(東北大學 材料與冶金學院， 沈陽 110004)
摘 要: 以納米SiO2，Al(OH)3和碳黑為原料，在1400℃N2氣氛下采用碳熱還原氮化法合成出O′-Sialon粉。繪出了1400℃時體系的優(yōu)勢區(qū)域圖，用XRD分析法測定了產(chǎn)物相組成及相對含量，用TEM觀察了產(chǎn)物的形貌，并用EDX分析法測定了產(chǎn)物中O′-Sialon的Si和Al摩爾比。在此基礎上，研究了保溫時間和添加劑含量對合成過程的影響，對合成過程機理進行了探討。結果表明：保溫7h，含3%添加劑的試樣中O′-Sialon含量最高，達70%左右，O′-Sialon中z值基本達到0.3。添加劑含量的增加有利于Al2O3向O′-Sialon中固溶。SiO是碳熱還原氮化過程的中間產(chǎn)物，SiO的揮發(fā)導致體系較大的質量損失和Al2O3的殘存。保溫時間超過8h，體系氣氛的改變使O′-Sialon分解轉化為β′-Sialon。
關鍵字: O′-Sialon；碳熱還原氮化；合成機理
carbothermal reduction-nitridation
JIANG Tao，WANG Wenzhong
（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
