HfC前驱体的合成及其裂解行为研究

Hf C Precursor: Synthesis and Pyrolysis Behavior

以Hf Cl_4、乙酰丙酮、无水甲醇、对苯二酚为原料,采用一锅法合成了Hf C陶瓷前驱体,通过前驱体裂解制备得到了Hf C陶瓷粉体。采用XRD、FTIR、SEM/EDS、TEM、SAED等分析手段对裂解产物的组成、形貌和微观结构进行了分析和表征,利用TG-DSC和TG-MS对前驱体的裂解行为进行了研究。结果表明:Hf C前驱体在600℃左右开始陶瓷化,在1300℃左右开始形成Hf C陶瓷相,在1500℃及以上完全转化为Hf C陶瓷及自由碳。Hf C陶瓷相具有单晶结构,颗粒粒径在50~100 nm之间。Hf C陶瓷相的形成基于前驱体在低温段裂解形成的Hf O_2的碳热还原反应,裂解过程中形成的自由碳抑制了Hf C晶体的生长。

Hafnium carbide ceramic powders were prepared by pyrolysis of a novel precursor, which was synthesized via one pot method using hafnium tetrachloride, acetylacetone, methanol, and hydroquinone as raw materials. The composition, morphology and microstructure of the pyrolysis products were characterized by XRD, FTIR, SEM/EDS, TEM, and SAED. The pyrolysis behavior of the obtained Hf C precursor was investigated by TG-DSC and TG-MS. The results show that the ceramization of the Hf C precursor starts at about 600℃, and the formation of Hf C ceramics is initiated at about 1300℃. At temperature above 1500℃, the precursor completely transforms into Hf C ceramics and free carbon. The as-obtained Hf C phase has a single crystal structure and the size of the Hf C particles ranges from 50 to 100 nm. Formation of the Hf C ceramics can be attributed to the carbothermal reduction reaction of the Hf O2, which is produced by pyrolysis of the precursor at a relative low temperature. The growth of the Hf C crystals is retarded by free carbon formed during pyrolysis of the precursor.