Preparation and thermal shock behavior of MgAl2O4–C refractories by designing buffering gap around aggregates

Abstract

a new refractory microstructure with thermal stress buffering gap around aggregates was designed. PVA (Polyvinyl alcohol)-coated MgAl2O4 (MA) aggregates were prepared by spray coating technology. The obtained PVA coated MA aggregates were adopted in MgAl2O4–C (MA-C) refractories to research its effect on properties of refractories. The results showed that a uniform PVA layer could be coated on the surface of MA aggregates by spraying coating technique. In the heat treatment process, the PVA around MA aggregates was decomposed and leaves gap between aggregates and matrix, which could offset the aggregates expansion. Due to the reducing thermal expansion coefficient, the thermal shock resistance of refractories was significantly improved. The COMR after thermal shock and the residual strength retention rate of the sample with stress buffering gap were 6.02 MPa and 77.87 %, while that of the sample without stress buffering gap were 5.26 MPa and of 60.32 %.