铝碳复合还原氮化制备矾土基β-SiAlON

Synthesis of Bauxite Based β-SiAlON by Aluminum Carbon Compound Reduction Nitridation

分别以复合还原剂铝碳,单一还原剂铝、碳还原氮化铝土矿(Al2O3含量为68%)(文中含量均为质量分数)制备β-SiAlON。利用XRD、SEM和EDS等检测手段和试样在1 100～1 550℃温度范围的质量变化率,研究了制备β-SiAlON的相变过程和铝碳复合还原剂对生成β-SiAlON的含量和显微结构的影响。结果表明:1 100℃时,铝粉氮化形成AlN,同时铝粉还原二氧化硅生成Si;1 200℃时,Si和氮气反应生成Si3N4;1 300～1 350℃,还原剂碳参与还原反应,β-SiAlON开始生成;1 400～1 550℃时,进入固溶阶段,β-SiAlON量增多,1 550℃时含量达到最高。与单一还原剂相比,铝碳复合还原剂制备的β-SiAlON的晶体截面形态呈长柱状,结晶发育较好。

The bauxite based β-SiAlON was synthesized by using aluminum carbon compound reducing agent and separate Al and C reducing agents respectively.The phase transformation of β-SiAlON and the effects of aluminum carbon compound reducing agent on the generated β-SiAlON content and microstructure were studied by using mass change ratio of the specimens and XRD,SEM,EDS analysis.The results show that at 1 100 ℃ only Al reacts with N2 and SiO2 to form AlN and Si.At 1 200 ℃,Si reacts with N2 to form Si3N4.At 1 300~1 350 ℃,C takes part in reduction-nitridation with subsequent formation of β-SiAlON.At 1 400~1 550 ℃,there is noticeable increase in β-SiAlON formation,and the optimum temperature is 1 500 ℃.The crystal shape of β-SiAlON prepared by compound reducing agent is long column,and the crystal growth is better than that of single reducing agent.