Effect of hafnium oxide on continuous aluminum oxide-mullite-hafnium oxide composite ceramic fibers

Abstract

The Al2O3-mullite-HfO2 (AMH) ceramic fiber with a 20 wt.% of HfO2 has demonstrated good tensile strength and good high-temperature stability due to the tiny diameter and small grains even at high temperatures. To investigate the effect of HfO2 on crystal behavior and high-temperature performance, continuous AMH ceramic fibers with different HfO2 contents (0 wt.%, 10 wt.%, and 50 wt.%) were prepared by melt-spinning of polymer precursors. The effect of HfO2 on the crystal form transition process, mechanical properties, and high-temperature resistance of AMH fibers was studied by in-situ XRD and STEM. The AMH fibers with 50 wt.% HfO2 had the highest strength retention rate of 78.33% after heat treatment at 1200°C for 0.5 h. After 0.5 h of heat treatment at 1500°C, the grain size of the AMH fibers with 50 wt.% HfO2 was still less than 200 nm.