Determination of Mechanical Parameters of Refractory Materials

Abstract

MgO-C (magnesia-carbon) refractory bricks, used to line vessels in the steel manufacturing process, are subjected to extreme thermal and mechanical conditions, leading to their degradation. The characteristics of the phases present (MgO aggregates, binder resin, graphite sheets, and antioxidants) significantly influence the mechanical behavior of these materials. This study aims to determine mechanical parameters from stress-strain curves obtained from the compression tests of two MgO-C bricks made from sintered magnesia with different levels of purity. Both types of materials were subjected to compressive stresses under two different conditions; (a) at room temperature in normal air atmosphere and (b) at 1400°C under argon flow. For both refractory materials, it was observed that the mechanical behavior, evaluated by the modulus of elasticity (E0.001), fracture resistance (σF), fracture strain (εF), and fracture energy (UF), improves under high-temperature conditions. This effect is mainly attributed to the presence of antioxidants (aluminum and silicon), which, at temperatures above 1000°C, form phases such as spinel (Al2MgO4) and forsterite (Mg2SiO4) that enhance their mechanical strength.