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Abstract The Cold Sintering Process (CSP) can provide opportunities to fabricate high-performance BaTiO3dielectric composites with polymer materials that are typically difficult to impossible to co-process under a conventional sintering process. Therefore, we investigated the preparation process of BaTiO3sintered body by CSP and integrated a well-dispersed intergranular polymer phase. In this study, we focused on preparing BaTiO3and Polytetrafluoroethylene (PTFE) composites. We considered the importance of the particle size of the PTFE phase, and correlated the impact on the composite dielectric properties. Through fitting a general-mixing-law to the dielectric properties as a function of volume fraction, we could deduce more homogeneous composites obtained in using the 200 nm PTFE powders. In addition, the temperature dependent dielectric properties and field dependent conductivity of the composites was investigated. It was found that with the good dispersion of the PTFE can suppress the leakage current density in the dielectric composites.
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Silica‐assisted cold sintering of diopside for sustainable cementitious composites
This study explores cold sintering of naturally occurring minerals as supplementary cementitious materials (SCM) or cement analogs, which have the potential to transform the traditional high‐energy, high‐emission cement manufacturing pathways. Diopside (MgCaSi2O6), a natural inosilicate, is used as the model system. As diopside is hard for cold sintering directly (by itself), this study demonstrates that the addition of amorphous silica nanoparticles can enable cold sintering of diopside. The cold‐sintered diopside–silica composites are characterized by X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. The effect of the relative weight percentage of silica added is examined. The relative density of the cold‐sintered composite reaches nearly 90% at 400 MPa and 200°C in 60 min. For specimens with the addition of 30 wt% or more of amorphous SiO2, cold sintering also induces partial crystallization, converting a fraction of amorphous silica to quartz. The crystallization kinetics exhibits a stochastic nature. The Vickers hardness of the cold‐sintered diopside–silica composite increases with increasing amount of silica, whichpromotes cold sintering, reaching ∼3 GPa with 20 wt% or more silica. The diopside–silica composites studied here serve as a model system for metal‐leached silicate mine tailings, which are expected to have nanoporous amorphous silica shells on silicate particles to enable the silica‐assisted cold sintering mechanism discovered in this study.
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- Award ID(s):
- 2328044
- PAR ID:
- 10652518
- Publisher / Repository:
- Journal of the American Ceramic Society
- Date Published:
- Journal Name:
- Journal of the American Ceramic Society
- Volume:
- 109
- Issue:
- 1
- ISSN:
- 0002-7820
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1111/jace.70247
