Thermomechanical evaluation of MgO–C commercial bricks

Abstract

MgO–C bricks are used extensively in the steelmaking industry due to their excellent properties, which includes thermal shock resistance. In this work, the thermomechanical properties of three different MgO–C bricks with currently used compositions are evaluated and analyzed together in order to acquire a better understanding of the materials' behavior. An alternative thermal shock test to evaluate the MgO–C bricks is proposed in which specimens are cooled from 1050 °C to room temperature using oil and air as alternative quenching media. Diametral compression tests are used to determine the residual strength as a damage indicator. Stress-strain curves in compression (at RT and 1200 °C) and dilatometric curves (up to 1400 °C) are also obtained in order to determine the thermomechanical behavior of the evaluated refractories. The brick with the higher amounts of aluminum and graphite, but bonded with resin, exhibited the best response to thermal shock (higher residual mechanical strength). Nevertheless, the analysis of the results as a whole suggests that the material's condition after the first thermal treatment is the main reason for its loss of integrity, more so than the subsequent thermal shocks.