Enhancing mechanical properties and thermal shock resistance of steel fiber reinforced mullite castable through magnetic field treatment

In this study, we successfully applied an external magnetic field for the first time in preparing oriented steel fiber reinforced mullite castable (OSFRMC). The impact of the castable's rheology, duration of exposure to the magnetic field and strength of the magnetic field on the orientation of steel fibers and the properties of the refractory castable was investigated. When the duration of exposure to the magnetic field was set at 60 seconds and the strength of the magnetic field was 2.5 mT, an orientation index of steel fibers in the refractory castable of 0.96 was achieved. This specific castable contained 6 wt% of microsilica. Moreover, the castable with a high orientation index (0.96) of steel fibers exhibited significant improvement in mechanical strength and thermal shock resistance compared to the untreated castable. In order to investigate the fracture behavior of steel fiber-reinforced refractory castables with different fiber orientations, a comparative study was conducted using force-displacement curves and digital image correlation techniques. The primary factor behind this improvement is the directional alignment of steel fibers, which enhances the bridging effect and crack deflection toughness within the material.