Synthesis of bauxite based β-SiAION by compound reduction nitridation

摘要

The process of synthesizing bauxite based β-SiAlON by using carbon silicon composite reducing agent was studied.Specimens prepared by mixing bauxite (Al2O3 68％),carbon black and silicon are nitrided at 1100～ 1550C for 6h.The mass change ratio of the specimens are determined;Phase composition and microstructure of some specimens are examined by XRD,SEM and EDS.The results are compared with those of specimens using Si and C separately as reducing agent.It is found that at 1100～1200°C only Si reacts with N2 and SiO2 to form Si2N2O; At 1300～1400°C,C takes part in reduction-nitridation with subsequent formation of SiAlON; At 1450～1550°C,there is noticeable increase in β-SiAlON formation,the optimum temperature is 1500°C.The amount of β-SiAlON formed is higher and crystale growth is better than that of single reducing agent.