Hercynite (FeAl2O4) was obtained by Arc Plasma Synthesis (APS) and thermally annealed at 1000 °C for 1, 24 and 36 h respectively, in air. The XRD measurements, that were conducted before and after the annealing, showed an evident alteration of the original hercynite under the influence of temperature and oxygen access.
In this work, four alumina-magnesia, cement-bonded castables were tested at high temperature. Strength was determined by bending test at temperature ranging from room temperature to 1550 °C. As a reference, a high alumina castable was also investigated.
In order to evaluate the effect of magnesia grain size on spinel formation process, four compositions with different dead burned magnesia grain sizes along with fused alumina and graphite were prepared. After pressing, samples were tempered at 220 °C and coked under reducing atmosphere at 1600 °C. Permanent Linear Change (PLC) and physical properties including Bulk Density (BD) and Apparent Porosity (AP) were measured.
Carbon bonded magnesia and magnesia-alumina bricks are used in the side walls and bottom of steel ladles for more than 30 years.
Antioxidants are common additives to carbon-containing refractories. They reinforce the carbon-bond by creation of new oxidic or non-oxidic bonds while reacting with refractory components and ambient oxygen. Strength is increased and porosity reduced, but elasticity and slag resistance as well as resistance towards thermal decomposition is lowered, particularly under vacuum conditions.