(东北大学 材料与冶金学院， 沈阳 110004)
摘 要: 以纳米SiO2，Al(OH)3和碳黑为原料，在1400℃N2气氛下采用碳热还原氮化法合成出O′-Sialon粉。绘出了1400℃时体系的优势区域图，用XRD分析法测定了产物相组成及相对含量，用TEM观察了产物的形貌，并用EDX分析法测定了产物中O′-Sialon的Si和Al摩尔比。在此基础上，研究了保温时间和添加剂含量对合成过程的影响，对合成过程机理进行了探讨。结果表明：保温7h，含3%添加剂的试样中O′-Sialon含量最高，达70%左右，O′-Sialon中z值基本达到0.3。添加剂含量的增加有利于Al2O3向O′-Sialon中固溶。SiO是碳热还原氮化过程的中间产物，SiO的挥发导致体系较大的质量损失和Al2O3的残存。保温时间超过8h，体系气氛的改变使O′-Sialon分解转化为β′-Sialon。
关键字: O′-Sialon；碳热还原氮化；合成机理
carbothermal reduction-nitridation
（School of Materials and Metallurgy，
Northeastern University， Shenyang 110004，China）
Abstract:O′-Sialon powder was synthesized by means of carbothermal reduction-nitridation with nano SiO2， Al(OH)3 and carbon black as raw materials at 1400℃ in N2 atmosphere. Thermodynamic predomination region diagram for the Si3N4/Si2N2O/SiC/SiO2 system at 1400℃ was presented. Phase composition of reaction products was determined by XRD. Morphology of the synthesized O′-Si alon was observed by TEM and molar ratio of Si to Al was determined by EDX. Effects of holding time and addtive content on synthesis process was studied and synthesis mechanism was discussed in detail. It shows that when the holding time is 7h and additive content is 3%，the content of O′-Sialon in the sample reaches the highest value of 70% or so and the value of z, solid solubility of Al2O3 in O′-Sialon, is near 0.3. The increase of additive content is favorable for the solid state solution of Al2O3 into O′-Sialon. SiO is an intermediate product for the process of carbothermal reduction-nitridation. Volatilization of SiO results in great mass loss of the samples and the remaining of Al2O3 in reaction products. If the holding time is above 8h，O′-Sialon will be converted into β′-Sialon because of the change of atmosphere in the system.
Key words: O′-Sialon; carbothermal reduction-nitridation; synthesis mechanism
