Flash Joule Heating-Boro/Carbothermal Reduction (FJH-BCTR): An approach for the instantaneous synthesis of transition metal diborides

Abstract

Transition metal diborides (TMB₂), such as ZrB₂ and HfB₂, are a class of ultra-high-temperature ceramics (UHTCs) that have attracted considerable attention due to their performance in extreme environments. Their implementation is burdened by the high energetic requirement of traditional synthetic procedures. Here, we report a novel methodology, termed as Flash Joule Heating-Boro/Carbothermal Reduction (FJH-BCTR), for the instantaneous synthesis of phase-pure sub-micron powders of several TMB₂ and composite within seconds and without any external source of heating. The immediate synthesis is attributed to the Joule heat generated by the current, enabling extremely fast heating and cooling rates and, therefore, avoiding excessive grain growth. The advantages of FJH-BCTR are thoroughly displayed and can be summarized as; highly efficient, it allows a dramatic drop in terms of energy and time; universal, several TMB₂ and composite can be prepared; and flexible, different experimental parameters can be tuned to achieve the desired phase.