One-pot syntheses and characterization of zirconium carbide microspheres by carbon microencapsulation

Due to the extremely harsh reaction conditions, it is very difficult to control the particle morphology during the synthesis of ZrC, a well-known ultra high temperature ceramic material. In this paper, carbon encapsulated zirconia microspheres (ZrO2@C) are synthesized via two consecutive hydrothermal reactions in one pot. After carbothermal reduction, ZrC particles with controlled spherical morphology can be prepared. The spherical morphology suggests that carbon diffuses into zirconia during carbothermal reduction. The influences of reactant concentrations, reaction time and temperature on the microencapsulation process are also investigated. Meanwhile, as a comparison, zirconia coated carbon microspheres (C@ZrO2) are also prepared, which results in ZrC particles with layered structure.