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Cold Sintering Breaks Temperature Barriers: Aqueous‐NaOH‐Driven Densification of Amorphous SiHfBN Ceramics at 250°C.

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Bibliographic Details
Title:	Cold Sintering Breaks Temperature Barriers: Aqueous‐NaOH‐Driven Densification of Amorphous SiHfBN Ceramics at 250°C.
Authors:	Li, Wei^1,2,3 (AUTHOR), Jiang, Tianshu² (AUTHOR), Ding, Jinxue² (AUTHOR), Widenmeyer, Marc² (AUTHOR), Feldmann, Laura² (AUTHOR), Zhang, Yaohao² (AUTHOR), Zhuo, Fangping² (AUTHOR), Xie, Wenjie² (AUTHOR), Weidenkaff, Anke² (AUTHOR), Molina‐Luna, Leopoldo² (AUTHOR), Riedel, Ralf² (AUTHOR), Yu, Zhaoju^1,4 (AUTHOR) zhaojuyu@xmu.edu.cn
Source:	Journal of the American Ceramic Society. Jun2026, Vol. 109 Issue 6, p1-8. 8p.
Subjects:	Sintering, Sodium hydroxide, Amorphous substances, Ceramic engineering, Thermal stability, Ceramics, Mechanical behavior of materials
Abstract:	Conventional ceramic processing often requires temperatures above 1500°C, locking the field into high energy costs and limited compositional flexibility. Here, we defy this paradigm by demonstrating the cold sintering of amorphous SiHfBN ceramics at only 250°C. Using a transient aqueous NaOH medium, amorphous SiHfBN powders derived from a single‐source polymeric precursor are transformed into dense monoliths (≈ 88% relative density) through a synergistic combination of lubrication‐assisted particle rearrangement and surface‐driven hydrolysis‐condensation reactions. The resulting ceramics achieve a Vickers hardness of 2.8 GPa and compressive strength of 114 MPa, rivaling porous Si3N4 processed above 1700°C. They also exhibit good thermal stability and oxidation behavior, achieving a mass loss of only 0.25% at 1000°C in air. Their ultralow thermal conductivity (0.7–1.3 W m−1·K−1), structural integrity, and stability up to 700°C establish a new processing frontier for amorphous Si‐based ceramic materials. This work redefines the boundaries of ceramic fabrication, positioning cold sintering as a viable route for future energy‐efficient manufacturing of high‐performance nonoxide ceramics. [ABSTRACT FROM AUTHOR]
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Database:	Engineering Source

Description
Abstract:	Conventional ceramic processing often requires temperatures above 1500°C, locking the field into high energy costs and limited compositional flexibility. Here, we defy this paradigm by demonstrating the cold sintering of amorphous SiHfBN ceramics at only 250°C. Using a transient aqueous NaOH medium, amorphous SiHfBN powders derived from a single‐source polymeric precursor are transformed into dense monoliths (≈ 88% relative density) through a synergistic combination of lubrication‐assisted particle rearrangement and surface‐driven hydrolysis‐condensation reactions. The resulting ceramics achieve a Vickers hardness of 2.8 GPa and compressive strength of 114 MPa, rivaling porous Si3N4 processed above 1700°C. They also exhibit good thermal stability and oxidation behavior, achieving a mass loss of only 0.25% at 1000°C in air. Their ultralow thermal conductivity (0.7–1.3 W m−1·K−1), structural integrity, and stability up to 700°C establish a new processing frontier for amorphous Si‐based ceramic materials. This work redefines the boundaries of ceramic fabrication, positioning cold sintering as a viable route for future energy‐efficient manufacturing of high‐performance nonoxide ceramics. [ABSTRACT FROM AUTHOR]
ISSN:	00027820
DOI:	10.1111/jace.70944