摘要
From the perspective of high-temperature applications,materials with excellent high-temperature mechanical properties are always desirable.The present work demonstrates that the binder-free nanopolycrystalline WC ceramic with an average grain size of 103 nm obtained by high-pressure and hightemperature sintering exhibits excellent mechanical properties at both room temperature and high temperature up to 1000℃.Specifically,the binder-free nanopolycrystalline WC ceramic still maintains a considerably high Vicker hardness H_(V)of 23.4 GPa at 1000℃,which is only 22%lower than the room temperature H_(V).This outstanding thermo-mechanical stability is superior to that of typical technical ceramics,e.g.SiC,Si_(3)N_(4),Al_(2)O_(3),etc.Nanocrystalline grains with many dislocations,numerous low-energy,highly stableΣ2 grain boundaries,and a relatively low thermal expansion coefficient,are responsible for the observed outstanding high-temperature mechanical properties.
基金
supported by the National Key R&D Program of China(Grant No.2018YFA0305900)
the Natural Science Basic Research Program of Shaanxi Province(Grant No.2020JQ870)
the National Natural Science Foundation of China(Nos.52090020,U20A20238,51772260,91963203,51525205)
NSF for Distinguished Young Scholars of Hebei Province of China(E2018203349)
the China Postdoctoral Science Foundation(2017M620097)。