还原剂复合方式对高岭土还原氮化反应的影响

Effect of reductant compounding mode on reduction and nitridation reaction of kaolin

为了探究不同还原剂及还原方式对高岭土还原氮化过程的影响,实现高岭土的高附加值利用。以高岭土细粉、金属铝粉、单质硅粉和炭黑为主要原料,采用碳-铝还原(试样CA)、碳-硅还原(试样CS)、碳-铝-硅共还原(试样CAS)的方法制备含氮化合物粉体,通过XRD和SEM对试样的物相组成和显微结构进行分析。结果表明:相比于碳-硅复合方式,碳-铝及碳-铝-硅复合方式还原能力更强;还原剂复合方式及反应温度在很大程度上共同影响了高岭土的还原氮化反应进程。硅、铝及碳同时引入有利于在1400~1500℃条件下将高岭土转化为含氮物相。试样CAS经1500℃热处理后的主要物相为Si 4Al 2O2N 6。

This work aims at exploring the effects of different reductants and reduction methods on the reduction and nitridation of kaolin to achieve high value-added utilization of kaolin.Nitrogen-containing compound powders were prepared with the main starting materials of kaolin fine powder,metal aluminum powder,elemental silicon powder and carbon black by different methods:carbon-aluminum reduction(CA),carbon-silicon reduction(CS),and carbon-aluminum-silicon co-reduction(CAS).The phase composition and microstructure of the specimens were characterized by XRD and SEM.The results show that compared with the carbon-silicon compounding method,the carbon-aluminum and carbon-aluminum-silicon compounding method has stronger reduction capacity;the reduction and nitridation process of kaolin is significantly influenced by the reductant compounding method as well as the reaction temperature;furthermore,the simultaneous introduction of silicon,aluminum and carbon into kaolin facilitates the conversion from kaolin into nitrogen-containing phase at 1400-1500℃;after heat treatment at 1500℃,the main phase of the specimen synthesized by CAS is Si 4Al 2O2N 6.