摘要
非均相沉淀-热还原法制备Fe/Si3N4颗粒复合粉末及常压烧结与热压。通过SEM、TEM、EDS、XRD等方法观察Fe/Si3N4复合粉末的结构形貌,常压烧结与热压后的微观组织。结果表明:复合粉末主要存在Fe相与Si3N4相,结构为纳米薄层Fe均匀包覆Si3N4颗粒;常压烧结与热压的样品微观组织有较大的不同:常压烧结样品存在的主要衍射峰为Fe/Si化合物、SiC和Si3N4,SEM图观察Fe/Si化合物晶粒粗大(2～3μm),分布在Si3N4(1μm左右)相之中;热压样品存在的主要衍射峰为Fe、Fe/Si化合物和Si3N4,SEM图观察Fe/Si化合物晶粒较细(1μm左右),镶嵌在类似玻璃态物质中。并通过热力学分析进行讨论与解释。
Fe/Si3N4 composite powder was synthesized by the heterogeneous precipitation-thermal reduction process, and then pressed into flakes under a pressure of 10 MPa. Flakes were sintered by pressureless and hot-pressing at 1 873K in 0.1 MPa N2. The chemical composition, microstructure and phases of composite powder and sintered flakes were investigated by SEM.TEM.EDS.XRD. It is proved that the microstructures of composite powders is Si3N4 coated by nanometer Fe. The crystal phases of sintered flakes by pressureless are iron silicide, SiC and Si3N4. The crystal phases of the sintered samples by hot -pressing are Fe, iron silicide and Si3N4. It is found that crystal phases flakes by pressureless and hot-pressing are very different and the reason is analyzed by thermodynamics.
出处
《粉末冶金技术》
EI
CAS
CSCD
北大核心
2008年第6期407-412,共6页
Powder Metallurgy Technology
基金
国家自科基金创新研究群体科学基金项目(50721003)
国家自然科学基金项目(50804016)
关键词
包覆
Fe
SI3N4
非均相沉淀
热力学
coating
Fe
Si3N4
heterogeneous precipitation
thermodynamics
