Oxygen‐Containing SiBNO Ceramic Fibers With Superior High‐Temperature Stability up to 1700°C

ABSTRACT

Further improving the thermal stability of microwave‐transparent ceramic fibers is still an interesting but challenging project. In this work, we prepared a kind of amorphous SiBNO ceramic fibers with an oxygen content of 10.0 wt%. The oxygen is mainly distributed in SiN _x O _y ( x  +  y = 4) and BN _x O _y ( x  +  y = 3) phases with complex chemical bonding. The oxygen‐containing phase showed superior thermal stability up to 1700°C, enhancing the thermal stability of SiBNO fibers. Finally, oxygen‐containing SiBNO fibers could remain almost amorphous and show nearly 100% strength retention after annealing at 1700°C in an N ₂ atmosphere for 1 h, showing superior thermal stability compared to Si ₃ N ₄ and SiBN fibers with very low oxygen content. This interesting finding may challenge the conventional notion that oxygen is harmful to the thermal stability of Si‐based ceramics and should provide a new strategy for fabricating advanced ceramic materials with excellent high‐temperature stabilities.