Transformation of metallic polymer precursor into nanosized HfTaC2 ceramics

作者：Sun, Yanan; Yang, Chunming; Lu, Yan; Chen, Fenghua^*; Han, Weijian; Qiu, Wenfeng; Ye, Li; Li, Xiuhong; Zhao, Tong^*

来源：Ceramics International, 2020, 46(5): 6022-6028.

DOI：10.1016/j.ceramint.2019.11.059

• Ultra high temperature ceramics
• Hf6Ta2O17
• In-situ XRD
• Synchrotron

Polymeric precursor for HfTaC2 ceramic was prepared by coordination reaction between metal alkoxides and acetylacetone, subsequent hydrolysis, and blend with oligomeric novolac carbon sources. The phase analysis and microstructure study were conducted using X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). It showed that after pyrolyzed at 1450 degrees C for 90 min, HfTaC2 was obtained with particle size similar to 50 nm and uniform elemental distribution. Phase transition from precursor to ceramic was studied by in situ XRD measurements at temperatures from 800 to 1200 degrees C. In the early stage, oxide solid solution Hf6Ta2O17 was firstly detected at similar to 950 degrees C, followed by Ta2O5 and TaO. As temperature was raised, signals for TaO and Hf6Ta2O17 gradually weakened and disappeared, while those for other phases strongly strengthened. Furthermore, formation of HfxTayCz solid solution was monitored and confirmed by peak migration during 1300 degrees C isothermal treatment. When the sample was pyrolyzed at 1450 degrees C, solid solution HfxTayCz was detected at different holding time. Phase structure at 90 min was the closest to standard HfTaC2 with particle size D-v (90) similar to 200 nm.

• 单位
  中国科学院; 中国科学院研究生院