Performance investigation of resin bonded ferro-silicon nitride-corundum refractories after creep at 1300 °C

Novel tempered resin bonded ferro-silicon nitride-corundum refractories containing 0 wt%, 15 wt% and 25 wt% ferro-silicon nitride were prepared respectively. Creep tests were performed under a load of 0.2 MPa at a temperature of 1300 °C for 50 h in air. The results showed that creep performance was significantly improved by the addition of ferro-silicon nitride. Ferro-silicon nitride-corundum containing 15 wt% ferro-silicon nitride initially presented a steady-state stage and was able to remain stable from the beginning of the holding time until 50 h of creep testing. All the specimens exhibited cold crushing strength more than 100 MPa both before and after creep testing. Phase composition and microstructure were analyzed following the creep experiments. The results showed that Si2N2O and O'-sialon crystals formed in situ during creep testing, in addition to the conversion of α-Si3N4 to β-Si3N4. Liquid Fe3Si from the ferro-silicon nitride component accelerated the formation of the O'-sialon and prolonged the growth of β-Si3N4, which improved the creep performance significantly. Fe3Si liquid migrated into the pores, and some Fe3Si coexisted with residual carbon from the resin, which filled a part of pores and protected the specimens from severe oxidation.