Preparation of (Ti_0.2Zr_0.2Hf_0.2Nb_0.2Ta _0.2)C high-entropy ceramic nanopowders via liquid-phase precursor

Using citric acid, ethylene glycol, ZrOCl2 center dot 8H(2)O, HfOCl2 center dot 8H(2)O, TiCl4, NbCl5, and TaCl5 as raw materials, the (Ti(0.2)Zr(0.)2Hf(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 center dot s). At a low pyrolysis temperature of 1600degree celsius, single-phase (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)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.