采用煤矸石和用后Al_2O_3-SiC-C铁沟料合成β-SiAlON

Synthesis of β-SiAlON from wasted Al_2O_3-SiC-C castables and coal gangue

在热力学分析的基础上,以用后Al2O3-SiC-C铁沟料、煤矸石和活性炭为主要原料,采用碳热还原氮化法合成了β-SiAlON。详细讨论了合成温度(1 723和1 823 K)、活性炭加入量(理论需碳量、过量15%、过量30%和过量45%)、Si与Al元素摩尔比(分别为3:3,3.5:2.5和4:2)和煤矸石种类(低碳煤矸石和高碳煤矸石)对合成β-SiAlON的影响,并采用XRD、SEM和EDS等对合成产物进行分析。结果表明:(1)当合成温度由1 723 K增加到1 823 K时,合成后试样中β-SiAlON相含量增加,O’-SiAlON和α-Al2O3的含量降低;(2)加入过量的活性炭有利于合成后试样中β-SiAlON相含量的增加;(3)随着Si、Al元素摩尔比的增大,合成后试样中β-SiAlON相含量增多;(4)采用低碳煤矸石的试样中β-SiAlON相含量高于采用高碳煤矸石的,其原因是配料时前者中配入的活性炭更多,而活性炭的活性较高,更有利于促进碳热还原氮化反应的进行。

β-SiAlON was synthesized using wasted Al2O3-SiC-C and coal gangue as starting materials by carbonthermal reduction-nitridation method,based on thermodynamic analysis.The influence factors such as synthesizing temperatures（1 723 K and 1 823 K）,the active carbon additions（stoichiometric,15% excessive,30% excessive and 45% excessive）,mole ratios of Si/Al（3：3,3.5：2.5 and 4：2） and coal gangue types（low-carbon and high-carbon） were investigated,and the phase composition and microstructure of the synthesized products were also analyzed by XRD,SEM and EDS.The results indicated that：（1）When the synthesizing temperature increased from 1 723 K to1 823 K,the content of β-SiAlON in specimen increased,but the content of O＇-SiAlON and Al2O3 decreased;（2）Excessive active carbon addition could benefit the increase of β-SiAlON;（3）The β-SiAlON phase increased with increasing of the mole ratio of Si/Al;（4）The β-SiAlON content in the specimen using low-carbon coal gangue was higher than that in the specimen using high-carbon one,because the specimen using low-carbon coal gangue was added more active carbon,which could benefit the carbonthermal reduction nitridation.