Ultraflexible Oxide Fibers with an Amorphous Silica Interfacial Layer on Zirconia Nanograins

Ceramic fibers cannot recover from stretching, bending, and compression at high temperatures owing to their inherent brittleness, which severely restricts their practical applications in harsh environments. However, by designing and regulating grain boundary layers, their inherent brittleness can be effectively decreased, endowing them with high toughness and elasticity at high temperatures. Herein, amorphous silica was incorporated into the grain boundary of zirconia nanograins in fibers to successfully prepare chemically bonded zirconia–silicon biphasic fibers (ZSFs) and fibrous membranes (ZSFMs). ZSFMs exhibit excellent tensile strength; excellent resistance to fatigue from buckling, tension, and compression; low thermal conductivity (20.87 mW·m–1·K–1 at −40 °C and 68.53 mW·m–1·K–1 at 1000 °C); and low density (30–50 mg·cm–3). Moreover, ZSFMs exhibit extraordinary thermal insulation performance. The design of flexible, bendable, and high-strength ZSFMs offers a method for using brittle ceramic components in military and civilian applications and many other fields.