以硅粉和Si3N4粉体为反应剂, 偶氮二甲酰胺(AC发泡剂)为添加剂, 利用燃烧合成技术在较低氮气压力下制备了高α相含量的Si3N4粉体. 采用X射线衍射和扫描电镜分别对产物的物相组成及显微结构进行了表征, 研究了AC发泡剂对α相Si3N4粉体的形成和产物颗粒形貌的影响. 结果表明, AC发泡剂能促进硅粉快速氮化, 产物中α-Si3N4的含量随着AC发泡剂添加量的增加而增加. 当AC发泡剂的添加量为24wt%时, 产物中α-Si3N4的含量高达85.2wt%. 对AC发泡剂作用下的燃烧合成Si3N4的反应机理做了初步探讨, 研究表明: AC发泡剂的分解产物N2、CO、NH3不仅增加了坯体的透气性, 而且改变了燃烧反应的传热和传质路线, 从而促进了硅粉快速氮化和α-Si3N4粉体的生成.
Combustion synthesis (CS) of high content of α-Si3N4 powders was carried out using Si and Si3N4 powders as reactants with the addition of diazenedicarboxamide (AC) at a relatively low N2 pressure of 3 MPa. The phase compositions and microstructure of products were characterized by XRD and SEM. Effects of AC contents on the phase compositions and Si3N4 particles morphology were studied. In addition, the reaction mechanisms were discussed. The results indicated that the additive AC promoted the nitridation of Si. The α-Si3N4 contents in the combustion-synthesized products showed great dependence on the contents of AC added in the reactants, which reached 85.2wt% adding with 24wt% AC. Meanwhile, impurities such as SiC, Si2N2O could be found in the final products when more than 12wt% AC agent was added. Poor dispersibility of Si3N4 particles would be more serious with increasing AC contents in the reactants. N2, CO and NH3 produced by decomposition of AC leaded to a change of compact porosity, thermal convection and mass transfer processes, which was responsible for the increasing contents of α-Si3N4 and the discrepancy morphology of the products.
参考文献
| [1] | |
| [2] | |
| [3] | |
| [4] | |
| [5] | |
| [6] | |
| [7] | Shibata N, Pennycook S, Gosnell T, et al. Observation of rare-earth segregation in silicon nitride ceramics at subnanometre dimensions. Nature, 2004, 428: 730-733.[2] LUO Min, CHENG Jia, MA Jing, et al. Biomimetic synthesis of porous Si3N4 ceramics. Journal of Inorganic Materials, 2008, 23(4): 763-768.[3] WANG Yong, WO Yin-Hua, YAO Kui-Hong, et al. CVD Synthesis of silicon nitride (SiN) nanopowders in a novel two-stage fluidized bed reactor. Journal of Inorganic Materials, 2006, 21(1): 41-45.[4] LIU Xue-Jian, HUANG Zhi-Yong, HUANG Li-Ping, et al. Mechanical properties and microstructure of silicon nitride ceramics by pressureless sintering. Journal of Inorganic Materials, 2004, 19(6): 1282-1286.[5] Riley F L. Silicon nitride and related materials. J. Am. Ceram. Soc., 2000, 83(2): 245-265.[6] Zakorzhevskii V V, Borovinskaya I P. Some regularities of synthesis &alpha |
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