尿素法制备纳米氮化锆粉体

利用尿素为固体氮源, 通过尿素分子与ZrCl₄、ZrOCl₂·8H₂O无机锆盐发生络合反应得到Z-U和ZO-U两种ZrN陶瓷的前驱体, 两种前驱体在较低温度下热裂解都可以得到ZrN陶瓷粉体。使用FT-IR对前驱体分子进行了结构分析, 采用TG-DTA跟踪了前驱体的热裂解过程, 并通过XRD和SEM对最终热裂解获得的ZrN产物进行了表征, 探讨了不同锆源制备前驱体的热裂解反应历程及其对产物ZrN的影响。结果显示: 结晶水的存在对络合反应有较大影响, 从而造成两种前驱体分子结构上存在较大差异; 尽管热裂解反应历程相似, 由于前驱体分子结构不同, 获得的ZrN粉体在纯度和形貌上存在较大差异; Z-U前驱体更容易得到纯度高的ZrN纳米粉体。

Synthesis of ZrN Nanopowder via Soft Urea Pathway

High pure ZrN nanopowder was synthesized from Z-U or ZO-U precusors by using ZrCl₄ and ZrOCl₂·8H₂O as zirconium source, urea as solid N source. The preceramic precursors characterized by FT-IR were prepared via coordination between zirconium ions and urea molecules. Both precursors were further pyrolyzed at relatively low temperatures to yield ZrN. XRD and SEM techniques were used to examine the microstructures of the ceramic powders, while TG-DTA was used to study the pyrolysis process. It appears that the crystal water has strong effect on the coordination chemistry of Zr ions, resulting in obvious differences in molecular structures of two precursors. Such structural differences have strong effects on purity and morphologies of the as-prepared ZrN nanopowder. Apparently, the Z-U precursor from ZrCl₄ is more liable to acquire high pure ZrN nanopowder.