Facile one‐step high‐temperature spray pyrolysis route toward metal carbide nanopowders
Facile one‐step high‐temperature spray pyrolysis route toward metal carbide nanopowders
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DOI：
10.1111/jace.15785
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发表时间：
2018-06
影响因子：
3.9
通讯作者：
Junheng Xing;Paniz Foroughi;Alexander Franco Hernandez;A. Behrens;Zhe Cheng
中科院分区：
文献类型：
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作者：
Junheng Xing;Paniz Foroughi;Alexander Franco Hernandez;A. Behrens;Zhe Cheng
超微高温陶瓷（UHTC）粉体在许多领域都有非常重要的应用。在这项工作中，采用一种简单的高温喷雾热解（HTSP）方法，从金属前驱体（hfcl4或TaCl5）的有机溶剂（如乙醇或1 -戊醇）溶液开始，合成HfC和TaC UHTC纳米粉末。提出在高温高温还原过程中，前驱体溶液液滴将连续经历快速干燥、热分解（即去除H2、H2O和CO等低分子量物质），最后进行原位碳热还原（CTR）过程，生成金属碳化物纳米粉体。SEM显示，所得材料为均匀且分离的纳米颗粒（~90 nm），而TEM显示碳化物（例如HfC）纳米颗粒实际上更小（~10 ~ 20 nm），并且嵌入在过量溶剂分解的无定形碳中。研究发现，在不同的工艺参数下，使用的有机溶剂和金属前驱体浓度对金属碳化物的形成有较大的影响。此外，较低的HTSP温度（HfC≤~1500°C）只导致氧化物-碳混合物，而较高的温度（≥~1650°C）促进碳化物的形成。本研究开发的HTSP方法简单、低成本、高效，并有可能进一步优化，用于未来超细UHTC纳米粉末的大规模制造。
Fine ultrahigh‐temperature ceramic (UHTC) powders have found very important applications in many fields. In this work, a facile high‐temperature spray pyrolysis (HTSP) approach is implemented for the synthesis of HfC and TaC UHTC nanopowders starting from organic solvent (e.g., ethanol or 1‐pentanol) solutions of metal precursors (HfCl4or TaCl5). It is proposed that, during HTSP, the precursor solution droplets would continuously undergo rapid drying, thermolysis (i.e., removal of low molecular weight species such as H2, H2O, and CO), and finally in situ carbothermal reduction (CTR) process to give rise to metal carbide nanopowders. The as‐obtained materials are shown by SEM as uniform and separated nanoparticles (~90 nm), whereas TEM reveals the carbide (e.g., HfC) nanoparticles are actually even smaller (~10‐20 nm) and embedded in amorphous carbon from excess solvent decomposition. It is found that among different processing parameters, the organic solvent used and the metal precursor concentration could largely influence the formation of metal carbide. In addition, lower HTSP temperatures (≤~1500°C for HfC) only lead to oxide‐carbon mixtures while higher temperatures (≥~1650°C) promote carbide formation. The HTSP method developed in this work is simple, low‐cost and efficient, and could potentially be optimized further for future large‐scale manufacturing of ultrafine UHTC nanopowders.