Microstructure and properties of MgO–C refractory with different carbon contents

Abstract

Magnesia-carbon (MgO–C) refractory is considered as the most crucial lining material in steelmaking furnaces. To provide reference for producing high performance MgO–C refractory containing different carbon contents, the microstructure, mechanical strength, thermal shock resistance and thermal properties of this material with 1–18 wt% flake graphite were studied systematically in this work. The results showed that carbon content had small effect on microstructural evolution of MgO–C refractory after high temperature treatment, mainly MgAl2O4 particles, Al4C3 whiskers and plate-/whisker-shaped AlN formed in the matrix of all specimens. As carbon content added increased gradually, fracture strength of specimens exhibited a reduced tendency whereas the corresponding fracture displacements became higher and higher owing mainly to good sliding ability of flake graphite. Furthermore, the increase in carbon content reduced thermal expansion rate of specimens and correspondingly increased thermal conductivity, consequently contributing to enhanced resistance to thermal shock of MgO–C refractory.