Carbothermal synthesis of zirconium diboride (ZrB 2 ) whiskers

In the present investigation, carbothermal synthesis technique is used for the production of ZrB₂ whiskers. The synthesis is carried out by heating the mixture of ZrB₂, H₃BO₃ and carbon black over the temperature range of 1300 to 1700°C in argon atmosphere. Different elements such as Ni, Co and Fe are tested for their role as catalysts. The synthesised powder contains ZrB₂ as the major phase with minor phases of ZrC and B₄C. Whisker yield is found to be low at lower temperatures (<1500°C) and then increases with the pyrolysis temperature. The Ni addition seems more effective as a catalyst than Co or Fe. Shorter length whiskers are found in the case of Co catalyst, whereas use of Fe catalyst shows whisker with rod shape and a special bird's nest type whiskers. The electron microscope study of whisker reveals the presence of various defects.