Synthesis of ZrB2–SiC composite powder in air furnace

Abstract The formation of ZrB 2 through reaction of ZrO 2 with B 4 C without adding carbon has been studied at different temperatures between 1020 °C and 1600 °C. The ratio of ZrO 2 /B 4 C was optimized to produce a single phase ZrB 2 . By introducing Si species into reaction mixture, composite powders of ZrB 2 –SiC, ZrB 2 –SiC–B 4 C are produced. The SiC in composite powder was well distributed in ZrB 2 matrix and the powder was successfully air plasma coated on to CC composite. To scale up the process in a continuous furnace, the reactant mixture of (ZrO 2 +B 4 C+Si) was rapidly heated by suddenly introducing the reactant compact in to an air furnace held at different temperatures between 900 °C and 1700 °C. The extent of reaction after short duration of 3–5 min has been studied. The formation of ZrB 2 and SiC was confirmed through XRD and SEM analyses in samples reacted at and above a temperature of 1300 °C. Though coarsening due to agglomeration was observed with increase in reaction temperature from 1300 °C to 1700 °C, sub-micron sized particles were seen existing even after reaction at 1700 °C. A possible furnace design for continuous operation has been proposed.