Synthesis of Al 2O 3-SiC Composite and Its Effect on the Properties of Low-carbon MgO-C Refractories

Abstract

Al 2 O 3 -SiC composite was synthesized with pyrophyllite and natural graphite as raw materials by carbothermal reduction reaction under argon atmosphere. The effect of synthesis temperature on phase composition and microstructure was investigated. Low-carbon MgO-C refractories were prepared by using the synthesized Al 2 O 3 -SiC composite as additive. The effect of its addition on the slag penetration and corrosion resistance as well as oxidation resistance of the refractories was investigated, and the slag resistance and oxidation resistance mechanisms of the Al 2 O 3 -SiC composite were also discussed. The results show that the synthesis temperature has a great influence on preparation of Al 2 O 3 -SiC composite. The Al 2 O 3 -SiC composite can be synthesized at 1873-1973 K under argon atmosphere, with pyrophyllite and natural graphite as raw materials, and particle sizes of the composite synthesized at 1973 K are mainly distributed as 1-2 μm. The slag penetration and corrosion resistance of low-carbon MgO-C refractories can be remarkably improved by adding the synthesized Al 2 O 3 -SiC composite, and the oxidation resistance has an improvement to some extent. The increase of slag viscosity and the formation of MgAl 2 O 4 can effectively inhibit the slag penetration and corrosion for the refractories.