关键词: 菱镁矿尾矿, 镁质复合材料, 碳化硅, 抗热震性

Abstract: To improve the utilization rate and application value of magnesite tailings,magnesia composites were prepared using light burnt powder of magnesite tailings as the raw material,silicon powder and 95-graphite as additives and phenolic resin as the binder by the solid-state reaction pressureless sintering method.The effects of the Si powder and graphite powder additions on the cold modulus of rupture,density,linear change rate,thermal shock resistance,microstructure and phase composition of the composites were studied in the carbon embedded atmosphere.The results show that with the increasing additions of silicon powder and graphite powder,the contents of forsterite (M₂S) and SiC in the materials increase,finally forming an M₂S-SiC-C multiphase material with M₂S as the main crystal phase.The CO and SiO gases produced during reaction are not conducive to material sintering,leading to the decrease of the cold modulus of rupture,bulk density and linear shrinkage,and the increase of the porosity.After thermal shock,the strength retention ratio of the materials increases significantly compared with that of the sample without additives,because both the increased M₂S content and the generation of SiC whiskers in the materials are beneficial to improving the thermal shock resistance.

Key words: magnesite tailings, magnesia composites, silicon carbide, thermal shock resistance