Polymer-derived Si3N4 nanofelts for flexible, high temperature, lightweight and easy-manufacturable super-thermal insulators

Biesuz, Mattia; Zera, Emanuele; Tomasi, Michele; Jana, Prasanta; Ersen, Ovidiu; Baaziz, Walid; Lindemann, André; Sorarù, Gian Domenico

doi:10.1016/j.apmt.2020.100648

Cited by 22 publications

(36 citation statements)

References 34 publications

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“…The samples were kept in the flash state for 120 s and then the power source was switched off. In order to understand the effect of a thermal insulation systems on the densification by FS, a 5 mm thick silicon nitride felt (produced according to [ 46 ]) was wrapped around some samples (50 vol.% of YSZ) before the test. All flash experiments were carried out in air.…”

Section: Methodsmentioning

confidence: 99%

Flash Sintering of YSZ/Al2O3 Composites: Effect of Processing and Testing Conditions

Biesuz

Ometto

2021

Materials

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The flash sintering behavior of yttria-stabilized zirconia/alumina composites was investigated to understand the role of the fundamental processing and testing parameters (electric field intensity, electric current limit, thermal insulation, homogeneity and dispersion of the two phases) on densification. A strong relation between the composite compositions and the electric parameters needed to promote flash sintering is revealed. Interestingly, the composite preparation method, which affects the two-phases dispersion homogeneity, was shown to have a relevant effect on the flash onset conditions, where the more homogeneous material is more difficult to be flashed. Moreover, the use of a simple thermal insulation system around the green body allowed to improve the final density of the composites under constant electric current.

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Section: Methodsmentioning

confidence: 99%

Flash Sintering of YSZ/Al2O3 Composites: Effect of Processing and Testing Conditions

Biesuz

Ometto

2021

Materials

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“…The felt microstructure is constituted by silicon nitride nanobelts, whose size primarily depend on the PU foam PPI: large cell-foams leading to thinner and longer Si 3 N 4 fibres (Fig. 1c, d) [57]. The nanobelts are constituted by dense single crystals as shown by the TEM investigations reported in our previous work [57].…”

Section: Resultsmentioning

confidence: 79%

“…In a recent patent [55], we have disclosed a novel polymer-derived-ceramic (PDC) synthesis route for the preparation of a-Si 3 N 4 nanofibrous structures (nanofelts). The process is pretty simple and allows the production of nanofelts with various geometries of possible industrial interest [56,57]: an open-cells polyurethane foam is impregnated with a polysiloxane and pyrolized in N 2 . At low temperature (\ 1000°C) the pre-ceramic resin is converted into an amorphous SiOC network embedding nano-graphitic carbon clusters [58,59]; this structure replicates the parent PU foam geometry.…”

Section: Introductionmentioning

confidence: 99%

Si3N4 nanofelts/paraffin composites as novel thermal energy storage architecture

et al. 2020

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The environmental problems associated with global warming are urging the development of novel systems to manage and reduce the energy consumption. An attractive route to improve the energy efficiency of civil buildings is to store the thermal energy thanks, during heating, to the phase transition of a phase-change material (as paraffin) from the solid to the liquid state and vice versa. The stored energy can be then released under cooling. Herein, we developed a novel material (nanofelt) constituted by Si3N4 nanobelts able to absorb huge amounts of liquid paraffin in the molten state and to act as an efficient shape stabilizer. The nanofelt manufacturing technology is very simple and easy to be scaled-up. The effect of the Si3N4 nanofelts density and microstructure on the paraffin sorption and leakage and on the thermal properties of the resulting composite structures is investigated. It is shown that the produced Si3N4/paraffin composites are able to retain enormous fractions of paraffin (up to 70 wt%) after 44 day of desorption test on absorbent paper towel. The thermal energy storage efficiency measured through calorimetric tests is as high as 77.4% in heating and 80.1% in cooling.

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“…[3][4][5][6][7][8][9] The vast range of processing techniques which can be applied to this family of ceramics has led to the fabrication of a multitude of shapes such as fibers, thin films, porous components (foams wiopen/closed cell, aerogels), 3D printed lattices and objects, microelectromechanical systems (MEMS), etc. [10][11][12][13][14][15][16][17][18][19] Among the most striking features of this process is the possibility to fabricate, at a relatively low temperature (1000°C-1400°C), silicon oxycarbides (SiOC), and silicon carbonitrides (SiCN) ceramics which display elastic modulus, hardness, and creep resistance similar or even better than the corresponding materials sintered (such as Si 3 N 4 or SiC) or melted (vitreous silica) at much higher temperature. 20,21 Accordingly, silicon oxycarbide glasses pyrolyzed at 1000°C display elastic modulus, hardness, and viscosity which are well above those reported in the literature for silica glass, and amorphous silicon carbonitride has shown the highest viscosity reported for an amorphous ceramic so far.…”

Section: Introductionmentioning

confidence: 99%

“…These materials, known as polymer‐derived ceramics (PDCs), have shown unique mechanical and functional properties and have been proposed for different application in many fields 3‐9 . The vast range of processing techniques which can be applied to this family of ceramics has led to the fabrication of a multitude of shapes such as fibers, thin films, porous components (foams wiopen/closed cell, aerogels), 3D printed lattices and objects, microelectromechanical systems (MEMS), etc 10‐19 …”

Section: Introductionmentioning

confidence: 99%

Effect of the pyrolysis atmosphere on the mechanical properties of polymer‐derived SiOC and SiCN

et al. 2020

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Mechanical properties of polymer‐derived ceramics are usually measured on samples pyrolyzed in inert atmosphere. Here, we report the hardness and elastic modulus of SiOC and SiCN pyrolyzed in both inert (Ar) and reactive (CO2) atmosphere. The external surface of the specimens exposed to the pyrolysis gas was characterized by Vickers microhardness measurements and infrared spectroscopy. The elastic modulus was evaluated by three‐point bending tests on thin (150‐200 µm) and dense specimens. Polished sections of the SiOC samples were prepared to study, by energy‐dispersive X‐ray spectroscopy (EDXS) and nanoindentation, how the elemental composition, hardness, and elastic modulus vary from the surface toward the bulk. For both compositions, pyrolysis in CO2 leads to a strong decrease in the hardness and elastic modulus. The hardness of both the samples pyrolyzed in CO2 approaches the typical value for fused silica, suggesting that CO2 selectively breaks the Si–C and Si–N bonds and leads to the formation of a silica‐like network. EDXS and nanoindentation reveal that the modification induced by the CO2 flow extends below the surface at least for a thickness of about 30 µm.

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Polymer-derived Si3N4 nanofelts for flexible, high temperature, lightweight and easy-manufacturable super-thermal insulators

Cited by 22 publications

References 34 publications

Flash Sintering of YSZ/Al2O3 Composites: Effect of Processing and Testing Conditions

Flash Sintering of YSZ/Al2O3 Composites: Effect of Processing and Testing Conditions

Si3N4 nanofelts/paraffin composites as novel thermal energy storage architecture

Effect of the pyrolysis atmosphere on the mechanical properties of polymer‐derived SiOC and SiCN

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