Fine‐Grain High‐Performance Densified Oxide Fibers Produced by Open Ultrafast High‐Temperature Sintering

Abstract The considerable grain growth occurring during the long‐term high‐temperature sintering of polycrystalline oxide fibers negatively affects their mechanical properties, which highlights the need for alternative sintering methods. Herein, open ultrafast high‐temperature sintering (OUHS) in air, characterized by rapid heating/cooling (>10000 K min −1 ) and a short high‐temperature holding time (<10 s), is used to produce 3 mol% yttria‐stabilized zirconia continuous fibers with coherent boundaries forming robust connections between fine grains. The tensile strength of these fibers (2.33 GPa on average, sintering temperature = 1673 K) notably exceeds that of their counterparts produced by traditional sintering (1.17 GPa). The effects of pores on fiber mechanical properties are analyzed using experimental and theoretical methods. For a versatility demonstration, OUHS is applied to several types of polycrystalline oxide fibers (HfO 2 , Al 2 O 3 , TiO 2 , Y 2 O 3 , and La 2 Zr 2 O 7 ), considerably improving their mechanical properties and enabling crystalline phase control, which demonstrates the suitability of this procedure for the development of high‐performance materials.