Synthesis of Zirconium Diboride Via Carbothermal, Borothermal, and Borocarbothermal Activation Methods

In thepresent research Zirconium diboride powder was synthesized by carbothermal activation (ZrO2+B2O3+C), borothermal activation (ZrO2+B4C), and a compound carbothermal- borothermal, i.e. borocarbothermal, activation (ZrO2+B4C+C) of different compositions at 1550°C for 3 h under argon atmosphere. XRD and SEM studies showed that the ZrB2 powder synthesized by carbothermal activation method has grown with a rod-like morphology. In addition, carbon impurity was observed in the ZrB2 powder. However, in the final product carbon appeared as an element which was omitted by heating at 500°C in an oxidation oven. The powder particles synthesized by this method are larger compared to those produced by other methods. Moreover, there is a lower possibility of sintering of the particles in this method. Synthesis by borothermal method, on the other hand, resulted in appearance of borate as impurity and the rod-like growth of ZrB2. The borate impurity was reduced by washing with ethanol. Synthesis by borocarbothermal route shows a lower amount of particles penetration compared to the borothermal method, which is due to the presence of carbon in the sample. Also, in borocarbothermal synthesis carbon was reduced from the system similar to the carbothermal method. A comparison between the abovementioned routes revealed that activation of borate carbide is a more appropriate method for synthesizing zirconium diboride powder compared to the other techniques.