LI Xueting, WEI Zhifan, ZU Yufei, CHEN Guoqing, FU Xuesong, ZHOU Wenlong
(Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province), School of
Materials Science and Engineering, Dalian University of Technology, Dalian 116085, Liaoning, China)
Abstract: Boride high-entropy ceramics have broad application prospects because of their excellent mechanical properties, high oxidation resistance and promising electrochemical properties. (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2 high-entropy ceramics were prepared through boro/carbothermal reduction combined with spark plasma sintering technology. Phase composition and electrochemical properties of the as-sintered samples were studied. It is demonstrated that the Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2 high-entropy ceramic powders obtained at 1600 ℃, 1650 ℃ and 1700 ℃ and the bulk ceramics sintered at 2000 ℃ did not exhibit single hexagonal structure high-entropy phase. The as-sintered bulk had small content of second phase (Hf, Zr)B2 and (Hf, Zr)O2distributed in between the high-entropy phase. As the reduction temperature is increased, the crystallinity of the powder is increased. The sintered (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2 ceramics have a relative density of 96% and a hardness of (23.4 ± 1.2) GPa. In addition, the (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2 ceramics exhibited high energy storage performance and corrosion resistance. At a current density of 0.1 mA·cm−2 in 3.5 wt.% NaCl, the charge/discharge ratio capacitance can reach 50.29/44.50 F·cm−2 and the coulombic efficiency can be >87%, satisfying the standards of the electrode material for supercapacitors.
Key words: boride; high-entropy ceramics; phase structure; electrochemical performance