Single-Step Synthesis Process for High-Entropy Transition Metal Boride Powders Using Microwave Plasma
| Autor: | Deepa Kodali, Kallol Chakrabarty, Shane A. Catledge, Bria C. Storr, Vijaya K. Rangari, Paul A. Baker |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Technology
Materials science microwave Materials Science (miscellaneous) Analytical chemistry 02 engineering and technology Boron carbide TP1-1185 ceramics 01 natural sciences Vacuum furnace chemistry.chemical_compound high-entropy Boride Phase (matter) 0103 physical sciences Ceramic Ball mill Powder mixture plasma 010302 applied physics Chemical technology 021001 nanoscience & nanotechnology boride chemistry visual_art Ceramics and Composites visual_art.visual_art_medium 0210 nano-technology Microwave |
| Zdroj: | Ceramics, Vol 4, Iss 20, Pp 257-264 (2021) |
| ISSN: | 2571-6131 |
| Popis: | A novel approach is demonstrated for the synthesis of the high entropy transition metal boride (Ta, Mo, Hf, Zr, Ti)B2 using a single heating step enabled by microwave-induced plasma. The argon-rich plasma allows rapid boro-carbothermal reduction of a consolidated powder mixture containing the five metal oxides, blended with graphite and boron carbide (B4C) as reducing agents. For plasma exposure as low as 1800 °C for 1 h, a single-phase hexagonal AlB2-type structure forms, with an average particle size of 165 nm and with uniform distribution of the five metal cations in the microstructure. In contrast to primarily convection-based (e.g., vacuum furnace) methods that typically require a thermal reduction step followed by conversion to the single high-entropy phase at elevated temperature, the microwave approach enables rapid heating rates and reduced processing time in a single heating step. The high-entropy phase purity improves significantly with the increasing of the ball milling time of the oxide precursors from two to eight hours. However, further improvement in phase purity was not observed as a result of increasing the microwave processing temperature from 1800 to 2000 °C (for fixed ball milling time). The benefits of microwave plasma heating, in terms of allowing the combination of boro-carbothermal reduction and high entropy single-phase formation in a single heating step, are expected to accelerate progress in the field of high entropy ceramic materials. |
| Databáze: | OpenAIRE |
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