Fracture in lightweight magnesia spinel refractory using heterogeneous simulation approach with a multiscale framework

Abstract

The fracture behaviour of lightweight magnesia spinel refractory is simulated in this work and compared with common one with dense aggregates to demonstrate the influence of porous composite aggregate. With the consideration of aggregate-matrix microstructure as well as the high heterogeneity of refractory and porous composite aggregate, a microstructure-based heterogeneous continuum modelling strategy is proposed for establishing respectively both the meso-scale interfacial model and refractory multiscale wedge splitting test model. Due to the existence of fine pores and two mineral phases of periclase and spinel, the porous composite aggregate has rougher surface and localized microcracks caused by the thermal misfit of phases. The better interlocking of aggregate/matrix interface and diminishment of wall effect promote the propagation of transgranular cracks. Although the main failure is still in matrix and along interface, the sub-fracture process zone development within the porous composite aggregate further dissipates the energy, which results in the higher fracture energy compared with common magnesia spinel refractory. Two kind of magnesia spinel refractory present very different fracture mechanism.