燃烧合成Si_3N_4和SiC复相材料的相稳定性热力学分析  

Thermodynamic Analysis of Phases Stability for Combustion Synthesis Si_3N_4 and SiC Composite Raw Materials

作　　者：陈松林[1,2] 袁林[1] 冯中起[1] 刘锡俊[1] 曾鲁举[1] 杨筠[3] 李江涛[3] 

机构地区：[1]中国建筑材料科学研究总院瑞泰科技股份有限公司,北京100024 [2]北京科技大学材料学院,北京100083 [3]中国科学院理化技术研究所,北京100190

出　　处：《材料科学与工程学报》2012年第5期659-665,共7页Journal of Materials Science and Engineering

基　　金：国家自然科学基金资助项目(50172005);"863"国家高技术研究发展计划资助项目(2001AA333070)

摘　　要：为了提高Si3N4产率和降低成本,采用硅粉、氮气作为原料,碳、二氧化硅作为稀释剂,卤化铵作为化学激励剂,通过机械活化和化学激励法燃烧合成制备Si3N4和SiC复相原料。热力学分析表明:特定的工艺条件下氧化硅和碳替代氮化硅作为稀释剂,当氧化硅和碳含量约30wt%时,能得到氮化硅和碳化硅复合陶瓷粉体。以碳的活度为1计(ac=1),燃烧合成时两者稳定共存的温度为1647K;同时,增大氮气压力和降低氧分压是硅粉完全氮化的条件,而不宜提高合成温度。当满足特定工艺条件时(原料加入量为9%Si3N4及15%淀粉和SiO2的混合物、氮气压力大于3MPa、5小时磨研),燃烧合成产物的主晶相为Si3N4、SiC和Si2N2O,而无游离硅,此产物是烧结Si3N4和SiC复合陶瓷或制备Si3N4结合SiC耐高温材料的理想原料。In order to enhance productivity and reduce cost,Si3N4 and SiC composite powder was synthesized by combustion after mechanical activation and chemical incensitive.Silicon powder and nitrogen gas were used as raw materials,carbon and silicon dioxide as diluent,and ammonium halide as chemical incentive agent.Thermodynamic analysis shows that silicon oxide and carbon as diluents to replace silicon nitride needs specific process conditions.Only when silica and carbon content are about 30 wt%,silicon nitride and silicon carbide composite powder can form.Assuming the carbon activity is 1（ac=1）,the equilibrium temperature for the coexistence of Si3N4 and SiC in the combustion synthesis system is 1647K.At the same time,the complete nitrogenation of silicon powder needs high nitrogen partial pressure and low oxygen partial pressure,but not high temperature.When the necessary and appropriate process condition（9% Si3N4 and 15% mixture of starch and SiO2 content,more than 3MPa nitrogen pressure,5 hours milling） is met,the combustion synthesis product is free of silicon,but mainly composed of Si3N4,SiC and Si2N2O crystal phases,,which is an ideal composition as the raw materials of Si3N4-SiC dual phase ceramics and Si3N4 bonded SiC refractory.

关 键 词：SI3N4 SIC 燃烧合成 相稳定性 热力学 

分 类 号：TQ174[化学工程—陶瓷工业]