摘要
碳热还原/氮化合成Si3N4在1300～1600℃下N2或N2-H2混合气中进行。反应物由非晶SiO2与C粉以1∶4.5摩尔比混合、压片。产生的CO由红外传感器监测，样品中氧、氮、碳含量由LECO元素分析仪测得，混合物各相由X射线衍射（XRD）检测。SiO2还原反应在1300℃以下开始，速率随温度升高增大；温度高于1570℃时，速率因反应物表面被生成物覆盖降低。由于还原产物CO平衡分压差别小，选择生成Si3N4或SiC的临界温度不明显。碳热还原/氮化法合成氮化硅的原理需进一步探讨。
Carbothermal reduction and nitridation synthesis of silicon nitride was conducted at 1 300～1 600 ℃in nitrogen or nitrogen-hydrogen mixture. Fumed silica was mixed with graph-ite using molar ratio of SiO2∶C=1∶4.5. Powder samples were pressed into pellet before reaction. CO evolution in the process was monitored by an infrared sensor. The oxygen,nitrogen,car-bon content of reacted sample was analysed by LECO element determinators. XRD was used to identify phases formed in the reacted sample. Reduction of SiO2 commenced below 1 300 ℃. The reduction rate increased with increasing temperature,but slowed down when temperature was higher than 1 570℃,since the residual reactant was covered by product. Due to the small difference of the equilibrium CO partial pressure between Si3N4 and SiC formation,the bound-ary temperature was not obvious. The mechanism of carbothermal reduction/nitridation synthe-sis of silicon nitride needs further investigation.
出处
《中国工程科学》
北大核心
2015年第1期62-66,共5页
Strategic Study of CAE
关键词
碳热还原/氮化法
临界温度
生成物选择性
CO平衡分压
carbothermal reduction and nitridation
boundary temperature
selectivity of products
equilibrium CO partial pressure
