Synthesis of fine ZrB2 powders by solid solution of TaB2 and their densification and mechanical properties

Abstract Effect of in-situ -formed TaB 2 additives on ZrB 2 powders synthesized by borothermal reduction of ZrO 2 with boron together with a small amount of Ta 2 O 5 , and their densification were studied. Without TaB 2 additives, coarse ZrB 2 powders were prepared. However, fine ZrB 2 powders with submicrometric size were synthesized by the solid solution of TaB 2 (≥ 1 mol%). The use of fine ZrB 2 powders synthesized by solid solution of TaB 2 instead of coarse ZrB 2 powders, could improve the densification, refine the microstructure, and increase the hardness of hot-pressed ZrB 2 -SiC ceramics, but decrease the fracture toughness.