摘要
为分析反应烧结氮化硅结合碳化硅(Si3N4-SiC)材料中微观结构和氮化硅分布不均匀的原因,对在隔焰燃气氮化梭式窑中应用反应烧结氮化方法制备的氮化硅结合碳化硅复合材料进行结构研究和热力学分析。结果表明:材料中的氮化硅以纤维状和柱状两种形状存在。Si的氮化机理为:Si首先被氧化成气态SiO,降低了体系的氧分压,当氧分压足够低时,Si与N2直接反应形成柱状Si3N4,气态SiO亦可与N2反应生成氮化硅,这是一个气-气反应,故生成的Si3N4为纤维状。氮化反应前SiO主要分布于材料孔隙和表面,因而生成的氮化硅分布不均匀,导致了反应烧结Si3N4-SiC材料结构的不均匀。
In order to investigate the reason of uneven microstructure and non-uniform distribution of Si3N4 in Si3N4-SiC materials,both microstructure and thermodynamics of Si3N4-SiC composite materials were analyzed,which were prepared by nitriding reaction sintering in flame-isolation nitridation shuttle kiln.The results show that Si3N4 exists in fibrous state and column state.Nitridation mechanism of silicon is as follows： silicon is oxidized to form gaseous SiO firstly,oxygen partial pressure is reduced in the system,silicon reacts with nitrogen directly to form column Si3N4 while the system oxygen partial pressure is low enough.SiO reacts with nitrogen to form Si3N4 also,which is a gas-gas reaction,so the fibrous Si3N4 is formed.Gaseous SiO mainly distributes in pores and surfaces before nitridation,and thus it causes the non-uniform distribution of Si3N4 and uneven microstructure of reaction-sintered Si3N4-SiC materials.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2011年第3期447-451,共5页
Journal of The Chinese Ceramic Society
基金
北京市教育委员会共建专项资助
关键词
反应烧结
氮化硅
碳化硅
氮化反应机理
直接氮化
一氧化硅氮化
reaction sintering
silicon nitride
silicon carbide
nitridation mechanism
direct nitridation
silicon monoxide nitridation
