粉煤灰合成SiAlON粉体研究

Study on synthesizing SiAlON powders from fly ashes

以粉煤灰、石墨粉、氧化铝、二氧化硅等为主要原料,采用碳热还原氮化法合成了SiAlON粉体。研究了Fe2O3含量不同的粉煤灰,即未除铁粉煤灰(Fe2O3的质量分数为4.16%)、酸洗除铁后的粉煤灰(Fe2O3的质量分数几乎为0)和磁选除铁后的粉煤灰(Fe2O3的质量分数为3.46%),配料的m(SiO2)∶m(Al2O3)(分别为1.176、1.55和2.35),碳加入量(分别为理论加入量、过量10%、过量100%和过量150%)以及反应温度(分别为1350℃、1400℃、1420℃、1430℃和1460℃)对合成产物相组成的影响。研究表明:以经过磁选除铁后的粉煤灰(Fe2O3的质量分数为3.46%)为原料,当配料的m(SiO2)∶m(Al2O3)为1.4,碳粉加入量为理论值的2倍(即过量100%)时,于1420℃保温20h合成的产物的主要物相为βSiAlON。

SiAION powders were synthesized successfully using fly ash,graphite,alumina and silica as main starting materials by the carbon thermal reduction and nitration process. And effects of different factors on SiAlON phase compositions were studied,such as Fe2O3 contents of the fly ash,including 4.16% （not eliminating irons） ,near 0 （eliminating irons by pickling） and 3.46% （ eliminating irons by magnetic separation） respectively, m（ SiO2 ）： m（ Al2O3 ） of the mixture （ 1. 176,1.55 and 2.35 ）, addition of carbon （ insufficient, exceeding 10%,100% and 150%） and reaction temperature（1350 ℃,1400 ℃,1420 ℃,1430 ℃,1460 ℃）. Studies showed that the main phase of the obtained product is β-SiAlON when using the fly ash after eliminating irons by magnetic separation （Fe2O3 content is 3.46% ） as starting material ,m（SiO2 ）： rn（Al2O3 ） is about 1.4,carbon powder addition is twice as theory addition（exceeding 100% ） ,synthesizing 1420 ℃ for 20 h.