Perelaer, De Bj Berendjan Gans, Ulrich S Schubert
    Abstract:

    Printing techniques, such as ink-jet printing, are interesting alternatives to conventional photolithography for the production of electronic devices. The advantages of printing include the ease of mass production, low cost, and flexibility. Compared to other printing techniques (e.g., screen printing), ink-jet printing does not offer the same production speed. However, the unprecedented flexibility of ink-jet printing makes it very well suited for rapid prototyping applications. In addition, it allows the use of inviscid fluids, such as dilute polymer solutions or suspensions without added binders. A typical application involves the ink-jet printing of conductive tracks, for example, by using inks based on (in)organic silver or copper precursors. The precursor is reduced to the corresponding metal via a post-printing thermal annealing step. In most cases, however, the ink is a dispersion of noble-metal nanoparticles, usually silver or gold. A sintering step is necessary to render the tracks conductive. The use of nanoparticles reduces the sintering temperature due to their high surface to volume ratio. In the past, two different techniques have been used to sinter printed nanoparticle structures. Conventional radiation– conduction–convection heating is the most commonly used method, wherein the sintering temperatures are typically above 200 °C. Therefore many potentially interesting substrate materials, such as thermoplastic polymers or paper, cannot be used. In fact, one of the very few, if not the only organic substrate that can be used is (expensive) polyimide (PI). The long sintering times required—usually 60 min or more— also imply that the technique is not feasible for fast industrial production. As an alternative, a laser sintering method was developed. The laser follows the conductive tracks and sinters these selectively, without affecting the substrate. However, this method is costly and complex from a technical point of view. Thus, there is a clear need for a fast, simple, and costeffective technique that would allow the sintering of the printed structures by the selective heating of only the printed components. Microwave heating fulfills these requirements. Microwave heating is widely used for the sintering of dielectric materials and in synthetic chemistry. It offers advantages such as uniform, fast, and volumetric heating. Microwave radiation is absorbed due to coupling with charge carriers or rotating dipoles. The absorbed power per unit volume P is,

  • Ink‐jet Printing and Microwave Sintering of Conductive Silver Tracks
    Advanced Materials, 2006
    Co-Authors: Jolke Perelaer, De Bj Berend-jan Gans, Ulrich S Schubert
    Abstract:

    Printing techniques, such as ink-jet printing, are interesting alternatives to conventional photolithography for the production of electronic devices. The advantages of printing include the ease of mass production, low cost, and flexibility. Compared to other printing techniques (e.g., screen printing), ink-jet printing does not offer the same production speed. However, the unprecedented flexibility of ink-jet printing makes it very well suited for rapid prototyping applications. In addition, it allows the use of inviscid fluids, such as dilute polymer solutions or suspensions without added binders. A typical application involves the ink-jet printing of conductive tracks, for example, by using inks based on (in)organic silver or copper precursors. The precursor is reduced to the corresponding metal via a post-printing thermal annealing step. In most cases, however, the ink is a dispersion of noble-metal nanoparticles, usually silver or gold. A sintering step is necessary to render the tracks conductive. The use of nanoparticles reduces the sintering temperature due to their high surface to volume ratio. In the past, two different techniques have been used to sinter printed nanoparticle structures. Conventional radiation– conduction–convection heating is the most commonly used method, wherein the sintering temperatures are typically above 200 °C. Therefore many potentially interesting substrate materials, such as thermoplastic polymers or paper, cannot be used. In fact, one of the very few, if not the only organic substrate that can be used is (expensive) polyimide (PI). The long sintering times required—usually 60 min or more— also imply that the technique is not feasible for fast industrial production. As an alternative, a laser sintering method was developed. The laser follows the conductive tracks and sinters these selectively, without affecting the substrate. However, this method is costly and complex from a technical point of view. Thus, there is a clear need for a fast, simple, and costeffective technique that would allow the sintering of the printed structures by the selective heating of only the printed components. Microwave heating fulfills these requirements. Microwave heating is widely used for the sintering of dielectric materials and in synthetic chemistry. It offers advantages such as uniform, fast, and volumetric heating. Microwave radiation is absorbed due to coupling with charge carriers or rotating dipoles. The absorbed power per unit volume P is,