高岭土在碳热还原氮化过程中的相变

Phase transformations in the process of carbothermal reduction nitridation react ion of Kaolin

系统研究了苏州高岭土碳热还原氮化合成SiAlON过程在不同温度下的相变。对试样的XRD、SEM以及EDXA分析结果表明 ,1 30 0℃之前 ,试样中没有氮化物生成 ,物相为莫来石、石英和方石英 ;1 30 0℃时 ,高岭土开始发生氮化反应 ,生成过渡型SiAlON和β SiAlON。此时 ,石英和方石英相基本消失 ;1 4 0 0℃时 ,过渡型SiAlON、β SiAlON和X SiAlON三相共存 ,β SiAlON有所增多并有少量刚玉相生成 ;从 1 4 50℃到 1 550℃ ,Z值为 3的β SiAlON成为惟一的氮化产物 ,与少量SiC和刚玉相并存。莫来石在 1 50

Phase transformations at different temperatures in the carbothermal reduction ni tridation process of synthesizing Sialon from Suzhou Kaolin were studied by XRD ,SEM and EDXA. The results show that there are no nitride formed but quartz,cr istobalite and mullite in the specimen below 1300 ℃,and nitridation reaction b egins at 1300 ℃ in Kaolin with formation of transitional type Sialon and β-S ialon phases and disappearing of quartz and cristobalite;At 1400 ℃,transitional type Sialon,β-Sialon(Z=3) and X-SiAlON coexist,β-Sialon amount in creases and a little amount of corundum forms; The only nitridation product of β-Sialon with some corundum and silicon carbide are the final products from 14 50 ℃ to 1550 ℃;Mullite disappears totally at 1500 ℃.