2025
S. Bhandari; O. Hanzel; M. Kermani; V. M. Sglavo; M. Biesuz; G. Franchin
Rapid debinding and sintering of alumina ceramics fabricated by direct ink writing Journal Article
In: Journal of the European Ceramic Society, vol. 45, no. 5, pp. 117144, 2025, ISSN: 0955-2219.
Abstract | Links | BibTeX | Tags: Additive Manufacturing
@article{BHANDARI2025117144,
title = {Rapid debinding and sintering of alumina ceramics fabricated by direct ink writing},
author = {S. Bhandari and O. Hanzel and M. Kermani and V. M. Sglavo and M. Biesuz and G. Franchin},
url = {https://www.sciencedirect.com/science/article/pii/S0955221924010173},
doi = {https://doi.org/10.1016/j.jeurceramsoc.2024.117144},
issn = {0955-2219},
year = {2025},
date = {2025-01-01},
urldate = {2025-01-01},
journal = {Journal of the European Ceramic Society},
volume = {45},
number = {5},
pages = {117144},
abstract = {Direct ink writing (DIW) is a widely used additive manufacturing technique to fabricate complex-shaped ceramics. Unlike vat photopolymerization or fused filament fabrication, the limited amount of binder in DIW facilitates rapid debinding. In this study, alumina inks with suitable rheology were prepared with two different ceramic loadings (42.8 vol% and 48.1 vol%). Subsequently, log-pile structures were printed using two different nozzle diameters (0.41 mm and 0.84 mm). The fabricated samples were dried at room temperature and subjected to different rapid sintering procedures: ultra-fast high temperature sintering (UHS), pressureless spark plasma sintering (PSPS) and fast-firing (FF). Both UHS and PSPS successfully densified the samples in Ar without any defects. Conversely, the fast-firing in air resulted in some cracks, with the intensity of failures increasing with the nozzle size. UHS and PSPS allowed for nearly fully dense materials with refined microstructure which are not achievable by conventional heating.},
keywords = {Additive Manufacturing},
pubstate = {published},
tppubtype = {article}
}
Direct ink writing (DIW) is a widely used additive manufacturing technique to fabricate complex-shaped ceramics. Unlike vat photopolymerization or fused filament fabrication, the limited amount of binder in DIW facilitates rapid debinding. In this study, alumina inks with suitable rheology were prepared with two different ceramic loadings (42.8 vol% and 48.1 vol%). Subsequently, log-pile structures were printed using two different nozzle diameters (0.41 mm and 0.84 mm). The fabricated samples were dried at room temperature and subjected to different rapid sintering procedures: ultra-fast high temperature sintering (UHS), pressureless spark plasma sintering (PSPS) and fast-firing (FF). Both UHS and PSPS successfully densified the samples in Ar without any defects. Conversely, the fast-firing in air resulted in some cracks, with the intensity of failures increasing with the nozzle size. UHS and PSPS allowed for nearly fully dense materials with refined microstructure which are not achievable by conventional heating.
S. Bhandari; G. Vajpayee; L. Lemos Silva; M. Hinterstein; G. Franchin; P. Colombo
A review on additive manufacturing of piezoelectric ceramics: From feedstock development to properties of sintered parts Journal Article
In: Materials Science and Engineering: R: Reports, vol. 162, pp. 100877, 2025, ISSN: 0927-796X.
Abstract | Links | BibTeX | Tags: Additive Manufacturing
@article{BHANDARI2025100877,
title = {A review on additive manufacturing of piezoelectric ceramics: From feedstock development to properties of sintered parts},
author = {S. Bhandari and G. Vajpayee and L. Lemos Silva and M. Hinterstein and G. Franchin and P. Colombo},
url = {https://www.sciencedirect.com/science/article/pii/S0927796X24001074},
doi = {https://doi.org/10.1016/j.mser.2024.100877},
issn = {0927-796X},
year = {2025},
date = {2025-01-01},
urldate = {2025-01-01},
journal = {Materials Science and Engineering: R: Reports},
volume = {162},
pages = {100877},
abstract = {Piezoelectric ceramics are extensively used in several engineering applications in the field of sensors, actuators, energy harvesting, biomedical, and many more. Traditional ways of manufacturing piezoelectric devices result in better piezoelectric/ferroelectric performance. However, they are restricted to only simple shapes. With the widespread influence of additive manufacturing (AM), it is now possible to fabricate complex structures which were not possible by conventional technologies. In order to fabricate such complex structures with precision, it is necessary to understand in detail the factors influencing the feedstock preparation and the challenges associated with different AM technologies. With an emphasis on the most commonly used AM techniques (direct ink writing, fused filament fabrication, vat photopolymerization, binder jetting, and selective laser sintering) for fabricating ceramic parts, this review paper intends to provide a deep insight into the factors affecting the feedstock preparation as well as post-processing conditions required to develop a high-performance piezoelectric device. The summarized tables detailing the various piezoelectric ceramic compositions and additives or ingredients used in formulating a printable feedstock, along with the optimum printing and post-processing conditions, will aid the readers in developing their own printable formulations and determining the best post-processing parameters to achieve the best performance out of the fabricated piezoelectric device. The advantages and disadvantages of the AM technologies are analyzed with specific reference to piezoceramic materials and the remaining challenges that require further research are emphasized. Furthermore, with the ongoing and continuous developments in additive manufacturing of piezoelectric materials, it is expected that such advancements will progressively transition towards commercialization, with the ultimate goal of widely incorporating additively manufactured devices into practical applications.},
keywords = {Additive Manufacturing},
pubstate = {published},
tppubtype = {article}
}
Piezoelectric ceramics are extensively used in several engineering applications in the field of sensors, actuators, energy harvesting, biomedical, and many more. Traditional ways of manufacturing piezoelectric devices result in better piezoelectric/ferroelectric performance. However, they are restricted to only simple shapes. With the widespread influence of additive manufacturing (AM), it is now possible to fabricate complex structures which were not possible by conventional technologies. In order to fabricate such complex structures with precision, it is necessary to understand in detail the factors influencing the feedstock preparation and the challenges associated with different AM technologies. With an emphasis on the most commonly used AM techniques (direct ink writing, fused filament fabrication, vat photopolymerization, binder jetting, and selective laser sintering) for fabricating ceramic parts, this review paper intends to provide a deep insight into the factors affecting the feedstock preparation as well as post-processing conditions required to develop a high-performance piezoelectric device. The summarized tables detailing the various piezoelectric ceramic compositions and additives or ingredients used in formulating a printable feedstock, along with the optimum printing and post-processing conditions, will aid the readers in developing their own printable formulations and determining the best post-processing parameters to achieve the best performance out of the fabricated piezoelectric device. The advantages and disadvantages of the AM technologies are analyzed with specific reference to piezoceramic materials and the remaining challenges that require further research are emphasized. Furthermore, with the ongoing and continuous developments in additive manufacturing of piezoelectric materials, it is expected that such advancements will progressively transition towards commercialization, with the ultimate goal of widely incorporating additively manufactured devices into practical applications.
2024
S. M. Carturan; H. Skliarova; G. Franchin; G. Bombardelli; A. Zanini; F. E. P. Andrades; J. C. Delgado Alvarez; S. Moretto; G. Maggioni; W. Raniero; D. Maniglio; A. P. Caricato; A. Quaranta
Additive manufacturing of high-performance, flexible 3D siloxane-based scintillators through the sol-gel route Journal Article
In: Applied Materials Today, vol. 39, 2024, ISSN: 2352-9407.
Links | BibTeX | Tags: Additive Manufacturing
@article{Carturan2024,
title = {Additive manufacturing of high-performance, flexible 3D siloxane-based scintillators through the sol-gel route},
author = {S. M. Carturan and H. Skliarova and G. Franchin and G. Bombardelli and A. Zanini and F. E. P. Andrades and J. C. Delgado Alvarez and S. Moretto and G. Maggioni and W. Raniero and D. Maniglio and A. P. Caricato and A. Quaranta},
doi = {10.1016/j.apmt.2024.102313},
issn = {2352-9407},
year = {2024},
date = {2024-08-00},
urldate = {2024-08-00},
journal = {Applied Materials Today},
volume = {39},
publisher = {Elsevier BV},
keywords = {Additive Manufacturing},
pubstate = {published},
tppubtype = {article}
}
A. Zanini; P. Amador Celdran; O. Walter; S. M. Carturan; J. Boshoven; A. Bulgheroni; L. Biasetto; M. Manzolaro; R. Eloirdi; S. Corradetti; G. Franchin
First Structured Uranium‐Based Monoliths Produced via Vat Photopolymerization for Nuclear Applications Journal Article
In: Adv Funct Materials, 2024, ISSN: 1616-3028.
Abstract | Links | BibTeX | Tags: Additive Manufacturing
@article{Zanini2024,
title = {First Structured Uranium‐Based Monoliths Produced via Vat Photopolymerization for Nuclear Applications},
author = {A. Zanini and P. Amador Celdran and O. Walter and S. M. Carturan and J. Boshoven and A. Bulgheroni and L. Biasetto and M. Manzolaro and R. Eloirdi and S. Corradetti and G. Franchin},
doi = {10.1002/adfm.202406916},
issn = {1616-3028},
year = {2024},
date = {2024-06-20},
urldate = {2024-06-20},
journal = {Adv Funct Materials},
publisher = {Wiley},
abstract = {Uranium plays an unquestionable role in the framework of nuclear physics, biology, and radiopharmacy. Moreover, uranyl ion UO2 2+ offers an immense variety of applications due to the unique photosensitivity of its complexes. The excited state of uranyl cation is indeed accessible under ultraviolet‐visible (UV–vis) light, readily producing radical species UO2 2+ upon light irradiation. Herein, an innovative synthesis protocol is presented to explore the use of uranyl cations as photocatalyst systems for photocurable sol–gel‐based formulations, coupling the photochemical reactions of uranyl cations with photopolymerization‐based additive manufacturing processes. Additive manufacturing has nowadays revolutionized the production of complex structures with arbitrary geometries and has opened up enticing opportunities for innovative technological breakthroughs and highly tailorable systems. The fabrication of micro‐architected components is shown via vat photopolymerization, namely, the Digital Light Processing technique, and ‐3D) printed parts are converted into uranium dicarbide (UC2)/carbon nanocomposite upon carbothermal reduction. This uranyl‐mediated additive manufacturing process constitutes the first application of the synergistic role of uranyl motifs in a photopolymer platform, demonstrating for the first time the possibility to directly pattern uranium‐based materials in complex structures.},
keywords = {Additive Manufacturing},
pubstate = {published},
tppubtype = {article}
}
Uranium plays an unquestionable role in the framework of nuclear physics, biology, and radiopharmacy. Moreover, uranyl ion UO2 2+ offers an immense variety of applications due to the unique photosensitivity of its complexes. The excited state of uranyl cation is indeed accessible under ultraviolet‐visible (UV–vis) light, readily producing radical species UO2 2+ upon light irradiation. Herein, an innovative synthesis protocol is presented to explore the use of uranyl cations as photocatalyst systems for photocurable sol–gel‐based formulations, coupling the photochemical reactions of uranyl cations with photopolymerization‐based additive manufacturing processes. Additive manufacturing has nowadays revolutionized the production of complex structures with arbitrary geometries and has opened up enticing opportunities for innovative technological breakthroughs and highly tailorable systems. The fabrication of micro‐architected components is shown via vat photopolymerization, namely, the Digital Light Processing technique, and ‐3D) printed parts are converted into uranium dicarbide (UC2)/carbon nanocomposite upon carbothermal reduction. This uranyl‐mediated additive manufacturing process constitutes the first application of the synergistic role of uranyl motifs in a photopolymer platform, demonstrating for the first time the possibility to directly pattern uranium‐based materials in complex structures.
S. Bhandari; O. Hanzel; P. Veteška; M. Janek; E. De Bona; V. M. Sglavo; M. Biesuz; G. Franchin
From rapid prototyping to rapid firing: on the feasibility of high‐speed production for complex BaTiO3 components Journal Article
In: J Am Ceram Soc., 2024, ISSN: 1551-2916.
Abstract | Links | BibTeX | Tags: Additive Manufacturing
@article{Bhandari2024,
title = {From rapid prototyping to rapid firing: on the feasibility of high‐speed production for complex BaTiO3 components},
author = {S. Bhandari and O. Hanzel and P. Veteška and M. Janek and E. De Bona and V. M. Sglavo and M. Biesuz and G. Franchin},
doi = {10.1111/jace.19950},
issn = {1551-2916},
year = {2024},
date = {2024-06-14},
urldate = {2024-06-14},
journal = {J Am Ceram Soc.},
publisher = {Wiley},
abstract = {Direct ink writing (DIW) is an attractive additive manufacturing (AM) technology because of its simplicity, production speed, and feedstock flexibility; in addition, the use of a limited amount of binder makes the subsequent thermal debinding process easy. Nevertheless, the conventional approach to debind and sinter AMed components remains extremely slow, representing a bottleneck in the manufacturing process. In order to address such limitation, we explored different rapid sintering strategies: ultrafast high‐temperature sintering (UHS), pressureless spark plasma sintering (P‐SPS), and fast firing (FF), for the densification of BaTiO<jats:sub>3</jats:sub> components fabricated by DIW, one of the widely used lead‐free piezoceramics. All sintering technologies allow debinding and sintering of crack‐free components in a few minutes instead of several hours. The final density and microstructure are strongly dependent on the sintering atmosphere (inert for UHS and P‐SPS, air for FF) and a maximum relative density of only ≈72% was obtained when firing occurred in an inert environment, irrespective of the sintering technique (UHS and P‐SPS). An undesired phase transition from tetragonal to hexagonal BaTiO<jats:sub>3</jats:sub> was also observed upon UHS and ‐PSPS. On the contrary, FF in air yielded a density of about 95% in a few minutes while maintaining the desired tetragonal polymorph. The results provide proof of feasibility for rapid processing of BaTiO<jats:sub>3</jats:sub> components obtained by DIW.},
keywords = {Additive Manufacturing},
pubstate = {published},
tppubtype = {article}
}
Direct ink writing (DIW) is an attractive additive manufacturing (AM) technology because of its simplicity, production speed, and feedstock flexibility; in addition, the use of a limited amount of binder makes the subsequent thermal debinding process easy. Nevertheless, the conventional approach to debind and sinter AMed components remains extremely slow, representing a bottleneck in the manufacturing process. In order to address such limitation, we explored different rapid sintering strategies: ultrafast high‐temperature sintering (UHS), pressureless spark plasma sintering (P‐SPS), and fast firing (FF), for the densification of BaTiO<jats:sub>3</jats:sub> components fabricated by DIW, one of the widely used lead‐free piezoceramics. All sintering technologies allow debinding and sintering of crack‐free components in a few minutes instead of several hours. The final density and microstructure are strongly dependent on the sintering atmosphere (inert for UHS and P‐SPS, air for FF) and a maximum relative density of only ≈72% was obtained when firing occurred in an inert environment, irrespective of the sintering technique (UHS and P‐SPS). An undesired phase transition from tetragonal to hexagonal BaTiO<jats:sub>3</jats:sub> was also observed upon UHS and ‐PSPS. On the contrary, FF in air yielded a density of about 95% in a few minutes while maintaining the desired tetragonal polymorph. The results provide proof of feasibility for rapid processing of BaTiO<jats:sub>3</jats:sub> components obtained by DIW.
A. De Marzi; S. Diener; A. Campagnolo; G. Meneghetti; N. Katsikis; P. Colombo; G. Franchin
Ultra-lightweight silicon nitride truss-based structures fabricated via UV-assisted robot direct ink writing Journal Article
In: Materials & Design, pp. 113092, 2024, ISSN: 0264-1275.
Abstract | Links | BibTeX | Tags: Additive Manufacturing
@article{DEMARZI2024113092,
title = {Ultra-lightweight silicon nitride truss-based structures fabricated via UV-assisted robot direct ink writing},
author = {A. De Marzi and S. Diener and A. Campagnolo and G. Meneghetti and N. Katsikis and P. Colombo and G. Franchin},
url = {https://www.sciencedirect.com/science/article/pii/S0264127524004660},
doi = {https://doi.org/10.1016/j.matdes.2024.113092},
issn = {0264-1275},
year = {2024},
date = {2024-06-14},
urldate = {2024-06-14},
journal = {Materials & Design},
pages = {113092},
abstract = {Additive manufacturing techniques have gone beyond their reputation for rapid prototype production and are increasingly adopted for the manufacture of functional components comprising high-end materials and intricate lattice structures. Silicon nitride, renowned for its exceptional mechanical properties and thermal stability, has emerged as a promising candidate for lightweight structural applications. Nonetheless, its high refractive index and density have limited the fabrication of highly complex structures using extrusion and photopolymerization based techniques. In this work, a highly reactive silicon nitride-based ink with high solid loading is developed for the fabrication of ultra-lightweight, truss-based structures. By employing a robot UV-assisted direct ink writing process, it is possible to control the printing head orientation, thus overcoming the limited curing depth of silicon nitride-based inks. The failure behavior of the sintered lattice beam structures under 4-point bending loading has been modeled by applying a linear elastic fracture mechanics (LEFM) based approach to the results of finite element (FE) simulations.},
keywords = {Additive Manufacturing},
pubstate = {published},
tppubtype = {article}
}
Additive manufacturing techniques have gone beyond their reputation for rapid prototype production and are increasingly adopted for the manufacture of functional components comprising high-end materials and intricate lattice structures. Silicon nitride, renowned for its exceptional mechanical properties and thermal stability, has emerged as a promising candidate for lightweight structural applications. Nonetheless, its high refractive index and density have limited the fabrication of highly complex structures using extrusion and photopolymerization based techniques. In this work, a highly reactive silicon nitride-based ink with high solid loading is developed for the fabrication of ultra-lightweight, truss-based structures. By employing a robot UV-assisted direct ink writing process, it is possible to control the printing head orientation, thus overcoming the limited curing depth of silicon nitride-based inks. The failure behavior of the sintered lattice beam structures under 4-point bending loading has been modeled by applying a linear elastic fracture mechanics (LEFM) based approach to the results of finite element (FE) simulations.
K. Huang; G. Franchin; P. Colombo
Volumetric Additive Manufacturing of SiOC by Xolography Journal Article
In: Small, 2024, ISSN: 1613-6829.
Abstract | Links | BibTeX | Tags: Additive Manufacturing, Polymer-derived ceramics
@article{Huang2024,
title = {Volumetric Additive Manufacturing of SiOC by Xolography},
author = {K. Huang and G. Franchin and P. Colombo},
doi = {10.1002/smll.202402356},
issn = {1613-6829},
year = {2024},
date = {2024-05-10},
urldate = {2024-05-10},
journal = {Small},
publisher = {Wiley},
abstract = {Additive manufacturing (AM) of ceramics has significantly contributed to advancements in ceramic fabrication, solving some of the difficulties of conventional ceramic processing and providing additional possibilities for the structure and function of components. However, defects induced by the layer‐by‐layer approach on which traditional AM techniques are based still constitute a challenge to address. This study presents the volumetric AM of a SiOC ceramic from a preceramic polymer using xolography, a linear volumetric AM process that allows to avoid the staircase effect typical of other vat photopolymerization techniques. Besides optimizing the trade‐off between preceramic polymer content and transmittance, a pore generator is introduced to create transient channels for gas release before decomposition of the organic constituents and moieties, resulting in crack‐free solid ceramic structures even at low ceramic yield. Formulation optimization alleviated sinking of printed parts during printing and prevented shape distortion. Complex solid and porous ceramic structures with a smooth surface and sharp features are fabricated under the optimized parameters. This work provides a new method for the AM of ceramics at µm/mm scale with high surface quality and large geometry variety in an efficient way, opening the possibility for applications in fields such as micromechanical systems and microelectronic components.},
keywords = {Additive Manufacturing, Polymer-derived ceramics},
pubstate = {published},
tppubtype = {article}
}
Additive manufacturing (AM) of ceramics has significantly contributed to advancements in ceramic fabrication, solving some of the difficulties of conventional ceramic processing and providing additional possibilities for the structure and function of components. However, defects induced by the layer‐by‐layer approach on which traditional AM techniques are based still constitute a challenge to address. This study presents the volumetric AM of a SiOC ceramic from a preceramic polymer using xolography, a linear volumetric AM process that allows to avoid the staircase effect typical of other vat photopolymerization techniques. Besides optimizing the trade‐off between preceramic polymer content and transmittance, a pore generator is introduced to create transient channels for gas release before decomposition of the organic constituents and moieties, resulting in crack‐free solid ceramic structures even at low ceramic yield. Formulation optimization alleviated sinking of printed parts during printing and prevented shape distortion. Complex solid and porous ceramic structures with a smooth surface and sharp features are fabricated under the optimized parameters. This work provides a new method for the AM of ceramics at µm/mm scale with high surface quality and large geometry variety in an efficient way, opening the possibility for applications in fields such as micromechanical systems and microelectronic components.
E. Cepollaro; S. Cimino; M. D'Agostini; N. Gargiulo; G. Franchin; L. Lisi
3D-Printed Monoliths Based on Cu-Exchanged SSZ-13 as Catalyst for SCR of NOx Journal Article
In: Catalysts, vol. 14, iss. 1, no. 85, 2024.
Abstract | Links | BibTeX | Tags: Additive Manufacturing, Materials for the environment
@article{nokey,
title = {3D-Printed Monoliths Based on Cu-Exchanged SSZ-13 as Catalyst for SCR of NOx},
author = {E. Cepollaro and S. Cimino and M. D'Agostini and N. Gargiulo and G. Franchin and L. Lisi},
doi = {10.3390/catal14010085},
year = {2024},
date = {2024-01-19},
urldate = {2024-01-19},
journal = {Catalysts},
volume = {14},
number = {85},
issue = {1},
abstract = {Monoliths manufactured by Direct Ink Writing containing 60% SSZ-13 (SiO2/Al2O3 = 23) and SiO2 with 10% laponite as a binder were investigated as self-standing structured catalysts for NH3-SCR of NOx after a short (4 h) and prolonged (24 h) ion exchange with copper and then compared with pure SSZ-13 exchanged under the same conditions. The catalysts were characterized by morphological (XRD and SEM), textural (BET and pore size distribution), chemical (ICP-MS), red-ox (H2-TPR), and surface (NH3-TPD) analyses. The silica-based binder uniformly covered the SSZ-13 particles, and copper was uniformly distributed as well. The main features of the pure Cu-exchanged SSZ-13 zeolite were preserved in the composite monoliths with a negligible contribution of the binder fraction. NH3-SCR tests, carried out on both monolithic and powdered samples in the temperature range of 70–550 °C, showed that composite monoliths provided very good activity, and that the intrinsic activity of SSZ-13 was enhanced by the hierarchical structure of the composite material.},
keywords = {Additive Manufacturing, Materials for the environment},
pubstate = {published},
tppubtype = {article}
}
Monoliths manufactured by Direct Ink Writing containing 60% SSZ-13 (SiO2/Al2O3 = 23) and SiO2 with 10% laponite as a binder were investigated as self-standing structured catalysts for NH3-SCR of NOx after a short (4 h) and prolonged (24 h) ion exchange with copper and then compared with pure SSZ-13 exchanged under the same conditions. The catalysts were characterized by morphological (XRD and SEM), textural (BET and pore size distribution), chemical (ICP-MS), red-ox (H2-TPR), and surface (NH3-TPD) analyses. The silica-based binder uniformly covered the SSZ-13 particles, and copper was uniformly distributed as well. The main features of the pure Cu-exchanged SSZ-13 zeolite were preserved in the composite monoliths with a negligible contribution of the binder fraction. NH3-SCR tests, carried out on both monolithic and powdered samples in the temperature range of 70–550 °C, showed that composite monoliths provided very good activity, and that the intrinsic activity of SSZ-13 was enhanced by the hierarchical structure of the composite material.
A. W. Ourgessa; J. Kraxner; H. Elsayed; D. Galusek; E. Bernardo
Sustainable construction materials from alkali-activated waste fiberglass and waste refractory Journal Article
In: Open Ceramics, vol. 20, pp. 100678, 2024, ISSN: 2666-5395.
Abstract | Links | BibTeX | Tags: Materials for the environment
@article{OURGESSA2024100678,
title = {Sustainable construction materials from alkali-activated waste fiberglass and waste refractory},
author = {A. W. Ourgessa and J. Kraxner and H. Elsayed and D. Galusek and E. Bernardo},
url = {https://www.sciencedirect.com/science/article/pii/S2666539524001421},
doi = {https://doi.org/10.1016/j.oceram.2024.100678},
issn = {2666-5395},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-01},
journal = {Open Ceramics},
volume = {20},
pages = {100678},
abstract = {In this work, waste fiberglass was up-cycled, alone, or mixed with used alumina-zirconia-silica (AZS) refractory from dismantled glass melting furnaces. Alkali activation was performed by suspending fiberglass and fiberglass/AZS powders in NaOH aqueous solution of various concentrations (8M, 6M, and 3M). The activation of waste fiberglass with 8M NaOH yields a gel with calcium and sodium-containing aluminosilicate hydrates. The addition of AZS refractory enabled the release of aluminates into the solution, which had beneficial effects on the mechanical properties. Low molarity activation yielded weaker materials which could be used as precursors for firing at moderate temperatures (800 °C and 1000 °C) to create cellular glass-ceramics, with a total porosity of up to 92 %. The firing of 8M activated samples resulted in glass ceramics with a 66–75 % porosity range and compressive strength of 10–23Mpa. The compressive strength-to-density ratio before and after firing was comparable to that of established commercial construction materials.},
keywords = {Materials for the environment},
pubstate = {published},
tppubtype = {article}
}
In this work, waste fiberglass was up-cycled, alone, or mixed with used alumina-zirconia-silica (AZS) refractory from dismantled glass melting furnaces. Alkali activation was performed by suspending fiberglass and fiberglass/AZS powders in NaOH aqueous solution of various concentrations (8M, 6M, and 3M). The activation of waste fiberglass with 8M NaOH yields a gel with calcium and sodium-containing aluminosilicate hydrates. The addition of AZS refractory enabled the release of aluminates into the solution, which had beneficial effects on the mechanical properties. Low molarity activation yielded weaker materials which could be used as precursors for firing at moderate temperatures (800 °C and 1000 °C) to create cellular glass-ceramics, with a total porosity of up to 92 %. The firing of 8M activated samples resulted in glass ceramics with a 66–75 % porosity range and compressive strength of 10–23Mpa. The compressive strength-to-density ratio before and after firing was comparable to that of established commercial construction materials.
S. Bhandari; P. Veteška; G. Vajpayee; M. Hinterstein; Ľ. Bača; Z. Hajdúchová; Z. Špitalský; G. Franchin; M. Janek
Material-extrusion based additive manufacturing of BaTiO3 ceramics: from filament production to sintered properties Journal Article
In: Additive Manufacturing, pp. 104238, 2024, ISSN: 2214-8604.
Abstract | Links | BibTeX | Tags: Additive Manufacturing
@article{BHANDARI2024104238,
title = {Material-extrusion based additive manufacturing of BaTiO3 ceramics: from filament production to sintered properties},
author = {S. Bhandari and P. Veteška and G. Vajpayee and M. Hinterstein and Ľ. Bača and Z. Hajdúchová and Z. Špitalský and G. Franchin and M. Janek},
url = {https://www.sciencedirect.com/science/article/pii/S2214860424002847},
doi = {https://doi.org/10.1016/j.addma.2024.104238},
issn = {2214-8604},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-01},
journal = {Additive Manufacturing},
pages = {104238},
abstract = {Material extrusion (MEX) of thermoplastic filaments represents one of the most widely adopted additive manufacturing (AM) technologies. Unlike vat photopolymerization and powder-bed fusion methods that require high energy sources such as UV light and lasers, this fabrication method can be adapted for the fabrication of ceramics by using ceramic loaded filaments as feedstock, yet still employing relatively cheap equipment meant for polymeric materials with little adaptation of the process parameters; this potentially enables a broader diffusion of AM ceramic components. In this work, composite filaments with various weight fractions (60 – 80wt.%) of BaTiO3 were fabricated and characterized by electron microscopy, compressive mechanical testing, rheometry and thermogravimetric analysis to ensure a smooth and reliable printing process. After optimizing the printing parameters, the dense and porous printed samples were carefully debinded and sintered to obtain dense (~ 92%) and defect-free ceramic bodies. The sintered samples were characterized for phase development, microstructure, and pore size distribution. Careful observations reveal a particular range of pore size (0.1 – 5µm), which originates from the binder burn out process. The dielectric and ferroelectric properties of the fabricated samples were in good agreement with those reported in previous literature. This work provides a foundation for rapid prototyping of functional electro ceramics into reliable products with desired functional properties.},
keywords = {Additive Manufacturing},
pubstate = {published},
tppubtype = {article}
}
Material extrusion (MEX) of thermoplastic filaments represents one of the most widely adopted additive manufacturing (AM) technologies. Unlike vat photopolymerization and powder-bed fusion methods that require high energy sources such as UV light and lasers, this fabrication method can be adapted for the fabrication of ceramics by using ceramic loaded filaments as feedstock, yet still employing relatively cheap equipment meant for polymeric materials with little adaptation of the process parameters; this potentially enables a broader diffusion of AM ceramic components. In this work, composite filaments with various weight fractions (60 – 80wt.%) of BaTiO3 were fabricated and characterized by electron microscopy, compressive mechanical testing, rheometry and thermogravimetric analysis to ensure a smooth and reliable printing process. After optimizing the printing parameters, the dense and porous printed samples were carefully debinded and sintered to obtain dense (~ 92%) and defect-free ceramic bodies. The sintered samples were characterized for phase development, microstructure, and pore size distribution. Careful observations reveal a particular range of pore size (0.1 – 5µm), which originates from the binder burn out process. The dielectric and ferroelectric properties of the fabricated samples were in good agreement with those reported in previous literature. This work provides a foundation for rapid prototyping of functional electro ceramics into reliable products with desired functional properties.
K. Huang; A. De Marzi; G. Franchin; P. Colombo
UV-assisted Robotic Arm Freeforming of SiOC Ceramics from a Preceramic Polymer Journal Article
In: Additive Manufacturing, pp. 104051, 2024, ISSN: 2214-8604.
Abstract | Links | BibTeX | Tags: Additive Manufacturing, Polymer-derived ceramics
@article{HUANG2024104051,
title = {UV-assisted Robotic Arm Freeforming of SiOC Ceramics from a Preceramic Polymer},
author = {K. Huang and A. De Marzi and G. Franchin and P. Colombo},
url = {https://www.sciencedirect.com/science/article/pii/S2214860424000976},
doi = {https://doi.org/10.1016/j.addma.2024.104051},
issn = {2214-8604},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-01},
journal = {Additive Manufacturing},
pages = {104051},
abstract = {Material extrusion is a very common and facile additive manufacturing technique for ceramic materials, allowing for rapid design and fabrication of 3D structures without expensive tools. However, fabricating sophisticated structures with large spanning parts and overhanging features using this technology is still a challenge. Here, UV-assisted additive manufacturing is enabled by performing material extrusion with the assistance of UV light using mixture of a preceramic polymer and a photopolymer. The rheological properties of the ink were investigated under UV light radiation to optimize the printing parameters to achieve excellent printability. Complex ceramic structures were fabricated with this method, such as spiral and truss structures, which would be very difficult to obtain using traditional material extrusion without sacrificial supports. These structures have potential application in lightweight ceramic components, such as sandwich structures.},
keywords = {Additive Manufacturing, Polymer-derived ceramics},
pubstate = {published},
tppubtype = {article}
}
Material extrusion is a very common and facile additive manufacturing technique for ceramic materials, allowing for rapid design and fabrication of 3D structures without expensive tools. However, fabricating sophisticated structures with large spanning parts and overhanging features using this technology is still a challenge. Here, UV-assisted additive manufacturing is enabled by performing material extrusion with the assistance of UV light using mixture of a preceramic polymer and a photopolymer. The rheological properties of the ink were investigated under UV light radiation to optimize the printing parameters to achieve excellent printability. Complex ceramic structures were fabricated with this method, such as spiral and truss structures, which would be very difficult to obtain using traditional material extrusion without sacrificial supports. These structures have potential application in lightweight ceramic components, such as sandwich structures.
M. Magarotto; L. Schenato; G. Franchin; M. Santagiustina; A. Galtarossa; A.-D. Capobianco
Cylindrical Waveguides for Microwave Spoof Surface Plasmon Polaritons Journal Article
In: IEEE Access, pp. 1-1, 2024.
@article{10423622,
title = {Cylindrical Waveguides for Microwave Spoof Surface Plasmon Polaritons},
author = {M. Magarotto and L. Schenato and G. Franchin and M. Santagiustina and A. Galtarossa and A.-D. Capobianco},
doi = {10.1109/ACCESS.2024.3363412},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-01},
journal = {IEEE Access},
pages = {1-1},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2023
L. Biasetto; A. Gleadall; V. Gastaldi
Ink Tuning for Direct Ink Writing of Planar Metallic Lattices Journal Article
In: Adv Eng Mater, vol. 25, no. 20, 2023, ISSN: 1527-2648.
Abstract | Links | BibTeX | Tags: Additive Manufacturing
@article{Biasetto2023,
title = {Ink Tuning for Direct Ink Writing of Planar Metallic Lattices},
author = {L. Biasetto and A. Gleadall and V. Gastaldi},
doi = {10.1002/adem.202201858},
issn = {1527-2648},
year = {2023},
date = {2023-10-00},
urldate = {2023-10-00},
journal = {Adv Eng Mater},
volume = {25},
number = {20},
publisher = {Wiley},
abstract = {316L and Cu‐based inks are developed to 3D‐printed tetrachiral auxetic structures. The main objectives of the work are to study the effects of powders composition and powder:binder volume ratio on rheological properties and printability of the inks. Following these results, customized Gcode is developed using FullControl Gcode Designer open‐source software to 3D print intricate tetrachiral auxetic structures. The results reported in this work show how powder composition (316L versus Cu) has less effect on the inks’ rheological behavior than powder size distribution and powders:binder volume ratio. In terms of rheological parameters, the zero‐shear rate viscosity mainly affects the capability of the printed ink to retain its shape after printing, while the yield stress affects the printability. The printed and sintered auxetic structures achieve the intended lattice‐geometry design.},
keywords = {Additive Manufacturing},
pubstate = {published},
tppubtype = {article}
}
316L and Cu‐based inks are developed to 3D‐printed tetrachiral auxetic structures. The main objectives of the work are to study the effects of powders composition and powder:binder volume ratio on rheological properties and printability of the inks. Following these results, customized Gcode is developed using FullControl Gcode Designer open‐source software to 3D print intricate tetrachiral auxetic structures. The results reported in this work show how powder composition (316L versus Cu) has less effect on the inks’ rheological behavior than powder size distribution and powders:binder volume ratio. In terms of rheological parameters, the zero‐shear rate viscosity mainly affects the capability of the printed ink to retain its shape after printing, while the yield stress affects the printability. The printed and sintered auxetic structures achieve the intended lattice‐geometry design.
S. Bhandari; C. Maniere; F. Sedona; E. De Bona; V. M. Sglavo; P. Colombo; L. Fambri; M. Biesuz; G. Franchin
Ultra-rapid debinding and sintering of additively manufactured ceramics by ultrafast high-temperature sintering Journal Article
In: Journal of the European Ceramic Society, 2023, ISSN: 0955-2219.
Abstract | Links | BibTeX | Tags: Additive Manufacturing
@article{BHANDARI2023,
title = {Ultra-rapid debinding and sintering of additively manufactured ceramics by ultrafast high-temperature sintering},
author = {S. Bhandari and C. Maniere and F. Sedona and E. De Bona and V. M. Sglavo and P. Colombo and L. Fambri and M. Biesuz and G. Franchin},
url = {https://www.sciencedirect.com/science/article/pii/S0955221923006660},
doi = {https://doi.org/10.1016/j.jeurceramsoc.2023.08.040},
issn = {0955-2219},
year = {2023},
date = {2023-08-25},
urldate = {2023-01-01},
journal = {Journal of the European Ceramic Society},
abstract = {In recent years, additive manufacturing (AM) of ceramics has significantly advanced in terms of the range of equipment available, printing resolution and productivity. Most techniques involve the use of ceramic powders embedded in an organic binder which is typically removed through a slow thermal debinding process. Herein, we prove for the first time that ultra-rapid debinding and sintering are possible for complex 3YSZ components produced using material extrusion technology. The printed components were first chemically debinded in acetone thus removing about one-half of the binder, and then thermally debinded and sintered by ultrafast high-temperature sintering (UHS) in a single-step process (30 to 120s). Fully dense components were obtained with tailored microstructure and nanometric grain size. The sintered artefacts were crack-free even at the microscopic level. This approach paves the way for rapid processing (debinding and sintering) of additively manufactured ceramics with reduced energy consumption and carbon footprint.},
keywords = {Additive Manufacturing},
pubstate = {published},
tppubtype = {article}
}
In recent years, additive manufacturing (AM) of ceramics has significantly advanced in terms of the range of equipment available, printing resolution and productivity. Most techniques involve the use of ceramic powders embedded in an organic binder which is typically removed through a slow thermal debinding process. Herein, we prove for the first time that ultra-rapid debinding and sintering are possible for complex 3YSZ components produced using material extrusion technology. The printed components were first chemically debinded in acetone thus removing about one-half of the binder, and then thermally debinded and sintered by ultrafast high-temperature sintering (UHS) in a single-step process (30 to 120s). Fully dense components were obtained with tailored microstructure and nanometric grain size. The sintered artefacts were crack-free even at the microscopic level. This approach paves the way for rapid processing (debinding and sintering) of additively manufactured ceramics with reduced energy consumption and carbon footprint.
N. Shezad; M. D'Agostini; A. Ezzine; G. Franchin; P. Colombo; F. Akhtar
3D-printed zeolite 13X-Strontium chloride units as ammonia carriers Journal Article
In: Heliyon, pp. e19376, 2023, ISSN: 2405-8440.
Abstract | Links | BibTeX | Tags: Additive Manufacturing, Materials for the environment
@article{SHEZAD2023e19376,
title = {3D-printed zeolite 13X-Strontium chloride units as ammonia carriers},
author = {N. Shezad and M. D'Agostini and A. Ezzine and G. Franchin and P. Colombo and F. Akhtar},
url = {https://www.sciencedirect.com/science/article/pii/S2405844023065842},
doi = {https://doi.org/10.1016/j.heliyon.2023.e19376},
issn = {2405-8440},
year = {2023},
date = {2023-08-22},
urldate = {2023-08-22},
journal = {Heliyon},
pages = {e19376},
abstract = {The selective catalytic reduction (SCR) system in automobile using urea solution as a source of NH3 suffer from solid deposit problem in pipe lines and poor efficiency during engine startup. Although direct use of high pressure NH3 is restricted due to safety concern, which can be overcome by using solid sorbents as NH3 carrier. Strontium chloride (SrCl2) is considered the best sorbent due to its high sorption capacity; however, challenges are associated with the processing of stable engineering structures due to extraordinary volume expansion during the NH3 sorption. This study reports the fabrication of a novel structure consisting of a zeolite cage enclosing the SrCl2 pellet (SPZC) through extrusion-based 3D printing (Direct Ink Writing). The printed SPZC structure demonstrated steady sorption of NH3 for 10 consecutive cycles without significant uptake capacity and structural integrity loss. Furthermore, the structure exhibited improved sorption and desorption kinetics than pure SrCl2. The synergistic effect of zeolite as physisorbent and SrCl2 as chemisorbent in the novel composite structure enabled the low-pressure (<0.4 bar) and high-pressure (>0.4 bar) NH3 sorption, compared to pure SrCl2, which absorbed NH3 at pressures above 0.4 bar. Regeneration of SPZC composite sorbent under evacuation showed that 87.5% percent of NH3 was desorbed at 20 °C. Thus, the results demonstrate that the rationally designed novel SPZC structure offers safe and efficient storage of NH3 in the SCR system and other applications.},
keywords = {Additive Manufacturing, Materials for the environment},
pubstate = {published},
tppubtype = {article}
}
The selective catalytic reduction (SCR) system in automobile using urea solution as a source of NH3 suffer from solid deposit problem in pipe lines and poor efficiency during engine startup. Although direct use of high pressure NH3 is restricted due to safety concern, which can be overcome by using solid sorbents as NH3 carrier. Strontium chloride (SrCl2) is considered the best sorbent due to its high sorption capacity; however, challenges are associated with the processing of stable engineering structures due to extraordinary volume expansion during the NH3 sorption. This study reports the fabrication of a novel structure consisting of a zeolite cage enclosing the SrCl2 pellet (SPZC) through extrusion-based 3D printing (Direct Ink Writing). The printed SPZC structure demonstrated steady sorption of NH3 for 10 consecutive cycles without significant uptake capacity and structural integrity loss. Furthermore, the structure exhibited improved sorption and desorption kinetics than pure SrCl2. The synergistic effect of zeolite as physisorbent and SrCl2 as chemisorbent in the novel composite structure enabled the low-pressure (<0.4 bar) and high-pressure (>0.4 bar) NH3 sorption, compared to pure SrCl2, which absorbed NH3 at pressures above 0.4 bar. Regeneration of SPZC composite sorbent under evacuation showed that 87.5% percent of NH3 was desorbed at 20 °C. Thus, the results demonstrate that the rationally designed novel SPZC structure offers safe and efficient storage of NH3 in the SCR system and other applications.
P. Colombo; G. Franchin
Improving glass nanostructure fabrication Journal Article
In: Science, vol. 380, no. 6648, pp. 895–896, 2023, ISSN: 1095-9203.
Abstract | Links | BibTeX | Tags: Additive Manufacturing, Polymer-derived ceramics
@article{pmid37262160,
title = {Improving glass nanostructure fabrication},
author = {P. Colombo and G. Franchin},
url = {https://www.science.org/stoken/author-tokens/ST-1233/full},
doi = {10.1126/science.adi2747},
issn = {1095-9203},
year = {2023},
date = {2023-06-01},
urldate = {2023-06-01},
journal = {Science},
volume = {380},
number = {6648},
pages = {895--896},
abstract = {A new method offers high-resolution three-dimensional printing and low-temperature firing.},
keywords = {Additive Manufacturing, Polymer-derived ceramics},
pubstate = {published},
tppubtype = {article}
}
A new method offers high-resolution three-dimensional printing and low-temperature firing.
C. Bagci; G. Tameni; H. Elsayed; E. Bernardo
Sustainable manufacturing of new construction material from alkali activation of volcanic tuff Journal Article
In: Materials Today Communications, vol. 36, pp. 106645, 2023, ISSN: 2352-4928.
Abstract | Links | BibTeX | Tags: Materials for the environment
@article{BAGCI2023106645,
title = {Sustainable manufacturing of new construction material from alkali activation of volcanic tuff},
author = {C. Bagci and G. Tameni and H. Elsayed and E. Bernardo},
url = {https://www.sciencedirect.com/science/article/pii/S2352492823013363},
doi = {https://doi.org/10.1016/j.mtcomm.2023.106645},
issn = {2352-4928},
year = {2023},
date = {2023-01-01},
urldate = {2023-01-01},
journal = {Materials Today Communications},
volume = {36},
pages = {106645},
abstract = {The current climate emergency leads to reduction of virgin raw material extraction and promotes circular economy. In this framework, alkali activation of unemployed fraction of grey tuff, combined with glass waste, provides a range of sustainable construction materials. For the sake of sustainability, tuff powder was subjected to rapid attack (30 min), operated by a ‘weak’ alkaline solution (3 M NaOH), and then left to dry at low temperature (75 °C) for 72 h. The addition of Triton X-100 surfactant was considered to obtain foams starting from slurries with different liquid-to-solid ratio. A thermal treatment was applied to selected samples, at low temperature (700 °C). Despite the ‘mild’ activation conditions, all products survived after immersion in boiling water or acid solution, already in the unfired state, according to the formation of a multiphasic gel. The strength-to-density ratio, especially for foams, in both unfired and fired form, compares well with that of already existing construction materials (e.g. it could exceed 5 MPa cm3/g).},
keywords = {Materials for the environment},
pubstate = {published},
tppubtype = {article}
}
The current climate emergency leads to reduction of virgin raw material extraction and promotes circular economy. In this framework, alkali activation of unemployed fraction of grey tuff, combined with glass waste, provides a range of sustainable construction materials. For the sake of sustainability, tuff powder was subjected to rapid attack (30 min), operated by a ‘weak’ alkaline solution (3 M NaOH), and then left to dry at low temperature (75 °C) for 72 h. The addition of Triton X-100 surfactant was considered to obtain foams starting from slurries with different liquid-to-solid ratio. A thermal treatment was applied to selected samples, at low temperature (700 °C). Despite the ‘mild’ activation conditions, all products survived after immersion in boiling water or acid solution, already in the unfired state, according to the formation of a multiphasic gel. The strength-to-density ratio, especially for foams, in both unfired and fired form, compares well with that of already existing construction materials (e.g. it could exceed 5 MPa cm3/g).
A. Breda; A. Zanini; A. Campagnolo; S. Corradetti; M. Manzolaro; G. Meneghetti; P. Colombo; M. Ballan; G. Franchin
Production and mechanical characterization of Titanium Carbide ISOL target disks fabricated by direct ink writing Journal Article
In: Ceramics International, 2023, ISSN: 0272-8842.
Abstract | Links | BibTeX | Tags: Additive Manufacturing
@article{BREDA2023,
title = {Production and mechanical characterization of Titanium Carbide ISOL target disks fabricated by direct ink writing},
author = {A. Breda and A. Zanini and A. Campagnolo and S. Corradetti and M. Manzolaro and G. Meneghetti and P. Colombo and M. Ballan and G. Franchin},
url = {https://www.sciencedirect.com/science/article/pii/S0272884223020485},
doi = {https://doi.org/10.1016/j.ceramint.2023.07.121},
issn = {0272-8842},
year = {2023},
date = {2023-01-01},
urldate = {2023-01-01},
journal = {Ceramics International},
abstract = {Titanium carbide boasts a large variety of high-temperature applications from aerospace to electronics and is also employed as Isotope Separation On-Line target for the production of Radioactive Ion Beams, which are employed in numerous research and technological fields, ranging from nuclear physics to medical applications. High working temperature, open and tailored porosity and resistance to thermal stresses are fundamental characteristics for this kind of targets. In this work, an extrusion-based additive manufacturing technique (Direct Ink Writing) was used for the fabrication of complex three-dimensional macro-porous structures in the shape of disks with dimensions compatible for their use as targets. An ink containing a suspension of TiC powders with solid loading of 47.5 vol% was prepared and its rheological properties were investigated. Afterwards, single filaments with an average diameter of 0.36 mm were produced and characterized with four-point bending tests to determine the bulk material tensile strength and Young's modulus. TiC targets were then manufactured and their mechanical properties were characterized with the Ball on Three Balls approach, a biaxial flexural test suitable for disk-shaped samples. For both flexural tests, a Finite Element model was developed representatively reproducing the experimental results. The calculated tensile strength values for both filaments and disks were analyzed with Weibull's statistical approach to provide reference stress limit, corresponding to a survival probability of 99.9%.},
keywords = {Additive Manufacturing},
pubstate = {published},
tppubtype = {article}
}
Titanium carbide boasts a large variety of high-temperature applications from aerospace to electronics and is also employed as Isotope Separation On-Line target for the production of Radioactive Ion Beams, which are employed in numerous research and technological fields, ranging from nuclear physics to medical applications. High working temperature, open and tailored porosity and resistance to thermal stresses are fundamental characteristics for this kind of targets. In this work, an extrusion-based additive manufacturing technique (Direct Ink Writing) was used for the fabrication of complex three-dimensional macro-porous structures in the shape of disks with dimensions compatible for their use as targets. An ink containing a suspension of TiC powders with solid loading of 47.5 vol% was prepared and its rheological properties were investigated. Afterwards, single filaments with an average diameter of 0.36 mm were produced and characterized with four-point bending tests to determine the bulk material tensile strength and Young's modulus. TiC targets were then manufactured and their mechanical properties were characterized with the Ball on Three Balls approach, a biaxial flexural test suitable for disk-shaped samples. For both flexural tests, a Finite Element model was developed representatively reproducing the experimental results. The calculated tensile strength values for both filaments and disks were analyzed with Weibull's statistical approach to provide reference stress limit, corresponding to a survival probability of 99.9%.
M. Muracchioli; G. Menardi; M. D'Agostini; G. Franchin; P. Colombo
Modeling the compressive strength of metakaolin-based geopolymers based on the statistical analysis of experimental data Journal Article
In: Applied Clay Science, vol. 242, pp. 107020, 2023, ISSN: 0169-1317.
Abstract | Links | BibTeX | Tags: Materials for the environment
@article{MURACCHIOLI2023107020,
title = {Modeling the compressive strength of metakaolin-based geopolymers based on the statistical analysis of experimental data},
author = {M. Muracchioli and G. Menardi and M. D'Agostini and G. Franchin and P. Colombo},
url = {https://authors.elsevier.com/c/1hHC3cTCCHH3T},
doi = {https://doi.org/10.1016/j.clay.2023.107020},
issn = {0169-1317},
year = {2023},
date = {2023-01-01},
urldate = {2023-01-01},
journal = {Applied Clay Science},
volume = {242},
pages = {107020},
abstract = {The relationship between the compressive strength of metakaolin-based geopolymer samples and different processing conditions has been investigated for both potassium and sodium based geopolymer systems. Cubic geopolymer samples were prepared by mixing the slurry for 1 h in a thermostatic bath at 0 °C. >1200 samples have been tested to gather enough data to carry out a meaningful statistical analysis. All the data evaluation and model development have been carried out extensively using R. The variation of curing and aging time, curing temperature, SiO2/Al2O3 and H2O/Al2O3 molar ratios has been accounted for via the application of statistical models whose reliability has been suitably checked. Curing has been performed in a sealed container at 100% relative humidity. Aging has been conducted in a climate chamber kept at 75% of relative humidity using an oversaturated solution of NaCl. Curing time has proved a positive relationship with compressive strength while aging time does not show evidence of any significant effect. Curing temperature negatively affects compressive strength. Increasing the SiO2/Al2O3 molar ratio results in an increase of the compressive strength within a certain range of values for the ratio; however, above a threshold (3.8 for the potassium-based and 3.4 for the sodium-based geopolymer system) the mechanical properties decrease. The H2O/Al2O3 molar ratio displayed an inverse proportionality with the compressive strength except for the sodium-based geopolymer, where the mechanical properties initially increased. A further comprehensive and statistically sound model has been proposed that allows us to predict the strength of geopolymer samples as a function of process variables and their composition, ranging in a rather wide set of values.},
keywords = {Materials for the environment},
pubstate = {published},
tppubtype = {article}
}
The relationship between the compressive strength of metakaolin-based geopolymer samples and different processing conditions has been investigated for both potassium and sodium based geopolymer systems. Cubic geopolymer samples were prepared by mixing the slurry for 1 h in a thermostatic bath at 0 °C. >1200 samples have been tested to gather enough data to carry out a meaningful statistical analysis. All the data evaluation and model development have been carried out extensively using R. The variation of curing and aging time, curing temperature, SiO2/Al2O3 and H2O/Al2O3 molar ratios has been accounted for via the application of statistical models whose reliability has been suitably checked. Curing has been performed in a sealed container at 100% relative humidity. Aging has been conducted in a climate chamber kept at 75% of relative humidity using an oversaturated solution of NaCl. Curing time has proved a positive relationship with compressive strength while aging time does not show evidence of any significant effect. Curing temperature negatively affects compressive strength. Increasing the SiO2/Al2O3 molar ratio results in an increase of the compressive strength within a certain range of values for the ratio; however, above a threshold (3.8 for the potassium-based and 3.4 for the sodium-based geopolymer system) the mechanical properties decrease. The H2O/Al2O3 molar ratio displayed an inverse proportionality with the compressive strength except for the sodium-based geopolymer, where the mechanical properties initially increased. A further comprehensive and statistically sound model has been proposed that allows us to predict the strength of geopolymer samples as a function of process variables and their composition, ranging in a rather wide set of values.
Y. Feng; X. Guo; H. Elsayed; K. Huang; G. Franchin; G. Motz; Y. Tong; H. Gong; P. Colombo
In: Ceramics International, 2023, ISSN: 0272-8842.
Abstract | Links | BibTeX | Tags: Additive Manufacturing, Polymer-derived ceramics
@article{FENG2023,
title = {Enhanced electromagnetic microwave absorption properties of SiCN(Fe) ceramics produced by additive manufacturing via in-situ reaction of ferrocene},
author = {Y. Feng and X. Guo and H. Elsayed and K. Huang and G. Franchin and G. Motz and Y. Tong and H. Gong and P. Colombo},
url = {https://www.sciencedirect.com/science/article/pii/S0272884223012828},
doi = {https://doi.org/10.1016/j.ceramint.2023.05.035},
issn = {0272-8842},
year = {2023},
date = {2023-01-01},
urldate = {2023-01-01},
journal = {Ceramics International},
abstract = {SiCN(Fe) ceramics with excellent electromagnetic wave (EMW) absorption performance were successfully prepared from a preceramic polymer doped with ferrocene. Additive manufacturing (Digital Light Processing), providing enhanced structural design ability, was employed to fabricate samples with complex architectures. During pyrolysis, ferrocene catalyzed the in-situ formation of a large amount of turbostratic carbon, graphite and SiC nanosized phases, which formed carrier channels in the electromagnetic field and increased the conductivity loss. Meanwhile, it also increased the dipole polarization, interface polarization and the dielectric properties of the material, which finally enhanced the EMW absorption capacity of SiCN(Fe) ceramics. When containing 0.5 wt% ferrocene, the material showed good performance with EAB 4.57 GHz at 1.30 mm, and RLmin −61.34 dB at 2.22 mm. The RLmin of 3D-SiCN-0.5 ceramics was −6 dB, and the RL of the X-band was lower than −4 dB at 2 mm.},
keywords = {Additive Manufacturing, Polymer-derived ceramics},
pubstate = {published},
tppubtype = {article}
}
SiCN(Fe) ceramics with excellent electromagnetic wave (EMW) absorption performance were successfully prepared from a preceramic polymer doped with ferrocene. Additive manufacturing (Digital Light Processing), providing enhanced structural design ability, was employed to fabricate samples with complex architectures. During pyrolysis, ferrocene catalyzed the in-situ formation of a large amount of turbostratic carbon, graphite and SiC nanosized phases, which formed carrier channels in the electromagnetic field and increased the conductivity loss. Meanwhile, it also increased the dipole polarization, interface polarization and the dielectric properties of the material, which finally enhanced the EMW absorption capacity of SiCN(Fe) ceramics. When containing 0.5 wt% ferrocene, the material showed good performance with EAB 4.57 GHz at 1.30 mm, and RLmin −61.34 dB at 2.22 mm. The RLmin of 3D-SiCN-0.5 ceramics was −6 dB, and the RL of the X-band was lower than −4 dB at 2 mm.