Preparation of (Ti _0.2 Zr _0.2 Hf _0.2 Nb _0.2 Ta _0.2 )C high‐entropy ceramic nanopowders via liquid‐phase precursor

Abstract

Abstract Using citric acid, ethylene glycol, ZrOCl 2 ·8H 2 O, HfOCl 2 ·8H 2 O, TiCl 4 , NbCl 5 , and TaCl 5 as raw materials, the (Ti 0.2 Zr 0.2 Hf 0.2 Nb 0.2 Ta 0.2 )C high‐entropy ceramic precursor was prepared by Pechini coordination polymerization method. The precursor and pyrolysis products were analyzed and characterized by different methods. The results showed that the precursor formed a chelate structure, which greatly improved the stability of the precursor, and was clear and transparent with moderate viscosity (30–50 mPa·s). At a low pyrolysis temperature of 1600°C, single‐phase (Ti 0.2 Zr 0.2 Hf 0.2 Nb 0.2 Ta 0.2 )C high‐entropy ceramic nanopowders with a ceramic yield of 50.8% can be obtained. The high‐entropy ceramic powder has high purity, a particle size of about 140–200 nm, and uniform element distribution. It is suitable for introduction into fiber‐reinforced ceramic matrix composite by precursor infiltration and pyrolysis (PIP) process.